Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| effects of temperature transients on gas exchange and acid-base status of turtles. | pulmonary ventilation (ve), o2 consumption (vo2), and co2 production (vco2) were measured continuously on each of 10 turtles, pseudemys scripta elegans, at 20 degrees c, during and for 1 h after heating to 30 degrees c and during and for 1 h after cooling to 20 degrees c. in seven of the animals, arterial blood was sampled at the three temperature plateaus. ventilatory ratios (ve/vo2 and ve/vco2) and metabolic rate adjusted promptly to temperature change, stabilizing at values similar to those o ... | 1976 | 5899 |
| non-pulmonary co2 loss during diving in the turtle, pseudemys scripta elegans. | 1976 | 9231 | |
| intracellular ph in cold-blooded vertebrates as a function of body temperature. | intracellular ph (phi) was measured in vivo in tissue of frogs (rana catesbeiana) and turtles (pseudemys scripta) using the dmo technique. animals were permitted 3-8 days to come to a new steady-state body temperature (tb) which ranged 5-32 degrees c. least squares regression equation for phi data are: frog blood, 8.184-0.0206 tb; frog striated muscle, 7.275-0.0152 tb; turtle blood, 8.092-0.0207tb; turtle muscle, 7.421-0.0186 tb; turtle heart, 7.452-0.0122 tb; turtle liver, 7.753-0.0233 tb; turt ... | 1976 | 10614 |
| model studies of intracellular acid-base temperature responses in ectotherms. | measurements of intracellular ph (phi) in air-breathing ectotherms have only been made in the steady state; these phi indicate that protein charge state, measured as alpha imidazole (alphaim), the fractional dissociation of protein histidine imidazole groups, is preserved when ectotherm tissues change temperature in vivo, with related changes in phi and pco2. in partial answer to the question of how such tissues are able to avoid disrupting transients to functions sensitive to protein charge sta ... | 1976 | 10615 |
| properties of blood oxygen transport in the turtle pseudemys scripta and the tortoise testudo graeca: effects of temperature, co2 and ph. | properties of oxygen-haemoglobin binding have been investigated in the aquatic turtle psuedemys scripta and the terrestrial tortoise testudo graeca. haematocrit (30-35%) and haemoglobin concentration (12-14 g/100 ml blood) were similar in both species. p50 at physiological levels of pco2 (20-25 mm hg) was 21 mm hg in pseudemys, compared with 23 mm hg in testudo. the bohr shift of the blood of both the turtle and the tortoise was almost identical at -0.28. the heat of oxygenation, deltah, reflect ... | 1977 | 21433 |
| bicarbonate ion transport: a mechanism for the acidification of urine in the turtle. | the uricotelic turtle pseudemys scripta acidifies the urine to a ph as low as 4 in the urinary bladder. data in this report show that the mechanism of acidification in this bladder is the transport of bicarbonate ion from lumen to serosa, and that the temperature to which the turtles are adapted prior to the in vitro experiment largely determines the direction of the transmural carbon dioxide gradient observed. this temperature effect also serves to reconcile apparently disparate data that were ... | 1978 | 24894 |
| staining of the dorsal root primary afferent fibers by anterograde movement of horseradish peroxidase and retrograde labelling of motoneurons and preganglionic autonomic cells in the turtle spinal cord. | the enzyme horseradish peroxidase (hrp) has been applied to the proximal stumps of severed thoracic and lumbar dorsal roots in the turtles pseudemys scripta elegans and testudo hermanni. the results obtained confirm the distribution pattern observed with anterograde degeneration techniques. primary afferent terminal structures, however, could be demonstrated in more detail. commonly, ventral roots were also more or less damaged which resulted in the presence of retrogradely labeled motoneurons a ... | 1999 | 93720 |
| histochemical distribution of acid mucopolysaccharides in the tongue of reptiles. i. chelonia (pseudemys scripta clark). | 2002 | 128315 | |
| effect of starvation on fructose diphosphatase, glucose-6-phosphatase and phosphoglucomutase activities in organs of pseudemys (chrysemys) scripta elegans. | 1975 | 164319 | |
| signal transmission from red cones to horizontal cells in the turtle retina. | 1. intracellular recordings were made from l-type horizontal cells in the retina of the turtle pseudemys scripta elegans. the responses were evoked by 500 msec pulses of 'white' light. 2. l-type horizontal cells were classified as either, 'small receptive field' s.r.f. or 'large receptive field' l.r.f. based upon (1) receptive field size and (2) kinetics of responses to test flashes covering small and big spots. 3. constant illumination of the entire receptive field, with any intensity studied, ... | 1982 | 220415 |
| interactions between tectal radial cells in the red-eared turtle, pseudemys scripta elegans: an analysis of tectal modules. | the optic tectum is a major subdivision of the visual system in reptiles. previous studies have characterized the laminar pattern, the neuronal populations, and the afferent and efferent connections of the optic tectum in a variety of reptiles. however, little is known about the interactions that occur between neurons within the tectum. this study describes two kinds of interactions that occur between one major class of neurons, the radial cells, in the optic tectum of pseudemys using nissl, gol ... | 1979 | 228046 |
| the effects of induced cold torpor and time of year on blood coagulation in pseudemys scripta elegans and chrysemys picta belli. | 1975 | 236129 | |
| respiratory control and co2 conductance: temperature effects in a turtle and a frog. | the respiratory control systems of the predominantly lung-breathing turtle. pseudemys scripta, and the bimodal breathing frog, rana catesbeiana, are compared. at constant temperature, control is effected in both species primarily by pulmonary ventilation, and appears to be similar in basic organization to the mammalian system. the skin co2 exchange of the frog is largely passive and apparently under little adaptive control. co2 exchange at different temperature is analyzed by means of the conduc ... | 1978 | 307794 |
| some comparative aspects of the organ distribution of superoxide dismutase activity in the freshwater turtle, pseudemys scripta elegans. | 1. superoxide dismutase activities in five tissues of the relatively anaerobic freshwater turtle were compared with sod activities in the same tissues of two mammalian species (mouse and rabbit) with a more usual pattern of dependence on o2 availability. 2. sod activities in brain, lung and skeletal muscle, but not liver or cardiac muscle, are significantly lower in the turtle. the turtle also shows differences in the pattern of relative sod activities in various tissues as compared to the two m ... | 1977 | 318271 |
