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Thermoregulation
Kinds of Thermoregulation Selected AbstractsThresholds of Response in Nest Thermoregulation by Worker Bumble Bees, Bombus bifarius nearcticus (Hymenoptera: Apidae)ETHOLOGY, Issue 5 2001Sean O'Donnell Regulation of nest temperature is important to the fitness of eusocial insect colonies. To maintain appropriate conditions for the developing brood, workers must exhibit thermoregulatory responses to ambient temperature. Because nest-mate workers differ in task performance, thermoregulatory behavior provides an opportunity to test threshold of response models for the regulation of division of labor. We found that worker bumble bees (Bombus bifarius nearcticus) responded to changes in ambient temperature by altering their rates of performing two tasks , wing fanning and brood cell incubation. At the colony level, the rate of incubating decreased, and the rate of fanning increased, with increasing temperature. Changes in the number of workers performing these tasks were more important to the colony response than changes in workers' task performance rates. At the individual level, workers' lifetime rates of incubation and fanning were positively correlated, and most individuals did not specialize exclusively on either of these temperature-sensitive tasks. However, workers differed in the maximum temperature at which they incubated and in the minimum temperature at which they fanned. More individuals fanned at high and incubated at low temperatures. Most of the workers that began incubating at higher temperatures continued performing this task at lower temperatures, when additional nest-mates became active. The converse was true for fanning behavior. These data are consistent with a threshold of response model for thermoregulatory behavior of B. bifarius workers. [source] Cortical control of thermoregulatory sympathetic activationEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2010M. Fechir Abstract Thermoregulation enables adaptation to different ambient temperatures. A complex network of central autonomic centres may be involved. In contrast to the brainstem, the role of the cortex has not been clearly evaluated. This study was therefore designed to address cerebral function during a whole thermoregulatory cycle (cold, neutral and warm stimulation) using 18-fluordeoxyglucose-PET (FDG-PET). Sympathetic activation parameters were co-registered. Ten healthy male volunteers were examined three times on three different days in a water-perfused whole-body suit. After a baseline period (32°C), temperature was either decreased to 7°C (cold), increased to 50°C (warm) or kept constant (32°C, neutral), thereafter the PET examination was performed. Cerebral glucose metabolism was increased in infrapontine brainstem and cerebellar hemispheres during cooling and warming, each compared with neutral temperature. Simultaneously, FDG uptake decreased in the bilateral anterior/mid-cingulate cortex during warming, and in the right insula during cooling and warming. Conjunction analyses revealed that right insular deactivation and brainstem activation appeared both during cold and warm stimulation. Metabolic connectivity analyses revealed positive correlations between the cortical activations, and negative correlations between these cortical areas and brainstem/cerebellar regions. Heart rate changes negatively correlated with glucose metabolism in the anterior cingulate cortex and in the middle frontal gyrus/dorsolateral prefrontal cortex, and changes of sweating with glucose metabolism in the posterior cingulate cortex. In summary, these results suggest that the cerebral cortex exerts an inhibitory control on autonomic centres located in the brainstem or cerebellum. These findings may represent reasonable explanations for sympathetic hyperactivity, which occurs, for example, after hemispheric stroke. [source] The role of water abundance, thermoregulation, perceived predation risk and interference competition in water access by African herbivoresAFRICAN JOURNAL OF ECOLOGY, Issue 3 2008Marion Valeix Abstract In African savannas, surface water can become limiting and an understanding of how animals address the trade-offs between different constraints to access this resource is needed. Here, we describe water access by ten African herbivore species in Hwange National Park, Zimbabwe, and we explore four possible determinants of the observed behaviours: water abundance, thermoregulation, perceived predation risk and interference competition. On average, herbivores were observed to drink in 80% of visits to a waterhole. The probability of drinking was higher in 2003 (474 mm) than in 2004 (770 mm), and at the end of the dry season than at its beginning. For larger species, this probability may also be related to risks of interference competition with elephants or other herbivores. For smaller species, this probability may also be related to the perceived risk of predation. We also investigate the time spent accessing water to drink. The influence of herd size and the presence of young on the time spent accessing water for most species suggests that perceived predation risk plays a role. Thermoregulation also affects this time: during the hottest periods, herbivores spend less time in open areas, unless when wind is strong, probably owing to evapotranspired heat loss. Résumé Dans les savanes africaines, l'eau de surface disponible peut devenir un facteur limitant et il est nécessaire de comprendre comment les animaux agissent face aux différentes contraintes que pose l'accès à cette ressource. Nous décrivons ici l'accès à l'eau de dix herbivores africains du Parc National de Hwange, au Zimbabwe, et nous explorons quatre facteurs qui sont peut-être déterminants dans les comportements observés: l'abondance de l'eau, la thermorégulation, le risque de prédation ressenti et la compétition/ interférence. En moyenne, on a observé que les herbivores buvaient lors de 80% de leurs visites au point d'eau. La probabilité qu'ils boivent étai plus forte en 2003 (474 mm) qu'en 2004 (770 mm), et à la fin de la saison sèche qu'au début. Pour les plus grandes espèces, cette probabilité pourrait aussi être liée aux risques de compétition par interférence avec les éléphants ou d'autres herbivores. Pour les plus petites espèces, cette probabilité pourrait aussi être liée au risque de prédation ressenti. Nous avons aussi étudié le temps passéà se rendre au point d'eau pour y boire. L'influence de la taille du groupe et de la présence de jeunes sur le temps pris par la plupart des espèces pour se rendre au point d'eau laisse penser que la perception du risque de prédation joue un rôle. La thermorégulation affecte aussi cette durée: pendant les périodes les plus chaudes, les herbivores passent moins de temps dans les espaces ouverts, sauf si le vent est fort, probablement à cause de la perte de chaleur par évapotranspiration. [source] Thermoregulation and Heat Loss Prevention After Birth and During Neonatal Intensive-Care Unit Stabilization of Extremely Low-Birthweight InfantsJOURNAL OF OBSTETRIC, GYNECOLOGIC & NEONATAL NURSING, Issue 3 2007Robin Knobel Extremely low-birthweight infants have inefficient thermoregulation due to immaturity and may exhibit cold body temperatures after birth and during their first 12 hours of life. Hypothermia in these infants