| plasma levels of vitellogenin in chrysemys picta during the annual gonadal cycle: measurement by specific radioimmunoassay. | a ria for turtle (chrysemys picta) vitellogenin is described. after dimethylformamide precipitation of vitellogenin from the plasma of estrogen-treated female turtles, antibodies were developed in rabbits. the dimethylformamide precipitate was further purified by o-triethylaminoethyl cellulose column chromatography; the vitellogenin component eluted as a single peak. this material was used for iodination by a mild chloramine method. antibodies to turtle vitellogenin did not cross-react with plas ... | 1979 | 108085 |
| the influence of mammalian and avian gonadotropins on in vitro ovarian steroid synthesis in the turtle (chrysemys picta). | | 1976 | 179912 |
| gonadotropin action and androgen synthesis in enzyme disperesed testicular cells of the turtle (chrysemys picta). | | 1977 | 195861 |
| plasma testosterone levels in male turtles, chrysemys picta, following single injections of mammalian, avian and teleostean gonadotropins. | | 1977 | 195862 |
| optokinetic nystagmus and the accessory optic system of pigeon and turtle. | optokinetic nystagmus (okn) response functions were obtained in pigeon (columba livia) and turtle (chrysemys picta) before and after electrolytic lesions of the accessory optic nuclei (aon). postlesion retinal input to the aon was evaluated using standard autoradiographic techniques. bilateral destruction of aon in both pigeon and turtle did not abolish okn, but was correlated instead with a reduction in okn frequencies at high pattern velocities. a difference was observed between species with r ... | 1979 | 487063 |
| identification of aromatase in the reptilian brain. | the present study tests the hypothesis that brain aromatase is an "ancient" property of nervous tissue and may be identified in homologues of the limbic system in a non-mammalian vertebrate, the turtle chrysemys picta. tissue homogenates (180 mg wet weight/2 ml) were incubated with [7 alpha-3h]androstenedione and cofactors for 60 min at 37 c. estrone (e1) was isolated and characterized by thin layer chromatography, methylation and recrystallization to constant specific activity. no estradiol-17 ... | 1977 | 837883 |
| the effects of hormones on the reproductive physiology of the painted turtle, chrysemys picta. | | 1977 | 881114 |
| antileptospiral activity in lower-vertebrate sera. | normal serum from the painted turtle (chrysemys picta), the snapping turtle (chelydra serpentina), and the frog (rana pipiens) were found to possess bactericidal activity towards leptospira. leptospires from both the parasitic and biflexa complexes were killed by these sera at high dilutions. this pattern differs from that of mammalian serum, as generally only the biflexa complex leptospires are killed by normal mammalian serum. the activity in c. picta serum was characterized as being complemen ... | 1975 | 1081972 |
| putative apolipoprotein b-100 in the freshwater turtle chrysemys picta: effects of estrogen and progesterone. | 1. the isolation and purification of a putative apolipoprotein b-100 in the plasma of the freshwater turtle chrysemys picta is described. 2. the protein was purified through differential ultracentrifugation and subsequent sepharose 6b column chromatography. 3. the molecular weight of the protein determined by electrophoresis was approximately 350 kda. 4. an antibody to chicken apolipoprotein b-100 specifically recognizes this 350 kda protein in western blots, suggesting its identity with apolipo ... | 1992 | 1458844 |
| life in a frozen state: adaptive strategies for natural freeze tolerance in amphibians and reptiles. | winter survival for various species of amphibians and reptiles that hibernate on land depends on freeze tolerance, the ability to survive for long periods of time with up to 65% of total body water as extracellular ice. freeze tolerance has been described for four species of frogs, one salamander, and hatchlings of the painted turtle. a very limited tolerance also occurs in garter snakes. studies of freeze tolerance in vertebrates have primarily focused on the wood frog rana sylvatica and have a ... | 1990 | 2180324 |
| a simplified model for bivariate complex allometry. | a three-parameter relationship passing through the origin can be derived from the gompertz growth curve and provide a simplified but useful description of complex allometry, where variates are not proportional to powers of each other as in simple allometry. partial linearization is often satisfactory and, after a double logarithmic transformation, the allometric relationship is non-linear only with respect to an exponent of complex allometry, d, which reflects the presence (e # 1) or absence (d ... | 1989 | 2615392 |
| nuclear acceptor sites for estrogen-receptor complexes in the liver of the turtle, chrysemys picta. i. sexual differences, species specificity and hormonal dependency. | hepatic estrogen receptors (ers) of the female turtle, chrysemys picta, when complexed with [3h]estradiol ([3h]e2), were shown to bind specifically to liver chromatin isolated from the same species. the binding of the [3h]e2 receptor complex to chromatin requires both the steroid ligand and the receptor protein. maximal binding occurred within 60-70 min of incubation at 4 degrees c in a tris buffer containing 0.1 m kcl. the binding of the [3h]e2 receptor complex to intact chromatin was saturable ... | 1989 | 2744216 |
| immune response in the turtle (chrysemys picta). | | 1972 | 4114647 |
| adenosine triphosphatase activity of heart mitochondria of the turtle, chrysemys picta. | | 1970 | 4249480 |
| de lange characteristics for the fresh-water turtle chrysemys picta picta, and the pigeon columba livia. | | 1973 | 4746984 |
| life cycle and pathology of spirorchis scripta stunkard, 1923 (digenea: spirorchiidae) in chrysemys picta picta. | | 1968 | 5647114 |
| effects of synthetic mammalian thyrotrophin releasing hormone, somatostatin and dopamine on the secretion of prolactin and growth hormone from amphibian and reptilian pituitary glands incubated in vitro. | pituitary glands of grassfrog (rana pipiens), bullfrog (rana catesbeiana), clawed toad (xenopus laevis) and two species of terrapin (chrysemys picta and pseudemys scripta) were incubated in medium containing hypothalamic extract (he), thyrotrophin releasing hormone (trh), somatostatin, dopamine, or combinations of these treatments. prolactin and gh concentrations in the medium were determined by densitometry after polyacrylamide-gel electrophoretic separation. hypothalamic extract stimulated sec ... | 1984 | 6146654 |
