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PubMed2006

The relationship between gut contents and supercooling capacity in hatchling painted turtles (Chrysemys picta).

Painted turtles (Chrysemys picta) typically spend their first winter of life in a shallow, subterranean hibernaculum (the natal nest) where they seemingly withstand exposure to ice and cold by resisting freezing and becoming supercooled. However, turtles ingest soil and fragments of eggshell as they are hatching from their eggs, and the ingestate usually contains efficient nucleating agents that cause water to freeze at high subzero temperatures. Consequently, neonatal painted turtles have only a modest ability to undergo supercooling in the period immediately after hatching. We studied the limit for supercooling (SCP) in hatchlings that were acclimating to different thermal regimes and then related SCPs of the turtles to the amount of particulate matter in their gastrointestinal (GI) tract. Turtles that were transferred directly from 26 degrees C (the incubation temperature) to 2 degrees C did not purge soil from their gut, and SCPs for these animals remained near -4 degrees C for the 60 days of the study. Animals that were held at 26 degrees C for the duration of the experiment usually cleared soil from their GI tract within 24 days, but SCPs for these turtles were only slightly lower after 60 days than they were at the outset of the experiment. Hatchlings that were acclimating slowly to 2 degrees C cleared soil from their gut within 24 days and realized a modest reduction in their SCP. However, the limit of supercooling in the slowly acclimating animals continued to decline even after all particulate material had been removed from their GI tract, thereby indicating that factors intrinsic to the nucleating agents themselves also may have been involved in the acclimation of hatchlings to low temperature. The lowest SCPs for turtles that were acclimating slowly to 2 degrees C were similar to SCPs recorded in an earlier study of animals taken from natural nests in late autumn, so the current findings affirm the importance of seasonally declining temperatures in preparing animals in the field to withstand conditions that they will encounter during winter.

Acclimatization↗

PubMed2004

Interplay between plasma hormone profiles, sex and body condition in immature hawksbill turtles (Eretmochelys imbricata) subjected to a capture stress protocol.

We investigated plasma hormone profiles of corticosterone and testosterone in immature hawksbill turtles (Eretmochelys imbricata) in response to a capture stress protocol. Further, we examined whether sex and body condition were covariates associated with variation in the adrenocortical response of immature turtles. Hawksbill turtles responded to the capture stress protocol by significantly increasing plasma levels of corticosterone over a 5 h period. There was no significant sex difference in the corticosterone stress response of immature turtles. Plasma testosterone profiles, while significantly different between the sexes, did not exhibit a significant change during the 5 h capture stress protocol. An index of body condition was not significantly associated with a turtle's capacity to produce plasma corticosterone both prior to and during exposure to the capture stress protocol. In summary, while immature hawksbill turtles exhibited an adrenocortical response to a capture stress protocol, neither their sex nor body condition was responsible for variation in endocrine responses. This lack of interaction between the adrenocortical response and these internal factors suggests that the inactive reproductive- and the current energetic- status of these immature turtles are important factors that could influence plasma hormone profiles during stress.

Age Factors↗

PubMed2005

Metabolic response to feeding in the Chinese striped-necked turtle, Ocadia sinensis.

We measured oxygen consumption in juvenile Chinese striped-necked turtles (Ocadia sinensis) after they ingested food, either as a single meal or as double meals, to examine the influence of meal type and feeding frequency on specific dynamic action (SDA). Temporal variation in oxygen consumption after feeding was evident in the ingesting turtles but not in the unfed control turtles. In the single-meal experiment, the peak metabolic rate and the integrated SDA response (the whole energetic cost for the processes of digestion) both did not differ between turtles ingesting mealworms and shrimps when the influence of variation in ingested energy was removed, and the time to reach peak metabolic rate was not affected by meal type and the amount of food ingested. Turtles in the double-meal experiment ingested more energy and hence had a prolonged duration of SDA response than did those in the single-meal experiment, but the integrated SDA response did not differ between both experimental treatments when the influence of variation in ingested energy was removed. Our results show that meal type and feeding frequency have important consequences on the SDA response of juvenile O. sinensis. As the integrated SDA response remained remarkably constant either between turtles ingesting different food or between turtles ingesting the same food but at different frequencies when the influence of variation in ingested energy was removed, we therefore conclude that the energetic cost associated with ingestion is primarily determined by energy content of food ingested in juvenile O. sinensis.

