| heterogeneous bioapatite carbonation in western painted turtles is unchanged after anoxia. | adsorbed and structurally incorporated carbonate in bioapatite, the primary mineral phase of bone, is observed across vertebrates, typically at 2-8 wt%, and supports critical physiological and biochemical functions. several turtle species contain elevated bone-associated carbonate, a property linked to ph buffering and overwintering survival. prior studies of turtle bone utilized bulk analyses, which do not provide spatial resolution of carbonate. using raman spectroscopy, the goals of this stud ... | 2019 | 30930203 |
| geographic variation in thermal sensitivity of early life traits in a widespread reptile. | taxa with large geographic distributions generally encompass diverse macroclimatic conditions, potentially requiring local adaptation and/or phenotypic plasticity to match their phenotypes to differing environments. these eco-evolutionary processes are of particular interest in organisms with traits that are directly affected by temperature, such as embryonic development in oviparous ectotherms. here we examine the spatial distribution of fitness-related early life phenotypes across the range of ... | 2019 | 30891217 |
| extreme thermal fluctuations from climate change unexpectedly accelerate demographic collapse of vertebrates with temperature-dependent sex determination. | global climate is warming rapidly, threatening vertebrates with temperature-dependent sex determination (tsd) by disrupting sex ratios and other traits. less understood are the effects of increased thermal fluctuations predicted to accompany climate change. greater fluctuations could accelerate feminization of species that produce females under warmer conditions (further endangering tsd animals), or counter it (reducing extinction risk). here we use novel experiments exposing eggs of painted tur ... | 2019 | 30862793 |
| detecting coevolution of positively selected in turtles sperm-egg fusion proteins. | physically interacting sperm-egg proteins have been identified using gene-modified animals in some mammal species. three proteins are essential for sperm-egg binding: izumo1 on the sperm surface, and juno and cd9 on the egg surface. most proteins linked to reproductive function evolve rapidly among species by positive selection, and have correlated evolutionary rates to compensate for changes on both the sperm and egg. up to now, interactions between sperm and egg proteins have not been identifi ... | 2019 | 30790628 |
| the effect of dietary carotenoid increase on painted turtle spot and stripe color. | determination of how carotenoid-based color patches change with pigmentary access is important to understanding color patch function in animals. we performed a carotenoid addition experiment on male painted turtles (chrysemys picta) to determine if an increase in dietary carotenoids led to location-specific changes in painted turtle spot and stripe color. turtles fed large quantities of carotenoids had increased yellow chroma in chin stripes and increased red chroma in the neck and carapace stri ... | 2019 | 30557612 |
| of molecules, memories and migration: m1 acetylcholine receptors facilitate spatial memory formation and recall during migratory navigation. | many animals use complex cognitive processes, including the formation and recall of memories, for successful navigation. however, the developmental and neurological processes underlying these cognitive aspects of navigation are poorly understood. to address the importance of the formation and recollection of memories during navigation, we pharmacologically manipulated turtles (chrysemys picta) that navigate long distances using precise, complex paths learned during a juvenile critical period. we ... | 2018 | 30429306 |
| taurine activates glycine and gabaa receptor currents in anoxia-tolerant painted turtle pyramidal neurons. | unlike anoxia-intolerant mammals, painted turtles can survive extended periods without oxygen. this is partly accomplished by an anoxia-mediated increase in gamma-aminobutyric acid (gaba) release, which activates gaba receptors and mediates spike arrest in turtle neurons via shunting inhibition. extracellular taurine levels also increase during anoxia; why this occurs is unknown but it is speculated that glycine and/or gabaa/b receptors are involved. given the general importance of inhibitory ne ... | 2018 | 30237241 |
| environmentally induced phenotypic plasticity explains hatching synchrony in the freshwater turtle chrysemys picta. | environmentally cued hatching allows embryos to alter the time of hatching in relation to environment through phenotypic plasticity. spatially variable temperatures within shallow nests of many freshwater turtles cause asynchronous development of embryos within clutches, yet neonates still hatch synchronously either by hatching early or via metabolic compensation. metabolic compensation and changes in circadian rhythms presumably enable embryos to adjust their developmental rates to catch up to ... | 2018 | 30192440 |
