Transcription factor lark has been demonstrated to play multiple functions in Drosophila, but the function of this gene in embryonic development remains to be elucidated. In this study, the CRISPR/Cas9 gene-editing method was used to construct a Bmlark mutant strain of Bombyx mori to investigate the roles of this gene. The results showed that the homozygous mutant Bmlark−/− was lethal. The Bmlark−/− embryos showed obvious developmental defects, such as defective sclerotization and melanization of the exoskeleton. A transcriptomic comparison of Bmlark−/− and wild-type embryos showed that the differentially expressed genes were mainly enriched in the structure and metabolic processes of chitin and cuticles. While the expression levels of chitin metabolism-related enzyme genes did not significantly change, in the mutant embryos compared to the wild-type embryos, the expression levels of 63 putative cuticle protein genes showed significant differences. Among which, 35 genes were downregulated and 28 genes were upregulated. The expression levels of the transcription factor BmPOUM2 and eight wing disc cuticle protein genes (WCP) also changed. BmPOUM2, WCP5, WCP9, WCP10, WCP11 were downregulated and WCP1, WCP2, WCP3, WCP6 were upregulated in Bmlark−/− embryos. While the expression level of TH in the tyrosine-mediated pigmentation pathway was upregulated in the mutant embryos, the expression levels of the four key pigment synthesis genes DDC, aaNAT, Laccase2A, and yellow-f2 were significantly downregulated. The expression levels of 63 putative cuticle protein genes, eight WCP genes, and five pigment synthesis genes significantly changed in Bmlark mutant B. mori compared to those of the wildtype. These results suggest that Bmlark is essential for normal development of cuticle and tyrosine-mediated melanization in silkworm embryos.

Yuling Peng

Jin Li

Kangkang Niu

Man Wang

Yanfei Chen

Chunmei Tong

Qili Feng

BMC Genomics

BMC GENOMICS 是一本开放获取、同行评议的期刊，考虑关于基因组规模分析、功能基因组学和蛋白质组学各个方面的文章。BMC GENOMICS 是 BMC 系列的一部分，该系列出版专注于个人研究需求的特定主题期刊生物学和医学所有领域的社区。我们提供高效、公平和友好的同行评审服务，并致力于出版所有可靠的科学，前提是工作提供的知识有所进步。

BMC Genomics is an open access, peer-reviewed journal that considers articles on all aspects of genomic-scale analysis, functional genomics, and proteomics. As part of the BMC series, it focuses on specific topics that cater to the research needs of the biological and medical communities. We provide efficient, fair, and friendly peer review services and are committed to publishing all reliable science, provided that the work contributes to the advancement of knowledge.

BMC Genomics 是一本开放获取、同行评审的期刊，接受关于基因组规模分析、功能基因组学和蛋白质组学各个方面的研究文章。作为 BMC 系列的一部分，该系列专注于满足生物学和医学领域研究者的特定需求。我们提供高效、公平和友好的同行评审服务，致力于出版所有可靠的科学研究，前提是这些研究能够推动知识的进步。

Category	Quartile
生物学	2
生物学, 生物工程与应用微生物	2
生物学, 遗传学	2

Bmlark is essential for embryonic development

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Journal Info

Category	Quartile
GENETICS & HEREDITY	2