| tissue lesions of tiger salamanders (ambystoma tigrinum): relationship to sewage effluents. | a population of facultative neotenous tiger salamanders (a. tigrinum) inhabiting a sewage lagoon at reese afb, hurlwood, texas, was found to have an exceptionally high rate of spontaneous tissue lesions. the population is composed of an estimated 28,000 large, reproductively mature larvae that are restricted to the lagoon. only about 17% of the population metamorphoses normally. in contrast, tiger salamanders from uncontaminated lagoons in the same general vicinity metamorphose normally; however ... | 1978 | 280184 |
| the effects of ergocornine on tail height, spontaneous and t4-induced metamorphosis and thyroidal uptake of radioiodide in neotenic ambystoma tigrinum. | | 1976 | 946962 |
| the life cycle of haematoloechus coloradensis cort 1915 (digenea: plagiorchiidae), with emphasis on host susceptibility to infection. | mother and daughter sporocysts and xiphidiocercariae of haematoloechus coloradensis develop in the snail, physa virgata. cercariae penerate and encyst in dragonfly nymphs, tramea sp., libellula sp., anax sp., and in damselfly nymphs, enallagma spp. upon ingestion by the vertebrate host, metacercariae excyst and migrate into the lungs where they mature. haematoloechus coloradensis is specific for its definitive host, r. pipiens, but shows some development in ambystoma tigrinum. although h. colora ... | 1975 | 1080802 |
| localization of gabaa receptor subtypes in the tiger salamander retina. | dry autoradiography was used to determine the distribution of gabaa binding sites in tiger salamander retina. high-affinity binding of [3h]-flunitrazepam [( 3h]-fnz) was used to localize benzodiazepine receptors (bzr) and [3h]-muscimol was used to localize the gabaa recognition site. specific [3h]-fnz binding was present only in the inner retina, primarily in the inner plexiform layer (ipl). co-incubation with gaba enhanced [3h]-fnz binding by 20-50%. [3h]-muscimol binding was found throughout t ... | 1992 | 1310871 |
| a slowly inactivating k+ current in retinal ganglion cells from postnatal rat. | the whole-cell configuration of the patch-clamp technique was used to study voltage-gated k+ conductances in retinal ganglion cells from postnatal rat. retinal ganglion cells were fluorescently labeled in situ, dissociated from the retina, and maintained in culture. with physiological solutions in the bath and the pipette, depolarizing voltage steps from physiological holding potentials activated na(+)-(ina), ca2+ (ica), and k(+)-currents studied previously in retinal ganglion cells. here we rep ... | 1992 | 1558829 |
| species differences in amphibian olfactory neuron reactivity to a monoclonal antibody. | a monoclonal antibody immunostained a subpopulation of olfactory sensory neurons in cryostat sections of the olfactory mucosa of the grass frog, rana pipiens, and the bullfrog, rana catesbeiana. however, in the olfactory tissues of the african clawed frog, xenopus laevis, only mucus and mucus-secreting components were stained, and no cell-specific immunoreactivity was seen in the tiger salamander, ambystoma tigrinum. this antibody is a useful marker of olfactory neuronal subpopulations in some a ... | 1992 | 1617462 |
| axial motor organization in postmetamorphic tiger salamanders (ambystoma tigrinum): a segregation of epaxial and hypaxial motor pools is not necessarily associated with terrestrial locomotion. | the axial motor column has undergone a major reorganization during the evolution of vertebrates. in aquatic anamniotes including lampreys, goldfish, and mudpuppies, epaxial and hypaxial motoneurons are intermingled in the column. in contrast, epaxial and hypaxial motoneurons are spatially segregated in water snakes, rats, and monkeys, apparently as a consequence of an isomorphic mapping of motoneuron location onto the position of innervated muscle in the embryonic myotome. the presence of these ... | 1992 | 1633553 |
| light-dependent delay in the falling phase of the retinal rod photoresponse. | using suction electrodes, photocurrent responses to 100-ms saturating flashes were recorded from isolated retinal rods of the larval-stage tiger salamander (ambystoma tigrinum). the delay period (tc) that preceded recovery of the dark current by a criterion amount (3 pa) was analyzed in relation to the flash intensity (if), and to the corresponding fractional bleach (r*0/rtot) of the visual pigment; r*0/rtot was compared with r*s/rtot, the fractional bleach at which the peak level of activated t ... | 1992 | 1739680 |
| immunologic conservation of the fiber cell beaded filament. | lenses were obtained from the eyes of four different classes of chordates, including mammalia (rat, mouse, cow, human), aves (chicken), amphibia (tiger salamander), and osteichthyes (steelhead), as well as from one mollusca (squid). buffer soluble, urea soluble and urea insoluble fractions were prepared from each, and probed by western blot analysis for the presence of the lens fiber cell 115 and 49 kd beaded filament proteins. application of both polyclonal and monoclonal antibodies revealed th ... | 1991 | 1889232 |
| effect of potassium ions and membrane potential on the na-ca-k exchanger in isolated intact bovine rod outer segments. | two recent studies reported that na-ca exchange in the outer segments of tiger salamander rod photoreceptors (cervetto, l., lagnado, l., perry, r. j., robinson, d. w., and mcnaughton, p. a. (1989) nature 337, 740-743) and of bovine rod photoreceptors (schnetkamp, p. p. m., basu, d. k., and szerencsei, r. t. (1989) am. j. physiol. 257, c153-157) requires and transports k+ in a 4na/(1ca+1k) stoichiometry. in this study, we have examined the effects of k+ ions and membrane potential on the kinetics ... | 1991 | 1985892 |
| the lateral spread of signal between bipolar cells of the tiger salamander retina. | when mapped with a small spot of light, the central receptive fields of bipolar cells in the salamander retina are much larger than the extent of bipolar cell dendrites. furthermore responses of bipolar cells to distant spots of light are considerably delayed relative to proximal spots. using quantitative modelling, electrical coupling between bipolar cells is examined and rejected as a sufficient explanation of the data. an active process appears to shape signal waveform as signals spread later ... | 1990 | 2357478 |
| distribution of potassium conductance in mammalian müller (glial) cells: a comparative study. | the distribution of k+ conductance across the surface of retinal müller cells was determined in 5 mammalian species--rabbit, guinea pig, mouse, owl monkey, and cat--and in tiger salamander. potassium conductance was measured by monitoring cell depolarizations evoked by focal ejections of a high-k+ solution onto the surface of freshly dissociated cells. this technique measured the total k+ conductance of a given cell region (regional conductance), i.e., the specific k+ conductance times the total ... | 1987 | 2441009 |
