| a neurobehavioral model for rapid actions of corticosterone on sensorimotor integration. | stress-induced corticosterone (cort) secretion that causes a rapid blockade of courtship clasping by male roughskin newts (taricha granulosa) is mediated by a specific neuronal membrane receptor for cort. amplectic clasping, which can be triggered by pressure on the ventral body surface and cloaca, is controlled by the influence of medullary neurons on the spinal cord. using clasping as a simple neurobehavioral model, we have focused our analysis of cort effects on clasping by examining the ster ... | 1999 | 10323677 |
| potential for local adaptation in response to an anthropogenic agent of selection: effects of road deicing salts on amphibian embryonic survival and development. | the application of millions of tons of road deicing salts every winter in north america presents significant survival challenges to amphibians inhabiting roadside habitats. while much is known of the effects of nacl on anuran tadpoles, less is known of effects on amphibian eggs, or any caudate life stage. in addition, little is known of the effects of mgcl2, which is now the 2nd most commonly used road deicer. most studies have considered amphibians to be helpless victims of deicing salts, and i ... | 2012 | 23467723 |
| rapid, corticosterone-induced disruption of medullary sensorimotor integration related to suppression of amplectic clasping in behaving roughskin newts (taricha granulosa). | endogenously secreted or injected corticosterone (cort) rapidly suppresses courtship clasping in male roughskin newts (taricha granulosa) by an action on a specific neuronal membrane receptor. previous studies, using immobilized newts, showed that cort administration rapidly depresses excitability of reticulospinal neurons and attenuates medullary neuronal responsiveness to clasp-triggering sensory stimuli. the present study used freely moving newts to examine clasping responses and concurrently ... | 1998 | 9878276 |
| corticotropin-releasing factor enhances locomotion and medullary neuronal firing in an amphibian. | corticotropin-releasing factor (crf) administration has been shown to act centrally to enhance locomotion in rats and amphibians. in the present study we used an amphibian, the roughskin newt (taricha granulosa), to characterize changes in medullary neuronal activity associated with crf-induced walking and swimming in animals chronically implanted with fine-wire microelectrodes. neuronal activity was recorded from the raphe and adjacent reticular region of the rostral medulla. under baseline con ... | 1996 | 8724179 |
| three rarely reported digeneans inhabiting amphibians from vancouver island, british columbia, canada. | three rarely reported species of digeneans were collected in amphibian hosts from diversion reservoir, sooke, vancouver island, british columbia, canada. the endangered anuran rana aurora hosted glypthelmins californiensis, gorgoderina multilobata, and megalodiscus microphagus. in addition, the anuran pseudacris regilla and the caudatan taricha granulosa hosted megalodiscus microphagus. gorgoderina multilobata has been reported only once since 1936 and has never been reported outside of californ ... | 2005 | 16419782 |
| antibodies against different forms of gnrh distinguish different populations of cells and axonal pathways in a urodele amphibian, taricha granulosa. | neurons immunoreactive to the peptide hormone gonadotropin-releasing hormone (gnrh) have been identified in the posterior diencephalon or anterior midbrain of diverse vertebrates. these cells are located caudal to the more well-characterized gnrh neurons in the nervus terminalis and septo-preoptic area, and are believed to express one or more of the nonmammalian forms of the gnrh. the present study utilized immunocytochemical techniques to determine whether the posterior gnrh group is present in ... | 1994 | 8089274 |
| gonadotropin-releasing hormones in microdissected brain regions of an amphibian: concentration and anatomical distribution of immunoreactive mammalian gnrh and chicken gnrh ii. | mammalian and chicken ii gonadotropin-releasing hormones (mgnrh, cgnrh ii) were extracted from 350 microns diameter punches from brains of a urodele amphibian, taricha granulosa, and measured by means of radioimmunoassay (ria) with specific antisera. measurable quantities of both peptides were found in the lateral pallium, the subpallium (along the course of the nervus terminalis), the preoptic area, habenula, optic tectum, infundibulum, paraventricular organ/posterior tubercle of the caudal die ... | 1994 | 7716272 |
| two hemoglobin-binding proteins identified in the plasma of the amphibian taricha granulosa. | the plasma of the amphibian newt taricha granulosa has been shown to be devoid of haptoglobin. upon hemolysis, taricha albumin and another protein associate with hemoglobin. the acute-phase response to inflammation observed in birds and mammals appears to be absent in taricha. taricha hemoglobin failed to bind to human haptoglobin. taricha hemoglobin not only failed to dissociate into alpha beta dimers as did human hb, but formed alpha beta octamers. | 1984 | 6697692 |
| sensitivity and specificity of salamandrid integumental transepithelial potential to prolactin. | the effects of ovine prolactin (oprl), bovine growth hormone (bgh) and human placental lactogen (hpl) on in vivo integumental transepithelial potential (tep) were examined in two salamandrid urodeles, adult terrestrial-phase taricha granulosa and the juvenile red-eft stage of notophthalmus viridescens. tep in efts treated with 1.0 microgram oprl/2 days fell from 73.3 +/- 6.1 to 15.2 +/- 5.5 mv by day 7 (p less than 0.001), whereas the tep of efts treated with either 1.0 or 10 micrograms bgh/2 da ... | 1985 | 4018555 |
| bisalbuminemia in an amphibian. | improved electrophoretic resolution revealed two albumin-like proteins in taricha granulosa plasma (bisalbuminemia). the taricha proteins were compared to mammalian, avian and reptilian serum albumins regarding molecular weight, amino acid composition, isoelectric character, solubility and the binding of hemin and dyes. the results indicate that although the two taricha proteins have demonstrated hemoglobin-binding ability, they possess traits that characterize them to be true serum albumins. | 1985 | 4017540 |
| uptake of iron from hemoglobin and the haptoglobin-hemoglobin complex by hemolytic bacteria. | the abilities of staphylococcus aureus and streptococcus pyogenes to remove iron from mouse 59fe hemoglobin that was either in free form or complexed with human haptoglobin, were evaluated. 59fe hemoglobin from the amphibian taricha granulosa was also used in free form or complexed with the amphibian's hemoglobin-binding proteins. contrary to what was reported from a study using pathogenic escherichia coli, haptoglobin failed to exhibit a bacteriostatic influence when complexed with hemoglobin. ... | 1985 | 3902529 |
| seasonal changes in luteinizing hormone-releasing hormone concentrations in microdissected brain regions of male rough-skinned newts (taricha granulosa). | luteinizing hormone-releasing hormone (lhrh) concentrations were measured in specific brain areas of male rough-skinned newts collected from a single population throughout the reproductive cycle. plasma androgen and corticosterone (b) concentrations were also measured. androgen concentrations were highest during the breeding season (winter) and lowest during the summer. in contrast, plasma b was lowest during the breeding season and highest in the summer. concentrations of lhrh in the infundibul ... | 1985 | 3888777 |
| autoradiographic characterization of binding sites labelled with vasopressin in the brain of a urodele amphibian. | because arginine vasotocin (avt) activates male sexual behaviors in the rough-skinned newt (taricha granulosa), quantitative autoradiography with radiolabelled arginine vasopressin (3h-avp) was used to characterize putative avt receptors in the telencephalon of this amphibian. analyses were restricted to specific binding sites in the medial pallium, although dense binding also was observed in the dorsal pallium and amygdala pars lateralis. binding of 3h-avp to these sites was saturable, specific ... | 1988 | 3173642 |
