TRANSCRIPTION FACTOR Bmsage PLAYS A CRUCIAL ROLE IN SILK GLAND GENERATION IN SILKWORM, Bombyx mori.
Salivary gland secretion is altered in Drosophila embryos with loss of function of the sage gene. Saliva has a reduced volume and an increased electron density according to transmission electron microscopy, resulting in regions of tube dilation and constriction with intermittent tube closure. However, the precise functions of Bmsage in silkworm (Bombyx mori) are unknown, although its sequence had been deposited in SilkDB. From this, Bmsage is inferred to be a transcription factor that regulates the synthesis of silk fibroin and interacts with another silk gland-specific transcription factor, namely, silk gland factor-1. In this study, we introduced a germline mutation of Bmsage using the Cas9/sgRNA system, a genome-editing technology, resulting in deletion of Bmsage from the genome of B. mori. Of the 15 tested samples, seven displayed alterations at the target site. The mutagenesis efficiency was about 46.7% and there were no obvious off-target effects. In the screened homozygous mutants, silk glands developed poorly and the middle and posterior silk glands (MSG and PSG) were absent, which was significantly different from the wild type. The offspring of G0 mosaic silkworms had indel mutations causing 2- or 9-bp deletions at the target site, but exhibited the same abnormal silk gland structure. Mutant larvae containing different open-reading frames of Bmsage had the same silk gland phenotype. This illustrated that the mutant phenotype was due to Bmsage knockout. We conclude that Bmsage participates in embryonic development of the silk gland.
Institute of Sericulture and Apiculture, College of Animal Sciences, Zhejiang University, Hangzhou, People's Republic of China.
Hu-hu
HH
Xin
Institute of Sericulture and Apiculture, College of Animal Sciences, Zhejiang University, Hangzhou, People's Republic of China.
Deng-pan
DP
Zhang
Institute of Sericulture and Apiculture, College of Animal Sciences, Zhejiang University, Hangzhou, People's Republic of China.
Rui-ting
RT
Chen
Institute of Sericulture and Apiculture, College of Animal Sciences, Zhejiang University, Hangzhou, People's Republic of China.
Zi-zheng
ZZ
Cai
Institute of Sericulture and Apiculture, College of Animal Sciences, Zhejiang University, Hangzhou, People's Republic of China.
Yan
Y
Lu
Institute of Sericulture and Apiculture, College of Animal Sciences, Zhejiang University, Hangzhou, People's Republic of China.
Shuang
S
Liang
Institute of Sericulture and Apiculture, College of Animal Sciences, Zhejiang University, Hangzhou, People's Republic of China.
Yun-gen
YG
Miao
D000818:Animals; D012831:Bombyx / Q000196:embryology / Q000235:genetics / Q000502:physiology*; D064112:Clustered Regularly Interspaced Short Palindromic Repeats; D004625:Embryo, Nonmammalian; D005088:Exocrine Glands / Q000196:embryology* / Q000502:physiology; D005260:Female; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism*; D007814:Larva / Q000235:genetics / Q000254:growth & development; D009154:Mutation; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D019476:Insect Proteins; D014157:Transcription Factors
Bmsage; development; silk gland; silkworm; transcription factor