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Deborah M Buehler - One of the best experts on this subject based on the ideXlab platform.
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constitutive Immune Function in european starlings sturnus vulgaris is decreased immediately after an endurance flight in a wind tunnel
The Journal of Experimental Biology, 2012Co-Authors: Silke Nebel, Deborah M Buehler, Ulf Bauchinger, Lillie A Langlois, Michelle Boyles, Alexander R Gerson, Edwin R Price, Scott R Mcwilliams, Christopher G GuglielmoAbstract:Life-history theory predicts that animals face a trade-off in energy allocation between performing strenuous exercise, such as migratory flight, and mounting an Immune response. We experimentally tested this prediction by studying Immune Function in European starlings, Sturnus vulgaris , flown in a wind tunnel. Specifically, we predicted that constitutive Immune Function decreases in response to training and, additionally, in response to immediate exercise. We compared constitutive Immune Function among three groups: (1) ‘untrained’ birds that were kept in cages and were not flown; (2) ‘trained’ birds that received flight training over a 15 day period and performed a 1-4 h continuous flight, after which they rested for 48 h before being sampled; and (3) ‘post-flight’ birds that differed from the ‘trained’ group only in being sampled immediately after the final flight. A bird in our trained group represents an individual during migration that has been resting between migratory flights for at least 2 days. A bird in our post-flight group represents an individual that has just completed a migratory flight and has not yet had time to recover. Three of our four indicators (haptoglobin, agglutination and lysis) showed the predicted decrease in Immune Function in the post-flight group, and two indicators (haptoglobin, agglutination) showed the predicted decreasing trend from the untrained to trained to post-flight group. Haptoglobin levels were negatively correlated with flight duration. No effect of training or flight was detected on leukocyte profiles. Our results suggest that in European starlings, constitutive Immune Function is decreased more as a result of immediate exercise than of exercise training. Because of the recent emergence of avian-borne diseases, understanding the trade-offs and challenges faced by long-distance migrants has gained a new level of relevance and urgency.
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constitutive Immune Function in european starlings sturnus vulgaris is decreased immediately after an endurance flight in a wind tunnel
The Journal of Experimental Biology, 2012Co-Authors: Silke Nebel, Deborah M Buehler, Ulf Bauchinger, Lillie A Langlois, Michelle Boyles, Alexander R Gerson, Edwin R Price, Scott R Mcwilliams, Christopher G GuglielmoAbstract:Life-history theory predicts that animals face a trade-off in energy allocation between performing strenuous exercise, such as migratory flight, and mounting an Immune response. We experimentally tested this prediction by studying Immune Function in European starlings, Sturnus vulgaris , flown in a wind tunnel. Specifically, we predicted that constitutive Immune Function decreases in response to training and, additionally, in response to immediate exercise. We compared constitutive Immune Function among three groups: (1) ‘untrained’ birds that were kept in cages and were not flown; (2) ‘trained’ birds that received flight training over a 15 day period and performed a 1-4 h continuous flight, after which they rested for 48 h before being sampled; and (3) ‘post-flight’ birds that differed from the ‘trained’ group only in being sampled immediately after the final flight. A bird in our trained group represents an individual during migration that has been resting between migratory flights for at least 2 days. A bird in our post-flight group represents an individual that has just completed a migratory flight and has not yet had time to recover. Three of our four indicators (haptoglobin, agglutination and lysis) showed the predicted decrease in Immune Function in the post-flight group, and two indicators (haptoglobin, agglutination) showed the predicted decreasing trend from the untrained to trained to post-flight group. Haptoglobin levels were negatively correlated with flight duration. No effect of training or flight was detected on leukocyte profiles. Our results suggest that in European starlings, constitutive Immune Function is decreased more as a result of immediate exercise than of exercise training. Because of the recent emergence of avian-borne diseases, understanding the trade-offs and challenges faced by long-distance migrants has gained a new level of relevance and urgency.
