Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| functional venous admixture in the lungs of the turtle, chrysemys scripta. | pulmonary functional venous admixture was determined during forced, unidirectional ventilation with pure o2 and air. at a normal lung volume of 140 ml x kg-1, anatomical shunts (physical bypass of gas exchange surface by the blood) averaged 10% of pulmonary blood flow but it increased to 28% as lung volume declined to 30 ml x kg-1. diffusion limitation and possibly inhomogeneity in ventilation: perfusion ratio also contributed to a total functional venous admixture of about 25% at normal lung vo ... | 1983 | 6622867 |
| acetylation of sulphamethoxazole by fresh water turtles pseudemys scripta elegans. | 1983 | 6632082 | |
| the retinopetal system in the turtle pseudemys scripta elegans. | injections of 125i wheat-germ agglutinin or horseradish peroxidase into the eyes of turtles labeled retrogradely cells in a mesencephalic reticular area lying between the trochlear and the isthmic nuclei. their number was small and they were found predominantly contralateral to the injected eye. these reticular neurons were not labeled following control injections into the orbital cavity and therefore are considered to project to the retina similar to correspondingly located neurons in some othe ... | 1983 | 6640619 |
| some afferent and efferent connections of the vestibular nuclear complex in the red-eared turtle pseudemys scripta elegans. | in the present study some afferent, commissural, and efferent connections of the vestibular nuclear complex in the turtle pseudemys scripta elegans were demonstrated with the hrp tracing technique. afferent projections to the vestibular nuclei were found to arise in the nucleus of the basal optic root, the interstitial nucleus of the fasciculus longitudinalis medialis, the medial and lateral cerebellar nuclei, the perihypoglossal nuclear complex, and the reticular formation. distinct commissural ... | 1983 | 6643738 |
| systemic and renal effects of angiotensin ii in the freshwater turtle pseudemys scripta elegans. | this study examined the renal and systemic effects of angiotensin ii (ang ii) in the freshwater turtle, pseudemys scripta elegans. we infused [asn1, val5]ang ii at doses of 1, 10, 100, and 500 ng x kg-1 x min-1 in conscious turtles while monitoring blood pressure, glomerular filtration rate (gfr), urine volume, and plasma and urine electrolytes. saline (0.6%) was infused for two 1-h control periods at 1 ml x kg-1 x h-1 followed by a 1-h infusion of saline with ang ii added. saline alone was then ... | 1983 | 6660329 |
| the ascending connections of the torus semicircularis central nucleus in chrysemys scripta elegans. | horseradish peroxidase was injected into the torus semicircularis central nucleus of the red-eared turtle chrysemys scripta elegans. the following observations were made. axons originating in the central nucleus project ipsilaterally through the tectoreuniens tract to the ipsilateral nucleus reunions. a second tract leaves the central nucleus medioventrally, courses under the floor of the cerebral aqueduct and terminates as an axonal field in the contralateral central nucleus. finally, there was ... | 1983 | 6662825 |
| chemical structure of angiotensin in the turtle, pseudemys scripta. | the chemical structure of angiotensin generated by incubating kidney extract with homologous plasma from the turtle, pseudemys scripta, has been analyzed. the turtle angiotensin was proposed to be [asp1, val5, his9] ang i by its amino acid composition and by its fluorescent peptide mapping. it was the same structure as angiotensin i in the ox and the sheep. the n-terminal amino acid of the turtle angiotensin was not blocked, unlike that of another reptilian angiotensin found in the snake, elaphe ... | 1984 | 6714649 |
| freeze-fracture study of the turtle lung. 2. rod-shaped particles in the plasma membrane of a mitochondria-rich pneumocyte in pseudemys (chrysemys) scripta. | in thin sections of the lung of the fresh-water turtle pseudemys (chrysemys) scripta some pneumocytes can be distinguished from the remaining pulmonary epithelial cells by a larger amount of mitochondria. in these cells the typical features of type-i and type-ii cells are absent. freeze-fracture replicas reveal rod-shaped particles in the apical plasma membrane of a small population of pneumocytes, which by cytological criteria seem to be identical with the mitochondria-rich cells observed in th ... | 1984 | 6733771 |
| angiotensin and norepinephrine effects on isolated vascular strips from a reptile. | in order to better understand the vascular effects of angiotensin ii (aii) in lower vertebrates, the contractile responses of aortic strips from the freshwater turtle pseudemys scripta elegans were studied. circumferential strips from the left aortic arch were suspended in a tissue bath in 25 degrees c reptilian ringer's solution at ph 7.5. both [asn1,val5] aii (10(-9)-10(-5) m) and norepinephrine (ne) (10(-8)-10(-4) m) produced dose-dependent contractions. the threshold dosage for aii was betwe ... | 1984 | 6735143 |
| phi, contractility and ca-balance under hypercapnic acidosis in the myocardium of different vertebrate species. | the influence of hypercapnic acidosis upon the heart was examined in four vertebrate species. the co2 in the tissue bath was increased from 2.7 to 15% at 12 degrees c for flounder (platichthys flesus) and cod (gadus morhua) and from 3 to 13% at 22 degrees c for turtle (pseudemys scripta) and rainbow trout (salmo gairdneri). during hypercapnia, as previously described, there was a decline and recovery of contractility in heart strips of flounder and turtle, and a sustained decrease in cod and rai ... | 1982 | 6804589 |
| acid-base stress and central chemical control of ventilation in turtles. | central chemical control of ventilation in turtles, chrysemys (pseudemys) scripta, has been characterized by alterations in breathing frequency (f). to assess the effects of acid-base stress on the central ventilatory response, three groups of animals were subjected to 2 h of anoxia (98% n2-2% co2), 2 h of hypercapnia (8% co2 in air), or 2 h of anoxia plus hypercapnia (92% n2-8% co2). ventilatory responses were measured continuously, and arterial blood and cerebrospinal fluid (csf) acid-base var ... | 1982 | 6818207 |
| antigen trapping in the spleen of the turtle, chrysemys scripta elegans. | using horse-radish peroxidase (hrp)-anti-hrp immune complexes, 'antigen trapping' was studied in the spleen of the turtle, chrysemys scripta elegans. it was found that antigen-trapping cells were situated in the periellipsoidal lymphocyte sheath of the white pulp only. the antigen-trapping cells have a dendritic character and a large lobulated nucleus. carbon injections revealed that these cells do not phagocytose. the results are discussed with respect to the phylogeny of antigen-trapping cells ... | 1983 | 6840808 |
| primary afferent projections to the spinal cord and the dorsal column nuclear complex in the turtle pseudemys. | primary afferent projections from cervical and lumbar levels were studied in the turtle pseudemys scripta elegans. injections of radioactive amino acids, wheat germ agglutinin and horseradish peroxidase were made into the dorsal root ganglia or the spinal cord. previous reports on the terminal distribution of primary afferents within the ipsilateral segment of entry were confirmed (kusuma and ten donkelaar 1979, 1980) and additional dorsal root projections were demonstrated to the contralateral ... | 1983 | 6846858 |