| regulation of potassium levels by müller cells in the vertebrate retina. | the membrane properties of müller cells, the principal glial cells of the vertebrate retina, have been characterized in a series of physiological experiments on freshly dissociated cells. in species lacking a retinal circulation (tiger salamander, rabbit, guinea pig), the end-foot of the müller cell has a much higher k+ conductance than do other cell regions. in species with retinal circulation (mouse, cat, owl monkey) the k+ conductance of the end-foot is greater than the conductance of the pro ... | 1987 | 2441827 |
| induction of cloacal and dermal skin glands of tiger salamander larvae, (ambystoma tigrinum): effects of testosterone and prolactin. | treatment of male and female tiger salamander larvae with testosterone (0.3 micrograms/g body weight/day) induced precocious formation of ventral cloacal glands and stimulated proliferation and differentiation of mucous and granular (serous) glands in the ventral dermis of the skin. lower doses of testosterone produced no visible glandular effects but did cause hyperemia and edema in the cloacal region. prolactin (0.5 micrograms/g body weight/day) enhanced the action of testosterone on the cloac ... | 1989 | 2707581 |
| mauthner neurons survive metamorphosis in anurans: a comparative hrp study on the cytoarchitecture of mauthner neurons in amphibians. | giant medullary neurons were revealed in adult xenopus laevis and rana esculenta following hrp injections to the spinal cord. these neurons were identified as mauthner neurons because (1) they have the same position and orientation as the larval mauthner neurons, i.e., they lie at the level of the viiith nerve root. (2) they have two large dendritic trees that for each species are similar to those of the larval mauthner neurons, (3) they are clearly distinguishable from other large reticular neu ... | 1986 | 3081602 |
| characterization of renal prolactin-binding sites of two amphibians (ambystoma tigrinum and rana catesbeiana) and a reptile (pseudemys scripta elegans). | the specific binding of 125i-ovine prolactin (oprl) to renal membrane preparations from pseudemys scripta elegans, ambystoma tigrinum, and rana catesbeiana was characterized. all three membranes showed specific oprl binding that was dependent upon time, temperature, ph, and membrane concentration. scatchard analysis of the binding of 125i-oprl revealed high-affinity sites with ka values of 2.1 x 10(10), 3.6 x 10(10), and 1.25 x 10(10) m-1 for kidney membranes of pseudemys, ambystoma, and rana, r ... | 1987 | 3495632 |
| adenohypophysial-thyroid activity of the tiger salamander, ambystoma tigrinum, as a function of metamorphosis and captivity. | the aim of this study was to determine the timing of adenohypophysial activation during metamorphosis of the tiger salamander, ambystoma tigrinum. it consisted of two parts: 1) determination of plasma thyroid hormone concentrations and analysis of thyroid gland histology as a function of metamorphic stage and 2) analysis of the time-course of uptake of 125i by the thyroids during metamorphosis as an indicator of endogenous thyrotropin (tsh) levels. significant increases in both triiodothyronine ... | 1987 | 3598513 |
| effects of metamorphosis and captivity on the in vitro sensitivity of thyroid glands from the tiger salamander, ambystoma tigrinum, to bovine thyrotropin. | the sensitivity of thyroid glands from the tiger salamander, ambystoma tigrinum, to bovine thyrotropin (btsh) was tested in vitro. thyroids were taken from subjects representing metamorphic stages i (premetamorphic larvae), ii (onset of climax), and vii (completion of gill resorption), as well as from captivity control larvae. exogenous tsh reduced the cumulative uptake of 125i in vitro by thyroids from stage i larvae after 24 and 48 hr. the capacity of thyroids to release thyroxine (t4) in vitr ... | 1987 | 3623072 |
| morphology of physiologically identified bipolar cells in the retina of the tiger salamander, ambystoma tigrinum. | intracellular recordings of the light responses of bipolar cells were made in the isolated perfused retina of the larval tiger salamander by microelectrodes filled with a 1% solution of the enzyme horseradish peroxidase (hrp). two classes of bipolar cell were identified in terms of their responses to luminous spots and annuli centered upon their receptive fields: on-center cells, which depolarized in response to a centered spot and hyperpolarized in response to a concentric annulus, and off-cent ... | 1986 | 3793974 |
| cell membranes and paracellular resistances in isolated renal proximal tubules from rabbit and ambystoma. | transepithelial specific resistance (re) was measured in isolated and perfused rabbit proximal convoluted tubules by cable analysis and intracellular micro-electrode techniques were used to calculate the electrical resistances of the cell membranes and of the paracellular pathway. re was 16 +/- 2 omega cm2 and the space constant was 130 +/- 14 micron, n = 29. re was significantly increased by a decrease in temperature from 37 to 10 degrees c, and was practically abolished by nominal removal of c ... | 1986 | 3958978 |
| seasonal variations in spermatogenesis, testicular weights, vasa deferentia, and androgen levels in neotenic male tiger salamanders, ambystoma tigrinum. | significant seasonal changes were observed in spermatogenesis, testicular weights, vasa deferentia, and cloacal development as well as in plasma androgen levels (testosterone and dihydrotestosterone). androgen levels were highest in the fall and lowest during the period of spermatogenesis. low levels of androgens were also observed during the breeding season. diameter of the vasa deferentia corresponded to presence of stored spermatozoa and not to plasma androgen levels. testicular weights were ... | 1985 | 4054587 |
| inhibition of metamorphosis in ambystoma tigrinum by prolactin. | | 1970 | 4192946 |
| t3- and t4-induced rates of metamorphosis in immature and sexually mature larvae of ambystoma tigrinum (amphibia: caudata). | | 1974 | 4416765 |
| the relationship of acetylcholinesterase activity to optic fiber projections in the tiger salamander ambystoma tigrinum. | | 1973 | 4748957 |
| beta-endorphins (beta-ep) in amphibians: higher beta-ep levels during regenerating stages of anuran life cycle and immunocytochemical localization of beta-ep in regeneration blastemata. | plasma beta-endorphin (beta-ep) levels were measured at different stages of metamorphosis in anuran species, namely rana catesbeiana, r. pipiens, and xenopus laevis. the mean levels of beta-ep in tadpoles and postmetamorphic juveniles were significantly higher than adult levels in all three species examined. the pattern of high tadpole levels and low adult levels corresponds with the limb regeneration ability of the tadpole and restriction in the adult. we have also reported plasma beta-ep level ... | 1984 | 6094701 |
| differential ability of ambystoma tigrinum hepatic microsomes to produce mutagenic metabolites from polycyclic aromatic hydrocarbons and aromatic amines. | a number of carcinogenic aromatic amines when activated by liver microsomes from a salamander, ambystoma tigrinum, are mutagenic for salmonella tester strains sensitive to frameshift mutagens. however, 2 polycyclic aromatic hydrocarbons (pah) (benzo[alpha]pyrene (bap) and perylene) that are rendered mutagenic by mammalian microsomes are not activated by ambystoma mixed-function oxidases. bap was chosen for study because it is a well-known environmental carcinogen; perylene, an isomer of bap, has ... | 1982 | 6288233 |