| herpesvirus-like infection in a painted turtle (chrysemys picta). | a painted turtle (chrysemys picta) which died in captivity had marked necrosis in the liver and lungs with numerous intranuclear inclusion bodies in hepatocytes and respiratory epithelial cells. electron microscopy revealed herpesvirus-like particles in cells in affected tissues. | 1980 | 6251285 |
| susceptibility of two turtle species to eastern equine encephalitis virus. | two species of turtle collected in southern new england were inoculated subcutaneously with eastern equine encephalitis virus. the spotted turtles (clemmys guttata) developed viremia and neutralizing antibody after exposure to 3 logs or more of virus. viremia was not detected in the eastern painted turtles (chrysemys picta), and neutralizing antibody was detected in only 1 of 15 inoculated c. picta; however, since pre-inoculation serum was not obtained from this animal, the possibility of natura ... | 1980 | 6257935 |
| role of adenosine in nmda receptor modulation in the cerebral cortex of an anoxia-tolerant turtle (chrysemys picta belli). | accumulation of the neuromodulator adenosine in the anoxia-tolerant turtle brain may play a key role in a protective decrease in excitatory neurotransmission during anoxia. since excitatory neurotransmission is mediated largely by ca2+ entry through n-methyl-d-aspartate (nmda) receptors, we measured the effect of adenosine on nmda-mediated ca2+ transients in normoxic and anoxic turtle cerebrocortical sheets. intracellular [ca2+] was measured fluorometrically with the ca2+-sensitive dye fura-2. b ... | 1995 | 7658192 |
| photoaffinity labeling of the ah receptor: phylogenetic survey of diverse vertebrate and invertebrate species. | the mammalian aromatic hydrocarbon (ah) receptor is a soluble protein involved in the regulation of gene expression by halogenated aromatic hydrocarbons such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (tcdd). little is known, however, about the presence and properties of this receptor in nonmammalian species. in these studies, we sought evidence for an ah receptor in the liver or liver-equivalent of diverse species of invertebrate and vertebrate animals. velocity sedimentation analysis of hepatic cy ... | 1994 | 8161208 |
| vitellogenin induction in painted turtle, chrysemys picta, as a biomarker of exposure to environmental levels of estradiol. | ponds within cattle farms often support turtle and fish populations and are impacted by manure runoff. cattle excrete metabolized (glucuronide-conjugated) hormones in feces and urine into these ponds, and bacteria cleave the glucuronide metabolites to active steroids, which can be stable for several weeks in wastewater. the objectives of this study were to (1) assess levels of xenoestrogens found in ponds near livestock pastures; and (2) assess whether these levels of xenoestrogens induce vitell ... | 2001 | 11551621 |
| morbidity and mortality of reptiles admitted to the wildlife center of virginia, 1991 to 2000. | medical records from 694 reptiles admitted to the wildlife center of virginia (wcv; waynesboro, virginia, usa) from 1991 to 2000 were reviewed to determine causes of morbidity and mortality. eighteen species were represented but the majority of cases were four species; eastern box turtle (terrapene carolina) (66%), eastern painted turtle (chrysemys picta) (11%), common snapping turtle (chelydra serpentina) (10%), and rat snake (elaphe sp.) (6%). there was a significant increase in reptile cases ... | 2002 | 12528435 |
| 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 |
| activation of antioxidant defenses in response to freezing in freeze-tolerant painted turtle hatchlings. | hatchlings of the painted turtle, chrysemys picta marginata can endure long-term freezing of their extracellular body fluids. we hypothesized that freezing survival would include adaptive up-regulation of antioxidant defenses to deal with ischemia-reperfusion injuries associated with the freeze-thaw cycle. a number of antioxidant enzymes are under the control of the nf-e2 related factor 2 (nrf2) transcription factor including members of the glutathione s-transferase (gst) and aldo-keto reductase ... | 2010 | 20359523 |
| evidence for gabaergic interneurons in the red nucleus of the painted turtle. | immunocytochemical and electrophysiological evidence supporting the presence of gabaergic interneurons in the turtle red nucleus is presented. injections of hrp into the spinal cord produced labeling of large neurons in the contralateral red nucleus. the peroxidase-antiperoxidase (pap) method revealed smaller cells immunoreactive to an antibody against glutamate decarboxylase (gad), the synthetic enzyme for the inhibitory neurotransmitter gaba, that were interspersed among larger immunonegative ... | 2006 | 1636150 |
| phylogenomic investigation of cr1 line diversity in reptiles. | it is unlikely that taxonomically diverse phylogenetic studies will be completed rapidly in the near future for nonmodel organisms on a whole-genome basis. however, one approach to advancing the field of "phylogenomics" is to estimate the structure of poorly known genomes by mining libraries of clones from suites of taxa, rather than from single species. the present analysis adopts this approach by taking advantage of megabase-scale end-sequence scanning of reptilian genomic clones to characteri ... | 2006 | 17345672 |
| reproductive deficits in male freshwater turtle chrysemys picta from cape cod, massachusetts. | contaminated groundwater plumes have formed on the massachusetts military reservation (mmr), a superfund site on cape cod, massachusetts, as a result of chemical waste disposal. the plumes are of concern to the local people who rely on groundwater as a drinking water source. we used the freshwater turtle as a sentinel species to monitor the reproductive effects of exposure and, by inference, the potential for impact on human health. our observations of male chrysemys picta field-trapped from moo ... | 2007 | 17123946 |
| avenues of extrapulmonary oxygen uptake in western painted turtles (chrysemys picta belli) at 10 degrees c. | the major avenues of extrapulmonary oxygen uptake were determined on submerged western painted turtles (chrysemys picta bellii) at 10 degrees c by selectively blocking one or more potential pathways for exchange. previous work indicated that the skin, the cloaca, and the buccopharyngeal cavity can all contribute significantly in various species of turtles. o(2) uptake was calculated from the rate of fall in water p(o(2)) in a closed chamber. two series of experiments were conducted: in series 1, ... | 2004 | 15528171 |
