鲫鲤杂交品系异源染色体的减数分裂特征研究

The F1 hybrid fish of red crucian carp (Carassius auratus red var.) (♀; 2n = 100)×common carp (Cyprinus carpio L.) (♂; 2n = 100) could break through the reproductive barriers, which made them can produce bisexual hybrid offspring and strains. Analyzing the characteristics of heterogenetic chromosome meiosis in hybrids could give a view about why the hybrids can produce stable hybrids, which is of great significance in biological evolution research and fish genetic breeding. The study would first commit to screen chromosomal loci factors in different chromosomal region, including centromere loci (263bp repetitive sequence), chromosome arm loci (5S rDNA and BAC clones), terminal loci (Telomeres repetitive sequence), chromosomal chiasmata loci（MLH1）and synaptonemal complexes loci（SYCP1 and SYCP3). Using above marked factors, the chromosomal localization performed by FISH or IF, would be carried out to observe the characteristics of pairing, synapsis, recombination and separation in meiosis of hybrid fish. Then, some key factories of meiosis such as spo-11 and mlh1 would be analyzed to study the molecular genetic relationships between hybrids and original parents, which could explore whether the meiosis genes have selective pressure in the hybrid strains and would set base for the following study of meiotic gene function in hybrid fish.

鲫鲤杂交能突破F1生殖难关产生可育的杂交品系。解析该杂交鱼突破生殖难关过程中异源染色体的减数分裂特征，可进一步探究杂交品系稳定传代的内在机制，在生物进化研究和育种实践方面都具有重要意义。本研究一方面选定染色体标记因子，包括着丝粒标记因子（263bp着丝粒定位重复序列）；染色体臂间标记因子（5SrDNA；异源四倍体鲫鲤BAC克隆）；染色体末端标记因子（Telomeres）、染色体交叉标记因子（MLH1）及联会复合体标记因子（SYCP1、SYCP3）等，对鲫鲤杂交鱼生殖细胞减数分裂配对、联会、重组（交叉）、分离过程进行系统的FISH和免疫荧光检测，以期待解析杂交鱼异源染色体减数分裂的遗传定位特征；另一方面，选用减数分裂关键基因spo-11, mlh1等在杂交鱼与异源双亲间进行分子遗传特征比较，探究源自异源双亲的减数分裂因子在杂交品系传代中是否存在选择压力，为进一步的基因功能分析奠定基础。

鲫鲤杂交能突破F1生殖难关产生可育的杂交品系。解析该杂交鱼突破生殖难关过程中异源染色体的减数分裂特征，可进一步探究杂交品系稳定传代的内在机制，在生物进化研究和育种实践方面具有重要意义。本研究一方面选定染色体标记因子，包括着丝粒标记因子（263bp着丝粒定位重复序列）；染色体臂间标记因子（5SrDNA；染色体末端标记因子（Telomeres）、RNA Pol II CTD (S5)、染色体交叉标记因子（MLH1）及联会复合体标记因子（SYCP3）等，对鲫鲤杂交鱼生殖细胞减数分裂配对、联会、重组（交叉）、分离过程进行系统的FISH和免疫荧光检测，及系统的细胞学显微和超微结构检测，发现鲫鲤杂交鱼生殖细胞在突破减数分裂障碍过程中，会经历一个初级精母细胞减数分裂前期染色体端粒和核膜接触异常到正常的转变过程；发现了减数第一次分裂、第二次分裂不完全从而导致的染色体加倍配子的可能机制；也证明了染色体数加倍后的同源染色体配对发生在复制形成的相同染色体之间从而揭示了鲫鲤杂交品系染色体异源稳定性机制；另一方面，选用减数分裂关键基因spo-11, mlh1等在杂交鱼与异源双亲间进行分子遗传特征比较，结果证明了鲫鲤杂交鱼形成过程中，减数分裂关键基因保持杂合遗传且表达正常，为解析远缘杂交跨越生殖障碍奠定重要的遗传学基础。