| effects of sustained oxygen depletion on tissue pyruvate kinase activities in the freshwater turtle, pseudemys scripta elegans. | 1. the effect of sustained (48 hr) oxygen depletion on tissue (brain, heart, skeletal muscle) pyruvate kinase (pyki) activities was examined in the pond turtle (pseudemys scripta elegans). 2. pyki activities in skeletal muscle are significantly increased (from 322 +/- 84 to 450 +/- 95) following 48 hr of tissue hypoxia. pyki activities in brain may already be elevated under ambient conditions but do not change following prolonged submersion (334 +/- 75 vs 325 +/- 77). cardiac muscle pyki is actu ... | 1979 | 318413 |
| quantitative studies of retinal ganglion cells in a turtle, pseudemys scripta elegans. i. number and distribution of ganglion cells. | multiple pathways for the transmission of visual information from retina to brain have been described in reptiles, but little is known about their functional organization. these parallel channels begin at the retina, and we have therefore begun to study the functional organization of retinal ganglion cells in the turtle, pseudemys scripta elegans. this paper describes the numbers and distribution of cells in the ganglion cell layer. to develop criteria for the identification of ganglion cells, w ... | 1979 | 457929 |
| organization of nucleus rotundus, a tectofugal thalamic nucleus in turtles. i. nissl and golgi analyses. | this study consists of a detailed cytoarchitectonic and golgi analysis of a major tectofugal thalamic nucleus in the red-eared turtle, pseudemys scripta elegans. neurons in nucleus rotundus have a unimodal soma size distribution and a common dendritic branching pattern. they have long dendrites which undergo sparse, dichotomous branchings and contribute to dendritic fields that cover a third to half the dimensions of the nucleus. spicules, 1-2 mu long, and complex appendages, 5-20 mu long, are f ... | 1979 | 458858 |
| the mechanism of spinal control of reflex hind limb movements in the terrapin pseudemys scripta elegans [proceedings]. | 1979 | 490344 | |
| mirex residues in eggs and livers of two long-lived reptiles (chrysemys scripta and terrapene carolina) in mississippi, 1970-1977. | 1979 | 519044 | |
| the fine structure of the anterior median eminence in the turtle pseudemys scripta elegans (wied). | 1979 | 554565 | |
| the responses of amacrine cells to light and intracellularly applied currents. | 1. intracellular responses to light were recorded from amacrine cells in the retina of the turtle pseudemys scripta elegans. 2. the recorded responses were identified on the basis of physiological criteria reported previously (marchiafava, 1976). amacrine cells produced transient 'on' and 'off' depolarizing responses irrespective of the retinal area illuminated and of wavelength. 3. the transient depolarizing responses increased by enlarging the illuminated circle up to 120 micrometer in radius. ... | 1978 | 565815 |
| analysis of electrical noise in turtle cones. | 1. properties of the light-sensitive voltage noise in cones in the retina of the turtle, pseudemys scripta elegans, have been studied by intracellular recording.2. suppression of the noise by light was a function of the hyperpolarizing response of a cone but not of the size or pattern of illumination.3. power density spectra of the noise were fitted in many cones by the product of two lorentzians with characteristic time constants tau(1) and tau(2) averaging 40 and 7 msec respectively. the spect ... | 1977 | 592199 |
| myocardial inotrophy of co2 in water- and air-breathing vertebrates. | a negative-inotropic effect of co2 on myocardial contractility presumably occurs because increasing h+ concentration competes with ca2+ at cellular membranes and proteins. since air-breathing vertebrates have higher blood and tissue co2 concentration than water breathers the question was raised whether the cardiac cell has a modified sensitivity to co2 correlated with the evolutionary transition of vertebrates from water breathers to air breathers. the water-breathing fish, salmo gairdneri, and ... | 1978 | 629370 |
| effect of dry versus wet bowl environment on pet turtles. | recently hatched, certified salmonella-free, red-eared slider turtles (pseudemys scripta elegans) were obtained from a commercial breeder. half of the turtles were kept in a traditional wet-bowl environment, whereas the other half lived in individual dry-bowl environments, except for 30 minutes each day when they were immersed in water and were fed. both groups were fed commercial turtle food. during the 26 weeks of the study, individual weight and general observations were recorded for each tur ... | 1978 | 629431 |
| activation of latent salmonella and arizona organisms by dehydration of red-eared turtles, pseudemys scripta-elegans. | salmonella and arizona organisms could not be isolated from water samples, feces, and tissues of turtles prior to the experiment. after stressing, salmonella organisms were isolated from tissues of 7 of 27 stressed turtles and from only 1 of 12 unstressed turtles. arizona organisms were isolated from 9 of 36 stressed turtles whereas results for all 12 unstressed turtles were negative. | 1978 | 637401 |
| influence of intermittent breathing on ventricular depolarization patterns in chelonian reptiles. | 1. alterations between two quite distinct patterns of epicardial depolarization are associated with the normal occurrence of intermittent lung ventilation in both lightly anaesthetized and unrestrained, conscious turtles (pseudemys scripta) and tortoises (testudo graeca). 2. during apnoea depolarization sweeps from the left to the right over the ventricular surface at a conduction velocity of 0.15 m/sec. with the onset of lung ventilation the direction of depolarization propagation over the vent ... | 1978 | 671311 |
| membrane recycling in the cone cell endings of the turtle retina. | the ultrastructural effects of dark, light, and low temperature were investigated in the cone cell endings of the red-eared turtle (pseudemys scripta elegans). thin sections revealed that in dark-adapted retinas maintained at 22 degrees c, the neural processes which contact the cone cells at the invaginating synapses penetrated deeply into the photoreceptor endings. when dark-adapted retinas were illuminated for 1 h at 22 degrees c, the invaginating processes were apparently extruded from the sy ... | 1978 | 730768 |
| horizontal cells of the turtle retina. ii. analysis of interconnections between photoreceptor cells and horizontal cells by light microscopy. | criteria were established whereby the chief and accessory members of double cones, red-, green-, and blue-sensitive single cones, and rods could be distinguished from one another in 1-micrometer sections through the retinas of pseudemys scripta elegans and chelydra serpentina. criteria included the presence of absence of an oil droplet, the size, color, and radial position of the oil droplet, the size and shape of the inner and outer segments, and the shape orientation of the connection between ... | 1978 | 730848 |
