Journal of Dalian Ocean University

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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

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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

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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

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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

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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

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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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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

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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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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

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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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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

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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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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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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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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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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

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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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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

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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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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

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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 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）

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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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Research progress on nutritional characteristics and bioactivities of oysters: a review

ZHANG Chaohua

Journal of Dalian Ocean University 2022, 37 (5): 719-731. DOI: 10.16535/j.cnki.dlhyxb.2022-243

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Oyster as a kind of marine shellfish with high nutrition, functional health care and medicinal value has great potential in the application of functional food production. Oysters are high in protein, rich in glycogen polysaccharides, zinc and other mineral elements, and have high nutritional value. Oyster peptides and polysaccharides have been proved to have a wide range of functional activities, such as anti-oxidation, anti-inflammatory, antihypertensive, anti-fatigue, anticoagulation, anti-tumor, and anti-liver injury. However, at present, the development and application of oysters in nutrition and functional food are very limited. This paper reviews the characteristics and nutritional value of oyster nutritional composition, as well as the research progress on the role of peptides, polysaccharides, zinc and other active functional components. In view of the research problems and development status of oyster in this field, the strategic prospect of research and development in preparation technology, functional activity improvement, factor deep mining, steady state, interaction and synergy mechanism is put forward, in order to provide reference for the further development and deep utilization of oyster resources.

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Expression analysis and preparation of recombinant protein of T-cell immunoglobulin and mucin-domain-containing molecule 4 (TIM-4) gene from oblique grouper Epinephelus coioides

LI Jinze, TANG Jufen, HUANG Yu, JIAN Jichang, SHI Gang, CAI Jia

Journal of Dalian Ocean University 2022, 37 (3): 403-410. DOI: 10.16535/j.cnki.dlhyxb.2021-172

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In order to study the role of T-cell immunoglobulin and mucin-domain-containing molecule 4 (TIM-4)gene in the immune response of oblique grouper Epinephelus coioides ,protein-coding regions of the oblique grouper was obtained using polymerase chain reaction (PCR),and the structural characteristics of its protein coding region were analyzed by bioinformatics.The tissue distribution of TIM -4 gene were detected by real-time fluorescence quantitative PCR (qPCR).The expression profiles of TIM -4 gene was investigated in spleen (GS) cells exposed to lipopolysaccharide (LPS) and polyinosinic acid (Poly I:C) stimulation.The recombinant plasmid TIM -4-4T was constructed,and transformed into Escherichia coli BL21 (DE3) for inducing prokaryotic protein expression.The results showed that the protein coding region (GenBank accession number:MZ465580) of TIM -4 was 702 bp,encoding 234 amino acids protein containing three functional domains,a V-Type(IGV)domain,a BTK domain and a PRY domain.qPCR results showed that TIM -4 was expressed in all examined 10 tissues of oblique grouper,with the maximal expression in stomach ( P <0 . 05),and the minimal in spleen.There was significantly lower expression of TIM -4 in GS cells exposed to LPS stimulation,and significantly increase in GS cells exposed to Poly I:C stimulation ( P <0 . 05).The SDS-PAGE analysis revealed that the TIM-4 fusion protein had relative molecular weight of about 25 100.The optimal expression TIM-4 recombinant protein were inducing with 0.4 mmol/L IPTG at 37 ℃ for 6 h.The findings indicate that TIM -4 may be involved in anti-infectious immunity of oblique grouper,which provides a theoretical basis for further study on the biological function of TIM -4.

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Effects of sodium butyrate on growth, physico-chemical indices and intestinal structure of common carp Cyprinus carpiofed high dietary levels of carbohydrate or lipid

ZHANG Yuanyuan, Lü Shuo, LU Zhengyi, CUI Pei, SUN Jinhui, QIAO Xiuting, CHENG Zhenyan

Journal of Dalian Ocean University 2022, 37 (5): 747-755. DOI: 10.16535/j.cnki.dlhyxb.2021-189

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A feeding trail was conducted to investigate the effects of sodium butyrate on growth and health of common carp Cyprinus carpio fed high dietary levels of carbohydrate or lipid. Common carp with initial body weight of (44.74±0.34)g were reared in an indoor recirculating culture system (80 cm×60 cm×50 cm) and fed basic diet (control group, group D0), containing 7.5% dextrin (high-sugar group, HCD, group D1), containing 10% lipid (high-lipid group, HLD, group D2), basic diet+0.5% sodium butyrate (group SB, group D3 ), high sugar group+0.5% sodium butyrate (group D4) and the high lipid group+0.5% sodium butyrate (group D5) at water temperature of 26.5 ℃ to 30.5 ℃ for 70 d. Then, the growth performance, physico-chemical indices and intestinal structure of common carp were analyzed. The results showed that the common carp fed diets with high levels of carbohydrate or lipid had poor growth performance compared with the control group, without significant difference ( P >0.05). The growth of common carp was affected significantly by addition of sodium butyrate. There were significantly higher final body weight, weight gain rate and specific growth rate in the common carp fed the diets containing sodium butyrate than those in the common carp in the control group, increasing by 11.28%, 25.48% and 14.89%, respectively, and the feed conversion ratio was significantly reduced by 8.72% ( P <0.05). The feed conversion rate and the body lipid content was shown to be significantly higher in fish fed diets containing high level of lipid than those in other groups ( P <0.05), however, the addition of sodium butyrate did not significantly affected the body lipid ( P >0.05). Compared with the control group, the contents of serum glucose (GLU) and serum total cholesterol (T-CHO) were increased significantly after feeding high levels of carbohydrate, however, serum GLU and TG decreased significantly while serum T-CHO increased significantly after adding sodium butyrate ( P <0.05). The activities of serum catalase (CAT) and total superoxide dismutase (SOD) were found to be increased significantly by 24.45% and 18.96% ( P <0.05), and the content of serum malondialdehyde (MDA) was decreased significantly by 13.53% after supplemented with sodium butyrate ( P <0.05). High dietary levels of carbohydrate or lipid led to significantly increase in the length of hindgut villi compared with the control group ( P <0.05). The length of anterior, middle and posterior intestinal villi was increased significantly in the fish fed diets with sodium butyrate by 19.51%, 27.68% and 26.59%, respectively, compared to those in the control group ( P <0.05). In conclusion, the addition of sodium butyrate to diets with high levels of carbohydrate and lipid can lead to improve the growth performance of common carp, which showed positive impact on the physical and chemical indices of serum and intestinal structure.