| freeze-fracture study of the turtle lung. 1. intercellular junctions in the air-blood barrier of pseudemys scripta. | the air-blood barrier in the lung of the turtle pseudemys scripta was studied by means of freeze-fracture replicas in an attempt to give a detailed account on the structural organization of the intercellular junctions. between the pneumocytes, zonulae occludentes containing 4-19 strands in the apico-basal direction are present; they are considered to be physiologically very tight. in the endothelium, fasciae occludentes, i.e., discontinuous occluding junctions can be found, composed of up to 4 s ... | 1983 | 6850793 |
| supraspinal cell populations projecting to the cerebellar cortex in the turtle (pseudemys scripta elegans). | neuronal cell populations giving rise to cerebellar projections in the turtle, pseudemys scripta elegans, were analysed following injections of horseradish peroxidase into the cerebellar cortex. the most prominent retrograde cell labeling occurred bilaterally within the caudal rhombencephalon and especially in the ventral portion of the inferior reticular field. based on the structural parameters of the labeled cells (size, dendritic tree), their location and laterality of projection, attempts w ... | 1983 | 6861928 |
| ultrastructure of the corpuscular nerve ending in the lymph heart of the turtle (pseudemys scripta elegans). | corpuscular nerve endings were found in the tunica externa of the lymph heart of a turtle (pseudemys scripta elegans). they consisted of axon terminals and surrounding cellular lamellae. serial thin sections of one such presumable sensory corpuscle were made and reconstructed for the three-dimensional analysis of the corpuscle, with special reference to the axon terminals. it was revealed that axon terminals ramified at several points within the corpuscle and formed varicosities of various sizes ... | 1983 | 6870488 |
| the dark brown integumentary pigment of a barnacle (balanus eburneus). a comparative study. | a histochemical analysis involving tinctorial and solubility tests was pursued in conjunction with electron microscopy for the purpose of identifying the dark brown epidermal pigment of a barnacle (balanus eburneus) as melanin and/or ommochrome. histochemically, comparisons were made with other brown pigments located in the subcarapal epidermis of another crustacean, the fiddler crab (uca pugilator), the dorsal skin of the red-backed salamander (plethodon cinereus), the liver and testis of a sli ... | 1983 | 6874419 |
| propriospinal fibers interconnecting the spinal enlargements in some quadrupedal reptiles. | the cells of origin, course and site of termination of long propriospinal fibers interconnecting the intumescences have been studied with the aid of the horseradish peroxidase technique, as well as with anterograde degeneration techniques, in some quadrupedal reptiles (the lizards tupinambis nigropunctatus and varanus exanthematicus, and the turtles testudo hermanni and pseudemys scripta elegans). the anterograde degeneration findings suggest that long descending propriospinal fibers from the ce ... | 1980 | 6933169 |
| baroreflex sensitivity in an amphibian, rana catesbeiana, and a reptilian, pseudemys scripta elegans. | an inverse relationship between heart rate and systematic arterial pressure is demonstrated in unanesthetized bullfrogs (rana catesbeiana) and red-eared turtles (pseudemys scripta elegans). drug-induced elevation of systemic blood pressure resulted in proportional decreases in heart rate and lengthening of the pulse interval. conversely, nitroglycerin-induced decreases in blood pressure produced compensatory increases in heart rate. this relationship in frogs is defined by y = 25.4x + 1684, and ... | 1980 | 6970247 |
| oxygen equilibria of ectotherm blood containing multiple hemoglobins. | complete isocapnic o2 equilibrium curves (o2ec's) and related blood-gas properties are reported for whole blood of the bullfrog (rana catesbeiana) and the aquatic turtle (pseudemys scripta) at temperatures ranging from 5 to 35 degrees c. p50's for bullfrog and turtle blood at physiological ph and 25 degrees c were 36.6 torr (ph 7.83) and 19.3 torr (ph 7.55), respectively. elevation of blood temperature significantly reduced hemoglobin oxygen affinity in both species (delta h = -8.1 and -7.8 kcal ... | 1980 | 6971463 |
| circulatory mechanoreceptors in the pond turtle pseudemys scripta. | this study was undertaken to characterize cardiovascular receptors in the turtle, pseudemys scripta, with particular attention being given to neural activity changes associated with alterations in blood pressure. vagal afferent nerve traffic, synchronous with heart contractions, was recorded in anesthetized artificially ventilated turtles. action potentials, from receptors that fired regularly during each heart cycle, occurred during ventricular systole. mechanical probing and vascular occlusion ... | 1982 | 7065215 |
| the distribution of motoneurons innervating hindlimb muscles in the terrapin pseudemys scripta elegans. | the distribution of motoneurons innervating a number of hindlimb muscles in the spinal cord of the terrapin pseudemys scripta elegans was studied by means of intramuscularly injected horseradish peroxidase (hrp). it appeared that motoneurons innervating knee extensors were localized more rostrally in the spinal cord than those innervating knee flexors and hip retractors. muscles on the dorsal side of the limb were positioned more ventrally in the ventral horn compared to motoneurons innervating ... | 1982 | 7070704 |
| quantitative electron microscopic analysis of the optic nerve of the turtle, pseudemys. | it is estimated by means of electron microscopy that the optic nerve of the turtle pseudemys scripta elegans contains 394,900 fibers of which approximately 80% are myelinated. the total fiber count agrees well with counts obtained from electron microscopic studies on other turtle species. there are, however, differences among these species in the percentage of myelinated fibers in the optic nerve. the axon diameter distribution of the myelinated fibers (excluding myelin) has a mode at 0.87 micro ... | 1982 | 7096642 |
| afferent connections of the cerebellum in various types of reptiles. | the origin of cerebellar afferents was studied in various types of reptiles, viz., the turtles pseudemys scripta elegans and testudo hermanni, the lizard varanus exanthematicus, and the snake python regius, with retrograde tracers (the enzyme horseradish peroxidase and the fluorescent tracer "fast blue"). projections to the cerebellum were demonstrated from the nucleus of the basal optic root, the interstitial nucleus of the fasciculus longitudinalis medialis, the vestibular ganglion, and the ve ... | 1982 | 7107986 |
| organization of nucleus rotundus, a tectofugal thalamic nucleus in turtles. ii. ultrastructural analyses. | nucleus rotundus in a large, tectorecipient nucleus in the dorsal thalamus of the pond turtles pseudemys scripta and chrysemys picta. rotundal neurons form a single, morphologically homogeneous population (rainey, '79) that projects to the dorsal ventricular ridge in the telencephalon. the present paper examines the morphology of and the distribution of synapses upon rotundal neurons. astrocytes, oligodendrocytes, and neurons can be identified in both 1-micrometer sections stained with toluidine ... | 1982 | 7130452 |
