Chrysemys Picta Belli Research Articles

Alfaxalone is an effective anesthetic for the electrophysiological study of anoxia-tolerance mechanisms in western painted turtle pyramidal neurons.

Anoxia in the mammalian brain leads to hyper-excitability and cell death; however, this cascade of events does not occur in the anoxia-tolerant brain of the western painted turtle, Chrysemys picta belli. The painted turtle has become an important anoxia-tolerant model to study brain, heart, and liver function in the absence of oxygen, but being anoxia-tolerant likely means that decapitation alone is not a suitable method of euthanasia. Many anesthetics have long-term effects on ion channels and are not appropriate for same day experimentation. Using whole-cell electrophysiological techniques, we examine the effects of the anesthetic, Alfaxalone, on pyramidal cell action potential amplitude, threshold, rise and decay time, width, frequency, whole cell conductance, and evoked GABAA receptors currents to determine if any of these characteristics are altered with the use of Alfaxalone for animal sedation. We find that Alfaxalone has no long-term impact on action potential parameters or whole-cell conductance. When acutely applied to naïve tissue, Alfaxalone did lengthen GABAA receptor current decay rates by 1.5-fold. Following whole-animal sedation with Alfaxalone, evoked whole cell GABAA receptor current decay rates displayed an increasing trend with 1 and 2 hours after brain sheet preparation, but showed no significant change after a 3-hour washout period. Therefore, we conclude that Alfaxalone is a suitable anesthetic for same day use in electrophysiological studies in western painted turtle brain tissue.

A58 UTILIZATION OF HYPOXIA-TOLERANT ORGANISMS AS A MODEL IN THE STUDY OF ISCHEMIC-REPERFUSION INJURY IN TRANSPLANT HEPATOLOGY

Abstract Background Ischemic-reperfusion injury (IRI) is a barrier to successful liver transplantation. This complex process is initiated by an episode of hypoxia and decreased adenosine triphosphate (ATP) production. Mammalian hepatocytes are susceptible to prolonged hypoxia and may experience irreversible damage with ATP depletion. Yet, facultative anaerobes have developed physiological hepatoprotective strategies to tolerate hypoxic stress. The painted turtle (Chrysemys picta belli) and the common goldfish (Carassius auratus) are able to survive under severe hypoxia for weeks to months. Aims Introducing hypoxia-tolerant organisms as a suitable animal model for studying IRI in transplant hepatology. Methods A comprehensive search of PubMed, OVID, CINAHL, and Cochrane databases up to May 2023 was conducted to identify all studies reporting experimental evidence and hepatoprotective pathways in hypoxia-tolerant organisms (HTOs). Each article was qualitatively assessed. The primary focus was on cell death, intracellular ion gradient, mitochondrial function, and reactive oxygen species (ROS) with hypoxia and IRI. Results HTOs have increased glycogen storage with a greater ATP yield from anaerobic metabolism (glycolysis). Approximately 15-30% of liver mass in HTOs is composed of glycogen which is massive compared to 5-6% in mammals. Turtle isolated hepatocytes can tolerate 10 hours of anoxia by reducing cellular metabolic demand by 90% through decreased protein synthesis and ion channel activity. Goldfish hepatocytes can tolerate 6 hours of anoxia via similar strategies. In mammals, mitochondria undergo depolarization, Ca2+ efflux, cellular swelling, and apoptosis with anoxia. Yet, a depolarized mitochondrial membrane potential is regulated to provide cellular protection in HTOs. The ability to preserve mitochondrial function and electrochemical gradients with oxygen lack is an important contributor to cellular survival. Even in mammalian hepatocytes, if the mitochondrial integrity is maintained, cells are better able to tolerate ischemic insults. Finally, formation of radicals with reperfusion leads to hepatocyte apoptosis and necrosis in the mammalian model. Meanwhile, regulated ROS levels in turtles and goldfish cells, prevent cell death and IRI. Conclusions IRI is of significant interest in transplant hepatology. Although extremely valuable, the traditional mammalian models are vulnerable to hypoxia. Meanwhile, HTOs have undergone years of adaptation with thousands of genes dedicated to hypoxia tolerance. Utilizing these organisms can provide a broader understanding of IRI and avoid irreversible tissue damage in transplant hepatology. Funding Agencies CIHR

