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PubMed2006

Temporal and spatial variation of terpenoids in eastern hemlock (Tsuga canadensis) in relation to feeding by Adelges tsugae.

The terpenoid content of eastern hemlock (Tsuga canadensis) foliage was measured over an annual cycle of development from bud opening, shoot elongation, shoot maturation, to bud-break at the start of the next growing season. The objective was to determine if variation in terpenoid composition is linked with spatial and temporal feeding preferences of the hemlock woolly adelgid (HWA; Adelges tsugae). The HWA has two periods of feeding over the course of 1 yr spanning two complete generations. There are two periods of feeding separated by a nonfeeding period where the adelgid estivates. HWA prefers to feed on mature, rather than young, expanding tissue. Feeding occurs in the leaf cushion at the base of the needle. The needle is the only tissue in hemlock with resin canals that store terpenoids. The needle and leaf cushion of both the current and previous years' growth were analyzed separately over a 1-yr period to examine the variation of terpenoid composition in space and time. Terpenoids were quantified by using headspace solid-phase microextraction/gas chromatography/mass spectrometry (SPME/GC/MS). New growth needles and leaf cushions do not resemble the previous year's growth either visually or in chemical composition until October/November, when the adelgid breaks estivation and begins feeding. Nearly all of the 23 terpenoids present exceeding 0.1% varied significantly either temporally or spatially, usually with complex interactions. Ordination and factor analysis revealed that terpenoids are less variable in mature leaf cushions than in young tissue. By entering a nonfeeding diapause during the late spring and summer, HWA avoids the unstable, variable levels of terpenoids in the immature leaf cushion and needles.

Animals↗
PubMed2002

Animal response to drastic changes in oxygen availability and physiological oxidative stress.

Oxygen is essential for most life forms, but it is also inherently toxic due to its biotransformation into reactive oxygen species (ROS). In fact, the development of many animal and plant pathological conditions, as well as natural aging, is associated with excessive ROS production and/or decreased antioxidant capacity. However, a number of animal species are able to tolerate, under natural conditions, situations posing a large potential for oxidative stress. Situations range from anoxia in fish, frogs and turtles, to severe hypoxia in organs of freeze-tolerant snakes, frogs and insect larvae, or diving seals and turtles, and mild hypoxia in organs of dehydrated frogs and toads or estivating snails. All situations are reminiscent of ischemia/reperfusion events that are highly damaging to most mammals and birds. This article reviews the responses of anoxia/hypoxia-tolerant animals when subjected to environmental and metabolic stresses leading to oxygen limitation. Abrupt changes in metabolic rate in ground squirrels arousing from hibernation, as well as snails arousing from estivation, may also set up a condition of increased ROS formation. Comparing the responses from these diverse animals, certain patterns emerge. The most commonly observed response is an enhancement of the antioxidant defense. The increase in the baseline activity of key antioxidant enzymes, as well as 'secondary' enzymatic defenses, and/or glutathione levels in preparation for a putative oxidative stressful situation arising from tissue reoxygenation seem to be the preferred evolutionary adaptation. Increasing the overall antioxidant capacity during anoxia/hypoxia is of relevance for species such as garter snakes (Thamnophis sirtalis parietalis) and wood fogs (Rana sylvatica), while diving freshwater turtles (Trachemys scripta elegans) appear to rely mainly upon high constitutive activities of antioxidant enzymes to deal with oxidative stress arising during tissue reoxygenation. The possibility that some animal species might control post-anoxic ROS generation cannot be excluded.

Adaptation, Physiological↗
PubMed1997

Cardiovascular, respiratory and metabolic responses to temperature and hypoxia of the winter frog Rana catesbeiana.

