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Research progress on molecular regulation mechanism of skin ulcer syndrome in sea cucumber Apostichopus japonicus：a review
LI Chenghua
Journal of Dalian Ocean University    2021, 36 (3): 355-373.   DOI: 10.16535/j.cnki.dlhyxb.2021-086
Abstract （6375）   HTML （182）    PDF（pc） （8447KB）（3596）       Save
Since 2003, the development speed and scale of the sea cucumber  Apostichopus   japonicus  industry have reached unprecedented levels, forming the “fifth” wave of marine aquaculture industry in China after kelp, prawns, scallops, and marine fish farming. With the expansion of breeding scale and density, disease problems have become increasingly prominent, and have gradually become a bottleneck for the healthy development of sea cucumber industry, posing a huge threat to the ecological environment and food safety, among which the skin ulcer syndrome (SUS) is the most representative. The main pathogens of sea cucumber suffered from SUS, systematical immune regulation mechanism of sea cucumber against pathogen infection, the research progress of representative pathogenic mechanisms and ecological control methods of sea cucumber diseases are discussed in detail. Corresponding development countermeasures are proposed for the healthy and sustainable development of the sea cucumber industry, the pathogenic mechanism of pathogens and the research on the occurrence of environmental control diseases in order to provide reference with the construction of green and healthy sea cucumber disease prevention and control strategies.
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Artificial propagation and embryonic and larval development of Chinese hook snout carp Opsariichthys bidens
LUO Xiaonian, DUAN Youjian, ZHANG Xiaojing, ALIDA·Xiamuxiding, LI Jiao, WU Chen, LI Wenkang, JI Chenyue, CHANG Jiantai
Journal of Dalian Ocean University    2022, 37 (4): 550-557.   DOI: 10.16535/j.cnki.dlhyxb.2021-222
Abstract （6303）      PDF（pc） （4024KB）（3637）       Save
In order to realize the whole process of artificial propagation and culture of wild Chinese hook snout carp  Opsariichthys   bidens , the fish was induced to spawn by hormone injection, the fertilized eggs were incubated and fry and juveniles were reared in a pond at Xingda Farm in Liaoyang County, Liaoning Province from 2018 to 2021.Meanwhile embryonic and larval development was observed under a microscope. It was found that male fish were maturity at 1 +  year old, and the female at 2 +  years old in a pond culture. The pond-cultured Chinese hook snout carp spawned from May 10th to May 29th in Liaoyang area, and had average success rate of 73.8%, fertilization rate of 81.3% and hatching rate of 78.8% by injection of mixed drugs (LHRH-A 2  4-8 μg/kg+DOM 4-8 mg/kg+HCG 1 000-2 000 IU/kg), artificial dry insemination, combined hatching basket and hatching bucket incubation method. The fertilized eggs of Chinese hook snout carp are orange-yellow in color without adhesion, and the spawners had effect time of 25 to 27 h after hormone injection at water temperature from 18 to 20 ℃ (one injection). The embryonic development was divided into 7 stages including blastoderm, cleavage, blastula, gastrula, neuroblastoma, organogenesis, and hatching and 24 sub-stages, lasting about 62 h 6 min, with total incubation accumulative temperature of 1 199.91 ℃·h. The larvae swam horizontally over 5 to 6 days post hatching, and the 1-day-old Chinese hook snout carp larvae had total length of (5.13±0.63)mm. The larvae became the mixed nutrition period at the 10-day-old age, and the 12-day-old postlarvae had exhaustion of the yolk sac, and allometric growth. Total 14 000 F1 fry were obtained in the ponds in 2018, and 2 120 000 F2 fry were reared for two consecutive years from 2020 to 2021. The findings realized the whole procedure of artificial propagation of Chinese hook snout carp for the first time.
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Histological structure and digestive enzyme activity of intestine in sea cucumber Apostichopus japonicus
WANG Han, WANG Haona, ZHAO Ye
Journal of Dalian Ocean University    2022, 37 (5): 823-829.   DOI: 10.16535/j.cnki.dlhyxb.2021-315
Abstract （6259）   HTML （169）    PDF（pc） （3868KB）（3193）       Save
In order to explore the relationship between histological structure and function of sea cucumber  Apostichopus   japonicus , histological observation and digestive enzyme activities were conducted to investigate the structure, mucous cell distribution features and function of different intestinal segments in the sea cucumber with body weight of (43.58±6.78)g by routine paraffin tissue section with hematoxylin-eosin (H.E) and alcian blue-peri-odie acid schiff (AB-PAS) staining. The results showed that all of the three intestinal segments consisted of mucosa, submucosa, muscularis and serosa, with the maximal mucosa and muscularis thickness in foregut, significantly higher than that in midgut and hindgut ( P <0.05), significantly higher submucosa thickness in hindgut than that in midgut and foregut ( P <0.05), without significant difference in the serosa thickness in foregut, midgut and hindgut ( P >0.05), and decrease in the height and number of mucosa fold successively from foregut to hindgut. There were four types of mucous cells (type Ⅰ, type Ⅱ, type Ⅲ, and type Ⅳ) in different segments of intestine of the sea cucumber, mainly focusing on type Ⅲ and type Ⅳ. The total mucous cell number was found to be decreased from foregut to hindgut, significantly higher four types of mucous cells in foregut than those in hindgut ( P <0.05). Moreover, the activities of trypsin, amylase and alkaline phosphatase all showed decreased levels from the foregut to the hindgut, with significantly higher enzyme activities in foregut than those in hindgut ( P <0.05), and there was significant difference in lipase activity between foregut and midgut ( P <0.05). These data suggests that the foregut has the strongest digestion and absorption capacity, the midgut is weaker, and the hindgut is the weakest. While the hindgut has a strong ability to secrete acidic mucin and has a certain mucosal immune portection function.
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Effects of low temperature stress on survival and expression of fatty acid metabolism-related genes SCD，FAD and ACC indifferent populations of Manila clam Ruditapes philippinarum
LI Ning, NIE Hongtao, LI Qiang, HUO Zhongming, YAN Xiwu
Journal of Dalian Ocean University    2022, 37 (4): 636-642.   DOI: 10.16535/j.cnki.dlhyxb.2021-243
Abstract （6256）   HTML （74）    PDF（pc） （2777KB）（3480）       Save
In order to probe into the effects of low temperature stress on the survival and fatty acid metabolism related genes of Manila clam  Ruditapes   philippinarum  zebra clam No.2, the survival differences and three genes related to fatty acid metabolisms including stearoyl coenzyme A desaturase ( SCD ), fatty acid desaturase ( FAD ) and acetyl coenzyme A carboxylase ( ACC ) in gill tissues were investigated in three populations including zebra clam No.2, Dalian in Liaoning Province and Beihai in Guangxi under low temperature stress of -1 (in a refrigerator)， 4 (in a recirculating tank)， and 12 ℃ (room temperature) by qRT-PCR. The results showed that after acute low temperature (-1, 4 ℃) stress for 9 d, the order of the survival rates of Manila clam populations was expressed as zebra clam No.2 > Dalian population in Liaoning > Beihai population in Guangxi. The expression of three fatty acid metabolism related genes in gill tissues was significantly affected by temperature ( P <0.05 ).With the temperature decreasing from 12 ℃ to -1 ℃, the expression level of the three genes were increased under 4 ℃ or -1 ℃ cold stress. Compared with 0 h, the expression levels of  SCD  and  FAD  genes in gill tissues of zebra clam No.2, Beihai population and Dalian population were significantly up-regulated from 12 to 72 h( P <0.05). The expression levels of  ACC  genes in the three populations were significantly up-regulated at different time, and the up-regulation range of the three genes in the gills of zebra clam No.2 was significantly higher than that in Beihai population and Dalian population ( P <0.05). The results demonstrated that the survival rate and low temperature tolerance of zebra clam No.2 at -1 ℃ were apparently higher than Dalian, Liaoning and Beihai, Guangxi. In addition, the high expression level of  SCD ,  FAD  and  ACC  genes of zebra clam No.2 might be related to its strong tolerance and high resistance to low temperature.
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Current fish community structure and its relationship with environmental factors in Gucheng Lake, Nanjing China
LIU Pengfei, JING Li, REN Long, KUANG Zhen, ZHAN Zhengjun, HU Changsui, XU Dongpo
Journal of Dalian Ocean University    2022, 37 (5): 841-849.   DOI: 10.16535/j.cnki.dlhyxb.2021-275
Abstract （6254）   HTML （119）    PDF（pc） （1901KB）（3218）       Save
In order to understand the current status of fish communities in Gucheng Lake (30°14′-31°18′N, 118°53′-118°57′E), fish community structure was surveyed in 8 sampling sites in Gucheng Lake, a land-sealed lake in the lower reaches of the Yangtze River in January (winter), July (summer), November (autumn) 2017 and April 2018 (spring) by multi-mesh sized gillnets and fixed series cage traps. Water quality was quantitatively determined in Gucheng Lake and relationship between the structure of fish communities and environmental factors was analyzed. A total of 29 species of fish were collected in the survey, belonging to 22 genera, 6 families and 5 orders, with the vast majority (25 species) in Cypriniformes, accounting for 86.21% of the number of fish species. There was only dominant species  Toxabramis   swinhonis , without significant temporal and spatial difference in fish diversity index ( P >0.05), and with low level of the Shannon-Wiener diversity index (H). The RDA analysis revealed that total nitrogen content (TN), permanganate index (COD Mn ), and turbidity (TUR) led to significant effects on the temporal and spatial differences of fish community structure ( P <0.05). From 2017 to 2018, the fish resources of Gucheng Lake were declined significantly compared with those in the 1980s,the number of species declined by 64.63%. It is suggested that the restoration of fishery resources be promoted by improving hydrological connectivity in the basin and by promoting ecological fishery in large water areas. To a certain extent, the finding has supplemented the gaps in the study of fish communities in Gucheng Lake in the new era, and has to some extent significance in the protection of fish resources in the waters.
