一种新的家蚕突变体——4龄幼虫致死突变的发现

The Discovery of a Novel Bombyx mori Mutant,the Lethal Mutation in the Fourth Instar Larvae

在对家蚕品种P33的饲养过程中发现一种新的幼虫致死型突变体,其幼虫在3龄第2天就表现出体型较正常个体小,生长发育缓慢的特征,3龄期延长约2 d,4龄起蚕后极少取食,生长发育基本停滞,并于4龄第3-4天陆续死亡。将此突变体命名为4龄幼虫致死突变（lethal mutant in the fourth instar larvae,l-4i）。经遗传分析初步判断该突变体由常染色体上的一个隐性遗传基因控制,为纯合致死。该突变体可以作为解析家蚕生长发育机制的重要素材。

A novel lethal mutant was found during rearing of silkworm（ Bombyx mori） strain P33. Compared with normal larvae,the mutant larvae had smaller body size and slower growth rate after day 2 of the 3rd instar. The duration of the3 rd instar was extended by about 2 days. The 4th instar newly exuviated larvae barely ate mulberry leaves,almost stopped growth and development,and died successively on day 3 to day 4 in the 4th instar. Therefore,this mutant was named lethal mutation in the fourth instar larvae（ l-4i）. Genetic analysis preliminarily indicated that the lethal mutation is controlled by a recessive gene located on euchromosome and has homogeneous lethal effect. This mutant can be used as an important material for elucidation of growth and development mechanism in the silkworm.