| organization of peripheral nerves and spinal roots of the atlantic stingray, dasyatis sabina. | 1. the sizes and numbers of axons in peripheral nerves and spinal roots were investigated in the stingray, dasyatis sabina. 2. the axons of the dorsal and ventral roots do not mingle in peripheral nerves of this animal as they do in higher vertebrates. thus, it was usually possible to split the peripheral nerve into two portions, one containing only dorsal root axons, the other containing only ventral root axons. this feature was useful for the analysis of certain aspects of spinal cord organiza ... | 1978 | 621549 |
| free amino acids in tissues of the skate raja erinacea and the stingray dasyatis sabina: effects of environmental dilution. | concentrations of individual free amino acids were determined in various tissues of the skate (raja erinacea) and the stingray (dasyatis sabina), and the relationship of cellular free amino acid concentrations to intracellular osmoregulation was investigated by adapting these elasmobranchs to half-strength seawater. each tissue characteristically had high levels of certain specific amino acids. skate sing muscle contained high concentrations of sarcosine and beta-alanine, skate heart had high co ... | 1977 | 850123 |
| a comparison of the effects of mammalian tsh on the thyroid glands of the teleost galeichthys felis and the elasmobranch dasyatis sabina. | | 1973 | 4145427 |
| organization of spinal motor nuclei in the stingray, dasyatis sabina. | the atlantic stingray, dasyatis sabina, has enlarged pectoral fins consisting of a series of antagonist dorsal (elevator) and ventral (depressor) muscles. each muscle is divided into superficial and deep components. the retrograde transport of horseradish peroxidase (hrp) was used to determine the organization of motoneuron pools innervating fin and epaxial muscles. hrp applied to a single peripheral nerve labeled motoneurons within a single spinal segment. following intramuscular injection of h ... | 1983 | 6627006 |
| spinal cord pathways involved in initiation of swimming in the stingray, dasyatis sabina: spinal cord stimulation and lesions. | in spinally transected stingrays, electrical stimulation of a site just ventral to the dorsal root entry zone or a site in the intermediate portions of the lateral funiculus produced rhythmic swimming like movements of the contralateral pectoral fin. electromyographic (emg) records collected during cord-stimulated rhythms had the same pattern of activity and sometimes the same intersegmental coordination as those collected during spontaneous swimming of the same animal. in paralyzed, high-spinal ... | 1984 | 6699678 |
| identification of gastric h,k-atpase in an early vertebrate, the atlantic stingray dasyatis sabina. | virtually all vertebrates acidify their gastric contents to a ph between 0.8 and 2.0. in mammals, acid secretion is mediated by a k-stimulated proton-translocating adenosine triphosphatase (h,k-atpase), which establishes a million-fold gradient of protons across the apical membrane of the gastric parietal cell. the earliest phylogenetic appearance of gastric acid secretion is in cartilaginous fish, and we sought to verify in this class (chondrichthyes) the presence and distribution of h,k-atpase ... | 1994 | 7930514 |
| urea transport by hepatocytes and red blood cells of selected elasmobranch and teleost fishes | although urea transport is receiving increased attention in mammalian systems, very little is known about urea transport in fish tissues. this study examined mechanisms of urea transport in red blood cells and hepatocytes from the lesser spotted dogfish (scyliorhinus canicula), atlantic stingray (dasyatis sabina), turbot (scopthalmus maximus), redfish (scianops ocellatus), gulf toadfish (opsanus beta) and oyster toadfish (opsanus tau). urea appeared to be passively distributed in both tissues (i ... | 1994 | 9317893 |
| regulation of interrenal gland steroidogenesis in the atlantic stingray (dasyatis sabina). | the interrenal gland (the homologue of the mammalian adrenal cortex) of elasmobranchs (sharks, skates, and rays) produces 1alpha-hydroxycorticosterone (1alpha-b), which has been reported to function both as a gluco- and mineralocorticosteroid. in vitro synthesis of 1alpha-b by atlantic stingray (dasyatis sabina) interrenal glands was stimulated by short-term (2 hr) and long-term (24 hr) treatment with porcine adrenocorticotropic hormone (pacth). cycloheximide blocked the pacth-induced effect on ... | 1999 | 10469989 |
| differential distribution of gonadotropin-releasing hormone-immunoreactive neurons in the stingray brain: functional and evolutionary considerations. | gonadotropin-releasing hormone (gnrh) is a neuropeptide that occurs in multiple structural forms among vertebrate species. bony fishes, amphibians, reptiles, birds, and mammals express different forms of gnrh in the forebrain and endocrine regions of the hypothalamus which regulate the release of reproductive gonadotropins from the pituitary. in contrast, previous studies on bony fishes and tetrapods have localized the chicken gnrh-ii (cgnrh-ii) nucleus in the midbrain tegmentum and, combined wi ... | 2000 | 10890564 |
| pectoral fin locomotion in batoid fishes: undulation versus oscillation. | this study explores the dichotomy between undulatory (passing multiple waves down the fin or body) and oscillatory (flapping) locomotion by comparing the kinematics of pectoral fin locomotion in eight species of batoids (dasyatis americana, d. sabina, d. say, d. violacea, gymnura micrura, raja eglanteria, rhinobatos lentiginosus and rhinoptera bonasus) that differ in their swimming behavior, phylogenetic position and lifestyle. the goals of this study are to describe and compare the pectoral fin ... | 2001 | 11136623 |
