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1.
Oecologia ; 200(3-4): 349-358, 2022 Dec.
Article in English | MEDLINE | ID: mdl-36175692

ABSTRACT

Wind speed can have multifaceted effects on organisms including altering thermoregulation, locomotion, and sensory reception. While forest cover can substantially reduce wind speed at ground level, it is not known if animals living in forests show any behavioural responses to changes in wind speed. Here, we explored how three boreal forest mammals, a predator and two prey, altered their behaviour in response to average daily wind speeds during winter. We collected accelerometer data to determine wind speed effects on activity patterns and kill rates of free-ranging red squirrels (n = 144), snowshoe hares (n = 101), and Canada lynx (n = 27) in Kluane, Yukon from 2015 to 2018. All 3 species responded to increasing wind speeds by changing the time they were active, but effects were strongest in hares, which reduced daily activity by 25%, and lynx, which increased daily activity by 25%. Lynx also increased the number of feeding events by 40% on windy days. These results highlight that wind speed is an important abiotic variable that can affect behaviour, even in forested environments.


Subject(s)
Hares , Lynx , Sciuridae , Wind , Animals , Ecosystem , Hares/physiology , Lynx/physiology , Predatory Behavior/physiology , Sciuridae/physiology , Taiga
2.
J Community Health ; 46(6): 1204-1212, 2021 Dec.
Article in English | MEDLINE | ID: mdl-34106370

ABSTRACT

Public health crises require individuals, often volunteers, to help minimize disasters. The COVID-19 pandemic required such activation of individuals, but little is known about medical students' preferences of such engagement. We investigated potential variations in medical students' educational preferences, attitudes, and volunteerism during the COVID-19 pandemic based on socio-demographics to better prepare for future activation scenarios. A web-based, anonymous survey of U.S. medical students at a single institution was conducted in May 2020. Across four training year, 518 (68% response rate) students completed the survey. During the pandemic, 42.3% (n = 215) wanted to discontinue in-person clinical experiences, 32.3% (n = 164) wanted to continue, and 25.4% (n = 129) were neutral. There was no gender effect for engagement in volunteer activities or preference to engage in clinical activities during the pandemic. However, second-year (n = 59, 11.6%) and third-year students (n = 58, 11.4%) wanted to continue in-person clinical experiences at a greater proportion than expected, while a small proportion of fourth-year students (n = 17, 3.3%) wanted to continue, χ2(6) = 43.48, p < .001, φ = 0.29. Majority of respondents (n = 287, 55.5%) volunteered in clinical and non-clinical settings. A lower proportion of fourth-year (n = 12, 2.3%) and first-year students (n = 50, 9.7%) volunteered than expected. Likelihood to volunteer during a pandemic varied by gender, training year, and/or prior experience with disaster event depending on the type of volunteer-site setting. Our findings suggest socio-demographic factors may impact medical student engagement and volunteerism during a public health crisis. Educational leadership should be sensitive to such variations and can facilitate volunteer activities that allow student engagement during future pandemics.


Subject(s)
COVID-19 , Students, Medical , Attitude , Humans , Pandemics , SARS-CoV-2 , Volunteers
3.
Comput Struct Biotechnol J ; 19: 852-859, 2021.
Article in English | MEDLINE | ID: mdl-33598100

ABSTRACT

QuPath, originally created at the Centre for Cancer Research & Cell Biology at Queen's University Belfast as part of a research programme in digital pathology (DP) funded by Invest Northern Ireland and Cancer Research UK, is arguably the most wildly used image analysis software program in the world. On the back of the explosion of DP and a need to comprehensively visualise and analyse whole slides images (WSI), QuPath was developed to address the many needs associated with tissue based image analysis; these were several fold and, predominantly, translational in nature: from the requirement to visualise images containing billions of pixels from files several GBs in size, to the demand for high-throughput reproducible analysis, which the paradigm of routine visual pathological assessment continues to struggle to deliver. Resultantly, large-scale biomarker quantification must increasingly be augmented with DP. Here we highlight the impact of the open source Quantitative Pathology & Bioimage Analysis DP system since its inception, by discussing the scope of scientific research in which QuPath has been cited, as the system of choice for researchers.