Animal Nutritional Physiological Phenomena↗

PubMed1997

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. Our aim in this study was to compare myocardial PDE profiles between the highly hypoxia tolerant western painted turtle (Chrysemys picta bellii) and the relatively hypoxia sensitive softshelled turtle (Trionyx spinifer) in order to begin to rest the hypothesis that high constitutive levels of cytosolic PDEs may play a role in conferring hypoxia and ischemia tolerance on the myocardium. We also collected 31P-NMR spectra of PCA extracts of tissue from these species and from Kemp's ridley sea turtles (Lepidochelys kempi), as well as spectra from isolated hearts and PCA extracts of red-eared sliders (Trachemys [formerly Pseudemys] scripta]). Total NMR visible phosphodiesters make up 24 +/- 8.6% of the total NMR visible phosphorus in Chrysemys hearts, 20.7 +/- 5.9% in Trachemys hearts, but only 12.2 +/- 5.1% in Trionyx hearts (P < 0.05). We have identified three distinct PDEs in turtle hearts: glycerophosphorylcholine (GPC); glycerophosphorylethanolamine (GPE); and serine ethanolamine phosphodiester (SEP). SEP is the dominant compound in Chrysemys and Trachemys (79.3 +/- 10.2% and 84.7 +/- 3.7% of total PDE, respectively), while GPC is most abundant in Trionyx (74.0 +/- 4.3% of total PDE) and Lepidochelys (not quantitated). The function of this class of compounds is unclear but it has been suggested that cytosolic PDEs may function as lysophospholipase inhibitors, a role that would decrease the rate of membrane phospholipid turnover. Our comparative data suggest that cytosolic PDEs could play a role in phospholipid sparing during anoxic or ischemic stress in turtles but a direct test of this hypothesis awaits future experimentation.

Animals↗

PubMed2001

Hypotheses of aging in a long-lived vertebrate, Blanding's turtle (Emydoidea blandingii).

For 35 of the past 47 years, Blanding's turtles were studied on the University of Michigan's E.S. George Reserve in southeastern Michigan. Blanding's turtle is one of the longest-lived emydid turtles with individuals reaching ages greater than 75 years. We compared body sizes, reproductive traits and survival of Young, Middle, and Oldest age groups of Blanding's turtles to test predictions from two contrasting hypotheses of aging. The relative reproductive rate hypothesis predicts traits that increase the reproductive output or survival rates of older compared to younger individuals, whereas the senescence hypothesis predicts a reduction in reproductive output or survival in older versus younger individuals. Body size did not increase with age among groups; therefore, indeterminate growth was not a mechanism for increased reproductive output of the oldest individuals. Survivorship, reproductive frequency and size-adjusted mean clutch size were all higher in the Oldest age group compared to the younger age groups. Nest predation rate was highest in the Young age group compared to either group of older turtles. In nests that survived predation, the proportion of nests that failed entirely due to developmental problems was lowest in the Young, intermediate in the Middle, and highest in the Oldest age group. Successful nests produced similar numbers of hatchlings and similar sized hatchlings in all three age groups. Traits such as egg and offspring size, and offspring produced per nest did not support either the relative reproductive rate or the senescence hypothesis of aging. Increased embryo mortality in nests of older females compared to younger turtles supports predictions from the senescence hypothesis. Three traits; increased clutch size, reproductive frequency, and survivorship of individuals in the Oldest age group compared to younger turtles support the relative reproductive rate hypothesis for evolution of longevity.

Aging↗

PubMed2003

The eastern box turtle at the Patuxent Wildlife Research Center 1940s to the present: another view.

Several long-term mark recapture studies have been conducted on box turtles (Terrapene c. carolina) providing valuable information on life span, basic demography, home range, and apparent effects of environmental changes on box turtle survival. One of the longest studied populations was first marked in 1942 on the Patuxent Wildlife Research Center in Maryland, and has been surveyed every 10 years until 1995. The age structure and gender ratio of these turtles in the field may support differential habitat use and survival estimates. A few of the turtles first marked during the 1945 study are still observed throughout the Center. Data collected from turtles marked in the more upland habitats during 1985-2002 indicate a younger age class distribution than that observed in the more protected biota of the bottomland floodplain study area. Extrapolating ages of turtles described in data collected throughout the long-term study, it was estimated that turtles, both males and females, can show reproduction-intent behaviors at ages greater than 54 years old. It is suggested that count data collection be continued on a more frequent cycle, extending over a larger part of the Center.