| the role of acetylcholine in attention in turtles (chrysemys picta). | research on mammals and turtles has suggested that acetylcholine is involved in attention in these groups. two experiments investigated the ability of painted turtles (chrysemys picta) to ignore irrelevant stimuli when the basal forebrain acetylcholine system was compromised. in experiment 1, turtles given lesions of the basal magnocellular cholinergic nucleus (nbm) or sham lesions were tested on a go/no go discrimination between horizontal and vertical stripes with or without irrelevant inserts ... | 2018 | 30176658 |
| disentangling the genetic effects of refugial isolation and range expansion in a trans-continentally distributed species. | in wide-ranging taxa with historically dynamic ranges, past allopatric isolation and range expansion can both influence the current structure of genetic diversity. considering alternate historical scenarios involving expansion from either a single refugium or from multiple refugia can be useful in differentiating the effects of isolation and expansion. here, we examined patterns of genetic variability in the trans-continentally distributed painted turtle (chrysemys picta). we utilized an existin ... | 2019 | 30171190 |
| changes in the material properties of the shell during simulated aquatic hibernation in the anoxia-tolerant painted turtle. | western painted turtles (chrysemys picta bellii) tolerate anoxic submergence longer than any other tetrapod, surviving more than 170 days at 3°c. this ability is due, in part, to the shell and skeleton simultaneously releasing calcium and magnesium carbonates, and sequestering lactate and h+ to prevent lethal decreases in body fluid ph. we evaluated the effects of anoxic submergence at 3°c on various material properties of painted turtle bone after 60, 130 and 167-170 days, and compared them wit ... | 2018 | 30065038 |
| effects of urbanization on the population structure of freshwater turtles across the united states. | landscape-scale alterations that accompany urbanization may negatively affect the population structure of wildlife species such as freshwater turtles. changes to nesting sites and higher mortality rates due to vehicular collisions and increased predator populations may particularly affect immature turtles and mature female turtles. we hypothesized that the proportions of adult female and immature turtles in a population will negatively correlate with landscape urbanization. as a collaborative ef ... | 2018 | 29781169 |
| the effect of hormone manipulations on sex ratios varies with environmental conditions in a turtle with temperature-dependent sex determination. | exogenous application of steroids and related substances to eggs affects offspring sex ratios in species with temperature-dependent sex determination (tsd). laboratory studies demonstrate that this effect is most pronounced near the constant temperature that produces 1:1 sex ratios (i.e., pivotal temperature). however, the impact of such chemicals on sex determination under natural nest temperatures (which fluctuate daily) is unknown, but could provide insight into the relative contributions of ... | 2017 | 29356364 |
| sex-specific growth, shape, and their impacts on the life history of a long-lived vertebrate. | individual growth rates both comprise and determine life-history phenotypes. despite decades of interest in understanding the relationship between individual growth and life history, chelonian longevity has limited our ability to robustly estimate individual growth curves that span the life of both sexes. | 2018 | 32944008 |
| effects of augmented corticosterone in painted turtle eggs on offspring development and behavior. | maternal stressors can play an integral role in offspring development and ultimate behaviors in many vertebrates. increased circulating stress avoidance hormones can be reflected in elevated concentrations in ova, thus providing a potential mechanism for maternal stress to be transmitted to offspring even in taxa without parental care. in this study, we assessed the potential impacts of augmented stress avoidance hormones on offspring development and anti-predator behaviors in a freshwater turtl ... | 2018 | 29031544 |
| the effects of ph and pi on tension and ca2+ sensitivity of ventricular myofilaments from the anoxia-tolerant painted turtle. | we aimed to determine how increases in intracellular h+ and inorganic phosphate (pi) to levels observed during anoxic submergence affect contractility in ventricular muscle of the anoxia-tolerant western painted turtle, chrysemys picta bellii skinned multicellular preparations were exposed to six treatments with physiologically relevant levels of ph (7.4, 7.0, 6.6) and pi (3 and 8 mmol l-1). each preparation was tested in a range of calcium concentrations (pca 9.0-4.5) to determine the pca-tensi ... | 2017 | 28939564 |
| corrigendum to "effects of developmental exposure to bisphenol a and ethinyl estradiol on spatial navigational learning and memory in painted turtles (chrysemys picta)" [horm. behav. 85 (2016) 48-55]. | | 2017 | 28551168 |
