Publications

force development at elevated [mg2+]o and [k+]o in myocardium from the freshwater turtle (trachemys scripta) and influence of factors associated with hibernation.	the effects of high [mg(2+)](o) on force development were examined for heart muscle of freshwater turtle. plasma [mg(2+)] during hibernation may increase drastically and like plasma [k(+)] approach values as high as 10 mm. each experiment performed at either 20 or 5 degrees c involved four ventricular preparations of which one pair was exposed to 10, and one to 1 mmmg(2+). one preparation of each pair was furthermore exposed to 10 mm k(+), whereas the other was maintained at 2.5 mm k(+). during ...	2006	16928457
benign ovarian teratoma in a red-eared slider turtle (trachemys scripta elegans).		2006	16861392
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
nonadditive interactions between animal and plant diet items in an omnivorous freshwater turtle trachemys scripta.	nonadditive interactions occur when diet items interact with one another such that the net energy or nutrient gain from a mixed diet differs from that predicted by summing the gains from individual diet components. we quantified nonadditive effects between duckweed, lemma valdiviana, and grass shrimp, palaemontes paludosus, in the freshwater turtle trachemys scripta. we fed turtles 100% duckweed, 100% shrimp, and two mixed diets containing 67% duckweed, 33% shrimp and 14% duckweed, 86% shrimp (d ...	2006	16503179
ontogenetic diet shifts and digestive constraints in the omnivorous freshwater turtle trachemys scripta.	many reptiles undergo an ontogenetic diet shift from carnivory to herbivory. in this study, we used the yellow-bellied slider turtle, trachemys scripta, as a model to evaluate whether juvenile turtles are carnivorous because physiological constraints preclude herbivory. we conducted feeding trials in which we fed juvenile and adult turtles a duckweed plant, lemna valdiviana, or a freshwater grass shrimp, palaemontes paludosus, for 5 wk. during the trials, we measured mass-specific intake, digest ...	2006	16380936
toxicity of glyphosate as glypro and li700 to red-eared slider (trachemys scripta elegans) embryos and early hatchlings.	more than 8.2 billion ha of cropland, gardens, and forests are treated with the herbicide glyphosate each year. whereas the toxicity of glyphosate and associated adjuvants has been measured in other vertebrates, few, if any, studies have looked at their effects in reptiles. in some instances, management of turtle habitat requires control of successional stages through application of herbicides. adults and juvenile turtles may be exposed directly, whereas embryos may contact the chemicals through ...	2006	17022419
estrogen response system in the reproductive tract of the male turtle: an immunocytochemical study.	portions of the reproductive tract of the male (trachemys scripta) turtle were examined by immunocytochemistry for evidence of the capacity to produce and respond to estrogen hormones (via the expression of p450 aromatase and estrogen receptors). aromatase was detected in both the sertoli and leydig cells of the testis and was expressed at different levels during the spermatogenic cycle, being highest in the quiescent testis and lowest during germ cell meiosis. eralpha was found in the leydig ce ...	2007	16935286
expression of sox9, mis, and dmrt1 in the gonad of a species with temperature-dependent sex determination.	sex determination in vertebrates, the process of forming an ovary or testis from a bipotential gonad, can be initiated by genetic or environmental factors. elements of the downstream molecular pathways underlying these different sex-determining mechanisms have been evolutionarily conserved. we find the first evidence that sox9 expression is preferentially organized in the testis early in the temperature-sensitive period in a species with temperature-dependent sex determination (trachemys scripta ...	2007	17326219
pharmacokinetics of metronidazole in the red-eared slider turtle (trachemys scripta elegans) after single intracoelomic injection.		2007	17348904
steroid signaling system responds differently to temperature and hormone manipulation in the red-eared slider turtle (trachemys scripta elegans), a reptile with temperature-dependent sex determination.	many reptiles, including the red-eared slider turtle (trachemys scripta elegans), exhibit temperature-dependent sex determination (tsd). temperature determines gonadal sex during the middle of embryogenesis, or the temperature-sensitive period (tsp), when gonadal sex is labile to both temperature and hormones--particularly estrogen. the biological actions of steroid hormones are mediated by their receptors as defined here as the classic transcriptional regulation of target genes. to elucidate es ...	2007	18391529
distribution and characteristics of endogenous digestive enzymes in the red-eared slider turtle, trachemys scripta elegans.	distribution and properties of the main digestive enzymes including protease and amylase, from stomach, pancreas and the anterior, middle and posterior intestine of the adult red-eared slider turtle trachemys scripta elegans were studied at various phs and temperatures. the optimum temperature and ph for protease in stomach, pancreas and the anterior, middle and posterior intestine were 40 degrees c, 2.5; 50 degrees c, 8.0; 50 degrees c, 7.0; 50 degrees c, 8.0; and 50 degrees c, 8.5; respectivel ...	2007	17462929
effect of temperature and prolonged anoxia exposure on electrophysiological properties of the turtle (trachemys scripta) heart.	cardiac activity of the turtle (trachemys scripta) is greatly depressed with cold acclimation and anoxia. we examined what electrophysiological modifications accompany and perhaps facilitate this depression of cardiac activity. turtles were first acclimated to 21 degrees c or 5 degrees c and held under either normoxic or anoxic (6 h at 21 degrees c; 14 days at 5 degrees c) conditions. we then measured cardiac action potentials (aps) using spontaneously contracting whole heart preparations and wh ...	2007	17442785
immunohistochemical and hodological characterization of calbindin-d28k-containing neurons in the spinal cord of the turtle, pseudemys scripta elegans.	neurons and fibers containing the calcium-binding protein calbindin-d28k (cb) were studied by immunohistochemical techniques in the spinal cord of adult and juvenile turtles, pseudemys scripta elegans. abundant cell bodies and fibers immunoreactive for cb were widely and distinctly distributed throughout the spinal cord. most neurons and fibers were labeled in the superficial dorsal horn, but numerous cells were also located in the intermediate gray and ventral horn. in the dorsal horn, most cb- ...	2007	17203484