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cDNA cloning and expression distribution of Wnt9 gene in adult tissues and embryonic development in sea cucumber Apostichopus japonicas
MA Deyou, YU Lianlian, LIN Weigang, WANG Chengliang, DING Jun, CHANG Yaqing
Journal of Dalian Ocean University    2022, 37 (3): 394-402.   DOI: 10.16535/j.cnki.dlhyxb.2022-138
Abstract （6237）   HTML （137）    PDF（pc） （15558KB）（3240）       Save
In order to understand of the regulatory roles of  Wnt 9 gene in early development of sea cucumber  Apostichopus   japonicus ,the molecular characteristic and dynamic expression pattern of  Wnt 9 gene were investigated through RACE,real-time PCR and whole mount in situ hybridization techniques.It was found that the full-length cDNA of  Wnt 9 gene in sea sucumber was 1 603 bp,with an 1 104 bp open reading frame encoding 367 amino acid residues containing a conserved Wnt1 domain.Wnt9 shared common features of Wnt family including N-glycosylation sites and conserved cysteine sequences.Phylogenetic analysis revealed that the deduced amino acid sequence of Wnt9 in sea sucumber was highly similar to that of Wnt9a and Wnt9a like from the genetically close species in echinoderm.qRT-PCR analysis indicated that  Wnt 9 gene was differentially expressed in adult tissues of sea sucumber,with the maximum in body wall ( P <0.05),and the minimum in gonad ( P <0.05). Wnt 9 was expressed throughout the embryonic development of sea sucumber,and its expression levels were increased significantly at the doliolaria stage and peaked at the juvenile stage ( P <0.05).Further investigation using whole mount in situ hybridization showed that  Wnt 9 mRNA positive signals were observed in doliolaria,and enhanced in juveniles,indicating that  Wnt 9 gene has effect on the embryonic growth and development,especially postmetamorphic stage in this important economic species.The findings lay a foundation for exploring the formation of the head-to-tail axis and the morphological remodeling during metamorphosis of sea cucumber.
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Cloning, expression and photoperiodic response of gonad-inhibiting hormone (GIH) gene in scalloped spiny lobster Panulirus homarus
LUO Jiajun, ZHUO Hongbiao, CHEN Juntao, LIANG Huafang, WEN Chongqing?
Journal of Dalian Ocean University    2021, 36 (5): 727-735.   DOI: 10.16535/j.cnki.dlhyxb.2020-291
Abstract （6231）   HTML （3）    PDF（pc） （4740KB）（3480）       Save
In order to investigate the expression of gonad-inhibiting hormone (GIH) gene ( PhGIH ) in tissue distribution of scalloped spiny lobster  Panulirus   homarus  in different ovarian development cycles and response of GIH to different photoperiods, the full-length cDNA sequence of  PhGIH  in eyestalk of scalloped spiny lobster were cloned by RACE, expressed of  PhGIH  in different tissues and ovary stages by qPCR,and the effects of different photoperiods (12L∶12D, 13L∶11D and 14L∶10D ) on the ovarian development of scalloped spiny lobster were compared through ovarian color and morphology, histological section and gonadosomatic index. The results showed that the length of  PhGIH  was 1 206 bp including a 354 bp open reading frame (ORF) encoding 117 amino acids. The amino acids sequence of  Ph GIH consisted of signal peptide with 39 amino acids and mature peptide with 78 amino acids, which had the typical characteristics of CHH family type II peptide hormones. The homology analysis showed that the gene  Ph GIH had the maximal identity (56.76%) with Cape rock lobster  Jasus   lalandii . Phylogenetic tree revealed that the  Ph GIH has the shortest evolutional distance with Cape rock lobster. The Quantitative Real-time PCR analysis showed that  PhGIH  was widely expressed in various organizations, with the maximal expression in the eyestalk( P <0.01), and the expression of  PhGIH  in the eyestalk was as the maturation of ovary. The results of photoperiod experiments indicated that ovarian development was progressed smoothly at 14L∶10D. At 92 days, the GSI was significantly increased ( P <0.05) and  PhGIH  expression in the eyestalk was significantly decreased ( P <0.05). The paraffin tissue sections showed that the ovary was orange in color and mainly composed of mature oocytes. The findings indicated that the  GIH  gene might play an important role in the development of ovary in scalloped spiny lobster. The photoperiod of 14L∶10D had the most obvious effect on promoting ovarian development.
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Spatio-temporal pattern and influencing factors of phytoplankton community structure in National Aquatic Germplasm Resources Reserve of common carp Cyprinus carpio and longsnout catfish Leiocassis longirostris in Huaihe River
WANG Dongwei, GONG Jiang, YANG Xiaoxi, ZHAO Wei, ZHOU Yanfeng
Journal of Dalian Ocean University    2022, 37 (4): 658-667.   DOI: 10.16535/j.cnki.dlhyxb.2021-311
Abstract （6214）   HTML （4）    PDF（pc） （4484KB）（3418）       Save
 In order to understand the spatio-temporal pattern of phytoplankton community structure and its relationship with environmental factors in common carp  Cyprinus   carpio  and longsnout catfish  Leiocassis   longirostris  National Aquatic Germplasm Resource Reserve in the Huaihe River (117°05′39″-117°15′31″E, 32°47′59″-33°00′03″N), phytoplankton and water quality were seasonally investigated in 18 sampling sites in the reserve in winter (January), spring (April), summer (August) and autumn (October) 2020.The results showed that 143 species of phytoplankton in 71 genera in 8 phyla, mainly Cyanophyta, Bacillariophyta and Chlorophyta, accounting for 85.31% in total, were identified in the reserve during the survey period. The dominant species of phytoplankton were mainly  Cyclotella   meneghiniana ,  Chroomonas   acuta  and other 13 species. The variation of Shannon-Wiener diversity index of phytoplankton in the reserve was ranged from 1.48 to 3.08, with significantly lower diversity index in spring and winter than that in summer and autumn ( P <0.05); Pielou evenness index was ranged from 0.46 to 0.96, without significant seasonal difference ( P >0.05). The range of Margalef richness index was varied from 0.48 to 2.58, significantly lower in winter than in the other three seasons, with the maximum in summer and the minimum in winter. The phytoplankton cell density in the reserve was ranged from 9.84×10 4  to 7.86×10 7  cells/L, and the variation range of biomass was varied from 0.02 to 29.07 mg/L. There was no significant difference in phytoplankton density and biomass in seasons, but significant difference in the waters of Guohe River, higher than that in the main stream of Huaihe River ( P <0.05). The main environmental factors affecting the spatio-temporal distribution of phytoplankton communities in the reserve were transparency (SD), total nitrogen (TN), water depth (WD) and permanganate index (COD Mn ) in spring, summer, autumn and winter, respectively. It was found that the watersheds in the reserve were all in a state of mild eutrophication, without significant difference in the phytoplankton density and biomass in time pattern, significantly higher in the Guohe River than that in the main stream of the Huaihe River. It is suggested that the corresponding environmental factors should be paid attention in different seasons to maintain the diversity of phytoplankton.
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Effects of dietary red koji rice on growth performance, body colour and some hematological and hepatopancreas biochemical indices of juvenile red-white koi carp Cyprinus carpio
CUI Pei, SHANG Dongwei, LIU Wenjun, SUN Jinhui
Journal of Dalian Ocean University    2021, 36 (4): 595-602.   DOI: 10.16535/j.cnki.dlhyxb.2020-213
Abstract （6199）   HTML （4）    PDF（pc） （504KB）（3430）       Save
A feeding trial was conducted to evaluate the effects of dietary red koji rice on growth performance, body colour and some hematological and hepatopancreas biochemical indices of juvenile red-white koi carp  Cyprinus   carpio .The red-white koi carp with body mass of(8.79±1.80)g were reared in a plastic tank and fed basic diet(control group)and supplemented with red koji rice at a dose of 0, 0.5, 1.0, 1.5, and 3.0 mg/kg diet for 56 days, and then fed the diet without red koji rice for 14 days at water temperature of(25.0±1.0)℃.Each diet was randomly assigned to triplicate groups of 30 juvenile koi carp.The results showed that the fish fed the diets supplemented with red koji rice had significantly higher weight gain(WG), specific growth rate(SGR), feed efficiency(FE)and lower glucose concentrations and aspartate transaminase(AST)activity( P <0.05).There was significantly higher glutathione peroxidase(GSH-PX)activity in the fish fed the diets containing red koji rice of 1.5 g/kg, and significantly higher malondialdehyde(MDA)concentration in the fish in the high dose red koji rice group(3.0 g/kg)( P <0.05).No significant influence of the dietary red koji rice levels on superoxide dismutase(SOD)and catalase(CAT)activities was observed in the hepatopancreas of the fish fed the diets containing red koji rice( P >0.05), with the maximal  a *  value and carotenoids concentration in the skin of the fish fed the diet containing red koji rice at dose of 1.0 g/kg.The fish fed the diet containing red koji rice at dose of 1.0 g/kg had significantly higer  a *  than those animals fed the basal diet did( P <0.05), even 7th or 14th days after all the fish fed the diet without red koji rice.In conclusion, the findings indicated that dietary addition of red koji rice led to improve growth performance, and adjust glucose concentrations, with significant impact on the body colour of juvenile koi carp and the optimal level of 1.0 g/kg under this experimental conditions.
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Artificial reproduction and embryonic development of hybrid sturgeon (Huso dauricus♀×Acipenser schrenckii♂) and Amur sturgeon A.schrenckii
XIAO Xinxin, LUO Xiaonian, FU Xianfei, JIANG Xu, DUAN Youjian, LI Jiao, LIU Yinglin
Journal of Dalian Ocean University    2022, 37 (5): 764-774.   DOI: 10.16535/j.cnki.dlhyxb.2021-219
Abstract （6193）   HTML （165）    PDF（pc） （6252KB）（3049）       Save
In order to explored the reproductive biology of hybrid sturgeon ( Huso   dauricus ♀× Acipenser   schrenckii ♂), 5 batches (10 pairs) of hybrid sturgeon and 1 batch (2 pairs) Amur sturgeon ( A.schrenckii ) were induced to spawn by hormone injection, caesarean section, and artificial insemination methods from March to May in 2021. The results showed that 3.79 million fertilized eggs of the hybrid sturgeon were obtained, with average fertilization rate of 82.9%, the average hatching rate of 70.44%, and 2.176 million larvae. In the Amur sturgeon, 0.87 million fertilized eggs were obtained, with the average fertilization rate of 82.2%, the average hatching rate of 63.20%, and 0.542 million larvae. At water temperature of 16 to 17 ℃, the 123 to 155 h were took from fertilization to hatching, with total accumulative temperature of 2 102 to 2 445 ℃·h in the hybrid sturgeon, and 116 to 138 h were took from fertilization to hatching, with total accumulative temperature of 1 856 to 2 108 ℃·h in the Amur sturgeon. The demersal adhesive fertillized eggs of hybrid sturgeon and Amur sturgeon had similar embryo development sequence, with radiation cleavage. The embryonic development of hybrid sturgeon was morphologically divided into 9 continuous stages including 32 substages, and the embryonic development of Amur sturgeon was divided into 9 continuous stages and 28 substages. The typical differences included as the following: “C”-shaped heart in heart beating stage in hybrid sturgeon, but with “S”-shaped heart in the Amur sturgeon. Besides, the end of the embryotail was close to the heart of the hybrid sturgeon when the heart begins to beat regularly, while the Amur sturgeon was not yet. When hatching, the tail tip of the hybrid sturgeon larvae was over the head, while the sturgeon just reached or slightly over the head. In this experiment, hybrid sturgeon had higher reproductive efficiency (the maximal fertilization rate of 97.8%, and the maximal hatching rate of 89.8%). Embryonic development of hybrid sturgeon was more similar to that of  Huso   dauricus , the hybrid sturgeon showing the characteristics of maternal inheritance.
