title: Ultrabithorax and abdominal-A specify the abdominal appendage in a dosage-dependent manner in silkworm, Bombyx mori.
abstract: In insects, there is a considerable diversity in leg distribution on the body, including number, segmental arrangement, morphological identity and consequent function, but the genetic basis for these differences is not well understood. Here by positional cloning, we showed that a ~355 kb region, including Bombyx mori Ultrabithorax (BmUbx) and abdominal-A (Bmabd-A), was responsible for the silkworm mutant Kh-extra-crescents-like (EKh-l) that displayed additional thoracic limb-like legs on the first abdominal segment (A1) and occasionally on the second abdominal segment (A2). We found that BmUbx gene was downregulated at both messenger RNA level and protein level in EKh-l embryo, while its expression domain in the EKh-l embryo was almost the same as that in the wild type. Whereas Bmabd-A was upregulated at both levels and was ectopically overexpressed on the supernumerary leg-bearing segments in EKh-l. Compared with the previously reported Ecs-l mutant in which increased expression of both BmUbx and Bmabd-A gave rise to ectopic proleg-like appendages on the same segments, we propose that overexpressed Bmabd-A gene is capable to promote the outgrowth of extra leg appendages on A1 and A2 segments, whereas BmUbx gene is required to specify accurate morphologies of the ectopic legs in a dosage-dependent manner in silkworm. These results provide insights into how these hox genes regulate the leg morphologic diversity on the same segments.
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China.|Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, Chongqing, China.
authors.forename: X L
authors.initials: XL
authors.lastname: Tong
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China.|Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, Chongqing, China.
authors.forename: M Y
authors.initials: MY
authors.lastname: Fu
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China.
authors.forename: P
authors.initials: P
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China.
authors.forename: L
authors.initials: L
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China.|Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, Chongqing, China.
authors.forename: Z H
authors.initials: ZH
authors.lastname: Xiang
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China.|Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, Chongqing, China.
authors.forename: C
authors.initials: C
authors.lastname: Lu
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China.|Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agriculture, Southwest University, Chongqing, China.
authors.forename: F Y
authors.initials: FY
authors.lastname: Dai
mesh_terms: D000818:Animals; D012831:Bombyx / Q000196:embryology* / Q000235:genetics; D002874:Chromosome Mapping; D005121:Extremities; D018628:Gene Dosage; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox; D008040:Genetic Linkage; D019476:Insect Proteins / Q000235:genetics*
chemical_list: D019476:Insect Proteins