lactate uptake by skeletal bone in anoxic turtles, trachemys scripta.	previous studies have shown that freshwater turtle shells can accumulate lactate during periods of anoxic submergence. our objective in this study was to determine lactate uptake in other parts of the turtle's skeleton. we measured lactate concentration of 7 skeletal elements and 4 shell samples of red-eared slider turtles, trachemys scripta, in control animals (n=12) and in animals following submergence for 4-5 days in n(2)-equilibrated water at 10 degrees c (n=8). we also collected blood sampl ...	2007	17188012
beyond anoxia: the physiology of metabolic downregulation and recovery in the anoxia-tolerant turtle.	the freshwater turtle trachemys scripta is among the most anoxia-tolerant of vertebrates, a true facultative anaerobe able to survive without oxygen for days at room temperature to weeks or months during winter hibernation. our good friend and colleague peter lutz devoted nearly 25 years to the study of the physiology of anoxia tolerance in these and other model organisms, promoting not just the basic science but also the idea that understanding the physiology and molecular mechanisms behind ano ...	2007	17049896
germ cell depletion does not alter the morphogenesis of the fetal testis or ovary in the red-eared slider turtle (trachemys scripta).	in the red-eared slider turtle, trachemys scripta, both prospective male and female gonads contain primitive cord structures at the time when the gonad first forms. primordial germ cells arrive in the gonad and accumulate on the coelomic surface. if testis development is initiated, these cords develop further at the same time that germ cells migrate from the coelomic surface and become sequestered in the interior of the cords. in contrast, in the developing ovary germ cells proliferate in a defi ...	2007	17041961
effects of extracellular changes on spontaneous heart rate of normoxia- and anoxia-acclimated turtles (trachemys scripta).	heart rate (f(h)) of the anoxia-tolerant freshwater turtle (trachemys scripta) during prolonged anoxia exposure is 2.5- to 5-times lower than the normoxic rate, but whether alterations in blood composition that accompany prolonged anoxia contribute to this bradycardia is unknown. we examined how temperature acclimation, oxygen deprivation, acidosis, hyperkalemia, hypercalcemia and adrenaline affect chronotropy in the turtle myocardium. we monitored spontaneous contraction rates of right-atrial p ...	2007	17234611
spatiotemporal structure of depolarization spread in cortical pyramidal cell populations evoked by diffuse retinal light flashes.	the spatiotemporal structure of cortical activity evoked by diffuse light flashes was investigated in an isolated eyecup-brain preparation of the pond turtle, pseudemys scripta. by combining a photomicroscopic image of the preparation with voltage-sensitive dye signals recorded by a 464-element photodiode array, the spread of depolarization within different cortical areas could be directly visualized with millisecond temporal resolution. diffuse stimulation of the contralateral eyecup initially ...	2007	10022479
differential n-acetylation of alpha-msh and beta-endorphin in the intermediate pituitary of the turtle, pseudemys scripta.	steady-state analyses of the intermediate pituitary of the turtle, pseudemys scripta, indicated that alpha-msh-sized immunoreactive forms and beta-endorphin-sized immunoreactive forms are major end products of melanotropic cells. three forms of alpha-msh-related immunoreactivity were detected. the two major forms had the same reversed-phase hplc properties as synthetic n,o-diacetyl-acth(1-13)-nh2 and n-acetyl-acth(1-13)-nh2. these forms accounted for 97% of the total alpha-msh-related immunoreac ...	2007	8234035
coelioscopic-assisted prefemoral oophorectomy in chelonians.	to describe a coelioscopic-assisted prefemoral oophorectomy technique for use in chelonians.	2007	17397348
shapes of differential pulse voltammograms and level of metallothionein at different animal species.	metallothioneins play a key role in maintaining homeostasis of essential metalsand in protecting of cells against metal toxicity as well as oxidative damaging. exceptinghumans, blood levels of metallothionein have not yet been reported from any animalspecies. blood plasma samples of 9 animal species were analysed by the adsorptive transferstripping technique to obtain species specific voltammograms. quite distinct records wereobtained from the takin (budorcas taxicolor), while other interesting ...	2007	28903235
effects of temperature on anoxic submergence: skeletal buffering, lactate distribution, and glycogen utilization in the turtle, trachemys scripta.	to test the hypothesis that submergence temperature affects the distribution of the lactate load and glycogen utilization during anoxia in turtles, we sampled a variety of tissues after 7 days, 24 h, and 4 h of anoxic submergence at 5, 15, and 25 degrees c, respectively. these anoxic durations were chosen because we found that they produced similar decreases in plasma hco(3)(-) ( approximately 18-22 meq/l). the sampled tissues included ventricle, liver, small intestine, carapace, and the followi ...	2007	17395788
flow cytometric analysis of red-eared slider turtles (trachemys scripta) from tar creek superfund site.	tar creek superfund site (tcsfs) was heavily mined from the 1890s to 1970 and currently is contaminated with lead, zinc, and cadmium. flow cytometry (fcm) was used to measure variation in nuclear dna content of red blood cells collected from trachemys scripta living within tcsfs and reference sites, lake carl blackwell (lcb) and sequoyah national wildlife refuge (snwr). we also used atomic absorption spectrometry to measure pb in blood and carapace and cd in blood samples of turtles from tcsfs a ...	2007	17364238
analgesic efficacy and respiratory effects of butorphanol and morphine in turtles.	to test the hypothesis that butorphanol or morphine induces antinociception with minimal respiratory depression in conscious red-eared slider turtles.	2007	17472564
