| tissue-specific expression of inducible and constitutive hsp70 isoforms in the western painted turtle. | expression of hsp73 and hsp72 in four tissues of the naturally anoxia-tolerant western painted turtle (chrysemys picta) was investigated in response to a 24 h forced dive and following 1 h recovery. of the tissues examined, brain and liver displayed approximately threefold and sevenfold higher basal hsp73 expression than heart and skeletal muscle. basal hsp72 expression was relatively low in all tissues examined. after the 24 h forced dive and 1 h recovery, hsp73 expression did not differ signif ... | 2003 | 12477900 |
| environmental sex determination in a reptile varies seasonally and with yolk hormones. | most hypotheses that have been put forward in order to explain the persistence of environmental sex determination (esd) in reptiles assume a relatively fixed association of sex with temperature-induced phenotype and no maternal influence on offspring sex. here we demonstrate the association of maternally derived yolk hormone levels with the offspring sex ratio and describe two new aspects of temperature-dependent sex determination (tsd), i.e. seasonal variation in both thermal response and yolk ... | 2000 | 12233772 |
| progesterone and progesterone receptors in reptiles. | the role of progesterone (p) has been most extensively studied in the female reproductive tissues (ovary, reproductive tract, mammary gland) and in the brain, in which it is an important regulator and modulator in conjunction with estradiol (e). in nonmammalian vertebrate species, less work has been done on p metabolites involved in ovulation. in addition, p induces the expression of egg-white proteins, decreases myometrial contractility, and facilitates processing of eggs, formation of eggshell ... | 2002 | 12161195 |
| maternally derived yolk hormones vary in follicles of the painted turtle, chrysemys picta. | the transfer of hormones from a female to her offspring is known to occur in egg laying vertebrates, and the potential for these early, maternally derived hormones to influence sex determination in reptiles with temperature-dependent sex determination is intriguing. in the present study, we examine variation in the concentrations of progesterone, testosterone, and estradiol among three follicle size classes within a female painted turtle (chrysemys picta) and among females across four periods th ... | 2002 | 12115920 |
| complete suppression of protein synthesis during anoxia with no post-anoxia protein synthesis debt in the red-eared slider turtle trachemys scripta elegans. | two previous studies of the effects of anoxia on protein synthesis in anoxia-tolerant turtles (trachemys scripta elegans, chrysemys picta bellii) have generated opposing results. using the flooding-dose method, we measured the rate of protein synthesis following injection and incorporation of a large dose of radiolabelled phenylalanine to resolve the question of whether anoxia results in a downregulation of protein synthesis. after 1 h of anoxia, levels of protein-incorporated radiolabel indicat ... | 2001 | 11815659 |
| sperm storage in turtles: a male perspective. | the storage and behavior of sperm collected from the epididymis of two emyiid turtles were examined. in chrysemys picta, the weight of the epididymis does not change significantly throughout the year as does the testis. however, in this species, as well as in trachemys scripta, the epididymis contains sperm throughout the entire year. sperm from both species have a relatively low motility and velocity of movement. in c. picta, equally low motilities are observed both in the autumn, shortly after ... | 2002 | 11754033 |
| cadmium: tissue distribution and binding protein induction in the painted turtle, chrysemys picta. | the freshwater painted turtle, chrysemys picta, was used to investigate (a) the distribution of an injected dose of 109cd in tissues over a period of 192 h (8 days) and (b) the effect of non-isotopic cadmium injection on tissue metal-binding protein levels. cadmium is cleared from the blood with 9% remaining in the circulation at 192 h. 109cd is found in all tissues, but is accumulated preferentially in liver, kidney, pancreas, and gastrointestinal tract. the liver is the primary site of cd accu ... | 2001 | 11544142 |
| seasonal variation in plasma lipids, lipoproteins, apolipoprotein a-i and vitellogenin in the freshwater turtle, chrysemys picta. | an analysis of plasma lipids and lipoprotein fractions was performed over the course of the annual ovarian cycle of the female turtle, chrysemys picta. determinations of total plasma triglycerides, cholesterol, vitellogenin and apolipoprotein a-i (apoa-i) were made. the lipid and protein composition of the lipoprotein fractions [very low density lipoprotein (vldl), low density lipoprotein (ldl), high density lipoprotein (hdl) and very high density lipoprotein (vhdl)] were also observed over the ... | 2001 | 11544071 |
| ultrastructural changes in granulosa cells and plasma steroid levels after administration of luteinizing hormone-releasing hormone in the western painted turtle, chrysemys picta. | in this study we investigated the effects of treatment by luteinizing hormone-releasing hormone (lhrh) on the morphology and steroid release of ovarian tissues in the western painted turtle, (chrysemys picta). in experiment i, four adult female turtles were injected with synthetic mammalian lhrh (i.p., 500 pg/g bodyweight) and four with saline 2-3 weeks prior to ovulation. granulosa cells from lhrh-treated turtles vs controls contained both preovulatory follicles (16-20 mm in diameter) and small ... | 2001 | 11521952 |
| genetic markers substantiate long-term storage and utilization of sperm by female painted turtles. | most studies of genetic parentage in natural populations have been limited to a single breeding season or reproductive episode and, thus, provide only a snapshot of individuals' mating behaviours. female turtles can store viable sperm in their reproductive tracts for as long as several years, but the extent to which this capacity is utilized in nature has remained unknown. here, we employ microsatellite markers to assess genetic paternity in successive clutches of individually marked, free-rangi ... | 2001 | 11488975 |
| effects of temperature and aquatic p(o2) on the physiology and behaviour of apalone ferox and chrysemys picta. | softshell turtles overwinter in the same bodies of water as some emydids, but their reduced shell and increased non-pulmonary gas exchange may contribute to a different mechanism of overwintering. the dynamics of bimodal respiration, diving behaviour and blood acid-base status in apalone ferox and chrysemys picta were investigated under two different temperatures combined with three different aquatic p(o2) levels. both species obtained oxygen through pulmonary and non-pulmonary routes. apalone f ... | 2001 | 11441060 |
| physiological responses to supercooling and hypoxia in the hatchling painted turtle, chrysemys picta. | we investigated physiological responses to supercooling in hatchling painted turtles (chrysemys picta) which remain in their natal nests over winter and therefore may become exposed to subzero temperatures. these turtles are freeze tolerant but also must rely on supercooling to survive exposure to the lower temperatures occurring in nests during winter. we compared whole-body concentrations of lactate, glucose, glycerol, and atp in turtles chilled at 0 degrees c, -4 degrees c, or -6 degrees c fo ... | 2001 | 11409631 |