| light and electron microscopy of the photoreceptors in the retina of the red-eared slider, pseudemys scripta elegans. | the six different types of photoreceptor in the retina of the turtle pseudemys scripta elegans have been studied by light and electron microscopy. fresh whole-mount retina, in which the oil droplet colors of the photoreceptors could be seen, was compared with fixed tissue cut in the vertical plane. the red single cone (large red oil droplet) is largest in diameter and, in electron microscopy (em) views, has the least opaque oil droplet. it also has a vacuolated paraboloid and a cone pedicle that ... | 1982 | 7130460 |
| distribution and structural characterization of neurons giving rise to descending spinal projections in the turtle, pseudemys scripta elegans. | descending spinal projections were investigated in the turtle pseudemys scripta elegans following injections of horseradish peroxidase and/or radioactive wheat germ agglutinin into the spinal cord at various levels. using various planes of section the cells of origin in the brainstem, cerebellum, and diencephalon were characterized according to their size, dendritic tree, and precise location. projections to levels as far caudal as the lumbar spinal cord were found to arise from medial and later ... | 1982 | 7161413 |
| mesodiencephalic and other target regions of ascending spinal projections in the turtle, pseudemys scripta elegans. | ascending spinal projections were investigated in turtle pseudemys scripta elegans following injections of radioactive amino acids into the spinal cord at various levels. experiments using s35-methionine were most successful in demonstrating various mesodiencephalic target areas. ascending projections from lumbar and cervical segments terminated predominantly in caudal and lateral reticular fields including the perihypoglossal complex. these spinal regions also projected for a lesser extent to r ... | 1982 | 7161414 |
| identification and distribution of neurons presumed to give rise to cerebellar climbing fibers in turtle. a retrograde axonal flow study using radioactive d-aspartate as a marker. | radioactive d-aspartate and horseradish peroxidase were injected into the cerebellar cortex in turtle, pseudemys scripta elegans. while neurons retrogradely labeled with horseradish peroxidase were found in various regions of the spinal cord and brainstem, labeled cells following aspartate injections were only observed in circumscribed regions of the caudal medulla. in rat it was recently reported that climbing fibers, but no other cerebellar afferents, were retrogradely labeled with d-aspartate ... | 1982 | 7172016 |
| evidence for auditory localization ability in the turtle. | evidence is presented that the semiaquatic turtle chrysemys scripta and the terrestrial turtle terrapene carolina major can detect the direction of a tone within their sensitive area of hearing. it is further suggested that not only can these species respond behaviorally to sound without extensive manipulation but can use limited hearing in a problem-solving situation of maze learning. adult emydid turtles (5 c. scripta, 3 t. carolina) learned a y-maze with a 500-c/s signal to an invisible open ... | 1981 | 7186502 |
| the architecture of the spleen of the red-eared slider, chrysemys scripta elegans (reptilia, testudines). | the morphology of the spleen of the red-eared slider, chrysemys scripta elegans, has been described. the outer surface of the spleen is covered by a thin fibromuscular capsule, from which a number of trabeculae extend into the parenchyma. the parenchyma of the spleen shows a definite demarcation into a red and white pulp. the white pulp is composed of two lymphoid compartments: lymphoid tissue surrounds both central arterioles and ellipsoids, forming the periarteriolar and periellipsoidal lympho ... | 1982 | 7186548 |
| characterization of angiotensin pressor responses in the turtle pseudemys scripta. | studies were conducted in turtles (pseudemys scripta) to characterize vascular responses to administration of exogenous angiotensin [asp1-ile5]angiotensin ii (aii). marked pressor responses were present following aii administration (2 microgram/kg iv). the pressor response was completely blocked by concomitant administration of an analogue of aii, [sar1-ile8]aii. both alpha-receptor blockade with phenoxybenzamine or catecholamine depletion by reserpine administration reduced the pressor response ... | 1981 | 7235045 |
| growth of the turtle chrysemys scripta under constant controlled laboratory conditions. | the purpose of this study was to determine 1) growth of the turtle shell and change in weight under constant controlled laboratory conditions and 2) whether under these constant conditions there were seasonal changes. fifty unfed refrigerated eight-week-old hatchling turtles chrysemys scripta were received in october and maintained in aquaria with 16 hours of artificial light and eight hours of darkness, at 24-27 degrees c and a humidity of 30% and fed twice weekly. gross linear measurements of ... | 1981 | 7258687 |
| electron microscope study of vertebrate liver innervation. | liver fine structure was studied in various groups of vertebrates to reveal intrahepatic nerves. nerve fibers were found in the connective tissue of the liver in all mammals, birds, and reptiles studied (japanese monkey, crab-eating monkey, rabbit, guinea pig, rat, golden hamster, pigeon, japanese quail, and turtle, pseudemys scripta). nerve fibers also made direct contact with hepatocytes in these animals except for the rat and the golden hamster. intrahepatic nerves were rare or absent in amph ... | 1981 | 7316686 |
| anatomical distribution of estrogen target neurons in turtle brain. | autoradiographic studies with [3h]estradiol-17 beta in red-eared turtle (pseudemys scripta elegans) show concentration and retention of radioactivity in nuclei of neurons in certain regions. accumulations of estrogen target neurons exist in the periventricular brain with relationships to ventral extensions of the forebrain ventricles, including parolfactory, amygdaloid, septal, preoptic, hypothalamic and thalamic areas, as well as the dorsal ventricular ridge, the piriform cortex, and midbrain-p ... | 1981 | 7317778 |
| atrophic gastritis in a hermann's tortoise (testudo hermanni) and two red-eared turtles (chrysemys scripta elegans). | atrophic gastritis, with concomitant pseudopyloric metaplasia, occurred in a tortoise and 2 turtles. mild gastritis, with some atrophy of gastric glands and minor loss or oxynticopeptic cells which were replaced by mucous cells, was observed in the hermann 's tortoise (testudo hermanni). chronic atrophic gastritis, characterized by inflammation and atrophy of glandular elements, with changes resembling pseudopyloric metaplasia, was seen in 2 red-eared turtles (chrysemys scripta elegans). the 3 a ... | 1981 | 7340590 |
| photoreceptor signals at visual threshold. | electrical responses of cone photoreceptors in the retina of the freshwater turtle have been characterised for flashes and steps of light in darkness and in the presence of background light. these intracellular measurements have been combined with the behavioural increment threshold curve to yield an estimate of 5-10 muv for the signal developed in a cone when the turtle can just detect an increment flash. the signal developed when the cones under the stimulus image are dark-adapted is of intere ... | 1980 | 7360231 |
| acclimation, temperature selection, and heat exchange in the turtle, chrysemys scripta. | turtles acclimated to temperatures between 3 and 19 degrees c were placed in a thermal gradient. the animals usually selected temperatures above 28 degrees c within 1 h after placement in the gradient, attaining a final thermal preferendum between 31 and 33 degrees c. turtles placed in the gradient for extended periods of time were more active during the day; the temperature selected was not related to activity or time of day. turtles were transferred from a constant temperature bath at 10 or 30 ... | 1980 | 7377383 |