The objective of the present study was to determine the effects of hypoxia and temperature on the cardiovascular and respiratory systems and plasma glucose levels of the winter bullfrog Rana catesbeiana. Body temperature was maintained at 10, 15, 25 and 35 degrees C for measurements of breathing frequency, heart rate, arterial blood pressure, metabolic rate, plasma glucose levels, blood gases and acid-base status. Reducing body temperature from 35 to 10 degrees C decreased (P < 0.001) heart rate (bpm) from 64.0 +/- 3.1 (N = 5) to 12.5 +/- 2.5 (N = 6) and blood pressure (mmHg) (P < 0.05) from 41.9 +/- 2.1 (N = 5) to 33.1 +/- 2.1 (N = 6), whereas no significant changes were observed under hypoxia. Hypoxia-induced changes in breathing frequency and acid-base status were proportional to body temperature, being pronounced at 25 degrees C, less so at 15 degrees C, and absent at 10 degrees C. Hypoxia at 35 degrees C was lethal. Under normoxia, plasma glucose concentration (mg/dl) decreased (P < 0.01) from 53.0 +/- 3.4 (N = 6) to 35.9 +/- 1.7 (N = 6) at body temperatures of 35 and 10 degrees C, respectively. Hypoxia had no significant effect on plasma glucose concentration at 10 and 15 degrees C, but at 25 degrees C there was a significant increase under conditions of 3% inspired O2. The arterial PO2 and pH values were similar to those reported in previous studies on non-estivating Rana catesbeiana, but PaCO2 (37.5 +/- 1.9 mmHg, N = 5) was 3-fold higher, indicating increased plasma bicarbonate levels. The estivating bullfrog may be exposed not only to low temperatures but also to hypoxia. These animals show temperature-dependent responses that may be beneficial since during low body temperatures the sensitivity of most physiological systems to hypoxia is reduced.

Animals↗
PubMed1992

[Idiopathic light eruption].

Idiopathic polymorphous light eruptions (PLE) are photodermatites due to an as yet unidentified photosensitizing agent. Benign estival PLE is the most frequent form: the face is spared, and as soon as the patient has acquired a slight tan the eruption will no longer occur. Juvenile spring eruption affects the free border of the helix and may be regarded as a localized and mild form of estival PLE. Polymorphous light eruptions appear as lesions of the face which may resemble lupus erythematosus; photobiological exploration reproduces the lesions experimentally in 70% of the cases; immunohistochemistry studies are in favour of an immunological mechanism. Solar urticaria is a rare physical urticaria started by UVA, UVB and/or visible light: tolerance to sunlight can be induced by repeated exposures, but it does not last. Hydroa vacciniform is a rare PLE in children with leaves smallpox-like scars; photobiological exploration reproduces the lesions with high doses of UVA applied for 3 consecutive days. The remanent photosensitivity syndrome is characterized by an extreme photosensitivity which may be very disabling, preventing the patient to go outdoors; photo-allergological exploration discloses numerous positive patch-tests or photopatch-tests to various allergens, but the role played by these allergens in the occurrence of photosensitivity remains unclear. The syndrome probably results from an exogenous photosensitivity accident that has not regressed after exclusion of the presumably responsible photoallergens. Many treatments tested for these PLE seem to be effective, but they have not yet been controlled by double-blind trials.

Humans↗
PubMed2005

Greatly elevated urea excretion after air exposure appears to be carrier mediated in the slender lungfish (Protopterus dolloi).

Under aquatic conditions, Protopterus dolloi is ammoniotelic, excreting only small amounts of urea-N. However, upon return to water after 30 d estivation in air, the lungfish excretes only small amounts of ammonia-N but massive amounts of urea-N. A similar pattern is seen after 21-30 d of terrestrialization, a treatment in which the lungfish is air exposed but kept moist throughout. After both treatments, the time course of urea-N excretion is biphasic with an immediate increase, then a fall, and finally a second larger increase that peaks at about 12 h and may be prolonged for several days thereafter. Urea-N excretion rates during the second peak reach 2,000-6,000 micromol N kg(-1) h(-1), two to three orders of magnitude greater than rates in most fish and comparable only to rates in species known to employ UT-A type facilitated diffusion urea transporters. Divided chamber studies and measurements of the clearance rates of [3H]-PEG-4000 (a glomerular filtration and paracellular diffusion marker) and two structural analogs of urea ([14C]-acetamide and [14C]-thiourea) were performed to characterize the two peaks of urea-N excretion. The smaller first peak was almost equally partitioned between the head (including internal and external gills) and the body compartment (including urinary opening), was accompanied by only a modest increase in [14C]-acetamide clearance equal to that in [14C]-thiourea clearance, and could be accounted for by a large but short-lasting increase in [3H]-PEG-4000 clearance (to about fivefold the terrestrial rate). The delayed, much larger second peak in urea-N excretion represented an elevated efflux into both compartments but occurred mainly (72%) via the body rather than the head region. This second peak was accompanied by a substantial increase in [14C]-acetamide clearance but only a modest further rise in [14C]-thiourea clearance. The acetamide to thiourea permeability ratio was typical of UT-A type transporters in other fish. [3H]-PEG-4000 clearance was stable at this time at about double the terrestrial rate, and excretion rates of urea and its analogs were many fold greater than could be accounted for by [3H]-PEG-4000 clearance. We conclude that the first peak may be explained by elevated urinary excretion and paracellular diffusion across the gills upon resubmergence, while the second peak is attributable to a delayed and prolonged activation of a UT-A type facilitated diffusion mechanism, primarily in the skin and perhaps also in branchial epithelia.

