Seasonal changes of total lipids in the turtle Sternotherus odoratus

McPherson, R; Marion, Ken R.

doi:10.1016/0300-9629(82)90372-3

Cited by 14 publications

(10 citation statements)

References 31 publications

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“…Many turtles do not have discrete abdominal fat bodies, but instead have many small fat deposits throughout the abdominal cavity (Pond, ; Ho et al., ; McPherson & Marion, ; Henen, ). However, Rhen & Lang () describe fat bodies in the inguinal region and abdomen of snapping turtles ( Chelydra serpentina ).…”

Section: Lipid Structure and Storagementioning

confidence: 99%

“…Often, however, the liver increases in mass and/or lipid content, at least at the beginning of vitellogenesis (Dessauer & Fox, ; Derickson, ; Lin, ; Raheem & Dehlawi, ). For example, in the stinkpot turtle Sternotherus odoratus , carcass lipids (presumably lipids in diffuse adipose deposits) decreased in August while liver lipid content increased, just prior to vitellogenesis (McPherson & Marion, ). The authors concluded that lipids in adipose tissue were transported to the liver to be used in the synthesis of yolk precursors, and that the liver did not represent a storage site for lipids so much as a site of synthesis and degradation (McPherson & Marion, ).…”

Section: Lipid Structure and Storagementioning

confidence: 99%

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The physiology of lipid storage and use in reptiles

Price

2016

Biological Reviews

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Lipid metabolism is central to understanding whole-animal energetics. Reptiles store most excess energy in lipid form, mobilise those lipids when needed to meet energetic demands, and invest lipids in eggs to provide the primary source of energy to developing embryos. Here, I review the mechanisms by which non-avian reptiles store, transport, and use lipids. Many aspects of lipid absorption, transport, and storage appear to be similar to birds, including the hepatic synthesis of lipids from glucose substrates, the transport of triglycerides in lipoproteins, and the storage of lipids in adipose tissue, although adipose tissue in non-avian reptiles is usually concentrated in abdominal fat bodies or the tail. Seasonal changes in fat stores suggest that lipid storage is primarily for reproduction in most species, rather than for maintenance during aphagic periods. The effects of fasting on plasma lipid metabolites can differ from mammals and birds due to the ability of non-avian reptiles to reduce their metabolism drastically during extended fasts. The effect of fasting on levels of plasma ketones is species specific: β-hydroxybutyrate concentration may rise or fall during fasting. I also describe the process by which the bulk of lipids are deposited into oocytes during vitellogenesis. Although this process is sometimes ascribed to vitellogenin-based transport in reptiles, the majority of lipid deposition occurs via triglycerides packaged in very-low-density lipoproteins (VLDLs), based on physiological, histological, biochemical, comparative, and genomic evidence. I also discuss the evidence for non-avian reptiles using 'yolk-targeted' VLDLs during vitellogenesis. The major physiological states - feeding, fasting, and vitellogenesis - have different effects on plasma lipid metabolites, and I discuss the possibilities and potential problems of using plasma metabolites to diagnose feeding condition in non-avian reptiles.

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Section: Lipid Structure and Storagementioning

confidence: 99%

Section: Lipid Structure and Storagementioning

confidence: 99%

The physiology of lipid storage and use in reptiles

Price

2016

Biological Reviews

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“…Most of the catabolized body E nl was probably in the form of protein because (1) captive desert tortoises experience negative nitrogen balance on a diet of dry Schismus barbatus (Meienberger et al 1993); (2) garter snakes catabolize body protein to fuel metabolism (Aleksiuk and Stewart 1971); (3) urinary nitrogen excretion in reptiles (McDonald 1976) indicates that protein is an energy source; (4) glycogen stores in vertebrates usually represent small energy reserves relative to visceral and skeletal protein stores (Lehninger 1975, Harlow andBuskirk 1991); (5) many reptiles use lipids (not glycogen) as their large energy stores (Aleksiuk and Stewart 1971, Derickson 1976, McPherson and Marion 1982, and Long 1985; (6) at least one vertebrate (the rat) can selectively catabolize protein from specific tissues (see Thompson et al 1993); and (7) female tortoises probably were absorbing carbohydrates from their diet. There is very little evidence that glycogen is a major energy store in reptiles (Derickson 1976), but few reptilian studies have measured glycogen directly (Rapatz andMusacchia 1957, Emerson 1967).…”

Section: Seasonal Energy Budgetsmentioning

confidence: 99%

SEASONAL AND ANNUAL ENERGY BUDGETS OF FEMALE DESERT TORTOISES (GOPHERUS AGASSIZII)