| evidence for orthogonal arrays of particles in the plasma membranes of olfactory and vomeronasal sensory neurons of vertebrates. | plasma membranes of sensory neurons from the olfactory and vomeronasal neuroepithelia of the male rat and olfactory neuroepithelium of the tiger salamander (ambystoma tigrinum) have been examined, using the freeze-fracture technique, for the presence and morphology of orthogonal arrays of particles (oap). numerous oap were scattered on the p-face of plasma membranes of the dendrites and cell bodies from rat vomeronasal sensory neurons. the oap were 720 +/- 200 nm2 in area and they consisted of 4 ... | 1983 | 6311991 |
| a comparative study of potassium-induced relaxation in vascular smooth muscle of tiger salamanders and rats. | this study compares potassium-induced relaxation in vascular tissue of an amphibian (ambystoma tigrinum) and a mammal (rat). aortas (salamanders) and tail arteries (rats) were cut into helical strips for isometric force recording. after norepinephrine-induced contraction in potassium-free solution, arteries relaxed in response to added potassium (1-20 mmol/l). potassium-induced relaxation was greater in rat tail arteries than in salamander aortas. half-maximal relaxation occurred at a potassium ... | 1984 | 6331206 |
| a resonance raman study of ambystoma tigrinum hemoglobins: evidence for intraspecies hemepocket variations. | using resonance raman difference spectroscopy, the raman-active vibrational modes of hemoglobins from adult, neotenic, and larval forms of the salamander, ambystoma tigrinum have been compared to each other and to human hemoglobin. the local heme environment of the adult and neotenic proteins were identical and differed from that of the larval protein. differences were observed in modes sensitive to porphyrin pi electron density and axial ligation. systematic differences were also observed betwe ... | 1984 | 6518767 |
| plasma t4 and t3 levels in ambystoma tigrinum at various stages of metamorphosis. | | 1981 | 7227809 |
| synaptic action mediating cone responses to annular illumination in the retina of the larval tiger salamander. | 1. responses of salamander cones to steps of light on their surrounding area were intracellularly recorded through micropipettes filled with 2 m-potassium acetate or 2 m-potassium chloride. 2. using 2 m-potassium acetate, cone step responses showed a larger relaxation for a 1100 micrometers diameter spot than for a 100 micrometers spot, but dim annular illumination failed to evoke any detectable response. with 2 m-potassium chloride the larger spot or an anulus evoked responses that were mainly ... | 1981 | 7230033 |
| hormone-induced ovulation in ambystoma tigrinum: influence of prolactin and thyroxine. | treatment of hypophysectomized or intact neotenic tiger salamander larvae (ambystoma tigrinum) with ovine prolactin (prl) increased sensitivity of the ovary to the ovulation-inducing hormones, human chorionic gonadotropin and luteinizing hormone (lh). effects of pretreatment in vivo with prl or thyroxine (t4) on the responsiveness of ovarian fragments in vitro to ovulation-inducing agents, lh, or progesterone (prog) in the presence or absence of prl were observed. in november (prior to normal sp ... | 1981 | 7288386 |
| the multi-ion nature of the cgmp-gated channel from vertebrate rods. | 1. native cgmp-gated channels were studied in rod outer segments of the larval tiger salamander, ambystoma tigrinum. the alpha-subunit of the cgmp-gated channel, here referred to as the wild type (wt), and mutant channels were heterologously expressed in xenopus laevis oocytes. these channels were studied in excised membrane patches in the inside-out configuration and were activated by the addition of 100 or 500 microm cgmp. the current carried by monovalent cations was measured under voltage-cl ... | 1995 | 7473247 |
| effects of prolactin, growth hormone, and triiodothyronine on prolactin receptors in larval and adult tiger salamanders (ambystoma tigrinum). | the effects of porcine growth hormone (pgh) or ovine prolactin (oprl) alone and in combination with triiodothyronine (t3) on renal prl receptors were determined in both pre- and post-metamorphic tiger salamanders (ambystoma tigrinum). the protein hormones were given at a dose of 1.0 micrograms/gm body weight/day and the t3 was given at 10.0 ng/gm body weight/day. the duration of treatment was 7 days. effects on growth, and plasma thyroid hormone levels were also determined. ovine prl increased g ... | 1993 | 8354992 |
| peripheral projections of nervus terminalis lhrh-containing neurons in the tiger salamander, ambystoma tigrinum. | the peripheral projections of the nervus terminalis (nt) have been difficult to examine due to the weak immunoreactivity of the processes to various antibodies. we performed two experimental manipulations in the tiger salamander in an attempt to increase the luteinizing hormone-releasing hormone-immunoreactive (lhrh-ir) labelling in the peripheral processes of the nt:1) the nt was sectioned centrally, or 2) a 100 mg melatonin pellet was embedded subcutaneously for 3 days prior to sacrifice. foll ... | 1993 | 8364959 |
| d2-like dopamine receptors in amphibian retina: localization with fluorescent ligands. | dopamine induces several light adaptive changes in amphibian retina via receptors with d2-like pharmacology, but the identity of the primary target cells has not been determined. using a fluorescent probe consisting of a selective d2 antagonist, n-(p-aminophenethyl)-spiperone (naps), derivatized with the fluorophore bodipy (naps-bodipy), we identified the distribution of dopamine binding sites in the retina of two amphibians, post-metamorphic xenopus laevis and larval ambystoma tigrinum. specifi ... | 1993 | 8509497 |
| effect of changing temperature on the ionic permeation through the cyclic gmp-gated channel from vertebrate photoreceptors. | native cgmp-gated channels were studied in rod outer segments of the larval tiger salamander ambystoma tigrinum. the alpha subunit of the cgmp-gated channel from bovine rods, here referred to as the wild type (w.t.), and mutant channels were heterologously expressed in xenopus laevis oocytes. these channels were studied in excised membrane patches in the inside-out configuration and were activated by the addition of 100 or 500 microm cgmp. the effect of temperature on the ionic permeation was st ... | 1996 | 8744300 |
| equivalence of background and bleaching desensitization in isolated rod photoreceptors of the larval tiger salamander. | psychophysical experiments have shown an equivalence between sensitivity reduction by background light and by bleaches for the human scotopic system. we have compared the effects of backgrounds and bleaches on the light-sensitive membrane-current responses of isolated rod photoreceptors from the salamander ambystoma tigrinum. the quantum catch loss was factored out from the desensitization due to bleaching to give the fraction of "extra" desensitization due to adaptation. for backgrounds, desens ... | 1996 | 8894981 |