can lead to increased morbidity and mortality. Anecdotal notes made during our recent study revealed extremely low-birthweight infants' temperatures decreased with caregiver procedures such as umbilical line insertion, intubations, obtaining chest x-rays, manipulating intravenous lines, repositioning, suctioning, and taking vital signs during the first 12 hours of life. Therefore, nursing interventions should be undertaken to prevent heat loss during these caregiver procedures. Nurses can improve the thermal environment for extremely low-birthweight infants by prewarming the delivery room and placing the infant in a plastic bag up to the neck during delivery room stabilization to prevent heat loss. JOGNN, 36, 280-287 ; 2007. DOI: 10.1111/J.1552-6909.2007.00149.x [source] Thermoregulation and roost selection by reproductive female big brown bats (Eptesicus fuscus) roosting in rock crevicesJOURNAL OF ZOOLOGY, Issue 3 2003Cori L. Lausen A free-ranging maternity colony of big brown bats Eptesicus fuscus roosting in rock crevices along the South Saskatchewan River in south-eastern Alberta, Canada, was studied to understand better the discrepancy that exists in the literature regarding torpor use by reproductive female bats. Using radio-telemetry, thermoregulatory patterns and roost microclimate were recorded for pregnant, lactating and post-lactating females. Relative torpor use is described in several ways: the proportion of days on which torpor was used, depth, minimum body temperature, time spent in torpor, and a comprehensive torpor unit (degree-min). Pregnant and lactating female E. fuscus used torpor to the same extent overall (degree-min), but pregnant bats used torpor less frequently and with more time in deep torpor. Torpor was used to the greatest extent after weaning (post-lactation). Evidence is presented that the cost:benefit ratio for deep and prolonged periods of torpor may be highest during lactation. Microclimates of rock-crevice roosts mirrored the use of torpor throughout reproduction by bats. Lactation roosts (deeper, larger opening size) were more thermally stable and remained warmer at night compared to the shallow roosts used by pregnant and post-lactating females. It is shown that conclusions about relative use of torpor can differ depending on the units of comparison, necessitating measurement of all aspects of torpor (depth, duration and frequency). Comprehensive measurements, individual-based normothermic temperatures, and a definition of torpor that accounts for all energy savings, allow a more accurate depiction of patterns and facilitates inter-study comparisons. [source] Thermoregulation of the Escherichia coli O157:H7 pO157 ecf operon and lipid A myristoyl transferase activity involves intrinsically curved DNAMOLECULAR MICROBIOLOGY, Issue 2 2004Jang W. Yoon Summary Escherichia coli O157:H7 survives in diverse environments from the ruminant gastrointestinal tract to cool nutrient-dilute water. We hypothesized that the gene regulation required for this flexibility includes intrinsically curved DNA that responds to environmental changes. Three intrinsically curved DNAs were cloned from the E. coli O157:H7 virulence plasmid (pO157), sequenced and designated Bent 1 through Bent 3 (BNT1, BNT2 and BNT3). Compared to BNT1 and BNT3, BNT2 had characteristics typical of intrinsically curved DNA including electrophoretic gel retardation at 4°C, six partially phased adenine:thymine tracts and transcriptional activation. BNT2::lacZ operon fusions showed that BNT2 activated transcription at 24°C compared to 37°C and was partially repressed by a bacterial nucleoid-associated protein H-NS. BNT2 regulated the E. coli attaching and effacing gene-positive conserved fragments 1,4 (ecf1,4) that are conserved in Shiga toxin-producing E. coli associated with human disease. Experimental analyses showed that ecf1,4 formed an operon. ecf1, 2 and 3 encoded putative proteins associated with bacterial surface polysaccharide biosynthesis and invasion and ecf4 complemented a chromosomal deletion of lpxM encoding lipid A myristoyl transferase. Mass spectrometric analysis of lipid A from ecf and lpxM single and double mutants showed that myristoylation was altered at lower temperature. [source] Temperature perception and nociceptionDEVELOPMENTAL NEUROBIOLOGY, Issue 1 2004Barry G. Green Abstract The specificity theory of somesthesis holds that perceptions of warmth, cold, and pain are served by separate senses. Although no longer accepted in all its details, the theory's basic assumptions of anatomical and functional specificity have remained guiding principles in research on temperature perception and its relationship to pain. This article reviews the response characteristics of thermoreceptors, temperature-sensitive nociceptors, and their associated pathways in the context of old and new perceptual phenomena, most of which cannot be satisfactorily explained by the specificity theory. The evidence indicates that throughout most of the perceptual range, temperature sensitivity depends upon coactivation of, and interactions among, thermal and nociceptive pathways that are composed of both specific "labeled lines" and nonspecific, multimodal fibers. Adding to this complexity is evidence that tactile stimulation can influence the way in which thermal stimulation is perceived. It is argued that thermoreception is best defined as a functional subsystem of somesthesis that serves the very different and sometimes conflicting demands of thermoregulation, protection from thermal injury, and haptic perception. © 2004 Wiley Periodicals, Inc. J Neurobiol 61: 13,29, 2004 [source] Foot temperature in diabetic polyneuropathy: innocent bystander or unrecognized accomplice?DIABETIC MEDICINE, Issue 3 2005S. B. Rutkove Abstract Aim To explore mechanisms by which temperature could influence the pathogenesis and symptoms of diabetic polyneuropathy. Methods We conducted a literature review attempting to identify mechanisms by which diabetic polyneuropathy could be affected by temperature. Results Cooling can theoretically hasten the progression of diabetic polyneuropathy through several different mechanisms. Specifically, cooling can enhance neuronal ischaemia, increase formation of reactive oxygen species, slow axonal transport, increase protein kinase C activity, and interfere with immune function. Short-term temperature fluctuations (both warming and cooling) can initiate and exacerbate neuropathic pain by causing neuronal hyperexcitability and functional deafferentation. Although normal fluctuations of distal extremity temperature may be sufficient for these effects, impaired thermoregulation may make the distal extremities more susceptible to temperature extremes. Eventually, a ,vicious cycle' may ensue, resulting in neuronal deterioration with further disruption of temperature regulation. Limited epidemiological data suggest a higher prevalence of diabetic polyneuropathy in populations living in colder locations, supporting our hypothesis. Conclusions Variations in foot temperature may play an important but as yet unrecognized role in the development and symptoms of diabetic polyneuropathy. Further basic and clinical research exploring this concept could help elucidate the natural history of diabetic polyneuropathy and lead to novel therapeutic strategies. [source] Effects of temperature and elevation on habitat use by a rare mountain butterfly: implications for species responses to climate changeECOLOGICAL ENTOMOLOGY, Issue 4 2009SARAH ASHTON Abstract 1.,The present study used the mountain specialist butterfly Parnassius apollo as a model system to investigate how climate change may alter habitat requirements for species at their warm range margins. 