| structure of anterior dorsal ventricular ridge in a turtle (pseudemys scripta elegans). | 1978 | 731705 | |
| helminth parasites of the red-eared turtle (pseudemys scripta elegans) in central arkansas. | 1978 | 739316 | |
| quantitative anatomy of the lungs of the red-eared turtle, pseudemys scripta elegans. | morphometric and sterological methods were employed to evaluate the anatomical gas-exchange potential of the lungs of the fresh-water turtle, pseudemys scripta elegans. the total lung volume and lung wet weight increase with the 1.4 power of body weight. right and left lungs are similar in size and shape, containing a tissue-free central lumen, which occupies 55 per cent of the maximally inflated lung. the remainder is parenchyma, composed of 90 per cent air and 10 per cent tissue, with an effec ... | 1978 | 741106 |
| vagal control of pulmonary vascular resistance in the turtle chrysemys scripta. | 1977 | 837291 | |
| visual cortex in a reptile, the turtle (pseudemys scripta and chrysemys picta). | 1977 | 884523 | |
| the effect of hypothalamic thermal stimulation on respiration in the turtle. | cumulative oxygen consumption (vo2) and oxygen consumption per unit time were measured for fresh water turtles (pseudemys scripta elegans) as hypothalamic stimulation was applied. stimulation was provided by means of a thermode at 9-2o c (cold), 27o c (sham), and 55-60 degrees c (hot). a statistically significant increase in mean cumulative oxygen consumption was noted for hot stimulation as compared to control value. a less dramatic but significant decrease in mean cumulative oxygen consumption ... | 1976 | 932666 |
| plasma amino acids in reptiles after feeding protein or amino acids and after injecting amino acids. | turtles (pseudemys scripta elegans) and alligators (alligator mississipiensis) were fed fish, casein, or free amino acid mixtures, or were injected with free amino acid mixtures, quantities in each case being equivalent to about 42 mmoles of amino acids/kg body weight. the experiments were designed to determine whether protein synthesis normally precedes catabolism of the amino acids absorbed from digesting food. both animals disposed of free or food-derived amino acids more rapidly than could b ... | 1976 | 939990 |
| a technique for intravenous injection in the red-eared turtle (pseudemys scripta elegans). | a technique is described for exposure and injection of the jugular vein in the red-eared turtle. satisfactory anaesthesia and muscular relaxation for this procedure was obtained by intramuscular injection of a mixture of chloral hydrate and sodium pentobarbital at a dose of 2.5 ml/kg bodyweight. induction time was 30-45 minutes. time for surgical procedure 30-45 minutes. recovery time 1-8 hours. | 1976 | 979135 |
| spatial properties of horizontal cell responses in the turtle retina. | 1. intracellular recordings were made from horizontal cells in the retina of the turtle pseudemys scripta elegans. spatial properties of the responses were determined using brief flashes of monochromatic light. 2. for a light stimulus in the form of a long narrow slit the peak response decayed approximately exponentially with displacement from the centred position. 3. with variation in the area of a centred circular patch, the peak response increased in a graded manner with stimulus area but was ... | 1976 | 1018237 |
| the relation between intercellular coupling and electrical noise in turtle photoreceptors. | 1. intracellular recordings from cones and rods in the retina of the turtle, pseudemys scripta elegans, revealed that in darkness the cell voltage fluctuated spontaneously about its mean level. the fluctuations were reduced during bright steady illmination of the cell often to a level close to that obtained with the electrode outside the cell where the noise did not change significantly during illumination. 2. the magnitude of the intrinsic dark noise (voltage variance in darkness minus voltage ... | 1976 | 1018249 |
| two new species of the genus caminacarus (acarina: cloacaridae) from turtles in louisiana. | caminacarus chrysemys sp. n. and caminacarus terrapenae sp. n. are described from the cloaca of chrysemys scripta elegans and terrapene carolina in louisiana. the former species is very similar to caminacarus deirochelys but differs in the form of the dorsal shield which has longer lateral elongations and the median dorsal elongation does not extend to the genital sclerite, structure of the anterodorsal wall of the gnathosomal base which is closed forming a ringlike apodeme, and structure of the ... | 1975 | 1117354 |
| eimeria pseudemydis lainson, 1968, from the red-eared turtle, pseudemys scripta elegans, in arkansas. | 2005 | 1142563 | |
| properties of centre-hyperpolarizing, red-sensitive bipolar cells in the turtle retina. | 1. responses of centre-hyperpolarizing, red-sensitive bipolar cells were studied by intracellular recording in the retina of the turtle, pseudemys scripta elegans. the identity of these cells was confirmed by procion yellow marking. 2. circles of light produced hyperpolarizing waves that were graded with intensity and could exceed -30mv in amplitude. the operating intensity range was similar to that of turtle cones. 3. flashes in the form of an annulus evoked graded depolarizations which could b ... | 2005 | 1151785 |
| the connections and laminar organization ofthe optic tectum in a reptile (lguana iguana). | the goals of this study were: (1) to describe the total pattern of projections from the optic tectum of iguana iguana and pseudemys scripta; and (2) to describe the contributions of particular lamina of the iguana's optic tectum to this total pattern. lesions were made in the optic tectum of the iguana which damaged either all or only certain tectal laminae and, for comparison with the iguana, lesions in the turtle's optic tectum were made which involved all laminae. the anterograde degeneration ... | 1975 | 1176645 |
| a quantitative analysis of ventilation tachycardia and its control in two chelonians, pseudemys scripta and testudo graeca. | 1. in both the turtle, pseudemys scripta, and the tortoise, testudo graeca, lung ventilation is closely accompanied by a tachycardia of predictable magnitude and duration. 2. efferent vagal activity progressively decreases as heart rate increases with the onset of lung ventilation. atropine decreases heart rate during apnoea to those levels observed during prolonged breathing series when the development, duration or magnitude of ventilation tachycardia. it is thus concluded that heart rate chang ... | 1975 | 1202129 |
