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PubMedDate not supplied

The influence of agricultural and urban contamination on leech infestation of freshwater turtles, Phrynops geoffroanus, taken from two areas of the Uberabinha River.

Infestation by leeches on adult freshwater turtles Phrynops geoffroanus in two areas of the Uberabinha River, in Uberlândia, was investigated during the summer (January 2000). Fifty eight turtles were trapped: 26 (12 males, 14 females) in an agricultural area and 32 (16 males, 16 females) in an area with a more urban environment. The females present larger length and body mass (291.77+/-29.18 mm; 2233.30+/-511.40 g) than males (259.71+/-33.15 mm; 1488.68+/-529.35 g). Blood samples were drawn from the retrorbital sinus using heparinized micro-hematocrit capillary tubes, for microscopic and direct examination for intracellular parasites. Ectoparasitism by leeches, Placobdella bistriata, on young and adult animals was observed in the limb cavities of 28.1% of the urban area turtles. No leeches were found on the turtles in the agricultural area. Hemogregarine erythrocytic gametocytes were found in 15.4% of the agricultural area turtles, and in 37.5% of the urban area turtles. Concurrent parasitism by leeches and hemogregarines on the same individuals was seen on six turtles. Infections with microorganisms (bacteria and fungus) facilitated by the bites of leeches were not observed in another study on the same sample of infested turtles. However, 19% of the turtles collected in the agricultural area and 15% of the turtles from the urban area presented normocytic acute anemia. The occupation of the soil apparently interfered in the aquatic ecosystem favoring parasitism in the urban area.

Animals↗
PubMed1988

In vivo environmental temperature and the in vitro pattern of luminal acidification in turtle bladders. Evidence for HCO3 ion reabsorption.

In this study, it is shown how to transfer tared aliquots of (HCO3 + CO2)-containing luminal fluids directly into the mercury-sealed chamber of a modified Van Slyke apparatus and how to obtain direct as well as indirect manometric determinations of dissolved CO2 ([CO2]f) in each aliquot of such fluids. It is next shown that the pattern of in vitro luminal acidification in an isolated turtle bladder sac depends upon the prior in vivo ambient temperature to which the donor turtle had become adapted. Under in vivo conditions, the food intake, physical activity, and acid excretion of 32 degrees C-adapted turtles are greater than those of 21 degrees C or 26 degrees C-adapted turtles. Under in vitro conditions of incubating isolated bladder sacs (from 21, 26, and 32 degrees C turtles) in (HCO3 + CO2)-containing Ringer media at a single temperature (21 degrees C), the patterns of luminal acidification are as follows: (a) The rate of depletion of luminal [HCO3] is greatest in bladders from the 32 degrees C-adapted turtles. (b) Concomitant decreases in luminal [CO2]f, [HCO3], and pH (the 'CO2-decreasing patterns' of luminal acidification) develop in all bladders from 32 degrees C turtles, in half of those from 26 degrees C turtles, but in less than one-fifth of those from 21 degrees C-adapted turtles: and (c) a CO2-increasing pattern of luminal acidification is found in most of the bladders from 21 degrees C-adapted turtles. A postulated bicarbonate ion-reabsorbing pump is consistent with all of these patterns of luminal acidification.

Absorption↗
PubMed2001

Detection of antibodies to a disease-associated herpesvirus of the green turtle, Chelonia mydas.