2.,Larval habitat use was recorded in six P. apollo populations over a 700 m elevation gradient in the Sierra de Guadarrama (central Spain). Larvae used four potential host species (Sedum spp.) growing in open areas amongst shrubs. 3.,Parnassius apollo host-plant and habitat use changed as elevation increased: the primary host shifted from Sedum amplexicaule to Sedum brevifolium, and larvae selected more open microhabitats (increased bare ground and dead vegetation, reduced vegetation height and shrub cover), suggesting that hotter microhabitats are used in cooler environments. 4.,Larval microhabitat selection was significantly related to ambient temperature. At temperatures lower than 27 °C, larvae occupied open microhabitats that were warmer than ambient temperature, versus more shaded microhabitats that were cooler than ambient conditions when temperature was higher than 27 °C. 5.,Elevational changes in phenology influenced the temperatures experienced by larvae, and could affect local host-plant favourability. 6.,Habitat heterogeneity appears to play an important role in P. apollo larval thermoregulation, and may become increasingly important in buffering populations of this and other insect species against climatic variation. [source] Thermal biology of the meadow grasshopper, Chorthippus parallelus, and the implications for resistance to diseaseECOLOGICAL ENTOMOLOGY, Issue 6 2005Simon Springate Abstract., 1.,The thermal biology of the meadow grasshopper, Chorthippus parallelus, a common, habitat generalist acridid species found in the U.K., was characterised and the influence of thermoregulatory behaviour for resistance against a temperate (Beauveria bassiana) and tropical (Metarhizium anisopliae var. acridum) fungal pathogen was determined. 2.,Chorthippus parallelus was found to be an active behavioural thermoregulator, with a preferred temperature range of 32,35 °C. 3.,Both pathogens proved lethal to fifth instar and adult grasshoppers. No evidence of behavioural fever in response to infection by either pathogen was found, but normal thermoregulation was found to reduce virulence and spore production of B. bassiana. Normal thermoregulation did not appear to affect M. anisopliae var. acridum. 4.,These results suggest that the effects of temperature on host resistance depend on the thermal sensitivity of the pathogen and, in this case, derive from direct effects of temperature on pathogen growth rather than indirect effects mediated by host immune response. 5.,The implications for possible risks of exotic pathogens and influence of climate change are discussed. [source] Microgeographical variation in thermal preference by an amphibianECOLOGY LETTERS, Issue 5 2004L. Kealoha Freidenburg Abstract Ectotherms use behaviour to buffer effects of temperature on growth, development and survival. While behavioural thermoregulation is widely reported, localized adaptation of thermal preference is poorly documented. Larval amphibians live in wetlands ranging from entirely open to heavily shaded by vegetation. We hypothesized that populations undergo localized selection leading to countergradient patterns of thermal preference behaviour. Specifically, we predicted that wood frog (Rana sylvatica) larvae from closed canopy ponds would be more strongly temperature selective and would prefer higher temperatures than conspecifics from populations found in open canopy ponds. In a study of six breeding ponds in north-eastern Connecticut, USA, these predictions were upheld. The countergradient, microgeographical variation in thermal preference documented here implies that wood frog populations may have diverged rapidly in the face of contrasting selection pressures. Rapid, behaviourally mediated responses to changing thermal environments have important implications for understanding population responses to climate change. [source] Temperature and Ca2+ ion as modulators in cellular immunity of the Sunn pest Eurygaster integriceps Puton (Heteroptera: Scutelleridae)ENTOMOLOGICAL RESEARCH, Issue 6 2009Arash ZIBAEE Abstract Environmental conditions in addition to divalent cations may affect the interactions between pathogens and insects. Elucidation of factors which modulate insect immune responses could be a significant part of investigations in this area. In this study, adults of Eurygaster integriceps, as the destructive pest of wheat, were kept at different temperatures in addition to injection with different concentrations of Ca2+ to find the effect on cellular immune reactions against Beauveria bassiana. Results showed that total and differentiate hemocyte numbers, nodule formation and phenoloxidase activity increased with elevation of temperature so that the higher values were obtained at 30 and 40°C at various intervals. Higher concentrations of Ca2+ ion (5 mM) caused an increase in plasmatocyte length and width especially after 60 min. Similar results were observed for nodule formation and phenoloxidase activity of E. integriceps adults after injection by B. bassiana spores and phenoloxidase activity. It is clear from the current study that thermoregulation and Ca2+ ion can positively affect the hemocyte numbers especially plasmatocytes and granulocytes, nodule formation and phenoloxidase activity in E. integriceps. The understanding of modulators of the insect immune response may directly influence novel approaches to obtain safe and effective biological control agents. [source] Effects of fungicides on thyroid function, metabolism, and thermoregulation in cotton rats,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2001Thomas E. Tomasi Abstract Among the myriad of recent studies on endocrine-disrupting chemicals, relatively few involve thyroid disruption, and most of these address exposure/disruption during embryonic life. Of those involving adult vertebrates, the endpoints examined are thyroid measurements. Even though thyroid disruption could potentially interfere with energy metabolism and thermoregulation such that over-winter survival might be compromised, the possible energetic consequences of these thyroid perturbations have not been investigated. We assessed thyroid function and measured resting metabolic rates of cotton rats chronically exposed to the fungicides vinclozolin or mancozeb. In addition, we measured norepinephrine-induced nonshivering thermogenesis and cold-induced thermogenesis and then cold-acclimated the mancozeb animals. Although thyroid hormone concentrations generally decreased, this was compensated for by an increase in thyroxine turnover (vinclozolin study only) such that thyroxine utilization rate was not different. In addition, there was no difference between the treated and control animals in any of the metabolic parameters measured. It is concluded that wild rodents exposed to these compounds are not energetically compromised. [source] COEVOLUTION OF COLOR PATTERN AND THERMOREGULATORY BEHAVIOR IN POLYMORPHIC PYGMY GRASSHOPPERS TETRIX UNDULATAEVOLUTION, Issue 2 2002Anders Forsman Abstract Ectothermic