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Preparation and characterization of thermoresponsive starch ether/sodium alginate composite hydrogels

PANG Zijian, XU Yuan, JIANG Shuo, SUN Meng, JIANG Qian, SUN Wei, ZHA Xiaohan, SHANG Yue, DAI Mingyun, LIU Ying, TIAN Ye

Journal of Dalian Ocean University 2022, 37 (3): 505-512. DOI: 10.16535/j.cnki.dlhyxb.2021-176

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A thermoresponsive hydrogel composed of 2-hydroxy-3-isopropoxypropyl starch (HIPS) and sodium alginate (SA) was synthesized via cross-linking with hybrid crosslinkers including ethylene glycol diglycidyl ether (EDGE) and calcium chloride (CaCl 2 ).Attenuated total reflection infrared spectroscopy (FT-IR) was used to confirm the occurrence of crosslinking.The HIPS/SA composite hydrogels were investigated for their porous architecture and thermoresponsive property using scanning electron microscopy (SEM).The reaction temperature and reaction time significantly affected the swelling rate of HIPS/SA composite hydrogels ( P <0.01).The optimum HIPS/SA hydrogel synthesis was observed under conditions of HIPS concentration of 6.5% (2 g),SA concentration of 4.5% (2 g),NaOH of 300 μL,EDGE of 300 μL,reaction temperature of 55 ℃ and reaction period of 3 h,with the hydrogel swelling ratio of 44.20 under above conditions.It was found that the HIPS/SA hydrogel possessed desirable thermoresponsive property,and the swelling rate (SR) of hydrogel was sharply decreased when the temperature was higher than volume phase transition temperature (VPTT) 34.9 ℃.The HIPS/SA hydrogel with thermoresponsive properties synthesised in this study can provide a new method for the application in the fields of drug delivery and separation engineering.

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Spatial differences in water microorganisms in middle and lower reaches of the Huaihe River in spring 2019

PENG Fei, ZHOU Yanfeng, WANG Chenhe, ZHANG Xizhao, LUO Yuting, TANG Xuemei, ZHOU Yifan, WANG Dongwei

Journal of Dalian Ocean University 2022, 37 (5): 830-840. DOI: 10.16535/j.cnki.dlhyxb.2021-261

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In order to understand the basic composition of microorganisms in the middle and lower reaches of the Huaihe River (Anhui Province-Jiangsu Province section), the composition and characteristics of microbial community structure were identified and analyzed by high-throughput sequencing technique and associated with the physical and chemical factors of the water body in 9 sections of four habitat types: tributaries, rivers, lakes (Hongze Lake) and estuaries in the middle and lower reaches of the Huaihe River (Anhui-Jiangsu section)in March 5 to 12, 2019 (dry season). The results showed that the microbial composition and richness of habitats were differentiated to a certain extent under different taxa, with gradual increase in the microbial diversity from tributaries to river channels, and the descending order of species richness in the different habitats as estuarine>Hongze Lake>tributaries>river courses. At the phylum level, Actinobacteria, Proteobacteria and Bacteroidetes were shown to be the common dominant groups at all sites. At the genera level, there were the maximal abundance of Flavobacterium , Rhodoferax and Limnohabitans at each site. Two endemic genera of Zymomonas and Methylibium were observed in river group, while HTCC, Arcobacter and Prosthecobacter were found to be unique in the other three habitat groups. The species with high richness at each sampling site mostly point to the water quality index with high nitrogen content, which converges with the results of water quality analysis, reflecting the basic situation of nitrogen pollution in various habitats. The horizontal dominant genera and Canonical correlation analysis (CCA) revealed that COD Mn , total phosphorus (TP), turbidity (TUR), pH, transparency (SD) and

were the main environmental factors affecting the composition of microorganisms in each site, combined with the correlation analysis and CCA between environmental factors and Alpha diversity. It was found that the middle and lower reaches of water can be divided into four different habitat types according to the difference in microbial community composition, suggesting that water microbes can be used as one of the indicators to reflect the water quality of the middle and lower reaches of the Huaihe River.