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Effects of dietary fish meal replaced by soybean meal and supplemented with different organic acids on growth, immunity and intestinal microflora of Pacific white leg shrimp Litopenaeus vannamei
ZHAO Xidie, ZHENG Hailing, LIU Mingming, TANG Yu, QIAO Xiuting, LIU Qun, HUANG Zonghai, CHENG Zhenyan
Journal of Dalian Ocean University    2021, 36 (6): 966-975.   DOI: 10.16535/j.cnki.dlhyxb.2021-007
Abstract （6182）   HTML （13）    PDF（pc） （7587KB）（3429）       Save
A feeding trial was conducted to study the effects of dietary organic acids on the growth and intestinal health of Pacific white leg shrimp  Litopenaeus   vannamei  fed low fish meal diets. Pacific white leg shrimp with initial body mass of (7.54±0.40)g were randomly reared into 18 cages of each 100 cm ×100 cm ×150 cm at stocking rate of 40 individuals per cage and fed diets containing 24% fish meal (positive control group), 18% fish meal (negative control group) and 18% fish meal diets supplemented with sodium citrate, sodium butyrate, sodium propionate and fumaric acid, respectively, at a dose of 0.3% at water temperature of 24-30 ℃ for 42 days. Results showed that there were significant reduce in weight gain rate (WGR) and specific growth rate (SGR) and significant increase in food conversion ratio (FCR) in the negative control group compared with the positive control group( P <0.05). The SGR and WGR were shown to be significantly increased and FCR was found to be significantly decreased ( P <0.05) in the Pacific white leg shrimp fed the diets containing 0.3% sodium butyrate and sodium citrate, without significant differences in the WGR and SGR in the Pacific white leg shrimp fed the diets containing 0.3% sodium propionate and fumaric acid ( P >0.05). The shrimp in the negative control group had significantly lower immunity compared with the shrimp in the positive control group ( P <0.05), and improved immunity when the shrimp fed the diets containing 0.3% sodium citrate and sodium butyrate, with increase in the activities of serum acid phosphatase (ACP), alkaline phosphatase (AKP), lysozyme (LSZ) and superoxide dismutase (SOD), and decrease in the malondialdehyde (MDA) content, the activities of serum ACP and the MDA content being not significantly different from the shrimp in the positive control group ( P >0.05). There were lower serum MDA content in the shrimp fed the diets containing 0.3% sodium propionate ( P <0.05) compared with the shrimp in the negative group, increased the activities of serum LSZ ( P <0.05) and decreased the activities of serum ACP, AKP, SOD ( P <0.05) in the shrimp in 0.3% fumaric acid group. There was no significant difference in Alpha diversity of the shrimp intestinal flora in each group ( P >0.05). The decrease in abundance of Actinomycota was observed in the negative control group, while the decrease in abundance of Actinomycota, as well as the abundance of Bifidobacterium and Bacteroides, was improved in the shrimp fed the diets supplemented with 0.3% sodium citric ( P <0.05). The abundance of Fusobacterium was also found to be increased in the shrimp fed the diets supplemented with 0.3% sodium butyrate ( P <0.05). The findings indicate that the low fish meal diet supplemented with organic acids led to improve the growth and immune capacity of Pacific white leg shrimp, and regulated the balance of intestinal microorganism, among which 0.3% sodium citrate and 0.3% sodium butyrate had the best effects.
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Heavy metal contamination and health risk assessment of tiger puffer Takifugu rubripes farmed in a recirculating tank
WANG Xuankai, ZHAO Tong, YUE Yang, WANG Houyu, QU Baocheng, XIONG Yuyu, ZHANG Yufeng
Journal of Dalian Ocean University    2022, 37 (4): 650-657.   DOI: 10.16535/j.cnki.dlhyxb.2021-280
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In order to evaluate the quality and safety of tiger puffer  Takifugu   rubripes  farmed in a recirculating tank, the contents of lead (Pb), cadmium (Cd), mercury (Hg), copper (Cu) and chromium (Cr) were determined in tiger puffer with average body weight of 2.3 g (juvenile), 1 091.4 g(sub-adult), and 1 718.1 g (adult) sampled from an industrial aquaculture enterprise in Dalian, Liaoning Province at different developmental by inductively coupled plasma mass spectrometry (ICP-MS). The results showed that the contents of different heavy metals in the body of the tiger puffer were not shown to exceed the safety standards of “National standards for food safety, limits of pollutants in food”(GB 2762—2017) and “Limits of toxic and harmful substances in non polluted food and aquatic products”(NY 5073—2006). The changes in heavy metal contents in the tiger puffer in different culture stages showed that Cu and Cr were the main metal elements enriched in liver ( P <0.05) and Cr in muscle ( P <0.05), without significant difference in contents of Cd, Hg, Cu and Cr in tiger puffer in different developmental stages ( P >0.05), and with significant difference in the contents of Cd, Hg and Cu in different tissues ( P <0.05). The assessment of heavy metal pollution in fish body showed that single factor pollution index and Nemerow comprehensive pollution index were in the non-pollution range, and according to the estimated daily intake, carcinogenic risk and non-carcinogenic risk, the contribution of daily intakes to health risks is expected to be small, cancer risk in children and adults is within acceptable limits, and non-cancer risk is negligible, but the overall health risk in children is slightly higher than that in adults. The findings indicate that the levels of heavy metals in tiger puffer can be controlled within a safe range in the recirculating aquaculture system.
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Differences in growth and survival of Yesso scallop Patinopecten yessoensis cultured on floating raft in Changhai County between 2017 and 2018
ZHOU Kai, LIU Chao, KONG Ning, YI Qilin, YANG Chuanyan
Journal of Dalian Ocean University    2022, 37 (3): 482-488.   DOI: 10.16535/j.cnki.dlhyxb.2021-266
Abstract （6126）   HTML （149）    PDF（pc） （1240KB）（3239）       Save
In order to reveal the relationship among environmental factors,energy metabolism and immune defense ability of Yesso scallop  Patinopecten   yessoensis ,the interannual differences in growth related indices including shell length,body weight,condition factor,survival rate and prevalence as well as their influencing factors were surveyed in Yesso scallop cultured in floating raft in Changhai County (39°17′23″N,122°44′18″E),Dalian Liaoning province,China,in March,May,June and July of 2017 and 2018.The results showed that the water temperature was significantly lower in the aquaculture sea area of Changhai County in March,June and July of 2018 than that in the same period of 2017 ( P <0.05),while the dissolved oxygen contents in March,June and July was significantly higher than that in the same period of 2017 ( P <0.05).The shell length,body weight and condifition of the scallop in June and July of 2018 were significantly higher than those in the same period in 2017 ( P <0.05).The glycogen contents in adductor muscle were significantly higher in the scallop in March and June of 2018 and the survival rate from May to June and June to July than those in the same period of 2017 ( P <0.05).In 2018,the activities of superoxide dismutase (SOD) in adductor muscle of the scallop in March,June and July,the content of malondialdehyde (MDA) in adductor muscle of scallop in May and June,the content of heat shock protein (HSP70) in adductor muscle of the scallop in March,May and June,and the prevalence from May to June and June to July were significantly lower than those in the same period in 2017 ( P <0.05).It was found that the immune response intensity of scallop under appropriate environmental conditions is reduced,and the adductor muscle accumulate more glycogen,so as to provide more sufficient energy reserves for other physiological activities,which further reduce the prevalence,improve the survival rate and promote the healthy growth of scallops in floating raft culture.The findings will provide data support and theoretical basis for early disease warning and prediction of scallop in floating raft culture and healthy culture in Changhai County and the similar sea areas.
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Application of an electronic monitoring system for video target detection in tuna longline fishing based on YOLOV5 deep learning model
WANG Shuxian, ZHANG Shengmao, ZHU Wenbin, SUN Yongwen, YANG Yuhao, SUI Jianghua, SHEN Lie, SHEN Jieran
Journal of Dalian Ocean University    2021, 36 (5): 842-850.   DOI: 10.16535/j.cnki.dlhyxb.2020-333
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In order to evaluate the operation quality of the tuna longline fishing system, reduce labor costs, and extract information such as float and tuna quantity from the electronic monitoring system of the tuna longline fishing system, a method for detecting floating ball and tuna target in tuna longline fishing electronic monitoring system was proposed based on deep learning YOLOV5 network model. A total of 15 578 key frames containing target float or tuna were intercepted from the video surveillance data of the HNY722 ocean-going fishing vessel EMS, and divided all key frames and their mark files into 14 178 training data and 1 400 verification data, based on YOLOV5s, YOLOV5l, YOLOV5m and TOLOV5x deep learning neural network models. The group training tests were designed to compare training effects. The results showed that the four neural network models trained in this article all completed the target detection task of the tuna longline electronic monitoring system. However, the choice of the network model had a highly significant impact on the parameters of GIoU loss, objectness loss, precision, recall, mAP@0.5, mAP@0.5∶0.95( P <0.05), without significant impact on the classification loss parameters( P <0.05). The better detection results were observed in YOLOV5m network models, with mAP@0.5 values of 99.1% in YOLOV5l network and 99.2% in YOLOV5m network, and the recall rates of 98.4% in YOLOV5l network and 98.3% in YOLOV5m network. However, YOLOV5m was inferior to YOLOV5l in performance such as GIoU loss. The finding indicates that YOLOV5l is the most suitable network model for target detection in tuna longline electronic monitoring system among the four network models of YOLOV5s, YOLOV5l, YOLOV5m and YOLOV5x.