organisms, such as insects and reptiles, rely on external heat sources to control body temperature and possess physiological and behavioral traits that are temperature dependent. It has therefore been hypothesised that differences in body temperature resulting from phenotypic properties, such as color pattern, may translate into selection against thermally inferior phenotypes. We tested for costs and benefits of pale versus dark coloration by comparing the behaviors (i.e., basking duration and bouts) of pygmy grasshopper (Tetrix undulata) individuals exposed to experimental situations imposing a trade-off between temperature regulation and feeding. We used pairs consisting of two full-siblings of the same sex that represented different (genetically coded) color morphs but had shared identical conditions from the time of fertilization. Our results revealed significant differences in behavioral thermoregulation between dark and pale individuals in females, but not in males. Pale females spent more time feeding than dark females, regardless of whether feeding was associated with a risk of either hypothermia or overheating. In contrast, only minor differences in behavior (if any) were evident between individuals that belonged to the same color morph but had been painted black or gray to increase and decrease their heating rates. This suggests that the behavioral differences between individuals belonging to different color morphs are genetically determined, rather than simply reflecting a response to different heating rates. To test for effects of acclimation on behaviors, we used pairs of individuals that had been reared from hatchlings to adults under controlled conditions in either low or high temperature. The thermal regime experienced during rearing had little effect on behaviors during the experiments reported above, but significantly influenced the body temperatures selected in a laboratory thermal gradient. In females (but not in males) preferred body temperature also varied among individuals born to mothers belonging to different color morphs, suggesting that a genetic correlation exists between color pattern and temperature preferences. Collectively, these findings, at least in females, are consistent with the hypothesis of multiple-trait coevolution and suggest that the different color morphs represent alternative evolutionary strategies. [source] Functional skin adaptation in infancy , almost complete but not fully competentEXPERIMENTAL DERMATOLOGY, Issue 6 2010Joachim W. Fluhr Please cite this paper as: Functional skin adaptation in infancy , almost complete but not fully competent. Experimental Dermatology 2010; 19: 483,492. Abstract:, Early postnatal life is a period of active functional reorganization and cutaneous physiological adaptation to the extrauterine environment. Skin as the outermost organ of mammalians is endowed of multiple functions such as protection, secretion, absorption and thermoregulation. Birth stimulates the epidermal barrier maturation and the skin surface acidification especially in premature infants. In full-term infants the developed stratum corneum accomplishes competent barrier function, in contrast to prematures. Complete barrier maturation in preterm infants is fulfilled by 2,4 weeks of the postnatal life. However, in preterms with 23,25 weeks gestational age this process takes longer. Versatile regulatory mechanisms, namely skin surface acidity, calcium ion gradient and nuclear hormone receptors/ligands are interrelated in the complex postnatal newborn adaptation. The skin of newborns is adjusting quickly to the challenging environmental conditions of the postpartum. However, certain functions, for example, microcirculation, continue to develop even beyond the neonatal period, that is, up to the age of 14,17 weeks. Different environmental factors (for instance, dry and cold climate, diapers and cosmetic care procedures) influence the postnatal development of skin functional parameters such as stratum corneum hydration and the permeability barrier especially in premature infants. The aim of this article is to summarize the current knowledge on skin physiology in newborn and infants with a practical approach and to discuss the possible clinical consequences. This review offers the readership a critical and practical overview of skin physiology in newborns and infants. It emphasizes possible new research fields in neonatal and infantile skin physiology. [source] Differences in the skin peptides of the male and female Australian tree frog Litoria splendidaFEBS JOURNAL, Issue 1 2000The discovery of the aquatic male sex pheromone splendipherin, a new antibiotic peptide caerin 1.10, together with Phe8 caerulein The skin secretions of female and male Litoria splendida have been monitored monthly over a three-year period using HPLC and electrospray mass spectrometry. Two minor peptides are present only in the skin secretion of the male. The first of these is the female-attracting aquatic male sex pheromone that we have named splendipherin, a 25 amino acid peptide (GLVSSIGKALGGLLADVVKSKGQPA-OH). This pheromone constitutes about 1% of the total skin peptides during the breeding season (January to March), dropping to about 0.1% during the period June to November. Splendipherin attracts the female in water at a concentration of 10,11,10,9 m, and is species specific. The second peptide is a wide-spectrum antibiotic of the caerin 1 group, a 25 residue peptide (GLLSVLGSVAKHVLPHVVPVIAEKL-NH2) named caerin 1.10. The neuropeptides of L. splendida are also seasonally variable, the change identical for both the female and male. During the period October to March, the sole neuropeptide present in skin secretions is caerulein [pEQDY(SO3)TGWMDF-NH2]; this is active on smooth muscle and is also an analgaesic. During the southern winter (June to September), more than half of the caerulein is hydrolysed to [pEQDYTGWMDF-NH2], a peptide that shows no smooth muscle activity. In place of caerulein, a new peptide, Phe8 caerulein [pEQDY(SO3)TGWFDF-NH2], becomes a major component of the skin secretion. Perhaps this seasonal change is involved in thermoregulation, that is, with the initiation and maintenance of the inactive (hibernation) phase of the animal. [source] Adaptations of amphibious fish for surviving life out of waterFISH AND FISHERIES, Issue 3 2005Martin D J Sayer Abstract There are a small number of fish species, both marine and freshwater, that exhibit a truly amphibious habit that includes periods of aerial exposure. The duration of emersion is reflected in the level of physical and physiological adaptation to an amphibious lifestyle. Fish that are only briefly out of water retain predominantly aquatic attributes whereas there are semi-terrestrial species that are highly adapted to prolonged periods in the aerial habitat. Desiccation is the main stressor for amphibious fish and it cannot be prevented by physiological means. Instead, amphibious fish resist excessive water loss by means of cutaneous modification and behavioural response. The more terrestrially adapted fish species can tolerate considerable water loss and may employ evaporation to aid thermoregulation. The amphibious habit is limited to fish species that can respire aerially. Aerial respiration is usually achieved through modification to existing aquatic pathways. Freshwater air-breathers