| medip-seq and ncpg analyses illuminate sexually dimorphic methylation of gonadal development genes with high historic methylation in turtle hatchlings with temperature-dependent sex determination. | dna methylation alters gene expression but not dna sequence and mediates some cases of phenotypic plasticity. temperature-dependent sex determination (tsd) epitomizes phenotypic plasticity where environmental temperature drives embryonic sexual fate, as occurs commonly in turtles. importantly, the temperature-specific transcription of two genes underlying gonadal differentiation is known to be induced by differential methylation in tsd fish, turtle and alligator. yet, how extensive is the link b ... | 2017 | 28533820 |
| corrigendum to "developmental exposure to bisphenol a (bpa) alters sexual differentiation in painted turtles (chrysemys picta)" [gen. comp. endocr. 216 (2015) 77-85]. | | 2017 | 28454885 |
| daily thermal fluctuations to a range of subzero temperatures enhance cold hardiness of winter-acclimated turtles. | although seasonal increases in cold hardiness are well documented for temperate and polar ectotherms, relatively little is known about supplemental increases in cold hardiness during winter. because many animals are exposed to considerable thermal variation in winter, they may benefit from a quick enhancement of cold tolerance prior to extreme low temperature. hatchling painted turtles (chrysemys picta) overwintering in their natal nests experience substantial thermal variation in winter, and re ... | 2017 | 28409226 |
| assessment of anoxia tolerance and photoperiod dependence of gabaergic polarity in the pond snail lymnaea stagnalis. | the pond snail lymnaea stagnalis is reported to be anoxia-tolerant and if the tolerance mechanism is similar to that of the anoxia-tolerant painted turtle, gaba should play an important role. a potentially confounding factor investigating the role of gaba in anoxia tolerance are reports that gaba has both inhibitory and excitatory effects within l. stagnalis central ganglion. we therefore set out to determine if seasonality or photoperiod has an impact on: 1) the anoxia-tolerance of the intact p ... | 2017 | 27664385 |
| transcriptomic responses of the heart and brain to anoxia in the western painted turtle. | painted turtles are the most anoxia-tolerant tetrapods known, capable of surviving without oxygen for more than four months at 3°c and 30 hours at 20°c. to investigate the transcriptomic basis of this ability, we used rna-seq to quantify mrna expression in the painted turtle ventricle and telencephalon after 24 hours of anoxia at 19°c. reads were obtained from 22,174 different genes, 13,236 of which were compared statistically between treatments for each tissue. total tissue rna contents decreas ... | 2015 | 26147940 |
| scavenging ros dramatically increase nmda receptor whole-cell currents in painted turtle cortical neurons. | oxygen deprivation triggers excitotoxic cell death in mammal neurons through excessive calcium loading via over-activation of n-methyl-d-aspartate (nmda) and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (ampa) receptors. this does not occur in the western painted turtle, which overwinters for months without oxygen. neurological damage is avoided through anoxia-mediated decreases in nmda and ampa receptor currents that are dependent upon a modest rise in intracellular ca(2+) concentra ... | 2014 | 25063855 |
| anoxia-mediated calcium release through the mitochondrial permeability transition pore silences nmda receptor currents in turtle neurons. | mammalian neurons are anoxia sensitive and rapidly undergo excitotoxic cell death when deprived of oxygen, mediated largely by ca(2+) entry through over-activation of n-methyl-d-aspartate receptors (nmdars). this does not occur in neurons of the anoxia-tolerant western painted turtle, where a decrease in nmdar currents is observed with anoxia. this decrease is dependent on a modest rise in cytosolic [ca(2+)] ([ca(2+)]c) that is mediated by release from the mitochondria. the aim of this study was ... | 2013 | 24259257 |
| taking the temperature of the painted turtle. | | 2013 | 23965557 |
| oxygen-sensitive reduction in ca²⁺-activated k⁺ channel open probability in turtle cerebrocortex. | in response to low ambient oxygen levels the western painted turtle brain undergoes a large depression in metabolic rate which includes a decrease in neuronal action potential frequency. this involves the arrest of n-methyl-d-aspartate receptor (nmdar) and α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor (ampar) currents and paradoxically an increase in γ-aminobutyric acid receptor (gabar) currents in turtle cortical neurons. in a search for other oxygen-sensitive channels we discov ... | 2013 | 23384611 |