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Transmissibility characteristics of methomyl in chlorella-water fleas-zebrafish food chain

CHEN Feng, MENG Shunlong, CHEN Jiazhang, QIU Liping, FAN Limin, SONG Chao, ZHENG Yao, LI Dandan, HU Gengdong

Journal of Dalian Ocean University 2022, 37 (5): 784-792. DOI: 10.16535/j.cnki.dlhyxb.2021-202

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To probe into the bioaccumulation and transfer the effect of methomyl in aquatic organisms, green alga Chlorella vulgaris was exposed to 0, 2, 10, and 50 μg/L of methomyl for 4 days, and fed to water fleas Daphnia magna for 9 days which then fed to zebrafish Danio rerio for 9 days at water temperature of (20±1)℃. The results showed that there was bioaccumulation factor (BCF) as high as 17 549.99, and the bioaccumulation amount of 33.28 μg/g in the green alga exposed to the low concentration groups (2 μg/L) methomyl for 72 h. In the high concentration feeding groups (50 μg/L)， the water fleas fed the green alga exposed to methomyl for 4 days had the maximum bioaccumulation amount of 6.02 μg/g， and biomagnification factor (BMF) of 0.177 0 for 9 days without biomagnification effect. The maximal methomyl concentration of 0.72 μg/g was observed in the body of zebrafish exposed to 50 μg/L methomyl directly for 4 days (exposure group). The green alga had a strong ability to accumulate methomyl, significantly higher than the water fleas (0.12 μg/g)( P <0.05). Methomyl was passed to the water fleas through the feeding process， and then passed to the zebrafish by the water fleas through the feeding process. The passed methomyl inhibited life activities such as food intake and metabolism.

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Effects of salinity on survival, respiration, feeding metabolism and energy budget of juvenile freshwater mussel Solenaia oleivira

Lü Guohua, ZHANG Ting, YAO Jingting, DING Tuqiang, XU Dongpo, ZHAN Mingfei, GU Ruobo, XU Pao, MA Xueyan, JIN Wu, DONG Xinxu, WEN Haibo

Journal of Dalian Ocean University 2022, 37 (5): 802-808. DOI: 10.16535/j.cnki.dlhyxb.2021-220

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In order to explore possibility of freshwater mussel Solenaia oleivira culture in coastal NaCl saline alkali land or tidal flat, the survival test was carried in the freshwater mussel juveniles with wet body weight of (2.63 g± 0.47 g) exposed to acute stress of fresh water (0.20) and high salinity of 2.00, 3.31, 3.70, 4.24, 4.92, 5.82, and 7.00 using the equal log interval method and 50% of the 96 h half lethal salinity (LC 50 ) as the tolerant salinity. The oxygen consumption rate, ammonia excretion rate, food intake rate and fecal excretion rate were measured in freshwater mussel exposed to these salinities by the indoor hydrostatic method, and then the energy budget equation was established at water temperature of (22±1)℃. The results showed that the dead mussel was observed at salinity of 2.00 at 72 h, and at salinity of 7.00 within 48 h, with LC 50 of 4.47 at 96 h. There were significantly higher oxygen consumption rate, ammonia excretion rate, food intake rate, water filtration rate and fecal excretion rate ( P <0.05), with the decreased slightly lower absorption efficiency ( P >0.05), in the juveniles at stress of high salinity (2.23) than those in the freshwater mussel in the fresh water group ( P <0.05). Under high salinity (2.23) stress, the freshwater mussel had significantly higher energy used for respiratory metabolism and feeding metabolism, with increase in the proportion of respiratory energy ( R ), excretory energy ( U ) and fecal energy ( F ) in feeding energy ( C ), and significant decrease in the proportion of growth energy ( P ) in feeding energy. The energy budget equation was described as 100 C =57 . 22 R +9 . 49 U +9 . 05 F +24 . 23 P under fresh water and 100 C =62 . 55 R +13 . 99 U +12 . 05 F +11 . 41 P at high salinity (2.23) stress. The finding indicates that the juvenile firewater mussel S.oleivira has a poor tolerance to sodium salt which shows a significant impact on the respiratory metabolism and food metabolism of the mussel. The coastal NaCl type water is within saline alkali land or tidal flat water where the juvenile freshwater mussel culture should be at a salinity of less than 2.23.

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Genetic diversity and genetic structure of four brooder populations and one captive population of black bream Megalobrama terminalisin the middle and lower reaches of Qiantang River by microsatellite marker

ZHANG Minying, FANG Di’an, ZHOU Yanfeng, REN Long, ZHENG Yuchen, XU Dongpo

Journal of Dalian Ocean University 2022, 37 (5): 775-783. DOI: 10.16535/j.cnki.dlhyxb.2022-007