Lung-eye-trachea disease-associated herpesvirus (LETV) is linked with morbidity and mortality in mariculture-reared green turtles, but its prevalence among and impact on wild marine turtle populations is unknown. An enzyme-linked immunosorbent assay (ELISA) was developed for detection of anti-LETV antibodies and could distinguish LETV-exposed green turtles from those with antibodies to fibropapillomatosis-associated herpesvirus (FPHV). Plasma from two captive-reared green turtles immunized with inactivated LETV served as positive controls. Plasma from 42 healthy captive-reared green turtles and plasma from 30 captive-reared green turtles with experimentally induced fibropapillomatosis (FP) and anti-FPHV antibodies had low ELISA values on LETV antigen. A survey of 19 wild green turtles with and 27 without FP (with and without anti-FPHV antibodies, respectively) identified individuals with antibodies to LETV regardless of their FP status. The seroprevalence of LETV infection was 13%. The presence of antibodies to LETV in plasma samples was confirmed by Western blot and immunohistochemical analyses. These results are the first to suggest that wild Florida green turtles are exposed to LETV or to an antigenically closely related herpesvirus(es) other than FPHV and that FPHV and LETV infections are most likely independent events. This is the first ELISA developed to detect antibodies for a specific herpesvirus infection of marine turtles. The specificity of this ELISA for LETV (ability to distinguish LETV from FPHV) makes it valuable for detecting exposure to this specific herpesvirus and enhances our ability to conduct seroepidemiological studies of these disease-associated agents in marine turtles.

Animals↗
PubMed2005

Spinal cord injury-induced changes in breathing are not due to supraspinal plasticity in turtles (Pseudemys scripta).

After occurrence of spinal cord injury, it is not known whether the respiratory rhythm generator undergoes plasticity to compensate for respiratory insufficiency. To test this hypothesis, respiratory variables were measured in adult semiaquatic turtles using a pneumotachograph attached to a breathing chamber on a water-filled tank. Turtles breathed room air (2 h) before being challenged with two consecutive 2-h bouts of hypercapnia (2 and 6% CO2 or 4 and 8% CO2). Turtles were spinalized at dorsal segments D8-D10 so that only pectoral girdle movement was used for breathing. Measurements were repeated at 4 and 8 wk postinjury. For turtles breathing room air, breathing frequency, tidal volume, and ventilation were not altered by spinalization; single-breath (singlet) frequency increased sevenfold. Spinalized turtles breathing 6-8% CO2 had lower ventilation due to decreased frequency and tidal volume, episodic breathing (breaths/episode) was reduced, and singlet breathing was increased sevenfold. Respiratory variables in sham-operated turtles were unaltered by surgery. Isolated brain stems from control, spinalized, and sham turtles produced similar respiratory motor output and responded the same to increased bath pH. Thus spinalized turtles compensated for pelvic girdle loss while breathing room air but were unable to compensate during hypercapnic challenges. Because isolated brain stems from control and spinalized turtles had similar respiratory motor output and chemosensitivity, breathing changes in spinalized turtles in vivo were probably not due to plasticity within the respiratory rhythm generator. Instead, caudal spinal cord damage probably disrupts spinobulbar pathways that are necessary for normal breathing.

Adaptation, Physiological↗
PubMed1989

Relationship between energy expenditure and ion channel density in the turtle and rat brain.

Synaptosomes were isolated from turtle and rat brains to determine whether differences in brain ion channel densities accounted for the turtle's ability to survive anoxia compared with the mammal. The Na(+)-channel binding neurotoxin brevetoxin showed high-affinity specific binding in both turtle and rat synaptosomes, suggesting specific ligand-receptor interaction. The maximum binding capacity (Bmax) value for the turtle was only about one-third of that found for the rat synaptosomes, suggesting that the turtle synaptosome has a correspondingly lower Na+ channel density than the rat. This apparent difference in Na+ channel density is not reflected in metabolic rates, since at the same temperature (31 degrees C) the O2 consumption of both the rat and turtle synaptosome was almost identical. The large reductions in energy expenditure seen in synaptosomes incubated in Na(+)-free media and in media containing ouabain (approximately 50% turtle, 80% rat) are probably related to the halting of transmembrane Na(+)-K+ exchange. The greater reduction in the rat may be related to the apparent greater density of Na+ channels in the rat brain. However, compared with the 90% reduction in brain metabolism that occurs when the turtle brain becomes anoxic, the differences in ion channel density and in the costs of ion pumping between the rat and turtle brain are trivial. Closing Na+ channels with tetrodotoxin and increasing Na+ channel activation with veratridine caused substantial decreases and increases in synaptosome energy consumption, respectively. This suggests that the modulation of ion channel conductance has a significant effect on metabolic cost and may be an important mechanism to reduce energy consumption and electrical activity in the anoxic turtle brain, while still maintaining ionic gradients.