4.
Ecol Lett ; 23(5): 841-850, 2020 May.
Article in English | MEDLINE | ID: mdl-32189469

ABSTRACT

Animals switch between inactive and active states, simultaneously impacting their energy intake, energy expenditure and predation risk, and collectively defining how they engage with environmental variation and trophic interactions. We assess daily activity responses to long-term variation in temperature, resources and mating opportunities to examine whether individuals choose to be active or inactive according to an optimisation of the relative energetic and reproductive gains each state offers. We show that this simplified behavioural decision approach predicts most activity variation (R2  = 0.83) expressed by free-ranging red squirrels over 4 years, as quantified through accelerometer recordings (489 deployments; 5066 squirrel-days). Recognising activity as a determinant of energetic status, the predictability of activity variation aggregated at a daily scale, and the clear signal that behaviour is environmentally forced through optimisation of gain, provides an integrated approach to examine behavioural variation as an intermediary between environmental variation and energetic, life-history and ecological outcomes.


Subject(s)
Reproduction , Sciuridae , Animals , Energy Metabolism , Predatory Behavior , Seasons
5.
Chemosphere ; 225: 647-658, 2019 Jun.
Article in English | MEDLINE | ID: mdl-30901658

ABSTRACT

DDT remains in use for malaria control in South Africa. We quantified DDTs in aquatic bird eggs from the highly biodiverse northern KwaZulu-Natal, a province of South Africa where DDT has been used for more than 80 years for malaria control. Pelican eggs had the highest ΣDDT concentration (7200 ng/g lipid mass; lm), Little Egret eggs had 6900 ΣDDT lm, African Openbill eggs had 3400 ng/g lm ΣDDT, and White-breasted Cormorant had 2400 ng/g lm. All species had non-significantly different mean concentrations of o,p'-DDT, p,p'-DDT, and ΣDDT, but with significant differences for p,p-DDE, o,p'-DDD, p,p'-DDD, %DDT, %DDD, and %lipid. The thinnest pelican eggshell (0.40 mm) had a ΣDDT concentration of 3300 ng/g lm.; the thickest shell (0.96 mm) had the lowest ΣDDT concentration at 29 ng/g lm; a 58% difference. Linear regressions of concentrations with shell thickness for the pelican eggs were significant for p,p'-DDE and p,p'-DDD, indicating risk of reproductive impairment. Compositional profiles indicate different food webs for the different species. DDT concentrations were lower than from another DDT-sprayed locality in South Africa, possible linked to differences in hydrology and rainfall. We conclude that significant ecotoxic threats associated with DDT remain in this area, and possibly threatens birds from less polluted areas. Our findings suggest continued negative human health and environmental impacts from DDT. There is an urgency to move away from DDT as quickly as possible; alternatively, to implement practices that prevent emissions of DDT to the environment while protecting human life.


Subject(s)
Birds/embryology , DDT/analysis , Egg Shell/chemistry , Eggs/analysis , Animals , DDT/pharmacology , Dichlorodiphenyl Dichloroethylene/analysis , Environmental Pollutants/analysis , Humans , Malaria/prevention & control , South Africa
6.
Mol Psychiatry ; 23(11): 2156-2166, 2018 11.
Article in English | MEDLINE | ID: mdl-28993710

