Mutations affecting early distribution of primordial germ cells in Medaka (Oryzias latipes) embryo.
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.
Sasado
Takao
T
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.
Morinaga
Chikako
C
Niwa
Katsutoshi
K
Shinomiya
Ai
A
Yasuoka
Akihito
A
Suwa
Hiroshi
H
Hirose
Yukihiro
Y
Yoda
Hiroki
H
Henrich
Thorsten
T
Deguchi
Tomonori
T
Iwanami
Norimasa
N
Watanabe
Tomomi
T
Kunimatsu
Sanae
S
Osakada
Masakazu
M
Okamoto
Yasuko
Y
Kota
Yasuko
Y
Yamanaka
Toshiyuki
T
Tanaka
Minoru
M
Kondoh
Hisato
H
Furutani-Seiki
Makoto
M
D000818:Animals; D005260:Female; D005854:Germ Cells / Q000378:metabolism*; D008297:Male; D009154:Mutation; D009990:Oryzias / Q000196:embryology* / Q000235:genetics*