| light responses of ganglion cells in the retina of the turtle. | 1. recordings were made from single axons of 218 ganglion cells in the optic nerve of the turtle, pseudemys scripta elegans. responses to light stimuli were used to classify 182 of the cells into four functional groups.2. movement-sensitive cells (113 units) responded best to moving stimuli independent of the stimulus colour or direction of motion. their receptive fields were organized into antagonistic centres and surrounds with the same spectral sensitivity. based on their patterns of response ... | 1980 | 7381765 |
| cells of origin of pathways descending to the spinal cord in some quadrupedal reptiles. | the cells of origin of pathways descending to the spinal cord have been determined in several quadrupedal reptiles, viz., the turtle pseudemys scripta elegans and testudo hermanni and the lizards tupinambis nigropunctatus and varanus exanthematicus, following a technique introduced by kuypers and maisky ('75). this technique was very effective in producing retrograde transport of hrp to a great many neurons in the hypothalamus and in the brain stem. projections from the hypothalamus (the nucleus ... | 1980 | 7419757 |
| basal ganglionic pathways to the tectum: studies in reptiles. | relations between the basal ganglia and the tectum were investigated in two different orders of reptiles: turtles (chrysemys scripta) and crocodilians (caiman crocodilus). in both species, efferents from the paleostriatal complex, a telencephalic region considered comparable to the mammalian basal ganglia on the basis of topographic, histochemical, and hodological criteria, were found to project to a prominent pretectal cell group called the dorsal nucleus of the posterior commissure (ndcp). cel ... | 1980 | 7440783 |
| distribution of ventilation in the turtle pseudemys scripta. | spontaneously ventilating turtles, pseudemys scripta, were allowed to rebreathe 133xe to equilibrium. frequent gamma camera images were obtained and processed to allow regional evaluation of ventilation. the distribution of ventilation was markedly inhomogeneous, with washin to equilibrium most rapid in anterior lung compartments and slowest in posterior lung compartments. similarly washout from equilibrium was most rapid in anterior compartments and slowest in posterior compartments. during apn ... | 1980 | 7444225 |
| comparison of the pineal complex, retina and cerebrospinal fluid contacting neurons by immunocytochemical antirhodopsin reaction. | the presence of rhodopsin was investigated by an indirect immunocytochemical method in the pineal complex of various vertebrates (carassius auratus, cyprinus carpio, hypophthalamichthys molitrix, lucioperca lucioperca, triturus vulgaris, bombina bombina, rana esculenta, pseudemys scripta elegans, lacerta agilis et viridis, white leghorn chickens, rat), in the retina of lebistes reticulatus, lucioperca lucioperca, rana esculenta, lacerta agilis, pseudemys scripta elegans, the chicken and the rat, ... | 1980 | 7456628 |
| the frequency selectivity of auditory nerve fibres and hair cells in the cochlea of the turtle. | 1. the electrical responses of single auditory nerve fibres or cochlear hair cells were recorded in the isolated half-head of the turtle pseudemys scripta elegans. responses to sound stimuli presented to the tympanum could be recorded for at least 4 hr after isolation.2. impulses were recorded extracellularly from single auditory nerve fibres. for tones of suprathreshold intensity the impulses occurred with a preferred phase relation (i.e. they were phase-locked) to the cycles of the sound stimu ... | 1980 | 7463380 |
| distribution of glial fibrillary acidic protein-immunopositive structures in the brain of the red-eared freshwater turtle (pseudemys scripta elegans). | the distribution of glial fibrillary acidic protein (gfap)-immunoreactivity is described in serial vibratome sections of the turtle brain. the results are discussed in relation to our previous studies of rat and chicken brains. in the turtle brain, the distribution of gfap-positive elements is rather evenly abundant as compared to that observed in the chicken and rat. the gfap-positive structures are fibers of different length and orientation, but the stellate cells are not gfap-positive. the ba ... | 1994 | 7522421 |
| nitric oxide synthase in the brain of the turtle pseudemys scripta elegans. | the distribution pattern of nitric oxide synthase (nos) was investigated in the brain of the turtle by nadph-diaphorase histochemistry. the specificity of the histochemical staining was tested by immunocytochemical colocalization with an antiserum specific for nos. in the forebrain, neurons staining intensely for nitric oxide synthase were localized in the olfactory tubercle, the basal ganglia complex, the basal amygdaloid nucleus, suprapeduncular nucleus, and the posterior hypothalamic area. ma ... | 1994 | 7529267 |
| complexity and scaling properties of amacrine, ganglion, horizontal, and bipolar cells in the turtle retina. | in the present study we have evaluated the complexity and scaling properties of the morphology of retinal neurons using fractal dimension as a quantitative parameter. we examined a large number of cells from pseudemys scripta and mauremys caspica turtles that had been labeled using golgi-impregnation techniques, intracellular injection of lucifer yellow followed by photooxidation, intracellular injection of rhodamine conjugated horseradish peroxidase, or intracellular injection of lucifer yellow ... | 1994 | 7529776 |
| expression of alpha sm actin in terrestrial ectothermic vertebrates. | alpha-smooth muscle (alpha sm) actin of endothermic vertebrates is selectively recognized by the monoclonal antibody anti-alpha sm-1. immunoreactivity to this antibody has been shown to be localized in the nh2-terminal sequence ac-eeed (chaponnier et al. 1994). among terrestrial ectothermic vertebrates, two amphibian (triturus vulgaris, rana esculenta) and three reptilian species (pseudemys scripta elegans, natrix natrix, podarcis sicula) were screened to investigate if their vascular and viscer ... | 1995 | 7553770 |
| vitellogenin induction by xenobiotic estrogens in the red-eared turtle and african clawed frog. | many environmental pollutants have estrogenic activity in animals. xenobiotic estrogens include many pesticides and industrial chemicals that biocumulate. the impact of these common pollutants on the reproductive success of wildlife may be considerable, particularly in threatened or endangered species. this research examined the use of plasma vitellogenin in males as a biomarker for estrogenic xenobiotics in reptiles and amphibians. adult male turtles (trachemys scripta) and frogs (xenopus laevi ... | 1995 | 7556019 |
| enzymatic control of glycogenolysis during anoxic submergence in the freshwater turtle trachemys scripta. | freshwater turtles trachemys scripta elegans endure prolonged severe hypoxia, and even complete anoxia, while diving or hibernating underwater. metabolic adaptations supporting survival include the activation of glycogenolysis and glucose output from liver, as well as strong metabolic rate depression. the present study analyzes the enzymes of both the phosphorolytic (glycogen phosphorylase, phosphorylase b kinase, camp-dependent protein kinase) and glucosidic (alpha-glucosidase) pathways of glyc ... | 1995 | 7584617 |