| seasonal change in the capacity for supercooling by neonatal painted turtles. | hatchlings of the north american painted turtle (chrysemys picta) typically spend their first winter of life inside the shallow, subterranean nest where they completed incubation the preceding summer. this facet of their natural history commonly causes neonates in northerly populations to be exposed in mid-winter to ice and cold, which many animals survive by remaining unfrozen and supercooled. we measured the limit of supercooling in samples of turtles taken shortly after hatching and in other ... | 2001 | 11398756 |
| concentrations of steroid hormones in layers and biopsies of chelonian egg yolks. | the actions of circulating hormones, although relatively well understood for adults, are largely unknown for their developing embryos. transfer of maternal hormones to the egg is known to occur in oviparous species, and recently the presence of hormonally heterogeneous yolk layers has been described in two avian species. to investigate the possibility of a similar phenomenon occurring in chelonian species, egg yolk layers were analyzed in the painted turtle (chrysemys picta marginata) and the re ... | 2001 | 11161774 |
| the physiology of hibernation among painted turtles: the midland painted turtle (chrysemys picta marginata). | midland painted turtles from michigan were submerged at 3 degrees c in normoxic and anoxic water. in predive, and in turtles submerged for up to 150 days, plasma po2, pco2, ph, [cl-], [na+], [k+], total mg, total ca, lactate, glucose, and osmolality were measured; hematocrit and mass were determined, and plasma [hco3-] was calculated. anoxic turtles developed a severe metabolic acidosis, accumulating lactate from a predive value of 4.4 mmol/l to a 150-day value of 185 mmol/l, associated with a f ... | 2001 | 11084202 |
| the role of the integument as a barrier to penetration of ice into overwintering hatchlings of the painted turtle (chrysemys picta). | hatchlings of the north american painted turtle (chrysemys picta) spend their first winter of life inside a shallow, subterranean hibernaculum (the natal nest) where they may be exposed for extended periods to ice and cold. hatchlings seemingly survive exposure to such conditions by becoming supercooled (i.e., by remaining unfrozen at temperatures below the equilibrium freezing point for body fluids), so we investigated the role of their integument in preventing ice from penetrating into body co ... | 2000 | 11074582 |
| characteristics of nest soil, but not geographic origin, influence cold hardiness of hatchling painted turtles. | we investigated environmental factors influencing cold hardiness in hatchling painted turtles (chrysemys picta) indigenous to northeastern indiana and the sandhills of west-central nebraska. in both locations, hatchlings overwinter in their natal nests. survival of hatchlings chilled to minimum temperatures between -2.5 and -6.0 degrees c inside explanted natal nests ranged from 30 to 100%. mortality likely was caused by freezing of the turtles that was induced by contact with ice nuclei in the ... | 2001 | 11070346 |
| succinate and alanine as anaerobic end-products in the diving turtle (chrysemys picta bellii). | the western painted turtle is an extremely anoxia-tolerant vertebrate capable of tolerating blood lactate levels of 150-200 mm. since lactate increases to such high levels, other fermentation end-products such as succinate and alanine, which have not been previously measured in this species, might also be expected to increase. therefore, i measured turtle heart, liver, and blood concentrations of lactate, succinate, and alanine following a 28-day anoxic dive at 5 degrees c. succinate and lactate ... | 2000 | 11007183 |
| hepatic changes in the freeze-tolerant turtle chrysemys picta marginata in response to freezing and thawing. | select hepatic changes in the freeze-tolerant hatchling turtle, chrysemys picta marginata, were studied in response to freezing at -2.5 degrees c and thawing. upon freezing, a small, selective increase in the liver weight with no increase in body weight was seen suggestive of an hepatic capacitance response. in all turtles studies, lobular differences in the hepatic content of glycogen were evident: the smaller lobe contained twice as much glycogen as the larger lobe. the response to freezing an ... | 2000 | 10965355 |
| helminth parasites of the western painted turtle, chrysemys picta belli (gray), including neopolystoma elizabethae n. sp. (monogenea: polystomatidae), a parasite of the conjunctival sac. | neopolystoma elizabethae n. sp. is described from the conjunctival sac of the western painted turtle chrysemys picta belli (gray), from the upper peninsula of michigan. this is the first species found in this location from chelonians in north america. the new species differs from all other species of neopolystoma in possessing a circle of 8 genital spines that are recurved and possess a crescent-shaped base. eight additional species of helminths were found in the 5 turtles examined in this study ... | 2000 | 10958462 |
| chemical and thermal effects on the viability and motility of spermatozoa from the turtle epididymis. | the viability and motility of spermatozoa harvested from the epididymides of turtles were estimated to elucidate properties that might enable them to be stored over long periods of time. spermatozoa from the painted turtle, chrysemys picta, were analysed and compared with spermatozoa from two other turtles, trachemys scripta and sternotherus odoratus using the cellsoft analysis system for videotaped images. spermatozoa from c. picta and t. scripta, suspended in f-10 medium, showed low motility ( ... | 2000 | 10864839 |
| bone and shell contribution to lactic acid buffering of submerged turtles chrysemys picta bellii at 3 degrees c. | to evaluate shell and bone buffering of lactic acid during acidosis at 3 degrees c, turtles were submerged in anoxic or aerated water and tested at intervals for blood acid-base status and plasma ions and for bone and shell percent water, percent ash, and concentrations of lactate, ca(2+), mg(2+), p(i), na(+), and k(+). after 125 days, plasma lactate concentration rose from 1.6 +/- 0.2 mm (mean +/- se) to 155.2 +/- 10.8 mm in the anoxic group but only to 25.2 +/- 6.4 mm in the aerated group. the ... | 2000 | 10848524 |
| hypoxia-induced silencing of nmda receptors in turtle neurons. | hypoxia-induced suppression of nmda receptors (nmdars) in western painted turtle (chrysemys picta) cortical neurons may be critical for surviving months of anoxic dormancy. we report that nmdars are silenced by at least three different mechanisms operating at different times during anoxia. in pyramidal neurons from cerebrocortex, 1-8 min anoxia suppressed nmdar activity (ca(2+) influx and open probability) by 50-60%. this rapid decrease in receptor activity was controlled by activation of phosph ... | 2000 | 10804192 |
| living without oxygen: lessons from the freshwater turtle. | freshwater turtles, and specifically, painted turtles, chrysemys picta, are the most anoxia-tolerant air-breathing vertebrates. these animals can survive experimental anoxic submergences lasting up to 5 months at 3 degrees c. two general integrative adaptations underlie this remarkable capacity. first is a profound reduction in energy metabolism to approximately 10% of the normoxic rate at the same temperature. this is a coordinated reduction of both atp generating mechanisms and atp consuming p ... | 2000 | 10794959 |
| accumulation of lactate by supercooled hatchlings of the painted turtle (chrysemys picta): implications for overwinter survival. | hatchlings of the north american painted turtle (chrysemys picta) typically spend their first winter of life inside the shallow, subterranean nest where they completed embryogenesis the preceding summer. neonates at northern localities consequently may be exposed during winter to subzero temperatures and frozen soil. hatchlings apparently survive exposure to such conditions by supercooling, but the physiological consequences of this adaptive strategy have not been examined. we measured lactate i ... | 2000 | 10707324 |