| comparative ultrastructural analysis of two tortoise bladders, testudo graeca and geochelone carbonaria. | urinary bladders from the desert tortoises, testudo graeca and geochelone carbonaria were removed at specific times during the year and species in all bladders examined: (1) granular cells, (2) mitochondria-rich cells, and (3) basal cells. cells analogous to these three types have also been observed in amphibian bladders (from toad bufo marinus and bullfrog, rana catesbiana) and reptilian bladders (from pseudemys scripta and clemmys caspica). both tortoises have an incomplete layer of basal cell ... | 1976 | 1252017 |
| descending pathways from the brain stem to the spinal cord in some reptiles. i. origin. | in the present study of the origin of the pathways descending from the brain stem to the spinal cord has been investigated in the reptiles testudo hermanni, pseudemys scripta elegans, tupinambis nigropunctatus and python reticulatus. these reptiles, using highly different types of progression, have been selected, because fundamental variations in the organization of the central motor apparatus are to be expected. the origin of the descending pathways has been demonstrated by recording the occurr ... | 1976 | 1270628 |
| design and control of the head retractor muscle in a turtle, pseudemys (trachemys) scripta: ii. efferent innervation. | the head retractor muscle (rccq) of pseudemys scripta is a useful model in which to study the mechanisms animals use to vary the force and timing of movement. single fibers in this muscle differ significantly in attachments, length, diameter, taper characteristics, and histochemical properties, suggesting that they may be energetically and architecturally specialized for different roles in head movement. in the present paper, we report the peripheral and central efferent innervation of these div ... | 1992 | 1280283 |
| glutamate antagonists that block hyperpolarizing bipolar cells increase the release of dopamine from turtle retina. | some neurochemical features of the neuronal circuitry regulating dopamine release were examined in the retina of the turtle, pseudemys scripta elegans. glutamate antagonists that block hyperpolarizing bipolar cells, such as 2,3 piperidine dicarboxylic acid (pda), produced dose-dependent dopamine release. in contrast, the glutamate agonist 2-amino-4-phosphonobutyric acid (apb), which blocks depolarizing bipolar cell responses with high specificity, had no effect on the release of dopamine. the ga ... | 2017 | 1327088 |
| choroid plexus, ependyma and arachnoidea express receptors for vitamin d: differences between "seasonal" and "non-seasonal" breeders. | autoradiographic studies with [3h]1,25-dihydroxyvitamin d3 demonstrated nuclear high affinity binding sites (receptors) in epithelial cells of choroid plexus, ependyma and arachnoid in "seasonal" breeders of various vertebrate phyla, namely xiphophorus helleri, hyla crucifer, xenopus laevis, bufo woodhousei, chrysemys scripta, anolis carolinensis, nerodia sipedon and phodopus sungorus, but vitamin d receptors were undetectable in these tissues in non-seasonal breeders, such as zebra finch, labor ... | 1992 | 1329147 |
| barbiturate sensitive components of visual erps in a reptile. | the selective effects of methohexital anesthesia were used to differentiate components of visual event-related brain potentials (erps) in pond turtles (pseudemys scripta). tectal and forebrain omitted stimulus potentials (osps) were found to be particularly sensitive to the barbiturate; they are reversibly abolished while the large early wave of the forebrain flash visual evoked potential (vep; 110-120 ms) is reduced by only 27 +/- 11% and that of the tectal vep (55-65 ms) is increased by 40 +/- ... | 1992 | 1330066 |
| gabaa, gabab, and benzodiazepine binding sites in the cerebellar cortex of the red-eared turtle (pseudemys scripta). | we used receptor autoradiography to ascertain the distribution of gabaa and gabab binding sites in the cerebellar cortex of the red-eared turtle (pseudemys scripta). gabaa binding sites were found in both molecular and granule cell layers with highest levels in the granule cell layer. gabab binding sites were found at highest level in the molecular layer. benzodiazepine binding sites were found in approximately equal abundance in both layers. little binding of any ligand was seen in the purkinje ... | 1992 | 1334769 |
| stimulation of in vitro steroidogenesis by pituitary hormones in a turtle (trachemys scripta) within the temperature-sensitive period for sex determination. | to investigate the possible involvement of pituitary hormones in the regulation of steroidogenesis during reptilian sexual differentiation, we tested the ability of gonadotropin (ovine fsh), adrenocorticotropin (porcine acth), and growth hormone (bovine gh) to stimulate in vitro steroidogenesis in embryonic adrenal-kidney-gonad complexes (akgs) of a turtle, trachemys scripta, during and after the temperature-sensitive period for sex determination (tsp). radioimmunoassays were used to measure pro ... | 1992 | 1337278 |
| binding of the benzodiazepine ligand [3h]-ro 15-1788 to membrane preparations of the rabbit and turtle retina. | 1. we have studied the binding of [3h]-ro 15-1788 to membrane preparations of the retina of rabbit (lepus cunicula) and turtle (pseudemys scripta elegans). 2. in both species, [3h]-ro 15-1788 binding was maximal at 0 degrees c and decreased with increasing temperature. it was saturable, protein concentration-dependent and specific. flunitrazepam, unlabelled ro 15-1788 and ethyl-beta-carboline were the most effective displacers, whereas ro 5,4864 was ineffective. 3. in both turtle and rabbit reti ... | 1992 | 1354109 |
| detection of prodynorphin end products in lizard, turtle, and alligator brain extracts. | heterologous radioimmunoassays (rias) for the mammalian prodynorphin end products, alpha-neo-endorphin, dynorphin a(1-17), dynorphin a(1-8), and dynorphin b(1-13) were used to screen brain extracts obtained from representatives of the major surviving orders of reptiles: chelonia (pseudemys scripta), squamata (anolis carolinensis), and crocodylia (alligator mississippiensis). methanol/acid extracts of whole brains obtained from each species were separately fractionated by gel filtration chromatog ... | 2010 | 1355904 |
| monoaminergic systems in the brainstem and spinal cord of the turtle pseudemys scripta elegans as revealed by antibodies against serotonin and tyrosine hydroxylase. | with the aim of gaining more insight into the monoaminergic regulation of spinal motor systems in the turtle, we have studied the distribution of 5-ht (5-htir) and tyrosine hydroxylase immunoreactivity (thir) in the brainstem and spinal cord of pseudemys scripta elegans. 5-htir cell bodies were located in the midline in nucleus raphe inferior, nucleus raphe superior, and laterally in nuclei reticularis superior and inferior and nucleus reticularis isthmi. thir cell bodies were located in the com ... | 1992 | 1361496 |