| interrenal function in larval ambystoma tigrinum. iv. acid-base balance and the renin-angiotensin system. | larval ambystoma tigrinum were cannulated nonocclusively in the truncus arteriosus and allowed to recover for 20-24 hr. in one group of animals a peritoneal cannula was inserted in order to induce acidosis through the injection of lactic acid (2 micromol/g). immediately following a control blood sample (hr 0), lactic acid was injected, and blood samples were collected at 1, 4, 8, and 24 hr and analyzed for ph, pco2, po2, [hco3-], and aldosterone. these animals exhibited a significant metabolic a ... | 1997 | 9000464 |
| the structure and precision of retinal spike trains. | assessing the reliability of neuronal spike trains is fundamental to an understanding of the neural code. we measured the reproducibility of retinal responses to repeated visual stimuli. in both tiger salamander and rabbit, the retinal ganglion cells responded to random flicker with discrete, brief periods of firing. for any given cell, these firing events covered only a small fraction of the total stimulus time, often less than 5%. firing events were very reproducible from trial to trial: the t ... | 1997 | 9144251 |
| thyroid hormone receptor genes of neotenic amphibians. | since thyroid hormones play a pivotal role in amphibian metamorphosis we used pcr to amplify dna fragments corresponding to a portion of the ligand-binding domain of the thyroid hormone receptor (tr) genes in several neotenic amphibians: the obligatory neotenic members of the family proteidea the mudpuppy necturus maculosus and proteus anguinus as well as two members of the facultative neotenic ambystoma genus: the axolotl ambystoma mexicanum and the tiger salamander ambystoma tigrinum. in addit ... | 1997 | 9169551 |
| urea and amphibian water economy. | accumulation of urea in the body fluids enables some amphibians to tolerate high ambient salinities (bufo viridis, xenopus laevis, rana cancrivora, ambystoma tigrinum, batrachoseps spp.) or to estivate in soil with low water potentials (scaphiopus spp.). these species are assumed not only to accumulate urea produced in the normal metabolism, but to synthesize urea in response to water shortage. re-examination of the data did not support the view of an osmoregulatory urea synthesis. increased ure ... | 1997 | 9172374 |
| the electrogenic na/hco3 cotransporter. | the electrogenic na/hco3 cotransporter (symporter) is the major hco3- transporter of the renal proximal tubule (pit), located at the basolateral membrane (blm), and also plays a noteworthy role in na+ reabsorption. hco3 transporters are important for regulation of intracellular ph (phi) in most cells and also thereby regulate blood ph. this electrogenic na/hco3 cotransporter was first discovered using perfused ambystoma tigrinum (salamander) renal, proximal tubules. this novel cotransporter medi ... | 1997 | 9261985 |
| kinematics of feeding in bluegill sunfish: is there a general distinction between aquatic capture and transport behaviors? | despite numerous studies of food transport in terrestrial vertebrates, little is known about this aspect of the feeding repertoire in aquatic vertebrates. previous work had predicted that the kinematics of aquatic prey capture by suction feeding should be similar to those of prey transport. however, recent analyses of aquatic prey capture and transport in the tiger salamander ambystoma tigrinum have contradicted this hypothesis, and document numerous differences between these two behaviors. in t ... | 1995 | 9318463 |
| immunocytochemical localization of gamma-aminobutyric acid plasma membrane transporters in the tiger salamander retina. | gamma-aminobutyric acid (gaba) plasma membrane transporters (gats) play an important role in regulating gaba neurotransmission in the nervous system. the distribution of two gats, gat 1 and gat 3, in salamander retina was investigated by using affinity-purified polyclonal antisera directed to the predicted c-terminals of rat gat 1 and rat gat 3. gat 1-immunoreactivity (-ir) was found in type ib and iib orthotopic bipolar cells (bcs) located in the distal and middle of the inner nuclear layer (in ... | 1997 | 9390763 |
| action potentials are required for the lateral transmission of glycinergic transient inhibition in the amphibian retina. | transient lateral inhibition (tli), the suppression of responses of a ganglion cell to light stimuli in the receptive field center by changes in illumination in the receptive field surround, was studied in light-adapted mud puppy and tiger salamander retinas using both eyecup and retinal slice preparations. in the eyecup, tli was measured in on-off ganglion cells as the ability of rotating, concentric windmill patterns of 500-1200 micron inner diameter to suppress the response to a small spot st ... | 1998 | 9482814 |
| cloning and functional expression of rnbc, an electrogenic na(+)-hco3- cotransporter from rat kidney. | we have recently cloned the renal electrogenic na(+)-bicarbonate contransporter of the salamander ambystoma tigrinum (anbc) (m. f. romero, m. a. hediger, e. l. boulpaep, and w. f. boron. faseb j. 10: 89, 1996; and nature 387: 409-413, 1997). here we report the cloning of a mammalian homolog of anbc, named rnbc for rat na(+)-bicarbonate cotransporter. nbc constitutes the major route for hco3- reabsorption and assists in na+ reabsorption across the basolateral membrane of the renal proximal tubule ... | 1998 | 9486238 |
| spectral and polarization sensitivity of photocurrents of amphibian rods in the visible and ultraviolet. | photocurrents from isolated rods of adults and sub-adults of three species of amphibians, rana pipiens, ambystoma tigrinum, and xenopus laevis, were measured with suction pipette electrodes. the intensity for a half-maximal response was 0.91+/-0.48 photons microm(-2) flash(-1) (mean +/- s.d., 10-ms flashes) for rana, 0.92+/-0.44 for ambystoma, and 6.14+/-1.33 for xenopus. the mean number of photoisomerizations at half-saturation was 22+/-12 for rana, 50+/-24 for ambystoma, and 221+/-48 for xenop ... | 1998 | 9605532 |
| age-related changes in the tiger salamander retina. | tiger salamanders have been used in visual science because of the large size of their cells and the ease of preparation and maintenance of in vitro retinal preparations. we have found that salamanders over 27 cm in length show a variety of visual abnormalities. compared to smaller animals (15-23 cm), large animals exhibited a decrease in visual responses determined by tests of the optomotor reflex. small animals responded correctly an average of 84.5% of the time in visual testing at three light ... | 1998 | 9631666 |
| pathology, isolation, and preliminary molecular characterization of a novel iridovirus from tiger salamanders in saskatchewan. | all iridovirus was confirmed to be the cause of an epizootic in larval and adult tiger salamanders (ambystoma tigrinum diaboli) from four separate ponds in southern saskatchewan (canada) during the summer of 1997. this organism also is suspected, based on electron microscopic findings, to be the cause of mortality of larval tiger salamanders in a pond over 200 km to the north during the same year. salamanders developed a generalized viremia which resulted in various lesions including: necrotizin ... | 1999 | 10479075 |