ABSTRACT

Schizophrenia is a neurodevelopmental disorder that affects up to 1% of the general population. Various genes show associations with schizophrenia and a very weak nominal association with the tight junction protein, claudin-5, has previously been identified. Claudin-5 is expressed in endothelial cells forming part of the blood-brain barrier (BBB). Furthermore, schizophrenia occurs in 30% of individuals with 22q11 deletion syndrome (22q11DS), a population who are haploinsufficient for the claudin-5 gene. Here, we show that a variant in the claudin-5 gene is weakly associated with schizophrenia in 22q11DS, leading to 75% less claudin-5 being expressed in endothelial cells. We also show that targeted adeno-associated virus-mediated suppression of claudin-5 in the mouse brain results in localized BBB disruption and behavioural changes. Using an inducible 'knockdown' mouse model, we further link claudin-5 suppression with psychosis through a distinct behavioural phenotype showing impairments in learning and memory, anxiety-like behaviour and sensorimotor gating. In addition, these animals develop seizures and die after 3-4 weeks of claudin-5 suppression, reinforcing the crucial role of claudin-5 in normal neurological function. Finally, we show that anti-psychotic medications dose-dependently increase claudin-5 expression in vitro and in vivo while aberrant, discontinuous expression of claudin-5 in the brains of schizophrenic patients post mortem was observed compared to age-matched controls. Together, these data suggest that BBB disruption may be a modifying factor in the development of schizophrenia and that drugs directly targeting the BBB may offer new therapeutic opportunities for treating this disorder.


Subject(s)
Claudin-5/genetics , Claudin-5/physiology , Schizophrenia/metabolism , 22q11 Deletion Syndrome/genetics , 22q11 Deletion Syndrome/psychology , Animals , Blood-Brain Barrier/metabolism , Brain/metabolism , Disease Models, Animal , Endothelial Cells/metabolism , Female , Gene Expression Profiling/methods , HEK293 Cells , Humans , Male , Mice , Mice, Inbred C57BL , Schizophrenia/physiopathology , Tight Junctions
7.
Nurse Educ Pract ; 17: 182-7, 2016 Mar.
Article in English | MEDLINE | ID: mdl-26589096

ABSTRACT

Investigations into Medical Emergency Team (MET) calls and related clinical incident reviews at a large district teaching hospital provided evidence that over sedation can be a significant issue post opioid administration and that safe and effective pain management requires accurate opioid knowledge and patient assessment skills. The aim of the study was to develop education that was directed at identified knowledge deficits, and to evaluate the impact of this tailored education program on knowledge of safe prescribing and administration of opioids. Knowledge levels were explored using a structured questionnaire in a pre and post-test design. A convenience sample of 34 nurses and 5 junior medical officers across three surgical wards in a tertiary referral hospital had their knowledge assessed. Results showed significant improvement when repeat questionnaires were given two weeks post-delivery of education. Mean scores were 68% at baseline and 89% two weeks post completion of the education program. The greatest improvement in scores was recorded for drug knowledge including dose, half-life and administration. The findings from this study suggest that the opioid education program is effective in improving the knowledge of safe prescribing and administration of opioids, however further studies are required.


Subject(s)
Analgesics, Opioid/administration & dosage , Health Knowledge, Attitudes, Practice , Hospitalization , Quality Improvement , Analgesics, Opioid/therapeutic use , Drug Utilization , Humans , Medical Staff, Hospital , New South Wales , Nursing Staff, Hospital , Pain Management/methods , Practice Patterns, Physicians' , Risk Factors , Surveys and Questionnaires
8.
Adv Exp Med Biol ; 859: 127-45, 2015.
Article in English | MEDLINE | ID: mdl-26238051

ABSTRACT

Optical recording with fast voltage sensitive dyes makes it possible, in suitable preparations, to simultaneously monitor the action potentials of large numbers of individual neurons. Here we describe methods for doing this, including considerations of different dyes and imaging systems, methods for correlating the optical signals with their source neurons, procedures for getting good signals, and the use of Independent Component Analysis for spike-sorting raw optical data into single neuron traces. These combined tools represent a powerful approach for large-scale recording of neural networks with high temporal and spatial resolution.