| thyroid function in adult rough-skinned newts (taricha granulosa): effects of hypophysectomy and hormone replacement. | this study examines the regulation of thyroid activity in adult rough-skinned newts, taricha granulosa. aquatic, breeding-condition newts were hypophysectomized and were injected for 23 days with the mammalian adenohypophysial hormones: acth, prl, and gh. during a fourth week of treatment, these newts also received tsh. plasma t4 concentrations were lower in hypophysectomized newts than in sham-hypophysectomized newts 23 days after surgery. both acth and prl increased t4 titers above these in sa ... | 1985 | 2991080 |
| autoradiographic localization of putative arginine vasotocin receptors in the kidney of a urodele amphibian. | the distribution and characteristics of putative arginine vasotocin (avt) receptors in the urodele amphibian kidney were investigated using in vitro quantitative autoradiography. specific binding sites for [3h]arginine vasopressin (avp) in the kidney of the rough-skinned newt (taricha granulosa) were located over the glomeruli. scatchard analysis showed that, in the range of concentrations tested (0.2 to 22 nm), [3h]avp bound to a single class of receptors with a dissociation constant of 1.4 nm ... | 1990 | 2347485 |
| two dispersed highly repeated dna families of triturus vulgaris meridionalis (amphibia, urodela) are widely conserved among salamandridae. | two bamhi families of repeated sequences were characterized from the genome of the italian smooth newt, triturus vulgaris meridionalis (amphibia, urodela). the first family, which is divided into subfamilies, consists of tandemly arranged arrays whose basic repeat is around 398 bp long; these arrays are dispersed throughout the entire chromosome sets of the various species of triturus tested. moreover the family is widely conserved among salamandridae, being detected by genomic dna blotting of n ... | 1991 | 2009819 |
| reactivation of outer-arm-depleted lung axonemes: evidence for functional differences between inner and outer dynein arms in situ. | demembranated axonemes isolated from newt lung ciliated cells show a complex beat frequency response to varying [mgatp] and temperature [hard and cypher, 1992, cell motil. cytoskeleton 21:187-198]. the present study was undertaken to ascertain whether the beat frequency of outer-arm-depleted newt lung axonemes is controlled in a manner similar to that of intact axonemes. populations of demembranated ciliary axonemes were isolated by triton x-100 extraction of lungs from the newt, taricha granulo ... | 1992 | 1533820 |
| alpha-chain sequence of newt haemoglobin (taricha granulosa). | the amino acid sequence of the alpha-chain of the major haemoglobin of a newt, t. granulosa, has been determined. the chain is 142 residues long and has an extra methionine at its n-terminus when compared with human alpha-chain. most of the tryptic peptides were sequenced by a combination of the subtractive edman method and by deduction from the compositions of overlapping fragments produced by various enzymic treatments. the sequence of two 'core' regions was obtained by automatic sequencing of ... | 1977 | 901300 |
| histological analysis of forelimb regeneration in the california newt taricha granulosa. | the regenerative ability of the forelimbs of the california rough-skinned newt, taricha granulosa was determined and compared to the same ability of the adult mexican axolotl, ambystoma mexicanum. forelimbs were amputated distally at the wrist and limbs removed at 1, 2, 3, 4, 5 and 6 weeks post-amputation were examined by histological analysis. since vitamin a and its derivatives cause extreme changes in pattern formation in the regenerating amphibian limb, we decided to study the ability of ret ... | 2005 | 1525332 |
| biophysical costs associated with tetrodotoxin resistance in the sodium channel pore of the garter snake, thamnophis sirtalis. | tetrodotoxin (ttx) is a potent toxin that specifically binds to voltage-gated sodium channels (nav). ttx binding physically blocks the flow of sodium ions through nav, thereby preventing action potential generation and propagation. ttx has different binding affinities for different nav isoforms. these differences are imparted by amino acid substitutions in positions within, or proximal to, the ttx-binding site in the channel pore. these substitutions confer ttx-resistance to a variety of species ... | 2011 | 20820785 |
| acute toxic hazard evaluations of glyphosate herbicide on terrestrial vertebrates of the oregon coast range. | the degree to which dose responses of model organisms (lab rodents) can adequately predict dose responses of free-ranging wild mammals or amphibians is unknown, and the relative sensitivity of such species to body loading of a toxicant such as glyphosate is seldom reported. for relative effects of dosage, we compare sensitivity of nine wild vertebrate species to effects of high doses of glyphosate in swiss-webster laboratory mice both by gavage and by intraperitoneal injection. we also evaluate ... | 2008 | 18504846 |
| pheromones enhance somatosensory processing in newt brains through a vasotocin-dependent mechanism. | we tested whether the sex pheromones that stimulate courtship clasping in male roughskin newts do so, at least in part, by amplifying the somatosensory signals that directly trigger the motor pattern associated with clasping and, if so, whether that amplification is dependent on endogenous vasotocin (vt). female olfactory stimuli increased the number of action potentials recorded in the medulla of males in response to tactile stimulation of the cloaca, which triggers the clasp motor reflex, as w ... | 2008 | 18445557 |
| neuroanatomical distribution of cannabinoid receptor gene expression in the brain of the rough-skinned newt, taricha granulosa. | type i cannabinoid receptor (cb1) is a g-protein coupled receptor with a widespread distribution in the central nervous system in mammals. in a urodele amphibian, the rough-skinned newt (taricha granulosa), recent evidence indicates that endogenous cannabinoids (endocannabinoids) mediate behavioral responses to acute stress and electrophysiological responses to corticosterone. to identify possible sites of action for endocannabinoids, in situ hybridization using a gene and species specific crna ... | 2006 | 16415569 |
| cloning, pharmacological characterization and tissue distribution of an orl1 opioid receptor from an amphibian, the rough-skinned newt taricha granulosa. | we have cloned and characterized an opioid receptor-like (orl1; also referred to as nop) receptor from a urodele amphibian, the rough-skinned newt taricha granulosa the cdna clone encodes a protein of 368 amino acids that contains the seven hydrophobic domains characteristic of g-protein-coupled receptors, and has the highest sequence identity to the frog (rana pipiens) nociceptin-like and human orl1 opioid receptors (79.6 and 68.4%, respectively). saturation binding assays on membranes from cos ... | 2005 | 15691892 |
| xenopus laevis cb1 cannabinoid receptor: molecular cloning and mrna distribution in the central nervous system. | in the present research we isolated and characterized xenopus laevis cb1 cannabinoid receptor mrna. the cb1 coding sequence shows a high degree of identity with those of other vertebrates, mammals included, confirming that cb1 receptor is conserved over the course of vertebrate evolution. notably, the similarity between the x. laevis cb1 sequence and that of the urodele amphibian taricha granulosa is not higher than the similarity existing between xenopus and mammals, thus supporting phylogeneti ... | 2003 | 12900919 |