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limited access to food and physiological trade offs in a long distance migrant shorebird ii constitutive Immune Function and the acute phase response
Physiological and Biochemical Zoology, 2009Co-Authors: Deborah M Buehler, Francisco Encinasviso, Magali Petit, Francois Vezina, Irene B Tieleman, Theunis PiersmaAbstract:In response to unbalanced energy budgets, animals must allocate resources among competing physiological systems to maximize fitness. Constraints can be imposed on energy availability or energy expenditure, and adjustments can be made via changes in metabolism or trade-offs with competing demands such as body-mass maintenance and Immune Function. This study investigates changes in constitutive Immune Function and the acute-phase response in shorebirds (red knots) faced with limited access time to food. We separated birds into two experimental groups receiving either 6 h or 22 h of food access and measured constitutive Immune Function. After 3 wk, we induced an acute-phase response, and after 1 wk of recovery, we switched the groups to the opposite food treatment and measured constitutive Immune Function again. We found little effect of food treatment on constitutive Immune Function, which suggests that even under resource limitation, a baseline level of Immune Function is maintained. However, birds enduring limited access to food suppressed aspects of the acute-phase response (decreased feeding and mass loss) to maintain energy intake, and they downregulated thermoregulatory adjustments to food treatment to maintain body temperature during simulated infection. Thus, under resource-limited conditions, birds save energy on the most costly aspects of Immune defense.
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limited access to food and physiological trade offs in a long distance migrant shorebird ii constitutive Immune Function and the acute phase response
Physiological and Biochemical Zoology, 2009Co-Authors: Deborah M Buehler, Francisco Encinasviso, Magali Petit, Francois Vezina, Irene B Tieleman, Theunis PiersmaAbstract:Abstract In response to unbalanced energy budgets, animals must allocate resources among competing physiological systems to maximize fitness. Constraints can be imposed on energy availability or energy expenditure, and adjustments can be made via changes in metabolism or trade‐offs with competing demands such as body‐mass maintenance and Immune Function. This study investigates changes in constitutive Immune Function and the acute‐phase response in shorebirds (red knots) faced with limited access time to food. We separated birds into two experimental groups receiving either 6 h or 22 h of food access and measured constitutive Immune Function. After 3 wk, we induced an acute‐phase response, and after 1 wk of recovery, we switched the groups to the opposite food treatment and measured constitutive Immune Function again. We found little effect of food treatment on constitutive Immune Function, which suggests that even under resource limitation, a baseline level of Immune Function is maintained. However, bird...
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age and environment affect constitutive Immune Function in red knots calidris canutus
Journal of Ornithology, 2009Co-Authors: Deborah M Buehler, Irene B Tieleman, Theunis PiersmaAbstract:We studied subspecies, age and environmental effects on constitutive Immune Function (natural antibody and complement titres, haptoglobin activity and leukocyte concentrations) in Red Knots (Calidris canutus). We compared C. c. islandica and C. c. canutus in the Wadden Sea and found no difference in Immune Function between subspecies. However, C. c. canutus on their wintering grounds in Banc d’Arguin had higher natural antibody and lower complement levels than C. c. canutus or C. c. islandica in the Wadden Sea. This suggests that Immune Function is determined more by the surrounding environment than by subspecies. We also compared age classes in the Wadden Sea and found that first year birds had significantly lower natural antibody levels than adults, but that second year birds no longer differed from adults. Finally, we examined the interaction of age and environment in Banc d’Arguin. We found that first year birds (but not adults) in a low quality habitat had higher leukocyte concentrations than first year birds or adults in a high quality habitat. Differences in available resources and defence needs between environments, and differences among individuals differentially distributed between sites, are likely important contributors to the variation in Immune Function we report. Future studies, which examine these factors on wild birds, will be important for our understanding of how animals Function in their natural environment. (220).
Theunis Piersma - One of the best experts on this subject based on the ideXlab platform.