Subject(s)
Action Potentials/physiology , Ganglia, Invertebrate/physiology , Nerve Net/physiology , Neurons/physiology , Synapses/physiology , Voltage-Sensitive Dye Imaging/methods , Animals , Fluorescent Dyes/chemistry , Ganglia, Invertebrate/ultrastructure , Image Processing, Computer-Assisted/methods , Leeches , Nerve Net/ultrastructure , Neurons/ultrastructure , Spatio-Temporal Analysis , Synapses/ultrastructure , Tritonia Sea Slug , Voltage-Sensitive Dye Imaging/instrumentation
9.
J Evol Biol ; 28(6): 1203-12, 2015 Jun.
Article in English | MEDLINE | ID: mdl-25847376

ABSTRACT

Most empirical attempts to explain the evolution of parental care have focused on its costs and benefits (i.e. fitness consequences). In contrast, few investigations have been made of the other necessary prerequisite for evolutionary change, inheritance. Here, we examine the fitness consequences and heritability (h(2)) of a post-weaning parental care behaviour (territory bequeathal) in a wild population of North American red squirrels. Each year, a subset (average across all years = 19%) of reproductive females bequeathed their territory to a dependent offspring. Bequeathing females experienced higher annual reproductive success and did not suffer a survival cost to themselves relative to those females retaining their territory. Bequeathing females thus realized higher relative annual fitness [ω = 1.18 ± 0.03 (SE)] than nonbequeathing females [ω = 0.96 ± 0.02 (SE)]. Additive genetic influences on bequeathal behaviour, however, were not significantly different from 0 (h(2) = 1.9 × 10(-3); 95% highest posterior density interval = 3.04 × 10(-8) to 0.37) and, in fact, bequeathal behaviour was not significantly repeatable (R = 2.0 × 10(-3); 95% HPD interval = 0-0.27). In contrast, directional environmental influences were apparent. Females were more likely to bequeath in years following low food abundance and when food availability in the upcoming autumn was high. Despite an evident fitness benefit, a lack of heritable genetic variance will constrain evolution of this trait.


Subject(s)
Genetic Fitness , Parenting , Sciuridae/genetics , Sciuridae/physiology , Weaning , Aging , Animals , Female , Territoriality
10.
Chem Sci ; 6(9): 5144-5151, 2015 Sep 01.
Article in English | MEDLINE | ID: mdl-29142733

ABSTRACT

Electrophilic borylation using BCl3 and benzothiadiazole to direct the C-H functionalisation of an adjacent aromatic unit produces fused boracyclic materials with minimally changed HOMO energy levels but significantly reduced LUMO energy levels. In situ alkylation and arylation at boron using Al(alkyl)3 or Zn(aryl)2 is facile and affords boracycles that possess excellent stability towards protic solvents, including water, and display large bathochromic shifts leading to far red/NIR emission in the solid state with quantum yields of up to 34%. Solution fabricated OLEDs with far red/NIR electroluminescence are reported with EQEs > 0.4%.

11.
J Evol Biol ; 27(11): 2308-21, 2014 Nov.
Article in English | MEDLINE | ID: mdl-25293495

ABSTRACT

Temporal variation in selection has long been proposed as a mechanism by which genetic variation could be maintained despite short-term strong directional selection and has been invoked to explain the maintenance of consistent individual differences in behaviour. We tested the hypothesis that ecological changes through time lead to fluctuating selection, which could promote the maintenance of variation in female behavioural traits in a wild population of North American red squirrels. As predicted, linear selection gradients on female aggression and activity significantly fluctuated across years depending on the level of competition among juveniles for vacant territories. This selection acted primarily through juvenile overwinter survival rather than maternal fecundity. Incorporating uncertainty in individual measures of behaviour reduced the magnitude of annual selection gradients and increased uncertainty in these estimates, but did not affect the overall pattern of temporal fluctuations in natural selection that coincided with the intensity of competition for vacant territories. These temporal fluctuations in selection might, therefore, promote the maintenance of heritable individual differences in behaviour in this wild red squirrel population.


