The objectives of this study were to characterize multiple forms of vitellogenin (Vg) in mosquitofish (Gambusia affinis) and to discover the fate of each Vg during its processing into product yolk proteins. Two Vg preparations, with apparent masses of 600 kDa (600 Vg) and 400 kDa (400 Vg), were isolated from the plasma of fish treated with estradiol-17beta (E(2)) by various chromatographic procedures. Immunological analyses verified the presence of two different Vg proteins (600 VgA and 600 VgB) in the 600 Vg preparation and of a single protein in the 400 Vg preparation. Three major yolk proteins (Yps) with apparent masses of 560, 400, and 28 kDa were observed in extracts of ovarian follicles from vitellogenic females. Immunological analyses demonstrated that the 400 Vg underwent no change in native mass after being incorporated into oocytes. The 600 Vgs gave rise to a 28 kDa beta'-component and a native 560 kDa Yp, which was heterodimeric in structure, consisting of two types of complexes between phosvitin (Pv) and lipovitellin (Lv) heavy- and light-chains. Full-length cDNAs encoding the 600 VgA, 600 VgB, and 400 Vg were isolated from a liver cDNA library of E(2) treated fish. Similar to the zebrafish vg3 gene, the 400 Vg cDNA lacked a Pv domain and was classified as an incomplete or phosvitinless (C-type) Vg. The deduced primary structures of 600 VgA and 600 VgB were complete, and these were categorized as type A and type B Vgs, respectively, according to our recent classification scheme. This is the first report on the characterization of three functional Vg genes and their circulating and yolk protein products in any vertebrate species.

The gonadal development and serum profiles of vitellogenin and sex steroids in rearing Sebastes schlegeli were monitored for one full year. Female fish began vitellogenesis from November and completed it in March. Gestation occurred from April, and parturition occurred in June. A thin chorion and scanty cortical alveoli are oogenetic peculiarities of this fish. Male fish began spermatogenesis from June, and matured in November and December. It appears that copulation occurs in November and December, and that the sperm are stored freely in the ovary during the early vitellogenic period and under the ovigerous lamellae epithelium during the late vitellogenic period. Serum vitellogenin levels in female fish had a good correlation with oocyte growth. Serum estradiol‐17β (E2) levels in female fish were elevated from November to February, suggesting that E2 controls vitellogenesis. Serum 17,20β‐dihydroxy‐4‐pregnen‐3‐one (DHP) in female fish increased in the late vitellogenic period, suggesting that DHP was a maturation‐inducing steroid. High levels of serum DHP during gestation suggest that it may be one of the endocrine factors for maintaining gestation. Serum 11‐ketotestosterone (11‐KT) levels in male fish were elevated from June to October, suggesting that 11‐KT controls spermatogenesis. Serum DHP in male fish had a single peak in October, suggesting that DHP plays some role in the late stages of spermatogenesis.

No abstract

The reproductive modes of the Scorpaenidae are extremely varied: oviparity, viviparity, and even spawning of internally fertilized eggs or embryos (zygoparity or embryoparity), as in Helicolenus, are known. The ovarian structure of this family is divided into two types by the arrangement of the stroma and the ovarian cavity. One type is the ovary in which the lamella-like stroma develops from the ovarian hilus located on the dorsal side and where the ovarian cavity is located on the ventral side of ovary, classifi ed as "cystovarian type II-1" by Takano (1989). In the other type, the stroma in the ovary develops radially around the blood circulatory system that traverses the center of the ovary, and then the ovarian cavity surrounds all the ovary, classifi ed as "cystovarian type II-3" by Takano (1989). In the present analysis, previous reports about ovarian structure and the relationship to the reproductive mode of scorpaenids were described, and the ovarian structure of eight genera of Scorpaenidae was examined. The ovary of cystovarian type II-1 is seen only in viviparous genera and is not seen in oviparous genera. However, the cystovarian type II-1 is a general structure in other families of Scorpaeniformes, and this structure could be considered a primitive type of ovary rather than that acquired by the process of evolution from oviparity to viviparity. The ovary of cystovarian type II-3 is seen in all six oviparous genera and the one zygoparous genus examined. The ovary of this type is not found in any other family of teleosts, so it could be a structure originally divided in Scorpaenidae. In the genera having the cystovarian type II-3 ovary, there is a common feature of spawning: a fl oating egg mass encompassed by the gelatinous material. We postulate that the evolution of reproductive mode in the scorpaenid fi shes is as follows: Sebastes and Sebastiscus have a primitive ovary in which viviparity has developed, whereas the genera that spawn a fl oating egg mass evolved the ovarian structure from primitive type to cystovarian type II-3, and further zygoparity, such as in Helicolenus, evolved from them.

No abstract