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limited access to food and physiological trade offs in a long distance migrant shorebird ii constitutive Immune Function and the acute phase response
Physiological and Biochemical Zoology, 2009Co-Authors: Deborah M Buehler, Francisco Encinasviso, Magali Petit, Francois Vezina, Irene B Tieleman, Theunis PiersmaAbstract:In response to unbalanced energy budgets, animals must allocate resources among competing physiological systems to maximize fitness. Constraints can be imposed on energy availability or energy expenditure, and adjustments can be made via changes in metabolism or trade-offs with competing demands such as body-mass maintenance and Immune Function. This study investigates changes in constitutive Immune Function and the acute-phase response in shorebirds (red knots) faced with limited access time to food. We separated birds into two experimental groups receiving either 6 h or 22 h of food access and measured constitutive Immune Function. After 3 wk, we induced an acute-phase response, and after 1 wk of recovery, we switched the groups to the opposite food treatment and measured constitutive Immune Function again. We found little effect of food treatment on constitutive Immune Function, which suggests that even under resource limitation, a baseline level of Immune Function is maintained. However, birds enduring limited access to food suppressed aspects of the acute-phase response (decreased feeding and mass loss) to maintain energy intake, and they downregulated thermoregulatory adjustments to food treatment to maintain body temperature during simulated infection. Thus, under resource-limited conditions, birds save energy on the most costly aspects of Immune defense.
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limited access to food and physiological trade offs in a long distance migrant shorebird ii constitutive Immune Function and the acute phase response
Physiological and Biochemical Zoology, 2009Co-Authors: Deborah M Buehler, Francisco Encinasviso, Magali Petit, Francois Vezina, Irene B Tieleman, Theunis PiersmaAbstract:Abstract In response to unbalanced energy budgets, animals must allocate resources among competing physiological systems to maximize fitness. Constraints can be imposed on energy availability or energy expenditure, and adjustments can be made via changes in metabolism or trade‐offs with competing demands such as body‐mass maintenance and Immune Function. This study investigates changes in constitutive Immune Function and the acute‐phase response in shorebirds (red knots) faced with limited access time to food. We separated birds into two experimental groups receiving either 6 h or 22 h of food access and measured constitutive Immune Function. After 3 wk, we induced an acute‐phase response, and after 1 wk of recovery, we switched the groups to the opposite food treatment and measured constitutive Immune Function again. We found little effect of food treatment on constitutive Immune Function, which suggests that even under resource limitation, a baseline level of Immune Function is maintained. However, bird...
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age and environment affect constitutive Immune Function in red knots calidris canutus
Journal of Ornithology, 2009Co-Authors: Deborah M Buehler, Irene B Tieleman, Theunis PiersmaAbstract:We studied subspecies, age and environmental effects on constitutive Immune Function (natural antibody and complement titres, haptoglobin activity and leukocyte concentrations) in Red Knots (Calidris canutus). We compared C. c. islandica and C. c. canutus in the Wadden Sea and found no difference in Immune Function between subspecies. However, C. c. canutus on their wintering grounds in Banc d’Arguin had higher natural antibody and lower complement levels than C. c. canutus or C. c. islandica in the Wadden Sea. This suggests that Immune Function is determined more by the surrounding environment than by subspecies. We also compared age classes in the Wadden Sea and found that first year birds had significantly lower natural antibody levels than adults, but that second year birds no longer differed from adults. Finally, we examined the interaction of age and environment in Banc d’Arguin. We found that first year birds (but not adults) in a low quality habitat had higher leukocyte concentrations than first year birds or adults in a high quality habitat. Differences in available resources and defence needs between environments, and differences among individuals differentially distributed between sites, are likely important contributors to the variation in Immune Function we report. Future studies, which examine these factors on wild birds, will be important for our understanding of how animals Function in their natural environment. (220).
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seasonal redistribution of Immune Function in a migrant shorebird annual cycle effects override adjustments to thermal regime
The American Naturalist, 2008Co-Authors: Deborah M Buehler, Theunis Piersma, Kevin D Matson, Irene B TielemanAbstract:Throughout the annual cycle, demands on competing physiological systems change, and animals must allocate resources to maximize fitness. Immune Function is one such system and is important for survival. Yet detailed empirical data tracking Immune Function over the entire annual cycle are lacking for most wild animals. We measured constitutive Immune indices once a month for a year on captive red knots (Calidris canutus). We also examined temperature as an environmental contributor to Immune variation by manipulating ambient temperature to vary energy expenditure. To identify relationships among Immune indices, we performed principal-component analysis. We found significant repeatability in Immune indices over the annual cycle and covariation of Immune indices within and among individuals. This covariation suggests Immune strategies as individual traits among individuals and the use of different Immune strategies during different annual-cycle stages within individuals. Over the annual cycle, both higher-cost phagocyte-based immunity and lower-cost lymphocyte-based immunity were high during mass change, but there was a clear shift toward lower-cost lymphocyte-based immunity during peak molt. Experimental manipulation of temperature had little effect on annual variation in Immune Function. This suggests that other environmental factors, such as food availability and disease, should also be examined in the future.