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In order to master the genetic diversity and genetic structure of different populations of black bream Megalobrama terminalis ，the genes were amplified and genotyped in 768 samples in four broodstock populations including Jingshan (JS) and Mingxing (MX) populations in Huzhou, and Guali Baisong (GLZ) and Xiaoxiang (XX) populations in Hangzhou and one captive population of black bream in the middle and lower reaches of the Qiantang River using microsatellite molecular markers combined with capillary electrophoresis genotyping based on 8 pairs of fluorescent-labeled SSR primers. The results showed that the average number of alleles ( N a ) was 10±1 to 39±7 per locus for each population, with average number of effective alleles ( N e ) from 6.60±0.98 to 14.22±3.08, and the average Shannon’s index ( I ) value from 2.02±0.14 to 2.85±0.21 for the 5 populations. The minimal average values of N a , N e and I were observed in the MX population, higher in the captive population than those in the other populations. The average value of observed heterozygosity ( H o ) was 0.96±0.02 to 0.98±0.01, higher than those of expected heterozygosity ( H e ) in most loci for the 5 populations. AMOVA analysis revealed that there was 5.53% of genetic variation among the populations and 94.47% of genetic variation within populations. The genetic differentiation among 4 broodstock populations was shown to be mild (0< F ST <0.05), to be the genetic differentiation between the captive population and some broodstock populations (such as JS and XX) to be medium (0.05< F ST <0.15). Both structure analysis and PCoA analysis got the consistent results, indicating that all individuals were divided into two genetic clusters. One cluster consisted of most individuals from the captive population, the other cluster consisted of almost all individuals from 4 broodstock populations and a few individuals from the captive population. The findings revealed that there was a higher level of genetic diversity in populations in the middle and lower reaches of the Qiantang River, and heterozygote excess and loss of some alleles occurred wide spreadly in broodstock populations.

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Distribution and relationship with influential factors of dominant zooplankton species in the Northwest Pacific Ocean in spring and winter

FU Feiyu, HAN Peiwu, FANG Zhou, LIU Bilin

Journal of Dalian Ocean University 2022, 37 (3): 489-496. DOI: 10.16535/j.cnki.dlhyxb.2021-130

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In order to explore horizontal distribution characteristics of dominant zooplankton species in the Northwest Pacific Ocean,the dominant zooplankton was surveyed in zooplankton samples collected at 58 stations in the Northwest Pacific Ocean (146°-156°E,28°-35°N) in spring (March) 2019 and winter (December)2020.The relationship between dominant species and influencing factors of zooplankton were evaluated by Pearson correlation analysis and redundancy analysis.The results showed that 602 species (including unknown species) were identified during the two voyages,with more number of species in spring (456) than that in winter (386).Eleven dominant species were observed,including Pleuromamma gracilis , Nannocalanus minor , Neocalanus gracilis and Sagitta hexsaptera in the two seasons.Pearson correlation analysis revealed that latitude had a great influence on spring when there was significant or very significant negative correlation between latitude and Doliolum nationalis ( P <0.05 or P <0.01). Mesocalanus tenuicornis and Eudoxoides spiralis were negatively correlated with latitude ( P <0.05),and Calanus jashnovi was positively correlated with latitude ( P <0.05). Lucicutia flavicornis and S.hexsaptera were positively correlated with salinity in the winter survey area.Redundancy analysis (RDA) was consistent results with Pearson correlation analysis,with the latitude as main factor affecting the abundance of dominant species in spring ( P <0.01),and salinity in winter ( P <0.05).The results showed that the horizontal distribution of dominant species in winter and spring in the Northwest Pacific Ocean was controlled by different factors,which was the result of the comprehensive influence of many factors.The finding indicated that distribution of dominant species in spring was deeply affected by latitude,while salinity was the key factor in winter.

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Regulatory mechanism of neuroendocrine system on immune response in molluscs:a review

WANG Lingling

Journal of Dalian Ocean University 2022, 37 (3): 363-375. DOI: 10.16535/j.cnki.dlhyxb.2022-140

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The neuroendocrine system plays an important regulatory role in the metabolism,growth,development,reproduction and immunity response of animals.The reciprocal regulatory relationship between the neuroendocrine system and the immune system has been increasingly concerned in the fields of neurology,endocrinology,physiology,immunology and even medicine in recent years.Recently,the structure and function of the neuroendocrine system and its immunomodulatory mechanisms in invertebrates have attracted attention.Molluscs are eucoelomatous animals with abundant diversity,strong adaptability and wide distribution.It is found that molluscs have not yet differentiated into nerve and endocrine organs,but have evolved molecular mechanism similar to the neuroendocrine immune system in vertebrates,which can be a vital model to study the origin and evolution of invertebrate neuroendocrine system.This paper describes the molecular composition and activation mechanism of the molluscan neuroendocrine system and its regulatory effect on the immune response,proposes that the structure,function,regulation mechanism and evolutionary significance of molluscan neuroendocrine system remains significantly concern in the future research,aiming to provide reference for further understanding the evolution of neuroendocrine system and NEI-mediated environmental adaptation mechanism in molluscs.

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Isolation,identification and virulence gene of atypical Aeromonas salmonicida from cultured turbot Scophthalmus maximus

WANG He, WANG Wenhao, HUANG Hua, LIU Xiaodan, ZHANG Liwen, YANG Tao, HU Lebin, LI Zhanjun

Journal of Dalian Ocean University 2022, 37 (4): 558-567. DOI: 10.16535/j.cnki.dlhyxb.2021-254

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In order to study the characteristics of atypical Aeromonas salmonicida , a dominant strain BHAS-1 was isolated and purified from the spleen of diseasing turbot individuals using conventional methods. The isolated strain BHAS-1 was identified by morphological observation, physiological and biochemical tests, and PCR specific amplification. The virulence gene and antibiotic sensitivity were also detected. The results showed that BHAS-1 strain was gram-negative cocci with β-hemolytic and no motility. The isolated stain BHAS-1 had similar physiological and biochemical properties to the atypical A.salmonicida , but the strain did not produce indole and cannot utilize mannose. After 16S rRNA, gyrB and vapA sequence alignment analysis, BHAS-1 was identified as A.salmonicida subsp. masoucida , and the virulence genotype was aer + - zot + - dna + - ser + - lip + - sp + - alt + - act + - ast + - epa + - fla + - ahyB + , with LD 50 of 1.62×10 8 CFU/mL. The strain BHAS-1 was sensitive to 13 kinds of antibiotics such as enrofloxacin and tetracycline, resistant to 7 kinds of antibiotics such as puromyn and chloramphenicol, and moderately sensitive to ampicillin and streptomycin, with average resistance rate of 31.82%. In this study, we first reported the infection of A.salmonicida subsp. masoucida to cultured turbot in China. The molecular characteristics and drug sensitivity of the strain BHAS-1 were studied to provide reference for the prevention of furunculosis caused by atypical A.salmonicida . The findings indicate that the application of vap gene can effectively identify different subspecies of A.salmonicida .