| rapid corticosterone-induced impairment of amplectic clasping occurs in the spinal cord of roughskin newts (taricha granulosa). | courtship clasping, a reproductive behavior in male roughskin newts (taricha granulosa), is rapidly blocked by an action of corticosterone (cort) at a specific neuronal membrane receptor. the cort-induced impairment of clasping in behaving newts appears to be mediated partly by an elimination of clasping-related activity in medullary reticulospinal neurons. previous studies of rapid cort actions in taricha have focused on the brain, so existence of cort action in the spinal cord or peripheral ne ... | 2003 | 12614638 |
| multiple forms of gonadotropin-releasing hormone in amphibian brains. | several forms of gonadotropin-releasing hormone (gnrh)-like molecules were found in brains of both anurans (frogs) and urodeles (salamanders). the presence of the mammalian-like gnrh molecule was confirmed by hplc and cross-reactivity studies. small amounts of salmonid-like gnrh molecules in the brains of frogs (rana pipiens, hyla regilla) and salamanders (taricha granulosa, ambystoma gracile) were detected by comparing the hplc chromatographic pattern and immunological reactivity of the brain e ... | 2012 | 3514371 |
| pigment patterns of larval salamanders (ambystomatidae, salamandridae): the role of the lateral line sensory system and the evolution of pattern-forming mechanisms. | in many species of salamanders, pigment cells derived from the neural crest give rise to a horizontal stripe pattern in hatchling larvae. a defining element of these horizontal stripe patterns is a region over the middle of the myotomes that is relatively free of melanophores. this study shows that formation of a "melanophore-free region" and horizontal stripe pattern in ambystoma tigrinum tigrinum (family ambystomatidae) correlates with the development of the trunk lateral line sensory system. ... | 1996 | 8626032 |
| neurophysiological effects of vasotocin and corticosterone on medullary neurons: implications for hormonal control of amphibian courtship behavior. | research on a wide variety of vertebrates, from fish to mammals, reveals that corticosteroid hormones and vasotocin-like neuropeptides can potently modulate reproductive behaviors. but, it is not clear how the behavioral effects of these chemical messengers relate to functional properties of behavior-controlling neurons. this problem was investigated in the roughskin newt, taricha granulosa, an amphibian in which the administration of arginine vasotocin (avt) facilitates and corticosterone (cort ... | 1995 | 8544954 |
| steroid modulation of gabaa receptors in an amphibian brain. | steroids can modulate gamma-aminobutyric acid (gabaa) receptor function in rat brains, but the physiological relevance of this mechanism is still unclear. to determine whether this phenomenon is widespread among vertebrates, we investigated steroid modulation of gabaa receptors in amphibian brain tissue. equilibrium binding parameters for t-butylbicyclophosphorothionate ([35s]tbps) and [3h]flunitrazepam were similar in taricha granulosa and mammalian brains, as was the allosteric regulation of [ ... | 1994 | 8069672 |
| juvenile amphibians do not avoid potentially lethal levels of urea on soil substrate. | we examined the effects of a forest fertilizer (urea) on newly metamorphosed terrestrial amphibians (western toads, bufo boreas; cascades frogs, rana cascadae; long-toed salamanders, ambystoma macrodactylum; and roughskin newts, taricha granulosa). we examined avoidance behavior of western toads and cascades frogs on both paper towel and soil substrates dosed with urea (control and 100 kg n/ha and an additional treatment of 50 kg n/ha for western toads on soil substrate) and avoidance behavior o ... | 2001 | 11596767 |
| physiological responses to salinity vary with proximity to the ocean in a coastal amphibian. | freshwater organisms are increasingly exposed to elevated salinity in their habitats, presenting physiological challenges to homeostasis. amphibians are particularly vulnerable to osmotic stress and yet are often subject to high salinity in a variety of inland and coastal environments around the world. here, we examine the physiological responses to elevated salinity of rough-skinned newts (taricha granulosa) inhabiting a coastal stream on the pacific coast of north america and compare the physi ... | 2017 | 27327182 |
| female newts (taricha granulosa) produce tetrodotoxin laden eggs after long term captivity. | we investigated the presence of tetrodotoxin (ttx) in the eggs of wild-caught newts (taricha granulosa) at capture and again after one, two, and three years in captivity. females initially produced eggs that contained quantities of ttx similar to previous descriptions of eggs from wild-caught adults. after the first year in captivity, the egg toxicity from each female declined, ultimately remaining constant during each of the successive years in captivity. despite declining, all females continue ... | 2012 | 22867631 |
| comparing the natural and anthropogenic sodium channel blockers tetrodotoxin and indoxacarb in garter snakes. | synthetic chemicals, such as pesticides, are used in a variety of ways in the agricultural industry. anthropogenic chemicals pose a unique challenge to organisms because of the lack of evolutionary history between the chemical and the organism. however, research has shown that some organisms have a resistance to these synthetic chemicals due to their evolved resistance to a natural compound with a similar structure or mode of action. indoxacarb (indox) is a relatively new pesticide with a simila ... | 2016 | 27074769 |
| suppression of sex behavior by kappa opiates and stress steroids occurs via independent neuroendocrine pathways. | endocannabinoids and their receptors are found throughout the brain of all vertebrates. by virtue of their wide distribution, endocannabinoids have the potential to affect many behaviors. prior research has shown that cannabinoids inhibit courtship-clasping and mediate behavioral responses to stress in male rough-skinned newts, taricha granulosa, and cannabinoid signaling is initiated by rapid actions of the steroid corticosterone (cort) at its specific membrane receptor (mcr). this same mcr als ... | 2015 | 25307952 |
| tetrodotoxin concentrations within a clutch and across embryonic development in eggs of the rough-skinned newts (taricha granulosa). | tetrodotoxin is an enigmatic neurotoxin that is found in a wide-variety of organisms. unfortunately, tetrodotoxin (ttx) toxicity across life-history stages is poorly understood in most organisms. rough-skinned newts (taricha granulosa) possess the greatest known quantities of ttx of any organism and numerous studies have begun to elucidate these patterns in this species. we conducted a series of studies to answer the following questions: (1) do eggs from a single female's clutch vary in toxicity ... | 2014 | 25159189 |
| developmental and evolutionary history affect survival in stressful environments. | the world is increasingly impacted by a variety of stressors that have the potential to differentially influence life history stages of organisms. organisms have evolved to cope with some stressors, while with others they have little capacity. it is thus important to understand the effects of both developmental and evolutionary history on survival in stressful environments. we present evidence of the effects of both developmental and evolutionary history on survival of a freshwater vertebrate, t ... | 2014 | 24748021 |
| increased frequency and severity of developmental deformities in rough-skinned newt (taricha granulosa) embryos exposed to road deicing salts (nacl & mgcl2). | road-side aquatic ecosystems in north america are annually polluted with millions of tons of road deicing salts, which threaten the survival of amphibians which live and breed in these habitats. while much is known of the effects of nacl, little is known of the second most-commonly used deicer, mgcl(2), which is now used exclusively in parts of the continent. here we report that environmentally relevant concentrations of both nacl and mgcl(2) cause increased incidence of developmental deformitie ... | 2013 | 23207496 |
