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Environmental Stressors (environmental + stressor)
Selected AbstractsTime-distributed effect of exposure and infectious outbreaksENVIRONMETRICS, Issue 3 2009Elena N. Naumova Abstract Extreme weather affects the timing and intensity of infectious outbreaks, the resurgence and redistribution of infections, and it causes disturbances in human-environment interactions. Environmental stressors with high thermoregulatory demands require susceptible populations to undergo physiological adaptive processes potentially compromising immune function and increasing susceptibility to infection. In assessing associations between environmental exposures and infectious diseases, failure to account for a latent period between time of exposure and time of disease manifestation may lead to severe underestimation of the effects. In a population, health effects of an episode of exposure are distributed over a range of time lags. To consider such time-distributed lags is a challenging task given that the length of a latent period varies from hours to months and depends on the type of pathogen, individual susceptibility to the pathogen, dose of exposure, route of transmission, and many other factors. The two main objectives of this communication are to introduce an approach to modeling time-distributed effect of exposures to infection cases and to demonstrate this approach in an analysis of the association between high ambient temperature and daily incidence of enterically transmitted infections. The study is supplemented with extensive simulations to examine model sensitivity to response magnitude, exposure frequency, and extent of latent period. Copyright © 2008 John Wiley & Sons, Ltd. [source] Chemical stress induces the unfolded protein response in olfactory sensory neuronsTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 10 2010Neeraja Sammeta Abstract More than any other neuron, olfactory sensory neurons are exposed to environmental insults. Surprisingly, their only documented response to damaging stress is apoptosis and subsequent replacement by new neurons. However, they expressed unfolded protein response genes, a transcriptionally regulated defense mechanism activated by many types of insults. The unfolded protein response transcripts Xbp1, spliced Xbp1, Chop (Ddit3), and BiP (Hspa5) were decreased when external access of stressors was reduced by blocking a nostril (naris occlusion). These transcripts and Nrf2 (Nfe2l2) were increased by systemic application of tunicamycin or the selective olfactotoxic chemical methimazole. Methimazole's effects overcame naris occlusion, and the unfolded protein response was independent of odor-evoked neuronal activity. Chemical stress is therefore a major and chronic activator of the unfolded protein response in olfactory sensory neurons. Stress-dependent repression of the antiapoptotic gene Bcl2 was absent, however, suggesting a mechanism for disconnecting the UPR from apoptosis and tolerating a chronic unfolded protein response. Environmental stressors also affect both the sustentacular cells that support the neurons and the respiratory epithelia, because naris occlusion decreased expression of the xenobiotic chemical transformation enzyme Cyp2a5 in sustentacular cells, and both naris occlusion and methimazole altered the abundance of the antibacterial lectin Reg3g in respiratory epithelia. J. Comp. Neurol. 518:1825,1836, 2010. © 2009 Wiley-Liss, Inc. [source] Measuring the amount of statistical information in the EPT indexENVIRONMETRICS, Issue 1 2005Patty L. Kitchin Abstract Biological monitoring is the process of measuring the effect of environmental stress on the environment. Aquatic macroinvertebrates are widely used in the monitoring of freshwater lotic systems. The macroinvertebrate fauna of a reference stream is commonly compared to the fauna of an impacted stream that is affected by an environmental stressor. The smaller the similarity between these two streams, the greater the effect of pollution or stress on the impacted stream. Many richness measures, or statistics, exist for measuring similarity. These statistics can be computed using different levels of taxonomic resolution (species, genus and family). Many aquatic biologists believe that species-level identifications, which require exorbitant time and expertise, are needed for correct data interpretations. The actual amount of information provided by these statistics at different taxonomic levels has never been measured. This article evaluates the amount of statistical information provided by the EPT index as compared to a sufficient statistic at the various levels of taxonomic resolution. Copyright © 2004 John Wiley & Sons, Ltd. [source] Altered behavioural adaptation in mice with neural corticotrophin-releasing factor overexpressionGENES, BRAIN AND BEHAVIOR, Issue 7 2007M. Kasahara Overproduction of corticotrophin-releasing factor (CRF), the major mediator of the stress response, has been linked to anxiety, depression and addiction. CRF excess results in increased arousal, anxiety and altered cognition in rodents. The ability to adapt to a potentially threatening stimulus is crucial for survival, and impaired adaptation may underlie stress-related psychiatric disorders. Therefore, we examined the effects of chronic transgenic neural CRF overproduction on behavioural adaptation to repeated exposure to a non-home cage environment. We report that CRF transgenic mice show impaired adaptation in locomotor response to the novel open field. In contrast to wild-type (WT) mice, anxiety-related behaviour of CRF transgenic mice does not change during repeated exposure to the same environment over the period of 7 days or at retest 1 week later. We found that locomotor response to novelty correlates significantly with total locomotor activity and activity in the centre at the last day of testing and at retest in WT but not in CRF transgenic mice. Mice were divided into low responders and high responders on