RRC ID 55716
Author Fujii T, Yamamoto K, Banno Y.
Title Translucent larval integument and flaccid paralysis caused by genome editing in a gene governing molybdenum cofactor biosynthesis in Bombyx mori.
Journal Insect Biochem Mol Biol
Abstract Translucency of the larval integument in Bombyx mori is caused by a lack of uric acid in the epidermis. Hime'nichi translucent (ohi) is a unique mutation causing intermediate translucency of the larval integument and male-specific flaccid paralysis. To determine the gene associated with the ohi mutation, the ohi locus was mapped to a 400-kb region containing 29 predicted genes. Among the genes in this region, we focused on Bombyx homolog of mammalian Gephyrin (BmGphn), which regulates molybdenum cofactor (MoCo) biosynthesis, because MoCo is indispensable for the activity of xanthine dehydrogenase (XDH), a key enzyme in uric acid biosynthesis. The translucent integument of ohi larvae turned opaque after injection of bovine xanthine oxidase, which is a mammalian equivalent to XDH, indicating that XDH activity is defective in ohi larvae. RT-PCR and sequencing analysis showed that (i) in ohi larvae, expression of the BmGphn gene was repressed in the fat body where uric acid is synthesized, and (ii) there was no amino acid substitution in the ohi mutant allele. Finally, we obtained BmGphn knockout alleles (hereafter denoted as BmGphnΔ) by using CRISPR/Cas9. The resulting ohi/BmGphnΔ larvae had translucent integuments, demonstrating that BmGphn is the gene responsible for the ohi phenotype. Our results show that repressed expression of BmGphn is a causative factor for the defective MoCo biosynthesis and XDH activity observed in ohi larvae. Interestingly, all male BmGphnΔ homozygotes died before pupation and showed a flaccid paralysis phenotype. The genetic and physiological mechanisms underlying this flaccid paralysis phenotype are also discussed.
Volume 99
Pages 11-16
Published 2018-8
DOI 10.1016/j.ibmb.2018.04.008
PII S0965-1748(18)30106-1
PMID 29803701
MeSH Animals Bombyx* / genetics Bombyx* / metabolism Coenzymes* / biosynthesis Coenzymes* / genetics Gene Editing* Insect Proteins* / genetics Insect Proteins* / metabolism Larva Metalloproteins* / biosynthesis Metalloproteins* / genetics Pteridines*
IF 3.618
Times Cited 1
Silkworms p50 p55 w16