Ammonia↗
PubMed2006

The African lungfish (Protopterus dolloi): ionoregulation and osmoregulation in a fish out of water.

Although urea production and metabolism in lungfish have been thoroughly studied, we have little knowledge of how internal osmotic and electrolyte balance are controlled during estivation or in water. We tested the hypothesis that, compared with the body surface of teleosts, the slender African lungfish (Protopterus dolloi) body surface was relatively impermeable to water, Na(+), and Cl(-) due to its greatly reduced gills. Accordingly, we measured the tritiated water ((3)H-H(2)O) flux in P. dolloi in water and during air exposure. In water, (3)H-H(2)O efflux was comparable with the lowest measurements reported in freshwater teleosts, with a rate constant (K) of 17.6% body water h(-1). Unidirectional ion fluxes, measured using (22)Na(+) and (36)Cl(-), indicated that Na(+) and Cl(-) influx was more than 90% lower than values reported in most freshwater teleosts. During air exposure, a cocoon formed within 1 wk that completely covered the dorsolateral body surface. However, there were no disturbances to blood osmotic or ion (Na(+), Cl(-)) balance, despite seven- to eightfold increases in plasma urea after 20 wk. Up to 13-fold increases in muscle urea (on a dry-weight basis) were the likely explanation for the 56% increase in muscle water content observed after 20 wk of air exposure. The possibility that muscle acted as a "water reservoir" during air exposure was supported by the 20% decline in body mass observed during subsequent reimmersion in water. This decline in body mass was equivalent to 28 mL water in a 100-g animal and was very close to the calculated net water gain (approximately 32 mL) observed during the 20-wk period of air exposure. Tritiated water and unidirectional ion fluxes on air-exposed lungfish revealed that the majority of water and ion exchange was via the ventral body surface at rates that were initially similar to aquatic rates. The (3)H-H(2)O flux declined over time but increased upon reimmersion. We conclude that the slender lungfish body surface, including the gills, has relatively low permeability to water and ions but that the ventral surface is an important site of osmoregulation and ionoregulation. We further propose that an amphibian-like combination of ventral skin water and ion permeability, plus internal urea accumulation during air exposure, allows P. dolloi to extract water from its surroundings and to store water in the muscle when the water supply becomes limited.

Air↗
PubMed2005

H2S induces a suspended animation-like state in mice.

Mammals normally maintain their core body temperature (CBT) despite changes in environmental temperature. Exceptions to this norm include suspended animation-like states such as hibernation, torpor, and estivation. These states are all characterized by marked decreases in metabolic rate, followed by a loss of homeothermic control in which the animal's CBT approaches that of the environment. We report that hydrogen sulfide can induce a suspended animation-like state in a nonhibernating species, the house mouse (Mus musculus). This state is readily reversible and does not appear to harm the animal. This suggests the possibility of inducing suspended animation-like states for medical applications.

Animals↗
PubMed1975

Bioenergetic functions of sleep and activity rhythms and their possible relevance to aging.

