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Sydney Brenner - One of the best experts on this subject based on the ideXlab platform.
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Characterization of the neurohypophysial hormone gene loci in elephant shark and the Japanese lamprey: origin of the vertebrate neurohypophysial hormone genes.
BMC evolutionary biology, 2009Co-Authors: Paichung Gwee, Boon-hui Tay, Sydney BrennerAbstract:Vasopressin and oxytocin are mammalian neurohypophysial hormones with distinct functions. Vasopressin is involved mainly in osmoregulation and oxytocin is involved primarily in parturition and lactation. Jawed vertebrates contain at least one homolog each of vasopressin and oxytocin, whereas only a vasopressin-family hormone, Vasotocin, has been identified in jawless vertebrates. The genes encoding vasopressin and oxytocin are closely linked tail-to-tail in eutherian mammals whereas their homologs in chicken, Xenopus and coelacanth (Vasotocin and mesotocin) are linked tail-to-head. In contrast, their pufferfish homologs, Vasotocin and isotocin, are located on the same strand of DNA with isotocin located upstream of Vasotocin and separated by five genes. These differences in the arrangement of the two genes in different bony vertebrate lineages raise questions about their origin and ancestral arrangement. To trace the origin of these genes, we have sequenced BAC clones from the neurohypophysial gene loci in a cartilaginous fish, the elephant shark (Callorhinchus milii), and in a jawless vertebrate, the Japanese lamprey (Lethenteron japonicum). We have also analyzed the neurohypophysial hormone gene locus in an invertebrate chordate, the amphioxus (Branchiostoma floridae). The elephant shark neurohypophysial hormone genes encode Vasotocin and oxytocin, and are linked tail-to-head like their homologs in coelacanth and non-eutherian tetrapods. Besides the hypothalamus, the two genes are also expressed in the ovary. In addition, the Vasotocin gene is expressed in the kidney, rectal gland and intestine. These expression profiles indicate a paracrine role for the two hormones. The lamprey locus contains a single neurohypophysial hormone gene, the Vasotocin. The synteny of genes in the lamprey locus is conserved in elephant shark, coelacanth and tetrapods but disrupted in teleost fishes. The amphioxus locus encodes a single neurohypophysial hormone, designated as [Ile4]Vasotocin. The vasopressin- and oxytocin-family of neurohypophysial hormones evolved in a common ancestor of jawed vertebrates through tandem duplication of the ancestral Vasotocin gene. The duplicated genes were linked tail-to-head like their homologs in elephant shark, coelacanth and non-eutherian tetrapods. In contrast to the conserved linkage of the neurohypophysial genes in these vertebrates, the neurohypophysial hormone gene locus has experienced extensive rearrangements in the teleost lineage.
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sequence and organization of coelacanth neurohypophysial hormone genes evolutionary history of the vertebrate neurohypophysial hormone gene locus
BMC Evolutionary Biology, 2008Co-Authors: Paichung Gwee, Chris T Amemiya, Sydney BrennerAbstract:The mammalian neurohypophysial hormones, vasopressin and oxytocin are involved in osmoregulation and uterine smooth muscle contraction respectively. All jawed vertebrates contain at least one homolog each of vasopressin and oxytocin whereas jawless vertebrates contain a single neurohypophysial hormone called Vasotocin. The vasopressin homolog in non-mammalian vertebrates is Vasotocin; and the oxytocin homolog is mesotocin in non-eutherian tetrapods, mesotocin and [Phe2]mesotocin in lungfishes, and isotocin in ray-finned fishes. The genes encoding vasopressin and oxytocin genes are closely linked in the human and rodent genomes in a tail-to-tail orientation. In contrast, their pufferfish homologs (Vasotocin and isotocin) are located on the same strand of DNA with isotocin gene located upstream of Vasotocin gene separated by five genes, suggesting that this locus has experienced rearrangements in either mammalian or ray-finned fish lineage, or in both lineages. The coelacanths occupy a unique phylogenetic position close to the divergence of the mammalian and ray-finned fish lineages. We have sequenced a coelacanth (Latimeria menadoensis) BAC clone encompassing the neurohypophysial hormone genes and investigated the evolutionary history of the vertebrate neurohypophysial hormone gene locus within a comparative genomics framework. The coelacanth contains Vasotocin and mesotocin genes like non-mammalian tetrapods. The coelacanth genes are present on the same strand of DNA with no intervening genes, with the Vasotocin gene located upstream of the mesotocin gene. Nucleotide sequences of the second exons of the two genes are under purifying selection implying a regulatory function. We have also analyzed the neurohypophysial hormone gene locus in the genomes of opossum, chicken and Xenopus tropicalis. The opossum contains two tandem copies of vasopressin and mesotocin genes. The Vasotocin and mesotocin genes in chicken and Xenopus, and the vasopressin and mesotocin genes in opossum are linked tail-to-head similar to their orthologs in coelacanth and unlike their homologs in human and rodents. Our results indicate that the neurohypophysial hormone gene locus has experienced independent rearrangements in both placental mammals and teleost fishes. The coelacanth genome appears to be more stable than mammalian and teleost fish genomes. As such, it serves as a valuable outgroup for studying the evolution of mammalian and teleost fish genomes.
