| terminations of primary afferents on lumbar motoneurons in the turtle pseudemys scripta elegans. | the existence of monosynaptic contacts between primary afferents and motoneurons in the lumbar spinal cord of the turtle pseudemys scripta elegans was demonstrated by intracellular injections of horseradish peroxidase. three afferent-motoneuron combinations were satisfactorily labeled and revealed 1, 4 and 6 contacts respectively. all contacts were made on the dorsal dendritic tree of the motoneurons. it is suggested that the contacting primary afferents are from muscle spindles. | 1985 | 4027610 |
| tectoreticular pathways in the turtle, pseudemys scripta. i. morphology of tectoreticular axons. | tectoreticular projections in turtles were examined by reconstructing from serial sections axons that were anterogradely filled with horseradish peroxidase after tectal injections. three tectoreticular pathways each contain extensively collateralized axons. the crossed dorsal pathway (tbd) contains large and small caliber axons. after leaving the tectum, tbd axons emit collaterals into the ipsilateral profundus mesencephali rostralis and then give off a main rostral branch that bears secondary c ... | 1985 | 3980772 |
| morphology of primary afferents to the spinal cord of the turtle pseudemys scripta elegans. | the morphology of primary afferents to the spinal cord of the turtle pseudemys scripta elegans was studied by means of intra-axonal injections of horseradish peroxidase. a total of 74 collaterals arising from 34 different afferents in 22 animals was investigated. within this sample, a division into three morphologically distinct collateral types appeared possible. collaterals of the same parent axon could always be classified to the same type. type a collateral arborizations could be found withi ... | 1985 | 3985359 |
| 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 |
| cerebellar corticonuclear projections in the red-eared turtle pseudemys scripta elegans. | in the present study the organization of the corticonuclear projections of the cerebellum in the red-eared turtle pseudemys scripta elegans was investigated. to find out whether a zonal pattern exists in the cerebellar cortex, a topological analysis was made of the purkinje cell layer of a nissl-stained series of the cerebellum. this analysis showed a distinct, longitudinally oriented zonal pattern of purkinje cells. in each cerebellar half a medial, an intermediate, and a lateral zone could be ... | 1983 | 6304155 |
| 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 |
| 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 |
| 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 |
| spinocerebellar projections in the turtle. observations on their origin and terminal organization. | spinocerebellar projections were studied in the turtle, pseudemys scripta elegans, by both anterograde (injections of 35s-methionine into various spinal segments) and retrograde (injections of horseradish peroxidase into the cerebellar cortex) tracing techniques. after unilateral hrp injections, labeled neurons were found on both sides of the spinal cord. the total number of retrogradely labeled spinocerebellar tract neurons was relatively small and neuronal aggregations were not observed. most ... | 1983 | 6201378 |
| 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 |
| 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 |
| 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 |
| 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 |
| nucleus laminaris of the torus semicircularis: projection to spinal cord in reptiles. | neurons in nucleus laminaris of the torus semicircularis were retrogradely labeled following application of horseradish peroxidase (hrp) to the cervical spinal cord in two lizards (gekko gecko and iguana iguana) and a turtle (pseudemys scripta). different patterns of cell labeling were seen among the species studied and may be related to the distinctive differences in head and body movements seen in these animals during defensive, aggressive and social behaviors. | 1981 | 6270598 |
| 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 |
| 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 |
| 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 |
| 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 |
| multidrug-resistant salmonella enterica serovar typhimurium monophasic variant 4,12:i:- isolated from asymptomatic wildlife in a catalonian wildlife rehabilitation center, spain. | wildlife can act as long-term asymptomatic reservoirs for zoonotic bacteria, such as salmonella. the prevalence and antimicrobial-susceptibility profiles of salmonella spp. were assessed in 263 cases in wildlife from 22 animal orders from a wildlife rehabilitation center in catalonia (ne spain), september 2013-may 2014. eleven of 263 tested animals were positive for salmonella spp., representing an overall prevalence of 4.2%. prevalences by taxonomic categories were 2% in mammals, 4.7% in birds, ... | 2015 | 25973627 |
| multiplicity of glutamic acid decarboxylases (gad) in vertebrates: molecular phylogeny and evidence for a new gad paralog. | the evolution of chordate glutamic acid decarboxylase (gad; ec 4.1.1.15), a key enzyme in the central nervous system synthesizing the neurotransmitter gamma-amino-butyric acid (gaba) from glutamate, was studied. prior to this study, molecular data of gad had been restricted to mammals, which express two distinct forms, gad65 and gad67. these are the products of separate genes and probably are derived from a common ancestral gad following gene duplication at some point during vertebrate evolution ... | 1999 | 10331265 |