The hypothesis is proposed that sleep constitutes a period of dormancy in which energy is conserved to partially offset the increased energy demands of homeothermy. Phylogenetic data indicate that the complete psysiological and behavioral manifestations of sleep are unique to homeotherms; furthermore "ontogeny recapitulates phylogeny" in the parallel development of slow wave sleep and thermoregulation as exemplified in the opossum. Thus, sleep constitutes a state of reduced metabolism that may represent a variation on the theme of dormancy, functionally lying on a continuum of energy conservation processes, ranging from inactivity and estivation to torpor and hibernation. The high amounts of sleep in infancy may involve conservation of energy and its consequent availability for growth. Decreased amounts of stage 4 and total sleep with aging in humans may represent reduced energy demands reflected by parallel declines in basal metabolic rate and physical activity. Disruptions of circadian rhythms of sleep and wakefulness in humans produce impairments in mood and performance independent of total amounts of sleep obtained, and reduce the amplitude of physiological rhythms. It is suggested that aging processes might also be affected by such disruptions in activity rhythms.

Aging↗
PubMed1996

Oxidative stress: animal adaptations in nature.

As a consequence of aerobic life, an organism must deal with the continuous generation of reactive oxygen species (O2-, H202, .OH) as byproducts of metabolism and defend itself against the harm that these can do to cellular macromolecules. Organisms protect themselves from such damage with both enzymatic and nonenzymatic antioxidant defenses. However, the reperfusion injuries noted after ischemic insult in mammalian organs and ascribed to a burst of reactive oxygen species produced when oxygenated blood is reintroduced demonstrate that the antioxidant defenses of many organisms can be overwhelmed, Although unusual among most mammals, many organisms routinely experience wide variation in oxygen availability to their tissues due to factors such as environmental oxygen lack, breath-hold diving, extracellular freezing, or apnoeic breathing patterns in arrested metabolic states. In recent studies using various animal models (anoxia-tolerant turtles, freeze-tolerant snakes and frogs, estivating snails) our laboratory has explored the adaptations of antioxidant defenses that allow such organisms to deal with rapid changes in tissue oxygenation with little or no accumulation of damage products. The key to successful transitions in several systems is the induction, during the oxygen-limited state, of elevated activities of antioxidant and associated enzymes, such as catalase, superoxide dismutase, glutathione-S-transferase, and glutathione peroxidase, so that damage during the reintroduction of oxygen (such as lipid peroxidation) is minimized. However, animals that are excellent facultative anaerobes, such as freshwater turtles, appear to deal with potential of oxidative stress during the anoxic-aerobic transition by maintaining constitutively high antioxidant defenses (e.g. enzyme activities similar to those of mammals and much higher than those of anoxia-intolerant lower vertebrates) that can readily accommodate the burst of reactive oxygen species generation when breathing is renewed.

Adaptation, Physiological↗
PubMed2001

Seasonal changes in the preferred body temperature, cardiovascular, and respiratory responses to hypoxia in the toad, Bufo paracnemis.

Estivation is accompanied by a reduction of oxygen consumption in amphibians during drought. We tested the hypothesis that, during the dry season, the toad Bufo paracnemis selects a lower preferred body temperature (T(b)), and would be less sensitive to hypoxia, than during its active period. Therefore, during winter (dry season in São Paulo state, Brazil) and summer, we measured the effects of hypoxia (7% inspired O(2)) on preferred T(b). Additionally, pulmonary ventilation, heart rate, blood pressure, and oxygen consumption were also measured in toads at 15 and 25 degrees C. Blood gases were measured at 25 degrees C. Oxygen consumption was significantly higher during summer in toads at 25 degrees C. Under normoxia, preferred T(b) was higher during summer than during winter, and hypoxia caused a drop in preferred T(b) during both seasons. In both seasons, toads at 15 degrees C showed reduced pulmonary ventilation, heart rate, and blood pressure, and hypoxia had no effect. At 25 degrees C during summer only, hypoxia caused an increase in ventilation. Season had no effect on blood gases. We conclude that B. paracnemis displays an endogenous seasonal pattern of thermoregulation and control of ventilation. The decreased preferred T(b) and the physiological responses to hypoxia may be beneficial to toads encountering drought and when food is not available.

Adaptation, Physiological↗
PubMed1994

Metabolic depression in land snails: in vitro analysis of protein kinase involvement in pyruvate kinase control in isolated Otala lactea tissues.

