title: Sexual reproduction and sex determination in green algae.
abstract: The sexual reproductive processes of some representative freshwater green algae are reviewed. Chlamydomonas reinhardtii is a unicellular volvocine alga having two mating types: mating type plus (mt+) and mating type minus (mt-), which are controlled by a single, complex mating-type locus. Sexual adhesion between the gametes is mediated by sex-specific agglutinin molecules on their flagellar membranes. Cell fusion is initiated by an adhesive interaction between the mt+and mt-mating structures, followed by localized membrane fusion. The loci of sex-limited genes and the conformation of sex-determining regions have been rearranged during the evolution of volvocine algae; however, the essential function of the sex-determining genes of the isogamous unicellular Chlamydomonas reinhardtii is conserved in the multicellular oogamous Volvox carteri. The sexual reproduction of the unicellular charophycean alga, Closterium peracerosum-strigosum-littorale complex, is also focused on here. The sexual reproductive processes of heterothallic strains are controlled by two multifunctional sex pheromones, PR-IP and PR-IP Inducer, which independently promote multiple steps in conjugation at the appropriate times through different induction mechanisms. The molecules involved in sexual reproduction and sex determination have also been characterized.
authors.affiliation: Department of Chemical and Biological Sciences, Faculty of Science, Japan Women's University, 2-8-1 Mejirodai, Bunkyo-ku, Tokyo, 112-8681, Japan. sekimoto@fc.jwu.ac.jp.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sekimoto
mesh_terms: D005075:Biological Evolution; D002448:Cell Adhesion / Q000502:physiology; D002459:Cell Fusion; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000254:growth & development; D000460:Chlorophyta / Q000235:genetics* / Q000254:growth & development / Q000502:physiology*; D058119:Closterium / Q000235:genetics / Q000254:growth & development; D005618:Fresh Water; D008018:Life Cycle Stages / Q000235:genetics / Q000502:physiology; D008561:Membrane Fusion / Q000502:physiology; D012098:Reproduction / Q000235:genetics* / Q000502:physiology*; D019849:Sex Determination Processes / Q000235:genetics* / Q000502:physiology*; D044446:Volvox / Q000235:genetics / Q000254:growth & development
keywords: Chlamydomonas; Closterium; Sex determination; Sexual reproduction