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Distribution and function of germ plasm in cytoplasmic fragments from centrifuged eggs of the goldfish, C arassius auratus
Author(s) -
Kitauchi T.,
Saito T.,
Motomura T.,
Arai K.,
Yamaha E.
Publication year - 2012
Publication title -
journal of applied ichthyology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.392
H-Index - 62
eISSN - 1439-0426
pISSN - 0175-8659
DOI - 10.1111/jai.12068
Subject(s) - biology , germ plasm , polarity in embryogenesis , embryo , allantois , cytoplasm , blastula , microbiology and biotechnology , cleavage (geology) , blastomere , yolk sac , gonadal ridge , yolk , human fertilization , embryogenesis , anatomy , embryoid body , embryonic stem cell , genetics , gene , gastrulation , fishery , paleontology , adult stem cell , fracture (geology)
Summary In teleosts, primordial germ cells ( PGC )s are formed by the inheritance of cytoplasmic determinants called ‘germ plasm’ during early embryonic development. Although several molecular components of the germ plasm have been identified, it is still unclear if cytoplasmic regions that show expression of germ cell specific marker genes such as vasa and nanos 1 are necessary and sufficient for inducing PGC s in the embryo. In this study, the relationship between PGC formation and yolk granules was examined by reducing numbers of granules in the embryo shortly after fertilization. Ten minutes after fertilization, goldfish eggs were centrifuged at 700 g . This treatment resulted in the formation of a transparent blastodisc with apparently no yolk granules. When this segment was removed from the centrifuged egg and placed in culture, it exhibited a holoblastic mode of cleavage and developed into a spherical embryoid body. Maternal vasa mRNA was detected at the connections between blastomeres that developed from the separated fragment. Electron dense structures could be detected along the cleavage furrow in a position seemingly identical to vasa mRNA localization. When the spherical embryoid body from the centrifuged eggs was transplanted onto the blastodisc of a normal blastula stage embryo, PGC s from the donor embryo were detected around the genital ridge in the resulting chimeric larva at 10 days post‐fertilization. These results suggest that cytoplasmic fragments from centrifuged eggs contain factors sufficient for PGC differentiation. However, transplantation of the putative cytoplasmic germ plasm into host blastodiscs did not result in the formation of PGC s.