| hypoxia tolerance, nitric oxide, and nitrite: lessons from extreme animals. | among vertebrates able to tolerate periods of oxygen deprivation, the painted and red-eared slider turtles (chrysemys picta and trachemys scripta) and the crucian carp (carassius carassius) are the most extreme and can survive even months of total lack of oxygen during winter. the key to hypoxia survival resides in concerted physiological responses, including strong metabolic depression, protection against oxidative damage and-in air-breathing animals-redistribution of blood flow. each of these ... | 2015 | 25729057 |
| effect of anoxia on the electroretinogram of three anoxia-tolerant vertebrates. | to survive anoxia, neural atp levels have to be defended. reducing electrical activity, which accounts for 50% or more of neural energy consumption, should be beneficial for anoxic survival. the retina is a hypoxia sensitive part of the central nervous system. here, we quantify the in vivo retinal light response (electroretinogram; erg) in three vertebrates that exhibit varying degrees of anoxia tolerance: freshwater turtle (trachemys scripta), epaulette shark (hemiscyllium ocellatum) and leopar ... | 2008 | 18579424 |
| adenosine does not save the heart of anoxia-tolerant vertebrates during prolonged oxygen deprivation. | despite adenosine being regarded as an important signaling molecule capable of coordinating atp supply and demand during periods of oxygen deprivation in anoxia-intolerant mammals, the importance of adenosinergic cardiovascular control in anoxia-tolerant vertebrates is poorly understood. here, we report on adenosinergic cardiovascular control during normoxia and prolonged (hours to days) oxygen deprivation for three vertebrate species tolerant of severe hypoxia/anoxia, the closely related common ... | 2007 | 17433747 |
| identification of five reptile egg whites protein using maldi-tof mass spectrometry and lc/ms-ms analysis. | proteomics of egg white proteins of five reptile species, namely siamese crocodile (crocodylus siamensis), soft-shelled turtle (trionyx sinensis taiwanese), red-eared slider turtle (trachemys scripta elegans), hawksbill turtle (eretmochelys imbricate) and green turtle (chelonia mydas) were studied by 2d-page using ipg strip ph 4-7 size 7 cm and ipg strip ph 3-10 size 24 cm. the protein spots in the egg white of the five reptile species were identified by maldi-tof mass spectrometry and lc/ms-ms ... | 2012 | 22266102 |
| 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 |
| wavelength-dependent temporal properties of retinal horizontal cells in turtles. | electrical responses of luminosity horizontal cells (l cells) to monochromatic stimuli were analyzed by intracellular recordings in the retinas of the freshwater turtle (pseudemys scripta elegans) and of the sea turtle (chelonia mydas mydas). light intensity, duration, and wavelength were varied to assess temporal effects. for a given intensity of monochromatic light, response amplitude increased with stimulus duration until maximum amplitude occurred at a specific duration. this suprathreshold ... | 1990 | 2271453 |
| microspectrophotometric measurements of visual pigments in two species of turtle, pseudemys scripta and chelonia mydas. | | 1971 | 5551491 |
| retinal oil globule counts and distributions in two species of turtles: pseudemys scripta elegans (wied) and chelonia mydas mydas (linnaeus). | | 1970 | 5435015 |
| a mycoplasma species of emydidae turtles in the northeastern usa. | mycoplasma infections can cause significant morbidity and mortality in captive and wild chelonians. as part of a health assessment of endangered bog turtles (glyptemys muhlenbergii) in the northeastern us, choanal and cloacal swabs from these and other sympatric species, including spotted turtles (clemmys guttata), eastern box turtles (terrapene carolina carolina), wood turtles (glyptemys insculpta), and common snapping turtles (chelydra serpentina) from 10 sampling sites in the states (us) of d ... | 2015 | 25574806 |
| dietary exposure of bde-47 and bde-99 and effects on behavior, bioenergetics, and thyroid function in juvenile red-eared sliders (trachemys scripta elegans) and common snapping turtles (chelydra serpentina). | juvenile red-eared sliders (trachemys scripta elegans) and snapping turtles (chelydra serpentina) were fed food dosed with brominated diphenyl ether-47 (bde-47) or bde-99 for 6 mo beginning approximately 9 mo posthatch. during the exposure period, measurements of growth, bioenergetics, and behavior were made; thyroid function and accumulation were quantified postexposure. whole-body concentrations of both congeners were lower in red-eared sliders compared with snapping turtles after 6 mo of expo ... | 2014 | 25210006 |
| substrate color-induced melanization in eight turtle species from four chelonian groups. | background color convergence of prey occurring through local adaptation or phenotypically plastic responses can reduce predation rates by visual predators. we assessed the capacity for substrate color-induced melanization in eight turtle species within the groups chelydridae, emydidae, kinosternidae, and trionychidae by rearing individuals on black or white substrates for 160 days. in all aquatic turtle species, integuments of the head and carapace of the individuals that were reared on a black ... | 2014 | 24993507 |
| experimental exposure of eggs to polybrominated diphenyl ethers bde-47 and bde-99 in red-eared sliders (trachemys scripta elegans) and snapping turtles (chelydra serpentina) and possible species-specific differences in debromination. | polybrominated diphenyl ethers (pbdes) are a bioaccumulative, persistent, and toxic class of flame retardants that can potentially impact turtles in natural habitats via exposure through maternal transfer. to simulate maternal transfer in the present study, pbde congeners bde-47 and bde-99 were topically applied to the eggshell and were allowed to diffuse into the egg contents of the red-eared slider (trachemys scripta elegans) and snapping turtle (chelydra serpentina). eggs were topically dosed ... | 2013 | 23147837 |