| fine-scale selection by ovipositing females increases egg survival. | one of the most important defenses for the eggs of ovipositing female organisms is to avoid being laid in the same habitat as their predators. however, for most organisms, completely avoiding an offspring's predators is not possible. one mechanism that has been largely overlooked is for females to partition an oviposition site into microhabitats that differ in quality for offspring survival. we conducted a series of experiments to examine whether female newts avoid microhabitats utilized by thei ... | 2012 | 23170211 |
| interfamily variation in amphibian early life-history traits: raw material for natural selection? | the embryonic development and time to hatching of eggs can be highly adaptive in some species, and thus under selective pressure. in this study, we examined the underlying interfamily variation in hatching timing and embryonic development in a population of an oviparous amphibian, the rough-skinned newt (taricha granulosa). we found significant, high variability in degree of embryonic development and hatching timing among eggs from different females. patterns of variation were present regardless ... | 2012 | 22957168 |
| predatory caddisfly larvae sequester tetrodotoxin from their prey, eggs of the rough-skinned newt (taricha granulosa). | caddisfly larvae (limnophilus spp.) are important predators of eggs of the rough-skinned newt (taricha granulosa). newts may possess extremely large quantities of the neurotoxin tetrodotoxin (ttx) in their skin, and females may provision this toxin in their eggs. using a competitive inhibition enzymatic immunoassay, we examined ttx-resistant caddisflies, sympatric with the known most toxic population of newts, for the presence of ttx. we found that caddisflies sequester ttx after consuming eggs ... | 2012 | 23160993 |
| behaviroal, pharmacological, and molecular characterization of an amphibian cannabinoid receptor. | investigation of cannabinoid pharmacology in a vertebrate with a phylogenetic history distinct from that of mammals may allow better understanding of the physiological significance of cannabinoid neurochemistry. taricha granulosa, the roughskin newt, was used here to characterize an amphibian cannabinoid receptor. behavioral experiments demonstrated that the cannabinoid agonist levonantradol inhibits both newt spontaneous locomotor activity and courtship clasping behavior. inhibition of clasping ... | 2000 | 10854287 |
| the measurement of sexual selection using bateman's principles: an experimental test in the sex-role-reversed pipefish syngnathus typhle. | angus j. bateman's classic study of sexual selection in drosophila melanogaster has had a major influence on the development of sexual selection theory. in some ways, bateman's study has served a catalytic role by stimulating debate on sex roles, sexual conflict and other topics in sexual selection. however, there is still considerable disagreement regarding whether or not "bateman's principles" are helpful in the study of sexual selection. here, we test the idea that bateman's principles provid ... | 2005 | 21676838 |
| urodeles remove mesoderm from the superficial layer by subduction through a bilateral primitive streak. | urodeles begin gastrulation with much of their presumptive mesoderm in the superficial cell layer, all of which must move into the deep layers during development. we studied the morphogenesis of superficial mesoderm in the urodeles ambystoma maculatum, ambystoma mexicanum, and taricha granulosa. in all three species, somitic, lateral, and ventral mesoderm move into the deep layer during gastrulation, ingressing through a "bilateral primitive streak" just inside the blastopore. the mesodermal epi ... | 2002 | 12167400 |
| hemoglobins of an amphibia, the neotenous ambystoma mexicanum. complete amino-acid sequence of the alpha chain of the major component using automatic solid-phase edman degradation. | the primary structure of axolotl (neotenous ambystoma mexicanum) alpha chain has been determined. nh2-terminal sequence data were performed using the solid-phase method. complete amino acid assignments were deduced from the sequences of peptides obtained after cleavage with cyanogen bromide; the methionine-containing peptides, isolated from alpha chain tryptic digest, allowing the alignment of these fragments. all overlaps have been clearly established. axolotl alpha chain contains 142 residues, ... | 1980 | 7358052 |
| distribution of tetrodotoxin, 6-epitetrodotoxin, and 11-deoxytetrodotoxin in newts. | tetrodotoxin was detected in all nine species of newts tested, 6-epitetrodotoxin in six species, and 11-deoxytetrodotoxin in five species. only one species lacked the analogues, thus suggesting that the analogues were common metabolites among newts. toxin levels were high in taricha granulosa and notophthalmus viridescens followed by cynops spp. distinct differences in toxin contents and profiles existed among species and tissues. | 1990 | 2339439 |
| in vitro fusion of newt macrophages. | spontaneous formation of multinucleate giant cells is often observed in in vitro cultures of peritoneal adherent macrophages from the newts, notophthalmus viridescens and taricha granulosa (urodele amphibians). the frequency of such giant cells in these cultures is increased by the addition of phorbol myristic acetate at the initiation of the cultures. this high frequency of multinucleate cells permitted us to evaluate whether multinucleate giant cells arise by cell fusion and/or by repeated nuc ... | 1988 | 3404109 |
| cell surface changes during dedifferentiation in the metaplastic transformation of iris into lens. | changes at the cell periphery during the dedifferentiative phase of the metaplastic transformation of iris into lens have been studied in notophthalmus viridescens and taricha granulosa using cell electrophoresis. cell surface charge density increases as early as 1-3 days after lens removal. cells of regenerates at 10-15 days after lentectomy have significantly lower electrophoretic mobilities than those of the irises of nonlentectomized newts. decrease in surface charge density is due, at least ... | 1972 | 4653413 |
| sensitivity to urea fertilization in three amphibian species. | forest fertilization with granular urea is a well-established management practice in many forested regions of the world. we hypothesize that chemical forest fertilizers may be affecting forest-dwelling wildlife. in the laboratory, we studied the effects of fertilization doses of granular urea on three species of forest-dwelling amphibians (plethodon vehiculum, rhyacotriton variegatus, and taricha granulosa). in avoidance experiments, the three species avoided a substrate treated with a dose of 2 ... | 2001 | 11443373 |
| secretion and regeneration of tetrodotoxin in the rough-skin newt (taricha granulosa). | rough-skin newts (taricha granulosa) released tetrodotoxin (ttx) in their skin secretions in response to mild electric stimulation. this release resulted in a large (21% to almost 90% of the pre-stimulation levels) reduction in the amount of ttx present in the dorsal skin of individual newts. over the next 9 months newts significantly regenerated the levels of ttx in their skin. these data, in combination with previously published results, are consistent with the hypothesis that these newts prod ... | 2004 | 15530976 |
| sexually dimorphic concentrations of arginine vasotocin in sensory regions of the amphibian brain. | arginine vasotocin (avt) regulates reproductive behaviors in amphibians. we measured avt in the brains of bullfrogs (rana catesbeiana) and newts (taricha granulosa) using radioimmunoassay. in bullfrogs, avt concentrations were greater in males, compared to females, in the amygdala pars lateralis, optic tectum, and tegmentum. concentrations in the dorsolateral nucleus were greater in females. in newts, avt concentrations were also greater in the tectum and tegmentum of males. avt may modulate dim ... | 1992 | 1393583 |