| european sea bass (dicentrarchus labrax l.) cytochrome p450arom: cdna cloning, expression and genomic organization. | cytochrome p450arom, a key enzyme in the hormonal steroidogenic pathway, mediates the conversion of androgens to estrogens. this work describes the molecular cloning of the cdna encoding the european sea bass (dicentrarchus labrax l.) cytochrome p450arom by means of reverse transcriptase and polymerase chain reaction (rt-pcr) and 5' and 3'-rapid amplification of cdna ends (race) analyses. the cdna is 1822bp in length and encodes a putative protein of 517 amino acids. northern blot analysis revea ... | 2002 | 11867261 |
| pendrin immunoreactivity in the gill epithelium of a euryhaline elasmobranch. | pendrin is an anion exchanger in the cortical collecting duct of the mammalian nephron that appears to mediate apical cl(-)/hco3(-) exchange in bicarbonate-secreting intercalated cells. the goals of this study were to determine 1) if pendrin immunoreactivity was present in the gills of a euryhaline elasmobranch (atlantic stingray, dasyatis sabina), and 2) if branchial pendrin immunoreactivity was influenced by environmental salinity. immunoblots detected pendrin immunoreactivity in atlantic stin ... | 2002 | 12228069 |
| a thromboxane a(2) system in the atlantic stingray, dasyatis sabina. | thromboxane b(2)(txb(2)) is the stable metabolite of thromboxane a(2)(txa(2)) and thromboxane b(2)-like immunoreactivity (itxb(2)) has been identified in the plasma of the atlantic stingray, dasyatis sabina (0.57+/-0.03 ng/ml). plasma levels of itxb(2) increase if the blood is allowed to clot (3.0+/-0.27 ng/ml). when clotting occurs in the presence of indomethacin, this increase is partially inhibited (1.5+/-0.17 ng/ml), indicating the presence of a cyclooxygenase activity. radioligand binding a ... | 2003 | 12568793 |
| nhe3 in an ancestral vertebrate: primary sequence, distribution, localization, and function in gills. | in mammals, the na+/h+ exchanger 3 (nhe3) is expressed with na+/k+-atpase in renal proximal tubules, where it secretes h+ and absorbs na+ to maintain blood ph and volume. in elasmobranchs (sharks, skates, and stingrays), the gills are the dominant site of ph and osmoregulation. this study was conducted to determine whether epithelial nhe homologs exist in elasmobranchs and, if so, to localize their expression in gills and determine whether their expression is altered by environmental salinity or ... | 2005 | 15994375 |
| regulation of mrnas encoding the steroidogenic acute regulatory protein and cholesterol side-chain cleavage enzyme in the elasmobranch interrenal gland. | the rate-limiting and regulated step in steroidogenesis, the conversion of cholesterol to pregnenolone, is facilitated by the steroidogenic acute regulatory protein (star) and cytochrome p450 cholesterol side-chain cleavage (p450scc). we have isolated cdnas encoding star and p450scc from the atlantic stingray, dasyatis sabina, and characterized the steroidogenic activity of the encoded proteins using a heterologous expression system. green monkey kidney (cos-1) cells cotransfected with d. sabina ... | 2010 | 20417210 |
| a voltage-clamp study of isolated stingray horizontal cell non-nmda excitatory amino acid receptors. | 1. horizontal cells enzymatically isolated from retinas of the atlantic stingray (dasyatis sabina) were voltage-clamped using the patch electrode in the whole-cell mode. a rapid microsuperfusion system was used to apply excitatory amino acid agonists and antagonists. 2. the isolated cells responded to glutamate (glu), kainate (ka), quisqualate (qa) and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (ampa). responses elicited by glu, qa, and ampa but not ka exhibited a concentration-dep ... | 2006 | 2563761 |
| osmoregulation in the euryhaline elasmobranch, dasyatis sabina. | | 2014 | 4145709 |
| immunohistochemical localization of urotensin i/corticotropin-releasing factor, urotensin ii, and serotonin immunoreactivities in the caudal spinal cord of nonteleost fishes. | neurosecretory cells in the caudal spinal cord of fishes were first discovered in elasmobranches. however, most of the subsequent work on the caudal neurosecretory system has emphasized its morphology and function in teleosts. two major peptides, urotensins i and ii (ui and uii), have been isolated from this system in teleosts and their amino acid sequences have been determined. we have used immunohistochemical techniques to confirm and expand previous morphological and pharmacological findings ... | 1986 | 3525617 |
| vestibulo-oculomotor connections in an elasmobranch fish, the atlantic stingray, dasyatis sabina. | in elasmobranch fishes, including the atlantic stingray, the medial rectus muscle is innervated by the contralateral oculomotor nucleus. this is different from most vertebrates, in which the medial rectus is innervated by the ipsilateral oculomotor nucleus. this observation led to the prediction that the excitatory vestibulo-extraocular motoneuron projections connecting each semicircular canal to the appropriate muscle should use a contralateral projection from the vestibular nuclei to the moton ... | 1994 | 8144748 |
| the octavolateral systems in the stingray, dasyatis sabina. i. primary projections of the octaval and lateral line nerves. | the central projections of the electrosensory, mechanosensory, and octaval nerves of the atlantic stingray were examined by transganglionic transport of horseradish peroxidase. particular attention was paid to the relation of the projections to cell plates c1 and c2, and to a newly described cell plate, c3. the electroreceptors in the stingray are found in three groups on the dorsal and ventral sides of the body. the electroreceptors are represented topographically on the ipsilateral dorsal nucl ... | 1993 | 8514920 |