Henen

1997

Ecology

145

130

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How do female desert tortoises (Gopherus agassizii) reproduce every year despite variability in winter rainfall and food availability? To answer this question, I measured energy budgets of individual female desert tortoises from July 1987 to July 1989. Females produced eggs in years with low levels of winter annual plants by relaxing their control of energy and water homeostasis. They tolerated large deficits and surpluses in their body dry‐matter composition (both nonlipid and lipid) on a seasonal, annual, and longer time scale. They could increase body energy content (lipid and nonlipid energy) before winter and use this reserve (especially nonlipid energy) the following spring to produce eggs. Females used high‐protein foods and rainwater, when available, to achieve energy surpluses that helped them survive periods of low resource availability (e.g., during hibernation and droughts). Adjusting seasonal and annual field metabolic rates (FMR) and food requirements to levels of food availability, they still managed to produce eggs, even in a drought year. Egg production in 1988 (mean ± 1 sd: 3.56 ± 1.94 eggs, N = 9) did not differ from that in 1989 (3.00 ± 2.69 eggs, N = 9); both were lower than during 1983–1987 (6.75 ± 3.05 eggs, N = 100). Energy per se did not limit egg production in 1988 and 1989, but the availability of nonlipid energy (probably protein) limited egg production in 1988 and was limiting in spring 1989. Yet, water was the primary resource limiting egg production in 1989. Females forgoing egg production in 1989 accumulated body nonlipid energy and lost less total body water than did females producing eggs. Females that produced eggs in 1989 forfeited body nonlipid energy. In 1988 and 1989, the paucity of new annual plants in spring contributed to a lower egg production. The amount of annuals that germinate in summer can affect egg production, because females stored nonlipid energy during summer 1988 when eating these annuals, and allocated this energy to eggs in the following spring (1989). Tortoises stored lipids during summer when consuming dry annuals. These lipids are critical for surviving the winter, but females forfeited body water and nonlipid dry matter to digest the dry annuals. Reproductive effort (RE) was higher during the drought year (July 1988–July 1989: RE = 26.1%) than during the wetter year (July 1987–July 1988: RE = 13.0%) because tortoises reduced FMR by 70–90% in 1989. Compared to two other chelonians, RE of desert tortoises was consistent with the K‐selected trend of lower RE for larger, long‐lived, and late‐maturing species. Forfeiting body condition to produce only a few eggs, even under a great environmental stress, was consistent with a life history strategy called bet hedging.

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“…fat bodies), as d o other reptiles, instead accumulating fat in small pads throughout the body (McPherson & Marion, 1982). In 1976, Derickson noted that little work had been done on lipid storage and utilization in turtles, and this largely remains the case.…”

Section: ( a ) Energeticsmentioning

confidence: 99%

“…Turtles do not have specific storage organs for lipids (e.g. fat bodies), as d o other reptiles, instead accumulating fat in small pads throughout the body (McPherson & Marion, 1982). Brisbin (1972), working with the terrestrial emydid Terrapene carolina in Georgia, found that even after 5 months of winter dormancy, total body fat was not reduced.…”

Section: ( a ) Energeticsmentioning

confidence: 99%

Ecology and Physiology of Hibernation and Overwintering Among Freshwater Fishes, Turtles, and Snakes

1989

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Summary 1. Freshwater fishes are the most northerly of freshwater ectotherms, followed by frogs. North American freshwater snakes, turtles, and salamanders do not range farther north than southernmost Canada. 2. Freezing and desiccation are the main challenges during terrestrial hibernation of ectotherms. Oxygen depletion, water balance, and ionic balance are the major problems for air breathing ectotherms that hibernate underwater. 3. The importance of accumulation of energy stores for overwintering among fishes depends upon the length and severity of the winters, whether or not there is springtime reproduction, body size, latitude, and the availability and use of food during overwintering. 4. Fishes can decrease energy demands during the winter by reductions in activity, metabolic depression, and entrance in semi‐torpidity. 5. Adaptations for coping with hypoxia and anoxia among overwintering freshwater fishes may include metabolic depression, a decrease in blood O2 affinity, microhabitat selection, air breathing, short‐distance migration, biochemical modifications aimed at adjusting glycolytic rates, and alcoholic fermentation. 6. Freshwater turtles have a worldwide northern limit of approximately 50° N, which means that some species spend about half of their lives hibernating. 7. Aquatic turtles normally hibernate underwater, although occasionally they hibernate on land. In water they usually hibernate in a hypoxic or anoxic (mud) environment and in relatively shallow water. Wintertime movements of unknown frequency occur in some species. 8. The hatchlings of many turtle species can overwinter in the nest. Among northern species this behaviour is most common among painted turtles, whose hatchlings can withstand freezing. 9. Mortality among adult turtles is probably highest during the hibernation cycle. 10. Temperature appears to the most important cue for entry and exit from hibernation among freshwater turtles. 11. Little is known of the energetics of overwintering turtles. Energy stores for overwintering may be more important at lower latitudes than at higher ones, due to the higher metabolic rates of overwintering, but non‐feeding, southern turtles. 12. The ability of turtles to tolerate submergence is a function of temperature, degree of water oxygenation, latitude of origin, efficacy of extrapulmonary respiratory pathways, and metabolic rate. 13. For turtles that hibernate in an anoxic hibernaculum, and for those without sufficient extrapulmonary uptake of O2 to allow metabolism to be completely aerobic, the most important physiological perturbation is an acidosis developed from a continuing production of lactate. If sufficient O2 can be obtained, the most likely factors limiting hibernation time are water balance and ion balance. 14. Mechanisms of turtles for coping with acidosis include metabolic depression, integumental CO2 loss, bicarbonate buffering, and changes in ion concentrations that minimize the decrease in SID (strong ion difference). The most important among the latter are a decrease in plas...

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Seasonal changes of total lipids in the turtle Sternotherus odoratus

Cited by 14 publications

References 31 publications

The physiology of lipid storage and use in reptiles

The physiology of lipid storage and use in reptiles

SEASONAL AND ANNUAL ENERGY BUDGETS OF FEMALE DESERT TORTOISES (GOPHERUS AGASSIZII)

Ecology and Physiology of Hibernation and Overwintering Among Freshwater Fishes, Turtles, and Snakes

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