title: Mutations affecting early distribution of primordial germ cells in Medaka (Oryzias latipes) embryo.
abstract: The development of germ cells has been intensively studied in Medaka (Oryzias latipes). We have undertaken a large-scale screen to identify mutations affecting the development of primordial germ cells (PGCs) in Medaka. Embryos derived from mutagenized founder fish were screened for an abnormal distribution or number of PGCs at embryonic stage 27 by RNA in situ hybridization for the Medaka vasa homologue (olvas). At this stage, PGCs coalesce into two bilateral vasa-expressing foci in the ventrolateral regions of the trunk after their migration and group organization. Nineteen mutations were identified from a screen corresponding to 450 mutagenized haploid genomes. Eleven of the mutations caused altered PGC distribution. Most of these alterations were associated with morphological abnormalities and could be grouped into four phenotypic classes: Class 1, PGCs dispersed into bilateral lines; Class 2, PGCs dispersed in a region more medial than that in Class 1; Class 3, PGCs scattered laterally and over the yolk sac area; and Class 4, PGCs clustered in a single median focus. Eight mutations caused a decrease in the number of PGCs. This decrease was observed in the offspring of heterozygous mothers, indicating the contribution of a maternal factor in determining PGC abundance. Taken together, these mutations should prove useful in identifying molecular mechanisms underlying the early PGC development and migration.
authors.affiliation: Japan Science and Technology Agency, ERATO Kondoh Differentiation Signaling Project, Kondoh Research Group, Kinki-chihou Hatsumei Center Building, Yoshida-Kawaramachi 14, Sakyo-ku, Kyoto 606-8305, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Sasado
authors.forename: Chikako
authors.initials: C
authors.lastname: Morinaga
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Niwa
authors.forename: Ai
authors.initials: A
authors.lastname: Shinomiya
authors.forename: Akihito
authors.initials: A
authors.lastname: Yasuoka
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Suwa
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Hirose
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yoda
authors.forename: Thorsten
authors.initials: T
authors.lastname: Henrich
authors.forename: Tomonori
authors.initials: T
authors.lastname: Deguchi
authors.forename: Norimasa
authors.initials: N
authors.lastname: Iwanami
authors.forename: Tomomi
authors.initials: T
authors.lastname: Watanabe
authors.forename: Sanae
authors.initials: S
authors.lastname: Kunimatsu
authors.forename: Masakazu
authors.initials: M
authors.lastname: Osakada
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Okamoto
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Kota
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Yamanaka
authors.forename: Minoru
authors.initials: M
authors.lastname: Tanaka
authors.forename: Hisato
authors.initials: H
authors.lastname: Kondoh
authors.forename: Makoto
authors.initials: M
authors.lastname: Furutani-Seiki
mesh_terms: D000818:Animals; D005260:Female; D005854:Germ Cells / Q000378:metabolism*; D008297:Male; D009154:Mutation; D009990:Oryzias / Q000196:embryology* / Q000235:genetics*