Evidence of Cold Induced Cytoskeletal Arrest in Hepatocytes of the Western Painted Turtle

The western painted turtle (Chrysemys picta belli) overwinters in ice-covered water bodies and can survive without oxygen (anoxia) for months, during which time metabolic rate decreases so that ATP demand does not exceed anoxic ATP supply. In order to characterize the contribution of the cytoskeleton to overwintering metabolic depression in non-excitable turtle cells, we have optimized a hepatocyte cell culture system. Actin and tubulin cycling are large consumers of cellular ATP pools, and we hypothesized that their cycling activity, and consequently capacity for structural rearrangement, would be downregulated by overwintering conditions. Turtles were acclimated to either 22°C or 4°C for at least 20 days and isolated hepatocytes were plated on either fibronectin or polylysine at varying temperatures, or in cyanide containing media, which acted as a chemical proxy for anoxia. Low incubation temperature, but not cyanide, prevented hepatocytes from forming stable attachment to fibronectin, suggesting inhibition of cell spreading and arrest of actin structural rearrangement by low temperature. Attachment to polylysine, a predominately passive and electrostatic phenomenon, was not inhibited by low temperature or cyanide. Hepatocytes isolated from 4°C acclimated turtles were 30% smaller in 2D area than those of 22°C acclimated turtles. Three-hour cyanide exposure of hepatocytes from 22°C acclimated turtles also resulted in a 30% shrinkage of 2D area, indicating that temperature depression and anoxia may have overlapping inhibitory effects on cell spreading and underlying cytoskeletal turnover. Previous research has shown that cyanide treatment causes reduction of hepatocyte mitochondrial membrane potential. Ongoing work is demonstrating that, regardless of whole animal temperature acclimation, low temperature exposure results in decreased mitochondrial membrane potential as well as increased cytosolic calcium, signaling which may contribute to inhibition of energetically costly actin rearrangement.

The Effect of Intracellular pH on Myocardial Calcium Sensitivity in the Anoxia‐Tolerant Painted Turtle

The anoxia‐tolerant western painted turtle, Chrysemys picta belli, has the ability to survive without oxygen for over 170 days at 3°C due to extreme metabolic responses that minimize energy usage. Under such conditions, the heart minimizes rate and contractility, resulting in a decreased cardiac output. The onset of anoxia is accompanied by a substantial decrease in intracellular pH, which suggests that the reduction in contractility results mostly from mechanical changes in the myofilament sensitivity to Ca2+ associated with intracellular H+ accumulation. To test this hypothesis, the cellular mechanical properties of turtle myocardium were studied at different pH's from turtles exposed to either 24 hours of anoxic or normoxic conditions at 20°C. Multicellular preparations of turtle ventricles were chemically permeabilized and subsequently attached to a motor and force transducer. Preparations were exposed to an array of pCa solutions varying in pH from 7.4 to 6.6 at 22 °C. The concentration of calcium required to trigger 50% of maximum tension (pCa50) decreased stepwise: pCa50 was 6.2, 5.9 and 5.6 for pH's 7.4, 7.0 and 6.6, respectively. The shift in pCa50 indicates that as pH decreases, 50% tension production requires higher calcium levels. Additionally, maximum contractile force decreased as pH decreased. These data indicate that an increased concentration of H+ results in reduced myofilament sensitivity to calcium and, therefore, a decreased ability for force development. Comparisons between normoxic and anoxic tissues indicated no mechanical differences, suggesting that the metabolic changes seen at the onset of anoxia are likely to be a response of intracellular compositional changes of the chemical environment, rather than structural changes to the contractile apparatus. Overall, pCa50 the painted turtle myocardium is intrinsically more sensitive to calcium concentrations (5.9 at pH 7.0) when compared to human and rat (5.67 and 5.2 at pH 7.0), but is similar to other ectotherms.Support or Funding InformationThis work was supported by a CAREER award from the National Science Foundation.