Isolated tissues from the land snail Otala lactea were used to examine the relationship between protein kinase activity and phosphorylation-induced changes associated with metabolic depression. Hepatopancreas and foot muscle were removed from active and estivating land snails and incubated in vitro under aerobic and anoxic conditions. Pyruvate kinase (PK), cAMP-dependent protein kinase (PKA), and protein kinase second messenger compounds (cyclic AMP and inositol 1,4,5-triphosphate) were measured after incubating the tissues for 4 hours. Pyruvate kinase from the hepatopancreas of active snails was phosphorylated during anoxic incubations as indicated by changes in the I50 value for L-alanine. However, measurements of PKA activity and of cellular cAMP concentrations suggested that PKA activity was lower in these incubated tissues. When foot muscle was used as the tissue source, incubation under anoxic conditions produced no changes in PK activity even though PKA activity was drastically reduced. Analysis of changes in inositol 1,4,5-triphosphate concentrations after tissue incubation showed that they were not consistent with changes in PK activity in either organ. These results suggest that PKA and Ca2+/phospholipid-dependent protein kinase C do not phosphorylate PK during anoxia in land snails. The differences between values measured in incubated tissues and those measured in vivo suggest that isolated O. lactea tissues are not a good in vitro model system for studying metabolic changes associated with depressed metabolism.

Animals↗
PubMed1996

Effect of Zn, Cu, Pb, and Cd on fitness in snails (Helix aspersa).

Juveniles and adults of the Brown garden snail (Helix aspersa Müll.) were fed on an artificial diet contaminated with Zn (ca. 40-12,000 micrograms.g-1 dry wt), Cu (ca. 9-1600 micrograms.g-1 dry wt), pb (ca. 0.4-12,700 micrograms.g-1 dry wt), Cd (ca. 0.16-145 micrograms.g-1 dry wt), and all four metals mixed together for 120 days. Significant negative exponential regressions of food consumption and fecundity on concentrations were found for all treatments. Growth rate was affected significantly only by Zn and mixed treatments. The calculated EC20(consumption) values for juveniles were (in microgram.g1): Zn, 855; Cu, 248; Pb, 5290; Cd, 60; and for adults: Zn, 1240; Cu, 275; Pb, 3120; Cd, 147. In mixed treatment EC20(consumption) values were substantially lower indicating the additive effect of pollution with these four metals. EC20(consumption) for Zn in mixed treatment was 329 micrograms.g-1 for juveniles and 661 micrograms.g-1 for adults. The following EC20 values were estimated for fecundity (in micrograms.g-1): Zn, 1740; Cu, 533; Pb, 6140; Cd, 120; Zn in mixed treatment, 2210. The relative toxicities of the four metals were compared with their ratios in contaminated field sites. Comparing Zn and Cd, for example, even though Zn is ca. 13-24 times less toxic than Cd, it is usually present in plants and forest litter in concentrations ca. 100 times greater than those of Cd. Thus, of these two metals, Zn appeared to be potentially the most important pollutant in ecologically relevant situations. No effect of any treatment on mortality was found during the 4-month experiment. The calculated scenarios of population dynamics under the stress of chronic pollution with mixtures of the four metals revealed that the delayed reproduction due to estivation of snails may be the main cause of population decline at high metal concentrations in food. However, at concentrations at and below ca. 1000 micrograms Zn.g-1 in food, if the reproduction is not delayed the population may persist for a long time (0.25 control number after 50 years).

Aging↗
PubMed1993

Lungfish neurohypophysial hormones: chemical identification of mesotocin in the neurointermediate pituitary of the Australian lungfish Neoceratodus forsteri.

The neurohypophysial hormones contained in the neurointermediate lobe of the pituitary of the Australian lungfish Neoceratodus forsteri have been investigated. Mesotocin was identified by coelution with the synthetic peptide in high-pressure liquid chromatography, by Edman amino acid sequencing, by mass spectrometry, by C-terminal sequencing through carboxypeptidase Y, and cleavage with prolyl endopeptidase. Vasotocin, if present, would be in very small amounts and hydrins were not detected. Oxytocin appears absent. Although Neoceratodus and Protopterus have different habitats, the former being permanently aquatic, the latter burrowing during estivation, the proportions of neurohypophysial hormones stored in neurohypophysis were roughly similar in the two species and not apparently affected by environmental conditions.

Amino Acid Sequence↗
PubMed1989

Vitamin D (soltriol), light, and reproduction.