| comparative effects of in ovo exposure to sodium perchlorate on development, growth, metabolism, and thyroid function in the common snapping turtle (chelydra serpentina) and red-eared slider (trachemys scripta elegans). | perchlorate is a surface and groundwater contaminant found in areas associated with munitions and rocket manufacturing and use. it is a thyroid-inhibiting compound, preventing uptake of iodide by the thyroid gland, ultimately reducing thyroid hormone production. as thyroid hormones influence metabolism, growth, and development, perchlorate exposure during the embryonic period may impact embryonic traits that ultimately influence hatchling performance. we topically exposed eggs of red-eared slide ... | 2012 | 22871607 |
| comparative shell buffering properties correlate with anoxia tolerance in freshwater turtles. | freshwater turtles as a group are more resistant to anoxia than other vertebrates, but some species, such as painted turtles, for reasons not fully understood, can remain anoxic at winter temperatures far longer than others. because buffering of lactic acid by the shell of the painted turtle is crucial to its long-term anoxic survival, we have tested the hypothesis that previously described differences in anoxia tolerance of five species of north american freshwater turtles may be explained at l ... | 2007 | 17008457 |
| physiological responses to freezing in hatchlings of freeze-tolerant and -intolerant turtles. | freeze tolerance is a complex cold-hardiness adaptation that has independently evolved in a diverse group of organisms, including several ectothermic vertebrates. because little is known about the mechanistic basis for freeze tolerance in reptiles, we compared responses to experimental freezing in winter-acclimatized hatchlings representing nine taxa of temperate north american turtles, including ones that tolerated freezing and others that did not. viability rates of hatchlings frozen to -3 deg ... | 2006 | 16758216 |
| anoxia tolerance and freeze tolerance in hatchling turtles. | freezing survival in hatchling turtles may be limited by ischemic anoxia in frozen tissues and the associated accumulation of lactate and reactive oxygen species (ros). to determine whether mechanisms for coping with anoxia are also important in freeze tolerance, we examined the association between capacities for freezing survival and anoxia tolerance in hatchlings of seven species of turtles. tolerance to freezing (-2.5 degrees c) was high in emydoidea blandingii, chrysemys picta, terrapene orn ... | 2005 | 15739066 |
| survival and behavior of freshwater turtles after rehabilitation from an oil spill. | an oil spill in february 2000 at the john heinz national wildlife refuge in southeastern pennsylvania affected four species of freshwater turtles including painted turtles (chrysemys picta), snapping turtles (chelydra serpentina), red-eared slider turtles (trachemys scripta), and red-bellied turtles (pseudemys rubriventris). in the summer and fall of 2000, there were no differences in survival, home range, and temperature preference of 16 oil exposed/rehabilitated (oer) turtles, 18 possibly expo ... | 2003 | 12927492 |
| cold-hardiness and evaporative water loss in hatchling turtles. | north american turtles hatch in late summer and spend their first winter either on land or underwater. adaptations for terrestrial overwintering of hatchlings in northern regions, where winter thermal and hydric regimes are harsh, have not been systematically investigated in many species. we measured intrinsic supercooling capacity, resistance to inoculative freezing, and desiccation resistance in hatchlings of terrestrial and aquatic turtles collected from northern (terrapene ornata, chrysemys ... | 2008 | 11436135 |
| morphogenesis of the turtle shell: the development of a novel structure in tetrapod evolution. | the turtle shell is an evolutionary novelty that is synapomorphic for chelonians. the carapace is initiated by the entrapment of the ribs by the carapacial ridge (cr), a lateral bulge of the dorsal ectoderm and dermal mesoderm. the mechanisms by which the cr is initiated, the ribs entrapped and the dorsal dermis ossified, remains unknown. similarly, the formation of the plastron remains unexplained. here, we present a series of anatomical investigations into plastron and carapace formation in th ... | 2007 | 11341674 |
| endogenous yolk steroid hormones in turtles with different sex-determining mechanisms. | maternal transfer of nutrients, including steroid hormones, to embryos during gestation in viviparous amniotes is well known, but the concordant process in oviparous amniotes is poorly understood. recent evidence suggests that steroid hormones are present in freshly laid eggs of archosaurs and that their concentrations may influence offspring phenotypes. this process might be especially important in reptiles with temperature-dependent sex determination (tsd), because embryonic sex determination ... | 1998 | 9707477 |
| purification and partial amino acid sequences of two distinct albumins from turtle plasma. | two putative albumins, denoted alb-1 (apparent molecular mass of 67 kda) and alb-2 (68 kda), were purified from plasma of the emydid turtle (trachemys scripta). concentrations in serum or plasma were determined by radioimmunoassay using 125i-labeled alb-1. in juvenile turtles (less than 2 years of age), serum concentrations of alb-1 and alb-2 were 2.72 +/- 0.23 mg/ml and 1.68 +/- 0.22 mg/ml, respectively, while concentrations in plasma pooled from adult turtles were 4.2 mg/ml and 2.6 mg/ml, resp ... | 1997 | 9440230 |