| bacterial infection and tissue-specific hsp72, -73 and -90 expression in western painted turtles. | heat shock proteins (hsps) are molecular chaperones that assist intracellular folding, assembly and translocation of proteins in prokaryotic and eukaryotic cells. a variety of stresses including hyperthermia, radiation, heavy metals, ischemia, anoxia and reoxygenation have been shown to increase the expression of hsps. likewise, bacterial infection represents a stress for the host cell. in this study, expression of the constitutive (hsp73) and inducible (hsp72) isoforms of hsp70 and hsp90 was mo ... | 2004 | 15450861 |
| characterization of the testicular binding site for iodinated rat fsh in the turtle, chrysemys picta. | 1. to correlate the morphological observations with the known gonadotropic activity of fsh in the turtle testis, studies of the binding of iodinated fsh were conducted. 2. these demonstrated the presence of gonadotropin-binding sites of high affinity (apparent kd = 10(-10) m) for [125i]rfsh in turtle testicular membrane preparations. 3. although these sites did not bind iodinated human lh or avian lh, these hormones, as well as pmsg and fsh, were effective competitive inhibitors of the binding o ... | 1985 | 14577399 |
| seasonal changes in hepatic progesterone receptor mrna, estrogen receptor mrna, and vitellogenin mrna in the painted turtle, chrysemys picta. | previous studies using the fresh water turtle chrysemys picta have demonstrated that progesterone (p) inhibits estradiol (e)-induced vitellogenin (vtg) secretion in this species. further, there is evidence for the differential expression of the two p receptor isoforms (pra and prb) in the liver during the turtle seasonal cycle, correlating with hepatic vitellogenesis. in this study we report changes in the hepatic pr mpna, er mrna, and vitellogenin (vtg) mrna transcripts during the reproductive ... | 2002 | 12392693 |
| expression of sr-bi (scavenger receptor class b type i) in turtle (chrysemys picta) tissues and other nonmammalian vertebrates. | in this study, the tissue distribution of the expression of an hdl-receptor (sr-bi; scavenger receptor class b type i) was investigated in the turtle using an antiserum to murine sr-bi. several turtle tissues including liver, heart, small intestine, kidney, oviduct, ovary, and testis were shown to express an 82 kda membrane protein. in addition, sr-bi expression in livers of other nonmammalian species such as the chicken, frog, goldfish, shark, and skate is also reported. ovarian sr-bi expressio ... | 2002 | 11857477 |
| molecular decay of enamel matrix protein genes in turtles and other edentulous amniotes. | secondary edentulism (toothlessness) has evolved on multiple occasions in amniotes including several mammalian lineages (pangolins, anteaters, baleen whales), birds, and turtles. all edentulous amniote clades have evolved from ancestors with enamel-capped teeth. previous studies have documented the molecular decay of tooth-specific genes in edentulous mammals, all of which lost their teeth in the cenozoic, and birds, which lost their teeth in the cretaceous. by contrast with mammals and birds, t ... | 2013 | 23342979 |
| experimental feeding of hydrilla verticillata colonized by stigonematales cyanobacteria induces vacuolar myelinopathy in painted turtles (chrysemys picta). | vacuolar myelinopathy (vm) is a neurologic disease primarily found in birds that occurs when wildlife ingest submerged aquatic vegetation colonized by an uncharacterized toxin-producing cyanobacterium (hereafter "ucb" for "uncharacterized cyanobacterium"). turtles are among the closest extant relatives of birds and many species directly and/or indirectly consume aquatic vegetation. however, it is unknown whether turtles can develop vm. we conducted a feeding trial to determine whether painted tu ... | 2014 | 24695109 |
| 3,3',4,4'-tetrachlorobiphenyl oxidation in fish, bird and reptile species: relationship to cytochrome p450 1a inactivation and reactive oxygen production. | previously we showed that the polychlorinated biphenyl 3,3',4,4'-tetrachlorobiphenyl (tcb) caused a release of reactive oxygen species (ros) from cytochrome p450 1a (cyp1a) of the fish scup (stenotomus chrysops), and from rat and human cyp1a1. this was linked to a tcb- and nadph-dependent oxidative inactivation of the enzyme, which in scup and rat was inversely related to the rates of tcb oxidation. we examined the relationship between rates of tcb oxidation, cyp1a inactivation and ros productio ... | 2000 | 11790349 |
| immunocytochemical localization of glutamate receptor subunits in the brain stem and cerebellum of the turtle chrysemys picta. | the regional distribution of ionotropic (ampa and nmda) and metabotropic (mglur1alpha) glutamate receptor subunits was examined in the brain stem and cerebellum of the pond turtle, chrysemys picta, by using immunocytochemistry and light microscopy. subunit-specific antibodies that recognize nmdar1, glur1, glur4, and mglur1alpha were used to identify immunoreactive nuclei in the brain stem and cerebellum. considerable immunoreactivity in the turtle brain stem and cerebellum was observed with regi ... | 2000 | 11054706 |
| expression of heat shock proteins in turtle and mammal hearts: relationship to anoxia tolerance. | heat shock proteins (hsps) may play a cardioprotective role during hypoxia or ischemia. we hypothesized that cardiac tissue from hypoxia-tolerant animals might have high levels of specific hsps. we measured myocardial hsp60 and hsp72/73 in painted and softshell turtles during normoxia and anoxia (12 h) and after recovery (12 or 24 h). we also measured myocardial hsps in normoxic rats and rabbits. during normoxia, hearts from the most highly anoxia-tolerant species, the painted turtle, expressed ... | 2000 | 10644641 |
| comparison of cortically and subcortically controlled motor systems. ii. distribution of anterogradely labeled terminal boutons on intracellularly filled rubrospinal neurons in rat and turtle. | the present study examined the circuitry of the red nucleus of the sprague-dawley rat and the freshwater pond turtle, chrysemys picta, by using intracellular cell filling combined with anterograde tract tracing. although both species have a well-developed cerebellorubral system, they differ in that the red nucleus of rats receives direct input from the motor areas of the cerebral cortex, whereas turtles do not. however, a direct descending projection from the hypothalamus to the red nucleus of t ... | 2000 | 10578105 |