| urea based osmoregulation and endocrine control in elasmobranch fish with special reference to euryhalinity. | since the landmark contributions of homer smith and co-workers in the 1930s there has been a considerable advance in our knowledge regarding the osmoregulatory strategy of elasmobranch fish. smith recognised that urea was retained in the body fluids as part of the 'osmoregulatory ballast' of elasmobranch fish so that body fluid osmolality is raised to a level that is iso- or slightly hyper-osmotic to that of the surrounding medium. from studies at that time he also postulated that many marine dw ... | 2003 | 14662294 |
| immunohistochemical localization of renin-containing cells in two elasmobranch species. | renin immunoreactivity was localized at the light and electron microscopic level in two elasmobranch fish species, the atlantic stingray, dasyatis sabina, and river ray, potamotrygon humerosa. at the light microscopic level, the peroxidase-anti-peroxidase method showed a positive immunoreactivity in modified smooth muscle cells in kidney afferent arterioles as well as in arterioles of several organs: rectal gland, inter-renal gland, conus arteriosus, and gill. electron microscopic renin-positive ... | 2016 | 26746846 |
| fresh water acclimation elicits a decrease in plasma corticosteroids in the euryhaline atlantic stingray, dasyatis sabina. | it is thought that the elasmobranch corticosteroid hormone 1α-hydroxycorticosterone (1α-b) functions as both a glucocorticoid (gc) and mineralocorticoid (mc). classical antinatriuretic mc activities would run counter to the osmoregulatory strategy of euryhaline elasmobranchs acclimating to fresh water (fw). therefore we hypothesize that fw acclimation will be accompanied by a decrease in plasma corticosteroids in these animals. however, events that activate the "fight-or-flight" response could m ... | 2015 | 26315386 |
| biomechanical model of batoid (skates and rays) pectoral fins predicts the influence of skeletal structure on fin kinematics: implications for bio-inspired design. | growing interest in the development of bio-inspired autonomous underwater vehicles (auvs) has motivated research in understanding the mechanisms behind the propulsion systems of marine animals. for example, the locomotive behavior of rays (batoidea) by movement of the pectoral fins is of particular interest due to their superior performance characteristics over contemporary auv propulsion systems. to better understand the mechanics of pectoral fin propulsion, this paper introduces a biomechanica ... | 2015 | 26079094 |
| stability design and response to waves by batoids. | unsteady flows in the marine environment can affect the stability and locomotor costs of animals. for fish swimming at shallow depths, waves represent a form of unsteady flow. waves consist of cyclic oscillations, during which the water moves in circular or elliptical orbits. large gravity waves have the potential to displace fish both cyclically and in the direction of wave celerity for animals floating in the water column or holding station on the bottom. displacement of a fish can exceed its ... | 2015 | 26060212 |
| na⁺/k⁺-atpase α1 mrna expression in the gill and rectal gland of the atlantic stingray, dasyatis sabina, following acclimation to increased salinity. | the salt-secreting rectal gland plays a major role in elasmobranch osmoregulation, facilitating ion balance in hyperosmotic environments in a manner analogous to the teleost gill. several studies have examined the central role of the sodium pump na(+)/k(+)-atpase in osmoregulatory tissues of euryhaline elasmobranch species, including regulation of na(+)/k(+)-atpase activity and abundance in response to salinity acclimation. however, while the transcriptional regulation of na(+)/k(+)-atpase in th ... | 2015 | 26044040 |
| hypoxia effects on gill surface area and blood oxygen-carrying capacity of the atlantic stingray, dasyatis sabina. | atlantic stingrays, dasyatis sabina, are common residents of shallow-water seagrass habitats that experience natural cycles of severe hypoxia during summer months. we hypothesized that stingrays exposed to hypoxic episodes would improve their hypoxia tolerance by increasing branchial surface area and altering blood oxygen-carrying capacity. to this end, we compared critical oxygen minimum, gill morphology, and hemoglobin/hematocrit levels in a control group of atlantic stingrays held at continuo ... | 2014 | 24352883 |
| differences in activity level between cownose rays (rhinoptera bonasus) and atlantic stingrays (dasyatis sabina) are related to differences in heart mass, hemoglobin concentration, and gill surface area. | aquatic animals are faced with the challenge of extracting oxygen from water, a medium that is metabolically expensive to ventilate and that contains just a fraction of the oxygen concentration relative to air, yet the physiologies of fishes have evolved to support a wide range of activity levels in nature. oxygen delivery components, including gill surface area (oxygen uptake), blood chemistry (oxygen transport), and the heart (system pump), have been positively correlated to activity level in ... | 2012 | 22395532 |
| effect of rapid temperature change on resting routine metabolic rates of two benthic elasmobranchs. | in this study, flow-through respirometry was used to test the effect of acute temperature change on resting routine metabolic rates of two benthic elasmobranchs, atlantic stingrays, dasyatis sabina (n = 7) and whitespotted bamboo sharks, chiloscyllium plagiosum (n = 7) kept under fluctuating temperature regime of 24-27 and 23-25°c, respectively. atlantic stingrays and whitespotted bamboo sharks showed a temperature sensitivity (q(10)) of 2.10 (21-31°c) and 2.08 (20-28°c), respectively. not surpr ... | 2011 | 21553062 |