Subject(s)
Behavior, Animal , Selection, Genetic , Aggression , Animals , Biological Evolution , Environment , Female , Fertility , Genetic Variation , Maternal Behavior , Sciuridae/genetics , Sciuridae/physiology
12.
J Evol Biol ; 26(4): 766-74, 2013 Apr.
Article in English | MEDLINE | ID: mdl-23437956

ABSTRACT

Heterogeneous forces of selection associated with fluctuating environments are recognized as important factors involved in the maintenance of inter-individual phenotypic variance within populations. Consistent behavioural differences over time and across situations (e.g. personality) are increasingly cited as examples of individual variation observed within populations. However, the suggestion that heterogeneous selective pressures target different animal personalities remains largely untested in the wild. In this 5-year study, we investigated the dynamics of viability selection on a personality trait, exploration, in a population of eastern chipmunks (Tamias striatus) experiencing substantial seasonal variations in weather conditions and food availability associated with masting trees. Contrary to our expectations, we found no evidence of fluctuating selection on exploration. Instead, we found strong disruptive viability selection on adult exploration behaviour, independent of seasonal variations. Individuals with either low or high exploration scores were almost twice as likely to survive over a 6-month period compared with individuals with intermediate scores. We found no evidence of viability selection on juvenile exploration. Our results highlight that disruptive selection might play an important role in the maintenance of phenotypic variance of wild populations through its effect on different personality types across temporally varying environmental conditions.


Subject(s)
Behavior, Animal/physiology , Exploratory Behavior/physiology , Sciuridae/physiology , Selection, Genetic , Animals , Female , Male , Models, Biological , Personality , Phenotype , Seasons , Survival Analysis , Time Factors
13.
J Evol Biol ; 25(4): 614-24, 2012 Apr.
Article in English | MEDLINE | ID: mdl-22268892

ABSTRACT

Consistent individual differences in behaviour, and behavioural correlations within and across contexts, are referred to as animal personalities. These patterns of variation have been identified in many animal taxa and are likely to have important ecological and evolutionary consequences. Despite their importance, genetic and environmental sources of variation in personalities have rarely been characterized in wild populations. We used a Bayesian animal model approach to estimate genetic parameters for aggression, activity and docility in North American red squirrels (Tamiasciurus hudsonicus). We found support for low heritabilities (0.08-0.12), and cohort effects (0.07-0.09), as well as low to moderate maternal effects (0.07-0.15) and permanent environmental effects (0.08-0.16). Finally, we found evidence of a substantial positive genetic correlation (0.68) and maternal effects correlation (0.58) between activity and aggression providing evidence of genetically based behavioural correlations in red squirrels. These results provide evidence for the presence of heritable variation in red squirrel behaviour, but also emphasize the role of other sources of variation, including maternal effects, in shaping patterns of variation and covariation in behavioural traits.


Subject(s)
Behavior, Animal , Sciuridae/genetics , Animals , Female , Gene-Environment Interaction , Genetic Variation , Male , Phenotype , Sciuridae/physiology
14.
J Evol Biol ; 24(8): 1685-94, 2011 Aug.
Article in English | MEDLINE | ID: mdl-21585586

ABSTRACT

Mate selection for inbreeding avoidance is documented in several taxa. In mammals, most conclusive evidence comes from captive experiments that control for the availability of mates and for the level of genetic relatedness between mating partners. However, the importance of mate selection for inbreeding avoidance as a determinant of siring success in the wild has rarely been addressed. We followed the reproduction of a wild population of eastern chipmunks (Tamias striatus) during five breeding seasons between 2006 and 2009. Using molecular tools and parentage assignment methods, we found that multiple paternity (among polytocous litters) varied from 25% in an early-spring breeding season when less than a quarter of females in the population were reproductively active to 100% across three summer breeding seasons and one spring breeding season when more than 85% of females were reproductively active. Genetically related parents were common in this population and produced less heterozygous offspring. Furthermore, litters with multiple sires showed a higher average relatedness among partners than litters with only a single sire. In multiply sired litters, however, males that were more closely related to their partners sired fewer offspring. Our results corroborate findings from captive experiments and suggest that selection for inbreeding avoidance can be an important determinant of reproductive success in wild mammals.