Cardiac pH Regulation and Buffering of the Western Painted Turtle ( Chrysemys picta belli )

The western painted turtle (Chrysemys picta bellii) spends its winters below the ice where oxygen sources are depleted, during which they rely on anaerobic metabolism. During this anoxia, the heart accumulates the highest lactates and has the lowest intracellular pH of any organ, while cardiac function, itself, is depressed. To determine whether the buffering power of the painted turtle ventricle is unique from other vertebrates, we used fluorescence microscopy and ammonium chloride pre-pulsing to measure the pH-dependence of total and intrinsic buffering power in isolated ventricular myocytes. Our data show that painted turtle ventricular myocyte intrinsic buffering is lowest (9-2 mequiv L-1) at the pH ranges that occur during anoxia (pH 7.2-6.55) and is highest (62 mequiv L-1) at normal and alkaline pH's (greater than 7.2), which differs from mammals, where the opposite is observed. The same trend is seen with bicarbonate-dependent buffering, where buffering power drops from 44 mequiv L-1 at pH 7.2 to 2 mequiv L-1 at pH 6.8. A decrease in bicarbonate-dependent buffering with decreased pH has been shown in mammals, but is substantially lower in turtles. This leads to a total buffering of between 53 mequiv L-1 and 4 mequiv L-1 during anoxia. We suggest that a decrease in buffering power at a low pH could be an advantage for the turtle, as H+ are allowed to accumulate more quickly, which will have the effect of preventing cross-bridge cycling and preserving ATP. This study was funded by the National Science Foundation.

Conservation Implications of Initial Orientation of Naïve Hatchling Snapping Turtles (Chelydra serpentina) and Painted Turtles (Chrysemys picta belli) Dispersing From Experimental Nests

We examined the orientation of 76 naïve painted turtles (Chrysemys picta belli) and 746 snapping turtles (Chelydra serpentina) during initial dispersal from experimental nests in the Weaver Dunes area of southeastern Minnesota. We conducted 15 releases into large circular arenas in 4 natural nesting areas and 2 atypical areas. Hatchling orientation and dispersal for both species were 1) all nonrandom, 2) appeared to be based on vision (i.e., nonpolarized light), and 3) toward nearby, open, and highly illuminated horizons, regardless of whether or not they were associated with the wetlands. A first-order estimate of hatchling snapping turtle perception distance was 55–90 m. We found no evidence that suggests that specular light from the wetlands, olfaction, or humidity gradients were important in orientation. At 2 of 3 locations, substantial changes in orientation direction occurred when hatchling snapping turtles were released in morning vs. late afternoon. Changes in dispersal directions in the morning and afternoon indicated that hatchlings were not orienting toward the sun per se but toward different highly illuminated nearby prairie areas. At one site, hatchling orientation in the afternoon (but not in the morning) was toward a nearby wetland and was consistent with either dispersal toward highly illuminated near horizon or with the perception and use of reflected polarized light from the wetland. Collectively, the results from our study also indicate that 1) hatchlings disperse toward open horizons rather than toward wetlands themselves (i.e., open areas that are not necessarily associated with wetlands), 2) dispersal direction is influenced by time of day, apparently because of changes in the degree of illumination of different horizons, and 3) far horizons apparently were not used because they were beyond the perception distance of hatchlings. The most parsimonious evolutionary explanation of solutions to orientation problems is that, for each species, both adults and hatchlings have similar perception distances and use the same sensory modes and types of environmental cues during terrestrial movements. Comprehensive conservation and management plans for aquatic turtles should include consideration of how habitat changes in nesting areas might alter the environmental cues that determine the initial orientation and successful dispersal of hatchlings. We compared the results from this study with the dispersal patterns of naïve hatchling Blanding's turtles (Emydoidea blandingii) that emerge from nests located much farther from wetlands.

