Publications

population coding of motion patterns in the early visual system.	using extracellular recordings and computational modeling, we study the responses of a population of turtle (pseudemys scripta elegans) retinal ganglion cells to different motion patterns. the onset of motion of a bright bar is signaled by a rise of the population activity that occurs within less than 100 ms. correspondingly, more complex stimulus movement patterns are reflected by rapid variations of the firing rate of the retinal ganglion cell population. this behavior is reproduced by a compu ...	2001	11730302
bafilomycin a1 at nanomolar concentrations saturably inhibits a portion of turtle bladder acidification current.	an earlier report indicated that acid secretion in turtle urinary bladder is driven by an unusual vacuolar h+-atpase and that the atpase accounts for essentially all acid secreted. these results, however, are difficult to reconcile with the acid transporters currently ascribed to the renal collecting duct. here, we re-examine the effect of bafilomycin a1, an inhibitor of vacuolar (v-type) h+-atpases, on acid secretion by intact isolated bladders from pseudemys scripta turtles. serosal-side bafil ...	2001	11683444
development of an evolutionarily novel structure: fibroblast growth factor expression in the carapacial ridge of turtle embryos.	the turtle shell, an evolutionarily novel structure, contains a bony exoskeleton that includes a dorsal carapace and a ventral plastron. the development of the carapace is dependent on the carapacial ridge (cr), a bulge in the dorsal flank that contains an ectodermal structure analogous to the apical ectodermal ridge (aer) of the developing limb (burke. 1989a. j morphol 199:363-378; burke. 1989b. fortschr zool 35:206-209). although the cr is thought to mediate the initiation and outgrowth of the ...	2001	11598915
embryonic exposure to low-dose pesticides: effects on growth rate in the hatchling red-eared slider turtle.	in the red-eared slider turtle, pesticides can alter expected sex outcomes, a major step in the inferred pathway of sex determination, and hatchling steroid physiology. changes such as these can profoundly affect an organism's fitness. other potential markers for effects on fitness include hatchling mass, hatchling use of maternal stores (residual yolk), and especially early hatchling growth rates. in the current study, red-eared slider turtles were exposed during embryogenesis to one of three c ...	2001	11594703
reductions in systemic oxygen delivery induce a hypometabolic state in the turtle trachemys scripta.	we investigated the effects of vagal reductions in o(2) delivery on oxygen consumption (vo(2)) in the anesthetized freshwater turtle trachemys scripta. specifically, these experiments tested the hypothesis that reductions in arterial oxygen partial pressure (po(2)) and/or systemic oxygen transport (sot) trigger a metabolic downregulation. during electric stimulation of the efferent branch of the sectioned right vagus nerve (rvef), systemic cardiac output decreased 60-70%, systemic po(2) fell by ...	2001	11557639
accumulation and selective maternal transfer of contaminants in the turtle trachemys scripta associated with coal ash deposition.	coal combustion wastes are enriched in a number of potentially toxic compounds and may pose risks to biota exposed to the wastes. slider turtles (trachemys scripta) are common inhabitants of coal ash settling basins in south carolina, usa, where they feed on contaminated prey items and accumulate high levels of potentially toxic compounds in their tissues. furthermore, female sliders sometimes nest in contaminated spill piles and thus may expose embryos to contaminated soils. we examined two pot ...	2001	11525496
ultraviolet colour opponency in the turtle retina.	we have examined the functional architecture of the turtle pseudemys scripta elegans retina with respect to colour processing, extending spectral stimulation into the ultraviolet, which has not been studied previously in the inner retina. we addressed two questions. (i) is it possible to deduce the ultraviolet cone spectral sensitivity function through horizontal cell responses? (ii) is there evidence for tetrachromatic neural mechanisms, i.e. uv/s response opponency? using a constant response m ...	2001	11511668
medetomidine-ketamine anesthesia in red-eared slider turtles (trachemys scripta elegans).	this study evaluated the effects of high and low dosages of medetomidine-ketamine in red-eared slider turtles (trachemys scripta elegans) and the reversibility of the anesthesia with atipamezole. thirty healthy adult turtles were assigned randomly to one of two dosage groups. the lower dosage group received 0.1 mg medetomidine/kg body weight intramuscularly (i.m.) combined with 5 mg ketamine/kg i.m. the higher dosage group received 0.2 mg medetomidine/kg i.m. combined with 10 mg ketamine/kg i.m. ...	2001	11353517
oxygen binding by single red blood cells from the red-eared turtle trachemys scripta.	oxygen-binding properties of single red blood cells from the red-eared turtle trachemys scripta were measured by microspectrophotometry to describe the variation in oxygen affinity of red blood cells and to gain insight into the distribution of functionally different hemoglobins among red blood cells. methodologically, this study represents the first report on the cell-to-cell variation in oxygen-binding properties based on oxygen-binding curves of single vertebrate red blood cells. the cells di ...	2001	11299255
an immunohistochemical study on the endocrine cells in the alimentary tract of the red-eared slider (trachemys scripta elegans).	the regional distribution and relative frequency of endocrine cells in the alimentary tract of the red-eared slider, trachemys scripta elegans, were investigated by immunohistochemical methods using 10 antisera. most of the immunoreactive cells in the intestine were spherical or spindle-like in shape (open-type cells), while round cells (closed-type cells) were occasionally found in the stomach. these immunoreactive cells were located in the basal portion of the intestine, including the oesophag ...	2001	11284161
estradiol and incubation temperature modulate regulation of steroidogenic factor 1 in the developing gonad of the red-eared slider turtle.	red-eared slider turtles are genetically bipotential for sex determination, with incubation temperature of the egg determining gonadal sex. at higher incubation temperatures, females are produced, possibly due to increased biosynthesis of estrogen. exogenous estrogen causes the formation of ovaries, and prevention of estrogen biosynthesis results in the development of testes. in mammals, steroidogenic factor 1 (sf-1) regulates most genes required for estrogen biosynthesis from cholesterol. in ma ...	2001	11250919
effects of high extracellular [k+] and adrenaline on force development, relaxation and membrane potential in cardiac muscle from freshwater turtle and rainbow trout.	increases in extracellular k(+) concentrations reduced the twitch force amplitude of heart muscle from the freshwater turtle (trachemys scripta elegans) and rainbow trout (oncorhynchus mykiss). adrenaline augmented twitch force amplitude and reduced the relative influence of [k(+)]. in the absence of adrenaline, high [k(+)] had less effect in reducing twitch force in turtle than in trout, whereas the reverse was true in the presence of adrenaline. under anoxic conditions, twitch force was lower ...	2001	11136612