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constitutive Immune Function responds more slowly to handling stress than corticosterone in a shorebird
Physiological and Biochemical Zoology, 2008Co-Authors: Deborah M Buehler, Irene B Tieleman, Nina Bhola, Daliborka Barjaktarov, Wolfgang Goymann, Ingrid Schwabl, Theunis PiersmaAbstract:Abstract Ecological immunologists are interested in how Immune Function changes during different seasons and under different environmental conditions. However, an obstacle to answering such questions is discerning the effects of biological factors of interest and investigation artifacts such as handling stress. Here we examined handling stress and its effects on constitutive (noninduced) Immune Function via two protocols on captive red knots (Calidris canutus). We investigated how constitutive immunity responds to handling stress, how quickly these changes take place, and the practical implications for researchers interested in sampling baseline Immune levels. We found that Staphylococcus aureus and Candida albicans killing increased with handling stress while total leukocyte and lymphocyte concentrations decreased. However, although corticosterone increased significantly and rapidly in response to handling stress, none of the 10 measures of constitutive immunity that we tested differed significantly from...
Irene B Tieleman - One of the best experts on this subject based on the ideXlab platform.
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limited access to food and physiological trade offs in a long distance migrant shorebird ii constitutive Immune Function and the acute phase response
Physiological and Biochemical Zoology, 2009Co-Authors: Deborah M Buehler, Francisco Encinasviso, Magali Petit, Francois Vezina, Irene B Tieleman, Theunis PiersmaAbstract:In response to unbalanced energy budgets, animals must allocate resources among competing physiological systems to maximize fitness. Constraints can be imposed on energy availability or energy expenditure, and adjustments can be made via changes in metabolism or trade-offs with competing demands such as body-mass maintenance and Immune Function. This study investigates changes in constitutive Immune Function and the acute-phase response in shorebirds (red knots) faced with limited access time to food. We separated birds into two experimental groups receiving either 6 h or 22 h of food access and measured constitutive Immune Function. After 3 wk, we induced an acute-phase response, and after 1 wk of recovery, we switched the groups to the opposite food treatment and measured constitutive Immune Function again. We found little effect of food treatment on constitutive Immune Function, which suggests that even under resource limitation, a baseline level of Immune Function is maintained. However, birds enduring limited access to food suppressed aspects of the acute-phase response (decreased feeding and mass loss) to maintain energy intake, and they downregulated thermoregulatory adjustments to food treatment to maintain body temperature during simulated infection. Thus, under resource-limited conditions, birds save energy on the most costly aspects of Immune defense.
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limited access to food and physiological trade offs in a long distance migrant shorebird ii constitutive Immune Function and the acute phase response
Physiological and Biochemical Zoology, 2009Co-Authors: Deborah M Buehler, Francisco Encinasviso, Magali Petit, Francois Vezina, Irene B Tieleman, Theunis PiersmaAbstract:Abstract In response to unbalanced energy budgets, animals must allocate resources among competing physiological systems to maximize fitness. Constraints can be imposed on energy availability or energy expenditure, and adjustments can be made via changes in metabolism or trade‐offs with competing demands such as body‐mass maintenance and Immune Function. This study investigates changes in constitutive Immune Function and the acute‐phase response in shorebirds (red knots) faced with limited access time to food. We separated birds into two experimental groups receiving either 6 h or 22 h of food access and measured constitutive Immune Function. After 3 wk, we induced an acute‐phase response, and after 1 wk of recovery, we switched the groups to the opposite food treatment and measured constitutive Immune Function again. We found little effect of food treatment on constitutive Immune Function, which suggests that even under resource limitation, a baseline level of Immune Function is maintained. However, bird...