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Effects of Zn 2+ stress on expression of key antioxidant genes and antioxidant enzyme activities in eckloni naked carp Gymnocypris eckloni
RAN Fengxia, JIN Wenjie, DUANZHI Zhuoma, HUANG Shen, LIU Yanhui, LI Zixuan, WANG Zhenji, WU Minghui, JIAN Shenglong, WANG Guojie, LI Changzhong
Journal of Dalian Ocean University    2021, 36 (3): 406-413.   DOI: 10.16535/j.cnki.dlhyxb.2020-147
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To evaluate the influence of Zn 2+  on eckloni naked carp  Gymnocypris   eckloni  and screen the effective biomarkers, juvenile eckloni naked carp with body mass of (10±3) g was exposed to Zn 2+ prepared by ZnSO 4 ·7H 2 O at concentration of 1, 2, 5, 10 and 20 mg/L for determination of the LD 50  of Zn 2+ , and the expression of nuclear factor E2 related factor 2 (Nrf2), and genes of copper zinc superoxide dismutase (Cu/Zn-SOD), manganese superoxide dismutase (Mn-SOD), catalase (CAT) and glutathione peroxidase (GPx) in gill, kidney and liver tissues were detected by qPCR, the response levels of each gene heat map was analyzed in the three tissues by heat map, and change in the enzyme activities of SOD, CAT and GPx were measured by absorbance method. It was found that the median lethal dose (LD 50 ) of Zn 2+  was 5.0 mg/L in 24 h, 3.2 mg/L in 48 h, 2.5 mg/L in 72 h and 2.0 mg/L in 96 h with safe concentration of 0.2 mg/L. The mRNA expression levels of  Nrf 2,  Cu/Zn - SOD ,  Mn - SOD ,  CAT  and  GPx  and the activities of SOD, CAT and GPx were shown to be increased in gill, kidney and liver of eckloni naked carp within 96 h of Zn 2+  stress, with the different extent of increase. The heatmap analysis of gene expression showed that there was lower relative expression of  Nrf 2 than that in four downstream genes in the three tissues, especially in kidney and liver tissues. The findings indicated that the gene expression levels of  Nrf 2,  Cu/Zn - SOD ,  Mn - SOD ,  CAT  and  GPx  and the activities of related enzymes were correlated with the time of Zn 2+  stress and tissue specificity, and thus were used as potential biomarkers for early warning of water Zn 2+  pollution.
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Artificial propagation technology, and embryonic and early larval development of Schizothorax irregularis in Kizil River in Xinjiang
ZHAO He, HONG Jibiao, ZHAO Nianhua, HU Renyun, WEI Jie, NIE Zhulan,
Journal of Dalian Ocean University    2021, 36 (3): 414-422.   DOI: 10.16535/j.cnki.dlhyxb.2020-201
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In this study, key artificial propagation techniques including spawning season, sex identification, hormone injection and incubation methods were investigated in 1 380 individuals of  Schizothorax   irregulari  with body length of (152.31-271.25)mm and body mass of (102.17-265.31)g collected from Kizil River in Xinjiang in December 2017 and from January to December 2018 to accomplish farming and stock enhancement of the animals. A total of 35 pairs of 3 years old male and 4 years old female spawners at a ratio of female to male = 1∶2 was induced to spawn from late April to middle May at water temperature from 16.0 ℃ to 19.5 ℃ with an interval of 0.5 ℃ by injection of luteinizing hormone releasing hormone analogue (LHRH-A 3 )(3 mg/kg+4 mg/kg), dioxone maleate (DOM) (3 mg/kg+3 mg/kg) and human chorionic gonadotropin (HCG)(1 000 IU/kg). A total of 206 900 eggs and 141 200 postlarvae were obtained, with the optimum water temperature of 18.5 ℃ for induced spawn and 17.0-17.5 ℃ for incubation in the Southern of Xinjiang Uyghur Autonomous Region.  S.irregularis  had the eggs with diameter of (2.95±0.15)mm, and (3.53±0.12)mm after water absorption. The embryonic development was divided into seven stages: blastoderm, cleavage, blastula, gastrula, neuroblast, organogenesis and hatching. The embryos were hatched in 147 h 31 min at water temperature of (17.14±0.01)℃, with total accumulative temperature of 2 513.01 ℃·h. The newly hatched larvae had total length of (8.72±0.26)mm, staying at the bottom of the water and occasionally moved about in most of the period, even with heart beating and blood circulation. The development of the early larvae was clasified into four stages: eye pigmentation increasing period, body pigmentation increasing period, air bladder inflation period, and yolk sac exhausted completely. The larvae had completely exhausted yolk sac in 432 h, and the total length of (21.51±0.75)mm. The findings help to understand the developmental characteristics of embryos and early larvae of  S.irregularis , so as to further enrich the early life history data and provide scientific basis for resource protection and artificial propagation of  S.irregularis .
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Cloning，expression and functional identification of CD209 gene in Nile tilapia Oreochromis niloticus
LUO Guoling, WANG Xiaoqian, JIAN Jichang, LU Yishan, TANG Jufen, HUANG Yu,
Journal of Dalian Ocean University    2021, 36 (3): 374-382.   DOI: 10.16535/j.cnki.dlhyxb.2020-199
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 To further understand the molecular structure, expression characteristics and immune function of  CD 209 in Nile tilapia  Oreochromis   niloticus  ( OnCD 209)with body mass of (100±5)g, bioinformatics software was used to analyze  OnCD 209 amino acid sequence of the open reading frame (ORF) in Nile tilapia, and the relative expression of  OnCD 209 in healthy tilapia tissues including liver, spleen, gill and intestine post  Streptococcus   agalactiae  infection was detected by real-time fluorescent quantitative PCR (RT-qPCR), and  CD 209-pEGFP-N1 and  CD 209-pcDNA3.1 vectors were constructed to study the localization of  OnCD 209 molecular in 293T cells and its influence on NF-κB enzyme activity. The results showed that the ORF region of  OnCD 209 was found to be 1 383 bp, encoding 460 amino acids, and to have a carbohydrate recognition domain, accordance with the C-type lectin family. Multiple sequence alignment showed that  On CD209 was note conserved among species. Phylogenetic tree analysis revealed that  On CD209 were closely related to grassfish  Liparis   tanakae . Tissue expression showed that  OnCD 209 was detected in all tissues (brain, blood, skin, muscle, head kidney, intestine, gill, liver, spleen and thymus) with the maximal expression level in blood. The up-regulated expression of  OnCD 209 was observed in all detected tissues of Nile tilapia exposed to  S.agalactiae  infection in 6 h, then down-regulated at 12 h and 24 h，and then up-regulated at 48 h ( P <0.05). Subcellular localization analysis showed that  OnCD 209 was locatzed on the cytomembrane and the dual-luciferase reporter system indicated that  On CD209 significantly enhanced the NF-κB enzyme activity. The findings indicated that  OnCD 209 was involved in the immune response to bacteria and inflammatory response in Nile tilapia, which provides a theoretical basis for further study on the biological function of  OnCD 209.
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Prediction of dissolved oxygen and ammonia nitrogen concentrations in aquaculture environment based on PCA and GA-LM
YAO Qi, MIAO Xinying
Journal of Dalian Ocean University    2021, 36 (5): 851-858.   DOI: 10.16535/j.cnki.dlhyxb.2021-082
Abstract （6054）   HTML （5）    PDF（pc） （5451KB）（3500）       Save
To accurately predict two of the most important parameters, dissolved oxygen (DO) and ammonia nitrogen concentrations in aquaculture, aiming to solve the problems such as the determination of effective influence factors, prediction algorithm and network structure optimization, a prediction model of DO and ammonia nitrogen concentrations called GA-LM-PCA was proposed by combining the neural network (NN) algorithm of levenberg-marquardt (LM), genetic algorithm (GA) and principal component analysis (PCA). PCA was used to determine the influence factors which were decoupled and reduced in the dimension. The network architecture was optimized by GA for determination of the appropriate number of hidden layer nodes and weight values. LM was applied to train NN to improve the generalization ability and convergence speed. The performance of GA-LM-PCA was compared with that of GA-LM without PCA to verify the forecasting accuracy of the GA-LM-PCA, and the prediction effect of different quantity of influence factors was discussed. The comparison indicated that the predicted DO and ammonia nitrogen values using GA-LM-PCA were in good agreement with the measured data, with the mean absolute errors and the root mean square errors of 0.004 7, 1.872 7×10 -4  (DO), and 0.006 5， 9.428 7×10 -4  (ammonia nitrogen), indicating that GA-LM-PCA was more suitable for the occasion with a large number of influence factors. It is proved that the proposed model can be considered as an effective prediction tool for DO and ammonia nitrogen concentrations in aquaculture environment, especially for nonlinear systems with various complex factors.
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Effects of dissolved oxygen concentration on behavior, antioxidant enzyme activities and tissue structure of whelk Neptunea cumingii Crosse
ZHANG Qianhong, WANG Shaojun, TIAN Ying, WANG Luo, MAO Junxia, WANG Xubo, WANG Qingzhi, CHANG Yaqing, HAO Zhenlin
Journal of Dalian Ocean University    2022, 37 (4): 643-649.   DOI: 10.16535/j.cnki.dlhyxb.2021-309
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In order to explore physiological and ecological effects and to clarify the adaptation mechanism of whelk  Neptunea   cumingii  Crosse under different levels of dissolved oxygen (DO), the behavioral characteristics, histopathological damage in gill and olfactory tissue and antioxidant enzyme activity were investigated in the whelk with body weight of (85.3±9.3)g exposed to DO concentrations of 0, 2, 4, 6 and 8 (control) mg/L. The behavioral states of the whelk was divided into 4 types: normal state (less movement and long-term static adsorption), active state (short resting time, and long movement time), desorption state (foot edema), and death state (soft body part cannot be fully retracted into the shell). The whelk crawled actively and fed less when DO concentration was decreased, stopped feeding and death occurred at DO≤4 mg/L. Histological observation showed that the gap between gill filaments and the number of gill mucus cells were increased first and then decreased with the decrease in DO concentration. The top of gill filaments expanded, the respiratory epithelial cells fell off, and the surface cells sagged and formed folds, sometimes the gill filament was broken; the number of mucus cells was increased first and then decreased in osphradium with the decrease in DO concentration, without significant change in cell structure. The total antioxidant capacity (T-AOC) and activity of superoxide dismutase (SOD) in gill and hepatopancreas were shown to be decreased firstly, then increased and then decreased with the decrease in DO concentration, and the activity of CAT in gill to be increased first and then decreased. The activity of CAT in hepatopancreas was positively correlated with DO concentration. It was found that 6 to 8 mg/L of DO concentrations was the optimal or the whelk adapted to the hypoxic environment stress by changing behavior and related organizational structure, as well as regulating. The whelk was dead at DO≤4 mg/L for≥96 h.