chromosome translocations in t. scripta: the dose-rate effect and in vivo lymphocyte radiation response.	using a whole-chromosome fish painting probe we previously developed for chromosome 1 of the yellow-bellied slider turtle (trachemys scripta), we investigated the dose-rate effect for radiation-induced symmetrical translocations in t. scripta fibroblasts and lymphocytes. the dose rate below which no reduction in effect per unit dose is observed with further dose protraction was approximately 23 cgy h(-1). we estimated the whole-genome spontaneous background level of complete, apparently simple s ...	2001	11121217
conservation of chromosome 1 in turtles over 66 million years.	fluorescence in situ hybridization of a whole chromosome 1-specific probe from the yellow-bellied slider turtle (trachemys scripta) to cells from four other species of turtle ranging from a desert tortoise to a loggerhead sea turtle resulted in specific and exclusive hybridization to chromosome 1 in all five species. previous observations of conservation in the giemsa banding pattern and chromosome morphology and number among turtles are thus extended to the dna sequence level, revealing a cytog ...	2001	11306813
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
complete suppression of protein synthesis during anoxia with no post-anoxia protein synthesis debt in the red-eared slider turtle trachemys scripta elegans.	two previous studies of the effects of anoxia on protein synthesis in anoxia-tolerant turtles (trachemys scripta elegans, chrysemys picta bellii) have generated opposing results. using the flooding-dose method, we measured the rate of protein synthesis following injection and incorporation of a large dose of radiolabelled phenylalanine to resolve the question of whether anoxia results in a downregulation of protein synthesis. after 1 h of anoxia, levels of protein-incorporated radiolabel indicat ...	2001	11815659
concentrations of steroid hormones in layers and biopsies of chelonian egg yolks.	the actions of circulating hormones, although relatively well understood for adults, are largely unknown for their developing embryos. transfer of maternal hormones to the egg is known to occur in oviparous species, and recently the presence of hormonally heterogeneous yolk layers has been described in two avian species. to investigate the possibility of a similar phenomenon occurring in chelonian species, egg yolk layers were analyzed in the painted turtle (chrysemys picta marginata) and the re ...	2001	11161774
comparative kinematics of the forelimb during swimming in red-eared slider (trachemys scripta) and spiny softshell (apalone spinifera) turtles.	softshell turtles (family trionychidae) possess extensive webbing between the digits of the manus, suggesting that the forelimb may serve as an effective thrust generator during aquatic locomotion. however, the hindlimb has previously been viewed as the dominant propulsive organ in swimming freshwater turtles. to evaluate the potential role of the forelimb in thrust production during swimming in freshwater turtles, we compared the forelimb morphology and three-dimensional forelimb kinematics of ...	2001	11606600
acute and chronic influence of temperature on red blood cell anion exchange.	unidirectional (36)cl(-) efflux via the red blood cell anion exchanger was measured under cl(-) self-exchange conditions (i.e. no net flow of anions) in rainbow trout oncorhynchus mykiss and red-eared freshwater turtle trachemys scripta to examine the effects of acute temperature changes and acclimation temperature on this process. we also evaluated the possible adaptation of anion exchange to different temperature regimes by including our previously published data on other animals. an acute tem ...	2001	11104709
pseudoknots in prion protein mrnas confirmed by comparative sequence analysis and pattern searching.	the human prion gene contains five copies of a 24 nt repeat that is highly conserved among species. an analysis of folding free energies of the human prion mrna, in particular in the repeat region, suggested biased codon selection and the presence of rna patterns. in particular, pseudoknots, similar to the one predicted by wills in the human prion mrna, were identified in the repeat region of all available prion mrnas available in genbank, but not those of birds and the red slider turtle. an ali ...	2001	11160898
evolutionary adaptation to temperature. viii. effects of temperature on growth rate in natural isolates of escherichia coli and salmonella enterica from different thermal environments.	are enteric bacteria specifically adapted to the thermal environment of their hosts? in particular, do the optimal temperatures and thermal niches of the bacterial flora reflect seasonal, geographic, or phylogenetic differences in their hosts' temperatures? we examined these questions by measuring the relationship between the temperature-dependent growth rates of enteric bacteria in a free-living ectothermic host. we sampled two species of enteric bacteria (escherichia coli and salmonella enteri ...	2001	11263744
pituitary adenylate cyclase activating polypeptide is highly abundant in the nervous system of anoxia-tolerant turtle, pseudemys scripta elegans.	the levels of the pituitary adenylate cyclase activating polypeptide (pacap) were measured in the central nervous system and in peripheral organs of the anoxia-tolerant freshwater turtle, pseudemys scripta elegans by radioimmunoassay. the concentration of pacap38 was strikingly high in the central nervous system and lower but considerable immunoreactivity was detected in the peripheral organs. levels of pacap38 in the turtle brain exceed those measured in rat and human brain areas by 10-100-fold ...	2001	11390016
negative test for cloacal drinking in a semi-aquatic turtle (trachemys scripta), with comments on the functions of cloacal bursae.	many aquatic turtles possess paired evaginations of the cloaca called cloacal bursae. despite more than two centuries of study, little consensus exists as to the function(s) of these organs. we tested a recent suggestion that bursae could function in water uptake ("cloacal drinking"). turtles (trachemys scripta) were dehydrated (68-86% of maximum body mass) and given the opportunity to drink orally or cloacally. dehydration caused increases in hematocrit and osmolality of extracellular fluid (ec ...	2001	11479904
interactions of salmonella enterica serovar muenchen with macrophages of the turtle trachemys scripta scripta.	interactions of salmonella with macrophages have been studied in birds and, most extensively, in mammals. in these homeothermic animals, interactions between salmonella and macrophages are characterized by the following processes. after macropinocytosis, spacious phagosomes are formed within the macrophage. partial inhibition of phagosome-lysosome fusion and resistance to the formation of reactive oxygen species and reactive nitrogen intermediates enable the bacterium to survive and even multipl ...	2002	11755678