Aging↗

PubMed2003

Is turtle longevity linked to enhanced mechanisms for surviving brain anoxia and reoxygenation?

We suggest that the processes that protect the turtle brain against anoxia and subsequent reoxygenation might also contribute to turtle longevity since many of them are linked to age related neurodegeneration. In the turtle the mechanisms for conserving ion channel function are particularly robust. The anoxic turtle brain avoids excitatory neurotransmitter toxicity by maintaining a balance between dopamine and glutamate-release and still active uptake mechanisms. In the anoxic turtle brain the inhibitory tone is strengthened through a sustained rise in extracellular GABA, and a corresponding increase in the density of GABA(A) receptors. The turtle has enhanced mechanisms that protect against the formation of ROS and mechanisms to protect from ROS damage. As many of these may be selectively activated during anoxia and recovery, the turtle could serve as a useful model to identify and investigate mechanisms for activating key protection and rescue mechanisms implicated in aging.

Adaptation, Physiological↗

PubMed2001

The physiology of hibernation in common map turtles (Graptemys geographica).

Map turtles from Wisconsin were submerged at 3 degrees C in normoxic and anoxic water to simulate extremes of potential respiratory microenvironments while hibernating under ice. In predive turtles, 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 body mass were determined, and plasma [HCO3-] was calculated. Turtles in anoxic water developed a severe metabolic acidosis, accumulating lactate from a predive value of 1.7 to 116 mmol/l at 50 days, associated with a fall in pH from 8.010 to 7.128. To buffer lactate increase, total calcium and magnesium rose from 3.5 and 2.0 to 25.7 and 7.6 mmol/l, respectively. Plasma [HCO3-] was titrated from 44.7 to 4.3 mmol/l in turtles in anoxic water. Turtles in normoxic water had only minor disturbances of their acid-base status and ionic statuses; there was a marked increase in hematocrit from 31.1 to 51.9%. This study and field studies suggest that map turtles have an obligatory requirement for a hibernaculum that provides well-oxygenated water (e.g. rivers and large lakes rather than small ponds and swamps) and that this requirement is a major factor in determining their microdistribution.

Acid-Base Equilibrium↗

PubMedDate not supplied

Comparison between oogenesis and related ovarian structures in a reptile, Pseudemys scripta elegans (turtle) and in a bird Coturnix coturnix japonica (quail).

The aspect of the oogonia during their premitotic DNA synthesis and of the premeiocytes during their premeiotic DNA synthesis was studied in turtles by autoradiography, after injection of 3H-thymidine. As in the adult laying quail, the intrafollicular oocytes of the adult turtle go through three successive stages: prelampbrush, lampbrush and postlampbrush. During the prelampbrush and lampbrush stage two kinds of nucleoli exist: peripheral and central. In contrast to avian yolk, during its final rapid growth, no polyhedric protein yolk units were found in turtle yolk. As in the yellow yolk of quail, highly osmiophilic alcohol insoluble satellite yolk (egg oil) accumulates between the protein globular yolk of Pseudemys. Turtle yolk globules increase in volume by fusion. The penetration of peripherally assembled yolk in the turtle germinal disc is analogous to what we have described in the quail. Also in postlampbrush germinal discs subcortical ooplasmic organelles are present. Below the turtle germinal disc no structure comparable to the avian nucleus of Pander could be observed. No pyriform cells (as in squamate reptiles) and no pyriform-like cells (as in birds: Callebaut, 1991 b) were found in the chelonian ovarian granulosa layer. We could not demonstrate functional lacunoperitoneal communications via openings in the hilus ovarii of the turtle as is the case in birds.

Animals↗

PubMedDate not supplied

Embryonic temperature affects metabolic compensation and thyroid hormones in hatchling snapping turtles.