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Development and application of monoclonal antibody against IgM of silver prussian carp Carassius auratus gibelio

GUO Baoqin, WEI Chang, WANG Yinan, LI Qiang

Journal of Dalian Ocean University 2022, 37 (3): 450-456. DOI: 10.16535/j.cnki.dlhyxb.2021-136

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In this study,immunoglobulin IgM from the serum of silver prussian carp Carassius auratus gibelio was isolated and purified by ammonium sulfate salting out method combined with protein A affinity chromatography.SDS-PAGE analysis showed that the purified IgM mainly contained two protein bands with relative molecular mass of 82 000 and 25 000,respectively.Balb/c mice were immunized with purified IgM,and five anti-crucian carp IgM monoclonal antibodies,named as 8G1,7C6,8C2,8C5 and 5C2,were obtained by hybridoma technique.Isotype analyzing indicated that 8G1,8C2,8C5 and 5C2 belonged to IgG1 isotype,and 7C6 belonged to IgG2b isotype.Western blot results showed that the five monodonal antibody (MAb) strains specifically recognized IgM light chain molecule with relative molecular mass of 25 000.The indirect immunofluorescence showed that all the five monoclonal antibodies recognized the sIgM cell of silver prussian carp.In addition,the indirect ELISA method for detection of the anti-CyHV-2 serum antibody in sliver carp was established using the anti-IgM monoclonal antibody as primary antibody and AP-labeled sheep anti-mouse Ig as the secondary antibody.The results of condition optimization indicated that the candidate 8C5 is the optimal anti-IgM monoclonal antibody,and 1∶20 dilution of fish serum is the optimal concentration for ELISA detection.Results of this study provides an effective tool for future research on immune response of silver prussian carp and an effective method for the evaluation of immune effect of vaccination.

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Transcriptomics analysis of response of scalloped spiny lobster Panulirus homarus to nitrite stress

LIANG Feishuang, LIANG Huafang, ZHUO Hongbiao, SUN Rongze, WANG Panmei, WEN Chongqing

Journal of Dalian Ocean University 2022, 37 (5): 809-816. DOI: 10.16535/j.cnki.dlhyxb.2021-262

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In order to investigate the mechanism of the response of scalloped spiny lobster Panulirus homarus to nitrite stress, the transcriptomics were comparatively analyzed in hepatopancreas of scalloped spiny lobster with body weight of (39.00±5.31)g exposed to under normal conditions

<0.01 mg/L, control group)and to 80 mg/L nitrite stress prepared by NaNO 2 for 7 d by a transcriptomic sequencing approach. The results showed that 264 differentially related genes were screened, with up-regulated 86 and down-regulated 178. GO functional annotation results showed that the annotated differential genes were primarily involved in functions including binding, catalysis and metabolism, and KEGG pathway enrichment analysis showed that the differentially expressed genes were significantly enriched in focal adhesion, leukocyte transendothelial migration, insulin resistance, tight junctions, and starch and sucrose metabolism pathways. Nine differential genes were randomly selected for qRT-PCR validation, and the fluorescence quantification results were found to be in general agreement with the sequencing results. The findings will provide substantial reference for the research of gene functions in energy metabolism, growth and immunity in scalloped spiny lobster under nitrite stress.

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Artificial propagation,embryonic and early larval development of Schizothorax eurystomus

XIA Zihui, ZHAO He, QIU Meng, NIE Zhulan, CHEN Kexun, LI Xuetao, QIN Xiaofang, WEI Jie

Journal of Dalian Ocean University 2022, 37 (3): 471-481. DOI: 10.16535/j.cnki.dlhyxb.2021-132

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Broodstock Schizothorax eurystomus collected from Kizil River Basin in Xinjiang Uygur Autonomous Region was induced to spawn by hormone injection of pituitary gland (PG),human chorionic gonadotropin (HCG) and luteinizing hormone-releasing hormone analogs (LHRH-A 2 )at various doses and artificial hatchery methods at water temperature from 10 ℃ to 20 ℃ in a 1 ℃ interval in 2019 to accomplish farming and stock enhancement of S.eurystomus .The results showed that success rate and hatching rate were significantly varied with the doses of hormones and water temperature,with the optimal hormone combinations of PG at 10.27 mg/kg,HCG at 300.00 IU/kg and LHRH-A 2 of 19.41 μg/kg.In April and May 2019,the fertilized eggs of S.eurystomus were obtained by artificial propagation,and the development of embryo and larva was observed under artificial incubation conditions,with the optimum incubation water temperature of 16.0-17.0 ℃. S.eurystomus had egg diameters of (2.50±0.24)mm,and reached (3.43±0.11)mm after water swelling;under the condition of water temperature (16.19±0.08)℃,the fertilized eggs were hatched in 145 h and 48 min,with the total accumulated temperature of 2 364.80 ℃·h.The embryonic development process experienced seven stages:embryo disc,cleavage,blastula,gastrula,neuroembryo,organogenesis and hatching.The newly hatched larvae had total length of (8.03±0.15) mm and the yolk sac total length of (20.17±0.96)mm,with the completely exhausted yolk sac at (17.88±0.44)℃ for 480 h.The findings further enrich the early life history data of S.eurystomus and then provide essential data including water temperature regulation,and choice of hormone and dose for resources protection,and large scale artificial propagation of S.eurystomus.