| painted turtle cortex is resistant to an in vitro mimic of the ischemic mammalian penumbra. | anoxia or ischemia causes hyperexcitability and cell death in mammalian neurons. conversely, in painted turtle brain anoxia increases γ-amino butyric acid (gaba)ergic suppression of spontaneous electrical activity, and cell death is prevented. to examine ischemia tolerance in turtle neurons, we treated cortical sheets with an in vitro mimic of the penumbral region of stroke-afflicted mammalian brain (ischemic solution, is). we found that during is perfusion, neuronal membrane potential (v(m)) an ... | 2012 | 22805876 |
| regulation of ampa receptor currents by mitochondrial atp-sensitive k+ channels in anoxic turtle neurons. | mammalian neurons rapidly undergo excitotoxic cell death during anoxia, whereas neurons from the anoxia-tolerant painted turtle survive without oxygen for hours and offer a unique model to study mechanisms to reduce the severity of cerebral stroke. an anoxia-mediated decrease in whole cell n-methyl-d-aspartate receptor and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (ampar) currents are an important part of the turtle's natural defense. here we investigate the role of mitochond ... | 2010 | 20685922 |
| egg incubation and collection of painted turtle embryos. | this protocol describes how to incubate painted turtle eggs and collect embryos for gene expression analysis. the same basic protocol can be used to incubate eggs and collect embryos from other turtle species by modifying the incubation temperature to suit the particular developmental needs of each species. | 2009 | 20147203 |
| sex allocation based on relative and absolute condition. | traditional models predict that organisms should allocate to sex based on their condition relative to the condition of their competitors, tracking shifts in mean condition in fluctuating environments, and maintaining an equilibrium sex ratio. in contrast, when individuals are constrained to define their condition absolutely, environmental fluctuations induce fluctuating sex ratios and the evolutionary loss of condition-dependent sex allocation in short-lived organisms. here, we present a simulat ... | 2010 | 20002168 |
| delta-opioid receptor antagonism induces nmda receptor-dependent excitotoxicity in anoxic turtle cortex. | delta-opioid receptor (dor) activation is neuroprotective against short-term anoxic insults in the mammalian brain. this protection may be conferred by inhibition of n-methyl-d-aspartate receptors (nmdars), whose over-activation during anoxia otherwise leads to a deleterious accumulation of cytosolic calcium ([ca(2+)](c)), severe membrane potential (e(m)) depolarization and excitotoxic cell death (ecd). conversely, nmdar activity is decreased by approximately 50% with anoxia in the cortex of the ... | 2008 | 18931323 |
| mitochondrial atp-sensitive k+ channels regulate nmdar activity in the cortex of the anoxic western painted turtle. | hypoxic mammalian neurons undergo excitotoxic cell death, whereas painted turtle neurons survive prolonged anoxia without apparent injury. anoxic survival is possibly mediated by a decrease in n-methyl-d-aspartate receptor (nmdar) activity and maintenance of cellular calcium concentrations ([ca(2+)](c)) within a narrow range during anoxia. in mammalian ischaemic models, activation of mitochondrial atp-sensitive k(+) (mk(atp)) channels partially uncouples mitochondria resulting in a moderate incr ... | 2008 | 18079161 |
| ampa receptors undergo channel arrest in the anoxic turtle cortex. | without oxygen, all mammals suffer neuronal injury and excitotoxic cell death mediated by overactivation of the glutamatergic n-methyl-d-aspartate receptor (nmdar). the western painted turtle can survive anoxia for months, and downregulation of nmdar activity is thought to be neuroprotective during anoxia. nmdar activity is related to the activity of another glutamate receptor, the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor (ampar). ampar blockade is neuroprotective agains ... | 2008 | 18056983 |
| lactate metabolism in anoxic turtles: an integrative review. | painted turtles can accumulate lactic acid to extremely high concentrations during long-term anoxic submergence, with plasma lactate exceeding 200 mmol l(-1). the aims of this review are twofold: (1) to summarize aspects of lactate metabolism in anoxic turtles that have not been reviewed previously and (2) to identify gaps in our knowledge of turtle lactate metabolism by comparing it with lactate metabolism during and after exercise in other vertebrates. the topics reviewed include analyses of l ... | 2008 | 17940776 |
| anoxia-induced changes in reactive oxygen species and cyclic nucleotides in the painted turtle. | the western painted turtle survives months without oxygen. a key adaptation is a coordinated reduction of cellular atp production and utilization that may be signaled by changes in the concentrations of reactive oxygen species (ros) and cyclic nucleotides (camp and cgmp). little is known about the involvement of cyclic nucleotides in the turtle's metabolic arrest and ros have not been previously measured in any facultative anaerobes. the present study was designed to measure changes in these sec ... | 2007 | 17347830 |