| abundant synthesis of transthyretin in the brain, but not in the liver, of turtles. | the binding of thyroxine to proteins in the blood plasma of the turtle, trachemys scripta, was analyzed by incubation with radioactive thyroxine, electrophoresis and autoradiography. albumin and an alpha-globulin were found to bind thyroxine; no thyroxine-binding transthyretin was detected in the prealbumin region. in contrast to blood plasma, a thyroxine-binding prealbumin was observed in medium from t. scripta choroid plexus incubated in vitro. rna was extracted from brain tissue containing ch ... | 1997 | 9253180 |
| electron microscopy of golgi-impregnated photoreceptors reveals connections between red and green cones in the turtle retina. | red and green cones of two turtle species (pseudemys scripta elegans and chelydra serpentina) retina have been stained with golgi procedures and examined by light microscopy of whole-mount tissue and by electron microscopy of serial thin sections. by light microscopy, red and green single cones appear indistinguishable, but double cones can be readily identified. all golgi-stained photoreceptors in turtle retina have a spray of telodendria radiating from their synaptic pedicles. the telodendria ... | 1985 | 4031990 |
| 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 |
| pituitary regulation of appetite and growth in the turtles pseudomys scripta elegans and chelydra serpentina. | | 1974 | 4813415 |
| formation of the chondrocranium of trachemys scripta (reptilia: testudines: emydidae) and a comparison with other described turtle taxa. | few descriptions of the formation of the chelonian chondrocranium exist. herein, developmental stages critical to the formation of the chondrocranium of the red-eared slider, trachemys scripta (testudines: emydidae), are described and illustrated, with particular attention given to ontogenetic changes that take place in the orbitotemporal region of the skull. morphological descriptions are based on cleared and double-stained and serially-sectioned embryos. these specimens allowed for a detailed ... | 2007 | 17236189 |
| forelimb kinematics during swimming in the pig-nosed turtle, carettochelys insculpta, compared with other turtle taxa: rowing versus flapping, convergence versus intermediacy. | animals that swim using appendages do so by way of rowing and/or flapping motions. often considered discrete categories, rowing and flapping are more appropriately regarded as points along a continuum. the pig-nosed turtle, carettochelys insculpta, is unusual in that it is the only freshwater turtle to have limbs modified into flippers and swim via synchronous forelimb motions that resemble dorsoventral flapping, traits that evolved independently from their presence in sea turtles. we used high- ... | 2013 | 23125335 |
| ultrastructure of the dorsal lateral geniculate complex in turtles of the genera pseudemys and chrysemys. | the ultrastructure of the dorsal lateral geniculate complex in the turtles pseudemys scripta elegans and chrysemys picta belli has been studied. the majority of neurons have somata situated in a cell plate that forms the medial face of the complex. relatively few synaptic contacts occur on the somata of cell plate neurons, but three types of axon terminals contact their proximal dendrites as they course through the cell plate. the most frequent are terminals with clear, round synaptic vesicles t ... | 1986 | 3594200 |
| the viability of nearctic freshwater turtles submerged in anoxia and normoxia at 3 and 10 degrees c. | survival times of temperature-acclimated freshwater turtles submerged in normoxic and anoxic water were determined. juvenile chrysemys scripta from alabama and adult chrysemys picta bellii from wisconsin exhibited the maximal survival times of the 10 species and subspecies investigated, both being able to survive at least a half-year of submergence at 3 degrees c in normoxic water. minimal viability was exhibited by sternotherus odoratus and trionyx spiniferus submerged in anoxia at 10 degrees c ... | 1985 | 2863050 |
| visual cortex in a reptile, the turtle (pseudemys scripta and chrysemys picta). | | 1977 | 884523 |
| the effects of induced cold torpor and time of year on blood coagulation in pseudemys scripta elegans and chrysemys picta belli. | | 1975 | 236129 |
| forelimb muscle function in pig-nosed turtles, carettochelys insculpta: testing neuromotor conservation between rowing and flapping in swimming turtles. | changes in muscle activation patterns can lead to new locomotor modes; however, neuromotor conservation-the evolution of new forms of locomotion through changes in structure without concurrent changes to underlying motor patterns-has been documented across diverse styles of locomotion. animals that swim using appendages do so via rowing (anteroposterior oscilations) or flapping (dorsoventral oscilations). yet few studies have compared motor patterns between these swimming modes. in swimming turt ... | 2013 | 23966596 |
| comparison between oogenesis and related ovarian structures in a reptile, pseudemys scripta elegans (turtle) and in a bird coturnix coturnix japonica (quail). | the aspect of the oogonia during their premitotic dna synthesis and of the premeiocytes during their premeiotic dna synthesis was studied in turtles by autoradiography, after injection of 3h-thymidine. as in the adult laying quail, the intrafollicular oocytes of the adult turtle go through three successive stages: prelampbrush, lampbrush and postlampbrush. during the prelampbrush and lampbrush stage two kinds of nucleoli exist: peripheral and central. in contrast to avian yolk, during its final ... | 2006 | 9269708 |