| cannabinoid cb1 receptors and ligands in vertebrate retina: localization and function of an endogenous signaling system. | cb1, a cannabinoid receptor enriched in neuronal tissue, was found in high concentration in retinas of rhesus monkey, mouse, rat, chick, goldfish, and tiger salamander by using a subtype-specific polyclonal antibody. immunolabeling was detected in the two synaptic layers of the retina, the inner and outer plexiform layers, of all six species examined. in the outer plexiform layer, cb1 was located in and/or on cone pedicles and rod spherules. labeling was detected in some amacrine cells of all sp ... | 1999 | 10588745 |
| extracellular hco(3)(-) dependence of electrogenic na/hco(3) cotransporters cloned from salamander and rat kidney. | we studied the extracellular [hcoabstract (3) (-)] dependence of two renal clones of the electrogenic na/hco(3) cotransporter (nbc) heterologously expressed in xenopus oocytes. we used microelectrodes to measure the change in membrane potential (deltav(m)) elicited by the nbc cloned from the kidney of the salamander ambystoma tigrinum (aknbc) and by the nbc cloned from the kidney of rat (rknbc). we used a two-electrode voltage clamp to measure the change in current (deltai) elicited by rknbc. br ... | 2000 | 10779312 |
| suppressive actions of betaxolol on ionic currents in retinal ganglion cells may explain its neuroprotective effects. | betaxolol, a beta 1-selective adrenoceptor antagonist, is widely used in the treatment of glaucoma. in addition to its ocular hypotensive effects, betaxolol has been suggested to act as a retinal neuroprotective agent (osborne et al., 1997). to investigate possible mechanisms underlying the neuroprotective effects, we tested the actions of betaxolol on ion channels and calcium signaling in isolated retinal ganglion cells. betaxolol (50 microm) reduced by about 20% the high-voltage-activated (hva ... | 2000 | 10870519 |
| cloning and functional characterization of salamander rod and cone arrestins. | to clone, localize, and determine functional binding characteristics of rod and cone arrestins from the retina of the tiger salamander (ambystoma tigrinum). | 2000 | 10937552 |
| pharmacological adrenalectomy with mitotane. | the potential of mitotane (ortho, para'-ddd, commonly used to treat adrenal carcinomas in humans and dogs) was investigated as an alternative to surgical adrenalectomy in birds, salamanders, and lizards. house sparrows (passer domesticus) were injected twice daily with vehicle or one of two doses of mitotane (225 or 450 mg/kg), and basal and stress-induced levels of corticosterone (cort) were measured 3 and 5 days after injections. mitotane reduced basal cort levels to nondetectable and abolishe ... | 2000 | 11042008 |
| immunoelectron microscopic localization of the electrogenic na/hco(3) cotransporter in rat and ambystoma kidney. | immunofluorescence analysis has revealed that electrogenic na(+)/hco(3)(-) (nbc1) is expressed in the proximal tubule of rat kidney and in the proximal and distal tubules of the salamander ambystoma: tigrinum kidney. the present study was undertaken to define the detailed subcellular localization of the nbc1 in rat and ambystoma: kidney using high-resolution immunoelectron microscopy. for this purpose, two rabbit polyclonal antibodies raised against amino acids 928 to 1035 and amino acids 1021 t ... | 2000 | 11095641 |
| salamander uv cone pigment: sequence, expression, and spectral properties. | the visual pigment from the ultraviolet (uv) cone photoreceptor of the tiger salamander has been cloned, expressed, and characterized. the cdna contains a full-length open reading frame encoding 347 amino acids. the phylogenetic analysis indicates that the highest sequence homology is to the visual pigments in the s group. the uv opsin was tagged at the carboxy-terminus with the sequence for the 1d4 epitope. this fusion opsin was expressed in cos-1 cells, regenerated with 11-cis retinal (a1) and ... | 2001 | 11497415 |
| transmission of the ambystoma tigrinum virus to alternative hosts. | ambystoma tigrinum virus (atv) is a lethal virus originally isolated from sonora tiger salamanders ambystoma tigrinum stebbinsi in the san rafael valley in southern arizona. usa. atv is implicated in several salamander epizootics. we attempted to transmit atv experimentally to fish and amphibians by injection, water bath exposure, or feeding to test whether atv can cause clinical signs of infection or be recovered from exposed individuals that do not show clinical signs. cell culture and polymer ... | 2001 | 11710549 |
| adaptation to temporal contrast in primate and salamander retina. | visual adaptation to temporal contrast (intensity modulation of a spatially uniform, randomly flickering stimulus) was examined in simultaneously recorded ensembles of retinal ganglion cells (rgcs) in tiger salamander and macaque monkey retina. slow contrast adaptation similar to that recently discovered in salamander and rabbit retina was observed in monkey retina. a novel method was developed to quantify the effect of temporal contrast on steady-state sensitivity and kinetics of light response ... | 2001 | 11739598 |
| membrane current of retinal rods of caudiverbera caudiverbera (amphibia: leptodactylidae): dark noise, spectral and absolute light sensitivity. | we investigated the photocurrents from isolated rods of the south american anuran, caudiverbera caudiverbera. rod outer segments were on average 66.4 +/- 11.2 microm (mean +/- s.d., n = 104) in length and 6.6 +/- 0.9 microm (mean +/- s.d.) in diameter: 40 +/- 22 photoisomerizations (mean +/- s.d., range 10-99, n = 16) were required for eliciting a half-saturating photocurrent response. the time-to-peak was 911 +/- 217 ms (mean +/- s.d., n = 14, 20 degrees c) in the linear range of the response a ... | 2001 | 11829312 |
| pharmacological characterization of p2y receptor subtypes on isolated tiger salamander müller cells. | müller cells express a variety of neurotransmitter receptors that permit them to "sense" the extracellular environment within the retina. we have used a battery of agonists and antagonists to characterize the purinergic receptor subtypes expressed on isolated tiger salamander müller cells. changes in intracellular calcium ion concentration ([ca(2+)](i)) in müller cells were measured using the ca(2+) indicator dye fura-2 and digital imaging microscopy. atp, 2-methylthio-atp, 2-methylthio-adp, adp ... | 2003 | 12655599 |
| evidence for multiple pleistocene refugia in the postglacial expansion of the eastern tiger salamander, ambystoma tigrinum tigrinum. | pleistocene glaciations were important determinants of historical migration and, hence, current levels of genetic diversity within and among populations. in many cases, these historical migrations led to the existence of disjunct populations of plants and animals. however, the origin and timing of arrival of these disjunct populations is often debated. in the current study, we identify potential refugia and estimate the timing of vicariance events of the eastern tiger salamander, ambystoma tigri ... | 2003 | 12683533 |
| cannabinoid receptor activation differentially modulates ion channels in photoreceptors of the tiger salamander. | cannabinoid cb1 receptors have been detected in retinas of numerous species, with prominent labeling in photoreceptor terminals of the chick and monkey. cb1 labeling is well-conserved across species, suggesting that cb1 receptors might also be present in photoreceptors of the tiger salamander. synaptic transmission in vertebrate photoreceptors is mediated by l-type calcium currents-currents that are modulated by cb1 receptors in bipolar cells of the tiger salamander. presence of cb1 receptors in ... | 2003 | 12740409 |