layer thickness and curvature effects on otoconial membrane deformation in the utricle of the red-ear slider turtle: static and modal analysis.	finite element models of otoconial membrane (om) were developed to investigate the effects of three geometric variables on static and modal response of the om: (1) curvature of the macular surface, (2) spatial variation in thicknesses of three om layers, and (3) shape of the macular perimeter. a geometrically accurate model of a turtle utricle was constructed from confocal images. modifying values for each variable formed variants of this model: modeling the macula surface as flat, om layer thic ...	2007	18525141
regulation of extracellular glutamate levels in the long-term anoxic turtle striatum: coordinated activity of glutamate transporters, adenosine, k (atp) (+) channels and gaba.	early in anoxia the mammalian brain experiences an uncontrolled release of glutamate, which combined with the failure of glutamate reuptake mechanisms, leads to massive neurotoxic increases in extracellular glutamate. by contrast, the anoxia tolerant turtle (trachemys scripta) shows no increase in extracellular glutamate levels over many hours of anoxia. during the first hours of anoxia extracellular glutamate levels are maintained by a reduction in glutamate release (mainly due to the inhibitio ...	2007	17629717
adrenal-kidney-gonad complex measurements may not predict gonad-specific changes in gene expression patterns during temperature-dependent sex determination in the red-eared slider turtle (trachemys scripta elegans).	many turtles, including the red-eared slider turtle (trachemys scripta elegans) have temperature-dependent sex determination in which gonadal sex is determined by temperature during the middle third of incubation. the gonad develops as part of a heterogenous tissue complex that comprises the developing adrenal, kidney, and gonad (akg complex). owing to the difficulty in excising the gonad from the adjacent tissues, the akg complex is often used as tissue source in assays examining gene expressio ...	2007	17592622
gonadal expression of sf1 and aromatase during sex determination in the red-eared slider turtle (trachemys scripta), a reptile with temperature-dependent sex determination.	many egg-laying reptiles have temperature-dependent sex determination (tsd), where the offspring sex is determined by incubation temperature during a temperature-sensitive period (tsp) in the middle third of development. the underlying mechanism transducing a temperature cue into an ovary or testis is unknown, but it is known that steroid hormones play an important role. during the tsp, exogenous application of estrogen can override a temperature cue and produce females, while blocking the activ ...	2007	17490415
suppression of reactive oxygen species production enhances neuronal survival in vitro and in vivo in the anoxia-tolerant turtle trachemys scripta.	hypoxia-ischemia with reperfusion is known to cause reactive oxygen species-related damage in mammalian systems, yet, the anoxia tolerant freshwater turtle is able to survive repeated bouts of anoxia/reoxygenation without apparent damage. although the physiology of anoxia tolerance has been much studied, the adaptations that permit survival of reoxygenation stress have been largely ignored. in this study, we examine ros production in the turtle striatum and in primary neuronal cultures, and exam ...	2007	17326763
evaluation of a combination of sodium hypochlorite and polyhexamethylene biguanide as an egg wash for red-eared slider turtles (trachemys scripta elegans) to suppress or eliminate salmonella organisms on egg surfaces and in hatchlings.	to evaluate a combination of 2 nonantibiotic microbicide compounds, sodium hypochlorite (naocl) and polyhexamethylene biguanide (phmb), as a treatment to suppress or eliminate salmonella spp from red-eared slider (res) turtle (trachemys scripta elegans) eggs and hatchlings.	2007	17269881
analyzing the evolution of beta-endorphin post-translational processing events: studies on reptiles.	in many cartilaginous fishes, most ray-finned fishes, lungfishes, and amphibians, the post-translational processing of pomc includes the monobasic cleavage of beta-endorphin to yield an opioid that is eight to ten amino acids in length. the amino acid motif within the beta-endorphin sequence required for a monobasic cleavage event is -e-r-(s/g)-q-. mammals and birds lack this motif and as a result beta-endorphin(1-8) is a not an end-product in either group. since both mammals and birds were deri ...	2007	17353011
experimental transmission and induction of ranaviral disease in western ornate box turtles (terrapene ornata ornata) and red-eared sliders (trachemys scripta elegans).	an experimental transmission study was designed to determine whether a causal relationship exists between a ranavirus (bstrv) isolated from a burmese star tortoise that died and the lesions observed in that tortoise. a pilot study was performed with 3 box turtles (terrapene ornata ornata) and 3 red-eared sliders (ress; trachemys scripta elegans) to assess their suitability in a larger study. based on the outcome of this study, ress were selected, and 2 groups of 4 ress received either an oral (p ...	2007	17491069
characterization of a novel reptilian tolloid-like gene in the pond turtle, pseudemys scripta elegans.	the tolloid metalloproteases are pleiotropic enzymes that are important for many developmental processes. this study describes the isolation and characterization of a novel tolloid family member from the pond turtle pseudemys scripta elegans. the turtle tolloid, designated ttll, is found in two forms. the first, ttlls, contains a signal sequence which may provide a mechanism for secretion. the second, ttllc, does not contain a signal sequence and is likely cytoplasmic. sequence analysis of ttll ...	2007	17493594
purification and properties of glutathione reductase from liver of the anoxia-tolerant turtle, trachemys scripta elegans.	glutathione reductase (gr) is a homodimeric flavoprotein that catalyzes the reduction of oxidized glutathione (gssg) using nadph as a cofactor. the enzyme is a major component of cellular defense mechanisms against oxidative injury. in this study, gr was purified from the liver of the anoxia-tolerant turtle, trachemys scripta elegans. the overall fold purifications were 13.3- and 12.1-fold with final specific activities of 5.5 and 1.44 u/mg of protein for control and anoxic turtle gr, respective ...	2007	17075686
estuarine fish and turtles as intermediate and paratenic hosts of gnathostoma binucleatum in nayarit, mexico.	human gnathostomosis is a severe public health problem in the state of nayarit, mexico. between 1995 and 2005, the registration of human cases numbered 6,328, which makes it one of the largest focal points of the disease in the country. the present study determined the presence of natural hosts of gnathostoma binucleatum larvae at the laguna de agua brava in nayarit, mexico. a total of 5,450 fish and 247 turtles were sampled. muscular tissue was ground and observed against the light using a 100- ...	2007	17924145
