Retrotransposon "Qian" mediated segmental duplication in silkworm, Bombyx mori.
Transposable elements constitute a large fraction of the eukaryotic genomes. They have the potential to alter genome structure and play a major role in genome evolution. Here, we report a segmental duplication mediated by a novel long terminal repeat (LTR) retrotransposon as the cause of an egg-shell recessive lethal mutant (l-em mutant) in silkworm (Bombyx mori). The segmental duplication resulted in the duplication of six genes and the disruption of two genes. Disruption of BmEP80 (B. mori egg protein 80), a gene encoding a major egg-shell structure protein, is likely responsible for the lethal water-loss phenotype in the l-em/l-em mutant. Our data revealed that BmEP80 is present in the inner egg-shell layer and plays important roles in resistance to water efflux form eggs. A novel LTR retrotransposon (named as "Qian") was identified and the model for the Qian-mediated chromosomal segmental duplication was proposed. Detail biochemical and genomic analyses on the l-em mutant offer an opportunity to demonstrate that an LTR retrotransposon could trigger duplication of a chromosomal segment (∼96.3 kb) and confer novel phenotype.
State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing 400715, China. Electronic address: xym2636@swu.edu.cn.
Yunmin
Y
Xu
Department of Horticulture, Michigan State University, MI 48824, USA. Electronic address: jiangn@msu.edu.
Ning
N
Jiang
State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing 400715, China. Electronic address: zacharyzou@yahoo.cn.
Ziliang
Z
Zou
Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA. Electronic address: jaketu@vt.edu.
Zhijian
Z
Tu
Jiangsu University of Science and Technology, Zhenjiang, Jiangsu 212003, China. Electronic address: chenanli1982@yahoo.com.cn.
Anli
A
Chen
Jiangsu University of Science and Technology, Zhenjiang, Jiangsu 212003, China. Electronic address: qlzhao302@126.com.
Qiaoling
Q
Zhao
State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing 400715, China. Electronic address: xbxzh@swu.edu.cn.
Zhonghuai
Z
Xiang
State Key Laboratory of Silkworm Genome Biology, Southwest University, Beibei, Chongqing 400715, China. Electronic address: hejia@swu.edu.cn.
Ningjia
N
He
D000818:Animals; D001483:Base Sequence; D012831:Bombyx / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D004528:Egg Shell / Q000378:metabolism; D007814:Larva / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D018626:Retroelements; D056916:Segmental Duplications, Genomic; D020079:Terminal Repeat Sequences
D018626:Retroelements
Bombyx mori; Egg-shell mutant; Retrotransposon; Segmental duplication