expression of kin, a nuclear protein binding to curved dna, in the brain of the frog (rana esculenta), turtle (trachemys scripta), quail (coturnix coturnix) and mouse (mus musculus).	the distribution of kin protein, the vertebrate homologue of the bacterial reca nuclear protein involved in illegitimate recombinant dna repair and gene regulation, was analysed in the brain of the mouse, quail, turtle and frog by immunocytochemical methods. the protein was expressed in all brains, but not in a uniform manner. immunoreactivity was absent from major fibre tracts. in the cerebral nuclei, immunolabelling in the various species showed an important variation. a comparative analysis, ...	2002	11875664
pathogenesis of infections with salmonella enterica subsp. enterica serovar muenchen in the turtle trachemys scripta scripta.	the pathogenesis of salmonella enterica subsp. enterica serovar muenchen infections in the aquatic turtle trachemys scripta scripta was studied. after oral infection with 5x10(5)cfu of serovar muenchen of 10-14-month-old turtles, kept at 26 degrees c, the intestine and especially the ileum, caecum and colon was colonized. invasion of the intestinal wall, causing histopathological lesions, and colonization of internal organs were not observed. serovar muenchen was only isolated from turtles for 8 ...	2002	12069769
cloning and expression of the turtle (trachemys scripta) immunoglobulin joining (j)-chain cdna.	the j-chain protein is a m(r) 15000 polypeptide associated with polymeric iga and igm. the complete cdna sequences of human, mouse, cow, brushtail possum, chicken and frog j chains have been previously reported, but nothing is known about the cdna and amino acid sequences of reptilian j chain. here, we determined a turtle j-chain cdna sequence by rt-pcr and race, and examined j-chain mrna and protein expression by northern blotting and immunohistochemistry. this turtle j-chain cdna was 1934 bp a ...	2002	12389099
pacap inhibits anoxia-induced changes in physiological responses in horizontal cells in the turtle retina.	pituitary adenylate cyclase activating polypeptide (pacap) has neurotrophic and neuroprotective effects against various cytotoxic agents in vitro, and ischemia in vivo. anoxia tolerance is most highly developed in some species of turtles. recently, we have demonstrated high levels of pacap38 in the turtle brain, exceeding those in corresponding rat and human brain areas by 10- to 100-fold. the aim of the present study was to investigate with electrophysiological methods the protective effects of ...	2002	12409217
histochemical distribution of acid mucopolysaccharides in the tongue of reptiles. i. chelonia (pseudemys scripta clark).		2002	128315
sperm storage in turtles: a male perspective.	the storage and behavior of sperm collected from the epididymis of two emyiid turtles were examined. in chrysemys picta, the weight of the epididymis does not change significantly throughout the year as does the testis. however, in this species, as well as in trachemys scripta, the epididymis contains sperm throughout the entire year. sperm from both species have a relatively low motility and velocity of movement. in c. picta, equally low motilities are observed both in the autumn, shortly after ...	2002	11754033
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
the intracardiac shunt as a source of myocardial oxygen in a turtle, trachemys scripta.	the functional significance of many features of the reptilian cardiopulmonary system remains unknown; particularly the importance of cardiac shunts. one hypothesis for a physiological function for shunts is that they play a role in myocardial oxygenation and are therefore important when cardiac work is elevated. in this study we examined cardiac function by monitoring electrocardiograms in red-eared slider turtles (trachemys scripta) with a reduced myocardial oxygen supply. exposing the animals ...	2002	21708712
high-speed vsd imaging of visually evoked cortical waves: decomposition into intra- and intercortical wave motions.	in the pond turtle, pseudemys scripta elegans, visually evoked cortical waves propagate at different velocities within the primary visual area compared with waves that pass into the secondary visual area. in an effort to separate intra- and intercortical wave motions, movies of visually evoked cortical waves recorded by high-speed voltage-sensitive dye (vsd) imaging were subjected to karhunen-loéve (kl) decomposition. this procedure decomposes the vsd movies into a series of basis images that ca ...	2002	11877522
hormone levels in yolk decline throughout development in the red-eared slider turtle (trachemys scripta elegans).	this study investigates the potential effects of maternally derived hormones present in the yolk of reptile eggs. specifically, we ask when are these hormones utilized by developing red-eared slider turtles (trachemys scripta elegans), a species with temperature-dependent sex determination (tsd). eggs were incubated at 27 degrees c, a male-producing temperature, and at 31 degrees c, a female-producing temperature. concentrations of progesterone, testosterone, and 17beta-estradiol were measured a ...	2002	12460601
turtle sex determination assay: mass balance and responses to 2,3,7,8-tetrachlorodibenzo-p-dioxin and 3,3',4,4',5-pentachlorobiphenyl.	polyhalogenated hydrocarbons have been implicated in the anomalous sexual differentiation of mammals and reptiles. here, a temperature-sensitive turtle sex determination assay using the red-eared slider (trachemys scripta elegans) was used to determine the estrogenic or antiestrogenic activity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (tcdd) and 3,3',4,4',5-pentachlorobiphenyl (pcb-126). neither tcdd nor pcb-126 showed a statistically significant difference in the resulting sex ratios (fisher's exa ...	2002	12389929
adrenergic control of the cardiovascular system in the turtle trachemys scripta.	freshwater turtles, trachemys scripta, like all non-crocodilian reptiles, are able to shunt blood between the pulmonary and systemic circulations owing to their undivided ventricle. the prevailing hypothesis is that the ratio of pulmonary and systemic resistances is the primary determinant of cardiac shunting in turtles. in the present study, we have examined the adrenergic influences on vascular resistances in the pulmonary and systemic circulations and the associated effects on cardiac shunts ...	2002	12324543
dacryops in a red-eared slider (chrysemys scripta elegans): case report.	clinical and histologic findings of an orbital lacrimal cyst (dacryops) in a 23-year-old-female red-eared slider (chrysemys scripta elegans) are described. main ophthalmologic findings included unilateral exophthalmus, engorged episcleral vessels, periocular swelling superior to the globe, incomplete lid closure, and reduced ocular motility. based on sonographic and cytologic examination of the tissue, the preliminary diagnosis of an orbital cyst was established. after surgical resection of the ...	2002	12236878