| adrenal-kidney and gonadal steroidogenesis during sexual differentiation of a reptile with temperature-dependent sex determination. | adrenal-kidney and gonadal steroidogenesis were studied during early development in the red-eared slider turtle, trachemys scripta, which exhibits temperature-dependent sex determination. in vitro steroid secretion by adrenal-kidney-gonad complexes (akgs) incubated for 6 hr was determined by radioimmunoassay (ria). akgs from presumptive males and females secreted progesterone at developmental stages before (stage 15), during (stages 17 and 19), and after (stage 21) the temperature-sensitive peri ... | 2006 | 1426953 |
| design and control of the head retractor muscle in a turtle, pseudemys (trachemys) scripta: i. architecture and histochemistry of single muscle fibers. | we are using the head retractor muscle (rccq) of a turtle, pseudemys scripta, to analyze the neuromuscular mechanisms by which organisms vary the force and timing of muscle contraction. previously we demonstrated that rccq comprises three histochemically defined fiber types: fast glycolytic (fg), fast oxidative glycolytic (fog), and slow oxidative (so). in the present paper we report the 1) architectural features of single muscle fibers in rccq, including their lengths, diameters, and taper char ... | 2006 | 1447408 |
| the orbital glands of the chelonians pseudemys scripta and testudo graeca: comparative histological, histochemical and ultrastructural investigations. | the orbital glands of the chelonians pseudemys scripta and testudo graeca were investigated at the histological, histochemical and ultrastructural levels. four acinar cell types were seen in the harderian gland of p. scripta on the basis of histochemical reactions and ultrastructure. secretory granules were of 2 types, one showing moderate electron density with an electronlucent core, the other being smaller and more osmiophilic with an electron-dense core. in the harderian gland of t. graeca on ... | 1992 | 1452463 |
| diagnostic exercise: high mortality in red-eared slider turtles (pseudemys scripta elegans). | 1992 | 1479815 | |
| cerebral anoxia tolerance in turtles: regulation of intracellular calcium and ph. | to investigate mechanisms of cerebral anoxia tolerance, cerebrocortical intracellular calcium ([ca2+]i) and ph (phi) regulation were compared in turtles (trachemys scripta) and laboratory rats. [ca2+]i and phi in living 200 to 300-microns-thick cortical brain slices were measured with the fluorescent indicators fura-2/acetoxymethyl ester (am) and 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein during exposure to anoxia. within 5 min, [ca2+]i increased to > 1,000 nm in rat brain slices exposed to ... | 1992 | 1481942 |
| specificity of steroid hormone-induced sex determination in a turtle. | the specificity of steroid hormone-induced sex determination was investigated in the red-eared slider, trachemys scripta, a turtle with temperature-dependent sex determination. all eggs were incubated at either a female-producing temperature (31 degrees c) or a male-producing temperature (26 degrees c) and received control or experimental treatments at stage 17-18 of embryonic development. a variety of treatments induced female sex determination at the male-producing temperature. oestradiol-17 b ... | 1992 | 1517701 |
| subcellular enzyme binding and the regulation of glycolysis in anoxic turtle brain. | the association of glycolytic enzymes with the particulate fraction of the cell was assessed in the brain of the freshwater turtle, pseudemys scripta elegans, using three different methodologies. each method showed that a large percentage of each of eight enzymes was bound in brain. the effect of environmental anoxia (5 or 20 h submergence in n2-bubbled water at 7 degrees c) on the distribution of enzymes between free and bound states was analyzed. all three techniques showed a significant incre ... | 1992 | 1532698 |
| a "beat-to-beat" interval generator for optokinetic nystagmus. | an analysis of optokinetic responses was used to derive an iterative model that reproduces the duration of nystagmus slow phases and eye position control during optokinetic nystagmus. optokinetic nystagmus was recorded with magnetic search coils from red-eared turtles (pseudemys scripta elegans) during monocular, random dot pattern stimulation at constant velocities ranging from 0.25-63 degrees/s. the beat-to-beat behavior of slow phase durations was consistent with the existence of an underlyin ... | 1992 | 1540673 |
| hydroxysteroid dehydrogenase activity associated with sexual differentiation in embryos of the turtle trachemys scripta. | many turtles exhibit temperature-dependent sex determination. we have examined the hypothesis that incubation temperature causes a differential expression of steroidogenic enzymes in embryonic turtles. the activities of three steroidogenic enzymes were studied histochemically in turtle (trachemys scripta) embryos at different developmental stages: sexually undifferentiated (stage 15), differentiating (stage 17), and differentiated (stage 26; i.e., hatchling). steroidogenic enzymes were detected ... | 1992 | 1547311 |
| effects of temperature and anoxia on regional cerebral blood flow in turtles. | regional cerebral blood flow (cbf) was measured in isoflurane-anesthetized turtles (pseudemys scripta) by the hydrogen clearance method. teflon-coated platinum electrodes (25 microns) were implanted in the olfactory bulbs, midcerebral cortex and cerebellum in eight adult turtles. the electrodes were voltage clamped at +0.30 v relative to a ag-agcl electrode implanted in the dorsal neck muscles. washout kinetics of h2 gas administered via controlled ventilation was used to calculate local blood f ... | 1992 | 1558224 |
| measurement of plasma thyroxine binding protein in relation to thyroidal condition in the turtle, trachemys scripta, by radioimmunoassay. | polyclonal (rabbit) antisera were generated against a high-affinity plasma thyroxine (t4) binding protein (tbp) purified from the turtle, trachemys scripta, and used to develop a specific radioimmunoassay (ria). the ria demonstrated the presence of an immunochemically related protein in the plasma of several other species of trachemys and in members of several other genera from the same family, emydidae. plasma from all nonemydids and some emydid genera either showed no competition or nonparalle ... | 1992 | 1563614 |
| immunocytochemical and biochemical studies of histamine in the retina of the turtle pseudemys scripta. | a combination of immunocytochemical and biochemical methods was used to study histamine in the turtle retina. histamine-like immunoreactivity was localized within paraboloids of certain cone photoreceptors by use of two different antisera directed against histamine. preincubation of eyecups in ringer's containing 10 microm histamine selectively increased the immunoreactivity of these photoreceptor paraboloids. the present localization of histamine in paraboloids indicated that, although histamin ... | 2000 | 1571959 |
