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Positional cloning of the sex‐linked giant egg ( Ge ) locus in the silkworm, Bombyx mori
Author(s) -
Fujii T.,
Abe H.,
Kawamoto M.,
Banno Y.,
Shimada T.
Publication year - 2015
Publication title -
insect molecular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.955
H-Index - 93
eISSN - 1365-2583
pISSN - 0962-1075
DOI - 10.1111/imb.12150
Subject(s) - biology , genetics , locus (genetics) , mutant , bombyx mori , intron , gene , positional cloning , bombyx , exon , chromosomal translocation , microbiology and biotechnology
The giant egg ( G e ) locus is a Z ‐linked mutation that leads to the production of large eggs. Cytological observations suggest that an unusual translocation of a large fragment of the W chromosome bearing a putative egg size‐determining gene, E sd , gave rise to giant egg mutants. However, there is currently no molecular evidence confirming either a W–Z translocation or the presence of E sd on the W chromosome. To elucidate the origin of giant egg mutants, we performed positional cloning. We observed that the B ombyx mori. orthologue of the human Phytanoyl‐CoA dioxygenase domain containing 1 gene (PHYHD1) is disrupted in giant egg mutants. PHYHD1 is highly conserved in eukaryotes and is predicted to be a F e( II ) and 2‐oxoglutarate‐dependent oxygenase. Exon skipping in one of the two available G e mutants is probably caused by the insertion of a non‐long terminal repeat transposon into intron 4 in the vicinity of the 5′ splice site. Segmental duplication in Ge 2 , an independent allele, was caused by unequal recombination between short interspersed elements inserted into introns 3 and 5. Our results indicate that (1) B ombyx PHYHD1 is responsible for the G e mutants and that (2) the G e locus is unrelated to the W ‐linked putative E sd . To our knowledge, this is the first report describing the phenotypic defects caused by mutations in PHYHD1 orthologues.