@article{weber_king_clark_hodson_sullivan_2000, title={Morpho-physiological predictors of ovulatory success in captive striped bass (Morone saxatilis)}, volume={188}, ISSN={["1873-5622"]}, DOI={10.1016/S0044-8486(00)00328-8}, abstractNote={This study evaluates morpho-physiological characters as predictors of ovulatory success in cultured striped bass, Morone saxatilis, that could be used by farmers to select females for induced spawning. Diameter, size homogeneity and growth of ovarian follicles; blood plasma levels of testosterone (T), oestradiol-17β (E2) and vitellogenin (VTG); and in vitro maturation of oocytes, in response to a combination of insulin-like growth factor-I (IGF-I, 100 nM) and 17,20β,21-trihydroxy-4-pregnen-3-one (20β-S, 290 nM) were examined for females prior to spawning induction and compared with their subsequent ovulatory response. Fish spawning within 8 days of implantation with pelleted analogue of mammalian gonadotropin-releasing hormone analogue (GnRHa; [d-Ala6-des-Gly10-NEt]-LHRH) were considered to have given a satisfactory maturational response. The in vitro assay was the most reliable predictor for ovulatory success. All fish whose oocytes completed final oocyte maturation (FOM) in vitro in response to the combination of IGF-I and 20β-S spawned, whereas, 12 out of 13 fish, whose oocytes did not complete FOM in vitro, failed to spawn within 8 days of GnRHa treatment. The in vitro assay was field-tested on commercial farms, and correctly identified all four females that spawned out of the eight females that were given hormone treatment. Among the other measurements, follicle diameter best differentiated between fish that later spawned and those that did not spawn. Plasma T concentrations were greater on average in fish that spawned, but the technical complexity of the assay and overlap in T concentrations between fish that spawned and those that did not limits the value of this measurement to farmers. There was no significant difference in follicle size homogeneity, follicle growth over the 2-week period prior to hormone treatment, or plasma levels of E2 and VTG between fish that spawned and those that did not.}, number={1-2}, journal={AQUACULTURE}, author={Weber, GM and King, W and Clark, RW and Hodson, RG and Sullivan, CV}, year={2000}, month={Aug}, pages={133–146} }
 @article{roberts_jackson_king_taylor_grier_sullivan_1999, title={Annual reproductive cycle of the common snook: Endocrine correlates of maturation}, volume={128}, ISSN={["1548-8659"]}, DOI={10.1577/1548-8659(1999)128<0436:ARCOTC>2.0.CO;2}, abstractNote={Abstract Wild common snook Centropomus undecimalis were captured off the Gulf coast of Florida over a 2-year period and sampled for serum and gonad tissue to characterize their annual reproductive cycle. During the summer months, levels of the sex steroid hormones estradiol-17β (E2) and testosterone (T) in females were significantly elevated above basal winter values. Mean gonadosomatic index (GSI) was also significantly elevated in females during summer. In addition, fish whose ovaries contained oocytes in vitellogenic and final maturation stages had elevated levels of alkali-labile protein phosphorus (ALPP), an indirect measure of the egg yolk precursor, vitellogenin. Peak levels of E2, T, and ALPP were measured in females during the spawning season (late summer) when GSI was also maximal. Circulating levels of T and 11-ketotestosterone (11-KT) in males were also higher in the summer months than at any other time of the year. Males showed an increase in GSI over basal winter values during the summer mon...}, number={3}, journal={TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY}, author={Roberts, SB and Jackson, LF and King, W and Taylor, RG and Grier, WJ and Sullivan, CV}, year={1999}, month={May}, pages={436–445} }