| vestibular afferents innervating the posterior ampullae in a turtle, pseudemys scripta. | 1992 | 1599219 | |
| identification and purification of a high-affinity thyroxine binding protein that is distinct from albumin and prealbumin in the blood of a turtle, trachemys scripta. | fractionation of plasma proteins in the turtle, trachemys scripta, confirmed the presence of a high-affinity thyroxine (t4) binding protein (tbp) that was distinct from albumin (alb) and prealbumin (pa). the tbp was isolated by adsorption on a t4-affinity column and a high degree of purification was achieved by gel filtration and preparative electrophoresis. analysis by reversed-phase hplc showed a single peak of protein with t4 binding activity. the electrophoretic mobility of the tbp, based on ... | 1992 | 1601251 |
| sites of estrogen uptake in embryonic trachemys scripta, a turtle with temperature-dependent sex determination. | female sex determination can be induced in embryonic red-eared slider turtles (trachemys scripta) by exogenous estrogen, as well as by incubation at warm temperature. in the present study, estrogen target areas were identified in embryos before (stage 15), during (stage 18), and after (stage 22) the critical period for sex determination. both hyperfilm and emulsion autoradiography were used to localize tritium accumulation after the injection of radiolabeled 17 beta-estradiol. site-specific trit ... | 1992 | 1617018 |
| norepinephrine activates potassium conductance in neurons of the turtle cerebral cortex. | whole-cell voltage and current clamp recordings were obtained from cortical neurons of the pond turtle, pseudemys scripta elegans. norepinephrine (ne) induced an outward current in 50% of pyramidal neurons. this current had a reversal potential of -88.3 +/- 3.2 mv, consistent with a k+ conductance increase, and had a mean amplitude of 18.3 +/- 7.2 pa at -40 mv. the ionic dependence and pharmacological analyses are both consistent with alpha 2 adrenergic receptor stimulation. inhibition of na(+)- ... | 1992 | 1617428 |
| mechanism of intracardiac shunting in the turtle pseudemys scripta. | two principal hypotheses account for right-left (r-l) intracardiac shunting in reptiles. the "pressure shunting" hypothesis proposes no functional separation between the ventricular cava during systole. the "washout shunting" hypothesis suggests that during systole, the cavum pulmonale (cp) is functionally separate from the rest of the ventricle. the purpose of this study was to test these hypotheses during control, after acetylcholine (ach) administration, after epinephrine (epi) administration ... | 1992 | 1621878 |
| identification of cholecystokinin/gastrin peptides in frog and turtle. evidence that cholecystokinin is phylogenetically older than gastrin. | peptides homologous to mammalian cholecystokinin (cck) and gastrin in brain, antrum, and small intestine of an amphibian (the bullfrog, rana catesbeiana) and a reptile (the turtle, pseudomys scripta) were characterized. all tissues contained peptides reacting with antisera specific for the carboxyamidated c-terminal tetrapeptide common for cck and gastrin. extracts of all tissues, except the turtle antrum, also reacted with an antiserum specific for mammalian sulfated cck, while no extract conta ... | 1992 | 1633800 |
| responses to freezing exposure of hatchling turtles trachemys scripta elegans: factors influencing the development of freeze tolerance by reptiles. | hatchling red-eared turtles trachemys (= pseudemys) scripta elegans (wied) from a louisiana population display a significant ability to withstand the freezing of extracellular body fluids. all animals survived at least 2 h of freezing at -2.5 or -4 degrees c. at -2.5 degrees c, survival declined to 50% after 6 h of freezing and no animals recovered after 24 h or longer, when mean ice content reached 54.7 +/- 1.4% of total body water. at -4 degrees c, all turtles recovered from 4 h of freezing ex ... | 1992 | 1634864 |
| effects of excitatory amino acids and their antagonists on the light response of luminosity and color-opponent horizontal cells in the turtle (pseudemys scripta elegans) retina. | both kainic acid (ka) and n-methyl-d-aspartatic acid (nmda) depolarize luminosity-type horizontal cells (l-type h cells) in normal turtle retina. the presence of both nmda and non-nmda receptors for excitatory amino acids (eaas) on these cells was highlighted by an unusual effect of the noncompetitive nmda-antagonist, mk-801. in retinas that had been exposed to mk-801, the action of nmda was irreversibly altered to one of hyperpolarization, while the depolarizing effect of ka was unaltered. the ... | 1991 | 1675585 |
| excitatory amino acid receptor-mediated transmission in geniculocortical and intracortical pathways within visual cortex. | 1. a preparation of turtle (chrysemys picta and pseudemys scripta) brain in which the integrity of the intracortical and geniculocortical pathways in visual cortex are maintained in vitro has been used to differentiate the excitatory amino acid (eaa) receptor subtypes involved in geniculocortical and intracortical synapses. 2. stimulation of the geniculocortical fibers at subcortical loci produces monosynaptic excitatory postsynaptic potentials (epsps) in visual cortical neurons. these epsps are ... | 1991 | 1681038 |
| lympho-epithelial interactions in the turtle chrysemys scrypta elegans. | the morphological relationships present in the areas of lymphoid infiltration found in the esophagus in chrysemys scripta elegans were studied by the use of light and transmission electron microscopy. these infiltrations are widespread and can be observed in the lamina propria and the covering epithelium. electron microscopy reveals the presence of epithelial cells with differing characteristics at the apex of the lymphoid infiltrations. the introduction of horseradish peroxidase (hrp) into the ... | 1990 | 1695064 |
| changes in turtle brain neurotransmitters and related substances during anoxia. | freshwater turtles (pseudemys scripta elegans) were exposed to 0.5-13 h of anoxia at 25 degrees c, whereupon the brain concentrations of 14 amino acid and monoamine neurotransmitters and related substances were measured. monoamines are of particular interest, because their synthesis and (in part) degradation require molecular oxygen. during anoxia, the level of the inhibitory transmitter gamma-aminobutyric acid (gaba) increased (2.3-fold after 13 h) and the level of the excitatory transmitter gl ... | 1990 | 1696793 |