| interacting stressors and the potential for adaptation in a changing world: responses of populations and individuals. | to accurately predict the impact of environmental change, it is necessary to assay effects of key interacting stressors on vulnerable organisms, and the potential resiliency of their populations. yet, for the most part, these critical data are missing. we examined the effects of two common abiotic stressors predicted to interact with climate change, salinity and temperature, on the embryonic survival and development of a model freshwater vertebrate, the rough-skinned newt (taricha granulosa) fro ... | 2017 | 28680662 |
| to stress or not to stress: physiological responses to tetrodotoxin in resistant gartersnakes vary by sex. | the activation of the hypothalamic pituitary adrenal (hpa) axis is one of the most important physiological processes in coping with any deviation in an organism's homeostasis. this activation and the secretion of glucocorticoids, such as corticosterone, allow organisms to cope with perturbations and return to optimal physiological functioning as quickly as possible. in this study, we examined the hpa axis activation in common gartersnakes (thamnophis sirtalis) as a response to a natural toxin, t ... | 2017 | 28380330 |
| detrimental effects of zinc oxide nanoparticles on amphibian life stages. | while the use of nanoparticles has dramatically increased in recent years, the ecological consequences are not well known. in particular, little research has been done to investigate the potentially detrimental effects of nanoparticles on amphibians, especially across all life-history stages of salamanders and newts (caudates). to address this dearth in knowledge, we examined the effects of zinc oxide (zno) nanoparticles on egg, larval, and adult rough-skinned newts (taricha granulosa). chronic ... | 2016 | 27453487 |
| brainstem neuronal and behavioral activation by corticotropin-releasing hormone depend on the behavioral state of the animal. | central administration of corticotropin-releasing hormone (crh) is known to enhance locomotion across a wide range of vertebrates, including the roughskin newt, taricha granulosa. the present study aimed to identify the crh effects on locomotor-controlling medullary neurons that underlie the peptide's behavioral stimulating actions. single neurons were recorded from the rostral medullary reticular formation before and after intraventricular infusion of crh in freely behaving newts and newts para ... | 2012 | 22137972 |
| tetrodotoxin levels in larval and metamorphosed newts (taricha granulosa) and palatability to predatory dragonflies. | some populations of the newt taricha granulosa possess extremely high concentrations of the neurotoxin tetrodotoxin (ttx). tetrodotoxin is present in adult newts and their eggs, but has been assumed to be absent from the larval stage. we tested larval and metamorphosed juveniles for the presence of ttx and evaluated the palatability of these developmental stages to predatory dragonfly nymphs. all developmental stages retained substantial quantities of ttx and almost all individuals were unpalata ... | 2011 | 21459104 |
| toxicity and population structure of the rough-skinned newt (taricha granulosa) outside the range of an arms race with resistant predators. | species interactions, and their fitness consequences, vary across the geographic range of a coevolutionary relationship. this spatial heterogeneity in reciprocal selection is predicted to generate a geographic mosaic of local adaptation, wherein coevolutionary traits are phenotypically variable from one location to the next. under this framework, allopatric populations should lack variation in coevolutionary traits due to the absence of reciprocal selection. we examine phenotypic variation in te ... | 2016 | 27066249 |
| effects of temperature on embryonic and early larval growth and development in the rough-skinned newt (taricha granulosa). | we investigated the effects of temperature on the growth and development of embryonic and early larval stages of a western north american amphibian, the rough-skinned newt (taricha granulosa). we assigned newt eggs to different temperatures (7, 14, or 21°c); after hatching, we re-assigned the newt larvae into the three different temperatures. over the course of three to four weeks, we measured total length and developmental stage of the larvae. our results indicated a strong positive relationshi ... | 2015 | 25965021 |
| the role of corticosterone and toxicity in the antipredator behavior of the rough-skinned newt (taricha granulosa). | a variety of mechanisms are responsible for enabling an organism to escape a predatory attack, including behavioral changes, alterations in hormone levels, and production and/or secretion of toxins. however, these mechanisms are rarely studied in conjunction with each other. the rough-skinned newt (taricha granulosa) is an ideal organism to examine the relationships between these mechanisms because its behavioral displays and toxin secretion during a predator attack are well documented and readi ... | 2015 | 25556312 |
| corticosterone suppresses vasotocin-enhanced clasping behavior in male rough-skinned newts by novel mechanisms interfering with v1a receptor availability and receptor-mediated endocytosis. | in rough-skinned newts, taricha granulosa, exposure to an acute stressor results in the rapid release of corticosterone (cort), which suppresses the ability of vasotocin (vt) to enhance clasping behavior. cort also suppresses vt-induced spontaneous activity and sensory responsiveness of clasp-controlling neurons in the rostromedial reticular formation (rf). the cellular mechanisms underlying this interaction remain unclear. we hypothesized that cort blocks vt-enhanced clasping by interfering wit ... | 2015 | 25528549 |
| identification and characterization of mesotocin and v1a-like vasotocin receptors in a urodele amphibian, taricha granulosa. | the cdna sequences encoding the mesotocin receptor (mtr) and vasotocin 1a receptor (vtr-1a) were identified in a urodele amphibian, the rough-skinned newt, taricha granulosa. saturation binding of [(3)h]oxytocin (ot) to the taricha mtr (tmtr) was best fit by a two-state model; a high affinity-low abundance site and a lower affinity-high abundance site. competition-binding studies found the following rank-order affinities for the tmtr: mesotocin (mt)>ot≈vasotocin (vt)>vasopressin (vp)>isotocin (i ... | 2011 | 20920503 |
| brainstem reticulospinal neurons are targets for corticotropin-releasing factor-induced locomotion in roughskin newts. | stress-induced release or central administration of corticotropin-releasing factor (crf) enhances locomotion in a wide range of vertebrates, including the roughskin newt, taricha granulosa. although crf's stimulatory actions on locomotor behavior are well established, the target neurons through which crf exerts this effect remain unknown. to identify these target neurons, we utilized a fluorescent conjugate of crf (crf-tamra 1) to track this peptide's internalization into reticulospinal and othe ... | 2010 | 19968991 |
| identification of brain target neurons using a fluorescent conjugate of corticotropin-releasing factor. | corticotropin-releasing factor (crf) is a peptide well known for its role in coordinating various neuroendocrine, autonomic, and behavioral components of the vertebrate stress response, including rapid enhancement of locomotor activity. although crf's locomotor enhancing properties are well documented, the neuronal mechanisms and specific target neurons that underlie the peptide's effect on locomotor behavior remain poorly understood. in the present study, we describe the synthesis and functiona ... | 2009 | 19481009 |