 @article{king_ghosh_thomas_sullivan_1997, title={A receptor for the oocyte maturation-inducing hormone 17 alpha,20 beta,21-trihydroxy-4-pregnen-3-one on ovarian membranes of striped bass}, volume={56}, ISSN={["0006-3363"]}, DOI={10.1095/biolreprod56.1.266}, abstractNote={Previous studies have shown that blood plasma levels of 17alpha, 20beta-dihydroxy-4-pregnen-3-one (DHP) and 17alpha, 20beta, 21-trihydroxy-4-pregnen-3-one (20beta-S) increase in striped bass (Morone saxatilis) undergoing final oocyte maturation (FOM). Both hormones are produced by ovarian fragments undergoing hCG-induced germinal vesicle breakdown (GVBD) in vitro. In the present study, we investigated binding of DHP and 20beta-S to ovarian membranes from striped bass undergoing FOM. Saturable binding sites for DHP were not detected. Saturation of 20beta-S binding sites with 5 nM [3H]20beta-S occurred within 40 min at 0 degrees C (at 3 min, half of the maximum specific binding of steroid was calculated to have occurred), and the binding was pH-dependent. Scatchard analyses revealed the presence of a single class of high-affinity (dissociation constant [Kd] = 1.4 +/- 0.2 nM), limited-capacity (estimated concentration [Bmax] = 2.7 +/- 0.3 pmol/g ovary) 20beta-S binding sites on membranes from striped bass ovaries undergoing FOM. In contrast, only low levels of specific binding (Bmax < 0.04 pmol/g tissue) were detected on membranes from testes, liver, brain, and muscle. Ovarian membranes prepared from vitellogenic females also had low levels (Bmax < 0.1 pmol/g ovary) of specific 20beta-S binding, less than 5% of that found during FOM. Results of competition assays showed that DHP was approximately 250 times less effective than 20beta-S for displacing 20beta-S from ovarian membranes. In contrast, 20beta, 21-dihydroxy-4-pregnen-3-one was a very effective competitor, although it is only a weak inducer of oocyte GVBD in vitro. Of several other steroids tested, only progesterone showed affinity for the 20beta-S binding site within a physiological range of concentrations. Taken together with previous studies of striped bass FOM, these findings indicate that 20beta-S is the oocyte maturation-inducing steroid hormone in striped bass.}, number={1}, journal={BIOLOGY OF REPRODUCTION}, author={King, W and Ghosh, S and Thomas, P and Sullivan, CV}, year={1997}, month={Jan}, pages={266–271} }
 @article{king_berlinsky_sullivan_1995, title={Involvement of gonadal steroids in final oocyte maturation of white perch (Morone americana) and white bass (M-chrysops): In vivo and in vitro studies}, volume={14}, ISSN={["0920-1742"]}, DOI={10.1007/BF00004349}, abstractNote={Plasma estradiol-17β (E2), testosterone (T), 17α,20β-dihydroxy-4-pregnen-3-one (DHP) and 17α,20β,21-tri-hydroxy-4-pregnen-3-one (20β-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20β-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E2 and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20β-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E2 and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20β-S and oocyte GVBD by white perch follices. DHP and 20β-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20β-S in the control of FOM in white perch and white bass.}, number={6}, journal={FISH PHYSIOLOGY AND BIOCHEMISTRY}, author={King, W and Berlinsky, DL and Sullivan, CV}, year={1995}, month={Dec}, pages={489–500} }