| extensive homology of chicken macrochromosomes in the karyotypes of trachemys scripta elegans and crocodylus niloticus revealed by chromosome painting despite long divergence times. | we report extensive chromosome homology revealed by chromosome painting between chicken (gallus gallus domesticus, gga, 2n = 78) macrochromosomes (representing 70% of the chicken genome) and the chromosomes of a turtle, the red-eared slider (trachemys scripta elegans, tsc, 2n = 50), and the nile crocodile (crocodylus niloticus, cni, 2n = 32). our data show that gga1-8 arms seem to be conserved in the arms of tsc chromosomes, gga1-2 arms are separated and homologous to cni1p, 3q, 4q and 5q. in ad ... | 2012 | 22572532 |
| reassessment of genome size in turtle and crocodile based on chromosome measurement by flow karyotyping: close similarity to chicken. | the genome size in turtles and crocodiles is thought to be much larger than the 1.2 gb of the chicken (gallus gallus domesticus, gga), according to the animal genome size database. however, gga macrochromosomes show extensive homology in the karyotypes of the red eared slider (trachemys scripta elegans, tsc) and the nile crocodile (crocodylus niloticus, cni), and bird and reptile genomes have been highly conserved during evolution. in this study, size and gc content of all chromosomes are measur ... | 2012 | 22491763 |
| vascular distensibilities have minor effects on intracardiac shunt patterns in reptiles. | the different vascular distensibilities of systemic and pulmonary circuits were recently proposed as an important mechanism defining the direction of cardiac shunt and the distribution of cardiac output in vertebrates with undivided cardiac ventricles. in short, the more distensible pulmonary vascular bed was proposed to accommodate a larger portion of the blood ejected from the heart when cardiac output increases. to evaluate this hypothesis, we performed a meta-analysis based on fourteen previ ... | 2017 | 28390664 |
| brain na+/k+-atpase activity in two anoxia tolerant vertebrates: crucian carp and freshwater turtle. | the crucian carp (carassius carassius) and freshwater turtles (trachemys scripta) are among the very few vertebrates that can survive extended periods of anoxia. the major problem for an anoxic brain is energy deficiency. in the brain, the na+/k+-atpase is the single most atp consuming enzyme, being responsible for maintaining ion gradients. we here show that the na+/k+-atpase activity in the turtle brain is reduced by 31% in telencephalon and by 34% in cerebellum after 24 h of anoxia. both chan ... | 1997 | 9389603 |
| nitric oxide metabolites during anoxia and reoxygenation in the anoxia-tolerant vertebrate trachemys scripta. | moderate elevations of nitrite and nitric oxide (no) protect mammalian tissues against ischemia (anoxia)-reperfusion damage by inhibiting mitochondrial electron transport complexes and reducing the formation of reactive oxygen species (ros) upon reoxygenation. crucian carp appear to exploit this mechanism by upregulating nitrite and other nitrite/no metabolites (s-nitroso and iron-nitrosyl compounds) in several tissues when exposed to anoxia. we investigated whether this is a common strategy amo ... | 2014 | 24143029 |
| 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 |
| alleviating brain stress: what alternative animal models have revealed about therapeutic targets for hypoxia and anoxia. | while the mammalian brain is highly dependent on oxygen, and can withstand only a few minutes without air, there are both vertebrate and invertebrate examples of anoxia tolerance. one example is the freshwater turtle, which can withstand days without oxygen, thus providing a vertebrate model with which to examine the physiology of anoxia tolerance without the pathology seen in mammalian ischemia/reperfusion studies. insect models such as drosophila melanogaster have additional advantages, such a ... | 2013 | 25264428 |
| sex reversal in reptiles: reproductive oddity or powerful driver of evolutionary change? | is sex a product of genes, the environment, or both? in this review, we describe the diversity of sex-determining mechanisms in reptiles, with a focus on systems that display gene-environment interactions. we summarise the field and laboratory-based evidence for the occurrence of environmental sex reversal in reptiles and ask whether this is a widespread evolutionary mechanism affecting the evolution of sex chromosomes and speciation in vertebrates. sex determination systems exist across a conti ... | 2016 | 27794577 |
| first reported outbreak of severe spirorchiidiasis in emys orbicularis, probably resulting from a parasite spillover event. | the importance of disease-mediated invasions and the role of parasite spillover as a substantial threat to the conservation of global biodiversity are now well known. although competition between invasive sliders trachemys scripta elegans and indigenous european turtles has been extensively studied, the impact of this invasive species on diseases affecting native populations is poorly known. during winter 2012-2013 an unusual event was detected in a population of emys orbicularis (linnaeus, 1758 ... | 2015 | 25667339 |
| invasive species threat: parasite phylogenetics reveals patterns and processes of host-switching between non-native and native captive freshwater turtles. | one of the major threats to biodiversity involves biological invasions with direct consequences on the stability of ecosystems. in this context, the role of parasites is not negligible as it may enhance the success of invaders. the red-eared slider, trachemys scripta elegans, has been globally considered among the worst invasive species. since its introduction through the pet trade, t. s. elegans is now widespread and represents a threat for indigenous species. because t. s. elegans coexists wit ... | 2011 | 21767431 |