experimental manipulation of steroid concentrations in circulation and in egg yolks of turtles.	steroid hormones in egg yolks are increasingly recognized as an important component of maternal and offspring fitness in oviparous vertebrates. yet, except for in birds, the mechanism by which females allocate these resources is poorly understood. we manipulated systemic levels of hormones in reproductively mature female red-eared slider turtles (trachemys scripta elegans) with silastic implants to test the hypothesis that hormones are allocated to developing follicles as a quantitative function ...	2002	12115919
mechanisms for maintaining extracellular glutamate levels in the anoxic turtle striatum.	the turtle trachemys scripta is one of a limited group of vertebrates that can withstand hours to days without oxygen. one facet of anoxic survival is the turtle's ability to maintain basal extracellular glutamate levels, whereas in most vertebrates, anoxia triggers massive excitotoxic glutamate release. we investigated glutamate release and reuptake in the anoxic turtle and the effects of adenosine and atp-sensitive potassium (k(atp)) channels on glutamate homeostasis. striatal extracellular gl ...	2002	11959671
gene transcription of brain voltage-gated potassium channels is reversibly regulated by oxygen supply.	voltage-dependent potassium channels (kv channels) are important determinants of brain electrical activity. hypoxia may be an important modifier, because several voltage-gated k+ channels are reversibly blocked by acute hypoxia and are thought to act as oxygen sensors. here we show, using the anoxia-tolerant turtle brain (trachemys scripta) as a model, that brain kv1 channel transcription is reversibly regulated by oxygen supply. we found that in turtle brains exposed to 4-h anoxia kv1 transcrip ...	2003	14615400
effects of fatigue on the catchlike property in a turtle hindlimb muscle.	the purpose of this report was to test for the possibility that a catchlike, force-enhancing property, attributable to a particular stimulation pattern, could be evoked in non-mammalian turtle muscle, just as it has been shown in mammalian muscle. we tested for the presence of this property in dynamic lengthening and shortening contractions, as well as in the more commonly studied isometric contractions. a second aim was to note the effects of fatigue on the catchlike property, if the latter was ...	2003	14566421
connectivity of the turtle accessory optic system.	recent whole-cell recordings show that there are multiple synaptic inputs to the accessory optic system of the pond turtle pseudemys scripta elegans (the basal optic nucleus, bon), suggesting a complex role in visual processing. the bon outputs have now been investigated using transport of dii, rhodamine-conjugated and biotinylated dextrans. although transport was primarily anterograde, contralateral retinal ganglion cells were labeled retrogradely, confirming that the injection site was a retin ...	2003	14519514
colocalization of wt1 and cell proliferation reveals conserved mechanisms in temperature-dependent sex determination.	during vertebrate development the gonad has two possible fates, the testis or the ovary. the choice between these fates is made by a variety of sex-determining mechanisms, from the sex-determining gene on the y chromosome (sry) in mammals, to nongenetic temperature-dependent systems in many reptiles. despite the differences in the mechanisms at the top of the sex-determining cascade, the resulting morphology and many genes involved in early testis and ovarian development are common to most verte ...	2003	12717730
malignant ovarian teratoma in a red-eared slider (trachemys scripta elegans).	a 7-year-old intact female red-eared slider (trachemys scripta elegans) presented with anorexia of 2-3-weeks duration. coelomic radiographs demonstrated 3 shelled eggs in the right cavity. hormone therapy failed to induce oviposition. exploratory laparotomy revealed 3 calcified eggs in the right oviduct and a large mass obliterating the left ovary. the large, multilobulate mass had scattered, firm, white nodules and weighed 450 g. histopathology revealed a malignant teratoma composed of immature ...	2003	12580303
cloning and expression of aromatase in a turtle with temperature-dependent sex determination.	it has been hypothesized that estrogen production may play a pivotal role in the sex determination of reptiles with temperature-dependent sex determination (tsd). this hypothesis has been furthered by studies that have shown higher aromatase activity in the developing ovaries in some reptiles. however, other studies have not consistently supported this hypothesis. in the current study we addressed this issue by cloning p450 aromatase cdna in the turtle, trachemys scripta, and developing a quanti ...	2003	12568787
cytological evaluation of spermatogenesis and organization of the germinal epithelium in the male slider turtle, trachemys scripta.	the germ cell development in the slider turtle (trachemys scripta) testis was investigated by viewing the histology of the seminiferous epithelium in plastic sections with a light microscope. germ cell morphologies in the slider turtle testis were similar to the morphologies of other vertebrate germ cell types. however, the slider turtle seminiferous epithelium contained germ cells that progress through spermatogenesis in a temporal rather than a spatial pattern, resulting in a single spermatoge ...	2003	12520551
structure and growth of the utricular macula in the inner ear of the slider turtle trachemys scripta.	in general, postembryonic production of inner ear vestibular hair cells (hcs) is believed to occur in all nonmammalian vertebrates. however, no study on this topic has been published on reptiles and, consequently, it is not known whether this also applies to these vertebrates. therefore, the present study applied stereological methods in order to estimate the total number of hcs in turtles of varying sizes. the findings are that in prehatchlings the utricular macula (um) contains approximately 4 ...	2003	14716509
expression of dmrt1 in a turtle with temperature-dependent sex determination.	there is a variety of sex determining mechanisms among vertebrates. many reptiles possess temperature-dependent sex determination (tsd), in which the incubation temperature of the egg determines the sex of the hatchling. the red-eared slider turtle, trachemys scripta has often been used as a model system for examining the physiology of tsd. in the current study, the expression of dmrt1 was examined during tsd in this turtle. dmrt1 is a putative regulator of sex determination/differentiation and ...	2003	14684999
morphological changes induced by prolonged darkness in the retinal pigment epithelium of the turtle (pseudemys scripta elegans).	the retinal pigment epithelium of vertebrates was shown to be sensitive to cyclic oscillations of light and darkness. the morphological changes induced by prolonged darkness on the retinal epithelial cells of the freshwater turtle were studied, with particular regard to their localization and to their reversibility if animals are recovered under cyclic light. the eyes were processed for light and electron microscopy and a morphological and morphometric analysis was performed on the specimens. af ...	2003	10575821