| hepatic biotransformation enzymes in a sentinel species, the painted turtle (chrysemys picta), from cape cod, massachusetts: seasonal-, sex- and location related differences. | we report changes in biomarker enzymes (cytochrome p4501a, glutathione-s-transferase) and protein expression (cytochrome p4501a) in adult painted turtles, chrysemys picta, as part of a study of the potential impact of contaminants originating from the massachusetts military reservation on cape, cod, ma. in animals from both moody pond, a site potentially impacted by contaminants, and washburn pond, a nonimpacted site, rates of hepatic microsomal ethoxyresorufin-o. | 2000 | 23886024 |
| the physiology of diving in a north-temperate and three tropical turtle species. | we examined changes in blood gases, plasma ions, and acid-base status during prolonged submergence (6 h) of four aquatic turtle species in aerated water at 20 degrees c. our objective was to determine whether the temperate species, chrysemys picta bellii, exhibits greater tolerance to submergence apnea than the tropical species, pelomedusa subrufa, elseya novaeguineae, and emydura subglobosa. blood was sampled from indwelling arterial catheters for measurements of blood po2, pco2, ph, and hemato ... | 1999 | 10466218 |
| the physiology of hibernation among painted turtles: the eastern painted turtle chrysemys picta picta. | eastern painted turtles (chrysemys picta picta) from connecticut were submerged at 3 degrees c in normoxic and anoxic water to simulate potential respiratory environments within their hibernacula. those in normoxic water could survive submergence for at least 150 d, while those in anoxic water could survive for a maximum of about 125 d. turtles in normoxic water developed a slight metabolic acidosis as plasma lactate accumulated to about 50 mm in 150 d, while anoxic turtles developed a severe la ... | 2006 | 10438685 |
| the effect of isovolemic anaemia on blood o2 affinity and red cell triphosphate concentrations in the painted turtle (chrysemys picta). | the blood oxygen affinity of vertebrates is regulated, in part, through changes in red cell phosphate levels and increased oxygen affinity during reductions in inspired oxygen and is a well-described and common feature. however, during anaemia, when oxygen delivery is compromised by a reduction in blood oxygen carrying capacity, a lowering of blood oxygen affinity will facilitate oxygen unloading in the tissues, while oxygen loading at the gas exchange organ is not impaired. the present study in ... | 1999 | 10356763 |
| fatal trematodiasis in research turtles. | during a 5-year period, 16 freshwater turtles (trachemys scripta elegans and chrysemys picta) that were purchased for research purposes died spontaneously. clinical signs of disease included lethargy, constant swimming, swimming sideways, hemiplegia, and ulcerative lesions on the carapace. at necropsy, subcutaneous edema, hepatic necrosis, pancreatic necrosis, splenic necrosis, and intestinal parasites were identified. histologically, trematode eggs were seen within the liver, brain, spleen, kid ... | 1998 | 10090039 |
| soil hydric characteristics and environmental ice nuclei influence supercooling capacity of hatchling painted turtles chrysemys picta. | hatchling painted turtles (chrysemys picta) hibernate in their shallow natal nests where temperatures occasionally fall below -10 c during cold winters. because the thermal limit of freeze tolerance in this species is approximately -4 c, hatchlings rely on supercooling to survive exposure to extreme cold. we investigated the influence of environmental ice nuclei on susceptibility to inoculative freezing in hatchling c. picta indigenous to the sandhills of west-central nebraska. in the absence of ... | 1998 | 9787130 |
| hatchling painted turtles (chrysemys picta) survive only brief freezing of their bodily fluids. | neonatal painted turtles (chrysemys picta) spend their first winter inside the shallow, subterranean nest cavity where they completed embryogenesis. consequently, hatchlings at high latitudes may be exposed to ice and cold during the winter. this study was undertaken to determine how long hatchlings withstand freezing at temperatures slightly below 0 degree c because tolerance for freezing has been proposed to be the key to survival by overwintering animals. a thermocouple was glued to the carap ... | 1998 | 9787824 |
| reduction of nmda receptor activity in cerebrocortex of turtles (chrysemys picta) during 6 wk of anoxia. | survival of brain anoxia during months of winter dormancy by the western painted turtle, chrysemys picta, may rely on inactivation of neuronal ion channels. during 2 h of anoxia, ca2+ influx via the n-methyl-d-aspartate (nmda) subtype of glutamate receptor decreases 30-40%, but it is not known if prolonged anoxic dormancy is associated with even more profound downregulation of this important channel. because ionized ca2+ in cerebrospinal fluid (csf) increases five- to sixfold during prolonged an ... | 1998 | 9688964 |
| evidence for a photosensitive region in the caudal mesencephalon of the turtle brain. | using an in vitro brainstem-cerebellum preparation from the turtle chrysemys picta, burst discharge was recorded from the abducens nerve when light was directed on the brainstem. this burst discharge likely represents a neural correlate of the eye-blink reflex. increasing the intensity of the light stimulus reduced the response latency from a duration of many seconds to approximately 1-2 s. no response was recorded when the light source was covered. the response was present when infrared light w ... | 1998 | 9588779 |
| central trigeminal and posterior eighth nerve projections in the turtle chrysemys picta studied in vitro. | recent electrophysiological studies in the turtle chrysemys picta have suggested that a neural correlate of the eye-blink reflex can be evoked in an in vitro brain-stem-cerebellum preparation by electrical rather than natural stimulation of the cranial nerves. discharge recorded in the abducens nerve, which is similar to emg recordings from extraocular muscles during eye retraction, is triggered by a brief electrical stimulus applied to the ipsilateral trigeminal nerve. evidence also suggests th ... | 1998 | 9553692 |
| in vitro tolerance to anoxia and ischemia in isolated hearts from hypoxia sensitive and hypoxia tolerant turtles. | although freshwater turtles as a group are highly anoxia tolerant, dramatic interspecific differences in the degree of anoxia tolerance have been demonstrated in vivo. painted turtles (chrysemys picta bellii) appear to be the most hypoxia-tolerant species thus far studied, while softshelled turtles (trionyx spinifer) are the most hypoxia-sensitive. we have assumed that this dichotomy persists in vitro but have not, until now, directly tested this assumption. we therefore, directly compared the r ... | 1997 | 9505438 |
| 31p-nmr determinations of cytosolic phosphodiesters in turtle hearts. | as part of our ongoing research on cardiac hypoxia tolerance we have conducted 31p nuclear magnetic resonance (nmr) studies of isolated, perfused, working hearts from freshwater turtles, animals that are well known for their ability to tolerate prolonged periods of anoxia. a striking feature of turtle heart spectra is an extremely high concentration of nmr visible phosphodiesters (pdes). cardiac spectra from mammals, on the other hand, typically exhibit only a small resonance in the pde region. ... | 1997 | 9505428 |