| fluoxetine potentiates the effects of corticotropin-releasing factor on locomotor activity and serotonergic systems in the roughskin newt, taricha granulosa. | the anxiety- and stress-related neuropeptide corticotropin-releasing factor (crf) elicits behavioral changes in vertebrates including increases in behavioral arousal and locomotor activity. intracerebroventricular injections of crf in an amphibian, the roughskin newt (taricha granulosa), induces rapid increases in locomotor activity in both intact and hypophysectomized animals. we hypothesized that this crf-induced increase in locomotor activity involves a central effect of crf on serotonergic n ... | 2009 | 19409390 |
| identification of mesotocin and vasotocin nucleotide sequences in two species of urodele amphibian. | we amplified and identified, for the first time in urodele amphibians, cdna sequences that encode preprovasotocin (preprovt) and prepromesotocin (prepromt) from two distinct urodelian species, taricha granulosa (the rough-skinned newt) and plethodon shermanii (the spotted salamander). each of these cdna sequences encoded proteins that contained the characteristics of known neurohypophysial peptide precursors; each sequence consisting of (1) a signal peptide, (2) vt- or mt-like peptides, (3) neur ... | 2009 | 19063891 |
| endocannabinoids mediate the effects of acute stress and corticosterone on sex behavior. | for animals in the wild, survival depends on being able to detect and respond rapidly to danger by switching from risky (e.g. conspicuous courtship) to survival-oriented behaviors. very little is known about the hormonal or neuroendocrine mechanisms that control the rapid switch in behavioral state that occurs when an animal detects threats or other stressors. prior studies with rough-skinned newts (taricha granulosa), an amphibian model, found that stress-induced suppression of male sexual beha ... | 2007 | 17095597 |
| delta and mu opioid receptors from the brain of a urodele amphibian, the rough-skinned newt taricha granulosa: cloning, heterologous expression, and pharmacological characterization. | two full-length cdnas, encoding delta (delta) and mu (mu) opioid receptors, were cloned from the brain of the rough-skinned newt taricha granulosa, complementing previous work from our laboratory describing the cloning of newt brain kappa (kappa) and orl1 opioid receptors. the newt delta receptor shares 82% amino acid sequence identity with a frog delta receptor and lower (68-70%) identity with orthologous receptors cloned from mammals and zebrafish. the newt mu receptor shares 79% sequence iden ... | 2006 | 16375901 |
| identification of roughskin newt medullary vasotocin target neurons with a fluorescent vasotocin conjugate. | arginine8 vasotocin (avt), a neurohypophyseal peptide in nonmammalian vertebrates, plays a key role in the regulation of social behaviors related to reproduction. in male roughskin newts (taricha granulosa), avt is an important facilitator of several reproductive behaviors, including courtship clasping of females. although avt is known to act in certain brain regions and avt receptors have been localized to some extent, specific target neurons for this peptide have not been identified in any spe ... | 2005 | 16175544 |
| cloning, heterologous expression and pharmacological characterization of a kappa opioid receptor from the brain of the rough-skinned newt, taricha granulosa. | a full-length cdna that encodes a kappa (kappa) opioid receptor has been isolated from the brain of a urodele amphibian, the rough-skinned newt taricha granulosa. the deduced protein contains 385 amino acids and possesses features commonly attributed to g protein-coupled receptors, such as seven putative transmembrane domains. the newt kappa receptor has 75% sequence identity to kappa opioid receptors cloned from mammals, and 66% sequence identity to the kappa opioid receptor reported for the ze ... | 2005 | 15956349 |
| cloning proenkephalin from the brain of a urodele amphibian (taricha granulosa) using a dor-specific primer in a 3'race reaction. | a large cdna fragment that codes for proenkephalin (penk) was cloned from the rough-skinned newt, taricha granulosa (genbank accession: ay817670). this 1299-bp penk cdna extends from the poly(a) sequence on the 3' end into the 5'-utr (221bp) upstream of an open reading frame that codes for 264 amino acids and a stop codon. within the precursor are five met-enkephalin sequences and two c-terminally extended forms of met-enkephalin (yggfmrgv and yggfmry). the organization of the opioid core sequen ... | 2005 | 15935163 |
| parallel arms races between garter snakes and newts involving tetrodotoxin as the phenotypic interface of coevolution. | parallel "arms races" involving the same or similar phenotypic interfaces allow inference about selective forces driving coevolution, as well as the importance of phylogenetic and phenotypic constraints in coevolution. here, we report the existence of apparent parallel arms races between species pairs of garter snakes and their toxic newt prey that indicate independent evolutionary origins of a key phenotype in the interface. in at least one area of sympatry, the aquatic garter snake, thamnophis ... | 2005 | 15856788 |
| neuroanatomical distribution of vasotocin and mesotocin in two urodele amphibians (plethodon shermani and taricha granulosa) based on in situ hybridization histochemistry. | previous research suggests that considerable species-specific variation exists in the neuroanatomical distributions of arginine vasotocin (avt) and mesotocin (mst), non-mammalian homologues of vasopressin and oxytocin. an earlier study in rough-skinned newts (taricha granulosa) indicated that the neuroanatomical distribution of cells labeled for avt-immunoreactivity (ir) was greater in this urodele amphibian than in any other species. it was unknown whether the widespread distribution of avt-ir ... | 2005 | 15713271 |
| isolation by distance and post-glacial range expansion in the rough-skinned newt, taricha granulosa. | allozymes and mitochondrial dna sequences were used to examine the phylogeographical history of the rough-skinned newt, taricha granulosa, in western north america. nineteen populations were analysed for allozyme variation at 45 loci, and 23 populations were analysed for cytochrome b sequence variation. both data sets agree that populations in the southern part of the range are characterized by isolation by distance, whereas northern populations fit the expectations of a recent range expansion. ... | 2005 | 15643966 |
| a resistant predator and its toxic prey: persistence of newt toxin leads to poisonous (not venomous) snakes. | the common garter snake (thamnophis sirtalis) preys upon the rough-skinned newt (taricha granulosa), which contains the neurotoxin tetrodotoxin (ttx) in the skin. ttx is toxic, large quantities are present in a newt, and highly resistant snakes have the ability to ingest multiple newts; subsequently snakes harbor significant amounts of active toxin in their own tissues after consuming a newt. snakes harbor ttx in the liver for 1 mo or more after consuming just one newt, and at least 7 wk after c ... | 2004 | 15609827 |
| molecular parentage analysis in experimental newt populations: the response of mating system measures to variation in the operational sex ratio. | molecular studies of parentage have been extremely influential in the study of sexual selection in the last decade, but a consensus statistical method for the characterization of genetic mating systems has not yet emerged. here we study the utility of alternative mating system measures by experimentally altering the intensity of sexual selection in laboratory-based breeding populations of the rough-skinned newt. our experiment involved skewed sex ratio (high sexual selection) and even sex ratio ... | 2004 | 15459877 |
