title: Molybdenum cofactor deficiency causes translucent integument, male-biased lethality, and flaccid paralysis in the silkworm Bombyx mori.
abstract: Uric acid accumulates in the epidermis of Bombyx mori larvae and renders the larval integument opaque and white. Yamamoto translucent (oya) is a novel spontaneous mutant with a translucent larval integument and unique phenotypic characteristics, such as male-biased lethality and flaccid larval paralysis. Xanthine dehydrogenase (XDH) that requires a molybdenum cofactor (MoCo) for its activity is a key enzyme for uric acid synthesis. It has been observed that injection of a bovine xanthine oxidase, which corresponds functionally to XDH and contains its own MoCo activity, changes the integuments of oya mutants from translucent to opaque and white. This finding suggests that XDH/MoCo activity might be defective in oya mutants. Our linkage analysis identified an association between the oya locus and chromosome 23. Because XDH is not linked to chromosome 23 in B. mori, MoCo appears to be defective in oya mutants. In eukaryotes, MoCo is synthesized by a conserved biosynthesis pathway governed by four loci (MOCS1, MOCS2, MOCS3, and GEPH). Through a candidate gene approach followed by sequence analysis, a 6-bp deletion was detected in an exon of the B. mori molybdenum cofactor synthesis-step 1 gene (BmMOCS1) in the oya strain. Moreover, recombination was not observed between the oya and BmMOCS1 loci. These results indicate that the BmMOCS1 locus is responsible for the oya locus. Finally, we discuss the potential cause of male-biased lethality and flaccid paralysis observed in the oya mutants.
authors.affiliation: Laboratory of Silkworm Genetic Resources, Institute of Genetic Resources, Graduate School of Bio Resources and Bioenvironmental Science, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Tsuguru
authors.initials: T
authors.lastname: Fujii
authors.affiliation: National Institute of Agrobiological Sciences, Tsukuba 305-8634, Japan.
authors.forename: Kimiko
authors.initials: K
authors.lastname: Yamamoto
authors.affiliation: Laboratory of Silkworm Genetic Resources, Institute of Genetic Resources, Graduate School of Bio Resources and Bioenvironmental Science, Kyushu University, Fukuoka 812-8581, Japan. Electronic address: banno@agr.kyushu-u.ac.jp.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Banno
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D012831:Bombyx / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D003001:Cloning, Molecular; D003067:Coenzymes / Q000737:chemistry / Q000172:deficiency / Q000235:genetics*; D049308:Dioxygenases / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D019476:Insect Proteins / Q000737:chemistry / Q000172:deficiency / Q000235:genetics*; D007814:Larva / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D008297:Male; D008667:Metalloproteins / Q000737:chemistry / Q000172:deficiency / Q000235:genetics*; D000090006:Molybdenum Cofactors; D011621:Pteridines / Q000737:chemistry
chemical_list: D003067:Coenzymes; D049308:Dioxygenases; D005656:Fungal Proteins; D019476:Insect Proteins; D008667:Metalloproteins; D000090006:Molybdenum Cofactors; D011621:Pteridines; C022261:molybdopterin; C503093:xanthine dioxygenase, Aspergillus nidulans
keywords: Bombyx mori; Larval coloration; Molybdenum cofactor deficiency; Uric acid; Xanthine dehydrogenase