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neurone specific expression and regulation of the pufferfish isotocin and Vasotocin genes in transgenic mice
Journal of Neuroendocrinology, 2003Co-Authors: Patrick Gilligan, Sydney Brenner, Byrappa VenkateshAbstract:We used comparative genetics to investigate the location, structure and evolution of the oxytocin and vasopressin gene regulatory regions. The pufferfish, Fugu rubripes, is an attractive vertebrate model for comparison because of its maximal evolutionary distance from mammals and short intergenic regions. To determine whether regulatory DNA is conserved between oxytocin and vasopressin, and their Fugu homologs, isotocin and Vasotocin, we generated transgenic mice bearing overlapping Fugu cosmids that contained the isotocin and/or Vasotocin genes as well as short isotocin (5 kb) and Vasotocin (9 kb) constructs. Our study shows that the Fugu isotocin and Vasotocin genes express specifically in the mouse oxytocinergic and vasopressinergic neurones, respectively, and that the cis-regulatory elements which mediate neurone-specific expression are located within the short transgene constructs tested. Thus, the neurone-specific expression of the oxytocin and vasopressin gene families, and the mechanisms mediating the cell-specificity, evolved before the divergence of the fish and mammalian lineages. Salt-loading of transgenic mice induced an increase in abundance of isotocin, but not Vasotocin mRNA in the cognate neurones. It appears that either the Vasotocin gene does not respond to osmotic perturbations or the Vasotocin transgene construct tested lacks osmotic response elements. Comparisons of homologous flanking sequences of the Fugu and mouse genes identified several short matching sequences, which are candidate regulatory elements.
Sean C Lema - One of the best experts on this subject based on the ideXlab platform.
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expression profiles of genes encoding arginine Vasotocin and isotocin receptors and the leucyl cystinyl aminopeptidase lnpep nonapeptide degradation enzyme in blue tilapia oreochromis aureus during high salinity acclimation
Marine and Freshwater Behaviour and Physiology, 2020Co-Authors: Jahi K M Abimbola, Jenna M Edwards, Sean C LemaAbstract:The nonapeptide hormone arginine Vasotocin (VT) regulates osmotic balance in fishes by modulating ion and water transport. While VT’s osmoregulatory effects arise in part via changes in VT secretio...