may respire via the skin or gills but some also have specialized branchial diverticula. Marine species utilize a range of adaptations that may include modified gills, specialized buccopharyngeal epithelia, the intestine and the skin. Areas of enhanced respiratory activity are typified by increased vascularization that permits enhanced perfusion during aerial exposure. As with other adaptations the mode of nitrogenous elimination is related to the typical durations of emersion experienced by the fish. Intertidal species exposed on a regular cycle, and which may retain some contact with water, tend to remain ammoniotelic while reducing excretion rates in order to prevent excessive water loss. Amphibious fish that inhabit environments where emersion is less predictable than the intertidal, can store nitrogen during the state of emersion with some conversion to ureotelism or have been shown to tolerate high ammonia levels in the blood. Finally, the more amphibious fish are more adapted to moving on land and seeing in air. Structural modifications to the pectoral, pelvic, dorsal and anal fins, combined with a well-developed musculature permit effective support and movement on land. For vision in air, there is a general trend for fish to possess close-set, moveable, protruberant eyes set high on the head with various physical adaptations to the structure of the eye to allow for accurate vision in both air and water. [source] Nursing and midwifery management of hypoglycaemia in healthy term neonatesINTERNATIONAL JOURNAL OF EVIDENCE BASED HEALTHCARE, Issue 7 2005Vivien Hewitt BSc(Hons) GradDipLib Executive summary Objectives The primary objective of this review was to determine the best available evidence for maintenance of euglycaemia, in healthy term neonates, and the management of asymptomatic hypoglycaemia in otherwise healthy term neonates. Inclusion criteria Types of studies The review included any relevant published or unpublished studies undertaken between 1995 and 2004. Studies that focus on the diagnostic accuracy of point-of-care devices for blood glucose screening and/or monitoring in the neonate were initially included as a subgroup of this review. However, the technical nature and complexity of the statistical information published in diagnostic studies retrieved during the literature search stage, as well as the considerable volume of published research in this area, suggested that it would be more feasible to analyse diagnostic studies in a separate systematic review. Types of participants The review focused on studies that included healthy term (37- to 42-week gestation) appropriate size for gestational age neonates in the first 72 h after birth. Exclusions ,,preterm or small for gestational age newborns; ,,term neonates with a diagnosed medical or surgical condition, congenital or otherwise; ,,babies of diabetic mothers; ,,neonates with symptomatic hypoglycaemia; ,,large for gestational age neonates (as significant proportion are of diabetic mothers). Types of intervention All interventions that fell within the scope of practice of a midwife/nurse were included: ,,type (breast or breast milk substitutes), amount and/or timing of feeds, for example, initiation of feeding, and frequency; ,,regulation of body temperature; ,,monitoring (including screening) of neonates, including blood or plasma glucose levels and signs and symptoms of hypoglycaemia. Interventions that required initiation by a medical practitioner were excluded from the review. Types of outcome measures Outcomes that were of interest included: ,,occurrence of hypoglycaemia; ,,re-establishment and maintenance of blood or plasma glucose levels at or above set threshold (as defined by the particular study); ,,successful breast-feeding; ,,developmental outcomes. Types of research designs The review initially focused on randomised controlled trials reported from 1995 to 2004. Insufficient randomised controlled trials were identified and the review was expanded to include additional cohort and cross-sectional studies for possible inclusion in a narrative summary. Search strategy The major electronic databases, including MEDLINE/PubMed, CINAHL, EMBASE, LILACS, Cochrane Library, etc., were searched using accepted search techniques to identify relevant published and unpublished studies undertaken between 1995 and 2004. Efforts were made to locate any relevant unpublished materials, such as conference papers, research reports and dissertations. Printed journals were hand-searched and reference lists checked for potentially useful research. The year 1995 was selected as the starting point in order to identify any research that had not been included in the World Health Organisation review, which covered literature published up to 1996. The search was not limited to English language studies. Assessment of quality Three primary reviewers conducted the review assisted by a review panel. The review panel was comprised of nine nurses with expertise in neonatal care drawn from senior staff in several metropolitan neonatal units and education programs. Authorship of journal articles was not concealed from the reviewers. Methodological quality of each study that met the inclusion criteria was assessed by two reviewers, using a quality assessment checklist developed for the review. Disagreements between reviewers were resolved through discussion or with the assistance of a third reviewer. Data extraction and analysis Two reviewers used a data extraction form to independently extract data relating to the study design, setting and participants; study focus and intervention(s); and measurements and outcomes. As only one relevant randomised controlled trial was found, a meta-analysis could not be conducted nor tables constructed to illustrate comparisons between studies. Instead, the findings were summarised by a narrative identifying any relevant findings that emerged from the data. Results Seven studies met the inclusion criteria for the objective of this systematic review. The review provided information on the effectiveness of three categories of intervention , type of feeds, timing of feeds and thermoregulation on two of the outcome measures identified in the review protocol , prevention of hypoglycaemia, and re-establishment and maintenance of blood or plasma glucose levels above the set threshold (as determined by the particular study). There was no evidence available on which to base conclusions for effectiveness of monitoring or developmental outcomes, and insufficient evidence for breast-feeding success. Given that only a narrative review was possible, the findings of this review should be interpreted with caution. The findings suggest that the incidence of hypoglycaemia in healthy, breast-fed term infants of appropriate size for gestational age is uncommon and routine screening of these infants is not indicated. The method and timing of early feeding has little or no influence on the neonatal blood glucose measurement at 1 h in normal term babies. In healthy, breast-fed term infants the initiation and timing of feeds in the first 6 h of life has no significant influence on plasma glucose levels. The colostrum of primiparous mothers provides sufficient nutrition for the infant in the first 24 h after birth, and supplemental feeds or extra water is unnecessary. Skin-to-skin contact appears to provide an optimal environment for fetal to neonatal adaptation after birth and can help to maintain body temperature and adequate blood glucose levels in healthy term newborn infants, as well as providing an ideal opportunity to establish early bonding behaviours. Implications for practice The seven studies analysed in this review confirm the World Health Organisation's first three recommendations for prevention and management of asymptomatic hypoglycaemia, namely: 1Early and exclusive breast-feeding is safe to meet the nutritional needs of healthy term newborns worldwide. 