title: From Somatic Cells to Oocytes: A Novel Yolk Protein Produced by Ovarian Somatic Cells in a Stony Coral, Euphyllia ancora.
abstract: To gain a better understanding of how corals form their eggs at both the molecular and cellular levels, we performed a differential screen (suppression subtractive hybridization) to identify genes related to oocyte development in a stony coral, Euphyllia ancora. Through the course of screening, a novel gene that contains three alternate repeats of fibronectin domain 2 and epidermal growth factor (EGF)-like domains, as well as an additional calcium-binding EGF-like domain (EGF-CA), was identified and tentatively named euphy after the scientific name of the coral, E. ancora. Quantitative RT-PCR revealed that expression levels of euphy increased in female colonies as the coral approached reproductive season. Tissue distribution analysis followed by mRNA in situ hybridization revealed that euphy is highly expressed in the ovarian (mesenterial) somatic cells in the body of E. ancora. Staining of tissue sections with an antibody against euphy protein (Euphy) revealed Euphy immunoreactivity in both ovarian somatic cells and oocytes. Subsequent Western blotting demonstrated the presence of abundant Euphy in unfertilized mature eggs. These results indicate that Euphy produced in the ovarian somatic cells is transported to and accumulates within oocytes as a yolk protein during oogenesis. We previously showed that two major yolk proteins, vitellogenin and egg protein, are similarly produced by ovarian somatic cells. Hence, the present study uncovered the third ovarian somatic-derived yolk protein in corals. Our data provide new information that contributes to a more comprehensive understanding of coral egg formation.
authors.affiliation: Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung, Taiwan Institute of Marine Environment and Ecology, National Taiwan Ocean University, Keelung, Taiwan shikina@mail.ntou.edu.tw.
authors.forename: Shinya
authors.initials: S
authors.lastname: Shikina
authors.affiliation: Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan.
authors.forename: Yi-Ling
authors.initials: YL
authors.lastname: Chiu
authors.affiliation: Tungkang Biotechnology Research Center, Fisheries Research Institute, Tungkang, Taiwan.
authors.forename: Yan-Horn
authors.initials: YH
authors.lastname: Lee
authors.affiliation: Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung, Taiwan Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan b0044@mail.ntou.edu.tw.
authors.forename: Ching-Fong
authors.initials: CF
authors.lastname: Chang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D037421:Anthozoa / Q000378:metabolism*; D001483:Base Sequence; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D004527:Egg Proteins / Q000235:genetics* / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000378:metabolism; D005260:Female; D005353:Fibronectins / Q000378:metabolism; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism*; D010053:Ovary / Q000166:cytology* / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D012098:Reproduction; D014018:Tissue Distribution
chemical_list: D002135:Calcium-Binding Proteins; D018076:DNA, Complementary; D004527:Egg Proteins; D005353:Fibronectins; D012333:RNA, Messenger; D004815:Epidermal Growth Factor
keywords: Euphyllia ancora; coral; novel gene; oocyte; oogenesis; yolk protein