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phylogenetic analysis, sites of expression
2016Co-Authors: Sean C LemaAbstract:Identification of multiple Vasotocin receptor cDNAs in teleost fi sh: Sequences
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arginine Vasotocin isotocin and nonapeptide receptor gene expression link to social status and aggression in sex dependent patterns
Journal of Neuroendocrinology, 2015Co-Authors: Sean C Lema, Kathryn E Sanders, Kayla A WaltiAbstract:Nonapeptide hormones of the vasopressin/oxytocin family regulate social behaviours. In mammals and birds, variation in behaviour also is linked to expression patterns of the V1a-type receptor and the oxytocin/mesotocin receptor in the brain. Genome duplications, however, expand the diversity of nonapeptide receptors in actinopterygian fishes, and two distinct V1a-type receptors (v1a1 and v1a2) for Vasotocin, as well as at least two V2-type receptors (v2a and v2b), have been identified in these taxa. The present study investigates how aggression connected to social status relates to the abundance patterns of gene transcripts encoding four Vasotocin receptors, an isotocin receptor (itr), pro-Vasotocin (proVT) and pro-isotocin (proIT) in the brain of the pupfish Cyprinodon nevadensis amargosae. Sexually-mature pupfish were maintained in mixed-sex social groups and assessed for individual variation in aggressive behaviours. Males in these groups behaved more aggressively than females, and larger fish exhibited higher aggression relative to smaller fish of the same sex. Hypothalamic proVT transcript abundance was elevated in dominant males compared to subordinate males, and correlated positively with individual variation in aggression in both social classes. Transcripts encoding Vasotocin receptor v1a1 were at higher levels in the telencephalon and hypothalamus of socially subordinate males than dominant males. Dominant males exhibited elevated hypothalamic v1a2 receptor transcript abundance relative to subordinate males and females, and telencephalic v1a2 mRNA abundance in dominant males was also associated positively with individual aggressiveness. Transcripts in the telencephalon encoding itr were elevated in females relative to males, and both telencephalic proIT and hypothalamic itr transcript abundance varied with female social status. Taken together, these data link hypothalamic proVT expression to aggression and implicate forebrain expression of the V1a-type receptor v1a2 as potentially mediating the effects of Vasotocin on behaviour in male fish. These findings also illustrate how associations between social status, aggression and gene expression within the VT and IT nonapeptide systems can be contingent on behavioural context.
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identification of multiple Vasotocin receptor cdnas in teleost fish sequences phylogenetic analysis sites of expression and regulation in the hypothalamus and gill in response to hyperosmotic challenge
Molecular and Cellular Endocrinology, 2010Co-Authors: Sean C LemaAbstract:Vasopressin and its homolog Vasotocin regulate hydromineral balance, stress responses, and social behaviors in vertebrates. In mammals, the functions of vasopressin are mediated via three classes of membrane-bound receptors: V1a-type, V1b-type and V2-type. To date, however, only a single class of Vasotocin receptor has been identified in teleost fish. Here, cDNAs encoding three putative Vasotocin receptors – two distinct V1a-type receptor paralogs (V1a1 and V1a2) and a previously undescribed V2-type receptor (V2) – and a single isotocin receptor were isolated and sequenced from the Amargosa pupfish (Cyprinodon nevadensis amargosae). RT-PCR revealed that mRNAs for these receptors differed in expression patterns with V1a1 mRNAs abundant in the brain, pituitary and testis, V1a2 transcripts at greatest levels in brain, heart and muscle, V2 transcripts most common in the gills, heart and kidney, and isotocin receptor mRNAs abundant in the midbrain, pituitary and gonads. In response to an acute hyperosmotic challenge, pro-Vasotocin and V2 mRNA levels in the hypothalamus decreased, while transcripts of V1a1 in the hypothalamus and V1a2 in the gills increased. Partial transcripts for structurally related V2-type, as well as multiple V1a-type, receptors were also identified in other teleosts, suggesting that multiple Vasotocin receptors may be present in many Actinopterygii fishes.
J.m. Warne - One of the best experts on this subject based on the ideXlab platform.
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altered plasma and pituitary arginine Vasotocin and hypothalamic proVasotocin expression in flounder platichthys flesus following hypertonic challenge and distribution of Vasotocin receptors within the kidney
General and Comparative Endocrinology, 2005Co-Authors: J.m. Warne, E. Weybourne, V Sahajpal, R J BalmentAbstract:Plasma AVT concentration, pituitary AVT content, hypothalamic proVasotocin mRNA expression and other osmoregulatory parameters were measured in euryhaline flounder 4, 8, and 24 h after the hypertonic challenge of transfer from fresh water (FW) to seawater (SW). Osmolality and the concentration of major plasma ions, sodium and chloride, were significantly higher in fish transferred to SW by comparison with time matched controls, an effect evident within 4 h. By comparison with time matched controls, pituitary store of AVT was lower while plasma AVT concentration was higher 8 and 24 h after transfer to SW. Higher proVasotocin mRNA expression in the hypothalamus was also seen at 4 and 8 h in flounder transferred from FW to SW compared with time matched controls. The lower pituitary store and higher circulating levels imply substantial AVT secretion occurs in the early phase response to this hypertonic challenge. Changes in the regulation of AVT synthesis and secretion appeared quickly following movement to SW, consistent with the rapid osmoregulatory response, including reduced urine production that fish require to accommodate the dehydrative water losses and salt loading on exposure to the new hyperosmotic environment. qPCR measures of whole kidney Vasotocin receptor mRNA expression indicated similar levels in SW and FW. Immunohistochemistry for the Vasotocin receptor in flounder kidney showed localisation on the afferent and efferent arterioles of the glomerulus and on the capillary bed that extends from the efferent arteriole to the smooth muscle surrounding the collecting duct. Localisation of the Vasotocin receptor was comparable in SW and FW fish.