| cytochromes p450 in liver of the turtle chrysemys picta picta and the induction and partial purification of cyp1a-like proteins. | cytochromes p450 (cyp) in hepatic microsomes from the turtle chrysemys picta picta and their response to inducers were examined. freshly caught turtles had one protein (59 kda) detected in western blot with monoclonal antibody 1-12-3 to scup cyp1a. that same band and a second band were detected with polyclonal anti-mouse cyp1a1. polyclonal anti-scup p450b (putative cyp2b) recognized three bands and anti-scup p450a (putative cyp3a), one band. tcb (3,3',4,4'-tetrachlorobiphenyl) at 5 mg kg-1 injec ... | 1998 | 9659368 |
| substrate and acute temperature effects on turtle heart and liver mitochondria. | the oxidative properties of heart and liver mitochondria from the western painted turtle (chrysemys picta bellii) were characterized on the basis of substrate preferences and temperature sensitivity. turtle heart and liver mitochondria oxidize most substrates at 2- and 10-fold less, respectively, than rates obtained from the corresponding rat mitochondria. krebs cycle intermediates, ketone bodies, and glutamate were oxidized at similarly high rates by turtle heart mitochondria (70.0-121.2 nmol o ... | 1994 | 8160881 |
| distribution and characterization of apolipoproteins in chrysemys picta plasma. | very low density lipoproteins (vldl) (d < 1.006), low density lipoproteins (ldl) (1.006 < d < 1.063), and high density lipoproteins (hdl) (1.063 < d < 1.21) were isolated by ultracentrifugation from the plasma of female and male chrysemys picta. the protein components of lipoproteins (apolipoproteins) were analysed by electrophoresis in denaturing polyacrylamide gradient gel. gel filtration chromatography, electroelution from gradient gel and two dimensional electrophoresis were utilized to part ... | 1995 | 7584832 |
| seasonal cycles in testicular activity, gonadotropin, and thyroxine in the painted turtle, chrysemys picta, under natural conditions. | plasma levels of testosterone (t), thyroxine (t4) and follicle-stimulating hormone (fsh) were measured in a field population of the painted turtle, chrysemys picta, in michigan. all three hormones showed pronounced seasonality; plasma luteinizing hormone (lh) remained nondetectable. plasma t and fsh concentrations were highly correlated and exhibited biphasic cycles with peaks in spring and fall, whereas t4 showed a single peak in summer, coincident with the nadir in t. hormone levels were minim ... | 1985 | 3926601 |
| specificity of amphibian and reptilian pituitaries for various forms of gonadotropin-releasing hormones in vitro. | in vitro perifusion was employed to compare the potencies of mammalian, avian, salmon, and lamprey gonadotropin-releasing hormones (gnrhs) on the release of luteinizing hormone (lh) from the pituitaries of an amphibian (rana pipiens) and a reptile (chrysemys picta). the chicken-i and salmon gnrh variants were equipotent with mammalian gnrh in both the frog and the turtle glands. by contrast, the lamprey gnrh was inactive (less than 1% as potent as the others). lamprey gnrh also failed to stimula ... | 1987 | 3556314 |
| riboflavin-binding protein from reptiles: a comparison with avian riboflavin-binding proteins. | 1. riboflavin-binding protein (rbp) has been isolated for the first time from reptilian sources. 2. rbp from eggs of python molurus (indian python) and chrysemys picta (painted turtle) has been isolated and compared to rbp from gallus gallus domesticus (chicken), a well-characterized protein, and a newly isolated rbp from cairina moschata (muscovy duck). 3. each of the proteins is phosphorylated and glycosylated. 4. the ratio of riboflavin binding to protein is 1:1 and the kd for each protein is ... | 1988 | 3396329 |
| the effects of cold acclimation on electrocardiogram parameters in five species of turtles. | the effects of thermal acclimation at 25 or 5 degrees c on electrical activity in the heart were investigated in pseudemys scripta, terrapene carolina, chrysemys picta marginata, chrysemys picta dorsalis, chelydra serpentina, and sternotherus odoratus. the durations of the qrs complex and p-r, r-t and r-r intervals were found to increase with decreasing body temperature in all animals tested. the amplitudes of the p and t waves and qrs complex were dependent upon both acclimation temperature and ... | 1987 | 2886260 |
| cloned rainbow trout liver p(1)450 complementary dna as a potential environmental monitor. | a technique is proposed for the biological monitoring of pollutants in aquatic environments by use of a complementary dna (cdna) probe. the induction of hepatic cytochrome p(1)450 mrna has been investigated utilizing pfp(1)450-3', a 3'-specific 1.5 kb cdna clone derived from 3-methylcholanthrene-inducible mrna of rainbow trout. a time course of induction of both the hybridizable mrna and hepatic monooxygenase catalytic activity in rainbow trout with a known inducer in fish, beta-naphthoflavone, ... | 1989 | 2711397 |
| hepatic progesterone receptors: characterization in the turtle chrysemys picta. | high and low affinity progesterone (p)-binding proteins similar to those described in the chick oviduct were characterized for the first time in liver cytosol in an oviparous turtle, chrysemys picta. two forms of high affinity p receptor were separated by diethyl aminoethyl (deae)-sepharose anion exchange chromatography; the a form eluted in low salt buffer, and the b form at a kcl concentration of 0.20 m in a linear gradient. after photoaffinity labeling of crude cytosol with [3h] r5020, two ov ... | 2012 | 3396503 |
| 31p-nmr study of normoxic and anoxic perfused turtle heart during graded co2 and lactic acidosis. | we studied the effects of graded acidosis (both co2 and lactic acid) and anoxia on intracellular ph (phi) regulation, high-energy phosphates, and mechanical function of isolated perfused hearts of the turtle (chrysemys picta bellii) at 20 degrees c using 31p-nuclear magnetic resonance (nmr) spectroscopy. during co2 acidosis, anoxia had no effect on apparent nonbicarbonate buffer value (d[hco3-]/dphi = 71 and 89 mm/ph in normoxia and anoxia, respectively) or on phi regulation (dphi/dphe = 0.52 an ... | 2006 | 1905494 |
| changes in ventilation and breathing pattern produced by changing body temperature and inspired co2 concentration in turtles. | respiratory minute ventilation (ve), breathing pattern, oxygen consumption (vo2) and arterial blood gases and ph were measured in freshwater turtles (chrysemys picta) at 10, 20 and 30 degrees c while the animals breathed gases of varying co2 concentration (fico2 = 0, 2, 4, 6 and 8%). increasing body temperature produced unequal increases in ve and vo2 such that ve/vo2 decreased. this relative hypoventilation led to a rise in paco2 and fall in pha. increasing fico2 at all temperatures greatly ele ... | 2011 | 3103185 |
