title: Genetic mapping of Z chromosome and identification of W chromosome-specific markers in the silkworm, Bombyx mori.
abstract: In the silkworm, Bombyx mori, the female is the heterogametic (ZW) sex and the male is homogametic (ZZ). The female heterogamety is a typical situation in the insect order Lepidoptera. Although the W chromosome in silkworm is strongly female determining, no W-linked gene for a morphological character has been found on it. The Z chromosome carries important traits of economic value as well as genes for various phenotypic traits, but only 2% of molecular information based on its relative size is known. Studies conducted so far indicate that the Z-linked genes are not dosage compensated. In the present study, we constructed a genetic map of randomly amplified polymorphic DNA fragments (RAPD), simple sequence repeats (SSR), and fluorescent intersimple sequence repeat PCR (FISSR) markers for the Z chromosome using a backcross mapping population. A total of 16 Z-linked markers were identified, characterized, and mapped using od, a recessive trait for translucent skin as an anchor marker yielding a total recombination map of 334.5 cM. The linkage distances obtained suggested that the markers were distributed throughout the Z chromosome. Four RAPD and four SSR markers that were linked to W chromosome were also identified. The proposed mapping approach should be useful to identify and map sex-linked traits in the silkworm. The economic and evolutionary significance of Z- and W-linked genes in silkworm, in particular, and lepidopterans, in general, is discussed.
authors.affiliation: Laboratory of Molecular Genetics, Centre for DNA Fingerprinting and Diagnostics, ECIL Road, Nacharam, Hyderabad 500076, India.
authors.forename: G M
authors.initials: GM
authors.lastname: Nagaraja
authors.forename: G
authors.initials: G
authors.lastname: Mahesh
authors.forename: V
authors.initials: V
authors.lastname: Satish
authors.forename: M
authors.initials: M
authors.lastname: Madhu
authors.forename: M
authors.initials: M
authors.lastname: Muthulakshmi
authors.forename: J
authors.initials: J
authors.lastname: Nagaraju
mesh_terms: D000818:Animals; D001483:Base Sequence; D012831:Bombyx / Q000235:genetics*; D002874:Chromosome Mapping; D005260:Female; D005819:Genetic Markers; D008297:Male; D018598:Minisatellite Repeats; D008969:Molecular Sequence Data; D020161:Physical Chromosome Mapping / Q000379:methods*; D019105:Random Amplified Polymorphic DNA Technique; D012730:Sex Chromosomes / Q000235:genetics*
chemical_list: D005819:Genetic Markers