title: Identification of morc (microrchidia), a mutation that results in arrest of spermatogenesis at an early meiotic stage in the mouse.
abstract: The microrchidia, or morc, autosomal recessive mutation results in the arrest of spermatogenesis early in prophase I of meiosis. The morc mutation arose spontaneously during the development of a mouse strain transgenic for a tyrosinase cDNA construct. Morc -/- males are infertile and have grossly reduced testicular mass, whereas -/- females are normal, indicating that the Morc gene acts specifically during male gametogenesis. Immunofluorescence to synaptonemal complex antigens demonstrated that -/- male germ cells enter meiosis but fail to progress beyond zygotene or leptotene stage. An apoptosis assay revealed massive numbers of cells undergoing apoptosis in testes of -/- mice. No other abnormal phenotype was observed in mutant animals, with the exception of eye pigmentation caused by transgene expression in the retina. Spermatogenesis is normal in +/- males, despite significant transgene expression in germ cells. Genomic analysis of -/- animals indicates the presence of a deletion adjacent to the transgene. Identification of the gene inactivated by the transgene insertion may define a novel biochemical pathway involved in mammalian germ cell development and meiosis.
authors.affiliation: Department of Pathology, The University of Texas Southwestern Medical School, 6000 Harry Hines Boulevard, Dallas, TX 75235, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Watson
authors.forename: A R
authors.initials: AR
authors.lastname: Zinn
authors.forename: N
authors.initials: N
authors.lastname: Inoue
authors.forename: K D
authors.initials: KD
authors.lastname: Hess
authors.forename: J
authors.initials: J
authors.lastname: Cobb
authors.forename: M A
authors.initials: MA
authors.lastname: Handel
authors.forename: R
authors.initials: R
authors.lastname: Halaban
authors.forename: C C
authors.initials: CC
authors.lastname: Duchene
authors.forename: G M
authors.initials: GM
authors.lastname: Albright
authors.forename: R W
authors.initials: RW
authors.lastname: Moreadith
mesh_terms: D000818:Animals; D017209:Apoptosis; D001483:Base Sequence; D017931:DNA Primers; D005127:Eye Color / Q000235:genetics; D017353:Gene Deletion; D005808:Genes, Recessive; D007248:Infertility, Male / Q000235:genetics* / Q000473:pathology; D008297:Male; D008540:Meiosis; D051379:Mice; D008815:Mice, Inbred Strains; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012319:RNA Polymerase II / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D012160:Retina / Q000502:physiology; D013091:Spermatogenesis / Q000235:genetics*; D013094:Spermatozoa / Q000166:cytology / Q000502:physiology*; D013737:Testis / Q000002:abnormalities* / Q000473:pathology
chemical_list: D017931:DNA Primers; D012319:RNA Polymerase II