| short-term effects of dopamine on photoreceptors, luminosity- and chromaticity-horizontal cells in the turtle retina. | the effects of dopamine on luminosity-type horizontal cells have been documented in different vertebrate retinas, both in vivo and in vitro. some of these effects may reflect direct action of dopamine onto these cells, but indirect effects mediated by presynaptic neurons cannot be ruled out. furthermore, direct effects of dopamine on horizontal cells may affect other, postsynaptic neurons in the outer plexiform layer. to test these possibilities, we studied the effects of dopamine on photorecept ... | 2013 | 7654600 |
| camp-dependent protein kinase and anoxia survival in turtles: purification and properties of liver pka. | the catalytic subunit of turtle (trachemys scripta elegans) liver cyclic amp-dependent protein kinase (pkac) was purified to homogeneity with a final specific activity of 65,783 pmol phosphate transferred.min-1.mg protein-1. subunit molecular weight was 42-43 kda as determined by sds-page and sephacryl s-300 chromatography. the isolectric point was ph 6.41 +/- 0.02. turtle liver pkac showed highest activity with kemptide as its substrate; activity with other artificial substrates, histone iia an ... | 1995 | 7659081 |
| fiber-type composition of hindlimb muscles in the turtle, pseudemys (trachemys) scripta elegans. | a description is provided of the fiber-type composition of several hindlimb muscles of the adult turtle, pseudemys (trachemys) scripta elegans. in addition, cross-section areas of each fiber type and an estimation of the relative (weighted) cross-section area (wcsa) occupied by the different fiber types are also provided. seven muscles were selected for study, based on their suitability for future neurophysiological analysis as components of the segmental motor system, and on their homologies wi ... | 1995 | 7666437 |
| a commentary on the segmental motor system of the turtle: implications for the study of its cellular mechanisms and interactions. | a commentary is provided on the segmental motor system of the turtle pseudemys (trachemys) scripta elegans with an emphasis on neuronal, neuromuscular, and muscular mechanisms that control the development of force under normal, fatiguing, and pathophysiological conditions. for the central neuronal component of the segmental motor system, it has recently been shown that intracellular analysis of the firing properties of motoneurons and interneurons can be undertaken for relatively long periods of ... | 1995 | 7666438 |
| effect of anoxia on isolated turtle tissues: is the response to anoxia mediated by protein kinase second messengers? | organ slices from the turtle trachemys scripta elegans were incubated under aerobic and anoxic conditions to examine the effect of protein kinase (prk) second messengers in potentiating the biochemical responses to anoxia exposure. incubating liver slices from aerobic animals under anoxic conditions produced biochemical changes exactly similar to those observed in vivo: phosphofructokinase (pfk) was more sensitive to citrate inhibition and the percentage of glycogen phosphorylase (gp) in the act ... | 1994 | 7696998 |
| electrocardiography in anaesthetised red-eared sliders (trachemys scripta elegans). | electrocardiographic (ecg) values were measured in nine red-eared sliders (trachemys scripta elegans), anaesthetised with either ketamine, ketamine/xylazine or ketamine/midazolam, for the purpose of cardiocentesis. lead ii traces were then recorded through three cutaneous electrodes. the ecg complexes consisted of small upright p waves, larger r waves and no q or s wave deflections, very long qt intervals, small upright t waves, and a short tp interval. no sv waves were recorded. this pattern wa ... | 1995 | 7709064 |
| microvascularization of the cerebellum in the turtle, pseudemys scripta elegans (reptilia). a scanning electron microscope study of microvascular corrosion casts, including stereological measurements. | cerebellar blood supply and microvascular patterns were studied in 12 freshwater turtles pseudemys scripta elegans by scanning electron microscopy (sem) of microvascular corrosion casts and histology. vascular densities were estimated by point counting methods from casts and thin sections (7 microns). short a2-arterioles and recurrent branches from a3-arterioles supply the capillary bed of the molecular layer, while v2 and v3 venules drain it. the purkinje cell layer is supplied by horizontal br ... | 1995 | 7726392 |
| conservation and dynamics of microsatellite loci over 300 million years of marine turtle evolution. | microsatellite loci consisting of (ca)n repetitive arrays were obtained from three species of marine turtle, and primers were designed to test for polymorphism within species and the persistence of microsatellites across species. homologous loci were found in each test of six marine species within two families (cheloniidae and dermochelyidae), as well as in a freshwater species (emydidae, trachemys scripta), which indicates a conservation of flanking sequences spanning approximately 300 million ... | 1995 | 7739385 |
| upregulation of the gabaa/benzodiazepine receptor during anoxia in the freshwater turtle brain. | the freshwater turtle brain survives anoxia by decreasing its energy expenditure. during this anoxic period there is a sustained release of the inhibitory neurotransmitter gamma-aminobutyric acid (gaba). this study investigated whether there was a corresponding change in the binding properties of the gabaa/benzodiazepine (gaba/bdz) receptor. turtles (trachemys scripta) were subjected to a 100% n2 atmosphere for up to 24 h. after exposure, the cerebral cortex was dissected out, and saturation bin ... | 1995 | 7771598 |
| insulin-like growth factor-i in the plasma of two reptiles: assay development and validations. | radioimmunoassays (rias) of insulin-like growth factor-i (igf-i) in nonmammals are complicated by two problems: decreased specificity due to heterologous assays and assay interference from igf binding proteins. we have developed and validated an ria for the detection of igf-i in reptilian plasma that circumvents these problems. biochemical validations show parallelism between standard curves, plasma dilutions, and internal standards. further, biological validations indicate that (1) plasma igf-i ... | 1995 | 7781962 |
| spectral properties of turtle cones. | microelectrodes were used to record from red and green cones of the turtle pseudemys scripta elegans. the purpose of this study was to determine the action spectra of the red and green cone photopigments, and to look closely for direct interactions between the two cone classes. an isolated retina preparation was employed so that cones could be stimulated from the outer segment side, thereby avoiding the oil droplets that reside in the inner segments of many cones and normally filter incident lig ... | 2008 | 7786854 |
| estrogen downregulation of albumin and a 170-kda serum protein in the turtle, trachemys scripta. | we examined changes in serum protein composition after estradiol-17 beta treatment of ovariectomized female trachemys scripta, with the objective of identifying proteins that are repressed by estrogen. the experimental protocol was validated by measuring serum estradiol-17 beta levels with a specific radioimmunoassay. control turtle sera contained little or no estradiol-17 beta (mean = 25.8 pg/ml) while estrogen-treated turtle sera had elevated estradiol-17 beta levels (mean = 333.3 pg/ml). estr ... | 1995 | 7789749 |