| Incidental nest predation in freshwater turtles: inter- and intraspecific differences in vulnerability are explained by relative crypsis. | There has long been interest in the influence of predators on prey populations, although most predator-prey studies have focused on prey species that are targets of directed predator searching. Conversely, few have addressed depredation that occurs after incidental encounters with predators. We tested two predictions stemming from the hypothesis that nest predation on two sympatric freshwater turtle species whose nests are differentially prone to opportunistic detection-painted turtles (Chrysemy ... | 2011 | 22009341 |
| the painted turtle, chrysemys picta: a model system for vertebrate evolution, ecology, and human health. | painted turtles (chrysemys picta) are representatives of a vertebrate clade whose biology and phylogenetic position hold a key to our understanding of fundamental aspects of vertebrate evolution. these features make them an ideal emerging model system. extensive ecological and physiological research provide the context in which to place new research advances in evolutionary genetics, genomics, evolutionary developmental biology, and ecological developmental biology which are enabled by current r ... | 2009 | 20147199 |
| genome evolution in reptilia: in silico chicken mapping of 12,000 bac-end sequences from two reptiles and a basal bird. | with the publication of the draft chicken genome and the recent production of several bac clone libraries from non-avian reptiles and birds, it is now possible to undertake more detailed comparative genomic studies in reptilia. of interest in particular are the genomic events that transformed the large, repeat-rich genomes of mammals and non-avian reptiles into the minimalist chicken genome. we have used paired bac end sequences (bess) from the american alligator (alligator mississippiensis), pa ... | 2009 | 19607659 |
| lh secretion in response to gonadotropin releasing hormone (gnrh) by superfused pituitaries from two species of turtles. | a superfusion system was employed to study the dynamics of the responses of lh secretion to gonadotropin releasing hormone (gnrh) by anterior pituitary glands (quartered) from adult turtles, pseudemys scripta and chrysemys picta. responsiveness was highly variable in both species, but in many cases, the tissues showed marked responses to relatively low doses (2-20 ng/ml) of gnrh. gnrh had no effect on lh secretion in five female p. scripta tested in the month of august, whereas it stimulated mos ... | 2014 | 3899857 |
| two progesterone receptors in the oviduct of the freshwater turtle chrysemys picta: possible homology to mammalian and avian progesterone receptor systems. | two progesterone receptors in the oviduct of the freshwater turtle chrysemys picta: possible homology to mammalian and avian receptor systems. here we report the characterization of two specific progesterone receptors in nuclear extracts of the turtle oviduct. the receptors differ in dissociation constants (2.8 nm vs 27 nm) which can be separated on deae-sepharose, the former eluting at 0.08 m kcl and the latter at 0.20 m kcl. [3h]r5020 photoaffinity labeling sds-page revealed that the 2.8 nm mo ... | 2009 | 2770302 |
| effect of hypophysectomy on renal function in the western painted turtle (chrysemys picta belli). | | 2015 | 4649159 |
| high-affinity binding of [3h]estradiol-17 beta by an estrogen receptor in the liver of the turtle. | specific [3h]estradiol-17 beta ([3h]e2) binding activity (eba) with characteristics of an estrogen receptor (er) was demonstrated in cytosols and nuclear extracts of the female turtle, chrysemys picta. three different receptor assays (dextran-coated charcoal assay, hydroxylapatite batch procedure, and dna-cellulose chromatography) were evaluated in terms of their applicability in analyzing large numbers of samples. for the measurement of cytosolic eba, the hydroxylapatite batch procedure was fou ... | 2010 | 3417113 |
| control of the interrenal gland of the freshwater turtle chrysemys picta in vivo and in vitro. | | 2003 | 166009 |
| oxidative cost of breathing in the turtle chrysemys picta bellii. | we estimated the cost of breathing of turtles by measuring ventilation and oxygen consumption during air breathing and co2 breathing. we assumed that any increment in oxygen consumption due to hypercapnic hyperpnea was due to the metabolic cost of the increased breathing. six turtles were studied while breathing air and then 5% co2 in air after at least 12 h breathing each gas. for the measurements, the turtles were submerged unrestrained in water at 20 degrees c and were free to raise their hea ... | 2007 | 1951782 |
| 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 |
| demonstrating the value and importance of combining dna barcodes and discriminant morphological characters for polystome taxonomy (platyhelminthes, monogenea). | polystomes are monogenean parasites that infest mainly semi aquatic vertebrates, such as amphibians and chelonians. owing to the lack of discriminative morphological characters and because polystomes are considered to be strictly host- and site-specific, host identity is often used as an additional character for parasite identification. recent genetic studies, however, showed that polystomes infecting freshwater turtles in outdoor turtle enclosures and natural environments, were not strictly hos ... | 2017 | 28336417 |
| postembryonic nephrogenesis and persistence of six2-expressing nephron progenitor cells in the reptilian kidney. | new nephron formation (nephrogenesis) ceases in mammals around birth and is completely absent in adults. in contrast, postembryonic nephrogenesis is well documented in the mesonephric kidneys of fishes and amphibians. the transient mesonephros in reptiles (including birds) and mammals is replaced by the metanephros during embryogenesis. thus, one may speculate that postembryonic nephrogenesis is restricted to the mesonephric kidney. previous reports have suggested the metanephros of non-avian re ... | 2016 | 27144443 |
| new resources inform study of genome size, content, and organization in nonavian reptiles. | genomic resources for studies of nonavian reptiles have recently improved and will reach a new level of access once the genomes of the painted turtle (chrysemys picta) and the green anole (anolis carolinensis) have been published. eleven speakers gathered for a symposium on reptilian genomics and evolutionary genetics at the 2008 meeting of the society for integrative and comparative biology in san antonio, texas. presentations described results of reptilian genetic studies concerning molecular ... | 2008 | 21669805 |
