title: Sexually dimorphic expression of a laryngeal-specific, androgen-regulated myosin heavy chain gene during Xenopus laevis development.
abstract: Masculinization of the larynx in Xenopus laevis frogs is essential for the performance of male courtship song. During postmetamorphic (PM) development, the initially female-like phenotype of laryngeal muscle (slow and fast twitch fibers) is converted to the masculine form (entirely fast twitch) under the influence of androgenic steroids. To explore the molecular basis of androgen-directed masculinization, we have isolated cDNA clones encoding portions of a new Xenopus myosin heavy chain (MHC) gene. We have detected expression of this gene only in laryngeal muscle and specifically in males. All adult male laryngeal muscle fibers express the laryngeal myosin (LM). Adult female laryngeal muscle expresses LM only in some fibers. Expression of LM during PM development was examined using Northern blots and in situ hybridization. Males express higher levels of LM than females throughout PM development and attain adult levels by PM3. In females, LM expression peaks transiently at PM2. Treatment of juvenile female frogs with the androgen dihydrotestosterone masculinizes LM expression. Thus, LM appears to be a male-specific, testosterone-regulated MHC isoform in Xenopus laevis. The LM gene will permit analysis of androgen-directed sexual differentiation in this highly sexually dimorphic tissue.
authors.affiliation: Department of Biological Sciences, Sherman Fairchild Center for the Life Sciences, Columbia University, New York, New York 10027.
authors.forename: D S
authors.initials: DS
authors.lastname: Catz
authors.forename: L M
authors.initials: LM
authors.lastname: Fischer
authors.forename: M C
authors.initials: MC
authors.lastname: Moschella
authors.forename: M L
authors.initials: ML
authors.lastname: Tobias
authors.forename: D B
authors.initials: DB
authors.lastname: Kelley
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004247:DNA; D013196:Dihydrotestosterone / Q000031:analogs & derivatives* / Q000494:pharmacology; D005260:Female; D005786:Gene Expression Regulation; D005796:Genes / Q000187:drug effects*; D007830:Larynx / Q000196:embryology*; D008297:Male; D008969:Molecular Sequence Data; D009132:Muscles / Q000196:embryology*; D009218:Myosins / Q000235:genetics*; D016415:Sequence Alignment; D012727:Sex Characteristics; D012733:Sex Differentiation; D014982:Xenopus laevis / Q000196:embryology
chemical_list: D013196:Dihydrotestosterone; C030445:dihydrotestosterone propionate; D004247:DNA; D009218:Myosins