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Renal Morphology of the Euryhaline Flounder (Platichthys flesus): Distribution of Arginine Vasotocin Receptor.
Annals of the New York Academy of Sciences, 2005Co-Authors: E. Weybourne, J.m. Warne, Marlies Elger, Richard J. BalmentAbstract:The current study characterized tubular segmentation of the European flounder nephron and localized the Vasotocin receptor expression by immunohistochemistry. Flounder nephron was shown to comprise a prominent renal corpuscle, short neck segment, proximal tubule I, proximal tubule II, collecting tubule, and collecting duct. Using specific antibodies raised against flounder Vasotocin receptor, specific V(1) receptor staining was detected within the glomeruli, the endothelial surface of the afferent and efferent arterioles, and the capillaries surrounding the collecting duct system. Immunostaining for the receptor was exclusively vascular and there did not appear to be a tubular component.
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cloning of pro Vasotocin and pro isotocin cdnas from the flounder platichthys flesus levels of hypothalamic mrna following acute osmotic challenge
General and Comparative Endocrinology, 2000Co-Authors: J.m. Warne, K E Harding, R J BalmentAbstract:Sequences coding for pro-Vasotocin and pro-isotocin have been identified by screening a flounder (Platichthys flesus) hypothalamic cDNA library. The 1074-bp proVT and 727-bp proIT sequences contain a signal peptide and hormone, connected to a neurophysin by a Gly-Lys-Arg sequence. Both sequences also have an elongated carboxyl-terminal with a leucine-rich core resembling copeptin but lacking the amino terminal Arg residue. The levels of pro-Vasotocin and pro-isotocin mRNA in the hypothalamus were measured concomitantly with pituitary AVT content and plasma AVT concentration following acute transfer of fish between freshwater and seawater. Three days after transfer from seawater to freshwater there appears to be a down regulation of the AVT hormone system with a fall in hypothalamic pro-Vasotocin mRNA levels, an increase in pituitary AVT content, and a fall in plasma levels, but these changes did not achieve statistical significance compared to controls. No change in the AVT system was detected 3 days following the transfer of fish from freshwater to seawater. Hypothalamic isotocin mRNA levels did not change following hypo- or hyperosmotic challenge.
Roger Acher - One of the best experts on this subject based on the ideXlab platform.
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non mammalian big neurophysins complete amino acid sequence of a two domain msel neurophysin from goose
International Journal of Peptide and Protein Research, 2009Co-Authors: G Michel, Brigitte Lévy, Jacqueline Chauvet, Marie-thérèse Chauvet, Roger AcherAbstract:Vasotocin-associated neurophysin (MSEL-neurophysin) has been purified from goose neurohypophysis through molecular sieving and high-pressure reverse-phase liquid chromatography (HPLC). The protein has a molecular mass (measured by SDS-polyacrylamide gel electrophoresis) of 17 kDa in contrast to 10 kDa found for the mammalian MSEL-neurophysins. Complete amino acid sequence (131 residues) has been determined mainly through tryptic or staphylococcal proteinase peptides derived from carboxyamidomethylated neurophysin, isolated by HPLC and microsequenced. N- and C-terminal sequences have been established by Edman degradation or action of carboxypeptidase Y, respectively, applied on the native protein. Goose MSEL-neurophysin is homologous to the two-domain "big" MSEL-neurophysin previously identified in the frog. It appears that in non-mammalian tetrapods, namely birds and amphibians, the proteolytic processing of the pro-Vasotocin involves only one cleavage, releasing the hormone moiety and a "big" neurophysin with two domains homologous to mammalian MSEL-neurophysin and copeptin, respectively. Comparison of the avian protein with its mammalian and amphibian counterparts reveals that the first half of the polypeptide chain is evolutionarily much less variable than the second and that the goose protein resembles the frog protein much more than the mammalian one.