Avenues of extrapulmonary oxygen uptake in western painted turtles ( Chrysemys picta belli) at 10 °C

The major avenues of extrapulmonary oxygen uptake were determined on submerged western painted turtles ( Chrysemys picta bellii) at 10 °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, each of the potential avenues was mechanically blocked either singly or in combination; in Series 2, active cloacal and buccal pumping were prevented pharmacologically using the paralytic agent rocuronium. In addition in Series 2, N 2-breathing preceded submergence in some animals and in one set of Series 2 experiments arterial blood was sampled and analyzed for pH, lactate, P O 2 , and P CO 2 . Results in both Series 1 and Series 2 revealed that prevention of cloacal and/or buccopharyngeal exchange did not significantly affect total O 2 uptake. Interfering with skin diffusion in Series 1, however, significantly reduced O 2 uptake by 50%. N 2-breathing prior to submergence in Series 2 did not affect O 2 uptake in paralyzed turtles but significantly increased uptake in unparalyzed turtles without catheters. Blood analysis revealed that all submerged turtles developed lactic acidosis, but the rate of rise in lactate was significantly lower in paralyzed animals. We conclude that passive diffusion through the integument is the principal avenue of aquatic O 2 uptake in this species.

Helminth Parasites of the Western Painted Turtle, Chrysemys picta belli (Gray), including Neopolystoma elizabethae n. sp. (Monogenea: Polystomatidae), a Parasite of the Conjunctival Sac

Helminth Parasites of the Western Painted Turtle, Chrysemys picta belli (Gray), including Neopolystoma elizabethae n. sp. (Monogenea: Polystomatidae), a Parasite of the Conjunctival Sac

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. All are common parasites of North American freshwater turtles. An additional species of Monogenea (Polystomoidespauli) was found in the oral cavity. Four species of Digenea (Eustomos chelydrae, Allassostomoides chelydrae, Spirorchis kirki, and Spirorchis parvus) and 3 species of Nematoda (Spiroxys contorta, Serpinema trispinosus, and Amphibiocapillaria serpentina) were also found. The following are reported from Michigan for the first time: P. pauli, S. kirki, and A. serpentina.

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 consumption was measured in reptilian N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid-buffered Ringer solution and in nomially Na(+)- and Ca(2+)-free solution, thus estimating the Na+ pump component of metabolic rate. Lowering extracellular pH from 7.8 to 7.0 resulted in a significant increase in metabolic rate of cells in Ringer solution but not those in Na(+)- and Ca(2+)-free solution. This result was unchanged by the addition of 2 mM Ca2+ to Na(+)-free cell suspensions, indicating that the difference was due to the presence of Na+. Addition of 100 microM amiloride to cells in Ringer solution at pH 7.0 abolished the increase in O2 consumption, suggesting that the apparent increase in Na(+)-K(+)-ATPase activity was secondary to Na(+)-H+ exchange. Intracellular pH was measured using 5,5-dimethyl[14C]oxazolidine-2,4-dione. Cells treated with amiloride and those in Na(+)- and Ca(2+)-free solution did not regulate intracellular pH following acidosis and maintained basal metabolic rate. These data suggest that the Na(+)-H+ exchanger is an important contributor to intracellular pH regulation in the myocyte but increases Na+ pump activity and metabolic rate immediately following acidosis.

Effect of Drought on the Western Painted Turtle,Chrysemys picta belli, in a Small Wetland Ecosystem

Abstract Middle Findley Lake, a small watershed located on the Turnbull Wildlife Refuge in Washington, dried up late in the summers of 1987 and 1988. Water remained in the lake in 1989. Population size of the western painted turtle (Chrysemys picta belli) decreased by approximately 70 percent following two years drought, with indications that both mortality and emigration contributed to this reduction. Growth of individual turtles was markedly suppressed during the second drought year when compared to the first year of recovery, but not to the point that the average sizes of cohorts were affected.