Animals↗
PubMed2006

The complete mitochondrial genome of the enigmatic bigheaded turtle (Platysternon): description of unusual genomic features and the reconciliation of phylogenetic hypotheses based on mitochondrial and nuclear DNA.

BACKGROUND: The big-headed turtle (Platysternon megacephalum) from east Asia is the sole living representative of a poorly-studied turtle lineage (Platysternidae). It has no close living relatives, and its phylogenetic position within turtles is one of the outstanding controversies in turtle systematics. Platysternon was traditionally considered to be close to snapping turtles (Chelydridae) based on some studies of its morphology and mitochondrial (mt) DNA, however, other studies of morphology and nuclear (nu) DNA do not support that hypothesis. RESULTS: We sequenced the complete mt genome of Platysternon and the nearly complete mt genomes of two other relevant turtles and compared them to turtle mt genomes from the literature to form the largest molecular dataset used to date to address this issue. The resulting phylogeny robustly rejects the placement of Platysternon with Chelydridae, but instead shows that it is a member of the Testudinoidea, a diverse, nearly globally-distributed group that includes pond turtles and tortoises. We also discovered that Platysternon mtDNA has large-scale gene rearrangements and possesses two, nearly identical, control regions, features that distinguish it from all other studied turtles. CONCLUSION: Our study robustly determines the phylogenetic placement of Platysternon and provides a well-resolved outline of major turtle lineages, while demonstrating the significantly greater resolving power of comparing large amounts of mt sequence over that of short fragments. Earlier phylogenies placing Platysternon with chelydrids required a temporal gap in the fossil record that is now unnecessary. The duplicated control regions and gene rearrangements of the Platysternon mtDNA probably resulted from the duplication of part of the genome and then the subsequent loss of redundant genes. Although it is possible that having two control regions may provide some advantage, explaining why the control regions would be maintained while some of the duplicated genes were eroded, examples of this are rare. So far, duplicated control regions have been reported for mt genomes from just 12 clades of metazoans, including Platysternon.

Animals↗
PubMed2005

Epizootiology of spirorchiid infection in green turtles (Chelonia mydas) in Hawaii.

We describe the epizootiology of spirorchiid trematode infections in Hawaiian green turtles (Chelonia mydas) by quantifying tissue egg burdens in turtles submitted for necropsy and by assessing antibody response to crude adult worm and egg antigens among a variety of age groups. Hapalotrema sp. and Laeredius sp. predominated in turtles infected with spirorchiids. Tissue egg burdens decreased with increasing size and increased with deteriorating body condition of turtles. No relationship was found between tissue egg burdens and sex or fibropapillomatosis status. Tissue egg burdens increased in turtles from southeast to northwest in the main Hawaiian Islands (Hawaii to Kauai). Hatchling and captive-reared turtles had significantly lower levels of antibodies against crude worm and egg antigens. Based on tissue egg burdens and antibody status, we hypothesize that immature turtles become infected with spirorchiids shortly after recruiting into coastal foraging pastures from the pelagic environment, that infection levels decrease with age, and that spirorchiids detrimentally affect the body condition of sea turtles independent of tumor burden. The low intensity of infection in turtles with the endemic trematode Carettacola hawaiiensis suggests either that turtles are less susceptible to infection with this parasite or that the parasite is outcompeted by species of Hapalotrema and Laeredius. Given that the 2 latter species are found in the Pacific and other oceans, they are not likely endemic and were probably introduced into Hawaii through an undetermined route.

Animals↗
PubMed1998

[Molecular identification of the Chinese drug turtle shells].

