三倍体虹鳟性转换及性腺发育的研究

用高温刺激法获得三倍体虹鳟幼鱼。从开始投饵起，分别投喂含有不同浓度17β-雌二醇(0～60μg/μg)的饵料，持续60天，获得了93%～100%的高三倍体雌性率(对照组的雌性率为52%)。三倍体雄鱼可观察到其精子形成，但性腺成熟度较相对的二倍体差；三倍体雌鱼的生殖细胞多停留在偶线期到粗线期，未发现有性成熟个体。实验结果推测，三倍体虹鳟雌鱼的不育现象看来不是由于雌雄基因组的组成差异而致，更可能是由于三组染色体造成对虹鳟卵巢发育更大的阻力。雌二醇处理对三倍体虹鳟幼鱼的生长和成活没有明显的影响。

SEX REVERSAL AND GONADAL DEVELOPMENT OF TRIPLOID RAINBOW TROUT (ONCORHYNCHUS MYKISS)

Juvenile triploid Rainbow trout (Oncorhynchus mykiss), obtained by heat shock of fertilized eggs, were orally administered 17 β-estradiol at concentrations of 0～60 μg/g diet, for 60 days following first feeding. The control group was comprised of 52% female and 48% male, whereas the test group (including phentotypical males undergone sex reversal) comprised 93～100% female fish. Gonadal development was determined in the 1～3 years old females and males. In the testis of triploid males, spermatogenesis was observed suggesting male triploids eventually mature, whereas the oocytes of triploid females were retarded at the zygotene to pachytene (chromosome pairing) stages suggesting that the ovaries of triploid females were undeveloped. On the other hand, oocytes of triploid were not developed later than the peri-nucleolus stage and no mature triploid female was observed. These results suggest that the sterility in triploid female sterility may not be caused by genomic differences between male and female. The growth and survival rates two months after hormone treatment were the same in the treated and control groups, suggesting that the hormone treatment did not make a significant difference to early growth and survival. Our results suggest that triploid females, including the sex reversed males, were completely sterile and 17 β-estradiol treatment to induce sex-reversal may be useful for creating all-female sterile fish.