| a novel xenopus sws2, p434 visual pigment: structure, cellular location, and spectral analyses. | the purpose of this study was to clone and characterize the green rod pigment in xenopus laevis. | 2003 | 12764253 |
| ph modulates the vestibular afferent discharge and its response to excitatory amino acids. | in the isolated inner ear of the axolotl (ambystoma tigrinum) acid ph decreased and basic ph increased the resting and mechanically evoked spike discharge of semicircular canal afferent neurons. variations in ph also modified the afferent neuron response to n-methyl-d-aspartic acid (nmda) acid and to (+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (ampa). responses to both excitatory amino acid agonists increased at ph 7.8 (41% and 22%, respectively) and decreased by perfusion of ... | 2003 | 12876466 |
| [persistence of leptospira icterohaemorrhagiae in the axolotl (ambystoma tigrinum)]. | | 1963 | 14190217 |
| diagnostic and molecular evaluation of three iridovirus-associated salamander mortality events. | in 1998 viruses were isolated from tiger salamander larvae (ambystoma tigrinum diaboli and a. tigrinum melanostictum) involved in north dakota and utah (usa) mortality events and spotted salamander (a. maculatum) larvae in a third event in maine (usa). although sympatric caudates and anurans were present at all three sites only ambystomid larvae appeared to be affected. mortality at the north dakota site was in the thousands while at the utah and maine sites mortality was in the hundreds. sick l ... | 2003 | 14567216 |
| genomic sequence of a ranavirus (family iridoviridae) associated with salamander mortalities in north america. | disease is among the suspected causes of amphibian population declines, and an iridovirus and a chytrid fungus are the primary pathogens associated with amphibian mortalities. ambystoma tigrinum virus (atv) and a closely related strain, regina ranavirus (rrv), are implicated in salamander die-offs in arizona and canada, respectively. we report the complete sequence of the atv genome and partial sequence of the rrv genome. sequence analysis of the atv/rrv genomes showed marked similarity to other ... | 2003 | 14599794 |
| environment-dependent admixture dynamics in a tiger salamander hybrid zone. | after an estimated five million years of independent evolution, the barred tiger salamander (ambystoma tigrinum mavortium) was introduced by bait dealers into the native range of the california tiger salamander (a. californiense). hybridization and backcrossing have been occurring in central california for 50-60 years, or an estimated 15-30 generations. we studied genetic and ecological factors influencing admixture of these two divergent gene pools by analyzing frequencies of hybrid genotypes i ... | 2004 | 15266977 |
| from biomedicine to natural history research: est resources for ambystomatid salamanders. | establishing genomic resources for closely related species will provide comparative insights that are crucial for understanding diversity and variability at multiple levels of biological organization. we developed ests for mexican axolotl (ambystoma mexicanum) and eastern tiger salamander (a. tigrinum tigrinum), species with deep and diverse research histories. | 2004 | 15310388 |
| a dna-based assay identifies batrachochytrium dendrobatidis in amphibians. | chytridiomycosis caused by batrachochytrium dendrobatidis (chytridiomycota) has been implicated in declines of amphibian populations on four continents. we have developed a sensitive and specific polymerase chain reaction-based assay to detect this pathogen. we isolated b. dendrobatidis from captive and wild amphibians collected across north america and sequenced the internal transcribed spacer regions of the rdna cassette of multiple isolates. we identified two primers (bd1a and bd2a) that are ... | 2004 | 15465708 |
| a dark and constitutively active mutant of the tiger salamander uv pigment. | a triple mutant (f86l/t93p/s118t; bovine rhodopsin numbering) of the tiger salamander uv cone pigment appears to be trapped in an open conformation that is metarhodopsin-ii-like. the pigment is able to activate transducin in the dark, and the ligand-free apoprotein is also able to activate transducin constitutively. the pigment permits protons and chloride ions from solution access to the active site as it displays a ph- and nacl-dependent absorption spectrum not observed with the wild-type pigm ... | 2005 | 15641808 |
| evidence for emergence of an amphibian iridoviral disease because of human-enhanced spread. | our understanding of origins and spread of emerging infectious diseases has increased dramatically because of recent applications of phylogenetic theory. iridoviruses are emerging pathogens that cause global amphibian epizootics, including tiger salamander (ambystoma tigrinum) die-offs throughout western north america. to explain phylogeographical relationships and potential causes for emergence of western north american salamander iridovirus strains, we sequenced major capsid protein and dna me ... | 2005 | 15643965 |
| influence of temperature on ranavirus infection in larval salamanders ambystoma tigrinum. | temperature strongly influenced percent mortality and time to death of salamanders exposed to the ambystoma tigrinum virus (iridovirus) (atv). most salamanders survived when exposed at 26 degrees c, whereas all died at 18 degrees c and nearly all died at 10 degrees c. some asymptomatic salamanders that survived 60 d at 10 or 26 degrees c were found to be carrying virus. polymerase chain reaction (pcr) confirmed the presence of virus in atv-exposed salamanders but was found to be less sensitive t ... | 2005 | 15819423 |
| dose and host characteristics influence virulence of ranavirus infections. | parasites play a prominent role in the ecology, evolution, and more recently, conservation of many organisms. for example, emerging infectious diseases, including a group of lethal ranaviruses, are associated with the declines and extinctions of amphibians around the world. an increasingly important basic and applied question is: what controls parasite virulence? we used a dose-response experiment with three laboratory-bred clutches of tiger salamander larvae (ambystoma tigrinum) to test how the ... | 2005 | 15891818 |
| dietary k+ regulates apical membrane expression of maxi-k channels in rabbit cortical collecting duct. | the cortical collecting duct (ccd) is a final site for regulation of k(+) homeostasis. ccd k(+) secretion is determined by the electrochemical gradient and apical permeability to k(+). conducting secretory k(+) (sk/romk) and maxi-k channels are present in the apical membrane of the ccd, the former in principal cells and the latter in both principal and intercalated cells. whereas sk channels mediate baseline k(+) secretion, maxi-k channels appear to participate in flow-stimulated k(+) secretion. ... | 2005 | 15914780 |