 @article{king_thomas_sullivan_1994, title={HORMONAL-REGULATION OF FINAL MATURATION OF STRIPED BASS OOCYTES IN-VITRO}, volume={96}, ISSN={["1095-6840"]}, DOI={10.1006/gcen.1994.1177}, abstractNote={An in vitro culture system was developed to investigate hormonal control of final oocyte maturation (FOM) in striped bass (Morone saxatilis). Isolated ovarian fragments exposed to human chorionic gonadotropin (hCG), dibutyryl cAMP, or forskolin produced significant amounts of 17 alpha,20 beta-dihydroxy-4-pregnen-3-one (DHP) and the oocytes underwent germinal vesicle breakdown (GVBD). Slight increases in 17 alpha,20 beta,21-trihydroxy-4-pregnen-3-one (20 beta-S) production were also observed. Production of testosterone and estradiol-17 beta was relatively high at the beginning of in vitro treatment with hCG but decreased as production of DHP increased and GVBD was initiated. Inhibitors of protein transcription (actinomycin-D), translation (cycloheximide), and steroidogenesis (trilostane) completely blocked hCG-induced DHP and 20 beta-S production and the associated GVBD. FOM, assessed from the progress of GVBD, proceeded in trilostane-treated but not in cycloheximide-treated follicle-enclosed oocytes when DHP or 20 beta-S was added to the cultures. Structure-activity experiments revealed that DHP and 20 beta-S were more potent at inducing GVBD than 14 other structurally similar C21 steroids that were tested. These results demonstrate that FOM in striped bass is induced by gonadotropin-mediated production of a delta 4 steroid through an adenylate-cyclase pathway which requires protein synthesis. DHP and 20 beta-S are implicated as final oocyte maturation-inducing steroid hormones in striped bass.}, number={2}, journal={GENERAL AND COMPARATIVE ENDOCRINOLOGY}, author={KING, W and THOMAS, P and SULLIVAN, CV}, year={1994}, month={Nov}, pages={223–233} }
 @article{king_thomas_harrell_hodson_sullivan_1994, title={PLASMA-LEVELS OF GONADAL-STEROIDS DURING FINAL OOCYTE MATURATION OF STRIPED BASS, MORONE-SAXATILIS L}, volume={95}, ISSN={["0016-6480"]}, DOI={10.1006/gcen.1994.1115}, abstractNote={Levels of estradiol-17 beta (E2), testosterone (T), 17 alpha,20 beta-dihydroxy-4-pregnen-3-one (DHP), and 17 alpha,20 beta,21-trihydroxy-4-pregnen-3-one (20 beta-S) were measured by radioimmunoassay (RIA) in blood plasma of striped bass undergoing final oocyte maturation (FOM). Females were captured just prior to, or in the early stages of, FOM and induced to complete maturation and ovulation with injected human chorionic gonadotropin, synthetic salmon gonadotropin-releasing hormone analogue (sGnRHa; [D-Arg6-Pro9 NEt]-sGnRH), sGnRHa plus the dopamine receptor antagonist, domperidone (DOM), or OVAPRIM, a commercial preparation of sGnRHa + DOM. Their plasma levels of immunoreactive DHP and 20 beta-S were significantly greater at ovulation relative to the time of hormone injection, whereas the plasma levels of E2 and T were greatest at injection and decreased by ovulation and 24 hr thereafter. Plasma levels of 20 beta-S, but not DHP, were sustained at high levels after ovulation. Fish injected only with DOM did not undergo FOM, its associated changes in plasma steroid levels, or ovulation. In females captured at various natural stages of FOM, plasma levels of 20 beta-S and DHP were low during germinal vesicle migration (GVM), peaked coincident with germinal vesicle breakdown, and then decreased near the time of ovulation. Plasma levels of E2 and T were greatest during GVM and decreased as DHP and 20 beta-S levels increased. Analyses of conjugated versus free plasma steroids showed 64-79% of the various hormones to be in the free fraction. RIA of plasma fractionated by reversed-phase HPLC showed that half of the 20 beta-S immunoreactivity coeluted with 5 beta-pregnan-3 alpha,17,20 beta,21-tetrol, a putative 20 beta-S metabolite with 99.7% cross-reactivity in the 20 beta-S RIA. These results indicate that striped bass follow the typical profile of changing plasma steroid levels seen in other teleosts during FOM, with a clear shift from C18 and C19 steroids to C21 steroids. They suggest that both DHP and 20 beta-S, both potent inducers of striped bass FOM in vitro, may play a role in regulating FOM in this species.}, number={2}, journal={GENERAL AND COMPARATIVE ENDOCRINOLOGY}, author={KING, W and THOMAS, P and HARRELL, RM and HODSON, RG and SULLIVAN, CV}, year={1994}, month={Aug}, pages={178–191} }