| a tetraethylammonium-insensitive inward rectifier k+ channel in müller cells of the turtle (pseudemys scripta elegans) retina. | ion channels present in isolated glial (müller) cells from the retina of the turtle (pseudemys scripta elegans) were studied with the patch clamp technique. the predominant conductance in these cells was due to an inward rectifying potassium current. the whole-cell conductance of the inward rectifier was 20.2 +/- 1.9 ns (n = 7 cells) in a standard extracellular saline solution (3 mm extracellular potassium). this conductance was dependent on the extracellular potassium concentration, with a 2.88 ... | 1994 | 7807523 |
| role of reductase and aromatase in sex determination in the red-eared slider (trachemys scripta), a turtle with temperature-dependent sex determination. | in many turtles the temperature during the middle of incubation determines the gonadal sex of the hatchling. in the red-eared slider turtle (trachemys scripta), an incubation temperature of 26 degrees c results in all male offspring, whereas an incubation temperature of 31 degrees c results in all female offspring; at temperatures intermediate to these (e.g. 29, 29.2, 29.4 degrees c) a mixed sex ratio is obtained. administration of exogenous oestrogens will overcome the effects of an all-male pr ... | 1994 | 7829992 |
| atrial natriuretic factor in the freshwater turtle pseudemys scripta: a partial characterization. | the presence of natriuretic and vasorelaxant materials in the atria and ventricles of a chelonian reptile, the freshwater turtle pseudemys scripta, was verified and the active substance partially characterized. crude atrial and ventricular extracts were acutely natriuretic and diuretic when administered to anesthetized rats increasing sodium excretion 23.5 +/- 7.9 and 5.11 +/- 18 microm na/10 min/mg extract, respectively. although atrial extracts were relatively more natriuretic than ventricular ... | 1994 | 7851726 |
| effects of anoxia on protein phosphatase in turtle organs: purification and properties of protein phosphatase type-1 from turtle liver. | protein phosphatase type 1 (pp-1) was analyzed in organs of the red-eared slider turtle, trachemys scripta elegans, a species capable of long-term anoxia survival. during anoxic submergence at 7 degrees c, pp-1 activity in liver rapidly decreased to 63% of the control value within the first hour and remained suppressed over the subsequent 20 h of anoxia. pp-1 activity was also suppressed in red skeletal muscle during anoxia and dropped transiently (after 1 h) in brain but did not change in heart ... | 1995 | 7864641 |
| functional morphologies of retinal ganglion cells in the turtle. | retinal ganglion cells in the turtle, pseudemys scripta elegans, were examined by intracellular recording with a protocol of stationary and moving lights. responses were apportioned among off, on, and on-off categories, and directional selectivity. cells were injected with neurobiotin, then later conjugated with avidin-horseradish peroxidase in standard procedure. morphological analysis of the stained cells included measurements of soma and dendritic field sizes, dendritic stratification, number ... | 1994 | 7890834 |
| juvenile turtles for mosquito control in water storage tanks. | juvenile turtles, trachemys scripta, provided highly effective control of mosquito larvae in cement tanks (pilas) where water was stored for household cleaning. when single turtles were introduced to tanks with histories of high mosquito production, nearly all turtles remained in good health and no mosquito larvae survived to the pupal stage. families welcome turtles in their water storage containers in honduras. humane conditions for turtles can be assured by providing small quantities of table ... | 1993 | 7902872 |
| identification of cholecystokinin from frog and turtle. divergence of cholecystokinin and gastrin occurred before the evolution of amphibia. | cholecystokinins from brain and small intestine of the bullfrog (rana catesbeiana) and red-eared slider turtle (pseudomys scripta) were isolated. the purifications were monitored by an antiserum specific for the common c-terminus of mammalian cholecystokinin and gastrin. the peptide structures were identified by sequence analysis of the intact peptides and proteolytic fragments, mass spectrometry, and amino acid analysis. brain and small intestine of both species contained cholecystokinin-8 and ... | 1994 | 7925386 |
| the relation of the dual thyroxine/vitamin d-binding protein (tbp/dbp) of emydid turtles to vitamin d-binding proteins of other vertebrates. | the relation of a dual binding protein, involved in the transport of both thyroxine (t4) and vitamin d3, in the blood of emydid turtles to blood proteins in other vertebrates was examined immunologically. binding studies with 25-oh-[3h]cholecalciferol (d3) confirmed the presence of a d3-binding protein (dbp) in the plasma of a wide variety of chelonian species representing both major suborders, as well as other species of reptiles, amphibians, birds, and mammals. analysis by polyacrylamide gel e ... | 1994 | 7926631 |
| functional architecture of vestibular primary afferents from the posterior semicircular canal of a turtle, pseudemys (trachemys) scripta elegans. | physiological studies in many vertebrates indicate that vestibular primary afferents are not a homogeneous population. such data raise the question of what structural mechanisms underlie these physiological differences and what functional role is played by afferents of each type. we have begun to answer these questions by characterizing the architecture of 110 afferents innervating the posterior canal of pseudemys scripta. we emphasize their spatial organization because experimental evidence sug ... | 1994 | 7929889 |
| anatomical characterization of retinal ganglion cells that project to the nucleus of the basal optic root in the turtle (pseudemys scripta elegans). | there is little detailed information about retinal ganglion cells which project to specific central targets in the brain. the present study examined retinal ganglion cells projecting to the nucleus of the basal optic root, a major accessory retinal target in the turtle. these ganglion cells were first selectively labeled using retrograde transport of rhodamine injected stereotaxically into the nucleus of the basal optic root. the number and distribution of the retrogradely labeled cells in the r ... | 1994 | 7969940 |
| anoxia induces changes in translatable mrna populations in turtle organs: a possible adaptive strategy for anaerobiosis. | the effects of anoxic submergence (16 h at 15 degrees c) on cellular mrna contents were assessed in five organs of anoxia tolerant turtles trachemys scripta elegans. poly(a)+ rna was extracted from liver, red and white skeletal muscle, kidney and heart of control and anoxic turtles, as well as from heart and kidney of turtles allowed 24 h aerobic recovery (at 15 degrees c) after anoxia exposure. poly(a)+ rna content increased by 30% in white muscle from anoxic turtles relative to control animals ... | 1994 | 7983251 |
| distribution of target cells for 1,25-dihydroxyvitamin d3 in the brain of the yellow bellied turtle trachemys scripta. | five h after injection of tritiated 1,25-dihydroxyvitamin d3 into trachemys scripta, neurons with nuclear concentrations of radioactivity were identified in distinct regions within the central nervous system. coinjection of a 100-fold excess of non-labeled 1,25-dihydroxyvitamin d3 abolished or reduced the specific nuclear binding of tracer. target neurons were present in ventral periventricular brain regions including tuberculum olfactorium, nucleus accumbens, cortex piriformis, primordium hippo ... | 1994 | 8004456 |