| hypoxia, temperature, and ph/co2 effects on respiratory discharge from a turtle brain stem preparation. | an in vitro brain stem preparation from adult turtles (chrysemys picta) was used to examine the effects of anoxia and increased temperature and ph/co2 on respiration-related motor output. at ph approximately 7.45, hypoglossal (xii) nerve roots produced patterns of rhythmic bursts (peaks) of discharge (o.74 +/- 0.07 peaks/min 10.0 +/- 0.6 s duration) that were quantitatively similar to literature reports of respiratory activity in conscious, vagotomized turtles. respiratory discharge was stable f ... | 1998 | 9475877 |
| dorsal cortex lesions impair habituation in turtles (chrysemys picta). | two experiments investigated habituation in painted turtles (chrysemys picta). in the first, turtles were given lesions of the dorsal cortex or sham lesions and then trained on a restraint. although the sham-lesioned turtles learned to tolerate the restraint, the lesioned animals continued to struggle against it. thus dorsal cortex lesions disrupted habituation to restraint. in order to test habituation to a looming stimulus in a second experiment, all animals were habituated to the restraint be ... | 1998 | 9435970 |
| cold tolerance in hatchling painted turtles (chrysemys picta): supercooling or tolerance for freezing? | we studied tolerance for cold in hatchling painted turtles (chrysemys picta) from lake metigoshe, bottineau county, north dakota, to determine whether neonates in populations near the northern limit of distribution rely on a tolerance for freezing or on a capacity for supercooling to survive their first winter of life. we placed hatchlings individually into artificial hibernacula constructed in jars of damp, loamy sand and then cooled the jars to approximately -0.45 degrees c, which was below th ... | 2008 | 9361141 |
| effects of anoxia, acidosis and temperature on the contractile properties of turtle cardiac muscle strips. | the responses to anoxia and acidosis of cardiac ventricular muscle strips from the anoxia-tolerant turtle chrysemys picta bellii were investigated at 10 degrees c and 20 degrees c. force-velocity curves were determined by quick isotonic releases at 85% of the time to peak isometric force under control, anoxia, lactate acidosis and anoxic lactate acidosis conditions. the isotonic forces during quick releases spanned 5-95% of the measured isometric force at each conditions. superfusion solution ph ... | 1997 | 9246780 |
| effects of anoxia on intracellular free ca2+ in isolated cardiomyocytes from turtles. | one of the most important negative consequences of hypoxic stress in the mammalian myocardium is a breakdown in intracellular calcium homeostasis. this study examines the effects of anoxic stress on intracellular calcium regulation in isolated ventricular myocytes from a hypoxia tolerant vertebrate, the western painted turtle (chrysemys picta bellii). isolated calcium tolerant cardiomyocytes from turtle hearts were mounted on a glass cover slip that formed the bottom of a sealed, plexiglas perfu ... | 1997 | 9125683 |
| lactate accumulation in the shell of the turtle chrysemys picta bellii during anoxia at 3°c and 10°c | lactate concentrations were measured in the shell and plasma of the turtle chrysemys picta bellii after 3 months of submergence anoxia at 3°c and during and after 9 days of submergence anoxia at 10°c. liver and skeletal muscle lactate levels were also measured in control and anoxic animals at each temperature. at 3°c, mean shell lactate concentration (n=4) reached 133mmolkg-1shellmass and plasma lactate levels were 144mmoll-1; at 10°c, shell and plasma lactate concentrations (n=5 ... | 1997 | 9320212 |
| mechanisms of phi recovery from nh4cl-induced acidosis in anoxic isolated turtle heart: a 31p-nmr study. | mechanisms of intracellular ph (phi) recovery from nh4cl-induced acidosis were investigated on isolated perfused hearts of the turtle, chrysemys picta bellii, using 31p nuclear magnetic resonance (nmr) spectroscopy at 20 degrees c. a major goal was to assess the activity of these mechanisms under anoxic conditions. based on calculated buffer capacity and a phi recovery range at 20 degrees c of 6.75-6.95 (normal phi 7.2-7.4), mean h' efflux rate during perfusion with co2-free n-tris(hydroxymethyl ... | 1997 | 9038985 |
| anoxia-induced gene expression in turtle heart. upregulation of mitochondrial genes for nadh-ubiquinone oxidoreductase subunit 5 and cytochrome c oxidase subunit 1. | a cdna library constructed from heart of anoxia-exposed adult turtles (trachemys scripta elegans) was differentially screened with 32p-labeled single-stranded cdna probes from heart of control versus anoxic animals to clone genes induced by anoxia stress. four cdna clones, pbtar20, pbtar34, pbtar63 and pbtar914 were obtained and confirmed to be upregulated in response to anoxic submergence (20 h in n2-bubbled water at 7 degrees c). two clones, pbtar20 and pbtar63, were characterized by sequence ... | 1996 | 8898892 |
| lactate distribution and metabolism during and after anoxia in the turtle, chrysemys picta bellii. | to determine the fate of lactate during and after prolonged anoxia, 14c-labeled lactate was injected into turtles after 2 h of a 6-h submergence at 20 degrees c. 14c activities of plasma and chamber water were tested at intervals during anoxia and also in expired air during 39 h of recovery. partitioning of label in major body compartments [extracellular fluid (ecf), intracellular fluid (icf), and shell] and 14c activity and glycogen in selected tissues (heart, liver, and muscle) were measured a ... | 1996 | 8770142 |
| identification of central 5-ht and 5-ht1a receptors in the turtle brain (chrysemys picta). | radiologand binding studies were undertaken in the turtle whole brain, cerebellum and raphe using the selective radioligands [3h]5-hydroxytryptamine trifluoroacetate ([3h]5-ht) amd [3h]+/-8-hydroxy-2-(di-n-propylamino) tetralin hydrobromide ([3h]dpat) to identify serotonin (5-ht) receptors and the specific 5-ht1a receptor subtype. scatchard analysis identified a nanomolar affinity binding site for [3h]5-ht (12 nm) in turtle whole brain assays. a low affinity 5-ht1a site (102 nm) was also identif ... | 1996 | 8832643 |
| radioligand and immunochemical studies of turtle oviduct progesterone and estrogen receptors: correlations with hormone treatment and oviduct contractility. | progesterone (pr) and estrogen (er) receptors were previously identified and characterized in the reproductive tract of the turtle, chrysemys picta, and changes in pr levels were monitored during the seasonal cycle. to understand the hormonal regulation of pr, intact and ovariectomized animals were treated with estradiol, progesterone, and a combination of estradiol and progesterone, and high affinity pr and er levels were determined by radioligand binding studies. ovariectomy significantly decr ... | 1996 | 8713645 |
| anoxia and ischemia tolerance in turtle hearts. | it has been known since ancient times that turtle hearts exhibit extraordinary tolerance to anoxia or ischemia. the mechanisms by which they accomplish this remain obscure. the most important adaptation in anoxic turtles is a rapid and dramatic decrease in metabolic rate. nuclear magnetic resonance measurements indicate that painted turtle (chrysemys picta) hearts respond to anoxia with a rapid decrease in phosphocreatine (pcr; to 50% of control) after which pcr remains constant for at least 4 h ... | 2016 | 8728853 |
| reptilian (chrysemys picta) hepatic progesterone receptors: relationship to plasma steroids and the vitellogenic cycle. | in non-mammals, estrogen-induced yolk precursors produced by the adult female liver are the main nutritional source for development. evidence exists that progesterone exerts counter-regulatory effects on estrogen-induced vitellogenesis, and we have used the turtle model (chrysemys picta) to study changes in hepatic progesterone receptor during the vitellogenic cycle. using radioligand methods, we show that high and lower affinity binding sites are present in the cytosolic but not nuclear extract ... | 1995 | 7577726 |