| in situ cardiac perfusion reveals interspecific variation of intraventricular flow separation in reptiles. | the ventricles of non-crocodilian reptiles are incompletely divided and provide an opportunity for mixing of oxygen-poor blood and oxygen-rich blood (intracardiac shunting). however, both cardiac morphology and in vivo shunting patterns exhibit considerable interspecific variation within reptiles. in the present study, we develop an in situ double-perfused heart approach to characterise the propensity and capacity for shunting in five reptile species: the turtle trachemys scripta, the rock pytho ... | 2016 | 27207643 |
| 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 |
| epigenetic control of gonadal aromatase (cyp19a1) in temperature-dependent sex determination of red-eared slider turtles. | in the red-eared slider turtle (trachemys scripta), a species with temperature-dependent sex determination (tsd), the expression of the aromatase gene during gonad development is strictly limited to the female-producing temperature. the underlying mechanism remains unknown. in this study, we identified the upstream 5'-flanking region of the aromatase gene, gonad-specific promoter, and the temperature-dependent dna methylation signatures during gonad development in the red-eared slider turtle. th ... | 2013 | 23762231 |
| the cloning and expression analysis of lhx9 during gonadal sex differentiation in the red-eared slider turtle, trachemys scripta, a species with temperature-dependent sex determination. | many reptiles, including the red-eared slider turtle (trachemys scripta), possess a temperature-dependent sex determination (tsd) mechanism where the temperature at which the developing embryos are incubated dictates the gonadal sex of the animal. a number of mammalian gene orthologues have been identified in the sex determination/differentiation cascade of reptiles with tsd although the exact trigger(s) is not well understood. a potential early regulator of gonadal differentiation, lhx9, contro ... | 2013 | 23671035 |
| spermiogenesis in the red-ear turtle (pseudemys scripta) and the domestic fowl (gallus domesticus): a study of cytoplasmic events including cell volume changes and cytoplasmic elimination. | nuclear and cytoplasmic volume changes as well as the elimination of residual spermatid cytoplasm were investigated in the red-ear turtle (pseudemys scripta) and the rooster (gallus domesticus). nuclei of newly formed spermatids which were originally centrally located became eccentrically located within the cell in both species. shortly thereafter the nuclear pole of the spermatid was found situated within deep crypts of a sertoli cell. the cytoplasm of elongating spermatids was displaced along ... | 1988 | 3199450 |
| toxicokinetics of selenium in the slider turtle, trachemys scripta. | selenium (se) is an essential element that can be harmful for wildlife. however, its toxicity in poikilothermic amniotes, including turtles, remains poorly investigated. the present study aims at identifying selenium toxicokinetics and toxicity in juvenile slider turtles (age: 7 months), trachemys scripta, dietary exposed to selenium, as selenomethionine semet, for eight weeks. non-destructive tissues (i.e. carapace, scutes, skin and blood) were further tested for their suitability to predict se ... | 2016 | 26939937 |
| myxidium scripta n. sp. identified in urinary and biliary tract of louisiana-farmed red-eared slider turtles trachemys scripta elegans. | during a necropsy investigation of a mortality event occurring at a turtle farm in assumption parish, louisiana, spores of a myxozoan were identified in the renal tubules in 3 of 6, the gall bladder lumen in 2 of 6, and the bile ductule in 1 of 6 red eared slider turtles trachemys scripta elegans. in total, myxozoa were identified in 4 of 6 turtles. in 1 turtle, renal tubules contained numerous mature spores, had epithelial hyperplasia, granulomatous transformation, compression of adjacent tubul ... | 2008 | 18814545 |
| 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 |
| eimeria scriptae n. sp. (sporozoa: eimeriidae) from the red-eared turtle pseudemys scripta elegans. | | 1969 | 5387948 |
| identification and localization of gonadotropin-inhibitory hormone (gnih) orthologs in the hypothalamus of the red-eared slider turtle, trachemys scripta elegans. | gonadotropin-inhibitory hormone (gnih) was discovered in 2000 as a novel hypothalamic neuropeptide that inhibited gonadotropin release in the japanese quail. gnih and its orthologs have a common c-terminal lpxrfamide (x=l or q) motif, and have been identified in vertebrates from agnathans to humans, apart from reptiles. in the present study, we characterized a cdna encoding gnih orthologs in the brain of the red-eared slider turtle. the deduced precursor protein consisted of 205 amino-acid resid ... | 2016 | 26130239 |
| reference values for the production of the aqueous fraction of the tear film measured by the standardized endodontic absorbent paper point test in different exotic and laboratory animal species. | the aqueous fraction of the tear film and the horizontal palpebral fissure length (hpfl) were measured in exotic and laboratory animals, specifically saffron finches (sicalis flaveola), chestnut-bellied seed-finches (sporophila angolensis), red-eared sliders (trachemys scripta elegans), rats (rattus norvegicus) and mice (mus musculus). these species possess small eyes making it difficult to perform the typical schirmer tear test. measurement of the aqueous fraction of the tear was performed usin ... | 2014 | 23464753 |