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Isolation and identification of pathogenic bacteria associated with black-mouth disease in sea urchin Strongylocentrotus intermedius

LIU Yansong, ZHANG Weijie, WANG Zhong, YIN Weijun, OU Fanjiang, TIAN Wenzhuo, LIU Lei, CHANG Yaqing

Journal of Dalian Ocean University 2022, 37 (5): 793-801. DOI: 10.16535/j.cnki.dlhyxb.2022-125

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In order to probe into the pathogen of black mouth disease in sea urchin Strongylocentrotus intermedius , a dominant strain (D1) was isolated from the coelomic fluid of the sea urchin with the black mouth disease and then was artificially challenged to the healthy sea urchin to confirm the pathogenicity. The pathogenic bacteria were subjected to electron microscopic observation, gram staining, physiological and biochemical identification and 16S rRNA sequence comparison to identify its classification. The sensitivity of the strain to 30 antibiotics was also detected. The results showed that after being alleloped by D1 strain, the symptoms of the sea urchin with bulbus intermedius are the same as those of the sea urchin with black mouth disease in the natural state and the same strain was isolated in the humor of the sea urchin cavity. It was found that the bacterium was (2.10±0.31)μm × (0.68±0.08)μm (length × width) in size, with gram negative. 16S rRNA comparison showed that the bacterium was similar to Vibrio echinoideorum with as high as 99.04% of similarity. The bacterium reacted positively with sucrose, 6% sodium chloride solution, and oxidase. The physiological and biochemical test and the molecular biology identification results of 16S rRNA revealed that the pathogen was V.echinoideorum . The susceptibility test showed that the strain was sensitive to 16 antibacterial drugs such as ofloxacin, polymyxin B, compound trimoxazole, ampicillin, carboxicillin, and cefazolin and resistant to 11 antibacterial drugs including medithromycin and gentamicin. The finding indicated that V.echinoideorum was the pathogen of the black-mouth disease in sea urchin, which is not sensitive to some antibacterial drugs and has certain drug resistance.

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Research progress in the application of deep learning methods for marine fishery production: a review

ZHANG Shengmao, SUN Yongwen, FAN Wei, TANG Fenghua, CUI Xuesen, WU Yumei

Journal of Dalian Ocean University 2022, 37 (4): 683-695. DOI: 10.16535/j.cnki.dlhyxb.2022-099

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With the continuous decline of global fishery resources, fishery agencies and regional fisheries management organizations of various countries use the fishery observer method to promote sustainable fishing, but the human observer method is characterized by so high cost and low coverage as to difficult to meet the management needs. In recent years, detection speed and accuracy have been continuously enhanced due to continuous emergence and improvement of new deep learning algorithms, thus providing conditions for marine fishery fishing production monitoring. The process of building a fishery production monitoring model is introduced from the aspects of data acquisition, data preprocessing, algorithm design, model training, and model accuracy evaluation. The application of deep learning technology in marine fishery fishing is discussed, and methods such as transfer learning or reinforcement learning are proposed in terms of fishing boats and boat behavior, catches, fishery forecasts, crew members, and fishing gear to expand the identification of target species and enhance detection algorithm，and use high-accuracy feature extraction network to improve the accuracy of target classification, to solve the real-time analysis of electronic monitoring data through edge computing technology and to formulate standards and specifications for electronic monitoring fishery management applications and other key research directions in the future, which provides reference for the promotion of deep learning in marine fishery fishing production.

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Effects of flavor protease on quality of marinated mandarin fish at ice temperature

XU Ming, WAN Jinqing, HOU Boyu, WANG Youjun, SUN Xiaolin, TONG Nian

Journal of Dalian Ocean University 2022, 37 (3): 513-523. DOI: 10.16535/j.cnki.dlhyxb.2021-173

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In order to explore the effect of flavor protease on physical and chemical properties,taste and smell of the marinated mandarin fish Siniperca chuatsi under ice temperature (-2 ℃) conditions,changes in composition,sensory,amino acid nitrogen,trichloroacetic acid (TCA)-soluble peptides,free amino acids,flavor nucleotides,and volatile substances were determined in salted(3% of NaCl) mandarin fish steaks supplemented with flavor protease at a dose of 25,50 and 100 U/g and disposed in a sealed box at ice temperature (-2 ℃) for 10 d.The results showed that addition of flavor protease at ice temperature led to significant effect on the taste and flavor of pickled mandarin fish ( P <0.05),the higher the dose,the greater the effect,with the too high concentration of flavor protease resulting in flesh hardness and loss of taste.It was found that the optimal concentration of flavor protease was of 50 U/g,and under the optimal concentration the best fish quality index,and TCA-soluble peptide of 347.22 mg/100 g,1.5 times as those in the control group,were observed in the 50 U/g group.The maximal umami amino acid content of 60.78 mg/100 g was found on the 6th day,and the maximal inosine nucleotide (IMP) content of 133.83 mg/100 g on the 6th day,1.3 times as that in the control group,and the maximal MSG equivalent content of 7.06 g MSG/100 g on the 6th day,2.8 times as that in the control group.At the same time,there were more abundant volatile substances in the fish meat in the 50 U/g group,with total amount of 2 625.11 μg/100 g,2.7 times as those in the control group.The findings indicated that addition of flavor protease led to significantly improve the quality and flavor of the marinated mandarin fish under the best conditions of 50 U/g enzyme for 6 days,which provided better technology and new ideas for traditional pickled mandarin fish and theoretical reference for the ice temperature research of fishery products.