| transcriptomic responses to environmental temperature by turtles with temperature-dependent and genotypic sex determination assessed by rnaseq inform the genetic architecture of embryonic gonadal development. | vertebrate sexual fate is decided primarily by the individual's genotype (gsd), by the environmental temperature during development (tsd), or both. turtles exhibit tsd and gsd, making them ideal to study the evolution of sex determination. here we analyze temperature-specific gonadal transcriptomes (rna-sequencing validated by qpcr) of painted turtles (chrysemys picta tsd) before and during the thermosensitive period, and at equivalent stages in soft-shell turtles (apalone spinifera-gsd), to tes ... | 2017 | 28296881 |
| anatomy of the fully formed chondrocranium of emydura subglobosa (chelidae): a pleurodiran turtle. | the chondrocranium is a cartilaginous structure that forms around and protects the brain and sensory organs of the head. through ontogeny, this skeletal structure may become more elaborate, remodeled and reabsorbed, and/or ossified. though considerable attention has been given to the formation of the chondrocranium and a great amount of data has been gathered on the development of this structure among many craniates, the anatomy of this structure in turtles often is neglected. we describe the ma ... | 2013 | 22972700 |
| protamines of reptiles. | we have characterized for the first time the complete primary structure of the main protamine components of the sperm from four reptiles: chrysemys picta (turtle), elaphe obsoleta (snake), anolis carolinensis (lizard), and alligator mississipiensis (crocodilian). these species were chosen to represent one of each of the main phylogenetic branches of this taxonomic group. comparison of these protamine sequences with those already available from other vertebrate groups allows us to define properly ... | 1996 | 8798564 |
| ontogenetic shifts in the diet of plains hog-nosed snakes (heterodon nasicus) revealed by stable isotope analysis. | wild snake diets are difficult to study using traditional methods, but stable isotopes offer several advantages, including integrating dietary information over time, providing data from individuals that have not fed recently, and avoiding bias towards slowly-digesting prey items. we used stable isotope signatures of carbon and nitrogen from scale tissue, red blood cells, and blood plasma to assess the diet of wild plains hog-nosed snakes (heterodon nasicus) in illinois. we developed bayesian mix ... | 2017 | 27692795 |
| body burdens of heavy metals in lake michigan wetland turtles. | tissue heavy metal concentrations in painted (chrysemys picta) and snapping (chelydra serpentina) turtles from lake michigan coastal wetlands were analyzed to determine (1) whether turtles accumulated heavy metals, (2) if tissue metal concentrations were related to environmental metal concentrations, and (3) the potential for non-lethal sampling techniques to be used for monitoring heavy metal body burdens in freshwater turtles. muscle, liver, shell, and claw samples were collected from painted ... | 2016 | 26832725 |
| exogenous application of estradiol to eggs unexpectedly induces male development in two turtle species with temperature-dependent sex determination. | steroid hormones affect sex determination in a variety of vertebrates. the feminizing effects of exposure to estradiol and the masculinizing effects of aromatase inhibition during development are well established in a broad range of vertebrate taxa, but paradoxical findings are occasionally reported. four independent experiments were conducted on two turtle species with temperature-dependent sex determination (chrysemys picta and chelydra serpentina) to quantify the effects of egg incubation tem ... | 2014 | 24954686 |
| widespread reproductive variation in north american turtles: temperature, egg size and optimality. | theory predicts the existence of an optimal offspring size that balances the trade-off between offspring fitness and offspring number. however, in wild populations of many species, egg size can still vary from year to year for unknown reasons. here, we hypothesize that among-year variation in population mean egg size of freshwater turtles is partly a consequence of their gonadal sensitivity to seasonal temperatures, a physiological mechanism which principally functions to synchronize reproductio ... | 2012 | 22541670 |
| parent-offspring conflict and selection on egg size in turtles. | the trade-off between offspring size and number can present a conflict between parents and their offspring. because egg size is constrained by clutch size, the optimal egg size for offspring fitness may not always be equivalent to that which maximizes parental fitness. we evaluated selection on egg size in three turtle species (apalone mutica, chelydra serpentina and chrysemys picta) to determine if optimal egg sizes differ between offspring and their mothers. although hatching success was gener ... | 2009 | 19796084 |
| influence of feeding ecology on blood mercury concentrations in four species of turtles. | mercury is a relatively well-studied pollutant because of its global distribution, toxicity, and ability to bioaccumulate and biomagnify in food webs: however, little is known about bioaccumulation and toxicity of hg in turtles. total hg (thg) concentrations in blood were determined for 552 turtles representing four different species (chelydra serpentina, sternotherus odoratus, chrysemys picta, and pseudemys rubriventris) from a hg-contaminated site on the south river (va, usa) and upstream refe ... | 2007 | 17702349 |
| 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 |
| high incidence of deformity in aquatic turtles in the john heinz national wildlife refuge. | the john heinz national wildlife refuge is subject to pollution from multiple sources. we studied development of snapping turtle (chelydra serpentina) and painted turtle (chrysemys picta) embryos from the refuge from 2000 through 2003. mean annual deformity rate of pooled painted turtle clutches over four years ranged from 45 to 71%, while that of snapping turtle clutches ranged from 13 to 19%. lethal deformities were more common than minor or moderate deformities in embryos of both species. adu ... | 2006 | 16360253 |
| 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 |
