Sex-chromosome pairing in the ZZWW tetraploid female silkworm during meiosis divison

摘要

The ZZWW tetraploid silkworm can be induced effectively by using low or high temperatures, how-water and centrifugal force. The segregation of characters of their progeny such as sex-ratio is complicated, dueing to the behavior of sex-chromosomes in the ZZWW tetraploid in meiosis. It is important for expecting the generation of polyploid progeny and studying the sex control to understand the pairing and segregation way of sex-chromosome in the ZZWW female silkworm in meiosis. Former scholars have studied it by many means and designs, but it is still a question at issue and no final conclusion has been drawed. By examining the number of sex-hetrerochromatin body (SB) and finding the mixoploid, it is indicated that in the ZZWW female in meiosis random pairing as well as preferential pairing of sex-chromosome is presence and both pairing ways can co-exist, which provides basis for examining the polyploid silkworms and expecting and utilizing the phenotye of their progeny.