Ultrastructure of the Dorsal Lateral Geniculate Complex in Turtles of the Genera <i>Pseudemys </i>and <i>Chrysemys</i> (Part 2 of 2)

The ultrastructure of the dorsal lateral geniculate complex in the turtles <i>Pseudemys scripta elegans </i>and <i>Chrysemys picta belli </i>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 that form asymmetric junctional complexes. A second type has both clear and round, and dense-cored vesicles and forms asymmetric junctional complexes. The third type has clear, pleomorphic vesicles and forms symmetric junctional complexes. The same three types of terminals are presynaptic to the dendrites of cell plate neurons as they proceed through the inner half of the geniculate neuropile that is interposed between the cell plate and optic tract. These dendrites branch into varicose, finger-like distal dendrites within the outer half of the neuropile. The finger-like processes contain clear, pleomorphic vesicles and are linked with each other via dendrodendritic synapses with symmetric junctional complexes. The distal dendrites are postsynaptic to axon terminals with clear, round synaptic vesicles and asymmetric junctional complexes.Cell plate neurons thus comprise three regions, each with a distinct synaptic organization. The first region is formed by the somata of cell plate neurons and receives few synaptic contacts. The second region is formed by the proximal dendrites both in the cell plate and the inner half of the neuropile. It receives a moderate contingent of axodendritic terminals. The last region is formed by the distal dendrites of the cell plate neurons. They participate in dendrodendritic synapses and are postsynaptic to axon terminals with clear, round synaptic vesicles.

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 that form asymmetric junctional complexes. A second type has both clear and round, and dense-cored vesicles and forms asymmetric junctional complexes. The third type has clear, pleomorphic vesicles and forms symmetric junctional complexes. The same three types of terminals are presynaptic to the dendrites of cell plate neurons as they proceed through the inner half of the geniculate neuropile that is interposed between the cell plate and optic tract. These dendrites branch into varicose, finger-like distal dendrites within the outer half of the neuropile. The finger-like processes contain clear, pleomorphic vesicles and are linked with each other via dendrodendritic synapses with symmetric junctional complexes. The distal dendrites are postsynaptic to axon terminals with clear, round synaptic vesicles and asymmetric junctional complexes. Cell plate neurons thus comprise three regions, each with a distinct synaptic organization. The first region is formed by the somata of cell plate neurons and receives few synaptic contacts. The second region is formed by the proximal dendrites both in the cell plate and the inner half of the neuropile. It receives a moderate contingent of axondendritic terminals. The last region is formed by the distal dendrites of the cell plate neurons. They participate in dendrodendritic synapses and are postsynaptic to axon terminals with clear, round synaptic vesicles.

Leech Parasitism on the Western Painted Turtle, Chrysemys picta belli, in Saskatchewan