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Sequence and SNP analysis of Kelch-like gene from pearl oyster Pinctada fucata martensii

YANG Chuangye, ZHANG Chengshu, HUANG Jing, HAO Ruijuan, SHI Shangli, HUANG Ronglian, ZHOU Rui, QIU Jinyu, YAN Yilong, DENG Yuewen

Journal of Dalian Ocean University 2022, 37 (3): 386-393. DOI: 10.16535/j.cnki.dlhyxb.2021-146

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In order to explore the function of Kelch - like gene in pearl oyster Pinctada fucata martensii ,the full-length sequence and SNPs of Kelch - like were analyzed in the present study.It was found that the full-length sequence of Kelch - like was 2 127 bp containing a 5′UTR of 58 bp and a 3′UTR of 44 bp.The open reading frame had length of 2 025 bp encoding 674 amino acids.The Kelch-like sequence contained a BTB domain,a BACK domain and two Kelch domains.The pearl oyster Kelch-like had high homology with Kelch-like of other species in amino acid sequence.Multi-sequence alignment indicated that the BTB and BACK domains were highly conservative,and Kelch domain held a conservative GG site. Kelch - like gene showed significantly higher expression in the marginal zone of mantle ( P <0.05),especially high expression (up-regulated) level in the 6,12 h and 120 h in the repair process of the pearl oyster with damaged mantles ( P <0.05).SNPs analysis of Kelch - like exon region revealed that 31 SNP sites in 56 SNP obtained were moderately polymorphic and the rest were low-level polymorphisms.Among the 56 SNPs,10 SNP loci formed a haplotype set containing,4 haplotypes,of which the haplotype AATCTGTCGG was an excellent haplotype,with significantly greater shell weight than the haplotype AGCCTACCGA and haplotype AGCCTACTTA ( P <0.05).These findings showed that Kelch - like may participated in the shell prismatic layer and haplotype AATCTGTCGG hold the potential as the molecular maker of shell weight in the breeding process,which are of great significance to the breeding of pearl oyster with excellent economic traits.

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Research progress on evaluation of sustainable utilization of fishery resources based on a bibliometric method:a review

LU Quan, WANG Chao, FANG Zhou, ZHANG Baihao, LI Nan, CHEN Xinjun

Journal of Dalian Ocean University 2022, 37 (5): 873-883. DOI: 10.16535/j.cnki.dlhyxb.2021-125

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The sustainable use of fishery resources is a key issue in the sustainable development of fisheries, so in order to ensure the maximum sustainable use of fishery resources, it is necessary to evaluate the development potential of fishery resources. The research on evaluation of the sustainable use of fishery resources is systematically organized and analyzed by using the Core Collection of Web of Science and the CNKI database to retrieve 229 and 238 documents, respectively, internationally and domestically, using the documentary econometric analysis method based on citespace software, and combined with keyword network knowledge map and mutation detection, the sustainable use of fishery resources evaluation of research hot spots and future trends are explored. The overall fluctuation of the research volume of sustainable use of fishery resources showed an upward trend, with more research in this field in the United States, China and Canada. At present, the research hot spots include the evaluation methods and strategies of sustainable use of fishery resources, the impact of climate change on fishery resources, the evaluation of sustainable use of fishery resources based on ecosystem management, and the management system of sustainable use of fishery resources. The key research directions are put forward in the future including the problems in the study of sustainable utilization of fishery resources, such as the improvement and unification of evaluation methods and the supervision and perfection of management systems.

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Functional divergence of different ep300/crebbp gene family members in rainbow trout Oncorhynchus mykiss

WANG Xianzong, LIU Qing, LI Shu

Journal of Dalian Ocean University 2022, 37 (3): 376-385. DOI: 10.16535/j.cnki.dlhyxb.2021-169

