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Mutation of a vitelline membrane protein, BmEP80, is responsible for the silkworm “Ming” lethal egg mutant

Author:
Chen, Anli, Gao, Peng, Zhao, Qiaoling, Tang, Shunming, Shen, Xingjia, Zhang, Guozheng, Qiu, Zhiyong, Xia, Dingguo, Huang, Yongping, Xu, Yunmin, He, Ningjia
Source:
Gene 2013 v.515 pp. 313-319
ISSN:
0378-1119
Subject:
Bombyx mori, DNA, RNA, RNA interference, chromosomes, eclosion, eggs, genes, homozygosity, membrane proteins, molecular cloning, moths, mutants, mutation, phenotype, polymerase chain reaction, pupae, silkworms, two-dimensional gel electrophoresis, vitelline membrane
Abstract:
The egg stage is an important stage in the silkworm (Bombyx mori) life cycle. Normal silkworm eggs are usually short, elliptical, and laterally flattened, with a sometimes hollowed surface on the lateral side. However, the eggs laid by homozygous recessive “Ming” lethal egg mutants (l-em) lose water and become concaved around 1h, ultimately exhibiting a triangular shape on the egg surfaces. We performed positional cloning, and narrowed down the region containing the gene responsible for the l-em mutant to 360kb on chromosome 10 using 2287 F2 individuals. Using expression analysis and RNA interference, the best l-em candidate gene was shown to be BmEP80. The results of the inverse polymerase chain reaction showed that an ~1.9kb region from the 3′ untranslated region of BmVMP23 to the forepart of BmEP80 was replaced by a >100kb DNA fragment in the l-em mutant. Several eggs laid by the normal moths injected with BmEP80 small interfering RNAs were evidently depressed and exhibited a triangular shape on the surface. The phenotype exhibited was consistent with the eggs laid by the l-em mutant. Moreover, two-dimensional gel electrophoresis showed that the BmEP80 protein was expressed in the ovary from the 9th day of the pupa stage to eclosion in the wild-type silkworm, but was absent in the l-em mutant. These results indicate that BmEP80 is responsible for the l-em mutation.
Agid:
990296