Subject(s)
Inbreeding , Mating Preference, Animal , Sciuridae/physiology , Animals , Female , Genotype , Male , Microsatellite Repeats
15.
Bioorg Med Chem Lett ; 20(9): 2832-6, 2010 May 01.
Article in English | MEDLINE | ID: mdl-20356739

ABSTRACT

The purpose of the work was to identify novel inhibitors of the enzyme NQO2. Using computational molecular modelling, a QSAR (R(2)=0.88) was established, relating inhibitory potency with calculated binding affinity. From this, the imidazoacridin-6-one, NSC660841, was identified as the most potent inhibitor of NQO2 yet reported (IC(50)=6 nM).


Subject(s)
Acridines/chemistry , Acridones/chemistry , Enzyme Inhibitors/chemistry , Imidazoles/chemistry , Quinone Reductases/antagonists & inhibitors , Acridines/pharmacology , Acridones/pharmacology , Binding Sites , Catalytic Domain , Computer Simulation , Databases, Factual , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Humans , Imidazoles/pharmacology , Quantitative Structure-Activity Relationship , Quinone Reductases/metabolism , Thermodynamics
16.
Adv Exp Med Biol ; 664: 437-46, 2010.
Article in English | MEDLINE | ID: mdl-20238045

ABSTRACT

Age-related macular degeneration (AMD) is the most common form of visual impairment, in people over 65, in the Western world. AMD is a multifactorial disease with genetic and environmental factors influencing disease progression. Cigarette smoking is the most significant environmental influence with an estimated increase in risk of 2- to 4-fold. Smoke-induced damage in AMD is mediated through direct oxidation, depletion of antioxidant protection, immune system activation and atherosclerotic vascular changes. Moreover, cigarette smoke induces angiogenesis promoting choroidal neovascularisation and progression to neovascular AMD. Further investigation into the effects of cigarette smoke through in vitro and in vivo experimentation will provide a greater insight into the pathogenesis of age-related macular degeneration.


Subject(s)
Macular Degeneration/complications , Macular Degeneration/physiopathology , Smoking/physiopathology , Antioxidants/metabolism , Humans , Inflammation/pathology , Oxidative Stress , Risk Factors
17.
Parasite Immunol ; 31(12): 750-65, 2009 Dec.
Article in English | MEDLINE | ID: mdl-19891613

ABSTRACT

The development of a protective immune response in sheep towards the presence of the larval stage of Lucilia cuprina has not been reported in the field. Upon investigation of the effects of larval excretory/secretory material on ovine T lymphocyte proliferation, we isolated a 56 kDa protein capable of inhibiting lymphocyte proliferation by at least 70%, compared with that in the presence of mitogen alone. This protein inhibited proliferation induced through cross-linking of the T-cell receptor as well as proliferation induced pharmacologically through the stimulation of the protein kinase C (PKC) pathway. The protein, named blowfly larval immunosuppressive protein (BLIP), was shown to bind directly to lymphocytes. Further investigation revealed that the BLIP prevented a proportion of lymphocytes from entering the first division following stimulation, by affecting the early events in lymphocyte activation. Subsequently, the BLIP reduced CD25 expression on T lymphocytes, reduced IL-2 mRNA expression, in addition to IFN-gamma, IL-4, IL-10 and IL-13 mRNA expression. Conversely, TNF-alpha and TGF-beta gene expression was up-regulated in response to the BLIP. These effects suggest suboptimal activation of T lymphocytes in the presence of the BLIP, and we propose that the BLIP presents an effective immune evasion tactic for the larvae of L. cuprina.