| is post-feeding thermotaxis advantageous in elasmobranch fishes? | the effects of post-feeding thermotaxis on ileum evacuation and absorption rates were examined in the laboratory using two elasmobranch species, the atlantic stingray dasyatis sabina, which inhabits thermally variable environments, and the whitespotted bamboo shark chiloscyllium plagiosum, a stenothermic fish living on indo-pacific reefs. experiments at temperatures similar to those experienced in nature revealed temperature change had no significant effect on c. plagiosum absorption or evacuati ... | 2011 | 21235555 |
| molecular classification of an elasmobranch angiotensin receptor: quantification of angiotensin receptor and natriuretic peptide receptor mrnas in saltwater and freshwater populations of the atlantic stingray. | among the most conserved osmoregulatory hormone systems in vertebrates are the renin-angiotensin system (ras) and the natriuretic peptides (nps). we examined the ras and np system in the euryhaline atlantic stingray, dasyatis sabina (lesueur). to determine the relative sensitivity of target organs to these hormonal systems, we isolated cdna sequences encoding the d. sabina angiotensin receptor (at) and natriuretic peptide type-b receptor (npr-b). we then determined the tissue-specific expression ... | 2010 | 20869458 |
| comparative punting kinematics and pelvic fin musculature of benthic batoids. | although the majority of batoid elasmobranchs, skates and rays, are benthically associated, benthic locomotion has been largely overlooked in this group. only skates have been previously described to perform a form of benthic locomotion termed "punting." while keeping the rest of the body motionless, the skate's pelvic fins are planted into the substrate and then retracted caudally, which thrusts the body forward. in this study, we demonstrate that this form of locomotion is not confined to the ... | 2010 | 20623523 |
| adaptation of a corticosterone elisa to demonstrate sequence-specific effects of angiotensin ii peptides and c-type natriuretic peptide on 1alpha-hydroxycorticosterone synthesis and steroidogenic mrnas in the elasmobranch interrenal gland. | it is thought that a single corticosteroid, 1alpha-hydroxycorticosterone (1alpha-b), is both a glucocorticoid and mineralocorticoid in the elasmobranch fishes. we investigated the putative mineralocorticoid role of 1alpha-b by examining regulation of interrenal 1alpha-b synthesis by osmoregulatory hormones in the euryhaline stingray dasyatis sabina. using synthesized steroid, a commercial enzyme-linked immunoassay was validated for the quantification of 1alpha-b. in interrenal cultures, the anti ... | 2010 | 20236617 |
| electroreception in the euryhaline stingray, dasyatis sabina. | this study quantified the electrosensitivity of a euryhaline elasmobranch, the atlantic stingray (dasyatis sabina) across a range of salinities. specimens from a permanent freshwater (fw) population in the st johns river system, fl, usa, were compared with stingrays from the tidally dynamic indian river lagoon in east florida, usa. behavioral responses of stingrays to prey-simulating electric stimuli were quantified in fw (0 p.p.t., rho=2026 omega cm), brackish (15 p.p.t., rho=41 omega cm) and f ... | 2009 | 19411548 |
| blood flukes (digenea: aporocotylidae) of stingrays (myliobatiformes: dasyatidae): orchispirium heterovitellatum from himantura imbricata in the bay of bengal and a new genus and species of aporocotylidae from dasyatis sabina in the northern gulf of mexico. | we redescribe orchispirium heterovitellatum based on the holotype and 3 original voucher specimens collected from the mesenteric blood vessels of scaly whiprays himantura imbricata (bloch and schneider, 1801) (as dasyatis imbricatus) captured in the western bay of bengal off waltair, india. we emend the diagnosis of orchispirium to include anterior sucker present, testis looping, cirrus sac enveloping large internal seminal vesicle, oviducal seminal receptacle present, and metraterm short and th ... | 2008 | 18576823 |
| parvalbumin characterization from the euryhaline stingray dasyatis sabina. | the atlantic stingray, dasyatis sabina found along the gulf of mexico and southeastern atlantic coasts, is a euryhaline species of elasmobranch. this species is able to osmotically compensate for changing environmental salinity by altering plasma and intracellular solutes, including urea and counteracting methylamines (betaine and tmao). parvalbumin (pv) is an intracellular protein that facilitates muscle relaxation by sequestering calcium. determining the effects that in situ concentrations of ... | 2008 | 18508399 |
| visual fields of four batoid fishes: a comparative study. | the visual fields of elasmobranch fishes are not well characterized even though this is a fundamental element of the visual system. the batoid fishes (skates, rays) form a monophyletic clade within the subclass elasmobranchii and exhibit a broad range of morphologies and corresponding ecologies. we hypothesized that their visual field characteristics would reflect their diverse morphology and ecology. this was tested by quantifying the monocular, binocular and cyclopean horizontal and vertical v ... | 2008 | 18245624 |
| sex, seasonal, and stress-related variations in elasmobranch corticosterone concentrations. | serum corticosterone was previously studied in numerous elasmobranch fishes (sharks, skates and rays), but the role of this steroid, widespread throughout many taxa, has yet to be defined. the goal of this study was to test whether corticosterone varied in response to acute and chronic capture stress, and across the reproductive cycle in the bonnethead shark, sphyrna tiburo, and atlantic stingray, dasyatis sabina. serum corticosterone in s. tiburo increased following capture and again 24 h post- ... | 2007 | 17977765 |