Temperature acclimation of adult vertebrates typically induces changes in metabolic physiology. During early development, such metabolic compensation might have profound consequences, yet acclimation of metabolism is little studied in early life stages. We measured the effect of egg incubation temperature on resting metabolic rate (RMR) and blood thyroid hormone levels of hatchling snapping turtles (Chelydra serpentina). Like many reptiles, snapping turtles have temperature-dependent sex determination (TSD), in which embryonic temperature determines sex. Therefore, we designed the experiments to separately measure effects of temperature and of sex on the response variables. We incubated eggs in the laboratory at 21. 5 degrees, 24.5 degrees, 27.5 degrees, and 30.5 degrees C, producing both sexes, all males, both sexes, and all females, respectively. Hatchling RMR, when measured at a common temperature (either 25 degrees or 31 degrees C), was negatively correlated with egg temperature in both males and females, such that RMR of turtles from 21.5 degrees C-incubated eggs averaged 160% that of turtles from 30.5 degrees C-incubated eggs. These results indicate that egg temperatures induced positive metabolic compensation in both sexes. Thyroid hormone levels of hatchlings showed similar correlations with egg temperature; thyroxine level of turtles from 21.5 degrees C-incubated eggs averaged 220% that of turtles from 30.5 degrees C-incubated eggs. To examine the possibility that thyroid hormones contribute to positive metabolic compensation, we added triiodothyronine to eggs during mid-incubation. RMR of hatchlings from these treated eggs averaged 131% that of controls, consistent with the previous possibility. Moreover, the effects of embryonic temperature on metabolic physiology, in combination with effects on sex, can result in differences in RMR and thyroid hormone levels between male and female hatchling turtles. Such differences may be important to the ecology and evolution of TSD.

Adaptation, Physiological↗

PubMedDate not supplied

Aquatic and terrestrial locomotory energetics in a toad and a turtle: a search for generalisations among ectotherms.

Murray short-necked turtles were trained to walk on a motorised treadmill and to swim in a recirculating flume. Through filmed records, the frequency of limb movement and the time that thrust was directed against the substrate were measured. The animals wore masks when walking and accessed air when swimming from a ventilated capsule placed on top of the water surface. Measurement of the exhalant O(2) and CO(2) levels from these devices enabled the measurement of metabolic rates. Equivalent data were obtained from swimming and hopping cane toads, although repeatable measures of limb frequency and contact times were not obtained due to the intermittent form of locomotion in this species. Comparing the cost of transport, the energy required to transport a mass of animal over a unit distance, with other animals showed that toads do not have a cheap form of terrestrial locomotion, but turtles do; turtles use half the cost predicted from their body mass. This economy of locomotion is consistent with what is known about turtle muscle, the mechanics of their gait, and the extremely long contact time for a limb with the substrate. Swimming in toads is energetically expensive, whereas turtles, on the basis of mass, use about the same energy to transport a unit mass as an equivalent-size fish. The data were compared with the predictions of the Kram-Taylor hypothesis for locomotory scaling, and walking turtles were found to provide a numerical fit. The data show that both terrestrial and aquatic locomotory energetics in toads are generally higher than predictions on the basis of mass, whereas in turtles they are lower.

Animals↗

PubMed2004

Sister group relationship of turtles to the bird-crocodilian clade revealed by nuclear DNA-coded proteins.

The phylogenetic position of turtles is a currently controversial issue. Recent molecular studies rejected a traditional view that turtles are basal living reptiles (Hedges, S. B., and L. L. Poling. 1999. A molecular phylogeny. Science 83:998-1001; Kumazawa, Y., and M. Nishida. 1999. Complete mitochondrial DNA sequences of the green turtle and blue-tailed mole skink, statistical evidence for archosaurian affinity of turtles. Mol. Biol. Evol. 16:784-792). Instead, these studies grouped turtles with birds and crocodiles. The relationship among turtles, birds, and crocodiles remained unclear to date. To resolve this issue, we have cloned and sequenced two nuclear genes encoding the catalytic subunit of DNA polymerase alpha and glycinamide ribonucleotide synthetase-aminoimidazole ribonucleotide synthetase-glycinamide ribonucleotide formyltransferase from amniotes and an amphibian. The amino acid sequences of these proteins were subjected to a phylogenetic analysis based on the maximum likelihood method. The resulting tree showed that turtles are the sister group to a monophyletic cluster of archosaurs (birds and crocodiles). All other possible tree topologies were significantly rejected.

Alligators and Crocodiles↗

PubMed2005

Behaviour of leatherback sea turtles, Dermochelys coriacea, during the migratory cycle.