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
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
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
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
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
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
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
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
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
monoclonal antibodies to the turtle cortex reveal neuronal subsets, antigenic cross-reactivity with the mammalian neocortex, and forebrain structures sharing a pallial derivation.	the dorsal cortex of the pond turtle (pseudemys scripta) is a relatively simple structure consisting of two principal classes of neurons that occupy three distinct layers. morphological, pharmacological, and physiological data suggest many similarities to the mammalian neocortex, rendering it an interesting preparation for comparative studies. we prepared monoclonal antibodies to the turtle dorsal cortex by immunizing mice with cortical tissue from adult turtles. twelve antibodies were generated ...	2008	2432104
turtle isochore structure is intermediate between amphibians and other amniotes.	vertebrate genomes are comprised of isochores that are relatively long (>100 kb) regions with a relatively homogenous (either gc-rich or at-rich) base composition and with rather sharp boundaries with neighboring isochores. mammals and living archosaurs (birds and crocodilians) have heterogeneous genomes that include very gc-rich isochores. in sharp contrast, the genomes of amphibians and fishes are more homogeneous and they have a lower overall gc content. because dna with higher gc content is ...	2008	21669806
the distal forelimb musculature in aquatic and terrestrial turtles: phylogeny or environmental constraints?	we compared the muscular anatomy of the distal front limb in terrestrial and aquatic chelonians to test whether observed differences between the two groups are associated with their divergent lifestyles and locomotor modes. given the different use of the forelimb in the two environments (body support and propulsion on land vs. mainly propulsion in water) we expected that: (1) aquatic and terrestrial turtles would show differences in their muscular anatomy, with aquatic species having more indivi ...	2008	19172731
carapace growth of the turtle chrysemys scripta: a longitudinal study of shape using fourier analysis.	because the majority of morphological structures encountered in biology are irregular in form, conventional metrics composed of distances, angles and ratios, are inefficient shape descriptors. to circumvent this drawback in the application of morphometrics to describe 2 dimensional shapes, an alternative procedure based on fourier analysis was developed and applied to the turtle carapace. once size differences were controlled for, the presence of shape changes with age could be demonstrated. thi ...	2008	2712325
coordinate action of pre- and postsynaptic brain-derived neurotrophic factor is required for ampar trafficking and acquisition of in vitro classical conditioning.	brain-derived neurotrophic factor (bdnf) has been implicated in mechanisms of synaptic plasticity such as long-term potentiation (ltp), but its role in associative learning remains largely unknown. in the present study, we investigated the function of bdnf and its receptor tropomyosin-related kinase b (trkb) in an in vitro model of classical conditioning using pond turtles, pseudemys scripta elegans. conditioning resulted in a significant increase in bdnf and phospho (p)-trk expression. bath app ...	2008	18639615
minimal volume regulation after shrinkage of red blood cells from five species of reptiles.	red blood cells (rbcs) from most vertebrates restore volume upon hypertonic shrinkage and the mechanisms underlying this regulatory volume increase (rvi) have been studied extensively in these cells. despite the phylogenetically interesting position of reptiles, very little is known about their red cell function. the present study demonstrates that oxygenated rbcs in all major groups of reptiles exhibit no or a very reduced rvi upon approximately 25% calculated hyperosmotic shrinkage. thus, rbcs ...	2008	18424207
formation and ossification of limb elements in trachemys scripta and a discussion of autopodial elements in turtles.	though sequences of formation and ossification of bony elements have been described for many taxa, controversy surrounds the formation of limb elements in turtles. three hypotheses for patterns of formation of autopodial elements have been proposed, differing primarily in the origin of distal carpal/tarsal 3, the digital arch, and centrale 4. patterns of formation and ossification of limb elements are described for trachemys scripta. these patterns are compared to similar data for representative ...	2008	18624573
estrogen inhibits caudal progression but stimulates proliferation of developing müllerian ducts in a turtle with temperature-dependent sex determination.	müllerian duct development appears to be similar in many vertebrate groups, and previous studies have shown that this development is estrogen sensitive. for example, embryonic exposure to diethylstilbestrol (des) in humans and mice, and estrogen exposure in chickens, can have multiple, usually adverse, effects on müllerian duct differentiation and growth. the current study investigates 17beta-estradiol's effects on müllerian duct development in a reptile, the turtle trachemys scripta. in t. scri ...	2008	18485773
cloning and expression of r-spondin1 in different vertebrates suggests a conserved role in ovarian development.	r-spondin1 (rspo1) is a novel regulator of the wnt/beta-catenin signalling pathway. loss-of-function mutations in human rspo1 cause testicular differentiation in 46, xx females, pointing to a role in ovarian development. here we report the cloning and comparative expression analysis of r-spondin1 orthologues in the mouse, chicken and red-eared slider turtle, three species with different sex-determining mechanisms. evidence is presented that this gene is an ancient component of the vertebrate ova ...	2008	18651984