| efferent innervation of turtle semicircular canal cristae: comparisons with bird and mouse. | in the vestibular periphery of nearly every vertebrate, cholinergic vestibular efferent neurons give rise to numerous presynaptic varicosities that target hair cells and afferent processes in the sensory neuroepithelium. although pharmacological studies have described the postsynaptic actions of vestibular efferent stimulation in several species, characterization of efferent innervation patterns and the relative distribution of efferent varicosities among hair cells and afferents are also integr ... | 2015 | 25560461 |
| species recognition of congeneric acanthocephalans in slider turtles by random-amplified polymorphic dna (rapd) markers. | species recognition of acanthocephalans of the genus neoechinorhynchus (hamann, 1892) found in the freshwater turtle trachemys scripta (wied, 1838) has previously been based primarily on female body and egg morphology. observed morphological plasticity within and among species may lead to the misclassification of female specimens and leaves males of different species completely indistinguishable. here, random-amplified polymorphic dna (rapd) analysis was used to genetically characterize samples ... | 1998 | 9714226 |
| detection of mycoplasma spp., herpesviruses, topiviruses, and ferlaviruses in samples from chelonians in europe. | we tested samples from 1,015 chelonians in europe for mycoplasma spp., herpesviruses, ranaviruses, picornaviruses, and ferlaviruses by pcr. mycoplasma spp. were detected in 42.1% and herpesviruses were detected in 8.0% of tested chelonians. differentiation of the herpesviruses revealed that 46.9% of the detected chelonian viruses were testudinid herpesvirus 1 (tehv-1) and 54.3% were tehv-3, including co-detections of tehv-1 and -3 in 3 tortoises. tehv-4 was detected in a leopard tortoise ( stigm ... | 2017 | 28754074 |
| sex determination: where environment and genetics meet. | in mammals and birds the genetic constitution established at the time of fertilization determines the type of gonad that develops, whereas in all crocodilians and many turtles it is the temperature experienced during the mid-trimester of embryogenesis that initiates gonadal differentiation. research with the red-eared slider suggests considerable conservation in the genetic cascades that underlie the sex determination process in vertebrates and, further, that the patterns of expression of these ... | 2010 | 12492409 |
| 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 |
| tracking the evolution of the proenkephalin gene in tetrapods. | in gnathostomes there is remarkable consistency in the organization of the proenkephalin gene. this opioid precursor encodes seven opioid (yggf) sequences: five pentapeptide sequences, a met-enkephalin-7 sequence and a met-enkephalin-8 sequence. yet, within vertebrate lineages there can be distinct sets of pentapeptide opioids (yggfm or yggfl). in the sarcopterygii, the sixth opioid position in lungfishes and anuran amphibian proenkephalin genes encodes a met-enkephalin (yggfm) sequence. however ... | 2007 | 17449037 |
| evolution of neurotransmitter-related markers in the vertebrate telencephalon. comparative microchemical study in discrete brain regions of a frog and a turtle. | 1. neurochemical markers related to cholinergic, gabaergic and glutamatergic/aspartatergic neurotransmission have been measured in telencephalic areas obtained by microdissection from frog (rana esculenta) and turtle (pseudemys scripta elegans) brain. 2. in both species, pallial areas showed remarkably higher levels of synaptosomal d-3h-aspartate high affinity uptake than basal regions. conversely, striatal and septal areas possessed higher levels of the gabaergic marker glutamate decarboxylase ... | 1988 | 2899002 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| slow atp loss and the defense of ion homeostasis in the anoxic frog brain. | for most vertebrates, cutting off the oxygen supply to the brain results in a rapid (within minutes) loss of atp, the failure of atp-dependent ion-transport process, subsequent anoxic depolarization of neuronal membrane potential and consequential neuronal death. the few species that survive brain anoxia for days or months, such as the freshwater turtle trachemys scripta, avoid anoxic depolarization and maintain brain atp levels through a coordinated downregulation of brain energy demand process ... | 2001 | 11707503 |
| animal response to drastic changes in oxygen availability and physiological oxidative stress. | oxygen is essential for most life forms, but it is also inherently toxic due to its biotransformation into reactive oxygen species (ros). in fact, the development of many animal and plant pathological conditions, as well as natural aging, is associated with excessive ros production and/or decreased antioxidant capacity. however, a number of animal species are able to tolerate, under natural conditions, situations posing a large potential for oxidative stress. situations range from anoxia in fish ... | 2002 | 12458182 |
| reptiles and amphibians as potential reservoir hosts of chikungunya virus. | chikungunya virus is an emerging arbovirus of significant human-health concern. little is known about its sylvatic cycle, including whether ectothermic vertebrates are permissive to infection. in this study, individuals from ten species of reptiles and amphibians were inoculated with chikungunya virus and samples of blood were tested to characterize viremia and seroconversion. viremia was not detected in cane toads, house geckos, or american alligators, but most of the green iguanas, red-eared s ... | 0 | 29313469 |