| renal responses to mesotocin in western painted turtles compared with the antidiuretic response to arginine vasotocin. | we have examined the renal responses to the two neurohypophysial peptides mesotocin (mt) and arginine vasotocin (avt) in western painted turtles (chrysemis picta). ureteral urine was collected, after removal of the urinary bladder, to exclude modification by trans-bladder fluxes of ions and or water. test doses of mt ranged from 5 to 500 ng kg(-1) i.v. but only the uppermost pharmacological doses of 300 and 500 ng kg(-1) were followed by even a small reduction in gfr, a renal tubular antidiuresi ... | 2005 | 16165134 |
| calcium and protein phosphatase 1/2a attenuate n-methyl-d-aspartate receptor activity in the anoxic turtle cortex. | excitotoxic cell death (ecd) is characteristic of mammalian brain following min of anoxia, but is not observed in the western painted turtle following days to months without oxygen. a key event in ecd is a massive increase in intracellular ca(2+) by over-stimulation of n-methyl-d-aspartate receptors (nmdars). the turtle's anoxia tolerance may involve the prevention of ecd by attenuating nmdar-induced ca(2+) influx. the goal of this study was to determine if protein phosphatases (pps) and intrace ... | 2005 | 16139540 |
| effects of swimming on metabolic recovery from anoxia in the painted turtle. | anoxic submergence in the western painted turtle results in a severe metabolic acidosis characterized by high plasma lactate and depressed arterial ph, a response similar to that seen in other vertebrates following exhaustive exercise. we tested the hypothesis that 1 or 2 h of aerobic swimming following anoxic submergence would enhance the rate of lactate disappearance from the blood just as sustained aerobic exercise does in mammals and fishes following strenuous exercise. following 2 h of anox ... | 2004 | 15201303 |
| effect of anoxia and pharmacological anoxia on whole-cell nmda receptor currents in cortical neurons from the western painted turtle. | the mammalian brain undergoes rapid cell death during anoxia that is characterized by uncontrolled ca(2+) entry via n-methyl-d-aspartate receptors (nmdars). in contrast, the western painted turtle is extremely anoxia tolerant and maintains close-to-normal [ca(2+)](i) during periods of anoxia lasting from days to months. a plausible mechanism of anoxic survival in turtle neurons is the regulation of nmdars to prevent excitotoxic ca(2+) injury. however, studies using metabolic inhibitors such as c ... | 2016 | 12695985 |
| gap junctions do not underlie changes in whole-cell conductance in anoxic turtle brain. | an acute reduction in cell membrane permeability could provide an effective strategy to prolong anoxic survival. a previous study has shown that in the western painted turtle whole-cell neuronal conductance (g(w)) decreases during anoxia, which may be mediated by the activation of adenosine a(1) receptors and calcium. reduction in g(w) is thought to be the result of ion channel closure, but closure of gap junctions could also be responsible for this phenomenon. in our study, antibody staining of ... | 2003 | 12507621 |
| annual differences in female reproductive success affect spatial and cohort-specific genotypic heterogeneity in painted turtles. | long-term ecological data were used to evaluate the relative importance of movements, breeding structure, and reproductive ecological factors to the degree of spatial and age-specific variation in genetic characteristics of painted turtles (chrysemys picta) on the e. s. george reserve in southeastern michigan. estimates of the degree of spatial genetic structuring were based on the proportion of total genotypic variance partitioned within and between subpopulations (inferred from hierarchical f- ... | 1993 | 28564898 |
| seasonal variations in oviductal morphology of the painted turtle, chrysemys picta. | histology of each of the five segments of the oviduct of the female turtle chrysemys picta was described for successive intervals throughout their annual cycle. uterine and glandular segments showed marked seasonal variations in the extent and content of the submucosal and epithelial glands. submucosal glands were most prominent in preovulatory and postovulatory animals (may to june), regressing in late summer (oviposited animals) and recrudescing the following spring. these changes correlated w ... | 1991 | 29865522 |
| egg binding in a western painted turtle. | | 1979 | 17422058 |
| ultrastructure of the parathyroid gland of fresh-water turtles. | the parathyroid glands of fresh-water turtles (pseudemys scripta and chrysemys picta) are composed of cords of cells in which dark and light variants of chief cells and occasional oxyphil cells can be distinguished. cytoplasmic granules measuring about 0.3-0.4 μm and all the cellular organelles associated with protein and carbohydrate synthesis can be seen in both dark and light chief cells; the cytoplasm of oxyphils is packed with mitochondria which obscure other organelles. an unusual feature ... | 1972 | 30366482 |
| size and shape variation in the painted turtle. a principal component analysis. | | 1960 | 13790416 |