人工诱导湘云金鳙雌核发育的研究

Induction of gynogenesis in red bighead carp (Aristichthys nobilis red var.)

湘云金鳙的卵子经适宜UV剂量灭活处理的异源四倍体鲫鲤精子激活后,在4~6℃下冷休克11~13 min,抑制第二极体排出和第一次卵裂使染色体加倍,成功获得了极体雌核发育（mei G）和有丝分裂雌核发育（mit G）湘云金鳙二倍体个体。结果发现,用异源四倍体鲫鲤精子诱导获得meiG、mit G成活率可达到19.4%±2.3%和7.3%±1.9%。运用形态学测量、染色体计数和微卫星标记技术对雌核发育二倍体个体（meiG、mitG）进行了分析,其染色体数目为48;微卫星分析表明,雌核发育二倍体基因组完全来自于母本,没有受到父本染色体的污染,证实其为雌核发育二倍体。对雌核发育湘云金鳙性腺发育进行连续跟踪观察,所有雌核发育个体全为雌性,其中89%的个体的卵巢发育正常,为证明其雌性的性别决定类型为XX提供了证据。此外,雌核发育湘云金鳙F1的体色较普通湘云金鳙的体色偏红。雌核发育湘云金鳙的获得对其体色的稳定、种质资源的遗传改良和性别决定的研究等具有一定意义。

Gynogenesis was induced in red bighead carp（Aristichthys nobilis red var. ）eggs using the UV- irradiated diploid sperm of allotetraploid hybrids, which were derived from crossing of red crucian carp（ ♀ ） x common carp （ ♂ ）, with cold shock treatment in 4 - 6 ℃ water for 11 - 13 min to make chromosome doubled. Different initiation time of treatments resulted in two types of diploid gynogenetic red bighead carp ： meiotic gynogenetic （ meiG ） and mitotic gynogenetic （mitG）. The survival rates of meiG and mitG were 19.4% ± 2. 3%, 7. 3% ± 1. 9% respectively. The gynogenetic fish were confirmed by morphological characteristics,chromosome counting, and microsatellite DNA analysis. The results showed that both meiG and mitG gynogenetic fish were identified as diploid with 48 chromosomes, which produed exclusively bands being same as that in maternal parents and discriminated from that in allotetraploid hybrids by microsatellite DNA analysis. All the gynogenetic fish were female,89% of which showed normal ovary development. It provided important data for suggesting XX genotype in female red bighead carp. In addition, the body color of gynogenesis offspring （ gynogenetic red bighead carp （ ♀ ） x wild red bighead carp （ ♂ ） ） was redder than that in wild red bighead carp. The formation of gynogenetic red bighead carp should be a valuable contribution to body color non-degradation, genetic improvement in fish breeding, as well as sex determination researches in fish.