| the putative mechanism of na(+) absorption in euryhaline elasmobranchs exists in the gills of a stenohaline marine elasmobranch, squalus acanthias. | we recently cloned an nhe3 orthologue from the gills of the euryhaline atlantic stingray (dasyatis sabina), and generated a stingray nhe3 antibody to unequivocally localize the exchanger to the apical side of epithelial cells that are rich with na(+)/k(+)-atpase (a mrc). we also demonstrated an increase in nhe3 expression when stingrays are in fresh water, suggesting that nhe3 is responsible for active na(+) absorption. however, the vast majority of elasmobranchs are only found in marine environ ... | 2007 | 17208025 |
| a new species of thaumatocotyle (monogenea: monocotylidae) from dasyatis sabina (myliobatiformes: dasyatidae) off the coast of south carolina. | thaumatocotyle roumillati n. sp. is described from specimens collected in the nasal fossae of the atlantic stingray, dasyatis sabina (lesueur) from the southeastern coast of the united states, off south carolina. thaumatocotyle roumillati is distinguished from congeners by the size and shape of its penis as well as the presence of a spinelike accessory piece associated with the penis. | 2005 | 17089745 |
| cloning and functional characterization of a second urea transporter from the kidney of the atlantic stingray, dasyatis sabina. | the cloning of cdnas encoding facilitated urea transporters (uts) from the kidneys of the elasmobranchs indicates that in these fish renal urea reabsorption occurs, at least in part, by passive processes. the previously described elasmobranch urea transporter clones from shark (shut) and stingray (strut-1) differ from each other primarily because of the cooh-terminus of the predicted strut-1 translation product being extended by 51-amino acid residues compared with shut. previously, we noted mul ... | 2006 | 16614049 |
| the accumulation of methylamine counteracting solutes in elasmobranchs with differing levels of urea: a comparison of marine and freshwater species. | we compared levels of the major organic osmolytes in the muscle of elasmobranchs, including the methylamines trimethylamine oxide (tmao), betaine and sarcosine as well as the beta-amino acids taurine and beta-alanine, and the activities of enzymes of methylamine synthesis (betaine and tmao) in species with a wide range of urea contents. four marine, a euryhaline in freshwater (dasyatis sabina), and two freshwater species, one that accumulates urea (himantura signifer) and one that does not (pota ... | 2006 | 16481575 |
| organochlorine concentrations, reproductive physiology, and immune function in unique populations of freshwater atlantic stingrays (dasyatis sabina) from florida's st. johns river. | within the past decade, reproductive and health disorders have been reported to occur in unique populations of atlantic stingrays (dasyatis sabina) inhabiting certain components of florida's st. johns river. since these irregularities are consistent with the alleged effects of organochlorine (oc) contaminant exposure in other florida wildlife, the goal of this study was to examine possible associations between oc concentrations and reproduction and/or immune function in stingrays from this river ... | 2006 | 16289699 |
| morphological changes in the clasper gland of the atlantic stingray, dasyatis sabina, associated with the seasonal reproductive cycle. | the clasper gland of the atlantic stingray, dasyatis sabina, was examined over a 1-year period, covering an entire reproductive cycle. changes in clasper gland tissue architecture, fluid production, and cell proliferation were assessed. no changes in tissue architecture were observed. evidence of cell proliferation in the gland epithelium was not detected using immunocytochemistry for proliferating cell nuclear antigen, a cellular marker of mitosis. epithelial cells were not observed to undergo ... | 2006 | 16270309 |
| a putative h+-k+-atpase in the atlantic stingray, dasyatis sabina: primary sequence and expression in gills. | in mammals, the gastric h(+)-k(+)-atpase (hkalpha1) mediates acid secretion in the stomach and kidneys. like mammals, elasmobranchs also secrete acid from their stomachs, but unlike mammals they primarily use their gills for systemic acid excretion instead of their kidneys. the purpose of this study was to determine if an hkalpha1 orthologue exists in an elasmobranch (atlantic stingray, dasyatis sabina), to determine if it is expressed in gills and, if so, to localize its expression and determin ... | 2004 | 15217793 |
| compensation for hypercapnia by a euryhaline elasmobranch: effect of salinity and roles of gills and kidneys in fresh water. | specimens of the euryhaline elasmobranch, dasyatis sabina were acclimated to seawater and fresh water, and exposed to normocapnic (air) and hypercapnic (1% co2 in air) environmental water. blood ph, pco2, and [hco3-], as well as whole-animal net-acid excretion, were measured for up to 24 h of hypercapnia. in a separate experimental series, urine was collected from freshwater acclimated stingrays during 8 h of normocapnia and hypercapnia. stingrays in both salinities at least partially compensate ... | 2003 | 12911113 |
| molecular and functional characterization of a urea transporter from the kidney of the atlantic stingray. | in general, marine elasmobranch fishes (sharks, skates, and rays) maintain body fluid osmolality above seawater, principally by retaining large amounts of urea. maintenance of the high urea concentration is due in large part to efficient renal urea reabsorption. regulation of renal urea reabsorption also appears to play a role in maintenance of fluid homeostasis of elasmobranchs that move between habitats of different salinities. we identified and cloned a novel 2.7-kb cdna from the kidney of th ... | 2003 | 12388386 |