inability to induce tympanic squamous metaplasia using organochlorine compounds in vitamin a-deficient red-eared sliders (trachemys scripta elegans).	previously, we reported that wild eastern box turtles (terrapene carolina carolina) with aural abscesses contained higher body burdens of organochlorine (oc) compounds than those without the lesion. this lesion in captive chelonians is associated with turtles that are fed diets deficient in vitamin a. to examine the pathophysiology of this lesion and evaluate the relationship between oc burdens and vitamin a metabolism, we maintained red-eared sliders (trachemys scripta elegans) under different ...	2008	18689652
molecular cloning and characterization of estrogen, androgen, and progesterone nuclear receptors from a freshwater turtle (pseudemys nelsoni).	steroid hormones are essential for the normal function of many organ systems in vertebrates. reproductive activity in females and males, such as the differentiation, growth, and maintenance of the reproductive system, requires signaling by the sex steroids. although extensively studied in mammals and a few fish, amphibians, and bird species, the molecular mechanisms of sex steroid hormone (estrogens, androgens, and progestins) action are poorly understood in reptiles. here we evaluate hormone re ...	2008	17916628
detection of salmonellae in different turtle species within a headwater spring ecosystem.	sediments and water from the slough arm of spring lake, the headwaters of the san marcos river, texas, usa, as well as swabs from biofilms on carapaces and from the cloacae of 18 common musk turtles (sternotherus odoratus), 21 red-eared sliders (trachemys scripta elegans), nine texas river cooters (pseudemys texana), one snapping turtle (chelydra serpentina serpentina), and three guadalupe spiny soft-shell turtles (apalone spinifera guadalupensis), caught at the same site, were analyzed for salm ...	2008	18436690
recoding of translation in turtle mitochondrial genomes: programmed frameshift mutations and evidence of a modified genetic code.	a +1 frameshift insertion has been documented in the mitochondrial gene nad3 in some birds and reptiles. by sequencing polyadenylated mrna of the chicken (gallus gallus), we have shown that the extra nucleotide is transcribed and is present in mature mrna. evidence from other animal mitochondrial genomes has led us to hypothesize that certain mitochondrial translation systems have the ability to tolerate frameshift insertions using programmed translational frameshifting. to investigate this, we ...	2008	19030769
a proposed role of the sulfotransferase/sulfatase pathway in modulating yolk steroid effects.	steroid hormones have long been studied by behavioral ecologists as a nongenetic means whereby females can influence the development of their offspring. in oviparous vertebrates, steroids are present in the yolk at the time of oviposition and have been shown to affect numerous traits of the offspring. to date, most studies have focused on the functional relationship between yolk steroids and offspring development. in this article we used a mechanistic approach to investigate the effects of yolk ...	2008	21669803
protein kinase c-dependent and independent signaling pathways regulate synaptic glur1 and glur4 ampar subunits during in vitro classical conditioning.	protein kinase c (pkc) signal transduction pathways have been implicated in mechanisms of synaptic plasticity and learning, however, the roles of the different pkc family isoforms remain to be clarified. previous studies showed that nmdar-mediated trafficking of glur4-containing ampars supports conditioning and that the mitogen-activated protein kinases (mapks) have a central role in the synaptic delivery of glur4 subunits. here, an in vitro model of classical conditioning in pond turtles, pseud ...	2008	18809472
inhibitory and excitatory effects of micro-, delta-, and kappa-opioid receptor activation on breathing in awake turtles, trachemys scripta.	for ectothermic vertebrates, such as reptiles, the effects of opioid receptor subtype activation on breathing are poorly understood. on the basis of previous studies on mammals and lampreys, we hypothesized that mu- and delta-opioid receptor (mor and dor, respectively) activation would cause respiratory depression, whereas kappa-opioid receptor (kor) activation would have no effect. to address this question, we measured respiration in awake, freely swimming adult red-eared slider turtles (trache ...	2008	18784338
histochemical and immunohistochemical characterization of exocrine cells in the foregut of the red-eared slider turtle, trachemys scripta (emydidae).	the morphofunctional organization of the exocrine cells in the foregut of the red-eared slider turtle, trachemys scripta, was investigated by histochemistry (pas, ab ph1.0 and ph 2.5, hid-ab, bowie), lectin-histochemistry (wga, sba, uea, cona, pna, dba, sialidase-sba, sialidase-pna, paradoxical cona), and immunohistochemistry (antipepsin, anti-alpha-h+,k+ atpase) to detect regional differences and verify the existence of an oro-aboral gradient in gastric juice secretion. observations showed that ...	2008	19556690
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
pharmacokinetics of buprenorphine after single-dose subcutaneous administration in red-eared sliders (trachemys scripta elegans).	buprenorphine, a mu opioid receptor agonist, is expected to be a suitable analgesic drug for use in reptiles. however, to date, dosage recommendations have been based on anecdotal observations. the aim of this study was to provide baseline pharmacokinetic data in red-eared sliders (trachemys scripta elegans) targeting a plasma level of 1 ng/ml reported effective for analgesia in humans. serial blood samples were taken after subcutaneous injection of buprenorphine, and plasma buprenorphine levels ...	2008	19110701
immunohistochemical localization of thyrotropin-releasing hormone in the brain of reptiles.	to gain insight into the evolution of the thyrotropin-releasing hormone (trh) system in the brain of vertebrates we have conducted a comparative analysis of the distribution of trh immunoreactive cell bodies and fibers in two reptiles, the turtle pseudemys scripta elegans and the lizard gekko gecko. double labeling for trh and tyrosine hydroxylase, the main catecholamine marker, was made to help the correct localization of the labeled structures and to evaluate the possible interaction of these ...	2008	18674611