| coccidia (apicomplexa: eimeriidae) from the big bend slider, trachemys gaigeae (testudines: emydidae), in new mexico. | twenty-nine big bend sliders trachemys gaigeae (hartweg, 1934) were collected from socorro county, new mexico, and their feces examined for coccidial parasites. three (10%) of the turtles were found to be infected with at least 1 coccidian. seven eimeria spp. (e. chrysemydis, e. graptemydos, e. marginata, e. pseudemydis, e. pseudogeographica, e. stylosa, and e. trachemydis) were harbored by t. gaigeae. all represent new host and distributional records for these previously described coccidians. i ... | 1995 | 7472884 |
| effects of input pressure on in vitro turtle heart during anoxia and acidosis: a 31p-nmr study. | in vitro working hearts of the turtle, chrysemys picta bellii, paced at 30 beats/min, were studied over a range of input pressures in the following sequence of perfusion conditions: control normoxia, control anoxia, lactacidotic normoxia, and lactacidotic anoxia. two such series of experiments were performed. in series 1 (n = 12), ventricular pressure (pv) and cardiac output were measured, and power output and dpv/dt were calculated. in series 2 (n = 5), intracellular phosphorus metabolites and ... | 1995 | 7900911 |
| the effect of prolonged anoxia at 3 degrees c on tissue high energy phosphates and phosphodiesters in turtles: a 31p-nmr study. | selected tissues (skeletal muscle, heart ventrical, and liver), sampled from turtles (chrysemys picta bellii) at 3 degrees c either under normoxic conditions or after 12 weeks of anoxic submergence were quantitatively analysed for intracellular ph and phosphorus metabolites using 31p-nmr. plasma was tested for osmolality and for the concentrations of lactate, calcium, and magnesium to confirm anoxic stress. we hypothesized that, in the anoxic animals, tissue atp levels would be maintained and th ... | 1995 | 7601958 |
| freeze tolerance in turtles: visual analysis by microscopy and magnetic resonance imaging. | two visual techniques were used to analyze the patterns of natural freezing and thawing in freeze-tolerant hatchling painted turtles chrysemys picta marginata. directional solidification plus light microscopy of liver, heart, and skeletal muscle slices was used to compare freezing at -4 degrees c (a survivable temperature in vivo) and -20 degrees c (not survivable). at -4 degrees c tissues showed large amounts of ice in expanded extracellular and vascular spaces, occupying 36% (liver) and 61% (m ... | 1994 | 7943419 |
| reproductive variation and the egg size-clutch size trade-off within and among populations of painted turtles (chrysemys picta bellii). | interpopulation variation in egg size, clutch size and clutch mass was studied 3 years in four populations of painted turtles (chrysemys picta bellii) from western nebraska. body size varied among all populations and was larger in two large (56-110 ha), sandhills lake populations than in two populations in smaller habitats (1.5-3.6 ha) of the platte river floodplain. reproductive parameters (egg mass, clutch mass, and clutch size) generally increased with maternal body size within populations. c ... | 1994 | 28313946 |
| climate change and temperature-dependent sex determination in reptiles. | despite increasing concern over the possible impact of global temperature change, there is little empirical evidence of direct temperature effects on biotic interactions in natural systems. clear assessment of the ecological and evolutionary impact of changing climatic temperature requires a natural system in which populations exhibit a direct unambiguous fitness response to thermal fluctuation. i monitored nests of a population of painted turtles (chrysemys picta) with temperature-dependent sex ... | 1994 | 8052608 |
| anatomical organization of the limb premotor network in the turtle (chrysemys picta) revealed by in vitro transport of biocytin and neurobiotin. | the in vitro turtle brainstem-cerebellum preparation has been a valuable tool in the study of central motor programs. in the present study, we investigate the anatomical organization of the turtle rubrocerebellar limb premotor network and its sensory connections in vitro by combining the rapid anterograde and retrograde transport of neurobiotin and biocytin with the extended viability of the isolated turtle brainstem-cerebellum. these compounds retrogradely labeled soma, dendrites, and axons, an ... | 1994 | 8063953 |
| lactic acidosis transiently increases metabolic rate of turtle myocytes. | we measured o2 consumption as an estimate of metabolic rate in isolated calcium-tolerant ventricular myocytes of turtles (chrysemys picta belli) at control ph 7.8 and in the same solution brought to ph 7.4 and 7.0 with additions of lactic acid. our aim was to test the hypothesis that lactic acidosis caused metabolic depression by initiating downregulation of na+ channels, and thus na(+)-k(+)-atpase (na+ pump) activity, which we would measure as a decrease in o2 consumption. myocyte o2 consumptio ... | 1994 | 8184967 |
| protein turnover during metabolic arrest in turtle hepatocytes: role and energy dependence of proteolysis. | hepatocytes from the western painted turtle (chrysemys picta bellii) are capable of a coordinated metabolic suppression of 88% during 10 h of anoxia at 25 degrees c. the energy dependence and role of proteolysis in this suppression were assessed in labile ([3h]phe-labeled) and stable ([14c]phe-labeled) protein pools. during anoxia, labile protein half-lives increased from 24.7 +/- 3.3 to 34.4 +/- 3.7 h, with stable protein half-lives increasing from 55.6 +/- 3.4 to 109.6 +/- 7.4 h. the total ano ... | 1994 | 8178951 |
| anoxic suppression of na(+)-k(+)-atpase and constant membrane potential in hepatocytes: support for channel arrest. | the maintenance of ion gradients across the plasma membrane by the na(+)-k(+)-atpase has been shown to utilize a large fraction of the total cellular energy demand. in view of the importance of ion gradients to cellular function, and the remarkable anoxia tolerance of chrysemys picta bellii (western painted turtle) and hepatocytes isolated from this species, it was of interest to determine if in response to anoxia 1) ion gradients were maintained and 2) if the activity of the plasma membrane na( ... | 1993 | 8238602 |
| microcalorimetric measurement of reversible metabolic suppression induced by anoxia in isolated hepatocytes. | the metabolic suppression due to anoxia in hepatocytes from the anoxia-tolerant turtle chrysemys picta bellii was measured directly using microcalorimetric techniques. the normoxic heat flux from hepatocytes in suspension (25 degrees c) was 1.08 +/- 0.08 mw/g cells and decreased by 76% to 0.26 +/- 0.03 mw/g cells in response to anoxic incubation. after an acute decrease in temperature (to 10 degrees c) anoxic heat flux dropped by 96% relative to the normoxic control at 25 degrees c. the relative ... | 1993 | 8238601 |
| anoxia-tolerant hepatocytes: model system for study of reversible metabolic suppression. | chrysemys picta bellii is well known for its ability to survive extended anoxic periods and has been widely used as a model system to study anoxic metabolism. described here is a method for the isolation of anoxia-tolerant hepatocytes from this species. freshly isolated hepatocytes were determined to be viable based on trypan blue exclusion, gluconeogenic capacity from [14c]lactate, responsiveness to epinephrine and glucagon, and maintenance of cellular adenylate concentrations. under anoxic con ... | 1993 | 8342699 |