| ontogenetic changes in the response properties of the peripheral electrosensory system in the atlantic stingray (dasyatis sabina). | adult stingrays use their ampullary electroreceptors to detect prey and locate mates, but the response properties and function of their electrosensory system in the pre-adult stages are unknown. we examined the response properties of atlantic stingray (dasyatis sabina) electrosensory primary afferent neurons through ontogeny to determine whether encoding of electrosensory information changes with age, and how it relates to the ontogenetic encoding of biologically relevant electric stimuli. we sh ... | 2002 | 12119532 |
| immunochemical analysis of the vacuolar proton-atpase b-subunit in the gills of a euryhaline stingray (dasyatis sabina): effects of salinity and relation to na(+)/k(+)-atpase. | in the gills of freshwater teleost fishes, vacuolar proton-atpase (v-h(+)-atpase) is found on the apical membrane of pavement and chloride (na(+)/k(+)-atpase-rich) cells, and is an important transporter for energizing na(+) uptake and h(+) excretion. in the gills of elasmobranch fishes, the v-h(+)-atpase has not been extensively studied and its expression in freshwater individuals has not been examined. the goals of this study were to examine the effects of environmental salinity on the expressi ... | 2001 | 11606599 |
| contractile properties of the elasmobranch rectal gland. | the importance of the rectal gland in elasmobranch osmoregulation is well established. the rate of secretion by the gland is under the control of a variety of secretagogues and inhibitors. early morphological work suggested that a band of smooth muscle cells surrounds the periphery of the shark rectal gland between the secretory tubules and the connective tissue capsule. to confirm the presence of the muscle ring, we examined histological sections from two species of shark, squalus acanthias and ... | 2001 | 11104711 |
| characterization of gonadal and extra-gonadal forms of the cdna encoding the atlantic stingray (dasyatis sabina) cytochrome p450 aromatase (cyp19). | cytochrome p450 aromatase (p450arom; cyp19) mediates the conversion of androgens to estrogens and its activity has been found in all vertebrates studied to date. this study describes the full-length cdna encoding the ovarian form of p450arom and the differences in the 5'-untranslated region (5'-utr) of the extra-gonadal p450arom transcript expressed by the atlantic stingray (dasyatis sabina). elasmobranchs (cartilaginous fishes such as sharks, rays and skates) diverged from the other vertebrates ... | 2000 | 11026568 |
| effects of environmental salinity on na(+)/k(+)-atpase in the gills and rectal gland of a euryhaline elasmobranch (dasyatis sabina). | changes in na(+)/k(+)-atpase activity and abundance associated with environmental salinity were investigated in the gills and rectal gland of the atlantic stingray dasyatis sabina. using a ouabain-specific atpase assay and western blotting, we found that stingrays from fresh water had the highest activity and highest relative abundance of na(+)/k(+)-atpase in the gills. using immunohistochemistry, we also found that gills from freshwater stingrays had the greatest number of na(+)/k(+)-atpase-ric ... | 2000 | 10976032 |
| annual cycles of steroid hormone production, gonad development, and reproductive behavior in the atlantic stingray. | the mating season of the atlantic stingray (dasyatis sabina), which begins in august and continues through april, is the longest documented for any elasmobranch fish. despite this protracted mating period, female stingrays ovulate synchronously at the end of the mating season and there is no evidence for sperm storage by females. thus, the proximate causal factors and ultimate function of this extended preovulatory mating are unknown. annual cycles of the gonadal steroids testosterone (t), dihyd ... | 2000 | 10890563 |
| structure of the thyroid gland, serum thyroid hormones, and the reproductive cycle of the atlantic stingray, dasyatis sabina. | this study examines the role of the thyroid gland in the control of reproduction in the viviparous atlantic stingray, dasyatis sabina. thyroid activity in individuals in different reproductive stages was assessed both by microscopic examination of the gland, and by analysis of circulating levels of thyroid hormones from the same individuals. the thyroid gland is a cylindric organ, embedded in a connective tissue capsule, and composed of follicles, i.e., monolayer spheres of thyroid epithelial ce ... | 1999 | 10469988 |
| morphology and epithelial ion transport of the alkaline gland in the atlantic stingray (dasyatis sabina). | the alkaline glands are two fluid-filled sacs that lie on the ventral, posterior surface of each kidney in skates and rays. in this study, the morphology, transepithelial ion transport, fluid constituents, and histochemistry of the alkaline glands of the atlantic stingray, dasyatis sabina, were investigated. the duct from each gland joined the corresponding vas deferens and the resulting two common ducts emptied into the cloaca. dark burgundy, aqueous fluid (ph 8.0-8.2) was secreted into the sac ... | 1999 | 28296501 |
| osmoregulation of the atlantic stingray (dasyatis sabina) from the freshwater lake jesup of the st. johns river, florida. | the goals of this study were to (1) measure plasma osmolytes and rectal gland weights of a freshwater (fw) atlantic stingray (dasyatis sabina) population in the st. johns river, florida, and (2) determine how these parameters change after acclimation to seawater (sw). we hypothesized that the fw d. sabina may show physiological divergence from marine d. sabina, because the fw individuals reproduce and complete their life cycle in the st. johns river. the fw d. sabina hyperregulate their plasma o ... | 2013 | 9754532 |