environmental biodosimetry: a biologically relevant tool for ecological risk assessment and biomonitoring.	biodosimetry, the estimation of received doses by determining the frequency of radiation-induced chromosome aberrations, is widely applied in humans acutely exposed as a result of accidents or for clinical purposes, but biodosimetric techniques have not been utilized in organisms chronically exposed to radionuclides in contaminated environments. the application of biodosimetry to environmental exposure scenarios could greatly improve the accuracy, and reduce the uncertainties, of ecological risk ...	2003	12590073
immunohistochemical localization of darpp-32 in the brain of the turtle, pseudemys scripta elegans: further assessment of its relationship with dopaminergic systems in reptiles.	a previous study in the lizard gekko gecko has revealed that the distribution of darpp-32 (a phosphoprotein related to the dopamine d(1)-receptor) largely resembles the pattern observed in birds and mammals, at least as far as basal ganglia structures are concerned. on the other hand, several specific features of darpp-32 distribution in the gekkonid brain were noted that deserved further attention, e.g. cellular co-localization of darpp-32 and tyrosine hydroxylase (th) immunoreactivity in hypot ...	2003	12663057
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
interactions of salmonella enterica subsp. enterica serovar muenchen with intestinal explants of the turtle trachemys scripta scripta.	salmonella infections in reptiles, in contrast to those in birds and mammals, are limited to the intestinal tract. in this study, interactions of a strain of salmonella enterica subsp. enterica serovar muenchen (seem) with intestinal explants of the turtle trachemys scripta scripta were examined by scanning electron microscopy (sem). adhesion and invasion in the chelonian intestinal explants at 30 degrees c and 37 degrees c were evaluated quantitatively. for purposes of comparison, the invasive ...	2003	12634088
etiology of ovarian failure in blepharophimosis ptosis epicanthus inversus syndrome: foxl2 is a conserved, early-acting gene in vertebrate ovarian development.	blepharophimosis ptosis epicanthus inversus syndrome (bpes) is a human disorder caused by mutations in the forkhead transcription factor gene foxl2 and is characterized by facial dysmorphology combined in some cases with ovarian failure. to better understand the role of foxl2 in the etiology of ovarian failure in bpes, we examined its expression in embryonic ovaries of mice, chickens, and red-eared slider turtles, representatives of three phylogenetically distant vertebrate groups that have diff ...	2003	12810580
characterization of lipoproteins from the turtle, trachemys scripta elegans, in fasted and fed states.	the lipid and apolipoprotein composition of vldl, idl, ldl, hdl(2) and hdl(3) were examined in the turtle, trachemys scripta elegans, in fasted and fed states. the lipid composition of turtle lipoproteins was very similar to their human counterparts. the major apolipoprotein found in ldl, idl and vldl, which has a molecular weight of approximately 550 kd, is a homologue of apob100. the major apolipoprotein found in both hdl(2) and hdl(3), has a molecular weight of 28-kd and is homologous to huma ...	2003	12814787
origin and possible roles of the sox8 transcription factor gene during sexual development.	sox8 is a member of the sox family of developmental transcription factor genes and is closely related to sox9, a critical gene involved in mammalian sex determination and differentiation. both genes encode proteins with the ability to bind similar dna target sequences, and to activate transcription in in vitro assays. expression studies indicate that the two genes have largely overlapping patterns of activity during mammalian embryonic development. a knockout of sox8 in mice has no obvious devel ...	2003	14684985
origin and possible roles of the sox8 transcription factor gene during sexual development.	sox8 is a member of the sox family of developmental transcription factor genes and is closely related to sox9, a critical gene involved in mammalian sex determination and differentiation. both genes encode proteins with the ability to bind similar dna target sequences, and to activate transcription in in vitro assays. expression studies indicate that the two genes have largely overlapping patterns of activity during mammalian embryonic development. a knockout of sox8 in mice has no obvious devel ...	2003	14689607
sox8 is expressed at similar levels in gonads of both sexes during the sex determining period in turtles.	a critical gene involved in mammalian sex determination and differentiation is the sry-related gene sox9. in reptiles, sox9 resembles that of mammals in both structure and expression pattern in the developing gonad, but a causal role in male sex determination has not been established. a closely related gene, sox8, is conserved in human, mouse, and trout and is expressed in developing testes and not developing ovaries in mouse. in this study, we tested the possibility of sox8 being important for ...	2004	15366016
cellular mechanisms of sex determination in the red-eared slider turtle, trachemys scripta.	in all vertebrates sex determination is the step at which development of a testis or ovary is initiated in the bipotential gonad. although mus musculus and the red-eared slider turtle, trachemys scripta, use different mechanisms to initiate organogenesis of the testis (the y-linked gene, sry, in the mouse vs. the incubation temperature of the egg in the turtle), the structure of the adult testis is strikingly similar. we have identified several cellular mechanisms involved in testis organogenesi ...	2004	15454268
absence of detectable salmonella cloacal shedding in free-living reptiles on admission to the wildlife center of virginia.	salmonellosis is an important reptile-associated zoonotic infection in the united states. cloacal swabs were collected from reptiles admitted to the wildlife center of virginia, waynesboro, virginia, cultured for salmonella using hektoen and xylose lysine deoxycholate agars, and inoculated in selenite broth. all three were incubated at 37 degrees c for 18-24 hr. seventy-five animals were included in the study, representing eight species, 34 eastern box turtles (terrapene carolina carolina), 14 e ...	2004	15732603
comparative analyses of serum vitellogenin levels in male and female reeves' pond turtles (chinemys reevesii) by an immunological assay.	a quantitative immunological method was developed for measuring serum vitellogenin levels of reeves' pond turtles (chinemys reevesii) to investigate the effects of endocrine disruptors on the freshwater ecosystem. vitellogenin was induced by injecting estradiol-17beta into c. reevesii turtles (adult females, juvenile females, and males) and was purified from the turtle serum by edta-mgcl2 precipitation followed by gel filtration. using a polyclonal antibody raised against c. reevesii vitellogeni ...	2004	14513265
normal echoanatomy of the red-eared slider terrapin (trachemys scripta elegans).	thirty red-eared slider terrapins (trachemys scripta elegans) were examined by ultrasound to establish the normal ultrasonographic appearance of their coelomic structures. they were not sedated, and owing to their small size they were examined through the inguinal window of the carapace. high resolution transducers (7.5 and 11 mhz) enhanced the ultrasonographic imaging of the bowel, urinary bladder, liver, gall bladder, heart, kidney and gonads, but the pancreas, adrenal glands, thyroid glands a ...	2004	15508841