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Recognition algorithm of marine ship based on improved YOLOv5 deep learning
ZHANG Xiaopeng, XU Zhiyuan, QU Sheng, QIU Wenxuan, ZHAI Zeyu
Journal of Dalian Ocean University    2022, 37 (5): 866-872.   DOI: 10.16535/j.cnki.dlhyxb.2022-104
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In order to improve the accuracy of marine ship recognition in multiple targets and foggy environments, a marine ship recognition model SE-NMS-YOLOv5 is proposed based on improved YOLOv5 deep learning. The model is combined with Dark channel defogging algorithm, SE(squeeze-and-congestion) attention mechanism module and improved non-maximum suppression model for training and testing of ship data sets. The results showed that in the ship recognition task, there was the accuracy of 90.6%, recall rate of 89.9% and SE-NMS-YOLOv5  F 1 value of 90.5%, and compared with YOLOv5 model, the detection effect is improved by 6.3%, 4.8% and 5.8%. Compared with YOLOv4, the model improved 19.1%, 19.0% and 19.3%. In foggy conditions, the accuracy, recall rate and  F 1 value of SE-NMS-YOLOv5-Dark channel model were 88.1%, 87.2% and 87.6%, compared with SE-NMS-YOLOv5 model, the detection results are improved by 13.8%, 13.3% and 13.5%, respectively. The findings indicate that the marine ship recognition method based on SE-NMS-YOLOv5 effectively solves the problem of low accuracy of marine ship detection on multiple targets and foggy conditions, and improve the overall effect of ship detection and recognition.
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Ocean target recognition model based on attention mechanism and Fast R-CNN deep learning
WEN Lili, SUN Miao, WU Man
Journal of Dalian Ocean University    2021, 36 (5): 859-865.   DOI: 10.16535/j.cnki.dlhyxb.2020-306
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In order to improve the detection ability of Faster R-CNN model for complex ocean targets, an improved Faster R-CNN model for multi-scale complex ocean targets is proposed by application of attention mechanism of adaptive scale. The model combines convolution network with SKNet network to enhance the feature extraction ability and effectiveness of the model. A total of 12 000 sample databases were established to detect four typical marine targets including ship, oyster raft, mangrove and coastline and recognize by using 91 satellite image assistant and UAV high-definition image. The comparison of improved Faster R-CNN model with the original model showed that feature extraction ability and target detection ability were significantly better than the original model, with the overall recognition accuracy of 87.1%, and with the maximal ship recognition accuracy (94.4%) among the four types of typical marine targets, while the mangrove recognition accuracy was found to be 75.1% because of its complex features and unclear boundary, although the improved model slightly increases the amount of calculation. The finding shows that the Faster R-CNN model with SKNet not only enhances the feature extraction ability of multi-scale complex targets, but also is more suitable for the detection and recognition of complex marine targets.
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Research progress of astaxanthin from Antarctic krill: a review
LIU Zhidong, MA Derong, CHEN Xuezhong, HUANG Hongliang, LIN Na, ZHANG Bianbian
Journal of Dalian Ocean University    2021, 36 (5): 866-874.   DOI: 10.16535/j.cnki.dlhyxb.2020-300
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Astaxanthin of Antarctic krill as a huge bioresource, still deeply undeveloped and unutilized marine living resources is a natural antioxidant with great antioxidant activities, and particularly, plays an important role in the body color change and the improvement of immunity of fish. In this article, the advances of preparation methods (solvent extraction method, enzymatic hydrolysis method, and supercritical carbon dioxide extraction), structure characteristics, bioactivities, detection methods (ultraviolet spectrophotometry, thin-layer chromatography, laser Raman spectrometry, high efficiency liquid chromatography and high performance liquid chromatography -tandem mass spectrometry) of astaxanthin from Antarctic krill are reviewed, and future suggestions on mechanism researches, key technologies and product developments of Antarctic krill astaxanthin are put forward. It is anticipated that contribute the deep research and utilization of Antarctic krill astaxanthin in the future.
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Correlation analysis between single nucleotide polymorphisms (SNPs) of GHRH gene and growth traits of tiger puffer Takifugu rubripes
WANG Ziyi, GOU Panpan, YANG Jin, MA Mingxing, YANG Shichen, LI Nan, QIU Xuemei
Journal of Dalian Ocean University    2022, 37 (1): 34-41.   DOI: 10.16535/j.cnki.dlhyxb.2021-205
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The purpose of this experiment was to investigate the effect of GHRH(growth hormone-releasing hormone)gene on the growth traits of tiger puffer  Takifugu   rubripes  and to provide reference for molecular assisted breeding.The sequences of  GHRH  gene were analyzed and aligned in tiger puffer whose body mass,body length,body height and other 10 growth-related traits were measured at the age of 6 months and 12 months after breeding by designed four pairs of PCR primers to cover the whole sequence of  GHRH  gene to screen the single nucleotide polymorphisms (SNPs).Subsequently,association analysis was performed between the SNPs and growth traits as well as linkage disequilibrium and diplotype analysis.The results showed that a total of seven SNPs sites were screened out,including C81T,G315C,C1083T,A1524G,G2107A,T2125C and G2256A,in which C81T,G315C and A1524G were significantly correlated with most growth traits.G2256A and T2125C,G207A and C083T were in linkage disequilibrium but not complete linkage.The diplotypes D4 and D5 had significantly higher mean body mass than the diplotype D3 did ( P <0 . 05).The three SNPs of C81T,G315C and A1524G were shown to be dominant loci with a positive effect on the growth of tiger puffer,and the diplotypes D4 and D5 were the dominant genotypes in 6 month old population,while the diplotype D5 was the dominant genotype in 12 month old population,which was preferred in the subsequent breeding process of tiger puffer.
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Effects of dietary stickwater hydrolysate and plant essential oils on growth performance,immunity,digestive enzyme activity and TOR related gene expression of juvenile turbot Scophthalmus maximus
HAO Tiantian, XU Cong, WANG Jiying, LIU Caili, SHEN Yubo, LI Baoshan, SUN Yongzhi, HUANG Bingshan
Journal of Dalian Ocean University    2022, 37 (3): 441-449.   DOI: 10.16535/j.cnki.dlhyxb.2021-216
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The purpose of this experiment is to investigate the dietary stickwater hydrolysate (SWH) and plant essential oil on growth performance,immunity,digestive enzyme activity and TOR related gene expression of juvenile turbot  Scophthalmus   maximus  fed low fish meal diets.Juvenile turbot with initial body weight of 37.67 g were reared in a closed water circulating system and fed diets containing 50% fish meal (D1,positive control),and containing 30% fish meal (D2,negative control),and 30% fish meal diets supplemented with 1% SWH (D3),0.02% plant essential oil (D4),and 1% SWH+0.02% plant essential oil (D5) with triplication at water temperature of (16±1)℃ for 8 weeks.The results showed that there were significant increase in weight gain rate,specific growth rate and protein efficiency ratio and significant decrease in feed conversion ratio in the turbot in D3 group ( P <0.05).The maximal activities of serum lysozyme was observed in the turbot in D5 group ( P <0.05),significantly higher than that in the D2 group ( P <0.05),without significant difference from D1 group( P >0.05).The turbot in D5 group had the minimal C3 content,significantly lower than that in other 4 groups( P <0.05).The maximal intestinal trypsin activity was found in the turbot juveniles in D3 group ( P <0.05),significantly higher than that in the D2 group( P <0.05),without significant difference from D1 group ( P >0.05).The maximal  TOR  mRNA expression level was observed in liver of fish in D3 group,significantly higher than that in the D2 and D1 groups ( P <0.05),with an opposite trend in 4 EBP 1 and 4 EBP 2 mRNA expression levels ( P <0.05).There was significantly lower cumulative mortality of juveniles exposed to  Vibrio   anguillarum  infection at a dose of 7.94×10 5  CFU/g for 48 h in D4 and D5 groups than that in D2 group ( P <0.05).It can be concluded that supplementation of 1% SWH led to significantly enhance the growth performance,trypsin activity,liver TOR related gene expression level of turbot,and that 0.02% plant essential oil to significantly enhance the ability of fish to resist  V.anguillarum  infection.However,the combination of 1% SWH and plant essential oil does not result in good effect instead of low weight gain,the mechanism of their interaction needs further research.
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Cloning of X-linked inhibitor of apoptosis protein XIAP gene and its response to stimulation in sea urchin Strongylocentrotus intermedius challenged with pathogenic microorganisms
LIU Shengmei, SHANG Fengqin, CHEN Yadong, CHANG Yaqing, WANG Xiuli, QIU Xuemei, LIU Yang
Journal of Dalian Ocean University    2022, 37 (4): 627-635.   DOI: 10.16535/j.cnki.dlhyxb.2021-303
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 To investigate the role of X-linked inhibitor of apoptosis protein (XIAP) gene in the natural immune system of sea urchin  Strongylocentrotus   intermedius , the cDNA sequence of  XIAP  gene was cloned using rapid amplification of cDNA ends (RACE) technique, and distribution in various tissues including tube foot, peristomial membrane, intestine, and gonad and the expression of  XIAP  gene were analyzed in coelomocyte in the sea urchin exposed to stimulation including lipopolysaccharide (LPS), peptidoglycan (PGN), polyinosinic-polycytidylic acid (Poly I:C),  Vibrio   fortis  and whole glucan particles (WGP) by real-time quantitative PCR. The results showed that the length of  XIAP  cDNA was 4 894 bp, with 5′ UTR of 459 bp, the open reading frame of 2 331 bp and the 3′ UTR of 2 104 bp, encoding a total of 776 amino acids with three BIR structural domains and one RING finger structural domain, with a predicted relative molecular mass of 86 960 and an isoelectric point of 5.96, as acidic protein.  XIAP  was expressed in all tissues examined, significantly higher expression in the ovary than that in the tube foot, coelomocyte, peristomial membrane, intestine and testis ( P <0.05), after stimulation with PGN, LPS, Poly I:C, WGP and  V.fortis .  XIAP  gene expression was up-regulated in coelomocyte significantly ( P <0.05), with the maximal values 12 h after PGN, LPS and Poly I:C stimulation, and with the maximal values 24 h after WGP stimulation and 6 h after  V.   fortis  stimulation. The findings indicated that the clonally obtained  XIAP  gene was involved in the immune response of the sea urchin and played an important role in its natural immunity.