| increase in gonadotropin-releasing hormone (gnrh) levels in csf after stimulation of the nervus terminalis in atlantic stingray, dasyatis sabina. | the nervus terminalis (nt) contains many cells immunoreactive to gonadotropin-releasing hormone (gnrh). the potential of the nt to release gnrh in vivo was investigated by stimulating the peripheral nerve trunk of atlantic stingrays and collecting cerebrospinal fluid (csf). the csf samples from stimulated animals averaged about twice the levels of mgnrh-like peptide as those of unstimulated animals. these results demonstrate that nervus terminalis activity can effect in vivo gnrh levels in the b ... | 1998 | 9739116 |
| serum concentrations of steroid hormones during reproduction in the atlantic stingray, dasyatis sabina. | the atlantic stingray, dasyatis sabina, has a well-defined annual reproductive cycle in florida. we collected adult specimens over 12 months and evaluated reproductive parameters and serum levels of five steroid hormones, 17beta-estradiol (e2), progesterone (p4), testosterone (t), dihydrotestosterone (dht), and corticosterone (cs). female e2 peaked twice, once in mid-march to early april in association with ovulation and again in mid-june to mid-july in association with the enlargement of a seco ... | 1997 | 9378275 |
| identification of a glycosylated relaxin-like molecule from the male atlantic stingray, dasyatis sabina. | the alkaline gland fluid of the atlantic stingray (dasyatis sabina) contains a molecule that cross-reacts weakly to anti-porcine relaxin antibodies. this material was isolated and purified to homogeneity by reversed-phase high-performance liquid chromatography. in sds gel electrophoresis, the molecule showed an apparent molecular mass of 13 kda which upon reduction formed two polypeptide chains of 4 and 9 kda, respectively. sequence analyses revealed a 27-amino acid residue a chain and a 54-amin ... | 1997 | 9271504 |
| seasonal dynamics of dental sexual dimorphism in the atlantic stingray dasyatis sabina | cartilaginous fishes continuously replace their teeth throughout their life (polyphyodonty) and often show a sexually dimorphic dentition that was previously thought to be an invariant sex character. radial vector analysis of tooth shape in the polyphyodontic stingray dasyatis sabina across a consecutive 24 month period shows a stable molariform morphology for females but a periodic shift in male dentition from a female-like molariform to a recurved cuspidate form during the reproductive season. ... | 1996 | 9320215 |
| variations in cerebellar morphology of the atlantic stingray, dasyatis sabina. | the cerebellar corpus of the atlantic stingray consists of an anterior lobe which is divided into rostral and caudal lobules, and a posterior lobe. the long axis of the posterior lobe and rostral lobule of the anterior lobe both lie along the midline, whereas the orientation of the caudal lobule varies. we examined this variation in 127 animals. in 52% the long axis of the caudal lobule lay on the right of the midline, in 21% it was on the left, and in 27% across the midline. while this distribu ... | 1992 | 1625795 |
| identification of the midbrain locomotor region and its relation to descending locomotor pathways in the atlantic stingray, dasyatis sabina. | the midbrain locomotor region (mlr) in the atlantic stingray, dasyatis sabina, was identified and characterized. stimulation (50-100 microa, 60 hz) of the midbrain in decerebrated, paralyzed animals was used to elicit locomotion monitored as alternating activity in nerves innervating an antagonist pair of elevator and depressor muscles. effective sites for evoking locomotion in the midbrain included parts of several nuclei: the caudal portion of the interstitial nucleus of the medial longitudina ... | 1991 | 1747771 |
| locomotion evoked by stimulation of the brain stem in the atlantic stingray, dasyatis sabina. | the primary pathway descending to the spinal cord to initiate locomotion in the stingray is located in the intermediate to ventral portion of the lateral funiculus; a second pathway is located in the dorsolateral funiculus. the goal of this study was to identify the origins of these pathways in the rhombencephalic reticular formation (rf). to do this we used microstimulation of the rf in conjunction with selective lesions of the brain stem and spinal cord. in some animals microinjections of exci ... | 1990 | 2299392 |
| glutamine synthetase isozymes in elasmobranch brain and liver tissues. | glutamine synthetase is present as isozymic forms in the elasmobranchs squalus acanthias (dogfish shark) and dasyatis sabina (stingray). subcellular fractionation of elasmobranch brain and liver tissue shows the enzyme to be predominantly cytosolic in the former tissue and mitochondrial in the latter. for the cytosolic brain enzyme, the subunit mr equals 42,000 in the stingray and 45,000 in the shark, as determined by sodium dodecyl sulfate-gel electrophoresis/western blotting. the subunit mr = ... | 1987 | 2878924 |
| intracellular recording from pectoral fin motoneurons of the stingray dasyatis sabina, an elasmobranch fish. | intracellular recordings were made from antidromically identified pectoral fin motoneurons in unanesthetized, decerebrate stingrays (dasyatis sabina). these recordings had the three all-or-none components seen in other vertebrate motoneuron recordings. about 25% of the impalements had resting membrane potentials that were greater than -80 mv, which is larger than those of motoneurons from other vertebrate species. a novel depolarizing afterpotential (dap) is associated with the isolated action p ... | 1984 | 6716118 |
