自然四倍体泥鳅雄核发育二倍体染色体组构成研究

为探究鱼类雄核发育新途径及自然四倍体泥鳅所产生的配子染色体组构成,采用自然四倍体泥鳅(4n=100)为父本、二倍体泥鳅(2n=50)为母本进行杂交,受精后5 min将受精卵放入3℃水中处理60 min诱导雄核发育二倍体泥鳅,并对其后代的血红细胞核体积、染色体核型、Ag-NORs带型及荧光原位杂交(FISH)信号等进行了研究。结果表明:对照组杂交三倍体泥鳅血红细胞核体积为(38.29±3.14)μm³,处理组雄核发育二倍体泥鳅血红细胞核体积为(27.92±3.58)μm³,二者血红细胞核体积之比为1.37∶1;杂交三倍体泥鳅胚胎染色体数目3n=75,核型公式为15m+6sm+54t,NF=96,雄核发育二倍体泥鳅胚胎染色体数目2n=50,核型公式为10m+4sm+36t,NF=64;杂交三倍体泥鳅胚胎染色体中,在3个染色体短臂的端部检测到3个FISH杂交信号,雄核发育二倍体泥鳅胚胎染色体中,在2个染色体短臂的端部检测到2个FISH杂交信号;杂交三倍体泥鳅染色体和间期核中,呈现出Ag-NORs数目为1~3个,雄核发育二倍体泥鳅胚胎染色体和间期核中,呈现出Ag-NORs数目为1~2个。研究表明,雄核发育二倍体泥鳅的染色体组构成为2套染色体组,表明自然四倍体雄性泥鳅能产生二倍体(2n)配子,该结果为自然四倍体雄性泥鳅是具有4套染色体组的遗传四倍体提供了重要的遗传学证据。

Chromosomal composition of androgenetic diploidy induced by cold shocking of wild tetraploid loach Misgurnus anguillicaudatus

In order to explore a new way of fish androgenesis and the composition of gamete genome produced by wild tetraploid loach Misgurnus anguillicaudatus,the fertilized eggs of hybrid loachwild 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.