家蚕突变新小卵(sm-n)的特异性状及其遗传

家蚕卵形突变sm-n(new small egg)为家蚕小卵突变的新类型,与前人研究报道的几种家蚕小卵突变sm、sm-2、sm-3、emi等明显不同,其主要特征为：同一母蛾产卵分离出正常型卵和小卵两种,其中小卵大小不一,为不受精卵,而正常型卵孵化与生长均正常。解剖母蛾观察卵巢管,大小卵粒在每根卵巢管里随机排列,个体间出现小卵的比例有较大差异(分布在20%～90%之间),但总体上小卵比正常卵多,且在越往卵巢管的后端小卵的比例越大,小卵的排列不规则；交配产卵后,初步统计发现小卵百分率越大,则遗腹卵有越多的倾向。同时在解剖过程中发现此小卵系统和无卵突变系统(sm~n)的母蛾卵巢管有增多现象,每个卵巢发生4～6条,每蛾共8～12条卵巢管。用正常系统C108与新小卵杂交,进行遗传分析,结果：新小卵为隐性遗传基因支配,遵循伪母性遗传模式。

The Specific Character and Heredity of Mutant New Small Egg(sm-n)in the Silkworm

The egg shape mutant sm-n(new small egg)is a new type of the small egg mutation in the silk- worm,Bombyx mori.It has significant difference between sm-n and other reported egg mutation of silkworm (including sm,sm-2,sm-3,emi and so on).The key feature of sm-n is:a female moth has both normal type eggs and small eggs,among which the small eggs are unfertilized and their sizes are inequality,while the hatching and growth are normal in the normal type eggs.Observering the ovarioles by dissecting female moths,the normal eggs and small eggs are random arrangement in every ovariole.The percentage of small eggs between individuals is fairly different(20%～90% ),but the number of small eggs are more than that of the normal eggs as a whole.Moreover,the more towards posterior extremity of the ovarioles,the percentage of small eggs is higher,and the arrangement of small eggs is irregular.After mating and oviposition,statistics showed that the higher of the percentage of small eggs is,the more of the unlaid eggs is.Meanwhile,there is increasing phenomenon in the ovariole number of silkworm in the small egg system and another none egg mu- tant system(sm~n).Per ovary has 4～6,and per moth has 8～12 ovariole.Crossing between the normal sys- tem C108 and sm-n,genetic analysis revealed that sm-n is dominated by recessive gene,which follows the pseudo-maternal inherited mode