immunohistochemical localization of neuropeptide ff-like in the brain of the turtle: relation to catecholaminergic structures.	a previous study in the lizard gekko gecko has revealed that neuropeptide ff (npff, a neuropeptide involved in nociception, cardiovascular regulation, and endocrine function) is widely distributed throughout the brain and spinal cord. although the distribution of npff immunoreactivity shares many features with that found in other vertebrates, it was noted that gekko shared more features with anamniotes in terms of number of cell groups, more elaborate networks of fibers, and lack of colocalizati ...	2008	18331881
fasting and postprandial serum bile acid concentrations in 10 healthy female red-eared terrapins (trachemys scripta elegans).	the fasting and postprandial serum concentrations of bile acids and other blood constituents were measured in a group of 10 clinically healthy, female, six-year-old captive red-eared terrapins (trachemys scripta elegans). the terrapins were housed in a temperate room and maintained in four aquaria in which the water temperature ranged from 24 to 27 degrees c and the temperature above the basking site ranged from 27 to 30 degrees c. the serum concentrations of bile acids were measured four times ...	2008	18953075
[the synaptic ribbons in the retina of the turtle (pseudemys scripta elegans): ultrastructural and chronobiological study].	the authors investigate the morphology and the behaviour of the synaptic ribbons (ns) in the outer plexiform layer of the retina of the turtle pseudemys scripta elegans during the 24 hrs cycle; the animals were subjected to a light-dark cycle = 12:12 hours. new ultrastructural features are demonstrated in the rod arciform density and in the fibers connecting the central axis of the ribbon with the presynaptic membrane (figs. 1 a-b). as to chronobiological data, the existence of different kinds o ...	2008	1781721
spectral properties of turtle cones.	microelectrodes were used to record from red and green cones of the turtle pseudemys scripta elegans. the purpose of this study was to determine the action spectra of the red and green cone photopigments, and to look closely for direct interactions between the two cone classes. an isolated retina preparation was employed so that cones could be stimulated from the outer segment side, thereby avoiding the oil droplets that reside in the inner segments of many cones and normally filter incident lig ...	2008	7786854
the pupillary response to light in the turtle.	when intense adapting lights are turned off, the pupil of the turtle, pseudemys scripta elegans, enlarges. the recovery functions for pupillary dilation have different time constants that are defined by red- and green-sensitive cones and rods as they are affected by prior light adaptation and time in the dark. pupillary area related to dilation responds over at least a three- to four-fold range. following white-light adaptation, the course of pupil dilation in the dark shows a three-legged curve ...	2008	8962831
teaching the toolkit: a laboratory series to demonstrate the evolutionary conservation of metazoan cell signaling pathways.	a major finding of comparative genomics and developmental genetics is that metazoans share certain conserved, embryonically deployed signaling pathways that instruct cells as to their ultimate fate. because the dna encoding these pathways predates the evolutionary split of most animal groups, it should in principle be possible to clone representatives of such signaling pathways from almost any species, demonstrating their sequence conservation. here i describe an 8-week laboratory series that te ...	2008	21591195
dendritic properties of turtle pyramidal neurons.	the six-layered mammalian neocortex evolved from the three-layered paleocortex, which is retained in present-day reptiles such as the turtle. thus the turtle offers an opportunity to examine which cellular and circuit properties are fundamental to cortical function. we characterized the dendritic properties of pyramidal neurons in different cortical regions of mature turtles, pseudemys scripta elegans, using whole cell recordings and calcium imaging from the axon, soma, and dendrites in a slice ...	2008	18045998
dependence of myosin-atpase on structure bound creatine kinase in cardiac myofibrils from rainbow trout and freshwater turtle.	the influence of myofibrillar creatine kinase on the myosin-atpase activity was examined in cardiac ventricular myofibrils isolated from rainbow trout (oncorhynchus mykiss) and freshwater turtle (trachemys scripta). the atpase rate was assessed by recording the rephosphorylation of adp by the pyruvate kinase reaction alone or together with the amount of creatine formed, when myofibrillar bound creatine kinase was activated with phosphocreatine. the steady-state concentration of adp in the soluti ...	2008	18515165
adenosine modulates erk1/2, pi3k/akt, and p38mapk activation in the brain of the anoxia-tolerant turtle trachemys scripta.	the fate of cells under anoxic or ischemic stress is determined by intracellular signaling pathways including the mitogen-activated protein kinases (mapks) and phosphatidylinositol 3-kinase (pi3k/akt), which affect downstream members of the apoptotic cascade. the freshwater turtle trachemys scripta is extremely tolerant of anoxia, surviving up to 48 h at room temperature and for weeks at 3 degrees c in the complete absence of oxygen. we investigated the relationship between the neuroprotective p ...	2008	18506199
cardiac output and shunt during voluntary activity at different temperatures in the turtle, trachemys scripta.	red-eared slider turtles (trachemys scripta) were chronically instrumented with blood flow probes for a long-term study of voluntary behavior in an enriched laboratory setting. cardiovascular measures consisting of total cardiac output (q(tot)), pulmonary blood flow (q(pul)), systemic blood flow (q(sys)), net cardiac shunt (q(shunt)), heart rate (hr), and stroke volume (sv) were obtained during spontaneous activity at a constant body temperature (tb=2 degrees c) and at unstable (variable) t(b)'s ...	2008	14671716
photoreceptors and visual pigments in the red-eared turtle, trachemys scripta elegans.	absorbance spectra of cone outer segments and oil droplets were recorded microspectrophotometrically in the retina of the red-eared turtle, trachemys scripta elegans. there are four cone visual pigments, with lambda(max) = 617 nm (red sensitive), 515 nm (green sensitive), 458 nm (blue sensitive), and 372 nm (uv-sensitive). the red-sensitive pigment resides in single cones with red or orange oil droplets, and in both members of double cones. the principal member of the double cone contains an ora ...	2008	11925010