| response of protein synthesis to anoxia and recovery in anoxia-tolerant hepatocytes. | hepatocytes from the western painted turtle (chrysemys picta bellii) display a profound metabolic suppression under anoxia. fractional rates of protein synthesis fell by 92% during 12 h anoxia at 25 degrees c and were indistinguishable from the rate obtained with cycloheximide. normoxic recovery saw protein synthesis increase to 160% of control values and return to normal after 2 h. the gtp-to-gdp ratio, implicated in the control of translation, fell threefold during anoxia. purine nucleotide ph ... | 1993 | 8342698 |
| cytoplasmic droplets of painted turtle spermatozoa. | epididymal sperm from the painted turtle (chrysemys picta) possess a cytoplasmic droplet which is located eccentrically on the sperm midpiece. the droplet contains a large quantity of lipid droplets in addition to hollow vesicles and degenerate mitochondrial fragments. lipid droplets are closely associated with mitochondrial membranes and may function in the formation or degradation of mitochondria. cytoplasmic droplets become detached from the sperm midpiece in a coordinated manner shortly befo ... | 1992 | 23865099 |
| roles of catecholamines and corticosterone during anoxia and recovery at 5 degrees c in turtles. | the roles of the catecholamines and corticosterone in glucose regulation during 28 days of submergence anoxia and air-breathing recovery at 5 degrees c in the turtle chrysemys picta were examined. anoxia resulted in an increase in mean plasma epinephrine and norepinephrine levels (from 42 and 49 to 966 and 3,826 pg/ml, respectively) and a decrease in hepatic glycogen levels. despite the increase in plasma catecholamine levels, plasma glucose levels did not change, and the percent of the alpha fo ... | 1992 | 1415786 |
| responses to freezing exposure of hatchling turtles trachemys scripta elegans: factors influencing the development of freeze tolerance by reptiles. | hatchling red-eared turtles trachemys (= pseudemys) scripta elegans (wied) from a louisiana population display a significant ability to withstand the freezing of extracellular body fluids. all animals survived at least 2 h of freezing at -2.5 or -4 degrees c. at -2.5 degrees c, survival declined to 50% after 6 h of freezing and no animals recovered after 24 h or longer, when mean ice content reached 54.7 +/- 1.4% of total body water. at -4 degrees c, all turtles recovered from 4 h of freezing ex ... | 1992 | 1634864 |
| natural freezing survival by painted turtles chrysemys picta marginata and c. picta bellii. | hatchlings of both the midland (chrysemys picta marginata) and western (c. picta bellii) subspecies of the painted turtle tolerate the freezing of extracellular body fluids while overwintering in terrestrial nests. fall-collected hatchlings survived 3 days of continuous freezing at -2.5 degrees c, with ice contents of 43.5 +/- 1.0% of total body water (se; n = 24) for c. picta marginata and 46.5 +/- 0.8% (n = 32) for c. picta bellii. survival times dropped to 4-5 h when temperature was lowered t ... | 1992 | 1558223 |
| metabolic and cardiodynamic responses of isolated turtle hearts to ischemia and reperfusion. | we used 31p and 1h nuclear magnetic resonance spectroscopy to measure intracellular ph, high energy phosphates, and lactate levels in hearts of turtles (chrysemys picta bellii) subjected to 1.5 h of global ischemia followed by reperfusion. we simultaneously monitored maximum ventricular developed pressure (pmax), maximal rate of pressure development (dp/dtmax), rate-pressure product (rpp), cardiac output, and heart rate and also measured lactate efflux from the hearts during reperfusion. our goa ... | 1992 | 1558214 |
| the effect of anoxic submergence and recovery on circulating levels of catecholamines and corticosterone in the turtle, chrysemys picta. | the ability of some freshwater turtles to tolerate prolonged anoxia is well known. the role of hormones in the regulation of the metabolic adjustments that occur during anoxia, however, is unknown. this study examined the changes in plasma glucose, lactate, catecholamine, and corticosterone levels during submergence anoxia and recovery at 22 degrees c in the painted turtle, chrysemys picta. plasma catecholamine levels increased greatly during anoxia, while corticosterone levels decreased. during ... | 1992 | 1601262 |
| catecholamine stimulation of hepatic glycogenolysis during anoxia in the turtle chrysemys picta. | the remarkable tolerance of some species of turtles to anoxia is well documented. the role that hormones play in this anoxia tolerance, however, is poorly understood. this study examined the role of catecholamines in the mobilization of liver glycogen during anoxic submergence in painted turtles (chrysemys picta). turtles were subjected to 4 h of submergence anoxia or air (normoxic controls) and received injections of propranolol, a beta-adrenergic receptor antagonist, or saline. the results ind ... | 1991 | 1661097 |
| channel arrest: implications from membrane resistance in turtle neurons. | a widespread defense strategy used by hypoxia-tolerant animals is metabolic depression. one possible mechanism for metabolic depression is "channel arrest." this hypothesis predicts that ion leakage through plasma membrane leakage channels is reduced during an anoxic episode. the decreased ion flux would result in the conservation of energy through the reduction of atp-demanding ion pumping. we tested this hypothesis with the anoxia-tolerant turtle (chrysemys picta) as a model system. with intra ... | 1991 | 1719828 |
| allometry of cooling, supercooling, and freezing in the freeze-tolerant turtle chrysemys picta. | although several vertebrates are freeze tolerant, little is known of the relationship between body size and the kinetics of cooling and freezing. we compared these responses for six hatchling and eight adult chrysemys picta from an ohio population. all turtles initially recovered from freezing, and all adults, but only two hatchlings (which experienced ice contents of approximately 35%), exhibited long-term survival. rapid thawing may have compromised hatchling survival. turtle water content was ... | 1991 | 1887950 |
| excitatory amino acid receptor-mediated transmission in geniculocortical and intracortical pathways within visual cortex. | 1. a preparation of turtle (chrysemys picta and pseudemys scripta) brain in which the integrity of the intracortical and geniculocortical pathways in visual cortex are maintained in vitro has been used to differentiate the excitatory amino acid (eaa) receptor subtypes involved in geniculocortical and intracortical synapses. 2. stimulation of the geniculocortical fibers at subcortical loci produces monosynaptic excitatory postsynaptic potentials (epsps) in visual cortical neurons. these epsps are ... | 1991 | 1681038 |
| extracellular and intracellular acid-base effects of submergence anoxia and nitrogen breathing in turtles. | we compared extracellular and intracellular acid-base state in turtles (chrysemys picta bellii) subjected to anoxic submergence to turtles made anoxic by n2-breathing. measurements made on control animals and on animals after 1, 2, 4, or 6 h of anoxia included blood ph, po2, pco2, and lactate as well as liver, heart, skeletal muscle, and brain phi (using dmo equilibration), lactate, and glycogen concentrations. we hypothesized that the anaerobic metabolic rate of submerged turtles would be depre ... | 1991 | 2068419 |
| 31p-nmr measurements of phi and high-energy phosphates in isolated turtle hearts during anoxia and acidosis. | we used 31p-nuclear magnetic resonance (nmr) spectroscopy to measure intracellular ph (phi) and high-energy phosphate levels in hearts of turtles (chrysemys picta bellii) during either 4 h of anoxia [extracellular ph (pho) 7.8, 97% n2-3% co2], 4 h of lactic acidosis (pho 7.0, 97% o2-3% co2), or 1.5 h of combined anoxia + lactic acidosis (pho 7.0, 97% n2-3% co2) followed by 2 h of oxygenated recovery (pho 7.8) at 20 degrees c. we also measured heart rate, maximum ventricular-developed pressure, a ... | 1990 | 2396711 |
