title: Changes in gene expression and cellular localization of insulin-like growth factors 1 and 2 in the ovaries during ovary development of the yellowtail, Seriola quinqueradiata.
abstract: A method of controlling the somatic growth and reproduction of yellowtail fish (Seriola quinqueradiata) is needed in order to establish methods for the efficient aquaculture production of the species. However, little information about the hormonal interactions between somatic growth and reproduction is available for marine teleosts. There is accumulating evidence that insulin-like growth factor (IGF), a major hormone related somatic growth, plays an important role in fish reproduction. As the first step toward understanding the physiological role of IGF in the development of yellowtail ovaries, we characterized the expression and cellular localization of IGF-1 and IGF-2 in the ovary during development. We histologically classified the maturity of two-year-old females with ovaries at various developmental stages into the perinucleolar (Pn), yolk vesicle (Yv), primary yolk (Py), secondary yolk and tertiary yolk (Ty) stages, according to the most advanced type of oocyte present. The IGF-1 gene expression showed constitutively high levels at the different developmental stages, although IGF-1 mRNA levels tended to increase from the Py to the Ty stage with vitellogenesis, reaching maximum levels during the Ty stage. The IGF-2 mRNA levels increased as ovarian development advanced. Using immunohistochemistry methods, immunoreactive IGF-1 was mainly detected in the theca cells of ovarian follicles during late secondary oocyte growth, and in part of the granulosa cells of Ty stage oocytes. IGF-2 immunoreactivity was observed in all granulosa cells in layer in Ty stage oocytes. These results indicate that follicular IGFs may be involved in yellowtail reproduction via autocrine/paracrine mechanisms.
authors.affiliation: Seikai National Fisheries Research Institute, Fisheries Research Agency, 1551-8 Taira-machi, Nagasaki, Nagasaki 851-2213, Japan; Institute for East China Sea Research, Nagasaki University, 1551-7 Taira-machi, Nagasaki, Nagasaki 851-2213, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Higuchi
authors.affiliation: Seikai National Fisheries Research Institute, Fisheries Research Agency, 1551-8 Taira-machi, Nagasaki, Nagasaki 851-2213, Japan.
authors.forename: Koichiro
authors.initials: K
authors.lastname: Gen
authors.affiliation: Institute for East China Sea Research, Nagasaki University, 1551-7 Taira-machi, Nagasaki, Nagasaki 851-2213, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Izumida
authors.affiliation: National Research Institute of Aquaculture, Fisheries Research Agency, 224-1 Hiruta, Tamaki, Watarai, Mie 516-0193, Japan.
authors.forename: Yukinori
authors.initials: Y
authors.lastname: Kazeto
authors.affiliation: Goto Station, Seikai National Fisheries Research Institute, Fisheries Research Agency, 122-7 Nunoura, Tamanoura, Goto, Nagasaki 853-0508, Japan.
authors.forename: Takuro
authors.initials: T
authors.lastname: Hotta
authors.affiliation: Seikai National Fisheries Research Institute, Fisheries Research Agency, 1551-8 Taira-machi, Nagasaki, Nagasaki 851-2213, Japan.
authors.forename: Toshinori
authors.initials: T
authors.lastname: Takashi
authors.affiliation: Seikai National Fisheries Research Institute, Fisheries Research Agency, 1551-8 Taira-machi, Nagasaki, Nagasaki 851-2213, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Aono
authors.affiliation: Institute for East China Sea Research, Nagasaki University, 1551-7 Taira-machi, Nagasaki, Nagasaki 851-2213, Japan. Electronic address: soyano@nagasaki-u.ac.jp.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Soyano
mesh_terms: D000818:Animals; D005260:Female; D015870:Gene Expression; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*; D007335:Insulin-Like Growth Factor II / Q000235:genetics / Q000378:metabolism*; D006080:Ovarian Follicle / Q000378:metabolism*; D010053:Ovary / Q000378:metabolism*; D010473:Perciformes / Q000235:genetics*
chemical_list: C035170:IGF2 protein, human; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II
keywords: Insulin-like growth factor; Ovarian follicle; Ovary; Reproduction