the cardiovascular responses of the freshwater turtle trachemys scripta to warming and cooling.	seven freshwater turtles trachemys scripta were instrumented with flow probes and cannulated for blood pressure measurements. the turtles were warmed from 24 to 34 degrees c, and cooled down to 24 degrees c, with and without atropine. animals exhibited a hysteresis of heart rate and blood flow to both the pulmonary and systemic circulations, which was not cholinergically mediated. blood pressure remained constant during both warming and cooling, while systemic resistance decreased during heating ...	2004	15037641
resistance to disuse atrophy in a turtle hindlimb muscle.	the purpose of this study was to characterize the changes in a turtle hindlimb muscle (external gastrocnemius) after exposure to three conditions of disuse: immobilization, tenotomy, and spinalization. histochemical analysis and measurement of muscle fiber cross-sectional area and weighted cross-sectional area were used to assess the potential conversion of muscle fiber types and changes in fiber size. it was found that unlike its counterpart in mammalian endotherms, the external gastrocnemius m ...	2004	14968256
structural determination and histochemical localization of ghrelin in the red-eared slider turtle, trachemys scripta elegans.	we purified ghrelin peptide and determined the cdna sequence encoding the precursor protein from the stomach of the red-eared slider turtle, trachemys scripta elegans. the trachemys ghrelin is comprised of 25-amino acids and has the sequence gssflspeyqntqqrkdpkkhtkln. the third serine residue was modified by n-octanoic (c8:0), decanoic (c10:0) or unsaturated decanoic acid (c10:1). the carboxyl-terminal end of the peptide was not amidated, as seen in the ghrelins of other land vertebrates. quanti ...	2004	15242751
differences between stereocilia numbers on type i and type ii vestibular hair cells.	a major outstanding goal of vestibular neuroscience is to understand the distinctive functional roles of type i and type ii hair cells. one important question is whether these two hair cell types differ in bundle structure. to address this, we have developed methods to characterize stereocilia numbers on identified type i and type ii hair cells in the utricle of a turtle, trachemys scripta. our data indicate that type i hair cells, which occur only in the striola, average 95.9 +/-16.73 (sd) ster ...	2004	15201311
endocrine-disrupting compounds and mixtures: unexpected dose-response.	the current study examined the effects on the red-eared slider turtle of extremely low doses of three endocrine-disrupting compounds (edcs)--trans-nonachlor, chlordane, and p,p'-dde-singly and in mixtures. previous studies using the red-eared slider turtle have proven its value as an organism for obtaining information about the effects of endocrine-disrupting compounds. the sex of the turtle, easily manipulated by exposure during embryogenesis, continues to be a marker of effects. when red-eared ...	2004	15106679
[reproductive ecology and hunting of the turtle tachemys scropta (testudinata: emydidae) in the "momposine depression", northern colombia].	we studied the reproductive ecology of the slider turtle. trachemys scripta callirostris, during the reproductive season of the year 2000, in an area of the mompós depression, northern colombia. we examined the number of nests ovoposited in locations with different characteristics, their hatching success rates and the natural causes of egg mortality. we also determined the effects of exploitation of nesting females, in two populations with different levels of harvesting. the results showed that ...	2004	17357421
alpha-adrenergic regulation of systemic peripheral resistance and blood flow distribution in the turtle trachemys scripta during anoxic submergence at 5 degrees c and 21 degrees c.	anoxic exposure in the anoxia-tolerant freshwater turtle is attended by substantial decreases in heart rate and blood flows, but systemic blood pressure (p(sys)) only decreases marginally due to an increase in systemic peripheral resistance (r(sys)). here, we investigate the role of the alpha-adrenergic system in modulating r(sys) during anoxia at 5 degrees c and 21 degrees c in the turtle trachemys scripta, and also describe how anoxia affects relative systemic blood flow distribution (%.q(sys) ...	2004	14668311
endothelin-1 causes systemic vasodilatation in anaesthetised turtles (trachemys scripta) through activation of etb-receptors.	the effects of endothelin-1 (et-1) on systemic and pulmonary circulation were investigated in anaesthetised freshwater turtles (trachemys scripta) instrumented with arterial catheters and blood flow probes. bolus intra-arterial injections of et-1 (0.4-400 pmol kg(-1)) caused a dose-dependent systemic vasodilatation that was associated with a decrease in systemic pressure (p(sys)) and a rise in systemic blood flow (q(sys)), causing systemic conductance (g(sys)) to increase. et-1 had no significan ...	2005	16169951
endocrine and behavioral response to a decline in habitat quality: effects of pond drying on the slider turtle, trachemys scripta.	the effect of the simulated drying of a pond on the behavior and corticosterone secretion of trachemys scripta was measured in a field situation. slider turtles were held in experimental and control ponds (12 x 15 m) enclosed with a drift fence integrated with spring-triggered livetraps. the experimental pond water level was dropped 10 cm per day for 8 d, until water was completely drained. slider turtles responded to the draining of the pond by the emigration of the majority (75%) of the experi ...	2005	16161015
spinal cord injury-induced changes in breathing are not due to supraspinal plasticity in turtles (pseudemys scripta).	after occurrence of spinal cord injury, it is not known whether the respiratory rhythm generator undergoes plasticity to compensate for respiratory insufficiency. to test this hypothesis, respiratory variables were measured in adult semiaquatic turtles using a pneumotachograph attached to a breathing chamber on a water-filled tank. turtles breathed room air (2 h) before being challenged with two consecutive 2-h bouts of hypercapnia (2 and 6% co2 or 4 and 8% co2). turtles were spinalized at dorsa ...	2005	16099823
purification and properties of the glutathione s-transferases from the anoxia-tolerant turtle, trachemys scripta elegans.	glutathione s-transferases (gsts) play critical roles in detoxification, response to oxidative stress, regeneration of s-thiolated proteins, and catalysis of reactions in nondetoxification metabolic pathways. liver gsts were purified from the anoxia-tolerant turtle, trachemys scripta elegans. purification separated a homodimeric (subunit relative molecular mass =34 kda) and a heterodimeric (subunit relative molecular mass = 32.6 and 36.8 kda) form of gst. the enzymes were purified 23-69-fold and ...	2005	16008560
