title: Comparative analysis of zygospore transcripts during early germination in Chlamydomonas reinhardtii.
abstract: The unicellular green alga Chlamydomonas reinhardtii has a haplontic life cycle, and forms diploid zygotes for reproduction. The zygospore, a sporulating zygote, begins germination in response to light signals, generating haploid progenies and inducing several cell-biological events; e.g., DNA synthesis and meiotic division, successively. Their regulatory mechanisms remain largely unknown, so we focused on the early stages of germination and analyzed the dynamics of gene expression associated with the germination process. The gene expression levels of zygospores at 1 and 6h after light exposure were analyzed by a next-generation sequencing platform, the 454 GS Junior. At 6h, the photosynthesis pathway, including its antenna proteins and two methionine metabolism-related genes (methionine synthase and sulfite reductase), were up-regulated compared to 1h after light exposure. Meanwhile, three uncharacterized genes that contained an antibiotic biosynthesis monooxygenase domain and an HSP20/alpha crystallin family protein were specifically expressed at 1h after light exposure. These gene expressions were also verified by quantitative real-time PCR analysis. These results suggest that the photosynthesis and methionine synthesis pathways, both of which occur in the chloroplast, are activated in zygospores at around 6h after light exposure, and that some polyketides and/or a small heat shock protein may be related to the initiation of zygospore germination.
authors.affiliation: Center of Molecular Biosciences, Tropical Biosphere Research Center, University of the Ryukyus, Nishihara, Okinawa 903-0213; Laboratory of Cell and Functional Biology, Faculty of Science, University of the Ryukyus, Nishihara, Okinawa 903-0213. Electronic address: paternal_inheritance@yahoo.co.jp.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Aoyama
authors.affiliation: Center of Molecular Biosciences, Tropical Biosphere Research Center, University of the Ryukyus, Nishihara, Okinawa 903-0213.
authors.forename: Seikoh
authors.initials: S
authors.lastname: Saitoh
authors.affiliation: Initiative Research Unit, College of Science, Rikkyo University, Nishi-Ikebukuro, Tokyo, 171-8501.
authors.forename: Tsuneyoshi
authors.initials: T
authors.lastname: Kuroiwa
authors.affiliation: Laboratory of Cell and Functional Biology, Faculty of Science, University of the Ryukyus, Nishihara, Okinawa 903-0213.
authors.forename: Soichi
authors.initials: S
authors.lastname: Nakamura
mesh_terms: D001483:Base Sequence; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000502:physiology*; D017931:DNA Primers; D017343:Genes, Plant; D018525:Germination; D012333:RNA, Messenger / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D059467:Transcriptome
chemical_list: D017931:DNA Primers; D012333:RNA, Messenger
keywords: Chlamydomonas reinhardtii; Germination; Methionine synthase; Monooxygenase; Photosynthesis pathway