concentrations of persistent organic pollutants in plasma from two species of turtle from the tennessee river gorge.	persistent organic pollutants (pops) are characterized by their resistance to degradation, biomagnification, global transport, and adverse toxicological effects. the goal of this study was to determine baseline concentrations of several classes of pops, including polychlorinated biphenyls (pcbs), organochlorine pesticides, and polybrominated diphenyl ethers (pbdes) in two turtle species, the cumberland slider (trachemys scripta troosti) and the common musk turtle (sternotherus odoratus) from the ...	2009	19406450
phosphorylation of translation factors in response to anoxia in turtles, trachemys scripta elegans: role of the amp-activated protein kinase and target of rapamycin signalling pathways.	long-term survival of oxygen deprivation by animals with well-developed anoxia tolerance depends on multiple biochemical adaptations including strong metabolic rate depression. we investigated whether the amp-activated protein kinase (ampk) could play a regulatory role in the suppression of protein synthesis that occurs when turtles experience anoxic conditions. ampk activity and the phosphorylation state of ribosomal translation factors were measured in liver, heart, red muscle and white muscle ...	2009	19579060
topography of purkinje cells and other calbindin-immunoreactive cells within adult and hatchling turtle cerebellum.	the turtle's cerebellum (cb) is an unfoliated sheet, so the topography of its entire cortex can be easily studied physiologically by optical recordings. however, unlike the mammalian cb, little is known about the topography of turtle purkinje cells (pcs). here, topography was examined using calbindin-d(28k) immunohistochemistry of adult and hatchling turtles (trachemys scripta elegans, 2.5-15 cm carapace length). each cb was flattened between two sylgard sheets and fixed in paraformaldehyde. sec ...	2009	19548045
rapid decline in the concentrations of three yolk steroids during development: is it embryonic regulation?	maternally derived yolk steroids have been found to elicit both short-term and long-term effects on offspring phenotype. paradoxically, their effects can be strikingly specific given the often substantial concentrations present at oviposition, and they do not appear to uniformly affect all steroid-sensitive processes. to better understand the dynamics of yolk steroids across embryonic development, we quantified levels of progesterone, testosterone, and estradiol at 5-day intervals throughout dev ...	2009	19523390
perspectives in cell cycle regulation: lessons from an anoxic vertebrate.	the ability of an animal, normally dependent on aerobic respiration, to suspend breathing and enter an anoxic state for long term survival is clearly a fascinating feat, and has been the focus of numerous biochemical studies. when anoxia tolerant turtles are faced with periods of oxygen deprivation, numerous physiological and biochemical alterations take place in order to facilitate vital reductions in atp consumption. such strategies include reversible post-translational modifications as well a ...	2009	20514219
haemangioma in the oesophagus of a red-eared slider (trachemys scripta elegans).	a haemangioma developing in the wall of the oesophagus and protruding into its cavity is reported for the first time from a red-eared slider (trachemys scripta elegans). as the tumour mechanically hampered swallowing, the animal was unable to eat and consequently developed a poor condition. histopathology of the tumour revealed all characteristics of a haemangioma: the blood-filled blood-vessels having an irregular cross-section were lined with endothelial cells. claudin-5 immunohistochemical an ...	2009	19897452
the chelonian spinal nerve ganglia are a conglomerate of the spinal nerve ganglia proper and the sympathetic ganglia.	a tyrosine hydroxylase-immunoreactive cell mass is found in the caudal portion of the dorsal nerve ganglion of the red-eared slider, trachemys scripta elegans. the ganglion appears as a flat oval structure in the horizontal plane, where the major axis runs latero-medially, and the minor axis rostro-caudally in the ventral view. a communicating branch to the sympathetic chain diverges from the top of each tubercle which lies on the caudo-lateral side of the ganglion. a tyrosine hydroxylase- immun ...	2009	19468213
role of neuroglobin in regulating reactive oxygen species in the brain of the anoxia-tolerant turtle trachemys scripta.	neuroglobin (ngb) is an oxygen binding heme protein found in nervous tissue with a yet unclear physiological and protective role in the hypoxia-sensitive mammalian brain. here we utilized in vivo and in vitro studies to examine the role of ngb in anoxic and post-anoxic neuronal survival in the freshwater turtle. we employed semiquantitative rt-pcr and western blotting to analyze ngb mrna and protein levels in turtle brain and neuronally enriched cultures. ngb expression is strongly up-regulated ...	2009	19457091
nitric oxide increases myocardial efficiency in the hypoxia-tolerant turtle trachemys scripta.	nitric oxide (no) may influence cardiac mechanical performance relative to o2 consumption by depressing respiration rate and by affecting the excitation-contraction coupling. such effects of no should be particularly important during hypoxia in species such as the hypoxia-tolerant turtle trachemys scripta. in heart ventricle preparations from this species, the ratio of twitch force to o2 consumption increased by approximately 15% during full oxygenation and by approximately 60% during hypoxia in ...	2009	19282492
effects of propofol administered via the supravertebral sinus in red-eared sliders.	to characterize the effects of propofol administered at 10 and 20 mg/kg (4.5 and 9 mg/lb) via the supravertebral venous sinus in red-eared sliders (trachemys scripta).	2009	19210263
localization and regulation of a facilitative urea transporter in the kidney of the red-eared slider turtle (trachemys scripta elegans).	urea is the major excretory end product of nitrogen metabolism in most chelonian reptiles. in the present study, we report the isolation of a 1632 base pair cdna from turtle kidney with one open reading frame putatively encoding a 403-residue protein, the turtle urea transporter (turtle ut). the first cloned reptilian ut has high homology with uts (facilitated urea transporters) cloned from vertebrates, and most closely resembles the ut-a subfamily. injection of turtle ut crna into xenopus oocyt ...	2009	19112144