| neurotensin is localized to paracrine cells in the urinary bladder of the turtle, chrysemys picta. | urinary bladder from the painted turtle, chrysemys picta, contains a substantial population of endocrine/paracrine cells scattered through the mucosal epithelium which immunostains using antisera directed toward mammalian neurotensin (nt). radiommunoassay of 0.1 n hcl extracts of chrysemys bladder indicated an immunoreactive nt (int) concentration of 161 +/- 39 pmol/g tissue (n = 9), an amount lower but comparable in magnitude to that found in mucosal scrapings of the intestine (926 +/- 125 pmol ... | 1990 | 2202609 |
| force and acid-base state of turtle cardiac tissue exposed to combined anoxia and acidosis. | we measured contractile force of ventricular strips form the turtle chrysemys picta bellii exposed to 1 h of combined anoxia and acidosis (ph 7.0) at 20 degrees c. strips either beat spontaneously (self-paced) or in response to electrical stimulation (paced at 12, 24, or 36 beats/min). tissue [lactate] and intracellular ph (phi) were measured in control strips and at the end of anoxia-acidosis. in self-paced strips, at normal extracellular ca2+ concentration ([ca2+]o) (1 mm), both rate and force ... | 1990 | 2375425 |
| insulin cells are found in the main and accessory urinary bladders of the painted turtle, chrysemys picta. | insulin has been localized immunocytochemically to cells in the main and accessory urinary bladders of the painted turtle, chrysemys picta, and represents an unusual addition to the specturm of regulatory peptides associated with the urinary bladder. these stellate to fibroblastoid cells often possess neural-like processes and are similar in morphology to neurotensin cells found in chrysemys and pseudemys urinary bladders. radioimmunoassay of 2m acetic acid extracts of bladder tissue indicate th ... | 1990 | 2189021 |
| localization of insulin to gastroenteropancreatic cells in the turtle gastrointestinal tract. | insulin has been localized immunocytochemically to open-type gastroenteropancreatic endocrine cells in sections of bouin's-fixed upper, middle, and lower intestine from chrysemys picta, pseudemys scripta scripta, p. scripta elegans, p. floridana, sternotherus odoratus, and trionyx spinifer asper. radioimmunoassay of extracts of mucosal scrapings from chrysemys intestine indicates differential amounts of insulin-like immunoreactivity within the intestine (higher amounts in the lower intestine) an ... | 1990 | 2185121 |
| aerobic metabolism and swimming energetics of the painted turtle, chrysemys picta. | oxygen consumption rates (vo2) were measured for painted turtles (chrysemys picta) swimming in a respirometer at controlled speeds. sustained specific swimming speeds ranged from 0.75 to 1.52 body lengths (l) per s. over most of this range endurance exceeded 30 min. vo2 increased curvillinearly with swimming speed (u) and the maximum active rate was 9 times resting (0.26 ml o2/min), and 3 times routine (0.64 ml o2/min). mass specific metabolic scope was 228 ml o2/(kg.h), similar to that reported ... | 1990 | 2365028 |
| seasonal variation in hepatic binding of estrogen in the turtle, chrysemys picta. | the present study describes the seasonal changes of the estrogen receptor (er) system in the liver of the turtle, chrysemys picta. [3h]estradiol ([3h]e2) binding capacities and affinities of liver cytosols and nuclear extracts were measured with established procedures and analyzed by scatchard plots. our data revealed significant seasonal variations in both receptor content and the er's affinity for [3h]e2 in the liver of the turtle. nuclear er content remained at a fairly stable level of 70 fmo ... | 1989 | 2792733 |
| effects of hypophysectomy and ovariectomy on hepatic estrogen receptor content in the turtle, chrysemys picta. | estrogen receptor (er) content in the cytosol and nuclear extract of the liver of adult female chrysemys picta (control females) was measured in february, may, early june, and late june. both cytosolic (c) and nuclear (n) hepatic er content rose from low levels (c: 189 +/- 19; n: 52 +/- 23 fmol/g tissue) in february to significantly higher levels in may (c: 437 +/- 15; n: 124 +/- 25 fmol/g tissue) before declining to lower values in early june (c: 298 +/- 19; n: 118 +/- 20 fmol/g tissue) and lat ... | 1989 | 2792732 |
| seasonal variations in oviductal activity, extensibility, and tensile strength in chrysemys picta. | in vivo and in vitro myometrial activity, tissue extensibility, and tensile strength were measured during the annual cycle of the female turtle chrysemys picta. contractile rate, in vivo and in vitro, increased to a maximum in the periovulatory period, but contractile strength in vitro was inversely proportional to rate, being least in the periovulatory period. initial oviductal circumference was highest in april and lowest in september. although extensibility varied little, this parameter was i ... | 1988 | 3240854 |
| hatchling turtles survive freezing during winter hibernation. | hatchlings of the painted turtle (chrysemys picta marginata) are unique as the only reptile and highest vertebrate life form known to tolerate the natural freezing of extracellular body fluids during winter hibernation. turtles survived frequent exposures to temperatures as low as -6 degrees c to -8 degrees c in their shallow terrestrial nests over the 1987-1988 winter. hatchlings collected in april 1988 had a mean supercooling point of -3.28 +/- 0.24 degrees c and survived 24 hr of freezing at ... | 1988 | 3186730 |
| sex hormone binding globulin levels and free progesterone, testosterone and estradiol 17 beta during the annual cycle of the female turtle, chrysemys picta. | significant changes in % free serum e2, t and p were observed during the annual cycle of the turtle. in contrast no significant changes in shbg affinity constants (2.29-4.48 x 10(8) m-7) were found and binding capacity for estradiol 17b was between 3.47 and 3.96 x 10(-7) m except in preovulatory animals (2.00 +/- 0.25). | 1988 | 3250020 |
| the annual testicular cycle in the turtle, chrysemys picta: a histochemical and electron microscopic study. | this work is a study of testicular function in chrysemys picta using changes in ultrastructure and steroid histochemistry as indices of leydig and sertoli cell activity. the cytological features of these cells are described in reference to four periods of tubular development. leydig and sertoli cells show distinct changes in morphological appearance during the seasonal cycle. leydig cells are hypertrophic with an active 3 beta-hydroxysteroid dehydrogenase (hsd) and abundant smooth endoplasmic re ... | 1988 | 3203868 |
| brain and cerebrospinal fluid ion composition after long-term anoxia in diving turtles. | prolonged anoxia in turtles is associated with marked disturbances in plasma composition. this study examines brain and cerebrospinal fluid (csf) ion homeostasis in the freshwater turtle, chrysemys picta bellii, in response to 8-10 days of submergence anoxia at 10 degrees c. for comparison, it also examines the response to experimental elevation of plasma [k], [ca], and [mg] in normoxic turtles. long-term anoxia resulted in marked changes in brain and csf composition. these included elevated [k] ... | 1988 | 3136673 |
| hemoglobins of reptiles. the primary structure of the major and minor hemoglobin component of adult western painted turtle (chrysemys picta bellii). | red blood cells of adult western painted turtles (chrysemys picta bellii) contain two hemoglobin components: hba (alpha a2 beta 2) and hbd (alpha d2 beta 2). we present the complete amino-acid sequences of the alpha a-chains from the major component and of the beta-chains common to both components. structural features are discussed with respect to the animals extreme tolerance of severe hypoxic conditions during hibernation which is accompanied by a high oxygen affinity of the hemoglobin. the st ... | 1988 | 3365328 |