2Healthy term newborns that are breast-fed on demand need not have their blood glucose routinely checked and need no supplementary foods or fluids. 3Healthy term newborns do not develop ,symptomatic' hypoglycaemia as a result of simple underfeeding. If an infant develops signs suggesting hypoglycaemia, look for an underlying condition. Detection and treatment of the cause are as important as correction of the blood glucose level. If there are any concerns that the newborn infant might be hypoglycaemic it should be given another feed. Given the importance of thermoregulation, skin-to-skin contact should be promoted and ,kangaroo care' encouraged in the first 24 h after birth. While it is important to main the infant's body temperature care should be taken to ensure that the child does not become overheated. [source] The structural design of the bat wing web and its possible role in gas exchangeJOURNAL OF ANATOMY, Issue 6 2007Andrew N. Makanya Abstract The structure of the skin in the epauletted fruit bat (Epomophorus wahlbergi) wing and body trunk was studied with a view to understanding possible adaptations for gas metabolism and thermoregulation. In addition, gas exchange measurements were performed using a respirometer designed for the purpose. The body skin had an epidermis, a dermis with hair follicles and sweat glands and a fat-laden hypodermis. In contrast, the wing web skin was made up of a thin bilayered epidermis separated by a connective tissue core with collagen and elastic fibres and was devoid of hair follicles and sweat glands. The wings spanned 18,24 cm each, with about 753 cm2 of surface exposed to air. The body skin epidermis was thick (61 ± 3 µm, SEM), the stratum corneum alone taking a third of it (21 ± 3 µm). In contrast, the wing web skin epidermis was thinner at 9.8 ± 0.7 µm, with a stratum corneum measuring 4.1 ± 0.3 µm (41%). The wing capillaries in the wing web skin ran in the middle of the connective tissue core, with a resultant surface-capillary diffusion distance of 26.8 ± 3.2 µm. The rate of oxygen consumption (V,O2) of the wings alone and of the whole animal measured under light anaesthesia at ambient temperatures of 24 ºC and 33 ºC, averaged 6% and 10% of the total, respectively. Rate of carbon dioxide production had similar values. The membrane diffusing capacity for the wing web was estimated to be 0.019 ml O2 min,1 mmHg,1. We conclude that in Epomophorus wahlbergi, the wing web has structural modifications that permit a substantial contribution to the total gas exchange. [source] Lizard community structure along environmental gradientsJOURNAL OF ANIMAL ECOLOGY, Issue 2 2010Lauren B. Buckley Summary 1. ,How the total number of individuals in a community is divided among its species is governed by both the distribution of species along landscape-scale environmental gradients and by local resource partitioning. In vertebrate ectotherms, abiotic environmental conditions may constrain geographic distributions more strongly than local population densities due to thermal constraints on resource acquisition and due to behavioural thermoregulation. 2. ,We investigate whether local density and species richness are decoupled for lizard communities within the Southwest US by comparing 18 species-abundance distributions. 3. ,While species richness decreases strongly with decreasing temperature, there is no significant relationship between temperature or resource availability (net primary productivity) and the total number of individuals within a community. Consequently, in more species-rich communities species have lower mean abundances. 4. ,This suggestion that lizard species richness is not a function of an area's capacity to support more individuals questions for this group species diversity theories based on this assumption. [source] Landscape complementation and food limitation of large herbivores: habitat-related constraints on the foraging efficiency of wild pigsJOURNAL OF ANIMAL ECOLOGY, Issue 1 2003David Choquenot Summary 1The effect that the proximity of habitats containing essential resources has on animal abundance at large spatial scales is called landscape complementation. Landscape complementation can influence interaction between large herbivores and their food resources where the proximity of habitats containing essential resources constrains their foraging or demographic efficiency. 2We tested the effect that the proximity of a thermal refuge (riverine woodlands) had on interaction between wild pigs and their food resources (pasture). The numerical response of pigs (Sus scrofa L.) (estimated as r quarter,1) to pasture biomass was contrasted between four sites that were progressively more isolated from a major floodplain containing extensive areas of riverine woodland. To test whether proximity to riverine woodlands affected the numerical response of pigs through a constraint on foraging efficiency, we contrasted the numerical response of pigs between the four areas as pasture biomass declined. To test whether pigs exploited riverine woodlands primarily as a thermal refuge, we contrasted the numerical response of pigs between the four areas in different seasons. 3We found that although pasture biomass was similar in the four areas, r was lower than expected for given pasture biomass on the two areas further away from riverine woodlands. We also found that while the effect that proximity to riverine woodlands had on the numerical response of pigs became more pronounced when pasture biomass was low, it was not significantly affected by season. 4These results suggest that the need to access riverine woodlands compromises the foraging efficiency of wild pigs when the distance to this habitat is relatively high, but that the need to access this habitat may not be purely related to thermoregulation. 5We developed a simple mechanistic model that allows the effects of landscape complementation on herbivore foraging and demographic efficiency to be estimated, and used the model to predict the effect that proximity to riverine woodlands would have on variation in pig density. The model suggests that wild pigs cannot persist in areas more then 10 km from extensive riverine woodlands, unless those areas are periodically re-colonized. This suggests that at the margin of their range around inland river systems, given locations that can be occupied by wild pigs will vary temporally between being sources, pseudosinks and sinks. [source] An experimental test of the link between foraging, habitat selection and thermoregulation in black rat snakes Elaphe obsoleta obsoletaJOURNAL OF ANIMAL ECOLOGY, Issue 6 2001Gabriel Blouin-Demers Summary 1Most physiological processes are temperature-dependent. Thus, for ectotherms, behavioural control of body temperatures directly affects their physiology. Ectotherms thermoregulate by adjusting habitat use and therefore thermoregulation is probably the single most important proximate factor influencing habitat use of terrestrial reptiles, at least in temperate climates. 