Vinay Kumar Singh - One of the best experts on this subject based on the ideXlab platform.
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effects of hcg and ovarian steroid hormones on Vasotocin levels in the female catfish heteropneustes fossilis
General and Comparative Endocrinology, 2009Co-Authors: Vinay Kumar SinghAbstract:Abstract Effects of hCG, ovariectomy and estradiol replacement on brain, plasma and/or ovarian Vasotocin in vivo, and estradiol, progesterone, 17α, 20β-hydroxy-4-pregnen-3-one and hCG on ovarian Vasotocin in vitro were investigated in the catfish. A 100 IU/fish of hCG induced ovulation and elicited both periovulatory and post-ovulatory changes in Vasotocin concentrations with a significant increase up to 8 h in the brain and up to 16 h in both plasma and ovary. After stripping the fish at 16 h, the peptide concentration decreased significantly with time, up to 4 days. Ovariectomy in early pre-spawning phase resulted in a duration-dependent significant reduction of both brain and plasma Vasotocin. Estradiol replacement in 3-week ovariectomized fish produced dosage-dependent biphasic effects: the lower dosage (0.1 μg/g) restored the Vasotocin level while the higher dosage (0.5 μg/g) decreased it significantly below the control level. In vitro incubation of ovarian tissues with estradiol produced season-dependent effects on Vasotocin. The incubation of pre-vitellogenic ovarian pieces with estradiol (1, 10, and 100 ng/ml) elevated Vasotocin level in a dose- and duration-dependent manner while that of post-vitellogenic follicles resulted in a significant decrease. The incubation of intact post-vitellogenic follicles or follicular envelope with progesterone and 17α, 20β-hydroxy-4-pregnen-3-one (1 μg/ml) or hCG (20 IU/ml) for 8 and 16 h significantly increased Vasotocin in a duration-dependent manner. The results show that both gonadotropin and ovarian steroids modulate Vasotocin titer, which may influence follicular growth, ovulation and spawning in the catfish.
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immunocytochemical localization hplc characterization and seasonal dynamics of Vasotocin in the brain blood plasma and gonads of the catfish heteropneustes fossilis
General and Comparative Endocrinology, 2008Co-Authors: Vinay Kumar SinghAbstract:Abstract Immunocytochemical distribution and dynamics of Vasotocin (VT) were studied in the air-breathing catfish Heteropneustes fossilis in relation to the reproductive cycle. Vasotocin was localized in the brain and ovary by streptavidin–biotin immunocytochemistry. The immunoreactivity was found throughout the hypothalamo–hypophysial neurosecretory system consisting of the magnocellular and parvocellular neurons of the nucleus preopticus, neurosecretory axonal tract and neurohypophysis (NH). The VT neurons showed seasonal changes; they were numerically less in resting phase but increased during the recrudescent phase. The neurons were hypertrophied and degranulated in pre-spawning phase and heavily degranulated and vacuolated in spawning phase. In the NH, the density of VT fibers increased up to the pre-spawning phase and decreased thereafter. In the ovary, VT immunoreactivity was noticed in the follicular layer and varied with the growth of the follicles. Vasotocin was characterized and quantified by a high performance liquid chromatography with UV detection method in the brain, plasma and ovary. Brain and plasma VT concentrations were also assayed with an EIA method, which was more sensitive than the HPLC method with values about 2-fold higher. Vasotocin levels showed significant seasonal and sexual differences with higher concentrations in females in the recrudescent (preparative, pre-spawning and spawning) phase. Brain VT recorded the highest concentration in the preparative phase (both sexes) while plasma (both sexes) and ovarian VT in the spawning phase. The ovarian concentration of VT was 15- and 25-fold higher in the pre-spawning and spawning phases (when expressed per mg protein), respectively, than plasma but lower than brain levels. In testis, VT concentration was relatively low and apparently did not show any significant seasonal variation. The seasonal activity patterns and gonadal distribution of VT indicate a reproductive function of the peptide.