Leatherback sea turtles, Dermochelys coriacea, undertake broad oceanic movements. While satellite telemetry has been used to investigate the post-nesting behaviour of female turtles tagged on tropical nesting beaches, long-term behavioural patterns of turtles of different sexes and sizes have not been described. Here we investigate behaviour for 25 subadult and adult male and female turtles satellite-tagged in temperate waters off Nova Scotia, Canada. Although sex and reproductive condition contributed to variation in migratory patterns, the migratory cycle of all turtles included movement between temperate and tropical waters. Marked changes in rates of travel, and diving and surfacing behaviour, accompanied southward movement away from northern foraging areas. As turtles approached higher latitudes the following spring and summer, they assumed behaviours consistent with regular foraging activity and eventually settled in coastal areas off Canada and the northeastern USA. Behavioural patterns corresponding to various phases of the migratory cycle were consistent across multiple animals and were repeated within individuals that completed return movements to northern waters. We consider the potential biological significance of these patterns, including how turtle behaviour relates to predator avoidance, thermoregulation and prey distribution.

Animal Migration↗

PubMed2005

Genomic variation of the fibropapilloma-associated marine turtle herpesvirus across seven geographic areas and three host species.

Fibropapillomatosis (FP) of marine turtles is an emerging neoplastic disease associated with infection by a novel turtle herpesvirus, fibropapilloma-associated turtle herpesvirus (FPTHV). This report presents 23 kb of the genome of an FPTHV infecting a Hawaiian green turtle (Chelonia mydas). By sequence homology, the open reading frames in this contig correspond to herpes simplex virus genes UL23 through UL36. The order, orientation, and homology of these putative genes indicate that FPTHV is a member of the Alphaherpesvirinae. The UL27-, UL30-, and UL34-homologous open reading frames from FPTHVs infecting nine FP-affected marine turtles from seven geographic areas and three turtle species (C. mydas, Caretta caretta, and Lepidochelys olivacea) were compared. A high degree of nucleotide sequence conservation was found among these virus variants. However, geographic variations were also found: the FPTHVs examined here form four groups, corresponding to the Atlantic Ocean, West pacific, mid-Pacific, and east Pacific. Our results indicate that FPTHV was established in marine turtle populations prior to the emergence of FP as it is currently known.

Amino Acid Sequence↗

PubMed1983

Active electrogenic mechanisms for alkali and acid transport in turtle bladders.

Immediately after mounting in the Ussing chamber between choline bicarbonate Ringer solutions devoid of exogenous Na and Cl, the serosal fluid is electronegative to the luminal fluid in bladders from postabsorptive and acidotic turtles; and electropositive in bladders from alkalotic turtles. In bladders from postprandial turtles, the electrical orientation, initially serosal positive, reverses to serosal negative. Serosal additions of 3-isobutyl-1-methylxanthine (IBMX) and adenosine 3',5'-cyclic monophosphate (cAMP) produce no changes in the negative short-circuiting current (Isc) of acidotic turtles but induce large positively-directed increases of Isc in bladders from other turtle groups. With IBMX and cAMP in the (HCO3 + CO2)-rich serosal fluid at pH 7.2 and with luminal pH maintained at 4.0-5.0, the rate at which titratable alkali enters the luminal fluid is electrochemically equal to the positive Isc; and this increased positive Isc is the same as that in the absence of transepithelial gradients. The effects of acetazolamide and 4-acetamido-4-isothiocyanostilbene-2,2'-disulfonic acid on positive and negative Isc are presented. It is concluded that isolated bladders from alkalotic, postprandial or postabsorptive turtles, but not those from acidotic turtles, possess an active electrogenic mechanism for a Na-independent Cl-independent secretion of bicarbonate. This transport process is accelerated by phosphodiesterase inhibitors (IBMX) and cAMP or its eight substituted derivatives.

1-Methyl-3-isobutylxanthine↗

PubMed1983

Arterial baroreceptor reflex control of heart rate in two species of turtle.