This paper reports a new method to identify the Chinese drug turtle shells using PCR product direct sequencing method. DNA was extracted from tissues of the Chinese three-keeled pond turtle Chinemys reevesii and 20 other species of turtles occurring in China and Southeast Asian countries. One hundred and ten base pairs of mitochondrial 12S rRNA gene fragment were amplified from the extract using PCR technique and obtained sequences. These sequences were used to construct 12S rRNA gene fragment sequence database for the 21 turtle species. Comparison of these sequences indicated that the sequence from the Chinese three-keeled pond turtle is different from that of all the other 20 turtle species. The sequence divergence is 3.7-15.7%. DNA was extracted from 0.1-0.5 g of shell from 19 turtle shells provided by the Jiangsu Institute for Drug Control and 12S rRNA gene fragment was amplified and sequenced. Comparison of the sequences from the 19 turtle shells and 12S rRNA gene fragment sequence database indicated that only 3 samples are shells of the Chinese three-keeled pond turtle specified in the Phamacopoeia of the People's Republic of China and the others are substitutes. The technique used in the present paper was found to be effective and reliable for the identification of turtle shells.

Animals↗
PubMed1980

Turtle-associated salmonellosis in the United States. Effect of Public Health Action, 1970 to 1976.

We examined the effect of state and federal legislative actions on the incidence of human salmonellosis associated with pet turtles. Using the Salmonella Surveillance System of the Center for Disease Control, we identified Salmonella serotypes that were and were not specifically turtle associated. From 1970 to 1976, there was a 77% reduction in frequency of turtle-associated serotypes and no consistent trend among non-turtle-associated serotypes. Decrease in frequency of turtle-associated serotypes correlated best with decrease in total production of pet turtles. Reduction in turtle-associated sertotypes temporally correlated with an 18% reduction in frequency of salmonellosis in children, aged 1 to 9 years. Frequency of turtle-associated serotypes rapidly fell in states importing turtles, in contrast to states producing them. Continued although infrequent occurrence of salmonellosis in children with pet turtles counsels against relaxing legislation concerned with its control.

Animals↗
PubMed1997

Ca2+ activated myosin-ATPase in cardiac myofibrils of rainbow trout, freshwater turtle, and rat.

The Ca(2+)-activated myosin-ATPase and its dependence on hypoxia were assessed in freshwater turtle, rainbow trout, and in some cases rat. At 20 degrees C and pH 7.3, the maximal ATPase activity was (mean +/- SEM): turtle 0.040 +/- 0.003, trout 0.090 +/- 0.005, and rat 0.12 +/- 0.004 mmol*min-1*g-1 myofibrillar dry weight. The turnover number was about three times lower for turtle than for trout. Trout is typically active at lower temperatures than turtle, and its myosin-ATPase activity was about three times lower at 10 degrees than at 20 degrees C. Addition of 12 mM phosphocreatine showed that the myosin-ATPase activity covered by myofibrillar creatine kinase was 22 +/- 2% for turtle, 14 +/- 2% for trout, and 69 +/- 5% for rat. At pH 6.8 relative to 7.3, the maximal M-ATPase activity was the same, whereas the Ca(2+)-sensitivity decreased, and more so for trout than for turtle. This difference disappeared, when trout myocardium was examined at 10 degrees C. P(i) (15 mM) affected neither maximal activity nor Ca(2+)-sensitivity. ADP, however, reduced maximal myosin-ATPase activity, and more so in trout than in turtle. In conclusion, the "slow"-type myosin, the low sensitivity of acidification and ADP, and the high creatine kinase/myosin-ATPase ratio in turtle relative to trout accord with the well-known ability of turtle myocardium to work during hypoxia. However, the difference in living temperature between turtle and trout obscures the situation (e.g. inclusion of rat data suggests that the creatine kinase/myosin-ATPase ratio is related to temperature.

Adenosine Diphosphate↗
PubMed1988

Spermiogenesis in the red-ear turtle (Pseudemys scripta) and the domestic fowl (Gallus domesticus): a study of cytoplasmic events including cell volume changes and cytoplasmic elimination.