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Analysis of expression patterns of three salinity-related microRNAs and predicted target genes in sea cucumber
WANG Yan, GAO Siqi, KUANG Qianyao, LIU Yining, TIAN Yi
Journal of Dalian Ocean University    2022, 37 (2): 212-220.   DOI: 10.16535/j.cnki.dlhyxb.2021-134
Abstract （5967）   HTML （12）    PDF（pc） （3246KB）（3182）       Save
Na + , Cl - , and K +  ion concentrations and sodium potassium ATPase activity were determined in the coelomic fluid of sea cucumber  Apostichopus   japonicus  with body mass of(16.38±1.27)g exposed to a salinity of 18 in 0, 6, 24 and 48 h.The results indicated that the sodium ion concentration increased significantly at 6 h after salinity stress( P <0.05), and then decreased with the stages of stress time.The lower concentrations of chloride and potassium ions were presented in the sea cucumber exposed to salinity stress than those of the control group( P <0.05), with the minimum at 6 h.The activity of sodium-potassium ATPase was lower than that of the control group at 6 h, with the minimum at 24 h.That miR-2011, miR-124 and miR-2010 formed a stable stem-loop structure based on the precursor sequences and mature sequences, which indicated that the three miRNAs were relatively conservative.Three differential expression in miRNAs(miR-2011, miR-2010 and miR-124)were presented and interacting target genes were obtained through miRNAs and target genes binding sites.Quantitative expression profiles showed that the miR-2011, miR-2010 and miR-124 were up-regulated in the sea cucumber exposed to salinity stress, compared to the maximal expression levels of miR-2011 and miR-2010 presented in 48 h under low-salt stress, 80 times and 24 times compared to control group(0 h), respectively.The target genes of miR-2011 were  PPM 1 L  and  PBK , the miR-2010 to  PPM 1 L , and the miR-124 to  EGF 3 and  IMPA 1.The findings indicate that the three miRNAs related to salinity genes are conservative and involved in regulation of salinity stress in sea cucumber.
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Detection of fish stocks by fused with SKNet and YOLOv deep learning
ZHAO Meng, YU Hong, LI Haiqing, XU Jingwen, CHENG Siqi, GU Lishuai, ZHANG Peng, WEI Sixue, ZHENG Guowei
Journal of Dalian Ocean University    2022, 37 (2): 312-319.   DOI: 10.16535/j.cnki.dlhyxb.2021-324
Abstract （5962）   HTML （1844084383）    PDF（pc） （4163KB）（3465）       Save
In order to solve the problem of low accuracy of fish detection caused by underwater imaging blur and distortion in actual aquaculture environment, a fish detection method(SK-YOLOv5)combining visual attention mechanism SKNet(selective kernel networks)and YOLOv5(you only look once)is proposed.In this method, UNet(convolutional networks for biomedical image segmentation)is firstly used to preprocess images to obtain clear fish images, and then SKNet is fused to Backbone end of YOLOv5 to form feature extraction network focusing on pixel-level information to strengthen the recognition ability of fuzzy fish.In this study, ablation test and model comparison test were carried out on underwater fuzzy fish swarming image data se to verify the effectiveness of SK-YOLOv5.The results showed that SK-YOLOv5 was effective in fish swarm detection task, and had recognition accuracy of 98.86% and recall rate of 96.64%, 2.14% higher and 2.29% higher compared with YOLOv5, respectively.Compared with XFishHmMp and FERNet with the maximal detection accuracy underwater target detection model, SK-YOLOv5 had the best detection effect, 5.39% higher in recognition accuracy, and 5.66% higher recall rate, and compared with FERNet, the recognition accuracy was improved by 3.59% and recall rate by 3.77%.The findings indicated that the fish detection of fusing SKNet and YOLOv5 can effectively enhence the identification ability of fuzzy fish, and improve the overall effect of fish detection and recognition.
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Effects of stocking density on growth performance, biochemical indices, water quality and economic benefits of giant freshwater prawn Macrobrachium rosenbergii in a greenhouse
NI Meng, CHEN Xuefeng, GAO Qiang, CHENG Haihua, HUA Jianquan, RONG Huanan, ZHOU Zhiming, YUAN Julin
Journal of Dalian Ocean University    2021, 36 (3): 423-429.   DOI: 10.16535/j.cnki.dlhyxb.2020-209
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To probe into the effects of different stocking densities on the water quality, growth and blood biochemical indices of giant freshwater prawn  Macrobrachium   rosenbergii  “Taihu No 2” and evaluate the optimal stocking density, giant freshwater prawn with an initial body mass of (0.61±0.05)g were randomly reared in nine 2 000 m 2  plastic ponds in a greenhouse at three stocking densities: low density (LSD， 37.5 ind./m 2 ), middle density (MSD, 45.0 ind./m 2 ) and high density (HSD, 60.0 ind./m 2 ) with triplication for 60 days. It was found that there were significantly higher ammonia nitrogen and nitrite nitrogen levels in HSD group than those in LSD and MSD groups at the end of the experiment ( P <0.05). There were significantly lower survival rate, final body mass, final body length, length of carapace and specific growth rate in HSD group than those in LSD and MSD groups ( P <0.05). However, food conversion ratio was found to be significantly higher in HSD group than those in LSD and MSD groups ( P <0.05), without significant difference between LSD group and MSD group( P >0.05). The yield was shown to be increased with the increase in stocking density, significantly higher in MSD and HSD groups than that in LSD group ( P <0.05), and the maximal output and profit were observed in MSD group. The giant freshwater prawn in HSD group had significantly higher blood glucose level and alanine transaminase activity than those in LSD and MSD groups did( P <0.05), with significantly lower total protein and globulin levels in HSD group than those in LSD and MSD groups ( P <0.05). The findings indicated that stocking density of 45.0 ind./m 2  was of the appropriate giant freshwater prawn culture in the greenhouse.
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Effects of compound probiotics on reproductive performance, physiological indices and larval survival rate in largemouth bass Micropterus salmoides
WANG Saisai, ZHU Lifei, LI Rongni, SHI Dongjie, SUN Yansheng, ZHANG Xin
Journal of Dalian Ocean University    2021, 36 (6): 959-965.   DOI: 10.16535/j.cnki.dlhyxb.2020-323
Abstract （5950）   HTML （9）    PDF（pc） （648KB）（3510）       Save
In order to study effects of compound probiotics on the delayed reproductive performance, physiological indices and larval survival rate in largemouth bass  Micropterus   salmoides , 150 pairs of broodstock with body mass of 550-665 g in female and 500-573 g in male were randomly reared in 15 tanks of each 5.0 m×2.7 m×1.0 m, and fed 5 diets supplemented with 0, 0.1%, 0.3%, 0.5% and 0.7% of compound probiotics in the basic diet with 3 replicates at water temperature of below 17.5 ℃ for 30 days in early July. Then, 3 d after rearing, the largemouth bass broodstocks were induced to spawn at water temperature warming to 21.5-22.5 ℃ by hormone injection. The results showed that the gonado-somatic index (GSI), fecundity and relative fecundity of female were increased gradually with the increase in compound probiotics dose, with the peak in 0.5% group, without significant difference in GSI, fecundity and relative fecundity among the other test groups ( P >0.05). There were higher fertilization rate, hatching rate and larval survival rate in first batch in 0.3% and 0.5% groups than those in other groups, with significantly higher survival rate in 0.5% group than that in control group and 0.1% group( P <0.05). There was gradual increase in activities of alkaline phosphatase (AKP) and acid phosphatase (ACP) in liver of female largemouth bass in groups before spawning, and higher than those after spawning( P <0.05), with the peak AKP and ACP activity in the 0.5% group, without significant difference in the activity of total superoxide dismutase (T-SOD) in liver of female fish among different groups before spawning( P >0.05), significantly higher activity of T-SOD in plasma in 0.3% and 0.5% groups than those in other groups ( P <0.05). The significant improvement of the larval survival rate and enhancement of the activities of AKP and ACP in the liver and T-SOD activity in plasma were observed in the female fish in 0.5% group. The finding provides theoretical basis for the application of compound probiotics in the delayed breeding of largemouth bass.
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Histopathological observation of gas bubble disease in Pacific white leg shrimp Litopenaeus vannamei
QI Ruirong, TANG Shaolin, ZHANG Jipeng, CUI Longbo, MA Jiahao
Journal of Dalian Ocean University    2021, 36 (6): 952-958.   DOI: 10.16535/j.cnki.dlhyxb.2020-334
Abstract （5948）   HTML （9）    PDF（pc） （16523KB）（3531）       Save
In order to probe Pacific white leg shrimp  Litopenaeus   vannamei  with gas bubble disease naturally occurring and with body length of (6.3±1.5)cm in an earthen pond, histopathological changes were primarily investigated by field microscopy, bacterial isolation and culture, PCR detection and histological techniques. The results showed that the diseased shrimp had slightly red body in color, and white abdominal muscle segments. The air column and bubbles were observed in the appendages, gill, antennae, and the muscles of cephalothorax. The pathological features of the diseased tissues were characterized by bubbles in muscle, eyes, gills, hepatopancreas, antennal and heart tissues. The bubbles were concentrated in the middle and posterior segments of the muscle, also found in the dorsal ventral vessels and branchial axis vessels. There were more and bigger bubbles in the shrimp with obvious bubbles in clinical than the samples with invisible bubbles. The bubbles in the gill became more and bigger with dissolved oxygen concentrations increase in dissolved oxygen varying from 4.15 mg/L to 15.06 mg/L (saturation of 56%-293%); the eyes showed vacuolation, one side eye lesions were slightly heavier at low level of dissolved oxygen, whereas vacuolization became serious when dissolved oxygen value was increased. meanwhile serious vacuolization were observed in both sides of the eye at high level of dissolved oxygen. Findings indicated that the above phenomena or pathological characteristics were diagnosed as gas bubble disease of Pacific white leg shrimp.
