Chromosomal composition of androgenetic diploidy induced by cold shocking of wild tetraploid loach Misgurnus anguillicaudatus
CHEN Qi1, SUN Yuqing1, ZHENG Xinyi1, SHAN Gu1, LI Yajuan1, CAO Xiaojuan2, ZHU Xinping3, ZHOU He1*
1.College of Fisheries and Life Science, Dalian Ocean University, Dalian 116023, China; 2. College of Fisheries, Key Laboratory of Freshwater Animal Breeding, Ministry of Agriculture and Rural Affairs; Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction, Ministry of Education; Hubei Province Engineering Laboratory of Pond Agriculture,Huazhong Agricultural University, Wuhan 430070, China; 3.Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences,Guangzhou 510380, China
Abstract: In order to explore a new way of fish androgenesis and the composition of gamete genome produced by wild tetraploid loach Misgurnusanguillicaudatus,the fertilized eggs of hybrid loach [wild tetraploid loach (4n=100)♂×diploid loach (2n=50)♀] were exposed to (20±1)℃ (control group) and to 3 ℃ water for 60 min and then to (20±1)℃ (treatment group). Then the blood red cell nuclear volume, chromosome karyotype, Ag-NORs banding pattern and fluorescence in situ hybridization (FISH) were observed and investigated in the embryos at myomere stage. The results showed that the hybrid triploid loach in the control group had red blood cell nuclear volume of(38.29±3.14)μm3,and that the male diploid in treatment group had red blood cell nuclear volume of (27.92±3.58)μm3, with the ratio of 1.37∶1 in red blood cell nuclear volume between the hybrid triploid loach and the male diploid loach. Karyotype analysis revealed that the triploid loach embryos had chromosome number of 3n=75, with karyotype formula of 15m+6sm+54t, and NF=96 in the control group; the diploid loach embryos with androgenetic development had chromosome number of 2n=50, and the karyotype formula of 10m+4sm+36t, with NF=64. Fish and Ag-NORs indicated that three fish hybridization signals were detected at the end of the short arm of three chromosomes in the triploid loach embryos in the control group; that two fish hybridization signals were detected at the ends of the short arms of two chromosomes in the embryo chromosomes in diploid loach. There were 1-3 Ag-NORs in chromosomes and interphase nuclei of triploid loach in the control group and 1-2 Ag-NORs in diploid loach embryos in treatment group. It was found that the karyotypes of diploid loach were composed of two sets of genomes, indicating that wild tetraploid male loach produced diploid (2n) gametes, which provides important genetic evidence that tetraploid male loach is a genetic tetraploid with four sets of genomes.
2021, Vol. 36 