| metabolic rate of feeding and fasting juvenile midland painted turtles, chrysemys picta marginata. | 1. resting metabolic rates at 25 degrees c were determined for juvenile midland painted turtles that had recently been fed or fasted for 1, 2, 4, 6, 10, 14 or 19 days. 2. recently fed turtles had an oxygen consumption rate of 211 microliter o2/g/hr. this decreased by 32% on the first day of the fast and by 69% by the 19th day. 3. mass of the turtles (4.91-14.30 g) did not affect the rate of oxygen consumption (vo2). | 1988 | 2900100 |
| effects of thyrotropin-releasing hormone in vitro on thyrotropin and prolactin release from the turtle pituitary. | effects of synthetic thyrotropin-releasing hormone (trh) on thyrotropin (tsh) and prolactin (prl) release by hemipituitaries of adult turtles, chrysemys picta, were studied in an in vitro superfusion system. significant increases in the rates of secretion of both immuno-reactive tsh and prl occurred at doses between 0.01 and 10 ng/ml trh. tsh secretion increased acutely by two-, to sixfold over nonstimulated secretion levels; responses tended to decline after many hours of continual stimulation, ... | 1987 | 3114044 |
| acid-base status and electrolytes in red blood cells and plasma of turtles submerged at 3 degrees c. | two groups of adult chrysemys picta bellii were studied; control turtles were maintained at 24 degrees c with free access to air, and diving animals were continuously submerged for 8.5-9.5 wk in aerated water at 3 degrees c. cold submergence elicited a substantial lactic acidosis (blood ph 7.70; plasma [lactate-] 42.5 meq/l h2o). this acid load was largely balanced by changes in plasma strong ions; [cl-] decreased, and [ca2+] and [mg2+] increased. phosphorus nuclear magnetic resonance showed a s ... | 1987 | 3605391 |
| morphological constraint on egg size: a challenge to optimal egg size theory? | some freshwater turtles appear unable to produce eggs large enough to achieve the balance between size and number of eggs predicted by optimal egg size theory. we present evidence that pelvic girdle structure constrains egg size and thus offspring size in females of smaller-bodied species (chrysemys picta and deirochelys reticularia). the constraint is demonstrated by the correspondence of slopes of the increase of the pelvic aperture and egg width with increasing body size. this constraint appe ... | 1987 | 3473499 |
| characterization of steroid receptors in the gut and kidney of the frog (rana catesbeiana) and in the gut of the turtle (chrysemys picta). | paraglucocorticoid- and paramineralocorticoid-binding cytosolic receptors (pgr, pmr) were demonstrated in the intestine and kidney of the frog, rana catesbeiana and in the intestine of the turtle, chrysemys picta, in the presence of sodium molybdate. these receptors were of high affinity and low capacity with the following binding parameters: pgr:kd:frog intestine (fi), triamcinolone acetonide (ta): 3.3 nm, corticosterone (b): 3.4 nm; frog kidney (fk), ta:4.3 nm, b: 9.3 nm; turtle intestine (ti) ... | 1987 | 3035288 |
| hepatic estrogen receptor in the turtle, chrysemys picta: partial characterization, seasonal changes and pituitary dependence. | a hepatic estrogen receptor is described from female turtles, chrysemys picta. the receptor adheres to dna after incubation with [3h]estradiol and can be eluted with a linear salt gradient as a single component with an elution maximum of 0.21 m. it is steroid-specific, binding estrogens, but not androgens or progestins. specific binding saturates between 3 and 7 nm [3h]estradiol-17 beta and scatchard analysis gave a kd of 2 x 10(-9) m and a maximal binding capacity of 3.02 fmol/mg protein. hypop ... | 1987 | 3821107 |
| ionic compensation with no renal response to chronic hypercapnia in chrysemys picta bellii. | the ionic compensatory response to co2 breathing for 3 days was studied on intact and cystectomized turtles at 10 and 20 degrees c. arterial blood gases, ph, ionized calcium, and the plasma concentrations of na+, k+, cl-, total ca2+, and total mg2+ were measured periodically. at 20 degrees c, ureteral urine was also collected from bladderless turtles and was analyzed for ph, ions, nh3+, total co2, osmolality, and titratable acid. when co2 was breathed there was a compensatory change in the stron ... | 1986 | 3789204 |
| ultrastructure of the dorsal lateral geniculate complex in turtles of the genera pseudemys and chrysemys. | the ultrastructure of the dorsal lateral geniculate complex in the turtles pseudemys scripta elegans and chrysemys picta belli has been studied. the majority of neurons have somata situated in a cell plate that forms the medial face of the complex. relatively few synaptic contacts occur on the somata of cell plate neurons, but three types of axon terminals contact their proximal dendrites as they course through the cell plate. the most frequent are terminals with clear, round synaptic vesicles t ... | 1986 | 3594200 |
| in vivo and in vitro responses to gonadotropin releasing hormone in the turtle, chrysemys picta, in relation to sex and reproductive stage. | in vivo and in vitro responsiveness to gonadotropin releasing hormone (gnrh) was studied in the turtle, chrysemys picta, after manipulation of reproductive condition by temperature: warm temperatures (28 degrees) induced testicular growth and ovarian regression compared to cold (17 degrees) treatment. only males (and primarily from cold treatment) responded to gnrh injection (40 micrograms/100 g body wt intracardiac); correlated increases occurred in plasma lh and testosterone. effects of gnrh ( ... | 1985 | 3932124 |
| the gastro-entero-pancreatic system of the turtle, chrysemys picta. | pancreatic endocrine cells were stained immunocytochemically for insulin, glucagon, somatostatin and pancreatic polypeptide by the pap technique or sequentially for two hormones by the pap followed by an indirect immunogold procedure. pancreatic endocrine cells of chrysemys are found scattered as single cells or small aggregates throughout the exocrine parenchyma; only the splenic region shows islets consisting of a b cell core surrounded by a loose mantle of a cells and occasional d cells. pp c ... | 1985 | 3913912 |
| the viability of nearctic freshwater turtles submerged in anoxia and normoxia at 3 and 10 degrees c. | survival times of temperature-acclimated freshwater turtles submerged in normoxic and anoxic water were determined. juvenile chrysemys scripta from alabama and adult chrysemys picta bellii from wisconsin exhibited the maximal survival times of the 10 species and subspecies investigated, both being able to survive at least a half-year of submergence at 3 degrees c in normoxic water. minimal viability was exhibited by sternotherus odoratus and trionyx spiniferus submerged in anoxia at 10 degrees c ... | 1985 | 2863050 |
| [hemoglobins of reptiles. expression of alpha-d-genes in the turtles, chrysemys picta bellii and phrynops hilarii (testudines)]. | the hemoglobins of two turtles (testudines)--chrysemys picta bellii (suborder cryptodira) and phrynops hilarii (suborder pleurodira)--were investigated. in both specimens we found two hemoglobin components with two distinct alpha-chains. the alpha-chains of the component hbd of chrysemys picta bellii and of the component cii of phyrynops hilarii belong to the alpha d-type, which has so far been reported to occur only in birds. the complete amino-acid sequences of both alpha d-chains are presente ... | 1984 | 6519642 |