| observations on the leech placobdella ornata feeding from bony tissues of turtles. | the leech placobdella ornata was observed feeding from the blood sinuses of the plastron and carapace bones of chelydra serpentina and chrysemys picta. evidence of successful feeding included blood upwelling from the point of attachment and gastric ceca of the leeches freshly filled with blood after removal. there was an apparent preference for the sulci between scales of the shell. | 2004 | 15562628 |
| 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 |
| effect of graded hypoxic and acidotic stress on contractile force of heart muscle from hypoxia-tolerant and hypoxia-intolerant turtles. | previous studies have shown that isometric contractile force of in vitro cardiac muscle from the anoxia-tolerant painted turtle, chrysemys picta bellii, decreases when anoxic and when acidotic. this study sought to define the thresholds for these responses in the isolated ventricular strips of the painted turtle and in the anoxia-intolerant softshell turtles, apalone spinifera. the ventricular strips were exposed to hco3- ringer's solution equilibrated at p(o2) 156, 74, 37, 19, and 0 mmhg (45 mi ... | 2005 | 15828014 |
| lactic acid buffering by bone and shell in anoxic softshell and painted turtles. | we tested two hypotheses: first, that the inferior anoxia tolerance of the softshell turtle, apalone spinifera, compared to the western painted turtle, chrysemys picta bellii, is related to its less mineralized shell, and second, that turtle bone, like its shell, stores lactate during prolonged anoxia. lactate concentrations of blood, hindlimb bone, and shell were measured on normoxic apalone and chrysemys and after anoxic submergence at 10 degrees c for 2 and 9 d, respectively. blood and shell ... | 2016 | 10893168 |
| organization of nucleus rotundus, a tectofugal thalamic nucleus in turtles. ii. ultrastructural analyses. | nucleus rotundus in a large, tectorecipient nucleus in the dorsal thalamus of the pond turtles pseudemys scripta and chrysemys picta. rotundal neurons form a single, morphologically homogeneous population (rainey, '79) that projects to the dorsal ventricular ridge in the telencephalon. the present paper examines the morphology of and the distribution of synapses upon rotundal neurons. astrocytes, oligodendrocytes, and neurons can be identified in both 1-micrometer sections stained with toluidine ... | 1982 | 7130452 |
| osteology and skeletal development of apalone spinifera (reptilia: testudines: trionychidae). | despite considerable attention that other groups of reptiles have received, few descriptions of the development and sequences of chondrification and ossification of the entire skeleton of turtles exist. herein, the adult skeleton of the spiny softshell turtle, apalone spinifera (testudines: trionychidae), is described; this description forms a basis of comparison for the embryonic skeleton and its ontogenesis. descriptions are made on the basis of cleared and double-stained embryos and dry skele ... | 2003 | 12616574 |
| hypoxia tolerance, nitric oxide, and nitrite: lessons from extreme animals. | among vertebrates able to tolerate periods of oxygen deprivation, the painted and red-eared slider turtles (chrysemys picta and trachemys scripta) and the crucian carp (carassius carassius) are the most extreme and can survive even months of total lack of oxygen during winter. the key to hypoxia survival resides in concerted physiological responses, including strong metabolic depression, protection against oxidative damage and-in air-breathing animals-redistribution of blood flow. each of these ... | 2015 | 25729057 |
| seasonal changes in physiology and development of cold hardiness in the hatchling painted turtle chrysemys picta. | hatchling painted turtles (chrysemys picta) commonly hibernate in shallow, natal nests where winter temperatures may fall below -10 degrees c. although hatchlings are moderately freeze-tolerant, they apparently rely on supercooling to survive exposure to severe cold. we investigated seasonal changes in physiology and in the development of supercooling capacity and resistance to inoculative freezing in hatchling chrysemys picta exposed in the laboratory to temperatures that decreased from 22 to 4 ... | 2000 | 11044384 |
| 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 |
| genetic effects of landscape, habitat preference and demography on three co-occurring turtle species. | expanding the scope of landscape genetics beyond the level of single species can help to reveal how species traits influence responses to environmental change. multispecies studies are particularly valuable in highly threatened taxa, such as turtles, in which the impacts of anthropogenic change are strongly influenced by interspecific differences in life history strategies, habitat preferences and mobility. we sampled approximately 1500 individuals of three co-occurring turtle species across a g ... | 2017 | 27997082 |
| using pharmacological manipulation and high-precision radio telemetry to study the spatial cognition in free-ranging animals. | an animal's ability to perceive and learn about its environment plays a key role in many behavioral processes, including navigation, migration, dispersal and foraging. however, the understanding of the role of cognition in the development of navigation strategies and the mechanisms underlying these strategies is limited by the methodological difficulties involved in monitoring, manipulating the cognition of, and tracking wild animals. this study describes a protocol for addressing the role of co ... | 2016 | 27842346 |
| the metabolic consequences of repeated anoxic stress in the western painted turtle, chrysemys picta bellii. | the painted turtle is known for its extreme tolerance to anoxia, but it is unknown whether previous experience with anoxic stress might alter physiological performance during or following a test bout of anoxia. repeatedly subjecting 25°c-acclimated painted turtles to 2h of anoxic stress every other day for 19days (10 submergence bouts total) caused resting levels of liver glycogen to decrease by 17% and liver citrate synthase (cs) and cytochrome oxidase (cox) activities to increase by 33% and 11 ... | 2017 | 27474083 |
| effects of developmental exposure to bisphenol a and ethinyl estradiol on spatial navigational learning and memory in painted turtles (chrysemys picta). | developmental exposure of turtles and other reptiles to endocrine disrupting chemicals (edcs), including bisphenol a (bpa) and ethinyl estradiol (ee2, estrogen present in birth control pills), can induce partial to full gonadal sex-reversal in males. no prior studies have considered whether in ovo exposure to edcs disrupts normal brain sexual differentiation. yet, rodent model studies indicate early exposure to these chemicals disturbs sexually selected behavioral traits, including spatial navig ... | 2016 | 27476434 |