steroid signaling and temperature-dependent sex determination-reviewing the evidence for early action of estrogen during ovarian determination in turtles.	the developmental processes underlying gonadal differentiation are conserved across vertebrates, but the triggers initiating these trajectories are extremely variable. the red-eared slider turtle (trachemys scripta elegans) exhibits temperature-dependent sex determination (tsd), a system where incubation temperature during a temperature-sensitive period of development determines offspring sex. however, gonadal sex is sensitive to both temperature and hormones during this period-particularly estr ...	2009	18992835
alien invasive slider turtle in unpredicted habitat: a matter of niche shift or of predictors studied?	species distribution models (sdms) aim on the characterization of a species' ecological niche and project it into geographic space. the result is a map of the species' potential distribution, which is, for instance, helpful to predict the capability of alien invasive species. with regard to alien invasive species, recently several authors observed a mismatch between potential distributions of native and invasive ranges derived from sdms and, as an explanation, ecological niche shift during biolo ...	2009	19956684
daily and seasonal rhythms in the respiratory sensitivity of red-eared sliders (trachemys scripta elegans).	the purpose of the present study was to determine whether the daily and seasonal changes in ventilation and breathing pattern previously documented in red-eared sliders resulted solely from daily and seasonal oscillations in metabolism or also from changes in chemoreflex sensitivity. turtles were exposed to natural environmental conditions over a one year period. in each season, oxygen consumption, ventilation and breathing pattern were measured continuously for 24 h while turtles were breathing ...	2009	19801438
effects of opioid receptor activation on thermal antinociception in red-eared slider turtles (trachemys scripta).	to determine the effects of mu-, delta-, and kappa-opioid receptor (mor, dor, and kor, respectively) activation on thermal antinociception in red-eared slider turtles trachemys scripta.	2009	19719421
correlation of cardiac performance with cellular energetic components in the oxygen-deprived turtle heart.	the relationship between cardiac energy metabolism and the depression of myocardial performance during oxygen deprivation has remained enigmatic. here, we combine in vivo (31)p-nmr spectroscopy and mri to provide the first temporal profile of in vivo cardiac energetics and cardiac performance of an anoxia-tolerant vertebrate, the freshwater turtle (trachemys scripta) during long-term anoxia exposure (approximately 3 h at 21 degrees c and 11 days at 5 degrees c). during anoxia, phosphocreatine (p ...	2009	19587113
reptilian heart development and the molecular basis of cardiac chamber evolution.	the emergence of terrestrial life witnessed the need for more sophisticated circulatory systems. this has evolved in birds, mammals and crocodilians into complete septation of the heart into left and right sides, allowing separate pulmonary and systemic circulatory systems, a key requirement for the evolution of endothermy. however, the evolution of the amniote heart is poorly understood. reptilian hearts have been the subject of debate in the context of the evolution of cardiac septation: do th ...	2009	19727199
a modified yolk biopsy technique improves survivorship of turtle eggs.	nongenetic maternal contributions, such as steroid hormones, have received much attention in recent years because they have the potential to influence offspring phenotype. research in oviparous taxa has demonstrated that there is among-species variability in their response to these maternal contributions. however, studies in chelonians and crocodilians have been hampered by the fact that techniques involving egg manipulations that breach the eggshell routinely result in massive egg mortality. in ...	2009	19193061
lung ventilation during treadmill locomotion in a semi-aquatic turtle, trachemys scripta.	it is reasonable to presume that locomotion should have a mechanical effect on breathing in turtles. the turtle shell is rigid, and when the limbs protract and retract, air in the lungs should be displaced. this expectation was met in a previous study of the green sea turtle, chelonia mydas; breathing completely ceased during terrestrial locomotion (jackson and prange, 1979. j comp physiol 134:315-319). in contrast, another study found no direct effect of locomotion on ventilation in the terrest ...	2009	18623107
helminth communities of the exotic introduced turtle, trachemys scripta elegans in southwestern spain: transmission from native turtles.	we report the prevalence and diversity of helminth parasites found in native turtles mauremys leprosa and emys orbicularis from three localities in southwestern spain and we describe the helminth communities of exotic turtles trachemys scripta elegans coexisting in the wild with both native turtle species. five nematodes species were identified, of which serpinema microcephalus was the only species common between two localities, although infection parameters were different between them. this is ...	2009	18799176
salt intake and plasma renin activity in the freshwater turtle.	in mammals, a well-documented inverse relationship exists between oral salt intake and plasma renin activity (pra). we carried out this study to determine if a similar relationship exists in the freshwater turtle pseudemys scripta. three groups of turtles (n = 8 for each group) were fed different amounts of salt dissolved in distilled water (2 cc/kg). the high salt group received 580 mg (10 meq) nacl/kg twice per week, the medium salt group received 290 mg (5 meq) nacl/kg twice per week, and the ...	2009	2684740
[non-indigenous and non-specific parasitic nematodes--the background and the consequences].	introduction of the host is the main reason behind introduction of the parasite, e. g., nematodes. the introduction of the japanese eel (anguilla japonica) in europe in the 1980s resulted in expansion of the swimbladder nematode anguillicola crassus which soon invaded not only populations of the european eel (a. anguilla), but also other local fish. the raccoon (procyon lotor) is native to north america. it is the specific host of strongyloides procyonis and baylisascaris procyonis. more than 90 ...	2009	20209803
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
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
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