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罗非鱼类(Tilapiini)含3个属70余种,种间和属间颇易人工杂交,但尼罗罗非鱼(Oreochromis niloticus)和萨罗罗非鱼(Sarotherodon melanotheron)人工杂交难度大,产苗概率甚低,要获得数量足够的可用于生产的杂交子代相当困难。该文对这两种鱼及其正交(O.niloticus♀×S.melanotheron♂)和反交(S.melanotheron♀×O.niloticus♂)子代的头肾细胞的核型进行了比较。此外,采用同工酶电泳方法检测肾、肝、眼、肌肉、心中乳酸脱氢酶等4种同工酶的表型差异。4种遗传型罗非鱼具有相同的染色体二倍数(2n=44)和总臂数(NF=50),但各具不同的染色体类型,尼罗罗非鱼为3对近中着丝点染色体(sm)、12对近端着丝点染色体(st)和7对端着丝点染色体(t);萨罗罗非鱼为1对中间着丝点染色体(m)、2对sm、12对st和7对t;正反杂交子代表现为介于双亲之间的混合类型,为0.5对m、2.5对sm、12对st和7对t。在同工酶中,仅见肾脏乳酸脱氢酶电泳结果有清晰差异,尼罗罗非鱼出现5条谱带,萨罗罗非鱼3条,而杂交子代6条,且所有谱带的迁移率和活性均表现出多态性。据此初步认为,核型和同工酶方面的差异可能是导致这两种不同属罗非鱼生殖隔离的遗传原因,这些差异也可能为这两种(属)鱼的分类学提供新的遗传背景资料。
Tilapiini contains more than 70 species belonging to three genera, which are easy to be cross-breed and inter-genus artificial crosses. However, artificial mating of Oreochromis niloticus and Sarotherodon melanotheron is difficult, The probability of seedling production is so low that it is quite difficult to obtain a sufficient number of hybrid progeny that can be used for production. In this paper, karyotypes of head kidney cells of both fish and their offspring (O.niloticus × S. melanotheron♂) and cross (S.melanotheron × O.niloticus♂) were compared. In addition, isozyme electrophoresis was used to detect the phenotypic differences of four isozymes such as kidney, liver, eye, muscle and heart lactate dehydrogenase. The four genotypes of tilapia had the same chromosome doubling number (2n = 44) and total arm number (NF = 50), but each had different chromosome types. Nile tilapia (sm), 12 pairs of proximal centromere (st) and 7 pairs of centromeric chromosomes (t), one pair of middle tonal chromosomes (m), two pairs of sm, 12 pairs st and 7 pairs of t; the positive and negative hybrids represent now a mixed type between parents, 0.5 pair m, 2.5 pair sm, 12 pair st and 7 pair t. Among the isozymes, only the results of renal LDH electrophoresis showed a clear difference. There were 5 bands in Nile tilapia, 3 in Sallow tilapia, and 6 in hybrid generation, and the migration of all bands Rate and activity showed polymorphism. Based on this, it is initially believed that differences in karyotypes and isozymes may be the genetic cause of reproductive segregation in these two different species of tilapia. These differences may also provide new genetic basis for the taxonomy of both species Background information.