Evidence from autoradiographic studies with 1,25(OH)2-vitamin D3 (vitamin D, soltriol) labeled with tritium and from the literature indicates that the steroid hormone soltriol regulates and modulates reproductive processes in the female, as it does in the male. Nuclear receptors for soltriol have been discovered in the uterus, oviduct, ovary, mammary gland, placenta, and fetal membranes, as well as in the pituitary and hypothalamus. Soltriol is recognized as a transducer and hormonal messenger of sunlight, acting as a somatotropic activator and modulator of vital processes for the seasonal and estival adaptation of growth, development, and procreation. Its influence on calcium equilibrium is just one of its many functions to serve this goal. This article reviews experimental, clinical, and epidemiologic evidence that suggests the involvement of soltriol in the control of reproductive processes, noting its importance for the onset of puberty, fertility, pregnancy, lactation, and probably sexual behavior. Cooperative actions between soltriol and other steroid hormones, especially estradiol, are pointed out.

Animals↗
PubMed1992

Seasonal fluctuations in hormones and behavior of free-living male California ground squirrels (Spermophilus beecheyi).

Plasma testosterone (T), prolactin (PRL), and behavior were monitored concurrently in free-living male California ground squirrels (Spermophilus beecheyi). Male plasma T peaked in January, 2-3 months after males emerged from their annual period of estivation. PRL peaked 6 to 10 weeks after T. Temporal patterns of space use by males were directly correlated with plasma T levels, but seasonal maxima in rates of most monitored male behaviors occurred 4 weeks after the T peak. No monitored behavior rates were correlated with plasma PRL values. Yearling and adult males did not differ with respect to circulating levels of either T or PRL. Both groups of males mated in our study population, and did not differ significantly with respect to rates of most monitored behaviors. However, yearlings pursued fewer females, mated less frequently, and required more mounts to complete each copulation than did adults. We suggest that T serves an important priming function for various seasonally fluctuating behaviors, but also that mating experience might influence the efficiency of copulatory behavior in this species.

Animals↗
PubMed1981

Functional morphology of the gills of the bowfin, Amia calva L., with special reference to their significance during air exposure.

The bowfin, Amia calva is a facultative air breathing fish restricted to North America and is reported to estivate. The relative and functional gill surface areas of A. calva are not reduced, as in many amphibious fish, but have areas comparable to many completely aquatic species. The secondary lamellae are fused to form a lattice-work of rectangular pores, a gill arrangement unique among fresh-water fishes. This highly modified gill structure imparts considerable rigidity such that these do not collapse upon air exposure. In vivo blood gas measurements from air exposed Amia reveal that these gills must be free of water, since there is both O2 uptake and CO2 excretion across them. The observed ventilatory motions therefore pass air over the secondary lamellae for diffusive gas exchange during air exposure. In the artificial conditions of our experiments, however, air exposure was associated with a marked acidosis and the fish died within 2 hours of being returned to normoxic water.

Acidosis↗
PubMed1990

Systemic administration of kainic acid produces elevations in TRH in rat central nervous system.

Several studies have suggested that the concentration of thyrotropin releasing hormone (TRH) in the central nervous system (CNS) is influenced by the level of CNS activation. Hibernation in the ground squirrel and estivation in the lungfish result in region-specific decreases in TRH concentrations. Repeated electroconvulsive shock (ECS) and amygdaloid kindling have been shown to result in elevations of TRH in limbic brain regions. In the present study, limbic seizures induced by systemic administration of kainic acid resulted in substantial increases in the TRH content of posterior cortex and of dorsal and ventral hippocampus, and in moderate elevations in anterior cortex, amygdala/piriform cortex and corpus striatum. Maximal elevations in TRH were observed 2-4 days after kainic acid administration, and by 14 days TRH levels were similar to control values, with the exception of the dorsal hippocampus, which exhibited more prolonged elevations in TRH levels. Prior exposure to limbic seizure activity attenuated the magnitude of TRH elevation in response to a second administration of kainic acid in the posterior cortex but in no other region. These results indicate that seizure-related processes or events influence TRH systems in the CNS. Neuronal populations involved in limbic seizure induced damage may be involved in the modulation of posterior cortical TRH levels.

Animals↗