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age and environment affect constitutive Immune Function in red knots calidris canutus
Journal of Ornithology, 2009Co-Authors: Deborah M Buehler, Irene B Tieleman, Theunis PiersmaAbstract:We studied subspecies, age and environmental effects on constitutive Immune Function (natural antibody and complement titres, haptoglobin activity and leukocyte concentrations) in Red Knots (Calidris canutus). We compared C. c. islandica and C. c. canutus in the Wadden Sea and found no difference in Immune Function between subspecies. However, C. c. canutus on their wintering grounds in Banc d’Arguin had higher natural antibody and lower complement levels than C. c. canutus or C. c. islandica in the Wadden Sea. This suggests that Immune Function is determined more by the surrounding environment than by subspecies. We also compared age classes in the Wadden Sea and found that first year birds had significantly lower natural antibody levels than adults, but that second year birds no longer differed from adults. Finally, we examined the interaction of age and environment in Banc d’Arguin. We found that first year birds (but not adults) in a low quality habitat had higher leukocyte concentrations than first year birds or adults in a high quality habitat. Differences in available resources and defence needs between environments, and differences among individuals differentially distributed between sites, are likely important contributors to the variation in Immune Function we report. Future studies, which examine these factors on wild birds, will be important for our understanding of how animals Function in their natural environment. (220).
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seasonal redistribution of Immune Function in a migrant shorebird annual cycle effects override adjustments to thermal regime
The American Naturalist, 2008Co-Authors: Deborah M Buehler, Theunis Piersma, Kevin D Matson, Irene B TielemanAbstract:Throughout the annual cycle, demands on competing physiological systems change, and animals must allocate resources to maximize fitness. Immune Function is one such system and is important for survival. Yet detailed empirical data tracking Immune Function over the entire annual cycle are lacking for most wild animals. We measured constitutive Immune indices once a month for a year on captive red knots (Calidris canutus). We also examined temperature as an environmental contributor to Immune variation by manipulating ambient temperature to vary energy expenditure. To identify relationships among Immune indices, we performed principal-component analysis. We found significant repeatability in Immune indices over the annual cycle and covariation of Immune indices within and among individuals. This covariation suggests Immune strategies as individual traits among individuals and the use of different Immune strategies during different annual-cycle stages within individuals. Over the annual cycle, both higher-cost phagocyte-based immunity and lower-cost lymphocyte-based immunity were high during mass change, but there was a clear shift toward lower-cost lymphocyte-based immunity during peak molt. Experimental manipulation of temperature had little effect on annual variation in Immune Function. This suggests that other environmental factors, such as food availability and disease, should also be examined in the future.
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constitutive Immune Function responds more slowly to handling stress than corticosterone in a shorebird
Physiological and Biochemical Zoology, 2008Co-Authors: Deborah M Buehler, Irene B Tieleman, Nina Bhola, Daliborka Barjaktarov, Wolfgang Goymann, Ingrid Schwabl, Theunis PiersmaAbstract:Abstract Ecological immunologists are interested in how Immune Function changes during different seasons and under different environmental conditions. However, an obstacle to answering such questions is discerning the effects of biological factors of interest and investigation artifacts such as handling stress. Here we examined handling stress and its effects on constitutive (noninduced) Immune Function via two protocols on captive red knots (Calidris canutus). We investigated how constitutive immunity responds to handling stress, how quickly these changes take place, and the practical implications for researchers interested in sampling baseline Immune levels. We found that Staphylococcus aureus and Candida albicans killing increased with handling stress while total leukocyte and lymphocyte concentrations decreased. However, although corticosterone increased significantly and rapidly in response to handling stress, none of the 10 measures of constitutive immunity that we tested differed significantly from...
Randy J Nelson - One of the best experts on this subject based on the ideXlab platform.