| putative aromatase inhibitor induces male sex determination in a female unisexual lizard and in a turtle with temperature-dependent sex determination. | treatment of developing embryos of two diverse species of reptiles with fadrozole (a potent and specific nonsteroidal inhibitor of aromatase activity in mammals) resulted in the induction of male sex determination. in the first experiment, males were produced in an all-female parthenogenic species of lizard (cnemidophorus uniparens). in the second experiment, male sex determination was induced in a turtle (trachemys scripta) with temperature-dependent sex determination. the results support the h ... | 1994 | 8046299 |
| temperature and cerebral blood flow regulation in the freshwater turtle, pseudemys scripta. | chemical regulation of cerebral blood flow (cbf) by co2 has been demonstrated in an ectohermic vertebrate (davies, am. j. physiol. 260: r382, 1991). cerebrovascular sensitivity to co2 (delta cbf/delta paco2), a measure of the vascular reactivity of the cerebral blood vessels to co2, was found to be 0.7 ml.min-1.100 g-1.torr-1 during normoxia and 3.4 during anoxia in the freshwater turtle, pseudemys scripta. in the present study, the effect of body temperature on delta cbf/delta paco2 was studied ... | 1994 | 8059076 |
| occurrence and localization of calbindin-d28k in kidney and cerebellum of the slider turtle, trachemys scripta. | since its initial discovery in the avian intestine, calbindin-d28k has been reported to occur in various species and tissues. although calbindin-d28k binds calcium ions in the physiologically relevant range of intracellular calcium, its functional role in the various cell types where it has been localized remains unknown. | 1994 | 8059980 |
| temperature-dependent sex determination in reptiles: proximate mechanisms, ultimate outcomes, and practical applications. | in many egg-laying reptiles, the incubation temperature of the egg determines the sex of the offspring, a process known as temperature-dependent sex determination (tsd). in tsd sex determination is an "all or none" process and intersexes are rarely formed. how is the external signal of temperature transduced into a genetic signal that determines gonadal sex and channels sexual development? studies with the red-eared slider turtle have focused on the physiological, biochemical, and molecular casc ... | 1994 | 8062460 |
| time course of anoxia-induced increase in cerebral blood flow rate in turtles: evidence for a role of adenosine. | the exceptional ability of the turtle brain to survive prolonged anoxia makes it a unique model for studying anoxic survival mechanisms. we have used epi-illumination microscopy to record blood flow rate in venules on the cortical surface of turtles (trachemys scripta). during anoxia, blood flow rate increased 1.7 times after 45-75 min, whereupon it fell back, reaching preanoxic values after 115 min of anoxia. topical superfusion with adenosine (50 microm) during normoxia caused a 3.8-fold incre ... | 1994 | 8063883 |
| regulation of central vascular blood flow in the turtle. | the purpose of this study was to determine the effects of vagal nerve stimulation on the pulmonary and systemic circulations in the turtle pseudemys scripta. the heart rate (hr), systemic vascular resistance (rsys), pulmonary vascular resistance (rpul), total pulmonary blood flow (qpul), and total systemic blood flow (qsys) were measured during electrical stimulation of the vagal efferent and the vagal afferent nerves. vagal efferent nerve stimulation resulted in a bradycardia, increased rsys an ... | 1994 | 8067470 |
| light adaptation and photopigment bleaching in cone photoreceptors in situ in the retina of the turtle. | light adaptation and photopigment bleaching in cone photoreceptors were studied in the intact, superfused retina of the turtle (pseudemys scripta elegans). a new method for measuring changes in the photopigment of cones is described. action spectrum measurements indicate that the signals arise from the red-sensitive cones. measurements of steady-state bleaching are well described by the monomolecular bleaching equation with a half-bleaching constant of about 5.5 log photons sec-1 microns-2. quan ... | 1994 | 8120614 |
| thyroxine-binding protein represents the major vitamin d-binding protein in the plasma of the turtle, trachemys scripta. | structural homology between the high-affinity thyroxine (t4)-binding protein (tbp) in the plasma of the turtle, trachemys scripta, and vitamin d-binding proteins (dbp) of mammals prompted an investigation of plasma vitamin d binding in the turtle. several lines of evidence indicate that the tbp represents the primary binding protein for 25-oh-cholecalciferol (d3) in the turtle plasma. d3-binding protein in whole plasma migrates in the same position as tbp by size-exclusion chromatography and pol ... | 1994 | 8138122 |
| an analysis of the proopiomelanocortin systems in the pituitary of the squamate reptile lacerta galloti. | acid extracts of the pars intermedia of the squamate reptile lacerta galloti were screened for immunoreactive forms of proopiomelanocortin (pomc)-related end products following sephadex g-50 column chromatography. alpha-msh-sized end products were detected with a val-nh2, c-terminal-specific ria, and beta-endorphin-sized end products were detected with a separate c-terminal-directed ria. five peaks of alpha-msh-related immunoreactivity were isolated following fractionation by reversed-phase hplc ... | 1994 | 8194743 |
| glucuronidation of naproxen by the turtle pseudemys scripta elegans. | 1994 | 8196098 | |
| glucuronidation of flumequine by the turtle pseudemys scripta elegans. | 1994 | 8196100 | |
| in vivo gnrh responsiveness of lh secretion in the female turtle, trachemys scripta, in relation to the reproductive stage. | the effects of several forms of gonadotropin-releasing hormone (gnrh) on the in vivo secretion of luteinizing hormone (lh) were investigated in the female turtle trachemys scripta. serial injections of large vitellogenic turtles with 1-2 micrograms (ca. 0.15 micrograms/100 g turtle) of chicken gnrh-i (cgnrh-i) and multiple blood sampling revealed that mature females were unresponsive to gnrh. in contrast, both forms of avian gnrh, cgnrh-i and cgnrh-ii, and an avian gnrh analogue (gnrha) signific ... | 1993 | 8224759 |
| differential n-acetylation of alpha-msh and beta-endorphin in the intermediate pituitary of the turtle, pseudemys scripta. | steady-state analyses of the intermediate pituitary of the turtle, pseudemys scripta, indicated that alpha-msh-sized immunoreactive forms and beta-endorphin-sized immunoreactive forms are major end products of melanotropic cells. three forms of alpha-msh-related immunoreactivity were detected. the two major forms had the same reversed-phase hplc properties as synthetic n,o-diacetyl-acth(1-13)-nh2 and n-acetyl-acth(1-13)-nh2. these forms accounted for 97% of the total alpha-msh-related immunoreac ... | 2007 | 8234035 |
| sensitive stages for the effects of temperature on gonadal aromatase activity in embryos of the marine turtle dermochelys coriacea. | many data suggest an involvement of estrogens in gonadal differentiation in reptiles with temperature-dependent sex determination (tsd). however, the site of estrogen synthesis in two species of freshwater turtles is unclear. in emys orbicularis, estrogens were shown to be produced by the gonads, whereas in trachemys scripta, gonadal steroids were not detected. the marine turtle dermochelys coriacea exhibits tsd but in gonadal development, ovarian differentiation is delayed. gonadal aromatase ac ... | 1993 | 8262357 |