Nuclear and cytoplasmic volume changes as well as the elimination of residual spermatid cytoplasm were investigated in the red-ear turtle (Pseudemys scripta) and the rooster (Gallus domesticus). Nuclei of newly formed spermatids which were originally centrally located became eccentrically located within the cell in both species. Shortly thereafter the nuclear pole of the spermatid was found situated within deep crypts of a Sertoli cell. The cytoplasm of elongating spermatids was displaced along the nonacrosomal region of the nucleus and the proximal flagellum. In both species sheetlike Sertoli cell processes indented spermatid cytoplasm adjacent to the nucleus and appeared to segregate small packets of the cytoplasm. In the turtle, these packets of cytoplasm were separated from the spermatid. In both the turtle and rooster, a portion of the spermatid cytoplasm was displaced forward over the acrosomal region of the spermatid to resemble a hood. As spermatids were transported to the seminiferous tubular lumen, cytoplasmic lobes which projected forward of the spermatid head were formed by preferential flow of cytoplasm into one aspect of the cytoplasmic hood. In both species, at sperm release the cytoplasmic lobe was disengaged from the spermatid head to form a large residual body that was internalized and degraded within the Sertoli cell. Medium-sized cytoplasmic lobes were pinched from the head and neck region of the turtle and rooster spermatids, respectively. In the turtle, small-sized mitochondrial-rich cytoplasmic fragments budded from the caudal head and midpiece of the spermatids and were phagocytosed by the Sertoli cell. Thus, cytoplasmic elimination occurred through 1) segregation of cytoplasmic packets by Sertoli penetrating processes (turtle), 2) elimination of large and medium-sized residual bodies from the head (turtle and bird), and 3) budding of small mitochondrial-rich cytoplasmic fragments from the region of the midpiece (turtle). In the turtle a 79% reduction in total cell volume occurred during spermiogenesis which was the result of an 84% cytoplasmic reduction and a 78% nuclear reduction. During spermiogenesis, the rooster lost 97% of its total cell volume due to a 97% cytoplasmic volume change and a 96% nuclear volume change.

Animals↗
PubMed1993

Comparative studies of thyroxine binding proteins in turtle plasma using column chromatography.

Thyroxine (T4) binding proteins in turtle plasma were compared with those of various mammalian and nonmammalian (fish, birds) species using gel filtration chromatography (Bio-Gel). High-affinity T4 binding was observed in all mammals studied, in the chicken, and in one species of turtle, Trachemys scripta. This high affinity T4 binding protein (TBP) appears to be the major component of T4 transport in the turtle; selective removal of this TBP greatly diminished binding activity in T. scripta plasma. In all other nonmammalian species studied (including other turtles), T4 binding appeared to be associated primarily with relatively low affinity components such as albumin. Albumin concentrations in turtle (T. scripta, and Chelydra serpentina) plasmas were examined by measurement of dry weight, protein assay (Bradford), radioimmunoassay, and electrophoretic densitometry. While C. serpentina may have total protein concentrations approaching that of human plasma, albumin content in both turtles was estimated at about 3-4 mg/ml, less than 10% that of human plasma albumin; larger molecular weight components that do not bind T4 comprise a greater proportion of turtle plasma protein. Additionally, purified T. scripta albumin exhibits lower T4 binding than does human albumin; binding to turtle albumin is also reduced by fatty acids. Taken together, these results indicate a lesser role for albumin in plasma T4 binding in T. scripta than in humans, and, thus, a larger role for the T4 binding protein, TBP. Other turtles lacking a TBP may rely wholly on low affinity albumin binding that also has a lower capacity than that in mammals.

Adult↗
PubMed2000

Evidence for a hormonal tactic maximizing green turtle reproduction in response to a pervasive ecological stressor.

Mortality of breeding sea turtles due to excessive heat exposure after nesting activities is an unusual feature of the Raine Island green turtle rookery. Breeding turtles that fail to return to the ocean after oviposition can experience increasing body temperatures that exceed lethal limits (>39 degrees C) as ambient temperatures rise after sunrise. We investigated how acute increases in body temperature influenced plasma corticosterone (B) concentrations of individual turtles. Furthermore, interactions between progesterone (P) and testosterone (T) and increasing body temperature and the glucocorticoid corticosterone were examined for negative correlations. Breeding green turtles exhibited a 16-fold mean increase in plasma corticosterone concentration as body temperature (cloacal) rose from 28.2 to 40.7 degrees C in less than 6 h. However, the absolute increase in plasma B was small and much less than expected, despite the lethal stressor. Comparatively, the maximal B response to lethal heat stress was similar to plasma B concentrations obtained from breeding female turtles exposed to 8 h of capture stress. However, the maximal B response of breeding turtles exposed to heat and capture stressors was significantly less than the B response of nonbreeding adult female turtles subjected to an 8-h capture stressor. No negative correlations were observed between plasma T and plasma B, between plasma T and body temperature, between plasma P and plasma B, or between plasma P and body temperature. Our findings provide further evidence that reduced adrenocortical function operates in breeding green turtles in the presence of even the most pervasive of environmental stressors.