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Prokaryotic expression and acetylation identification of phosphomethylpyrimidine synthase (ThiC) in Vibrio alginolyticus
WANG Xudong, FAN Chenlong, DING Yu
Journal of Dalian Ocean University    2022, 37 (3): 435-440.   DOI: 10.16535/j.cnki.dlhyxb.2021-148
Abstract （5943）   HTML （161）    PDF（pc） （3977KB）（3310）       Save
To understand whether there is acetylation of phosphomethylpyrimidine synthase (ThiC) in pathogenic  Vibrio   alginolyticus ,the target gene  ThiC  was amplified via PCR basing on the genome of  V.alginolyticus  HY 9901.The prokaryotic expression vector pET-28a- ThiC  were constructed,which was successfully expressed in  Escherichia   coli  BL21 by induction,and its expression conditions were optimized.Then,the protein expression and acetylation level were analyzed by SDS-PAGE and Western blot.The results showed that the  ThiC  gene had length of 1 941 bp,and that the recombinant  Escherichia   coli  BL21 was expressed as the recombinant protein(72 500).The optimal expression of recombinant protein was under conditions of 0.1 mmol/L IPTG for 3 hours at 37 ℃.Western blot results revealed that ThiC was acetylated protein,and there was no deacetylation in vitro.In conclusion,the recombinant expression strain for  V.alginolyticus  ThiC was successfully constructed,ThiC was acetylated protein,and there was no deacetylation in vitro.The findings lay the foundation for studying the post-translational regulation mechanism of vitamin nutrition of  V.alginolyticus .
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Effects of pathogen Vibrio harveyi infection on DNA methylation of IL-6 gene in tiger puffer Takifugu rubripes
WANG Chenshi, HUANG Xindi, CUI Xiaoyu, NI Ping, YE Shigen, WANG Hua, GAO Dongxu, LEI Wei
Journal of Dalian Ocean University    2022, 37 (2): 221-226.   DOI: 10.16535/j.cnki.dlhyxb.2021-115
Abstract （5938）   HTML （11）    PDF（pc） （3591KB）（3243）       Save
To investigate effect of pathogen  Vibrio   harveyi  infection on DNA methylation of the interleukin-6(IL-6)gene in tiger puffer  Takifugu   rubripes , tiger puffer with body mass of(100.5±10.8)g was exposed to clean sea water(control group)and  V.harveyi (10 7  cfu/mL)(treatment group)for 12 h and then transferred to clean sea water without pathogens for 7 d when histological changes,and the relative expression level of  IL -6, and DNA methylation levels and patterns in the  IL -6 promoter region were determined in the spleen of tiger puffer.The results showed that there was a large degree of cell necrosis in the diseased group, and no obvious necrotic areas were found in the non-diseased group.There was significantly higher mRNA level of  IL -6 in the spleen in the diseased group than that in the control and non-diseased groups( P <0.05), without significant difference between the control and non-diseased groups( P >0.05).The methylation level of  IL -6 was shown to be significantly higher in the spleen of the non-diseased group than that in the diseased group( P <0.05).These findings indicated that tiger puffer chalenged with  V.harveyi  showed different degrees of disease resistance, which might be involved in significantly different methylation states at the  IL -6 promoter.
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Extraction and structural analysis of isolated proteins from laver Porphyra haitanensis
TAO Fengting, PAN Chuang, QI Bo, HU Xiao, ZHAO Yongqiang, YANG Xianqing, YANG Lili
Journal of Dalian Ocean University    2022, 37 (5): 850-857.   DOI: 10.16535/j.cnki.dlhyxb.2021-295
Abstract （5934）   HTML （6）    PDF（pc） （3756KB）（3019）       Save
To understand effect of ammonium sulfate on the structural property and antioxidant activity of the isolated proteins during separation, the proteins were precipitated by using ammonium sulfate with gradient saturation from laver  Porphyra   haitanensis . The physicochemical, structural and spectral properties and differences in their antioxidant activities of target proteins were analzed. The results showed that there was the maximal extraction rate of up to 55.28% by ultrasonic-assisted phosphate buffer treatment. The crude extract of laver  P.haitanensis  (CEPh) then was precipitated by ammonium sulfate with different saturations and the protein was mainly precipitated at 40% to 60% saturation. UV absorption showed that phycobiliproteins were precipitated at ammonium sulfate saturation varying from 30% to 50%. When the saturation exceeded 50%, however, two non-protein absorption peaks were appeared at 773 and 1 155 cm -1  in the infrared spectra. The Circular Dichroism spectra revealed that the α-helix structure was the main protein structure of the laver, the protein structure of 40%-PhPI being the most orderly. SDS-PAGE indicated that low saturation (10% to 30%) of ammonium sulfate led to significantly improve the precipitation of proteins with relative molecular mass of 55 000, 20 000 and 18 000. The antioxidant tests revealed that the isolated proteins obtained with ammonium sulfate at different saturation had certain antioxidant activities, but with great differences. The finding provides ideas for the extraction method of the laver protein and the selection of saturation range of ammonium sulfate precipitation method, which provides support for the antioxidant activity of the laver protein.
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Comparison of embryonic development and growth of larvae and juveniles between all-female and self-bred mandarin fish Siniperca chuatsi
GONG Wanda, SONG Wen, ZHONG Lin, LIANG Xiao, WANG Shourong, ZENG Kewei
Journal of Dalian Ocean University    2022, 37 (1): 26-33.   DOI: 10.16535/j.cnki.dlhyxb.2021-092
Abstract （5925）   HTML （10）    PDF（pc） （2870KB）（3235）       Save
The fertilized eggs were obtained by artificial reproduction of all-female mandarin fish  Siniperca   chuatsi  and self-bred mandarin fish,and incubated at water temperature of 26-28 ℃.The total length and body mass were measured from 5 day old postlarvae to 60 days old juveniles of all-female and self-bred mandarin fish reared in a cement tank of 2 m×2 m×1.5 m in 5-7 days interval to compare the embryonic development and growth rate of all-female and self-bred mandarin fish.The embryo development of the offsprings of all-female and self-bred mandarin fish were observed and compared,and the characteristics of seven successive development stages of the fertilized eggs were described as following:fertilization,cleavage,blastula,gastrula,neuroblast,organogenesis and hatching stage.The results showed that it took 39 h 12 min from fertilization to hatching in all-female mandarin fish and 38 h 44 min in self-bred mandarin fish at same water temperature and incubation mode,with basically the same embryonic development characteristics in all stages.There was significant differences in growth in 21 days old all-female and self-bred mandarin fish afterwards ( P <0.05).The growth equation was expressed as  W =0.016 L 2.971 ( R 2 =0.991)in all-female mandarin fish,indicating that the growth rate was generally uniform in the larval and juvenile stages.The growth equation was described as  W =0.020 L 3.008 ( R 2 =0.991)in self-bred mandarin fish,indicating that the growth of body mass was better than that in total length at this stage.The findings indicated that the all-female and self-bred mandarin fish had primarily the same embryonic development time and characteristics,and that the all-female mandarin fish had better growth rate than the self-bred mandarin fish did.
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Spatio-temporal characteristics and relationship with environmental factors of zooplankton community structure in the Beiluo River basin
BAI Haifeng, KONG Feihe, WANG Yirui, SONG Jinxi, CAO Yelin, JIANG Xiaohui
Journal of Dalian Ocean University    2021, 36 (5): 785-795.   DOI: 10.16535/j.cnki.dlhyxb.2021-047
Abstract （5924）   HTML （2）    PDF（pc） （4260KB）（3554）       Save
To understand the status and dynamics of zooplankton community structure in the Beiluo River basin, we collected zooplankton samples in 14 sections by plankton net in wet season of 2017(from September to October), and dry season of 2018(from April to May). The results showed that a total of 60 zooplankton species were recorded, with dominance groups of rotifers and protozoa, accounting for 86.7% of the total number of species. The dominant species of zooplankton throughout the year were  Keratellacochlearis ,  Polyarthradolichopteria ,  Proalessordida , and nauplius, with obvious changes and great difference in the dominant species in different seasons, with annual average zooplankton density of 36.77 ind./L and zooplankton biomass of 46.341 μg/L. The density cluster analysis showed that zooplankton sampling sites were divided into three groups in dry season,and two groups in wet season. The Shannon-Weiner diversity index of zooplankton in the Beiluo River basin varied from 2.56 to 3.47, the Pieluo evenness index varied from 0.71 to 0.90, and the Margalef richness index varied from 1.01 to 2.88. The Canonical correspondence analysis indicated that altitude and pH were the most important environment factors affecting zooplankton community in dry season, and the community structure of zooplankton in wet season were primarily affected by total dissolved solids, water temperature, channel width and phytoplankton. The findings indicated that the diversity of zooplankton was good, the structure of zooplankton communities was stable and the water quality as whole was in the state of medium pollution in the Beiluo River basin, which can provide reference with environmental management and water resources development and utilization in the Beiluo River basin.
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Effects of partial fish meal substitution by fish peptide and protease on growth, intestinal digestive enzymes and intestinal microflora of Pacific white shrimp Litopenaeus vannamei
ZHU Yuzheng, SHEN Liang, GUO Ran, JING Bingyan, LIANG Beining, GAO Jiapeng
Journal of Dalian Ocean University    2022, 37 (5): 756-763.   DOI: 10.16535/j.cnki.dlhyxb.2021-194
Abstract （5919）   HTML （9）    PDF（pc） （2160KB）（3157）       Save
In order to reveal that enzymatic peptide and protease replace 5% fish meal in the diet of Pacific white shrimp  Litopenaeus   vannamei , the effects of partial fish meal substitution by enzymatic peptide and protease on the growth, digestive indices and intestinal flora of Pacific white shrimp was investigated. Pacific white shrimp juveniles with initial body weight of (0.32±0.01)g were reared in an aquarium (40 cm×50 cm×60 cm)and fed basic diet (control group), and diet containing 5% fish meal replaced by 5% peptide (group EP) and by 0.3% protease (group PR) at water temperature of 28 ℃ for 56 d with three repetitions. The results showed that there were higher final body weight and weight gain rate in the shrimp in EP and PR groups than those in the control group, with significant differences in hepato-somatic ratio and dressing rate ( P <0.05). The plasma glucose, total cholesterol and triglyceride levels were shown to be significantly higher in EP and PR groups than those in control group ( P <0.05). The shrimp in EP and PR groups had higher activities of lipase, pepsin and protease than the shrimp in control group did ( P <0.05). Shannon index in enzymatic peptide and protease groups was higher than that in control group, Simpson index in protease group was significantly lower than that in control group, and that in peptide group was significantly lower than that in protease group ( P <0.05). At the phylum level, the number of Proteobacteria and Actinobacteria in group enzymatic peptide was higher than that in control group and protease group. At the class level, in enzymatic peptide and protease groups the Alphaproteobacteria of Proteus was lower than that in control group, and Gammaproteobacteria in enzymatic peptide and protease groups were higher than in control group and enzymatic peptide group, and Verrucomicrobiae was higher than in control group and protease group. At the genus level, it can be seen that the proportion of  Rhodobacteraceae _unclassified in enzymatic peptide and protease groups was higher than that in the control group, with the large difference, and little difference among  Flavobacterium _unclassified groups. The findings indicated that the addition of enzymatic peptide and protease in the diet improved the growth performance of Pacific white shrimp, with positive impact on digestive indices and intestinal structure, and that enzymatic peptide and protease were used as a new resource to reduce the addition of fish meal in shrimp formula feed.