| identification of a non-mammalian leptin-like gene: characterization and expression in the tiger salamander (ambystoma tigrinum). | leptin is well established as a multifunctional cytokine in mammals. however, little is known about the evolution of the leptin gene in other vertebrates. a recently published set of ests from the tiger salamander (ambystoma tigrinum) contains a sequence sharing 56% nucleotide sequence identity with the human leptin cdna. to confirm that the est is naturally expressed in the salamander, a 409bp cdna was amplified by rt-pcr of salamander testis and stomach mrnas. the coding sequence of the cdna i ... | 2006 | 16480984 |
| electrical coupling, receptive fields, and relative rod/cone inputs of horizontal cells in the tiger salamander retina. | light responses, dendritic/axonal morphology, receptive field diameters, patterns of dye coupling, and relative rod/cone inputs of various types of horizontal cells (hcs) were studied using intracellular recording and lucifer yellow/neurobiotin dye injection methods in the flatmount tiger salamander retina. three physiologically and morphologically distinct types of hc entities were identified. 1) the a-type hcs are somas that do not bear axons, with average (+/-se) soma diameters of 20.01 +/- 0 ... | 2006 | 16998920 |
| first case of ranavirus-associated morbidity and mortality in natural populations of the south american frog atelognathus patagonicus. | atelognathus patagonicus is an endangered leptodactylid frog endemic to a small region in and around laguna blanca national park in northern patagonia, argentina. all of the lakes and small ponds of the region (except laguna blanca itself) contain a. patagonicus and in all but one of these lakes the species shows clinical signs of a previously undiagnosed disease, the characteristics of which suggested a ranavirus. we collected symptomatic and asymptomatic a. patagonicus frogs and tadpoles from ... | 2006 | 17067077 |
| atrazine increases ranavirus susceptibility in the tiger salamander, ambystoma tigrinum. | pathogenic diseases and environmental contaminants are two of the leading hypotheses for global amphibian declines, yet few studies have examined the influence of contaminants on disease susceptibility. in this study, we examined effects of ecologically relevant doses of atrazine (0, 1.6, 16, and 160 microg/l), sodium nitrate (0, 6.8, 68 mg/l), and their interactions on susceptibility of four laboratory-bred tiger salamander families to ambystoma tigrinum virus (atv), a pathogen implicated in gl ... | 2006 | 17205907 |
| adenosine inhibits voltage-dependent ca2+ influx in cone photoreceptor terminals of the tiger salamander retina. | endogenous adenosine has already been shown to inhibit transmitter release from the rod synapse by suppressing ca(2+) influx through voltage-gated ca(2+) channels. however, it is not clear how adenosine modulates the cone synapse. cone photoreceptors, like rod photoreceptors, also possess l-type ca(2+) channels that regulate the release of l-glutamate. to assess the impact of adenosine on ca(2+) influx though voltage-gated ca(2+) channels in cone terminals, whole-cell perforated-patch clamp reco ... | 2007 | 17304584 |
| molecular characterization of mhc class ii in a nonmodel anuran species, the fire-bellied toad bombina bombina. | while the anuran xenopus comprises one of the best characterized nonmammalian taxa regarding the major histocompatibility complex (mhc), the organization of this gene complex has never been studied in other anurans, and information on amphibian mhc (other than xenopus) is generally very scarce. here, we describe the characterization of the first mhc class ii b cdna sequences from a nonmodel anuran species, the european fire-bellied toad (bombina bombina). we isolated two transcript sequences dif ... | 2007 | 17406862 |
| susceptibility of the endangered california tiger salamander, ambystoma californiense, to ranavirus infection. | emerging infectious diseases are implicated in the declines and extinctions of amphibians worldwide. ranaviruses in the family iridoviridae are a global concern and have caused amphibian die-offs in wild populations in north america, europe, south america, and in commercial populations in asia and south america. the movement of amphibians for bait, food, pets, and research provides a route for the introduction of ranaviruses into naive and potentially endangered species. in this report, we demon ... | 2007 | 17495315 |
| sensitivity of a diagnostic test for amphibian ranavirus varies with sampling protocol. | field samples are commonly used to estimate disease prevalence in wild populations. our confidence in these estimates requires understanding the sensitivity and specificity of the diagnostic tests. we assessed the sensitivity of the most commonly used diagnostic tests for amphibian ranavirus by infecting salamanders (ambystoma tigrinum; amphibia, caudata) with ambystoma tigrinum virus (atv) and then sampling euthanized animals (whole animal) and noneuthanized animals (tail clip) at five time int ... | 2007 | 17699094 |
| phylogenetic concordance analysis shows an emerging pathogen is novel and endemic. | distinguishing whether pathogens are novel or endemic is critical for controlling emerging infectious diseases, an increasing threat to wildlife and human health. to test the endemic vs. novel pathogen hypothesis, we present a unique analysis of intraspecific host-pathogen phylogenetic concordance of tiger salamanders and an emerging ranavirus throughout western north america. there is significant non-concordance of host and virus gene trees, suggesting pathogen novelty. however, non-concordance ... | 2007 | 17850337 |
| transmission dynamics of the amphibian ranavirus ambystoma tigrinum virus. | transmission is central to pathogen fitness and strongly influences the impact of pathogens on host populations. particularly important to transmission dynamics is the distinction between direct transmission requiring close physical contact (e.g. bumping, fighting, or coughing) and indirect transmission from environmental sources such as contaminated substrates. we present data from 4 experiments addressing the form, routes, and timing of transmission of ambystoma tigrinum virus (atv) among tige ... | 2007 | 17972749 |
| habitat fragmentation as a result of biotic and abiotic factors controls pathogen transmission throughout a host population. | 1. the hypothesis that habitat fragmentation (biotic or abiotic) alters the transmission of disease within a population is explored using field data from a well-studied amphibian-pathogen system. 2. we used the ambystoma tigrinum-a. tigrinum virus (atv) model system to show how habitat fragmentation as a result of emergent vegetation and habitat management affects disease transmission dynamics in ponds across a landscape. 3. we quantified variation in atv infection over time and across the lands ... | 2008 | 18005032 |
| retinal bipolar cells: temporal filtering of signals from cone photoreceptors. | the temporal dynamics of the response of neurons in the outer retina were investigated by intracellular recording from cones, bipolar, and horizontal cells in the intact, light-adapted retina of the tiger salamander (ambystoma tigrinum), with special emphasis on comparing the two major classes of bipolars cells, the on depolarizing bipolars (bd) and the off hyperpolarizing bipolars (bh). transfer functions were computed from impulse responses evoked by a brief light flash on a steady background ... | 2007 | 18093365 |