Freshwater turtles are common hosts of leeches (Hirudinea). Recently Ernst (1971, J. Parasitol. 57: 32) and McAuliffe (1977, ibid. 63: 580-581) reported on leech infestations in the painted turtle, Chrysemys picta. A study of the western painted turtle, C. p. belli, was carried on during the months of May through August of 1978 and 1979. The study area was a portion of the Qu'Appelle River in south central Saskatchewan, approximately 30 km northwest of Regina. The Qu'Appelle River, part of the Hudson Bay drainage system, is narrow, meandering, and sluggish, and is the northern limit of the range of painted turtles in Saskatchewan. Turtles were captured by dip net from a boat. The leech, Placobdella parasitica Say, was common in the river and often was found attached to turtles. During 1979, 75 individual turtles were examined. The number of times a turtle was captured during the season varied from one to 22. In all, there were 191 captures of turtles; 62 (32%) of these were parasitized. Ernst and Ernst (1973, J. Minnesota Acad. Sci. 38: 77-80) found leeches on only three individuals (4.2%) of Chrysemys picta belli captured in Minnesota; Ernst (loc. cit.) found leeches on 10.7% of a Pennsylvania sample of C. picta and McAuliffe (loc. cit.) found leeches on 39% of C. p. belli captured in Nebraska. In my study, 102 captures were of males, of which 32 (31%) were parasitized. Twentynine (45%) of the 65 females were parasitized. Of the 24 juveniles only one (4%) was parasitized. Chi-square tests showed that only juveniles differed significantly from the total sample in the percentage of parasitized individuals captured (P < 0.01). Comparison among males, females, and juveniles using chi-square tests showed no difference between males and females, but significant differences between both juveniles and males and juveniles and females (P < 0.01) with respect to the percentage of parasitized turtles captured. A total of 171 leeches was attached to the turtles captured-a mean of 0.9 leeches per turtle. The 62 parasitized individuals had a mean of 2.8 leeches per turtle. Ernst (loc. cit.) found a mean of 2.4 leeches per parasitized turtle, whereas McAuliffe (loc. cit.) stated that usually only one or two leeches were present on a parasitized individual. In this study, parasitized males had a mean of 2.3 leeches per turtle, whereas females had an average of 3.2 leeches per turtle, and the single parasitized juvenile had four leeches attached. A MannWhitney U-test showed that there was no difference between males and females in the number of leeches per parasitized turtle, but only females had more than six leeches present at one time. Most leeches attached to the limbs or limb sockets; fewer were found on the tail, neck, and shell. The number of leeches per parasitized turtle from this study and from Pennsylvania (Ernst, loc. cit.) is shown in Table I. Chi-square tests showed that significantly more Pennsylvania turtles than Saskatchewan turtles had one leech attached

Helminths of Chrysemys picta belli in Manitoba including Polystomoides pauli sp.n. (Monogenea: Polystomatidae)

One new monogenean is described and 11 other helminths are reported from painted turtles from eastern Manitoba. Polystomoides pauli sp.n. from the host's oral mucosa most closely resembles P. coronatum (Leidy) and P. oris Paul. It differs from the former in having more and larger genital coronet spines, and possession of anterior cecal diverticula, and from the latter in size, larger number of genital coronet spines, and possession of great hooks with entire, not bifid, roots. Price's emendation of P. coronatum to include five species he held to be its synonyms is rejected; and the five species, P. opacum Stunkard, P. megacotyle Stunkard, P. microcotyle Stunkard, P. albicollis MacCallum, and P. digitatum MacCallum are designated species inquirendae. Polystomoides coronatum is restricted to the redescription given for it by Stunkard. The trematodes Crepidostomum sp., Eustomos chelydrae, Microphallus opacus, Protenes angustus, Spirorchis parvus, S. scripta, Telorchis attenuatus, and T. corti, the cestode Proteocephalus sp., and the nematodes Serpinema trispinosa and Spiroxys contortus are reported from Chrysemys picta belli. Except for P. angustus, all represent first reports from turtles in Canada. This is the first report of E. chelydrae from the host stomach, and the second report of M. opacus from naturally infected turtles.