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Effects of different temperature stress on gill apoptosis of medaka Oryzias latipes
HU Linghong, WANG Ying, WANG Huamin, CHEN Liangbiao
Journal of Dalian Ocean University    2021, 36 (6): 929-936.   DOI: 10.16535/j.cnki.dlhyxb.2021-053
Abstract （5917）   HTML （7）    PDF（pc） （8695KB）（3345）       Save
In order to explore the effect of different temperature stress on gill apoptosis of medaka  Oryzias   latipe , Japanese HdrR strain of medaka was exposed to 35 ℃ and 40 ℃ (2 high temperature groups), 10 ℃ and 4 ℃ (2 low temperature groups) and 26 ℃ (1 normal temperature group), at a rate of 1 ℃/h warming or cooling. Then the degree of apoptosis and ROS content in gill cells of the medaka exposed to different temperature stress for 12 h were determined by TUNEL staining and flow cytometry and the expression levels of pro-apoptotic genes  caspase  3,  caspase  9,  p 53 and anti-apoptotic genes  caspase 1 and  bcl 2 were detected by qPCR. The results showed that the apoptosis phenomenon was observed in medaka gill cells in 12 h at 35 ℃ and 12 h at 40 ℃ under high temperature stress compared with normal temperature (26 ℃) ( P <0.05), with cell apoptosis rate of 21.78% and the most significant apoptosis in 40 ℃ for 12 h ( P <0.01). The content of ROS was shown to be increased with temperature rising significantly ( P <0.05), and the expression levels of the apoptosis promoting genes  caspase 3,  caspase 9 and  p 53 were significantly elevated with temperature rising ( P <0.05), while the expression levels of the suppression of apoptosis gene  caspase 1 and  bcl 2 were significantly reduced accordingly ( P <0.05). The gill cells of medaka also showed apoptosis under low temperature stress of 10 ℃ for 12 h and 4 ℃ for 12 h ( P <0.05), with apoptotic rate of 24.79% at 4 ℃ for 12 h ( P <0.01). The expression levels of the apoptosis promoting genes  caspase 3,  caspase 9 and  p 53 were not increased significantly at 10 ℃ for 12 h ( P >0.05), while the expression levels of the apoptosis promoting genes were increased significantly at 4 ℃ for 12 h ( P <0.01) compared with normal temperature (26 ℃) ( P <0.05). The expression levels of anti-apoptotic genes  caspase 1 and  bcl 2 showed a trend of first decreasing and then increasing as the warming temperature. In conclusion, both high temperature and low temperature stresses can cause oxidative stress to some extent, produce a large amount of ROS, and induce the gill tissue apoptosis. The degree of cell apoptosis in the gill under extreme temperature stress affects the survival time of fish. The finding provides foundation for the research of the lethal mechanism of fish under extreme temperature stress.
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Effects of different application methods of clove oil on anesthetic effect of red swamp crayfish Procambarus clarkii
JIANG Jingjing, ZHANG Chengfeng, HAN Caian, TIAN Can, ZHANG Ping, XU Zenghong, GAO Yang, SU Shengyan, TANG Yongkai
Journal of Dalian Ocean University    2022, 37 (5): 817-822.   DOI: 10.16535/j.cnki.dlhyxb.2021-244
Abstract （5914）   HTML （127）    PDF（pc） （1794KB）（3086）       Save
In order to reduce the stress damage of red swamp crayfish  Procambarus   clarkii  caused by human operation during the actual production and scientific research, small red swamp crayfish with body weight of (6.17±0.20)g were bathed in and sprayed with the mixture of clove oil and ethanol solution at a volume ratio of 1∶1.5 at a dose of 1, 2, 4, and 8 g/L and 8, 10, 16, and 20 g/L, respectively. Large red swamp crayfish with body weight of (29.54±0.30)g were bathed in and sprayed with the same mixture of clove oil and ethanol solution at a dose of 10, 16, 20, and 24 g/L and 8, 10, 16, and 20 g/L, respectively for anesthesia. The results showed that with the increase in anesthetic agent concentration, the anesthetic time was found to be shortened and the recovery time to be prolonged, with the appropriate concentrations of 8 g/L in small size crayfish and 20 g/L in large size ones, and the appropriate concentrations of 4 g/L for spray anesthesia and 16 g/L for bath. The red swamp crayfish with spraying anesthesia showed cheliped behavior that was used as a criterion to divide anesthesia into four stages. Significant decrease in oxygen consumption and anesthetic effect was observed in both methods of anesthesia ( P <0.05). There were significantly lower oxygen consumption rate and SOD and CAT enzyme activities in the red swamp crayfish with spraying anesthesia than those in the crayfish with immersion anesthesia ( P <0.05). The findings indicated that both spraying and immersion anesthesia were used for red swamp crayfish anesthesia, especially surface spraying anesthesia being featured by significant decrease in the oxygen consumption rate and less stress damage to individual gill tissue, and better anesthesia effect compared with the immersion anesthesia.
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Prokaryotic expression, purification and immunogenicity of LrrG protein of Streptococcus agalactiae based on codon optimization
CHEN Zhiting, KE Xiaoli, CHEN Gang, HUANG Lifang, LIU Zhigang, LU Maixin
Journal of Dalian Ocean University    2021, 36 (6): 920-928.   DOI: 10.16535/j.cnki.dlhyxb.2021-012
Abstract （5882）   HTML （17）    PDF（pc） （6274KB）（3492）       Save
In order to improve the supernatant expression of the recombinant protein leucine-rich repeat sequence (LrrG), the pCzn1- LrrG  recombinant expression vector was constructed and transfected into the competent cell BL21 (Plys). First, according to the codon preference of  Escherichia   coli , the whole  LrrG  gene sequence was artificially synthesized and inserted into the expression vector through double enzyme digestion. The optimized recombinant plasmid pCzn1- LrrG  was transfected into competent cells for prokaryotic expression. The supernatant recombinant protein LrrG obtained by lysis and purification had the optimized  LrrG  gene fragment of 2 286 bp via PCR amplification. The recombinant plasmid pCzn1- LrrG  constructed by double enzyme digestion contained 2 fragments of about 4 400 bp and 2 286 bp. The sequenced recombinant vector was completely consistent with the optimized gene sequence, and the encoded amino acid sequence remained unchanged. The SDS-PAGE and western blot revealed that the relative molecular mass of the LrrG recombinant protein was about 108 000, showing GBS antigenicity. After purified by affinity chromatography, the expression quantity of LrrG recombinant supernatant protein in  Escherichia   coli  BL21 (Plys) was increased by 2.2-3.8 times compared to that of the original type. Moreover, the optimized LrrG recombinant protein supplied a 61.54%-69.23% RPS against GBS infection in tilapia, indicating that the codon optimization effectively improved the expression level of LrrG recombinant protein in  E. coli, and the optimized LrrG recombinant protein still maintained the original immunogenicity. The findings laid a foundation for the preparation and application of the genetic engineering vaccine based on the surface protein of  S.agalactiae .
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Changes in community structure and trophic level characteristics of fisheries organisms in Sanmen Bay waters
YU Songli, WANG Yongxue, HAN Xiaofeng, ZHANG Yihan, LAI Hongyun, ZHANG Kai, ZHANG Liyuan, SHUI Bonian
Journal of Dalian Ocean University    2021, 36 (3): 478-487.   DOI: 10.16535/j.cnki.dlhyxb.2020-133
Abstract （5878）   HTML （15）    PDF（pc） （2956KB）（3529）       Save
To reveal the current situation and changes in community characteristics of fisheries organisms in Sanmen Bay waters, the relative importance index, resource density, species diversity, ABC curve, cluster analysis, non-metric multi-dimensional scale analysis, niche width and trophic level structure were used to probe into the fisheries community in 20 sampling sites during a fisheries resource survey by bottom trawls in spring (April), summer (July), autumn (October) and winter (December) of 2018. The results showed that there was the maximal number of fishery species in summer (84 species) and the minimum in winter (42 species), 3 dominant species in spring, 6 ones in summer, 6 ones in autumn and 2 ones in winter. The maximal number density and weight density of fishery biomes were observed in summer, and the minimum in winter. There were the maximal mean value of Shannon-Wiener diversity index and mean evenness index in autumn and the minimum in winter. The maximal mean richness index was found in summer and the minimum in winter. The ABC curve showed that moderate disturbance was observed in the four seasons of 2018. The analysis of community structure revealed that the seasonal differences in fisheries communities were large, and that the niche widths of fishery biomes were varied greatly in different seasons. Overall, number and biomass of the species in the third trophic levels were dominant, while the number and biomass of the species in the second and fourth trophic levels were relatively minor, with the weak stability of the structure of the fishery biological community. The findings indicated that the implementation of the fishery management system was achieved certain results, and the number of fishery biological species in Sanmen Bay waters was recovered to a certain extent, but it still suffered from the interference of human factors including high fishing pressure, nuclear power plant and breeding pollution, and the decline of resources was been effectively restricted. Therefore, it is urgent to carry out the reform of fishery resource restoration strategy and to strengthen the restoration of fishery resources and marine ecology in Sanmen Bay.
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