| salamander blue-sensitive cones lost during metamorphosis. | the tiger salamander lives in shallow water with bright light in the aquatic phase, and in dim tunnels or caves in the terrestrial phase. in the aquatic phase, there are five types of photoreceptors--two types of rods and three types of cones. our previous studies showed that the green rods and blue-sensitive cones contain the same visual pigment and have the same absorbance spectra; however, the green rods have a larger photon-catch area and thus have higher light sensitivity than the blue-sens ... | 2008 | 18331398 |
| antimicrobial peptide defenses in the salamander, ambystoma tigrinum, against emerging amphibian pathogens. | skin peptides were collected from living ambystoma tigrinum larvae and adults and tested against two emerging pathogens, batrachochytrium dendrobatidis and the ambystoma tigrinum virus (atv), as well as bacteria isolated from a. tigrinum. natural mixtures of skin peptides were found to inhibit growth of b. dendrobatidis, staphylococcus aureus, and klebsiella sp., but activity against atv was unpredictable. skin peptides collected from salamanders held at three environmentally relevant temperatur ... | 2008 | 18436656 |
| geographically variable selection in ambystoma tigrinum virus (iridoviridae) throughout the western usa. | we investigated spatially variable selection in ambystoma tigrinum virus (atv) which causes frequent and geographically widespread epizootics of the tiger salamander, ambystoma tigrinum. to test for evidence of selection, we sequenced several coding and noncoding regions from virus strains isolated from epizootics throughout western north america. three of the sequenced regions contained homologues for genes putatively involved in host immune evasion and virulence: eif-2alpha, caspase activation ... | 2008 | 18444995 |
| amphibian commerce as a likely source of pathogen pollution. | the commercial trade of wildlife occurs on a global scale. in addition to removing animals from their native populations, this trade may lead to the release and subsequent introduction of nonindigenous species and the pathogens they carry. emerging infectious diseases, such as chytridiomycosis caused by the chytrid fungus batrachochytrium dendrobatidis (bd), and ranaviral disease have spread with global trade in amphibians and are linked to amphibian declines and die-offs worldwide, which sugges ... | 2008 | 18717688 |
| transcriptional response of mexican axolotls to ambystoma tigrinum virus (atv) infection. | very little is known about the immunological responses of amphibians to pathogens that are causing global population declines. we used a custom microarray gene chip to characterize gene expression responses of axolotls (ambystoma mexicanum) to an emerging viral pathogen, ambystoma tigrinum virus (atv). | 2008 | 18937860 |
| from retinal circuitry to eye diseases--in memory of henk spekreijse. | this article summarizes our recent works on stratum-by-stratum structure-function rules for synaptic contacts between retinal bipolar cells and third-order retinal neurons in the inner plexiform layer. these rules were derived from large-scale voltage clamp recordings of various types of bipolar cells in the tiger salamander retina, and they appear applicable to bipolar cells in the mouse and other mammalian species. this review also gives a brief account of how we used pathway-specific knockout ... | 2009 | 18948133 |
| combined effects of atrazine and chlorpyrifos on susceptibility of the tiger salamander to ambystoma tigrinum virus. | several hypotheses have been examined as potential causes of global amphibian declines, including emerging infectious diseases and environmental contaminants. although these factors are typically studied separately, animals are generally exposed to both stressors simultaneously. we examined the effects of the herbicide atrazine and the insecticide chlorpyrifos on the susceptibility of tiger salamander larvae, ambystoma tigrinum, to a viral pathogen, ambystoma tigrinum virus (atv). environmentall ... | 2009 | 19415385 |
| complete sequence determination of a novel reptile iridovirus isolated from soft-shelled turtle and evolutionary analysis of iridoviridae. | soft-shelled turtle iridovirus (stiv) is the causative agent of severe systemic diseases in cultured soft-shelled turtles (trionyx sinensis). to our knowledge, the only molecular information available on stiv mainly concerns the highly conserved stiv major capsid protein. the complete sequence of the stiv genome is not yet available. therefore, determining the genome sequence of stiv and providing a detailed bioinformatic analysis of its genome content and evolution status will facilitate furthe ... | 2009 | 19439104 |
| spatial and temporal patterns of ambystoma tigrinum virus (atv) prevalence in tiger salamanders ambystoma tigrinum nebulosum. | amphibian ranaviruses have been documented as causes of mass mortality in amphibian populations throughout the world. the temporal and spatial dynamics of ranavirus infections when epidemics are not apparent remains unclear. to address this question, we collected tissue samples from 2003 to 2006 in 4 geographically separated tiger salamander ambystoma tigrinum nebulosum host populations on the kaibab plateau in northern arizona. we tested for ambystoma tigrinum virus (atv), a lethal ranavirus of ... | 2009 | 19593927 |
| evidence for urea-induced hypometabolism in isolated organs of dormant ectotherms. | many organisms endure extended periods of dormancy by depressing their metabolism, which effectively prolongs the use of their endogenous energy stores. though the mechanisms of hypometabolism are varied and incompletely understood, recent work suggests that urea accumulation in autumn and early winter contributes to reduced metabolism of hibernating wood frogs (rana sylvatica). urea accumulation during dormancy is a widespread phenomenon, and it has long been presumed that numerous species from ... | 2010 | 19739087 |
| the antagonism between thyroid and parathyroid glands. | from the facts stated in this paper it is evident that the thymus gland of mammals contains a substance which is capable of producing tetany when fed to the larvae of certain species of salamanders (ambystoma opacum and ambystoma maculatum). as long as the larvae have not developed their own thymus glands, they are able, by means of some mechanism, to counterbalance the tetanic action of the thymus substance introduced in their food. when, however, the secretion from their own thymus glands is a ... | 1918 | 19871724 |
| experimental production of gigantism by feeding the anterior lobe of the hypophysis. | 1. metamorphosed salamanders of the species ambystoma opacum and ambystoma tigrinum were fed on a pure diet of the anterior lobe of the hypophysis of cattle; the controls were fed on an abundant diet of earthworms. 2. the rate of growth of the animals fed on the anterior lobe of the hypophysis was greatly increased over the rate of growth of normal animals. 3. growth of the animals fed on anterior lobe did not cease after they had reached the normal "maximum" size of the species, and experimenta ... | 1921 | 19871871 |