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To probe into copy number variation,functional divergence and correlation with hypoxia response of ep 300 /crebbp gene family in rainbow trout Oncorhynchus mykiss ,TBLASTN and BLASTP search and reconstruction of phylogenetic tree were firstly conducted,based on which the members and their orthologs in zebrafish Danio rerio were determined.Tissue expression profiles and co-expressed genes of these copies were analyzed based on original transcriptome sequencing data,and GO enrichment analyses of these co-expressed genes were also conducted.The degree of variation among proteins encoded by these copies was compared by CDD search,multiple sequence alignment and three-dimensional structural modeling.The results showed that there were eight ep 300 /crebbp members in rainbow trout ( ep 300 aa - ep 300 bb , crebbpaa - crebbpbb ),which were all formed by whole genome duplication events and could be divided into four ohnolog pairs corresponding to the four members in D.rerio .There were significant differences in tissue expression profiles,and primary and tertiary structures of encoded proteins between different ohnolog pairs,much smaller differences between two copies within an ohnolog pair.These eight members had different numbers of unique co-expressed genes,and the number of GO terms enriched by these gene collections related to binding,modification,stress/stimulus-response and hypoxia tolerance were also varied greatly. ep 300 ba and ep 300 bb belong to an ohnolog pair,and yet their encoded proteins were varied in 35 positions in conserved domains,with the far greater number than other ohnolog pairs.Furthermore,only co-expressed genes of ep 300 bb enriched GO terms related to stress/stimulus-response and hypoxia tolerance.The findings suggest that ep 300 bb can serve as an important candidate gene for genetic improvement of rainbow trout due to its great evolution rate and stronger correlation with hypoxia tolerance than other ep 300 /crebbp members.

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Prediction of sea surface temperature based on ConvGRU deep learning network model

ZHANG Xuewei, HAN Zhen

Journal of Dalian Ocean University 2022, 37 (3): 531-. DOI: 10.16535/j.cnki.dlhyxb.2021-137

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In order to solve the problems of insufficient combination of temporality and spatiality of traditional time series network models and insufficient ability of batch processing large data of marine environmental elements,sea surface temperature (SST) prediction and analysis were carried out using the SST grid data from 1999 to 2019 in part of the Northwest Pacific Ocean (OISST Products) by ConvGRU deep learning neural network model,that is,combination of the extended algorithm of recurrent neural network (RNN) and convolutional neural network (CNN),and by sample generator to process data,which can effectively deal with the batch problem of time series remote sensing data.The results showed that the ConvGRU model training set had root mean square error of 0.044 9 ℃ and accuracy of 99.69%,and that the validation set had root mean square error of 0.045 2 ℃ and accuracy of 99.64%.Finally,the model established in this paper was used to predict the sea surface temperature data in 2020,with the root mean square error of 0.047 8 ℃ and accuracy of 99.60% in the test set.The average mean absolute deviation of SST prediction was shown to be about 0.379 3 ℃,and the average prediction accuracy to be 97.31%.The findings indicate that the ConvGRU neural network model can predict the trend of sea surface temperature well,which provides a feasible method for SST neural network prediction model.

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Effects of alginate on biofilm formation of Pseudoalteromonas marina and larval settlement and metamorphosis of the mussel Mytilus coruscus

CHEN Huie, HE Kang, HE Chuhan, ZHU Youting, YANG Jinlong, LIANG Xiao

Journal of Dalian Ocean University 2022, 37 (4): 620-626. DOI: 10.16535/j.cnki.dlhyxb.2021-260

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In order to research effects of alginate on biofilm formation of bacterium Pseudoalteromonas marina and the roles of co-formed biofilm on larval settlement and metamorphosis of larval mussel Mytilus coruscus , the settlement and metamorphosis of the mussel larvae were investigated on biofilm of P.marina as a control, and the bacterial biofilm containing alginate solution at final concentration of 0.1, 0.5, 1.0, 1.5 and 2.0 mg/L. In addition, the optimal concentration of alginate was selected to compare and analyze the changes in density, thickness and extracellular products of the biofilm. The bacterial density on the biofilms was shown to be increased with the increase in the alginate concentration. There were significantly increase in thickness and extracellular polysaccharide contents of the biofilm at alginate concentration of 0.5 mg/L ( P <0.05), and finally increase in biofilm-inducing activities. The findings have positive significance for understanding of the induction mechanism of marine shellfish larval settlement and metamorphosis, and provide theoretical basis for the use of biofilms to improve the success rate of mussel seedlings. The appropriate concentration of alginate is 0.5 mg/L.

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Differences in intestinal microbial community between Dolly varden trout Salvelinus malma and lenok Brachymystax lenok with different ages

LIU Peng, LI Lingxue, ZHENG Wei, DU Xiaoyan, YAN Chunmei, LIU Huiji, GAO Chunshan

Journal of Dalian Ocean University 2022, 37 (4): 568-573. DOI: 10.16535/j.cnki.dlhyxb.2021-193

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In order to explore the intestinal microorganisms of Dolly varden trout Salvelinus malma (1 + and 2 + years old) and lenok Brachymystax lenok (4 + years old), MiSeq 16S rRNA high-throughput sequencing was used to sequence and analyze the microbes in intestinal contents of healthy Dolly varden trout and lenok in same aquaculture environment. The results showed that there were 3 896 OTUs in the intestinal contents of the Dolly varden trout, and 1 675 OTUs in the intestinal contents of lenok,showing that the dominant microflora was rich in the contents of Dolly varden trout and lenok. There was higher diversity in the 1 + year old Dolly varden trout groups (H1) than that in the 2 + years old groups (H2), indicating that the intestinal microorganisms were planted in the host intestines with the growth, with the dominant flora Mycoplasma in the Dolly varden trout, and the dominant flora Bacillus in the lenok. PCA analysis revealed that there was the similar intestinal microbial community structure in 1 + and 2 + years old Dolly varden trout groups, and different from the 4 + years old lenok (X4). The findings indicated that the fish of same species with different ages had similar intestinal microbial composition under the same culture environment, and the quite different microbial composition was observed in the two salmon species in the same family and different genera, though with the similar microbial diversity.

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