四倍体鲫鲤、三倍体湘云鲫染色体减数分裂观察

摘要

In the present paper, the chromosome pairing during meiosis Ⅰ(MⅠ)of spermatocytes in allotetraploid hybrids of the red crucian carp (Carassius auratus, red var.)(♀)×common carp Cyprinus carpio (♂), allotriploid crucian carp, diploid red crucian carp and common carp was investigated. As the control groups, their chromosome number in metaphase of mitosis was also examined. During MⅠ, the homologous chromosomes of allotetraploid hybrids were paired, showing 100 bivalents, no univalent, trivalent and quadrivalent being found. The chromosome spreads of the allotriploid in MⅠconsisted of 50 bivalents and 50 unsynapsed univalent. Both in diploid red crucian carp and diploid common carp, only 50 bivalents were observed respectively. In the control groups, the metaphase spreads of chromosomes in mitosis in allotetraploid hybrids, allotriploids, diploid red crucian carp and common carp were 4n=200, 3n=150, and 2n=100, respectively. In all the different species, the bivalent number in MⅠ agreed with the chromosome number in mitosis. The 200 chromosomes the allotetraploids possessed only formed 100 bivalents during MⅠ, indicating that they were able to produce stably diploid gametes, maintaining the tetraploidy from one generation to the next one. The coexistence of bivalents and univalent in MⅠin triploid crucian carp resulted in the failure to form the normal mature gametes, providing the evidence on the chromosome level for the sterility of the triploids[Acta Zoologica Sinica 51(1):89-94,2005].%用精巢细胞直接制片法观察了异源四倍体鲫鲤、三倍体湘云鲫和二倍体红鲫、湘江野鲤精母细胞染色体第一次减数分裂中期配对情况;作为对照,观察了上述四种鱼肾细胞的有丝分裂中期染色体.在精母细胞第一次减数分裂中,异源四倍体鲫鲤同源染色体两两配对,形成100个二价体,没有观察到单价体、三价体和四价体;三倍体湘云鲫精母细胞形成50个二价体和50个单价体;红鲫和湘江野鲤精母细胞分别形成50个二价体.肾细胞检测表明异源四倍体的染色体数目为4n=200;湘云鲫为3n=150;红鲫和湘江野鲤分别为2n=100.减数分裂时染色体分布情况与肾细胞染色体检测结果相吻合.具有四套染色体的异源四倍体鲫鲤在减数分裂中只形成100个二价体,而不形成25个四价体或其它形式,为产生稳定一致的二倍体配子提供了重要的遗传保障,也为人工培育的异源四倍体鲫鲤群体能够世世代代自身繁衍下去提供了重要的遗传学证据.三倍体湘云鲫在减数分裂过程中出现二价体、单价体共存,同源染色体在配对和分离中出现紊乱,导致非整倍体生殖细胞的产生,为湘云鲫的不育性提供了染色体水平上的证据[动物学报 51(1):89-94,2005].