Coccidian Parasites from Iowa Turtles: Systematics and Prevalence*

SYNOPSIS. A survey of 22 Western Painted Turtles (WPT), Chrysemys picta belli Gray; 2 Map Turtles (MT), Graptemys geographica Le Sueur; 8 False Map Turtles (FMT), Graptemys pseudogeographica Gray; 26 Illinois Mud Turtles (IMT), Kinosternon flavescens spooneri Smith; and 5 Spiny Softshell Turtles (SST), Trionyx spiniferus Le Sueur, revealed the presence of 10 species of coccidia. The species found, the shape and average length‐width dimensions (in micrometers) of their oocysts, and the respective hosts from which they were isolated were as follows: Eimeria chrysemydis Deeds &amp; Jahn, slightly pear‐shaped (27.6 × 17.0), from 5 WPTs; Eimeria delagei marginata Deeds &amp; Jahn, markedly pearshaped (22.1 × 17.6), from 2 WPTs, 1 MT, and 3 FMTs; Eimeria graptemydos sp. n., broadly ellipsoid to subspherical (12.6 × 11.4), from 10 WPTs, 2 MTs, and 5 FMTs; Eimeria lutotestudinis sp. n., broadly ellipsoid to subspherical (11.9 × 10.8), from 4 IMTs; Eimeria mascoutini sp. n., broadly ellipsoid to subspherical with outer surface of oocyst wall mammillated (14.0 × 11.9), from 2 SSTs; Eimeria mitraria (Laveran &amp; Mesnil), asymmetrically ellipsoid, bearing 1 or 2 conical projections at the polar end and 2 or 3 at the antipolar end (10.0 × 7.6), from 7 WPTs, 1 MT, 3 FMTs, and 4 IMTs; Eimeria pseudogeographica sp. n., narrowly ellipsoid to slightly ovoid (19.5 × 13.5), from 5 WPTs and 3 FMTs; Eimeria tetradacrutata sp. n., spherical to subspherical with outer surface of oocyst wall mammillated (19.5 × 19.2), from 1 WPT; an Eimeria sp. narrowly ellipsoid, bearing 2 conical projections at the polar end and 2 at the antipolar end (23.8 × 13.2), from 1 MT; and Mantonella hammondi sp. n., conical to narrowly ellipsoid, bearing 1 conical projection at the polar end and 2 or 3 at the antipolar end (14.3 × 7.1), from 1 IMT. The overall infection rate for the 63 turtles examined was 54.0%.

The effects of induced cold torpor and time of year on blood coagulation in Pseudemys scripta elegans and Chrysemys picta belli

1. 1. During a consecutive 13-month period, whole blood coagulation times, prothrombin clotting times and the Hicks-Pitney test for thromboplastin generation were determined for new groups of cold-torpid and room-temperature Pseudemys and Chrysemys turtles. 2. 2. Significant differences in the above-mentioned measurements were found between the two species and the two environmental temperatures. 3. 3. The prothrombin clotting times of Chrysemys turtles were higher than those of Pseudemys turtles during each month of the 13-month study. 4. 4. The low levels of thromboplastin generation suggest that turtles may bypass the plasma coagulation system and rely on vasoconstriction and rapid liberation of tissue thromboplastin when injured.

Effect of hypophysectomy on renal function in the Western painted turtle ( Chrysemys picta belli)

There was a linear relationship between creatinine clearance and urine flow rates in Western painted turtles. Changes in creatinine clearance probably occurred in response to changes in the number of functioning glomeruli. One week after hypophysectomy there was a significant increase in both glomerular filtration rate and free water clearance but relative free water clearance did not change. The increased excretion of Na + and Cl − relative to the amounts filtered may have been due to reduced adrenocortical activity.

Antidiuretic effect of arginine vasotocin in the Western painted turtle ( Chrysemys picta belli)

A reduction in glomerular filtration rate (GFR), urine flow rate, and relative free water clearance occurred within 30 min of an intravenous injection of 10 ng/kg of arginine vasotocin. AVT increased the fraction of filtered sodium excreted ( C Na GFR ) but decreased the net rate of sodium exeretion.

Ionoregulatory responses of the hypophysectomized turtle Chrysemys picta to osmotic stresses

The effects of dehydration and hydration on sodium and potassium levels of plasma and urine were studied in sham-operated and hypophysectomized winter turtles. Hydration resulted in a decrease in plasma sodium whereas dehydration produced an increase in both sodium and potassium. Plasma electrolyte concentrations of hypophysectomized turtles were similar to sham-operated controls under all environmental conditions studied. In urine, concentrations of sodium and potassium were temporarily elevated by dehydration but unaffected by hydration. Hypophysectomy had no effect on urine electrolytes except during dehydration, where hypophysectomized turtles produced urine with low sodium and high potassium. We conclude that the pituitary has little influence on osmoregulation in Chrysemys picta belli during the winter.