杂交三倍体泥鳅×二倍体泥鳅杂交后代胚胎染色体组构成的研究

Formation of embryonic genomes in hybrid triploid loach×diploid loach

为探讨杂交三倍体泥鳅Misgurnus anguillicaudatus配子染色体组的构成,以杂交三倍体泥鳅(3n)与二倍体泥鳅(2n)为研究对象,配制2n♀×3n♂和3n♀×2n♂杂交组合,对杂交后代的胚胎染色体进行银染(Ag-NORs)、CMA_3/DA/DAPI三重荧光染色和染色体荧光原位杂交(Fluorescence in situ hybridization,FISH)等方面的研究。结果表明:两个杂交组合的杂交后代胚胎染色体有丝分裂中期分裂相中最高银染点数均为3个,位于中部着丝粒染色体(M1)的端部区域;在2n♀×3n♂和3n♀×2n♂杂交后代胚胎染色体有丝分裂中CMA3阳性部位有3个,位于中部着丝粒染色体(M1)的端部区域;将核糖体5.8S+28S r DNA定位在杂交后代胚胎染色体上,两种杂交组合均可检测到3簇杂交信号,位于中部着丝粒染色体(M1)的端部区域。研究表明,杂交三倍体泥鳅无论雌雄与二倍体泥鳅杂交所产生的后代染色体组构成均为3套染色体组,进而可推测,杂交三倍体泥鳅无论雌雄均可产生(1.5~2)n的配子,该结果为三倍体泥鳅配子染色体组成提供了细胞遗传学证据。

The embryo chromosomes were investigated in hybrid triploid loach Misgurnus anguillicaudatus×diploid loach prepared cross combinations of 2n♀×3n♂and 3n♀×2n♂by silver straining,chromomycin A 3(CMA 3),and fluorescence in situ hybridization(FISH)to explore the formation of gamete genomes for hybrid triploid loach(2n×4n).Results showed that the both hybrid offsprings had the maximum silver staining point of 3 at the end of the metacentric chromosome(M1)during the mitotic metaphase.There were CMA 3 positive in the highest mitotic metaphase 3 regions of 2n♀×3n♂and 3n♀×2n♂hybrids,and 5.8S+28S rDNA was located at the embryo chromosome of hybrid offspring.Three hybridization signals were found at the end of metacentric chromosome(M1)in the two cross combinations,indicating that 3 genomes were formed by hybridization between the hybrid triploid loach,whether male or female,and it is speculated that the hybrid triploid loach,for either male or female,will produce(1.5-2)n gamete.The findings provide cytogenetic evidence for the chromosome composition of triploid loach gamete genomes.