| stress hormone levels in a freshwater turtle from sites differing in human activity. | glucocorticoids, such as corticosterone (cort), commonly serve as a measure of stress levels in vertebrate populations. these hormones have been implicated in regulation of feeding behaviour, locomotor activity, body mass, lipid metabolism and other crucial behaviours and physiological processes. thus, understanding how glucocorticoids fluctuate seasonally and in response to specific stressors can yield insight into organismal health and the overall health of populations. i compared circulating ... | 2016 | 27293763 |
| phosphorylation of the mitochondrial atp-sensitive potassium channel occurs independently of pkcε in turtle brain. | neurons from the western painted turtle (chrysemys picta bellii) are remarkably resilient to anoxia. this is partly due to a reduction in the permeability of excitatory glutamatergic ion channels, initiated by mitochondrial atp-sensitive k(+) (mk(+)atp) channel activation. the aim of this study was to determine if: 1) pkcε, a kinase associated with hypoxic stress tolerance, is more highly expressed in turtle brain than the anoxia-intolerant rat brain; 2) pkcε translocates to the mitochondrial me ... | 2016 | 27280321 |
| decades of field data reveal that turtles senesce in the wild. | lifespan and aging rates vary considerably across taxa; thus, understanding the factors that lead to this variation is a primary goal in biology and has ramifications for understanding constraints and flexibility in human aging. theory predicts that senescence-declining reproduction and increasing mortality with advancing age-evolves when selection against harmful mutations is weaker at old ages relative to young ages or when selection favors pleiotropic alleles with beneficial effects early in ... | 2016 | 27140634 |
| effects of low-oxygen conditions on embryo growth in the painted turtle, chrysemys picta. | low-oxygen conditions (hypoxia; <21% o2 ) are considered unfavorable for growth; yet, embryos of many vertebrate taxa develop successfully in hypoxic subterranean environments. although enhanced tolerance to hypoxia has been demonstrated in adult reptiles, such as in the painted turtle (chrysemys picta), its effects on sensitive embryo life stages warrant attention. we tested the hypothesis that short-term hypoxia negatively affects growth during day 40 of development in c. picta, when o2 demand ... | 2017 | 27135638 |
| turtles outsmart rapid environmental change: the role of cognition in navigation. | animals inhabiting changing environments show high levels of cognitive plasticity. cognition may be a means by which animals buffer the impact of environmental change. however, studies examining the evolution of cognition seldom compare populations where change is rapid and selection pressures are strong. we investigated this phenomenon by radiotracking experienced and naïve eastern painted turtles (chrysemys picta) as they sought new habitats when their pond was drained. resident adults repeate ... | 2017 | 27065017 |
| pharmacological evidence is consistent with a prominent role of spatial memory in complex navigation. | the ability to learn about the spatial environment plays an important role in navigation, migration, dispersal, and foraging. however, our understanding of both the role of cognition in the development of navigation strategies and the mechanisms underlying these strategies is limited. we tested the hypothesis that complex navigation is facilitated by spatial memory in a population of chrysemys picta that navigate with extreme precision (±3.5 m) using specific routes that must be learned prior to ... | 2016 | 26865305 |
| lactate accumulation, glycogen depletion, and shell composition of hatchling turtles during simulated aquatic hibernation. | we submerged hatchling western painted turtles chrysemys picta schneider, snapping turtles chelydra serpentina l. and map turtles graptemys geographica le sueur in normoxic and anoxic water at 3 degrees c. periodically, turtles were removed and whole-body [lactate] and [glycogen] were measured along with relative shell mass, shell water, and shell ash. we analyzed the shell for [na+], [k+], total calcium, total magnesium, pi and total co2. all three species were able to tolerate long-term submer ... | 2004 | 15235017 |
| 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 |
| yolk hormone levels in the eggs of snapping turtles and painted turtles. | although yolk steroids appear to play important roles in the development, growth, and behavior of some birds, their effects in oviparous reptiles are largely unknown. these investigations were initiated to determine initial levels of steroid hormones in the yolks of eggs from two turtle species. clutches of snapping turtle (chelydra serpentina) and of painted turtle (chrysemys picta) eggs were collected and individual egg yolks were analyzed for estradiol-17beta (e(2)) and testosterone (t) using ... | 2002 | 12161198 |
| transmission of haemogregarina balli from painted turtles to snapping turtles through the leech placobdella ornata. | six leeches (placobdella ornata) were allowed to feed on a painted turtle (chrysemys picta marginata) infected with haemogregarina balli and subjected to a period of diapause before being allowed to feed on 2 laboratory-reared snapping turtles (chelydra serpentina). weekly examination of thin blood films revealed infections of the turtles at 130 days postfeeding. these observations provide support for broad host specificity of hemogregarine parasites of chelonians. | 2001 | 11695407 |
| 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 |
| discovery of the youngest sex chromosomes reveals first case of convergent co-option of ancestral autosomes in turtles. | most turtle species possess temperature-dependent sex determination (tsd), but genotypic sex determination (gsd) has evolved multiple times independently from the tsd ancestral condition. gsd in animals typically involves sex chromosomes, yet the sex chromosome system of only 9 out of 18 known gsd turtles has been characterized. here, we combine comparative genome hybridization (cgh) and bac clone fluorescent in situ hybridization (bac fish) to identify a macro-chromosome xx/xy system in the gsd ... | 2017 | 26842819 |