2Snakes have been shown to raise their body temperature following feeding in a laboratory thermal gradient, presumably to enhance digestion. This experiment was exported to the field to explore the link between feeding, habitat selection and thermoregulation in free-ranging snakes. 3Experimental feeding was conducted in the laboratory and in the field on black rat snakes (Elaphe obsoleta obsoleta) that had temperature-sensitive radio-transmitters surgically implanted. 4Snakes had higher mean body temperatures following feeding than prior to feeding in a laboratory thermal gradient. 5Some, but not all evidence, indicated that black rat snakes increased their mean body temperature following feeding in the field. Indices of thermoregulation indicated that the snakes thermoregulated more carefully and more effectively after they had eaten. 6Forest edges provided the best opportunities for thermoregulation in the study area. Black rat snakes were less likely to move following feeding when fed in edges than when fed in the forest and were more likely to be found in edges following feeding, whether they had been fed in the forest or in an edge. 7Results of this study and one previous study suggest that thermoregulatory behaviour of snakes following feeding in the laboratory is a reliable predictor of their behaviour in the field. A review of 13 studies of the thermoregulatory behaviour of snakes following feeding in the laboratory revealed that not all species behave similarly. However, the quality and number of studies currently available is not adequate for testing hypotheses about which species should change thermoregulatory behaviour in response to eating and which should not. [source] Raised thermoregulatory costs at exposed song posts increase the energetic cost of singing for willow warblers Phylloscopus trochilusJOURNAL OF AVIAN BIOLOGY, Issue 4 2005Sally Ward Sexually selected displays, such as bird song, are expected to be costly. We examined a novel potential cost to bird song: whether a less favourable microclimate at exposed song posts would be predicted to raise metabolic rate. We measured the microclimate and height at which willow warblers Phylloscopus trochilus sang and foraged. Song posts were higher than foraging sites. The wind speed was 0.6±0.3 ms,1 greater at song posts (mean±SD, N=12 birds). Song rate and song post selection were not influenced consistently by temperature or wind speed, but the birds sang from lower positions on one particularly windy day. This may have resulted from difficulty in holding on to exposed branches in windy conditions rather than a thermoregulatory constraint. The results suggest that the extra thermoregulatory costs at song posts would increase metabolic rate by an average of 10±4% and a maximum of 25±8% (N=12 birds) relative to birds singing at foraging sites. We estimated that metabolic rate would be 3,8% greater during singing than during quiet respiration because of heat and evaporative water loss in exhaled gases. The combined energy requirements for sound production, thermoregulation at exposed song posts and additional heat loss in exhaled air could increase the metabolic rate of willow warblers by an average of 14,23%, and a maximum of 42,63%, during singing. The energetic cost of singing may thus be much greater for birds in a cold, windy environment than for birds singing in laboratory conditions. [source] The role of water abundance, thermoregulation, perceived predation risk and interference competition in water access by African herbivoresAFRICAN JOURNAL OF ECOLOGY, Issue 3 2008Marion Valeix Abstract In African savannas, surface water can become limiting and an understanding of how animals address the trade-offs between different constraints to access this resource is needed. Here, we describe water access by ten African herbivore species in Hwange National Park, Zimbabwe, and we explore four possible determinants of the observed behaviours: water abundance, thermoregulation, perceived predation risk and interference competition. On average, herbivores were observed to drink in 80% of visits to a waterhole. The probability of drinking was higher in 2003 (474 mm) than in 2004 (770 mm), and at the end of the dry season than at its beginning. For larger species, this probability may also be related to risks of interference competition with elephants or other herbivores. For smaller species, this probability may also be related to the perceived risk of predation. We also investigate the time spent accessing water to drink. The influence of herd size and the presence of young on the time spent accessing water for most species suggests that perceived predation risk plays a role. Thermoregulation also affects this time: during the hottest periods, herbivores spend less time in open areas, unless when wind is strong, probably owing to evapotranspired heat loss. Résumé Dans les savanes africaines, l'eau de surface disponible peut devenir un facteur limitant et il est nécessaire de comprendre comment les animaux agissent face aux différentes contraintes que pose l'accès à cette ressource. Nous décrivons ici l'accès à l'eau de dix herbivores africains du Parc National de Hwange, au Zimbabwe, et nous explorons quatre facteurs qui sont peut-être déterminants dans les comportements observés: l'abondance de l'eau, la thermorégulation, le risque de prédation ressenti et la compétition/ interférence. En moyenne, on a observé que les herbivores buvaient lors de 80% de leurs visites au point d'eau. La probabilité qu'ils boivent étai plus forte en 2003 (474 mm) qu'en 2004 (770 mm), et à la fin de la saison sèche qu'au début. Pour les plus grandes espèces, cette probabilité pourrait aussi être liée aux risques de compétition par interférence avec les éléphants ou d'autres herbivores. Pour les plus petites espèces, cette probabilité pourrait aussi être liée au risque de prédation ressenti. Nous avons aussi étudié le temps passéà se rendre au point d'eau pour y boire. L'influence de la taille du groupe et de la présence de jeunes sur le temps pris par la plupart des espèces pour se rendre au point d'eau laisse penser que la perception du risque de prédation joue un rôle. La thermorégulation affecte aussi cette durée: pendant les périodes les plus chaudes, les herbivores passent moins de temps dans les espaces ouverts, sauf si le vent est fort, probablement à cause de la perte de chaleur par évapotranspiration. [source] Glomus Coccygeum: Report of a CaseJOURNAL OF CUTANEOUS PATHOLOGY, Issue 1 2005A. Rahemtullah The glomus coccygeum is a vestigial structure related to the canals of Sucquet-Hoyer, an arteriovenous anastomosis surrounded by glomus cells derived from modified smooth muscle and involved in thermoregulation. It is an incidental finding in specimens from the sacral area and may represent a diagnostic challenge to the unaware observer. We present a case of a glomus coccygeum, presenting as a 1.5 mm structure adjacent to a typical pilonidal cyst excised from a 7-month-old boy, that was the subject of a second opinion consultation. The lesion showed small to medium sized clusters of predominantly epithelioid cells with moderate