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photorefractoriness of Immune Function in male siberian hamsters phodopus sungorus
Journal of Neuroendocrinology, 2002Co-Authors: Brian J. Prendergast, Katherine E Wynneedwards, Steven M Yellon, Randy J NelsonAbstract:Short days induce multiple changes in reproductive and Immune Function in Siberian hamsters. Short-day reproductive inhibition in this species is regulated by an endogenous timing mechanism; after approximately 20 weeks in short days, neuroendocrine refractoriness to short-day patterns of melatonin develops, triggering spontaneous recrudescence of the reproductive system. It is unknown whether analogous mechanisms control Immune Function, or if photoperiodic changes in Immune Function are masked by prevailing photoperiod. In Experiment 1, 3 weeks of exposure to long days was not sufficient to induce long-day-like enhancement of in vitro lymphocyte proliferation in short-day adapted male Siberian hamsters. Experiment 2 tested the hypothesis that immunological photorefractoriness is induced by prolonged exposure to short days. Adult male hamsters were gonadectomized or sham-gonadectomized and housed in long (14 h light/day) or short (10 h light/day) photoperiods for 12, 32 or 40 weeks. Somatic and reproductive regression occurred after 12 weeks in short days, and spontaneous recrudescence was complete after 32-40 weeks in short days, indicative of somatic and reproductive photorefractoriness. In gonad-intact hamsters, 12 weeks of exposure to short days decreased the number of circulating granulocytes and increased the number of B-like lymphocytes. After 32 weeks in short days, these measures were restored to long-day values, indicative of photorefractoriness; castration eliminated these effects of photoperiod. In both intact and castrated hamsters, in vitro proliferation of splenic lymphocytes was inhibited by 12 weeks of exposure to short days. After 40 weeks in short days lymphocyte proliferation was restored to long-day values in intact hamsters, but remained suppressed in castrated hamsters. These results suggest that short-day-induced inhibition of lymphocyte Function does not depend on gonadal regression, but that spontaneous recrudescence of this measure is dependent on gonadal recrudescence. In Experiment 3, in vitro treatment with melatonin enhanced basal proliferation of lymphocytes from male hamsters exposed to short days for 12 weeks, but had no effect on lymphocytes of photorefractory hamsters or long-day control hamsters. Lymphocytes of castrated hamsters were unresponsive to in vitro melatonin, suggesting that photoperiodic changes in gonadal hormone secretion may be required to activate mechanisms which permit differential responsiveness to melatonin depending on phase in the annual reproductive cycle. Together, these data indicate that, similar to the reproductive system, the Immune system of male Siberian hamsters exhibits refractoriness to short days.
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leptin effects on Immune Function and energy balance are photoperiod dependent in siberian hamsters phodopus sungorus
Endocrinology, 2001Co-Authors: Deborah L Drazen, Gregory E Demas, Randy J NelsonAbstract:Many adaptations have evolved in small mammals to maximize survival during winter. One such coping tactic in many species is an alteration of Immune Function in advance of the stressful conditions of winter. Leptin is a hormone produced by adipose tissue, and in addition to its central role in energy metabolism, leptin mediates the interactions among energy allocation, Immune Function, and reproduction. To examine this interaction further, exogenous leptin was administered for 2 weeks via osmotic minipumps to Siberian hamsters (Phodopus sungorus) housed in long or short days for a total of 12 weeks. Short-day hamsters displayed the expected reductions in humoral Immune Function, body mass, fat mass, and food intake. In Exp 1, exogenous leptin counteracted the reduction in food intake and the suppression of Immune Function in short days. In Exp 2, when the leptin-induced increase in food intake in short-day hamsters was prevented, leptin did not enhance Immune Function. In most of the measured fat pads and...
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in vitro melatonin treatment enhances cell mediated Immune Function in male prairie voles microtus ochrogaster
Journal of Pineal Research, 2001Co-Authors: Lance J Kriegsfeld, Deborah L Drazen, Randy J NelsonAbstract:The present study was designed (1) to determine the extent to which male prairie voles (Microtus ochrogaster) alter Immune status in response to short-day lengths, (2) to evaluate the role of melatonin in coordinating these alterations in Immune Function, and (3) to assess the association between alterations in Immune Function and reproductive responsiveness to photoperiod. Male voles were housed in either long- or short-day lengths for 10 wk; voles in short days were subdivided into reproductive ''responders'' (R) or ''non-responders'' (NR) based on testicular mass at autopsy. After 10 wk of exposure to photoperiodic conditions, cell-mediated Immune Function was evaluated using an in vitro splenocyte proliferation assay. The direct effects of melatonin on Immune cells were evaluated by adding melatonin to one-half of the cultures in each experimental condition. Melatonin treatment led to enhanced splenocyte proliferation for all experimental groups. Neither photoperiodic condition nor reproductive status was associated with alterations in Immune Function or the degree of immuno-enhancing effects of melatonin. Taken together, the results of the present study suggest that melatonin is capable of enhancing Immune Function in male voles potentially by acting directly on Immune cells.