| the orbital glands of the terrapin pseudemys scripta in response to osmotic stress: a light and electron microscope study. | the histochemical and ultrastructural features of both orbital glands--the anterior lacrimal and harderian glands--were compared in the terrapin pseudemys scripta following adaptation either to distilled water or to seawater. seawater adaptation activated the harderian gland and caused a major structural reorganisation. type i cells increased in number, whereas type ii cells became smaller and less numerous. the most striking change was shown by the type iv cells which display the features of a ... | 1993 | 8270473 |
| de novo protein synthesis and protein phosphorylation during anoxia and recovery in the red-eared turtle. | changes in de novo protein synthesis and protein phosphorylation were monitored during anoxia and recovery in the red-eared slider trachemys (= pseudemys) scripta elegans. time courses of 35s-radiolabeled methionine incorporation into acid-precipitable material showed an increase up to 5 h postinjection and remained constant after this time. comparison of the total and acid-precipitable 35s label incorporation into tissues from 20-h control, anoxic, and recovering animals showed differences betw ... | 1993 | 8285280 |
| role of aromatization in testosterone-induced inhibition of luteinizing hormone secretion in female turtles, trachemys scripta. | both 17 beta-estradiol (e2) and testosterone (t) were shown to inhibit in vitro pituitary lh secretion in the turtle trachemys scripta. since t was approximately 500 times less potent than e2, and 5 alpha-dihydrotestosterone was even less active than t, the inhibitory action of t may result from its aromatization to estrogen. we utilized both in vivo and in vitro approaches to elucidate the roles of t and estrogen in the negative feedback of pituitary lh secretion. gonadectomy of adult (vitellog ... | 1994 | 8312438 |
| species and tissue distribution of the regulatory protein of glucokinase. | rat liver is known to contain a regulatory protein that inhibits glucokinase (hexokinase iv or d) competitively versus glucose. this inhibition is greatly reinforced by the presence of fructose 6-phosphate and antagonized by fructose 1-phosphate and by kcl. this protein was now measured in various rat tissues and in the livers of various species by the inhibition it exerts on rat liver glucokinase. rat, mouse, rabbit, guinea-pig and pig liver, all of which contain glucokinase, also contained bet ... | 1993 | 8373368 |
| estrogen- and temperature-induced medullary cord regression during gonadal differentiation in a turtle. | gonadal differentiation associated with estrogen-induced female sex determination was examined in a turtle with temperature-dependent sex determination, and was compared to ovarian differentiation at a female-producing temperature. freshly ladi eggs of the red-eared slider, trachemys scripta, were incubated at a male-producing temperature (26 degrees c) and were experimentally manipulated at one of three embryonic stages: stage 15, 17, or 20 (i.e. early, midway, or late in the temperature-sensit ... | 1993 | 8405765 |
| ectoplasmic ("junctional") specializations in sertoli cells of the rooster and turtle: evolutionary implications. | ectoplasmic specializations are complex actin-containing structures found at certain sites of intercellular attachment in sertoli cells. current evidence indicates that these structures are a form of actin-associated adhesion junction. in the turtle (pseudemys scripta) and rooster (gallus domesticus) ectoplasmic specializations are known to occur adjacent to sites of attachment to elongate spermatids and are characterized by a layer of "loosely" cross-linked actin filaments that lies next to the ... | 1993 | 8417627 |
| comparative studies of thyroxine binding proteins in turtle plasma using column chromatography. | thyroxine (t4) binding proteins in turtle plasma were compared with those of various mammalian and nonmammalian (fish, birds) species using gel filtration chromatography (bio-gel). high-affinity t4 binding was observed in all mammals studied, in the chicken, and in one species of turtle, trachemys scripta. this high affinity t4 binding protein (tbp) appears to be the major component of t4 transport in the turtle; selective removal of this tbp greatly diminished binding activity in t. scripta pla ... | 1993 | 8428644 |
| gnrh-induced desensitization of in vitro luteinizing hormone secretion in the turtle, trachemys scripta. | gonadotropin-releasing hormone (gnrh)-induced desensitization of pituitary luteinizing hormone (lh) secretion in female turtles (trachemys scripta) was investigated by in vitro superfusion of whole or hemipituitaries with the endogenous forms of the peptide. in sub-adults, lh secretion was rapidly attenuated (desensitized) by both prolonged and pulsatile treatments of chicken ii gnrh (cii-gnrh), but pulsatile gnrh administration was more effective than prolonged administration in stimulating lh ... | 1993 | 8454169 |
| differential distribution of chicken-i and chicken-ii gnrh in the turtle brain. | chicken-i and chicken-ii gonadotropin-releasing hormone (ci-gnrh and cii-gnrh) were shown to be differentially distributed in the brain of a turtle, trachemys scripta, by hplc and specific radioimmunoassays. the ci-gnrh was most concentrated in the median eminence (me), while cii-gnrh was most concentrated in the caudal brain regions, especially medulla and cerebellum. the ratio of ci- to cii-gnrh in the me of adults was 8:1. age- and sex-related differences in gnrh concentrations were observed ... | 1993 | 8483800 |
| synaptic microcircuitry of bipolar and amacrine cells with serotonin-like immunoreactivity in the retina of the turtle, pseudemys scripta elegans. | although serotonin is thought to be a neurotransmitter in a number of retinal systems, much of the precise synaptic connectivity of serotonergic neurons is unknown. to address this issue, we used an antiserum directed against serotonin to label serotonergic bipolar and amacrine cells in the turtle retina. light-microscopic analysis of labeled amacrine and bipolar cells indicated that both had bistratified dendritic arborizations primarily in stratum 1 and in strata 4/5 of the inner plexiform lay ... | 2013 | 8494799 |
| binding affinities of thyroxine-binding proteins in turtle plasma. | binding affinities (ka) for thyroxine (t4) by blood plasma and purified plasma proteins from two turtles, the slider (trachemys scripta) and snapper (chelydra serpentina), were compared with those of a human using equilibrium dialysis. the purified t4 binding protein (tbp) from t. scripta had a high affinity that was lower by about fivefold than that of human tbg (3.2 x 10(9) vs 1.7 x 10(10) m-1). the affinity of t4 binding by tbp was similar to that determined for whole plasma from this species ... | 1993 | 8504925 |
| motor pool organization of the external gastrocnemius muscle in the turtle, pseudemys (trachemys) scripta elegans. | the spinal cord of the adult turtle, pseudemys (trachemys) scripta elegans, is now considered a promising model for the study of the segmental motor system in the generalized tetrapod. to facilitate such studies we have examined the location, soma geometry, soma size, and number of motoneurons innervating the external gastrocnemius (eg) muscle in this species, as this muscle is ideally suited to the study of interrelations between the neuronal and muscular components of the segmental motor syste ... | 1996 | 8568906 |