Attempts were made to stimulate an arterial baroreceptor reflex in anesthetized and conscious pond turtles. In turtles anesthetized with either alpha-chloralose or pentobarbital, occlusion of the ascending or descending aortas produced no reflex heart rate (HR) changes. In pentobarbital-anesthetized turtles, direct electrical or mechanical stimulation of potential baroreceptor sites along the central aortic arches and carotid arteries produced no significant changes in either HR or blood pressure (BP). Occlusion of the common carotid arteries also produced no HR or BP changes. Intravenously administered nitroglycerin lowered BP but caused no reflex tachycardia in anesthetized turtles. Phenylephrine and angiotensin elevated BP in the anesthetized turtle but caused no reflex bradycardia. In conscious turtles phenylephrine increased BP and nitroglycerin decreased BP. Neither response produced a statistically significant HR change, although HR tended to decrease transiently with phenylephrine and increase with nitroglycerin. These HR changes were abolished by atropine. Rapid intra-arterial infusion of 6% dextran transiently raised BP but caused no reflex bradycardia. These experiments suggest that cardiovascular regulation in the turtle is accomplished without a major contribution from arterial baroreceptor reflexes.

Anesthesia, General↗

PubMed1990

Extracellular pH and suppression of electrical activity during anoxia in turtle and rat brain.

To evaluate the contribution of extracellular H+ activity toward depression of brain electrical activity during anoxia, extracellular pH (pHe) and field potentials were measured in turtle and rat olfactory bulbs with ion-selective microelectrodes. This study tests the hypothesis that unique regulation of pHe contributes to the remarkable tolerance of turtle brain to prolonged anoxia. Hypercapnea (20% CO2 ventilation) depressed olfactory bulb evoked potentials 25-30% in both rat and turtle. During anoxia, evoked potentials were completely abolished within 1 min in rat olfactory bulb but decreased to only 40% of control after 4 h in the turtle despite similar changes in brain pHe. Anoxia-induced acidification of turtle brain was exacerbated by hypercapnea and was attenuated by hypocapnea or by hypocapnea plus intravenous infusion of sodium bicarbonate. However, these manipulations of pHe during anoxia in turtle brain had little effect on depression of evoked potentials. We conclude that energy failure, rather than extracellular acidification, is the major contributor toward suppression of electrical activity in mammalian brain and that preservation of energy balance, rather than unique pH regulation, is responsible for protection of turtle brain during anoxia.

Action Potentials↗

PubMed2000

Expression of heat shock proteins in turtle and mammal hearts: relationship to anoxia tolerance.

Heat shock proteins (HSPs) may play a cardioprotective role during hypoxia or ischemia. We hypothesized that cardiac tissue from hypoxia-tolerant animals might have high levels of specific HSPs. We measured myocardial HSP60 and HSP72/73 in painted and softshell turtles during normoxia and anoxia (12 h) and after recovery (12 or 24 h). We also measured myocardial HSPs in normoxic rats and rabbits. During normoxia, hearts from the most highly anoxia-tolerant species, the painted turtle, expressed the highest levels of HSP60 (22.6+/-2.0 mg/g total protein) followed by softshells (11.5+/-0.8 mg/g), rabbits (6.8+/-0.9 mg/g), and rats (4.5+/-0.5 mg/g). HSP72/73 levels, however, were not significantly different. HSP60 levels in hearts from both painted and softshell turtles did not deviate significantly from control values after either 12 h of anoxia or 12 or 24 h of recovery. The pattern of changes observed in HSP72/73 was quite different in the two turtle species. In painted turtles anoxia induced a significant increase in myocardial HSP72/73 (from 2.8+/-0.1 mg/g normoxic to 3.9+/-0.2 mg/g anoxic, P<0.05). By 12 h of recovery, HSP72/73 had returned to control levels (2.7+/-0.1 mg/g) and remained there through 24 h (2.6+/-0.2 mg/g). In softshell turtles, HSP72/73 decreased significantly after 12 h of anoxia (from 2.4+/-0.4 mg/g normoxic to 1.3+/-0.2 mg/g anoxic, P<0.05). HSP72/73 levels were still slightly below control after 12 h of recovery (2.1+/-0.1 mg/g) and then rose to significantly above control after 24 h of recovery (4.1+/-0.7 mg/g, P<0.05). We also conclude that anoxia-tolerant and anoxia-sensitive turtles exhibit different patterns of myocardial HSP changes during anoxia and recovery. Whether these changes correlate with their relative degrees of anoxia tolerance remains to be determined.

Air↗