| chronology and morphology of temperature-dependent sex determination. | temperature sensitivity and gonadal differentiation were studied in a turtle, trachemys scripta, with temperature-dependent sex determination. sex determination was sensitive to both the duration and magnitude of incubation temperature. temperature exerted an "all or none" effect on the ovarian or testicular nature of most gonads, but affected the length of ovaries in a graded fashion. collectively, the results indicate that sex determination is controlled by the quantitative effect of temperatu ... | 1991 | 1744617 |
| localization of aspartate-like immunoreactivity in the retina of the turtle (pseudemys scripta). | aspartate has been reported to be a putative excitatory neurotransmitter in the retina, but little detailed information is available concerning its anatomical distribution. we used an antiserum directed against an aspartate-albumin conjugate to analyze the anatomy, dendritic stratification, and regional distribution of cell types with aspartate-like immunoreactivity in the turtle retina. the results showed dramatic differences in immunoreactivity in the peripheral versus the central retina. stro ... | 1991 | 1761744 |
| calcitonin-gene related peptide is an evolutionarily conserved marker within the amniote thalamo-telencephalic auditory pathway. | the distribution of neurons and fibers containing calcitonin-gene-related peptide (cgrp) was mapped in the thalamo-telencephalic auditory pathways of four amniote species, rats, pigeons (columba livia), caiman (caiman crocodilus), and turtles (pseudemys scripta). in colchicine-treated turtles and pigeons, numerous cgrp+ perikarya were observed in the auditory relay nucleus of the thalamus (n. reuniens of reptiles, and n. ovoidalis of birds). in pigeons, these neurons were most abundant in the ou ... | 1991 | 1765582 |
| refractive state, contrast sensitivity, and resolution in the freshwater turtle, pseudemys scripta elegans, determined by tectal visual-evoked potentials. | visual-evoked potentials (veps) were recorded from the surface of the optic tectum of the freshwater turtle, pseudemys scripta elegans, in response to phase reversal of square-wave gratings of different spatial frequency and contrast. the refractive state of a group of 12 turtles in air was assessed from veps by placing trial lenses in front of the eye. the group mean refraction did not differ significantly from emmetropia, as compared to 4.8 diopters of hyperopia when refracted retinoscopically ... | 1991 | 1772808 |
| ocular dimensions and schematic eyes of freshwater and sea turtles. | measurements were made of the ocular dimensions from living and frozen eyes of one species of freshwater turtle, pseudemys scripta elegans, and of three species of marine turtles, chelonia mydas, dermochelys cariacea, and eretmochelys imbricata. estimates of refractive error by retinoscopy were also obtained with eyes in air and under water. the results suggest that unaccommodated eyes of all four species are approximately emmetropic in air but strongly hyperopic in water. schematic eyes were ca ... | 1991 | 1772809 |
| novel oxidative pathways of sulphapyridine and sulphadiazine by the turtle pseudemys scripta elegans. | the sulphonamides sulphapyridine and sulphadiazine show novel hydroxy metabolites in the turtle pseudemys scripta elegans. in the excreta of the turtles the monohydroxy metabolites 4-hydroxy- and 5-hydroxysulphapyridine and the dihydroxy metabolite 4,5-dihydroxysulphapyridine were detected. of sulphadiazine only dihydroxy metabolites 4,5- and 4,6-dihydroxysulphadiazine were detected. about 70-90% of the dose of sulphapyridine was recovered, while this figure varied between 48 and 69% for sulphad ... | 1991 | 1776236 |
| [the synaptic ribbons in the retina of the turtle (pseudemys scripta elegans): ultrastructural and chronobiological study]. | the authors investigate the morphology and the behaviour of the synaptic ribbons (ns) in the outer plexiform layer of the retina of the turtle pseudemys scripta elegans during the 24 hrs cycle; the animals were subjected to a light-dark cycle = 12:12 hours. new ultrastructural features are demonstrated in the rod arciform density and in the fibers connecting the central axis of the ribbon with the presynaptic membrane (figs. 1 a-b). as to chronobiological data, the existence of different kinds o ... | 2008 | 1781721 |
| synergism between temperature and estradiol: a common pathway in turtle sex determination? | in many reptiles, the temperature at which the eggs are incubated determines the sex of the hatchlings. administration of estradiol will counteract the masculinizing effects of a male-producing temperature, resulting in female hatchlings. to address whether temperature and estrogen are biologically equivalent, two experiments were conducted with the red-eared slider turtle, trachemys scripta. in the first experiment, varying dosages of estrogen were administered at stage 17 (the middle of the te ... | 1991 | 1791420 |
| isolation, purification and primary structure of insulin from the turtle chrysemys dorbigni. | insulin a and b chains from pancreas of the turtle chrysemys dorbigni have been purified to homogeneity, and their primary structures have been determined. the sequence of the a chain is g-i-v-e-q-c-c-h-n-t-c-s-l-y-q-l-e-n-y-c-n, and that of the b chain is a-a-n-q-h-l-c-g-s-h-l-v-e-a-l-y-l-v-c-g-e-r-g-f-f-y-s-p-k-a. the amino acid sequence of chrysemys insulin is identical to that of another turtle (pseudemys scripta), the chicken, and turkey. when compared with alligator insulin, it has three c ... | 1991 | 1808015 |
| calcitonin gene-related peptide, enkephalin and serotonin coexist in neuroepithelial bodies of the respiratory tract of the red-eared turtle, pseudemys scripta elegans. an immunocytochemical study. | the lungs of the red-eared turtle, pseudemys scripta elegans, have been investigated by light-microscopical immunocytochemistry for serotonin (5-ht) and the neuropeptides calcitonin gene-related peptide (cgrp), enkephalin (enk), bombesin, somatostatin, calcitonin and cholecystokinin. cgrp- or 5-ht-like immunoreactivity (li) was demonstrated in neuroepithelial bodies (nebs) and solitary neuroepithelial endocrine cells lying between the ciliated epithelial cells of the intrapulmonary bronchi, and ... | 1991 | 1856111 |
| measuring the lipid content of live animals using cyclopropane gas. | the cyclopropane technique was validated, and it accurately estimated the lipid mass of six pond turtles (trachemys scripta). this technique provided more accurate estimates of lipid mass and lipid-free mass (by difference) than other nonfatal techniques. this technique was accurate despite the turtles' low lipid contents (0.71-3.5% of body mass), variable water contents (65-74% of body mass), and variable body temperatures (approximately 23-31 degrees c). a computer model of the cyclopropane te ... | 1991 | 1887962 |