| the distribution of serotonin in the cns of an elasmobranch fish: immunocytochemical and biochemical studies in the atlantic stingray, dasyatis sabina. | the distribution of serotonin (5ht) in the brain of the atlantic stingray was studied with peroxidase-antiperoxidase immunocytochemistry and high-pressure liquid chromatography. the regional concentrations of 5ht determined for this stingray fell within the range of values previously reported for fishes. a consistent trend in vertebrates for the hypothalamus and midbrain to have the highest concentrations and the cerebellum the lowest was confirmed in stingrays. neuronal cell bodies and processe ... | 1983 | 6363469 |
| immunocytochemical demonstration of serotonergic neurons and processes in the retina and optic nerve of the stingray, dasyatis sabina. | neurons and processes in the stingray retina can be stained using pap immunohistochemistry and an antibody to serotonin, without pharmacological pretreatment. most of the cell bodies are in the inner nuclear layer while the processes ramify in the inner plexiform layer suggesting the presence of a population of serotonin containing amacrine cells in this species. scattered immunopositive axons were observed in the optic nerve from the optic chiasm to the optic nerve head. | 1983 | 6347336 |
| immunohistochemical studies on the distribution and origin of candidate peptidergic primary afferent neurotransmitters in the spinal cord of an elasmobranch fish, the atlantic stingray (dasyatis sabina). | the distribution and origin of four peptide neurotransmitter candidates of primary afferents (substance p, sp; somatostatin, ss; cholecystokinin, cck; and vasoactive intestinal polypeptide, vip) were studied in the stingray with peroxidase-antiperoxidase (pap) immunohistochemistry. this elasmobranch has virtually no unmyelinated primary afferents, having instead only large and small myelinated afferents. sp-like immunoreactivity was distributed densely in the superficial aspect of the substantia ... | 1983 | 6187783 |
| immunocytochemical demonstration of serotonergic cells, terminals and axons in the spinal cord of the stingray, dasyatis sabina. | serotonin-like immunoreactivity, as demonstrated by the pap method, was contained within cells as well as fibers and terminals, in the spinal cord of the stingray. serotonergic spinal neurons were seen on 43% of the sections examined and were restricted to the ventral white matter. immunoreactive terminals and varicosities were densely distributed over the spinal gray matter at all segmental levels, and stained fibers were seen in all portions of the white matter with the exception of the medial ... | 1982 | 7049319 |
| freeze-fracture and morphometric analysis of occluding junctions in rectal glands of elasmobranch fish. | the structure of occluding junctions in secretory and ductal epithelium of salt-secreting rectal glands from two species of elasmobranch fish, the spiny dogfish squalus acanthias and the stingray dasyatis sabina, was examined by thin-section and freeze-fracture electron microscopy. in both species, occluding junctions between secretory cells are shallow in their apical to basal extent and are characterized by closely juxtaposed parallel strands. average strand number in the dogfish was 3.5 +/- 0 ... | 1981 | 6260950 |
| the organization of the extraocular motor nuclei in the atlantic stingray, dasyatis sabina. | retrograde transport of hrp was used to determine the location and organization of the motor nuclei innervating the extrinsic eye muscles of the stingray, an elasmobranch fish. oculomotor neurons are located both medial to and immediately ventrolateral to the mlf in the rostral midbrain. a ventral oculomotor nucleus was found among the iiird nerve rootlets close to the base of the midbrain. the dendrites of cells in the dorsal nucleus appear to be preferentially oriented in the transverse plane ... | 1980 | 7440785 |
| a documentation of an age related increase in neuronal and axonal numbers in the stingray, dasyatis sabina, leseuer. | | 1978 | 8980715 |
| primary afferent depolarization and inhibory interactions in spinal cord of the stingray, dasyatis sabina. | 1. excitability changes in primary afferents and inhibitory interactions in evoked spinal cord activity were investigated in unanesthetized stingrays (dasyatis subina) with high cervical spinal transections. 2. primary afferent excitability increases following a conditioning stimulus to an adjacent segmental nerve were demonstrated with the wall (31) technique. 3. stimulation of a-alpha,beta and a-delta afferent fibers produced excitability increases in both a-alpha,beta and delta-fibers of the ... | 1978 | 621539 |
| central effects of volleys in sensory and motor components of peripheral nerve in the stingray, dasyatis sabina. | | 1978 | 621538 |
| the hemoglobin of the common sting-ray, dasyatis sabina: structural and functional properties. | 1. the hemoglobin of the sting-ray, dasyatis sabina, is both polymorphic and heterogeneous; three components predominate. 2. one major component has two kinds of polypeptide chain, of which one, presumably an alpha-chain, has a blocked nh2-terminus and an arginyl cooh-terminus, whereas carboxypeptidases a and b release tyrosine and histidine from the cooh-terminus of the beta-chain. 3. the amino acid sequence of the beginning nh2-terminal segment of the beta-chain of the major component has been ... | 1978 | 318333 |
| pituitary, adrenal and thyroid influences on osmoregulation in the euryhaline elasmobranch, dasyatis sabina. | | 1975 | 241550 |
| the stimulation of corticosteroidogenesis in the interrenal of the elasmobranch dasyatis sabina by mammalian acth. | | 1975 | 240540 |
| the control of the interrenal by the pituitary in the elasmobranch, dasyatis sabina. | | 1973 | 4146113 |
| rectal gland secretion in the stingray, dasyatis sabina. | | 1972 | 4402717 |
| regulation of the ventilation-perfusion ratio in the gills of dasyatis sabina and squalus suckleyi. | | 1971 | 4150232 |