| localization of insulin to gastroenteropancreatic cells in the turtle gastrointestinal tract. | insulin has been localized immunocytochemically to open-type gastroenteropancreatic endocrine cells in sections of bouin's-fixed upper, middle, and lower intestine from chrysemys picta, pseudemys scripta scripta, p. scripta elegans, p. floridana, sternotherus odoratus, and trionyx spinifer asper. radioimmunoassay of extracts of mucosal scrapings from chrysemys intestine indicates differential amounts of insulin-like immunoreactivity within the intestine (higher amounts in the lower intestine) an ... | 1990 | 2185121 |
| neurotensin is localized to paracrine cells in the urinary bladder of the turtle, chrysemys picta. | urinary bladder from the painted turtle, chrysemys picta, contains a substantial population of endocrine/paracrine cells scattered through the mucosal epithelium which immunostains using antisera directed toward mammalian neurotensin (nt). radiommunoassay of 0.1 n hcl extracts of chrysemys bladder indicated an immunoreactive nt (int) concentration of 161 +/- 39 pmol/g tissue (n = 9), an amount lower but comparable in magnitude to that found in mucosal scrapings of the intestine (926 +/- 125 pmol ... | 1990 | 2202609 |
| 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 |
| 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 |
| anoxia-induced gene expression in turtle heart. upregulation of mitochondrial genes for nadh-ubiquinone oxidoreductase subunit 5 and cytochrome c oxidase subunit 1. | a cdna library constructed from heart of anoxia-exposed adult turtles (trachemys scripta elegans) was differentially screened with 32p-labeled single-stranded cdna probes from heart of control versus anoxic animals to clone genes induced by anoxia stress. four cdna clones, pbtar20, pbtar34, pbtar63 and pbtar914 were obtained and confirmed to be upregulated in response to anoxic submergence (20 h in n2-bubbled water at 7 degrees c). two clones, pbtar20 and pbtar63, were characterized by sequence ... | 1996 | 8898892 |
| comparative gene expression of steroidogenic factor 1 in chrysemys picta and apalone mutica turtles with temperature-dependent and genotypic sex determination. | characterizing the molecular network underlying temperature-dependent (tsd) and genotypic (gsd) sex determination, including patterns across closely related taxa, is crucial to elucidate the still enigmatic evolution of sex determining mechanisms in vertebrates. here we examined the expression of an important gene for sexual differentiation common to both systems, sf1, at male- and female-producing temperatures, in tsd (chrysemys picta) and gsd turtles (apalone mutica). we tested the hypotheses ... | 2010 | 16925678 |
| experimental test of the effects of fluctuating incubation temperatures on hatchling phenotype. | in the painted turtle (chrysemys picta) and red-eared slider turtle (trachemys scripta), the temperature that eggs are exposed to during incubation determines the sex of the developing embryo. constant temperature incubation experiments have shown that for each of these species there is a pivotal temperature that produces a 1:1 sex ratio; higher temperatures bias sex ratios toward females, and lower temperatures toward males. few studies have examined how fluctuating temperatures, as would be ex ... | 2007 | 17377950 |
| effect of cadmium on gonadal development in freshwater turtle (trachemys scripta, chrysemys picta) embryos. | prior studies on painted turtle (chrysemys picta) sub-populations near the massachusetts military reservation (mmr), a superfund site on cape cod, massachusetts, usa, suggest several reproductive deficits which may be related to xenobiotics. several heavy metals, including cadmium, have been detected in cape cod surface water and sediments. the present study was carried out to investigate the effect of an environmentally relevant dose of cadmium on gonadal development during the end of the germ ... | 2008 | 18205057 |
| living at extremes: development at the edges of viable temperature under constant and fluctuating conditions. | in the painted turtle (chrysemys picta) and the red-eared slider (trachemys scripta), the temperature that eggs are exposed to during incubation influences many traits of the developing embryo. we tested the effect of fluctuating- versus constant-temperature incubation regimes at the high and low ends of the viable developmental temperature range to assess the effect of incubation environment on offspring development. eggs were incubated in four treatments: 23 degrees c constant, 23 degrees +/- ... | 2009 | 19199555 |
| winter severity and phenology of spring emergence from the nest in freshwater turtles. | although many species of freshwater turtles emigrate to water soon after hatching, the offspring of some species overwinter on land and move to aquatic habitats in the following spring. timing of emigration can affect the hatchlings' fitness, but the factors underlying phenology of nest emergence are incompletely understood. we tested the supposition that cold stress imposed during hibernation can influence the timing of nest emergence in three species of turtles in the central usa. in each year ... | 2010 | 20467723 |
| cloning of estrogen receptor alpha and aromatase cdnas and gene expression in turtles (chrysemys picta and pseudemys scripta) exposed to different environments. | reproductive changes have been observed in painted turtles (chrysemys picta) from a site with known contamination located on cape cod, ma, usa. we hypothesize that these changes are caused by exposure to endocrine-disrupting compounds and that genes playing a significant role in reproduction are affected. cdna sequences were determined for estrogen receptor alpha and aromatase in the painted turtle. these genes were measured in our study animals using quantitative pcr. adult turtles were trapped ... | 2011 | 21664488 |