androgen receptor in the oviduct of the turtle, trachemys scripta.	circulating androgens reach high concentrations in females of some reptiles and amphibians. we are testing the hypothesis that androgens can act directly in female reptilian reproductive tissues, via the androgen receptor. in this study, we sought to determine if androgen receptors are present in the oviduct of the turtle, trachemys scripta, using radioligand-binding assays and immunological assays. an androgen-binding site was detected in turtle oviductal cytosol and oviductal nuclear extract b ...	2005	15820135
thalamocortical connections in the pond turtle pseudemys scripta elegans.	thalamocortical connections are a neuroanatomical feature shared among vertebrates, although the extent and organization of these connections vary among species. from an evolutionary standpoint, reptiles represent early stages of the pattern of connectivity between the thalamus and cortex, and elucidation of these pathways may help to reveal the biological significance of these projections. the present tract tracing study was performed to examine the organization of thalamocortical projections i ...	2005	15761219
adenosine and atp-sensitive potassium channels modulate dopamine release in the anoxic turtle (trachemys scripta) striatum.	excessive dopamine (da) is known to cause hypoxic/ischemic damage to mammalian brain. the freshwater turtle trachemys scripta, however, maintains basal striatal da levels in anoxia. we investigated da balance during early anoxia when energy status in the turtle brain is compromised. the roles of atp-sensitive potassium (k(atp)) channels and adenosine (ad) receptors were investigated as these factors affect da balance in mammalian neurons. striatal extracellular da was determined by microdialysis ...	2005	15718391
distribution of facial motor neurons in the pond turtle pseudemys scripta elegans.	a tract tracing study was performed to examine the localization of the facial nucleus in the brain stem of the pond turtle, pseudemys scripta elegans. neurobiotin and the fluorescent tracers alexa fluor 488 and 594 were used to retrogradely label neurons of the abducens or facial nerves. the results showed that the facial nucleus has two subnuclei, a medial group and a lateral group. measurements of cell size revealed no significant differences between these populations. double labeling studies ...	2005	15567568
neuronal control of turtle hindlimb motor rhythms.	the turtle, trachemys scripta elegans, uses its hindlimb during the rhythmic motor behaviors of walking, swimming, and scratching. for some tasks, one or more motor strategies or forms may be produced, e.g., forward swimming or backpaddling. this review discusses experiments that reveal characteristics of the spinal neuronal networks producing these motor behaviors. limb-movement studies show shared properties such as rhythmic alternation between hip flexion and hip extension, as well as variabl ...	2005	15452660
production of monoclonal antibodies against chinemys reevesii turtle vitellogenin and their usage for comparison of biochemical and immunological characters of vitellogenins and yolk proteins of freshwater turtles.	four hybridoma clones (acv-1, -3, -4, and -5) were established for chinemys reevesii (reeves' turtle) vitellogenin (vtg) as a precursor protein of egg yolk and a biomarker of environmental pollution. binding-inhibition experiments indicated that the epitopes of four mabs were distinct. no binding of acv-4 to c. reevesii vtg in the western blot suggests that the epitope of acv-4 would be dependent on the three-dimensional structure. acv-1, -3, and -5 bound to c. reevesii vtg in the western blot. ...	2005	16122960
temperature, genes, and sex: a comparative view of sex determination in trachemys scripta and mus musculus.	sex determination, the step at which differentiation of males and females is initiated in the embryo, is of central importance to the propagation of species. there is a remarkable diversity of mechanisms by which sex determination is accomplished. in general these mechanisms fall into two categories: genetic sex determination (gsd), which depends on genetic differences between the sexes, and environmental sex determination (esd), which depends on extrinsic cues. in this review we will consider t ...	2005	16046442
high density of neuropeptide y-innervation in the myenteric plexus of the turtle midgut. an immunocytochemical study.	using an indirect immunocytochemical method, a high density of npy-containing neural network is revealed in the myenteric plexus of the midgut of the turtle, pseudemys scripta elegans. the labelled elements included strongly stained small nerve cells and generally weakly labelled large ones of the plexus, as well as a substantial proportion of the nerve fibres within both the myenteric plexus and around blood vessels. pericellular baskets around nonstained nerve cells and in some cases around we ...	2005	2131706
prion protein nmr structures of chickens, turtles, and frogs.	the nmr structures of the recombinant prion proteins from chicken (gallus gallus; chprp), the red-eared slider turtle (trachemys scripta; tprp), and the african clawed frog (xenopus laevis; xlprp) are presented. the amino acid sequences of these prion proteins show approximately 30% identity with mammalian prion proteins. all three species form the same molecular architecture as mammalian prpc, with a long, flexibly disordered tail attached to the n-terminal end of a globular domain. the globula ...	2005	15647366
slow-tonic muscle fibers and their potential innervation in the turtle, pseudemys (trachemys) scripta elegans.	a description is provided of the ratio of slow-tonic vs. slow- and fast-twitch fibers for five muscles in the adult turtle, pseudemys (trachemys) scripta elegans. the cross-sectional area of each fiber type and an estimation of the relative (weighted) cross-sectional area occupied by the different fiber types are also provided. two hindlimb muscles (flexor digitorum longus, fdl; external gastrocnemius, eg) were selected on the basis of their suitability for future motor-unit studies. three neck ...	2005	15732049
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
properties of centre-hyperpolarizing, red-sensitive bipolar cells in the turtle retina.	1. responses of centre-hyperpolarizing, red-sensitive bipolar cells were studied by intracellular recording in the retina of the turtle, pseudemys scripta elegans. the identity of these cells was confirmed by procion yellow marking. 2. circles of light produced hyperpolarizing waves that were graded with intensity and could exceed -30mv in amplitude. the operating intensity range was similar to that of turtle cones. 3. flashes in the form of an annulus evoked graded depolarizations which could b ...	2005	1151785
eimeria pseudemydis lainson, 1968, from the red-eared turtle, pseudemys scripta elegans, in arkansas.		2005	1142563
design and control of the head retractor muscle in a turtle, pseudemys (trachemys) scripta: i. architecture and histochemistry of single muscle fibers.	we are using the head retractor muscle (rccq) of a turtle, pseudemys scripta, to analyze the neuromuscular mechanisms by which organisms vary the force and timing of muscle contraction. previously we demonstrated that rccq comprises three histochemically defined fiber types: fast glycolytic (fg), fast oxidative glycolytic (fog), and slow oxidative (so). in the present paper we report the 1) architectural features of single muscle fibers in rccq, including their lengths, diameters, and taper char ...	2006	1447408