Adrenal Cortex↗
PubMed1999

Interactions between behavior and plasma steroids within the scramble mating system of the promiscuous green turtle, Chelonia mydas.

We measured plasma androgen (combined testosterone and 5alpha-dihydrotestosterone) (A) and corticosterone (B) in the promiscuous green turtle (Chelonia mydas) during courtship in the southern Great Barrier Reef. This study examined if reproductive behaviors and intermale aggression induced behavioral androgen and adrenocortical responses in reproductively active male and female green turtles. Associations between reproductive behavior and plasma steroids were investigated in green turtles across the population and within individuals. Levels across a range of both asocial and social behaviors were compared including (a) free swimming behavior; (b) initial courtship interactions; (c) mounted behavior (male and female turtles involved in copulatory activities); (d) intermale aggression (rival males that physically competed with another male turtle or mounted males recipient to these aggressive interactions); and (e) extensive courtship damage (male turtles that had accumulated excessive courtship damage from rival males). Behavioral androgen responses were detected in male turtles, in that plasma A was observed to increase with both attendant and mounted behavior. Male turtles who had been subjected to intermale aggression or who had accumulated severe courtship damage exhibited significantly lower plasma A than their respective controls. No pronounced adrenocortical response was observed after either intermale aggression or accumulation of extensive courtship damage. Female turtles exhibited a significant increase in plasma B during swimming versus mounted behavior, but no change in plasma A. We discuss our results in terms of how scramble polygamy might influence behavioral androgen interactions differently from more typical combative and territorial forms of male polygamy.

Aggression↗
PubMed2005

Do open-cycle hatcheries relying on tourism conserve sea turtles? Sri Lankan developments and economic-ecological considerations.

By combining economic analysis of markets with ecological parameters, this article considers the role that tourism-based sea turtle hatcheries (of an open-cycle type) can play in conserving populations of sea turtles. Background is provided on the nature and development of such hatcheries in Sri Lanka. The modeling facilitates the assessment of the impacts of turtle hatcheries on the conservation of sea turtles and enables the economic and ecological consequences of tourism, based on such hatcheries, to be better appreciated. The results demonstrate that sea turtle hatcheries serving tourists can make a positive contribution to sea turtle conservation, but that their conservation effectiveness depends on the way they are managed. Possible negative effects are also identified. Economic market models are combined with turtle population survival relationships to predict the conservation impact of turtle hatcheries and their consequence for the total economic value obtained from sea turtle populations.

Animals↗
PubMed1995

Seasonal- and temperature-dependent variation in CNS ascorbate and glutathione levels in anoxia-tolerant turtles.

We determined the ascorbic acid (ascorbate) and glutathione (GSH) contents of eight regions of the CNS from anoxia-tolerant turtles collected in summer and in winter. Ascorbate was of special interest because it is found in exceptionally high levels in the turtle CNS. The temperature-dependence of CNS ascorbate content was established by comparing levels in animals collected from two geographic zones with different average winter temperatures and in animals re-acclimated to different temperatures in the laboratory. The analytical method was liquid chromatography with electrochemical detection. Turtle ascorbate levels were 30-40% lower in animals acclimatized to winter (2 degrees C) than to summer (23 degrees C) in all regions of the CNS. Similarly, GSH levels were 20-30% lower in winter than in summer. Winter ascorbate levels were higher in turtles from Louisiana (19 degrees C) than in turtles acclimatized to winter in Wisconsin (2 degrees C). Summer and winter levels of ascorbate could be reversed by re-acclimating animals to cold (1 degree C) or warm (23 degrees C) temperatures for at least one week. CNS water content did not differ between cold- and warm-acclimated turtles. Taken together, the data indicated that ascorbate and GSH undergo significant seasonal variation and that the catalyst for change is environmental temperature. Steady-state ascorbate content showed a linear dependence on temperature, with a slope of 1.5% per degree C that was independent of CNS region. Lower levels of cerebral antioxidants in turtles exposed to colder temperatures were consistent with the decreased rate of cerebral metabolism that accompanies winter hibernation. Cerebral ascorbate and GSH levels in the turtle remained similar to or higher than those in mammals, even during winter, however. These findings support the notion that unique mechanisms of antioxidant regulation in the turtle contribute to their tolerance of the hypoxia-reoxygenation that characterizes diving behavior.