| chemical regulation of cerebral blood flow in turtles. | this study was performed to test the effect of the chemical composition of the blood on cerebral blood flow (cbf) regulation in turtles. the cbf response to increases in arterial pco2 (paco2) (hypercapnia) was measured during normoxia and anoxia in anesthetized freshwater turtles pseudemys scripta. the radioactive-microsphere technique was used to measure cbf. cbf increased with increases in paco2. the sensitivity of the cbf response to hypercapnia (delta cbf/delta paco2) was 0.68 ml.min-1.100 g ... | 1991 | 1899982 |
| ionic influences on the prolonged depolarization of turtle cones in situ. | 1. the effects of ion channel blockers and ion substitutions on the prolonged depolarization of cones in the retina of the turtle (pseudemys scripta elegans) were studied by intracellular recording. 2. the results of current injection experiments indicate that the prolonged depolarization is regenerative and accompanied by a reduction in the cone's input resistance. 3. the addition of cobalt (5-10 mm) or the removal of extracellular calcium suppressed the prolonged depolarization. raising extrac ... | 1991 | 1900325 |
| progesterone downregulates progesterone receptor, but not estrogen receptor, in the estrogen-primed oviduct of a turtle (trachemys scripta). | progesterone downregulates nuclear progesterone receptor (rp) and estrogen receptor (re) in the estrogen-primed mammalian uterus and chick oviduct. we sought to determine if this downregulation mechanism is operative in the turtle oviduct. female turtles were primed for 4 days with 17-beta-estradiol, after which progesterone (5 mg) was administered by injection every 24 h. re and rp levels in progesterone-treated and control turtle oviducts were measured by [3h]steroid-binding assays (pyridoxal ... | 1991 | 1916218 |
| o-dealkylation and n4-acetylation of sulpha-2-monomethoxine by the turtle pseudemys scripta elegans. | sulpha-2-monomethoxine is n4-acetylated to an extent of 12% of the dose by pseudemys scripta elegans; 48% is excreted unchanged. no o-dealkylation of the 2-methoxy group takes place. | 1991 | 1949545 |
| modulation of neuropeptide-stimulated pituitary hormone secretion in hatchling turtles. | neuropeptides that have relatively narrow actions on mammalian pituitary secretion may have divergent effects on pituitary hormone secretion in ectothermal vertebrates. in turtles, secretion of both thyrotropin (tsh) and growth hormone (gh) can be stimulated in vitro by thyrotropin-releasing hormone (trh) and by members of corticotropin-releasing hormone (crh) and growth hormone-releasing hormone (ghrh) peptide families. to determine if these neuropeptides share common modes of action, and to st ... | 1990 | 1967241 |
| new insights into the reptilian catecholaminergic systems as revealed by antibodies against the neurotransmitters and their synthetic enzymes. | the catecholaminergic systems in the lizard gekko gecko and the turtle pseudemys scripta elegans have been studied with specific and sensitive antibodies against the neurotransmitters dopamine (da) and noradrenaline (na) and the biosynthetic enzymes tyrosine hydroxylase (th), dopamine-beta-hydroxylase (dbh) and phenylethanolamine-n-methyltransferase. our results demonstrate that: (1) the hypothalamic periventricular organ contains both da and na cerebrospinal fluid-contacting cells. these cells ... | 2013 | 1969276 |
| synaptic analysis of amacrine cells in the turtle retina which contain tyrosine hydroxylase-like immunoreactivity. | this study examined amacrine cells in the retina of the turtle pseudemys scripta elegans, which were labelled using an antiserum directed against tyrosine hydroxylase (an enzyme participating in catecholamine synthesis). these cells were investigated using both light and electron microscopy. labelled somata were located in the inner nuclear layer near the border of the inner plexiform layer. the dendritic arborizations of these neurons were tristratified and arborized in strata 1 and 3 and near ... | 1990 | 1972186 |
| isolation and structural characterization of insulin, glucagon and somatostatin from the turtle, pseudemys scripta. | the chelonians occupy an important position in phylogeny representing a very early branching from the ancestral reptile stock. hormonal polypeptides in an extract of the pancreas of the red-eared turtle were purified to homogeneity by reversed phase hplc and their primary structures were determined. turtle insulin is identical to chicken insulin. turtle glucagon differs from chicken glucagon by the substitution of a serine by a threonine residue at position 16 and from mammalian glucagon by an a ... | 1990 | 1974347 |
| genetic damage in a population of slider turtles (trachemys scripta) inhabiting a radioactive reservoir. | turtles inhabiting a radioactive reservoir appear to experience genetic damage due to environmental exposure to low concentrations of long-lived radionuclides. total body burdens for the 50 reservoir turtles examined in the survey ranged from 164.7-4679.3 bq for cesium-137 and from 462.6-5098.3 bq for strontium-90. flow cytometric (fcm) assays of red blood cell nuclei demonstrated significantly greater variation in dna content for the reservoir turtles than for turtles from a nearby, non-radioac ... | 1991 | 1996906 |
| n2-glucuronidation and n4-acetylation of sulphaphenazole by the turtle pseudemys scripta elegans. | after an oral dose of 100 mg of sulphaphenazole, the turtle pseudemys scripta elegans excretes 27% of the compound unchanged and 3.8% as n4-acetylsulphaphenazole. the expected glucuronide conjugate, sulphaphenazole-n2-glucuronide, is not formed and excreted. | 1991 | 2021055 |
| the innervation of the gastrointestinal tract of a chelonian reptile, pseudemys scripta elegans. i. structure and topography of the enteric nerve plexuses using neuron-specific enolase immunohistochemistry. | the general morphological features of the intramural enteric nervous system of a chelonian species, i.e. the red-eared turtle, pseudemys scripta elegans, has been studied in whole-mounts and cryosections by means of neuron-specific enolase immunohistochemistry. a clear visualization of both neuronal cell bodies and nerve fibres allows the recognition of a myenteric plexus as well as a submucous plexus in several gut regions, namely the stomach, midgut and hindgut. the highest innervation density ... | 1991 | 2022490 |
| the innervation of the gastrointestinal tract of a chelonian reptile, pseudemys scripta elegans. ii. distribution of neuropeptides in the myenteric plexus. | the myenteric plexus of the stomach, midgut and hindgut of the red-eared turtle, pseudemys scripta elegans, has been investigated for the occurrence of immunoreactivity to nine neuropeptides. neuropeptide y (npy)-, calcitonin gene-related peptide (cgrp)-, bombesin (bom)- as well as substance p (sp)-like immunoreactivity (li) were found in nerve fibres of all investigated gut regions. from all peptides investigated immunoreactivity for npy was more pronounced. in the stomach npy-li was mainly fou ... | 1991 | 2022491 |