Steroid and thyroid hormones during sexual maturation of coho salmon (Oncorhynchus kisutch) in seawater of fresh water.
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Androgens↗
Biomedical subjects
S A Sower
Publications and source records attributed to S A Sower.
Effects of pond water, sediment and sediment extract samples from New Hampshire, USA on early Xenopus development and metamorphosis: comparison to native species.
In an effort to assess potential ecological hazards to amphibian species in selected regions within New Hampshire, the traditional Frog Embryo Teratogenesis Assay-Xenopus (FETAX), a 14-/21 day tail resorption thyroid disruption assay and >30 day limb development tests were conducted with representative surface water and sediment samples. Two separate sets of samples collected from five sites were evaluated. The primary objectives of the study were to determine if samples were capable of inducing early embryo-larval maldevelopment, to determine if maldevelopment included limb defects, to determine if thyroxine co-administration altered the rates of limb malformation and to evaluate the impact of the samples on growth rates, developmental progress and metamorphic climax. Results from these studies suggested that pond water and sediment extract samples, but not whole sediment samples, from B2, FW, LP and W ponds were capable of inducing abnormal early embryo-larval development. In addition, water samples from B2 and W ponds induced significant abnormal hindlimb development. Some abnormal forelimb development was noted in the tail resorption studies, but not to the same extent as the hindlimbs. Each of the water samples induced appreciable developmental delay, including the paired reference site B1, which could be reversed by the addition of exogenous thyroxine.
Animals↗
Polygenic expression of gonadotropin-releasing hormone (GnRH) in human?
A non-mammalian lamprey-like gonadotropin-releasing hormone (lGnRH) has been detected in human hypothalami using a combination of immunocytochemistry, high performance liquid chromatography and radioimmunoassay. The hypothalamic distribution of immunopositive lGnRH neurons is similar to that observed for those containing the mammalian gonadotropin-releasing hormone (mGnRH), indicating a possible role for this newly identified peptide in the regulation of pituitary function. Our data suggest the existence of a separate gene for lamprey-like GnRH in humans. Confirmation of the exact nature and role of this newly detected form of GnRH will require future isolation and sequence analysis. The possibility that polygenic expression of a given peptide may be a common phenomenon even in higher mammals is discussed.
Adult↗
Multiple molecular forms of gonadotropin-releasing hormone in the brain of an elasmobranch: evidence for IR-lamprey GnRH.
These studies investigated brains of skate, Raja erinacea (order Rajiformes, class Chondrichthyes), for gonadotropin-releasing hormone (GnRH) peptides by chromatograph and immunoreactivity with region-specific antisera raised against mammalian GnRH and lamprey GnRH. The region-specific antibody to lamprey GnRH-I was produced following conjugation to bovine serum albumin using the bis-diazotized benzidine method. This antibody was characterized by assaying a range of increasing dilutions of the known vertebrate GnRHs, as well as analogs to lamprey GnRH-I. Two analogs, lamprey [Phe2]GnRH-I and lamprey [Leu7]GnRH-I, were synthesized by solid phase peptide synthesis using a benzhydrylamine resin as the supporting medium and purified by chromatography. This antibody demonstrated less than 0.01% cross-reactivity with all GnRH peptides tested, suggesting a highly specific antibody with a region of amino acids 2-8 that appears essential for binding. In the skate brain, five immunoreactive (IR) GnRH forms were detected, four of which eluted in the same positions as synthetic mammal and chicken GnRH-I (which coelute): lamprey GnRH-I, salmon and chicken GnRH-II, and one that was an unidentified form. A minor peak coeluted with lamprey GnRH-III. The major form in the skate brain is considered to have eluted with synthetic mammalian GnRH. These studies confirm an earlier report of an IR-mammalian GnRH peptide and provide new evidence for IR-lamprey GnRH in the brain of an elasmobranch.
Animals↗
Isolation and characterization of melanotropins from lamprey pituitary glands.
Three peptides containing the melanotropin-core amino-acid sequence, YXMXHFRWG, were isolated from the pituitary glands of a modern representative of the most primitive vertebrates, the sea lamprey, Petromyzon marinus. MSH-A, a nonadecapeptide (NPELYQMNHFRWGQPPTHF), is free at both ends. MSH-B, an eicosapeptide (VQESADGYRMQHFRWGQPLP), is free at the N-terminus and amidated at the C-terminus. They differ strikingly from gnathostome MSHs in structure. The third peptide, with an apparent molecular weight of 15 kDa, was tentatively designated lamprey ACTH, based on a structural feature: the N-terminal 22-residue-MSH (SVSSPKYAMGHFRWGSPDKATI) is followed by four consecutive basic amino acids (RKRR) and a ACTH-like sequence (PVRPNTSDSPEIPDYAF--). MSH-B is 10 and 100 times more potent than alpha-MSH and MSH-A, respectively, in a frog skin assay in vitro, whereas the lamprey ACTH showed no melanotropic activity. Lamprey ACTH did, however, show corticotropic activity on the lamprey pronephric and mesonephric tissue.
Adrenal Glands↗