adrenal-kidney and gonadal steroidogenesis during sexual differentiation of a reptile with temperature-dependent sex determination.	adrenal-kidney and gonadal steroidogenesis were studied during early development in the red-eared slider turtle, trachemys scripta, which exhibits temperature-dependent sex determination. in vitro steroid secretion by adrenal-kidney-gonad complexes (akgs) incubated for 6 hr was determined by radioimmunoassay (ria). akgs from presumptive males and females secreted progesterone at developmental stages before (stage 15), during (stages 17 and 19), and after (stage 21) the temperature-sensitive peri ...	2006	1426953
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
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
a severe salmonella enterica serotype paratyphi b infection in a child related to a pet turtle, trachemys scripta elegans.	our report highlights a case of severe childhood salmonellosis related to a pet turtle, a red-eared slider (trachemys scripta elegans). a 6-year-old girl had gastroenteritis complicated with sepsis caused by serotype paratyphi b, which shared the same pulsed-field gel electrophoresis profiles with the organism isolated from a pet turtle. based on our literature survey on childhood invasive salmonellosis acquired from reptiles, this case is the first documented reptile-associated salmonellosis in ...	2006	16632917
the role of the sarcoplasmic reticulum in the generation of high heart rates and blood pressures in reptiles.	the functional significance of the sarcoplasmic reticulum (sr) in the generation of high heart rates and blood pressures was investigated in four species of reptile; the turtle, trachemys scripta; the python, python regius, the tegu lizard, tupinanvis merianae, and the varanid lizard, varanus exanthematicus. force-frequency trials and imposed pauses were performed on ventricular and atrial tissue from each species with and without the sr inhibitor ryanodine, and in the absence and presence of ad ...	2006	16651560
oviductal sperm storage as a reproductive tactic of turtles.	the oviducts of two species of freshwater turtles were examined throughout the year to determine the distribution of sperm within the oviduct, the locations of stored sperm, and the onset of mating. sperm were stored in undifferentiated tubules and ducts of submucosal glands at the periphery of large glandular segments of the albumen and uterine regions of the oviduct. sperm transfer to females commenced in october in sternotherus odoratus and in january in trachemys scripta. the role of sperm s ...	2006	9803538
the bioconcentration factor of perfluorooctane sulfonate is significantly larger than that of perfluorooctanoate in wild turtles (trachemys scripta elegans and chinemys reevesii): an ai river ecological study in japan.	turtles rank high in the river food chain, and are suitable for predicting the bioconcentrations of chemicals through the food chain. trachemys scripta elegans (n=46) and chinemys reevesii (n=51) were captured in a river in japan, from september to october 2003 and april to june 2004. surface water samples were collected simultaneously from the same sites at which the turtles were caught. serum perfluorooctane sulfonate (pfos) ranged from 2.4 to 486 microg/l, while water pfos levels ranged from ...	2006	16040121
vitellogenin detection in caiman latirostris (crocodylia: alligatoridae): a tool to assess environmental estrogen exposure in wildlife.	environmental pollution with endocrine disrupting compounds (edcs) has adverse effects on the ecosystem's health. caiman latirostris are widely distributed in south american aquatic ecosystems. caimans have physiological and ecological characteristics that make them particularly vulnerable to edcs exposure and suitable candidate as a sentinel species. vitellogenin (vtg) is a yolk pre-cursor protein synthesized by the liver of non-mammalian vertebrates and induced in response to estrogen. purifie ...	2006	16292562
dmrt1 expression in response to estrogen treatment in a reptile with temperature-dependent sex determination.	dmrt1 has been implicated as an important factor in sex determination in all classes of vertebrates, including reptiles with temperature-dependent sex determination (tsd). specifically, early embryonic expression of dmrt1 appears to be an integral part of normal testicular development in vertebrates. recently, a number of tsd studies have placed dmrt1 expression at the top of a short list of putative temperature-sensitive events for tsd. dmrt1 expression has been shown to be up-regulated at male ...	2006	16217798
metal accumulation in eggs of the red-eared slider (trachemys scripta elegans) in the lower illinois river.	the illinois river is a highly utilized navigable waterway in the us midwest, and has historically been contaminated with metal toxicants from various industrial and municipal pollution sources. little information on metal contamination is available in the lower illinois river, and in particular, in the habitat of the red-eared slider (trachemys scripta elegans) at the southern end of the river near grafton, il. this study was conducted to determine current levels of metal contamination in water ...	2006	16216308
hair bundle heights in the utricle: differences between macular locations and hair cell types.	hair bundle structure is a major determinant of bundle mechanics and thus of a hair cell's ability to encode sound and head movement stimuli. little quantitative information about bundle structure is available for vestibular organs. here we characterize hair bundle heights in the utricle of a turtle, trachemys scripta. we visualized bundles from the side using confocal images of utricular slices. we measured kinocilia and stereocilia heights and array length (distance from tall to short end of b ...	2006	16177175
quantitative genetics of plastron shape in slider turtles (trachemys scripta).	shape variation is widespread in nature and embodies both a response to and a source for evolution and natural selection. to detect patterns of shape evolution, one must assess the quantitative genetic underpinnings of shape variation as well as the selective environment that the organisms have experienced. here we used geometric morphometrics to assess variation in plastron shell shape in 1314 neonatal slider turtles (trachemys scripta) from 162 clutches of laboratory-incubated eggs from two ne ...	2006	16637501
gene transcription of neuroglobin is upregulated by hypoxia and anoxia in the brain of the anoxia-tolerant turtle trachemys scripta.	neuroglobin is a heme protein expressed in the vertebrate brain in mammals, fishes, and birds. the physiological role of neuroglobin is not completely understood but possibilities include serving as an intracellular oxygen-carrier or oxygen-sensor, as a terminal oxidase to regenerate nad(+) under anaerobic conditions, or involvement in no or ros metabolism. as the vertebrate nervous system is particularly sensitive to hypoxia, an intracellular protein that helps sustain cellular respiration woul ...	2006	16636779