Subject(s)
Diptera/immunology , Insect Proteins/immunology , Myiasis/veterinary , Sheep Diseases/immunology , Sheep/parasitology , T-Lymphocytes/immunology , Adaptive Immunity , Amino Acid Sequence , Animals , Cell Proliferation , Cytokines/biosynthesis , Cytokines/genetics , Gene Expression Regulation , Insect Proteins/chemistry , Insect Proteins/genetics , Interleukin-2 Receptor alpha Subunit/genetics , Interleukin-2 Receptor alpha Subunit/metabolism , Larva/immunology , Lymphocyte Activation/genetics , Molecular Sequence Data , Myiasis/immunology , Myiasis/parasitology , Protein Binding , Sequence Alignment , Sheep/immunology , Sheep Diseases/parasitology
19.
Exp Cell Res ; 314(3): 498-508, 2008 Feb 01.
Article in English | MEDLINE | ID: mdl-18155697

ABSTRACT

Integrins are transmembrane adhesion proteins that convey critical topobiological information and exert crucial signalling functions. In skin and hair follicle biology, beta1 integrins and their ligands are of particular interest. It is not yet known whether beta1 integrins play any role in the regulation of human hair growth and the expression pattern of beta1 integrin in the human pilosebaceous unit remains ill-defined. Here, we show that pilosebaceous immunoreactivity for beta1 integrin is most prominent in the outermost layer of the outer root sheath and the surrounding connective tissue sheath of human scalp hair follicles in situ and in vitro. Sites of beta1 integrin immunoreactivity co-express fibronectin and tenascin-C. Contrary to previous reports, beta1 integrin immunoreactivity in situ was not significantly upregulated in the human bulge region. Functionally, two beta1 integrin-activating antibodies (12G10, TS2/16) and ligand-mimicking RGD peptides promoted the growth of microdissected, organ-cultured human scalp hair follicles in vitro and inhibited spontaneous hair follicle regression. This supports the concept that beta1 integrin-mediated signalling is also important in human hair growth control. The physiologically relevant organ culture assay employed here is a potential research tool for exploring whether targeted stimulation of beta1 integrin-mediated signalling is a suitable candidate for human hair loss management.


Subject(s)
Hair Follicle/metabolism , Integrin beta1/metabolism , Signal Transduction/physiology , Antibodies/pharmacology , Biological Assay/methods , Cells, Cultured , Connective Tissue/metabolism , Connective Tissue/ultrastructure , Epithelial Cells/drug effects , Epithelial Cells/metabolism , Epithelial Cells/ultrastructure , Female , Fibronectins/metabolism , Hair/drug effects , Hair/growth & development , Hair/metabolism , Hair Follicle/drug effects , Hair Follicle/ultrastructure , Humans , Immunohistochemistry , Integrin beta1/drug effects , Integrin beta1/genetics , Ligands , Organ Culture Techniques , Peptides/pharmacology , Tenascin/metabolism
20.
Ecology ; 89(12): 3306-16, 2008 Dec.
Article in English | MEDLINE | ID: mdl-19137938

ABSTRACT

Torpor is a reversible reduction in endotherm body temperature and metabolic rate. Because torpid endotherms can attain lower body temperatures in colder environments, minimum torpor metabolism generally increases with rising air temperature whereas euthermic metabolism generally declines with rising air temperature. As a result, the fundamental metabolic niche of endotherms that express torpor should be driven by climate and should be broadest in colder environments. On the other hand, if torpor serves primarily as an energy conservation strategy and its expression is influenced by energy availability, then the realized metabolic niche should be defined by resources. To evaluate the influence of resource and climate on torpor use and metabolism of hibernating mammals, we monitored the torpor expression of free-ranging eastern chipmunks (Tamias striatus) over two winters of varying resource abundance. In the low-food year, soil temperature constrained maximum torpor expression but was too invariant across small spatial scales to explain individual variation in torpor expression. In the high-food year, torpor was drastically reduced, and local density of seed-producing trees predicted fine-scale spatial variation in torpor expression. Thus, the fundamental metabolic niche of hibernating chipmunks in cold environments is broad and constrained by climate, whereas the realized metabolic niche is highly variable among individuals and years and is determined primarily by local resource abundance.


Subject(s)
Climate , Energy Metabolism/physiology , Food Supply , Hibernation/physiology , Sciuridae/physiology , Analysis of Variance , Animals , Body Temperature/physiology , Female , Food Deprivation/physiology , Male , Sciuridae/metabolism , Telemetry
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