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photoperiod ambient temperature and food availability interact to affect reproductive and Immune Function in adult male deer mice peromyscus maniculatus
Journal of Biological Rhythms, 1998Co-Authors: Gregory E Demas, Randy J NelsonAbstract:Winter is often stressful. Increased energetic demands in winter and concurrent reductions in energy availability can lead to an energetic imbalance and compromise survival. To increase the odds of surviving winter, individuals of some nontropical rodent species have evolved mechanisms to enhance Immune Function in advance of harsh winter conditions. Short day lengths provide a proximate cue for enhancement of Immune Function, an adaptive Functional response to counter environmental stress-induced reduction in Immune Function. In the present study, photoperiod, ambient temperature, and food availability were manipulated and reproductive Function and cell-mediated immunity were assessed in adult male deer mice (Peromyscus maniculatus). Mice maintained in short days regressed their reproductive systems and displayed enhanced Immune Function compared to long-day animals. Reduced food availability elevated corticosterone concentrations and suppressed reproductive and Immune Function, whereas ambient temperatu...
Francois Vezina - One of the best experts on this subject based on the ideXlab platform.
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limited access to food and physiological trade offs in a long distance migrant shorebird ii constitutive Immune Function and the acute phase response
Physiological and Biochemical Zoology, 2009Co-Authors: Deborah M Buehler, Francisco Encinasviso, Magali Petit, Francois Vezina, Irene B Tieleman, Theunis PiersmaAbstract:In response to unbalanced energy budgets, animals must allocate resources among competing physiological systems to maximize fitness. Constraints can be imposed on energy availability or energy expenditure, and adjustments can be made via changes in metabolism or trade-offs with competing demands such as body-mass maintenance and Immune Function. This study investigates changes in constitutive Immune Function and the acute-phase response in shorebirds (red knots) faced with limited access time to food. We separated birds into two experimental groups receiving either 6 h or 22 h of food access and measured constitutive Immune Function. After 3 wk, we induced an acute-phase response, and after 1 wk of recovery, we switched the groups to the opposite food treatment and measured constitutive Immune Function again. We found little effect of food treatment on constitutive Immune Function, which suggests that even under resource limitation, a baseline level of Immune Function is maintained. However, birds enduring limited access to food suppressed aspects of the acute-phase response (decreased feeding and mass loss) to maintain energy intake, and they downregulated thermoregulatory adjustments to food treatment to maintain body temperature during simulated infection. Thus, under resource-limited conditions, birds save energy on the most costly aspects of Immune defense.
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limited access to food and physiological trade offs in a long distance migrant shorebird ii constitutive Immune Function and the acute phase response
Physiological and Biochemical Zoology, 2009Co-Authors: Deborah M Buehler, Francisco Encinasviso, Magali Petit, Francois Vezina, Irene B Tieleman, Theunis PiersmaAbstract:Abstract In response to unbalanced energy budgets, animals must allocate resources among competing physiological systems to maximize fitness. Constraints can be imposed on energy availability or energy expenditure, and adjustments can be made via changes in metabolism or trade‐offs with competing demands such as body‐mass maintenance and Immune Function. This study investigates changes in constitutive Immune Function and the acute‐phase response in shorebirds (red knots) faced with limited access time to food. We separated birds into two experimental groups receiving either 6 h or 22 h of food access and measured constitutive Immune Function. After 3 wk, we induced an acute‐phase response, and after 1 wk of recovery, we switched the groups to the opposite food treatment and measured constitutive Immune Function again. We found little effect of food treatment on constitutive Immune Function, which suggests that even under resource limitation, a baseline level of Immune Function is maintained. However, bird...
