江西彭泽鲫生殖方式的初步研究

为探究鳡和翘嘴鲌精子在诱导彭泽鲫雌核发育子代中的异精效应，实验分别以鳡和翘嘴鲌精子激活彭泽鲫卵的胚胎发育获得子二代 (F₂)群体：P×G (彭泽鲫♀×鳡♂)和P×Q (彭泽鲫♀×翘嘴鲌♂)，以P×P (彭泽鲫♀×彭泽鲫♂)F₂为对照，比较各群体的染色体核型、DNA含量、形态学特征以及生长等。结果显示，P×G、P×Q和P×P的核型分别为3n=150=45m+66sm+27st+12t、3n=150=54m+51sm+39st+6t和3n=150=51m+48sm+45st+6t，与父本鳡的核型 (2n=48=10m+24sm+12st+2t)和翘嘴鲌的核型 (2n=48=16m+26sm+6st)明显不同；P×G和P×Q的DNA含量与P×P比值在95%的置信区间内 (均为0.97)；上述结果表明，P×G和P×Q的F₂群体均为雌核发育子代。基于形态学参数的主成分分析显示，P×G和P×Q与P×P散点分布区域基本无重叠；P×G和P×Q与P×P间能通过判别函数进行初步判别 (准确率达97.8%)，即存在显著的形态学差异；这表明P×Q和P×G子代存在异精效应。与P×P相比，P×G和P×Q的F₂群体各日龄的平均体重、平均体长、增重率和增长率均表现出优势，且P×G优势显著。综上所述，鳡和翘嘴鲌精子均能诱导彭泽鲫卵的雌核发育，且不同的精子源诱导对雌核发育子代的影响不同，存在典型的“异精效应”。

Preliminary studies on the mode of reproduction in crucian carp (Carassius auratus) of pengze

The technology of allogynogenesis has great application potential in the breeding of superior varieties. Carassius auratus var. pengsenensis is a kind of hermaphroditic triploid crucian carp with natural gynogenetic reproduction and it is one of the best freshwater breeding varieties in China. The development of gynogenesis of C. auratus var. pengsenensis induced with heterologous sperms can produce normal surviving progeny. The study on allogynogenetic biological effects in progeny can provide reference for the cultivation of excellent new varieties of C. auratus var. pengsenensis. In this study, the eggs of C. auratus var. pengsenensis were fertilized with sperms from Elopichthys bambusa and Culter alburnus for two successive generations, respectively. We succeeded in obtaining their second generation offsprings, P×G (C. auratus var. pengsenensis ♀ × E. bambusa ♂) and P×Q (C. auratus var. pengsenensis ♀ × C. alburnus ♂). The chromosomal karyotype, DNA content, morphological traits, and growth performance of offsprings were compared with P×P (C. auratus var. pengsenensis). The findings suggest that the karyotype formulas of P×G, P×Q and P×P was 3n=150=45m+66sm+27st+12t, 3n=150=54m+51sm+39st+6t and 3n=150=51m+48 sm+45st+6t, respectively. It is significantly different from the karyotype of E. bambusa (2n=48=10m+24sm+12st+2t) and of C. alburnus (2n=48=16m+26sm+6st). Furthermore, observed ratio of nuclear DNA content of P×G and P×Q to nuclear DNA content of P×P was within the 95% confidence interval (both 0.97), showing that P×G and P×Q produced by heterologous sperms were gynogenetic triploid fishes. The findings of principal component analysis based on morphological parameters reveal almost no overlap between the scatter plots of P×Q and P×G and P×P; there seem to be significant morphological differences between P×Q and P×G and P×P (P<0.05) that can be made preliminary discrimination by discriminant function (the accuracy rate reached 97.8%). These findings suggest that there is a significant allogynogenetic biological effects between P×Q and P×G progeny. As compared to P×P, P×G and P×Q demonstrated benefits in terms of mean body weight, mean body length, body weight growth rate and body length growth rate at each age, and P×G had significant benefits (P<0.05). In conclusion, sperms from both E. bambusa and C. alburnus can promote gynogenic development of C. auratus var. pengsenensis eggs, and different sperm sources have varied effects on the development of gynogenic nucleus and progeny, as expected from allogynogenetic biological effects. Through the research results, we can preliminarily judge the better sperm stimulation source, which lays the foundation for the subsequent breeding of C. auratus var. pengsenensis excellent new varieties.