| no evidence for an endosymbiotic bacterial origin of tetrodotoxin in the newt taricha granulosa. | tetrodotoxin (ttx) is a potent neurotoxin which is known to occur in numerous taxa, including newts. the origin of ttx is unknown, but production by symbiotic bacteria is suspected for some groups. using pcr primers that specifically amplify 16s rrna genes of bacteria, we examined tissues from rough-skin newts, taricha granulosa, for the presence of bacteria which may produce ttx. no amplification of bacterial dna was seen in samples taken from skin, liver, gonads or oviposited eggs-tissues know ... | 2004 | 15302530 |
| a predictive model to estimate total skin tetrodotoxin in the newt taricha granulosa. | we developed a predictive model to estimate the total amount of tetrodotoxin (ttx) in the skin of individual newts (taricha granulosa) based on measures of the amount of ttx present in dorsal skin. we found that regions of skin on a newt could be reliably differentiated using granular gland density and that patterns of variation in granular gland density matched intra-individual variation in ttx levels. tetrodotoxin is uniformly distributed in dorsal skin and ttx levels in dorsal skin are strong ... | 2004 | 15033321 |
| neuroendocrinology of context-dependent stress responses: vasotocin alters the effect of corticosterone on amphibian behaviors. | the ability of an animal to respond with appropriate defensive behaviors when confronted with an immediate threat can affect its survival and reproductive success. in the roughskin newt (taricha granulosa), exogenous corticosterone (cort) rapidly blocks and vasotocin (vt) enhances reproductive behaviors (mainly clasping behavior). electrophysiological studies have shown that pretreatment of male taricha with vt counteracts the inhibitory effects of cort on neuronal activity in the medulla. to te ... | 2003 | 12614653 |
| validation of bateman's principles: a genetic study of sexual selection and mating patterns in the rough-skinned newt. | few studies have influenced thought on the nature of sexual selection to the extent of the classic paper of a. j. bateman on mating patterns in drosophila. however, interpretation of his study remains controversial, and a lack of modern empirical evidence prevents a consensus with respect to the perceived utility of bateman's principles in the study of sexual selection. here, we use a genetic study of natural mating patterns in the rough-skinned newt, taricha granulosa, to investigate the concor ... | 2002 | 12573067 |
| behavioral neuroendocrinology of vasotocin and vasopressin and the sensorimotor processing hypothesis. | vasotocin (avt) and vasopressin (avp) are potent modulators of social behaviors in diverse species of vertebrates. this review addresses questions about how and where avt and avp act to modulate social behaviors, focusing on research with an amphibian model (taricha granulosa). in general, the behaviorally important avt and avp neurons occur in the forebrain and project to sites throughout the brain. social behaviors are modulated by avt and avp acting at multiple sites in the brain and at multi ... | 2002 | 12381329 |
| tetrodotoxin levels of the rough-skin newt, taricha granulosa, increase in long-term captivity. | we investigated the persistence of the neurotoxin tetrodotoxin (ttx) in individual captive newts (taricha granulosa) from the willamette valley of oregon using a non-lethal sampling technique. we found that the ttx levels of newts held in the laboratory for 1 yr increased. ttx stereoisomer-analog profiles were not affected by captive husbandry. levels of ttx were high in newts from our study population and we observed substantial within population variation in quantitative levels of ttx. females ... | 2002 | 12165318 |
| topping off: a mechanism of first-male sperm precedence in a vertebrate. | competition among the sperm of rival males is an important evolutionary phenomenon in many organisms. yet, despite extensive research on sperm competition in some vertebrate taxa, very little progress has been made on this topic in amphibians. urodele amphibians (newts and salamanders) are of particular interest to theories of sperm competition because most urodele females--in contrast to other vertebrate females--control the transfer of sperm from the male. here we present a molecular study of ... | 2002 | 11842198 |
| rapid changes in monoamine levels following administration of corticotropin-releasing factor or corticosterone are localized in the dorsomedial hypothalamus. | monoaminergic systems are important modulators of the neuroendocrine, autonomic, and behavioral responses to stress-related stimuli. the male roughskin newt (taricha granulosa) was used as a model system to investigate the effects of corticotropin-releasing factor (crf) or corticosterone administration on tissue concentrations of norepinephrine, epinephrine, dopamine, 3,4-dihydroxyphenylacetic acid, serotonin, and 5-hydroxyindoleacetic acid (5-hiaa) in microdissected brain areas. intracerebroven ... | 2001 | 11300710 |
| vasotocin stimulates appetitive responses to the visual and pheromonal stimuli used by male roughskin newts during courtship. | it is now well established that vasotocin (avt) and its mammalian homologue vasopressin influence various social behaviors in vertebrates, but less is known about the mechanisms through which these peptides modulate behavior. in male roughskin newts, taricha granulosa, avt stimulates a courtship behavior, amplectic clasping. three general explanations for how avt affects male courtship behavior have been considered: by enhancing a central state of sexual motivation, by affecting sensorimotor int ... | 2000 | 10964521 |
| corticosteroid actions from neuronal membrane to behavior: neurophysiological mechanisms underlying rapid behavioral effects of corticosterone. | investigation of the rapid suppression of male courtship clasping behavior by corticosterone in roughskin newts (taricha granulosa) has led to the identification of a specific neuronal membrane receptor for this stress steroid. this paper describes studies of the neurophysiological effects of the rapid, membrane receptor mediated action of corticosterone on neurons that are involved in the control of clasping. in freely behaving newts, medullary neurons, including reticulospinal neurons, process ... | 2000 | 10949082 |
| a subset of kappa opioid ligands bind to the membrane glucocorticoid receptor in an amphibian brain. | previous studies demonstrated that a membrane receptor for glucocorticoids (mgr) exists in neuronal membranes from the roughskin newt (taricha granulosa) and that this receptor appears to be a g protein-coupled receptor (gpcr). the present study investigated the question of whether this mgr recognizes nonsteroid ligands that bind to cognate receptors in the gpcr superfamily. to address this question, ligand-binding competition studies evaluated the potencies of various ligands to displace [3h]co ... | 2000 | 10875228 |
| partial purification and biochemical characterization of a membrane glucocorticoid receptor from an amphibian brain. | a membrane receptor for corticosterone (mgr) in the brain of the roughskin newt (taricha granulosa) has been previously identified. this manuscript reports the evaluation of several chromatographic resins for enrichment of the newt mgr solubilized from neuronal membranes. a protein with an apparent molecular weight of 63 kda was purified to near homogeneity following sequential purification using ammonium sulfate fractionation, wheat germ agglutinin (wga)-agarose chromatography, hydroxylapatite ... | 2000 | 10822010 |
| sexual dimorphism in numbers of vasotocin-immunoreactive neurons in brain areas associated with reproductive behaviors in the roughskin newt. | vasotocin (vt) and vasopressin control many endocrine and neuroendocrine functions, including the regulation of reproductive behaviors. in the roughskin newt (taricha granulosa), vt administration can enhance courtship behaviors in males and egg-laying behaviors in females. this study used immunohistochemistry to investigate whether there are sex differences in vt in specific brain areas, and whether these differences persist in nonbreeding animals. numbers of vt immunoreactive (ir) cell bodies ... | 2000 | 10642450 |