amounts of clear to eosinophilic cytoplasm, intercellular borders and plump, round nuclei with fine chromatin. These cells were closely associated with small vascular channels and nerves. Immunohistochemistry revealed that the epithelioid cells expressed vimentin, muscle-specific actin, neuron-specific enolase, and S-100 protein, were weakly positive for smooth muscle actin, and negative for desmin, synaptophysin and chromogranin. The endothelial cells of the vascular channels were antibody CD31 positive. Recognition of the histological features of glomus coccygeum is important to avoid confusion with glomus tumor and neural or smooth muscle neoplasms in the sacral area. [source] Melanic through nature or nurture: genetic polymorphism and phenotypic plasticity in Harmonia axyridisJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 8 2010L. J. MICHIE Abstract Individuals can adapt to heterogeneity in their environment through either local adaptation or phenotypic plasticity. Colour forms of the ladybird Harmonia axyridis are a classic example of local adaptation, in which the frequency of melanic forms varies greatly between populations. In some populations, there are also large seasonal changes in allele frequency, with melanism being costly in summer and beneficial in winter. We report that the non-melanic morph of H. axyridis dramatically increases its degree of melanization at cold temperatures. Furthermore, there is genetic variation in reaction norms, with different families responding to temperature in different ways. Variation at different spatial and temporal scales appears to have selected for either genetic or phenotypically plastic adaptations, which may be important in thermoregulation. As melanism is known to have a large effect on fitness in H. axyridis, this plasticity of melanization may have hastened its spread as an invasive species. [source] Altitudinal variation in behavioural thermoregulation: local adaptation vs. plasticity in California grasshoppersJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2005J. SAMIETZ Abstract We investigated the adaptive significance of behavioural thermoregulation in univoltine populations of the grasshopper Melanoplus sanguinipes along an altitudinal gradient in California using laboratory tests of animals raised under different temperatures. Trials consisted of continuous body temperature measurements with semi-implanted microprobes in a test arena, and observation and simultaneous recording of behavioural responses. These responses included mobility, basking and orientation of the body axes (aspect angle) towards a radiation source. Mobility and basking are determined by the altitudinal origin of the parental generation and not by the temperature treatments. With increasing altitude, individuals tend increasingly to raise body temperatures via mobility and increased basking. In contrast, body orientation towards the radiation source is influenced by the temperature treatments but not by the altitude of origin. Individuals experiencing higher temperatures during rearing show a lower tendency to lateral flanking. We conclude that body orientation responses are not adapted locally. In contrast other components of the behavioural syndrome that increase body temperature, such as mobility and basking, are adaptive in response to local selection pressure. The thermoregulatory syndrome of these grasshoppers is an important contribution to life-history adaptations that appropriately match season lengths. [source] Ecological diversification in a group of Indomalayan pitvipers (Trimeresurus): convergence in taxonomically important traits has implications for species identificationJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2004K. L. Sanders Abstract We analyse molecular and phenotypic evolution in a group of taxonomically problematic Indomalayan pitvipers, the Trimeresurus sumatranus group. Mitochondrial DNA sequencing provides a well-resolved phylogeny, with each species representing a distinct lineage. Multivariate morphological analysis reveals a high level of phenotypic differentiation, which is congruent between the sexes but does not reflect phylogenetic history. An adaptive explanation for the observed pattern of differentiation is supported by independent contrasts analysis, which shows significant correlations between current ecology and the characters that most account for the variation between taxa, including those that are presently used to identify the species. Reduced precipitation and altitude, and increased temperature, are correlated with higher numbers of scales on the head, body and tail. It is hypothesized that scale number plays an important role in heat and water exchange by influencing the area of exposed of interstitial skin, and that colour pattern variation reflects selection pressures involving camouflage and thermoregulation. Ecological convergence in traits used for classification is found to have important implications for species identification where taxa are distributed over varying environments. [source] Behavioural thermoregulation in two freshwater fish speciesJOURNAL OF FISH BIOLOGY, Issue 10 2010A. J. W. Ward In the presence of a vertical thermal gradient, juvenile three-spined sticklebacks Gasterosteus aculeatus and minnows Phoxinus phoxinus positioned themselves higher in the water column compared with adult conspecifics. This result was consistent regardless of whether age cohorts were tested separately or together. Furthermore, juveniles but not adult fishes positioned themselves higher in water column in the presence of a thermal gradient compared with those in the absence of a thermal gradient. Juvenile G. aculeatus and adult fish of both species did opt to position themselves higher in the water column in the hours immediately following a feeding event relative to their positions in the same gradient when they had not fed. [source] Non-direct homing behaviours by adult Chinook salmon in a large, multi-stock river systemJOURNAL OF FISH BIOLOGY, Issue 1 2008M. L. Keefer Two non-direct homing behaviours, overshoot of natal tributaries and temporary non-natal tributary use, were evaluated for 5150 radio-tagged spring,summer Chinook salmon Oncorhynchus tshawytscha from 40 populations in the large Columbia River system. Over 7 years, 2,44% (mean = 15%) of individuals within each group temporarily entered presumed non-natal tributaries. In addition, many Chinook salmon from lower river tributaries initially travelled 3 to >250 km upstream in the main-stem river beyond confluences with presumed natal tributaries before returning to the natal sites (,overshoot'). Both overshoot and temporary tributary use behaviours declined exponentially with increasing distance from the natal tributary. Non-direct homing also increased later in the season as water temperatures rose and was associated with hatchery origin in some cases. The behaviours may reflect a mix of active searching for olfactory cues from natal sites, behavioural thermoregulation and orientation challenges in a large-river migration corridor transformed by dams and reservoirs. While anadromous salmonid homing is generally accurate and precise, these results indicate that route finding can be non-direct, potentially increasing energetic costs and harvest risks during migration. [source] | |||||||||||||||||||||||||||||||||||||