Animals↗
PubMed1983

Effect of chronic cold and submergence on blood oxygen transport in the turtle, Chrysemys picta.

Whole blood oxygen equilibrium curves (O2EC's) and related hematologic properties are reported for the turtle Chrysemys picta exposed to two experimental conditions. Summer turtles were maintained at 24 degrees C with free access to air; winter turtles were submerged for 4-12 wk in N2-bubbled water at 3 degrees C. Half-saturation Po2's at 3 degrees C for blood from summer and winter animals were 4.1 and 4.5 Torr, respectively. At 24 degrees C, summer and winter P50's were 20.2 and 22.7 Torr, respectively. The winter turtle P50 values were lower than predicted since prolonged submergence effected a severe metabolic acidosis; blood pH's for winter turtles were 0.65 pH unit lower than for summer animals at both temperatures. Cold submergence also had a profound influence on O2EC shape. Winter turtle curves exhibited high O2 affinity below P50 while they were distinctly right-shifted above 50% S. Winter animals also exhibited reduced CO2-Bohr coefficients (delta log Po2/delta pH) at 3 and 24 degrees C. Prolonged submergence did not affect the animal's isohemoglobin profile (demonstrated by isoelectric focusing) or [metHb]. The [ATP] and [DPG] in winter turtle red cells, however, decreased significantly; the ratio of organic phosphate ([ATP] + [DPG]) to Hb tetramer fell from 1.4 in summer animals to 0.5 in winter turtles. These findings suggest that the effect of chronic cold and prolonged submergence on turtle O2EC position and shape may result from reduction in RBC organic phosphates. Furthermore, these observed changes in blood oxygen transport may facilitate O2 loading during winter submergence via extrapulmonary gas exchange.

Acid-Base Equilibrium↗
PubMed2006

Fatty acid composition and lipid peroxidation of soft-shelled turtle, Pelodiscus sinensis, fed different dietary lipid sources.

Juvenile soft-shelled turtles (Pelodiscus sinensis) were fed 7 diets containing 8% of lard, soybean oil, olive oil, menhaden fish oil, or mixtures of 1 to 1 ratio of fish oil and lard, soybean oil, olive oil for 10 weeks. Growth and muscle proximate compositions of the turtles were not affected by different dietary treatments (p>0.05). Fatty acid profiles in muscle polar lipids, muscle non-polar lipids, and liver polar lipids reflected the fatty acid composition of dietary lipid source. Turtles fed diets containing fish oil generally contained significantly higher (p<0.05) proportion of highly unsaturated fatty acids (HUFA) in both polar and non-polar lipids of muscle and polar fraction of liver lipids than those fed other oils. Non-polar fraction of liver lipids from all groups of turtles contained less than 1% of HUFA. All turtles contained relatively high proportions of oleic acid in their lipids regardless of the dietary lipid source. Further, lipid peroxidation in both muscle tissue and liver microsomes of turtles fed fish oil as the sole lipid source was greater (p<0.05) than those fed fish oil-free diets. Turtles fed olive oil as the sole lipid source had the lowest lipid peroxidation rate among all dietary groups. The results indicate that dietary n-3 HUFA may not be crucial for optimal growth of soft-shelled turtles although they may be used for metabolic purpose. Further, high level of dietary HUFA not only increases the HUFA content in turtle tissues, but also enhances the susceptibility of these tissues to lipid peroxidation.

Animals↗