| behavior of hindbrain neurons during the transition from rest to evoked locomotion in a newt. | trains of electrical stimuli were delivered to the mesencephalic 'locomotor region' in the rough skin newt. the current (3-12 mca) and the interstimulus interval (100 to 200 ms) were adjusted so that locomotion arose in approximately 10 s, or so that the train remained subthreshold for initiation of locomotion. impulses of single neurons in the hindbrain were recorded during the transition period from rest to locomotion. time-locked synaptic responses were bi- or unimodal with typical latencies ... | 1999 | 10635724 |
| evolutionary response of predators to dangerous prey: preadaptation and the evolution of tetrodotoxin resistance in garter snakes. | coevolutionary interactions typically involve only a few specialized taxa. the factors that cause some taxa and not others to respond evolutionarily to selection by another species are poorly understood. preadaptation may render some species predisposed for evolutionary response to new pressures, whereas a lack of genetic variation may limit the evolutionary potential of other taxa. we evaluate these factors in the predator-prey interaction between toxic newts (taricha granulosa) and their resis ... | 1999 | 28565572 |
| the effects of sex steroids and vasotocin on behavioral responses to visual and olfactory sexual stimuli in ovariectomized female roughskin newts. | previous studies have found that vasotocin (avt) administration to male roughskin newts (taricha granulosa) enhances courtship clasping as well as appetitive responses to specific sexual stimuli and that treating female newts with androgens plus avt induces the expression of male-typical courtship clasping (the selective clasping of females). however, the unique and/or interactive effects of sex steroids and avt on appetitive responses to specific sexual stimuli have not yet been determined. to ... | 2003 | 14613725 |
| tetrodotoxin levels in eggs of the rough-skin newt, taricha granulosa, are correlated with female toxicity. | we quantified the amount of the neurotoxin tetrodotoxin (ttx) present in females and newly deposited eggs of the rough-skin newt, taricha granulosa, to examine the relationship between the toxicity of an individual female and the toxicity of her eggs. we found high levels of ttx in individual eggs as well as substantial variation among clutches. variation in the amount of ttx per egg within individual clutches was extremely low. female skin toxicity was positively correlated with the mean egg to ... | 2003 | 12956503 |
| steroid-neuropeptide interactions that control reproductive behaviors in an amphibian. | investigations into the neuroendocrine regulation of reproductive behaviors in an amphibian (taricha granulosa) reveal the same basic repertoire of chemical messengers as regulators of male behaviors in other vertebrates. these studies have identified seasonal neural interactions between gonadal steroids and neuropeptides that facilitate male courtship behavior. in addition, this species has served to elucidate how stress-induced suppression of courtship is mediated by corticosterone action thro ... | 1994 | 7938356 |
| rapid neurophysiological effects of corticosterone on medullary neurons: relationship to stress-induced suppression of courtship clasping in an amphibian. | courtship clasping of females by male roughskin newts (taricha granulosa) is rapidly blocked by exposure to corticosterone (cort). this behavioral effect appears to result from cort binding to a receptor in neuronal membranes. the present study investigated effects of intraperitoneal cort administration on neurophysiological properties of extracellularly recorded single medullary neurons in acutely prepared newts. cort produced multiple neurophysiological effects that emerged within 3 min of inj ... | 1993 | 8413818 |
| sex steroids and vasotocin interact in a female amphibian (taricha granulosa) to elicit female-like egg-laying behavior or male-like courtship. | female egg-laying behaviors and male amplectic clasping behaviors in the rough-skinned newt (taricha granulosa) are similar in that animals clasp an object. in the case of egg-laying, females clasp submerged inanimate objects, whereas in amplexus, males clasp conspecific females. considering these behavioral similarities and differences, we investigated the possibility that gonadal steroids and vasotocin (avt) interact to control egg-laying behaviors, as has been shown for the control of amplexu ... | 1992 | 1612562 |
| crocidolite asbestos fibers undergo size-dependent microtubule-mediated transport after endocytosis in vertebrate lung epithelial cells. | the large respiratory epithelial cells within primary cultures of newt (taricha granulosa) lung are uniquely suited for high resolution video-enhanced light-microscopic studies. we show here that these cells incorporate crocidolite asbestos fibers within 18 h by endocytosis. once inside the cell, fibers less than 5 microns in length are seen by video light microscopy to undergo saltatory transport at a maximum velocity of 1.18 microns/s. by contrast, fibers over 5 microns long rarely exhibit sal ... | 1991 | 1893384 |
| temperature acclimation of respiratory function in the salamander taricha granulosa. | the effect of acute and chronic temperature change on oxygen uptake (vo2) and the respiratory properties of blood was determined in the newt, taricha granulosa. acclimation to 20-24 degrees c for 4 weeks caused a significant increase in hemoglobin concentration (6.5-9.5 g/dl) and o2 capacity of blood but no change in oxygen affinity compared with animals acclimated to 4-6 degrees c. cold acclimated animals had a reverse bohr effect compared with warm acclimated animals (dlogp 50/dph = +0.13 and ... | 1991 | 1961998 |
| comparative neuroanatomy of vasotocin and vasopressin in amphibians and other vertebrates. | this review focuses on the neuroanatomical distribution of vasotocin (vt) and vasopressin (vp) and presents a comparative analysis of brain areas in which vt and vp cell bodies have been reported in fish, amphibians, reptiles, birds and mammals. a comparison of information from previous neuroanatomical studies of vt and vp with findings from a recent study of vt in an amphibian (taricha granulosa) supports the conclusions that the vt/vp system can be subdivided into identifiable groups of cell b ... | 1998 | 9826998 |
| solubilization and pharmacological characterization of a glucocorticoid membrane receptor from an amphibian brain. | physiological functions of steroid hormones involve activation of intracellular receptors as well as poorly understood membrane receptors. we report the pharmacological characterization of a solubilized corticosterone receptor from neuronal membranes. this receptor previously was shown to localize with plasma membrane subcellular fractions and to be involved in the modulation of courtship behaviors in the roughskin newt (taricha granulosa). we describe procedures with non-ionic detergents that s ... | 1998 | 9780023 |
| neuroanatomical distribution of vasotocin in a urodele amphibian (taricha granulosa) revealed by immunohistochemical and in situ hybridization techniques. | immunohistochemical and in situ hybridization techniques were used to investigate the neuroanatomical distribution of arginine vasotocin-like systems in the roughskin newt (taricha granulosa). vasotocin-like-immunoreactive neuronal cell bodies were identified that, based on topographical position, most likely, are homologous to groups of vasopressin-immunoreactive neuronal cell bodies described in mammals, including those in the bed nucleus of the stria terminalis, medial amygdala, basal septal ... | 1997 | 9268116 |