the basis of their initial locomotor response to novelty. We found that differences in habituation and re-exposure response are related to individual differences in locomotor response to novelty. In summary, these results show that CRF transgenic mice are fundamentally different from WT in their ability to adapt to an environmental stressor. This may be related to individual differences in stress reactivity. These findings have implications for our understanding of the role of CRF overproduction in behavioural maladaptation and stress-related psychiatric disorders. [source] Variation in Pesticide Tolerance of Tadpoles among and within Species of Ranidae and Patterns of Amphibian DeclineCONSERVATION BIOLOGY, Issue 5 2000Christine M. Bridges Because variability exists among organisms in their sensitivity to environmental stressors, it is important to determine the degree of this variation when undertaking conservation efforts. We conducted both lethal (time-to-death) and sublethal (activity change) assays to determine the degree of variation in the sensitivity of tadpoles to a pesticide, carbaryl, at three hierarchical levels: among ranid species, among several populations of a single ranid species ( Rana sphenocephala), and within populations of R. sphenocephala. We observed significant variation in time to death among the nine ranid species and among the 10 R. sphenocephala populations we tested. Four out of eight R. sphenocephala populations exhibited significantly different times to death among families. The magnitude of the activity change in response to exposure to sublethal carbaryl levels was significantly different among species and within R. sphenocephala populations. Chemical contamination, at lethal or sublethal levels, can alter natural regulatory processes such as juvenile recruitment in amphibian populations and should be considered a contributing cause of declines in amphibian populations. Resumen: Existe una variación significativa entre y dentro de especies de anfibios con respecto a los reportes de disminuciones poblacionales; las especies en disminución son frecuentemente encontradas en ambientes que son fisiográficamente similares a ambientes donde las mismas especies están prosperando. Debido a que la variabilidad existe entre organismos en lo referente a su sensibilidad a estresores ambientales, es importante determinar el grado de esta variación cuando se lleven a cabo esfuerzos de conservación. Nosotros llevamos a cabo ensayos tanto letales (tiempo de muerte) como subletales (cambios de actividad) para determinar el grado de variación en la sensibilidad de renacuajos a un pesticida, carbaryl, en tres niveles jerárquicos: entre especies de ránidos, entre diversas poblaciones de una sola especie de ránido ( Rana sphenocephala) y dentro de poblaciones de R. sphenocephala. Observamos diferencias significativas en tiempo de muerte entre las nueve especies de ránidos y entre las 10 poblaciones de R. sphenocephala evaluadas. Cuatro de ocho poblaciones de R. sphenocephala exhibieron tiempos de muerte significativamente diferentes entre familias. La magnitud del cambio de actividad al ser expuestas a niveles subletales de carbaryl fue significativamente diferente entre especies y dentro de poblaciones de R. sphenocephala. La contaminación química, a niveles letales y subletales, puede alterar los procesos reguladores naturales (por ejemplo el reclutamiento de juveniles) en poblaciones de anfibios y debería ser considerado como una causa que contribuye a la disminución de poblaciones de anfibios. [source] Testing mechanisms of action for intensive case managementADDICTION, Issue 3 2008Jon Morgenstern ABSTRACT Aim This study identified factors that predict, mediate or moderate the effects of intensive case management (ICM) on longer-term drug abstinence outcomes in women on welfare. Design In a parent study women were assigned randomly to usual care (UC) or intensive case manangement (ICM). Treatment was provided for 12 weeks and follow-up continued for 15 months after study intake. A set of hypothesized mediators was assessed at month 3 and a rigorous four-step mediational model was tested using outcomes in months 4,15. Participants Participants were 302 drug-dependent women applying and eligible for federal welfare and not currently in drug abuse treatment. Interventions ICM provided intensive treatment engagement including voucher incentives for treatment attendance and case management services; UC provided primarily referral to community treatment programs. Measurement Substance use outcomes were assessed using the time-line follow-back interview and confirmed using biological and collateral measures. Findings Participants in ICM had more case manager contacts, better treatment engagement and more self-help attendance than did those in UC. Each of these variables predicted, and was shown to be a mediator of outcome, but case management contact was an especially robust mediator. Further, ICM effects were strongest for those who attended treatment least. Contrary to prediction, greater psychopathology and environmental stressors did not predict worse outcomes. Conclusions Findings suggest that case management is an active intervention that may both facilitate and substitute for formal drug abuse treatment. [source] Aqueous exposure to 4-nonylphenol and 17,-estradiol increases stress sensitivity and disrupts ion regulatory ability of juvenile Atlantic salmonENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2007Darren T. Lerner Abstract Population declines of wild Atlantic salmon have been attributed to an array of anthropogenic disturbances, including dams, commercial and recreational fishing, habitat loss, and pollution. Environmental contaminants in particular, can act as environmental stressors on fish, typically causing disruption of ion homeostasis due to their close association with the aquatic environment. To examine the effects of the xenoestrogen 4-nonylphenol (NP) or 17,-estradiol (E2) on stress sensitivity and ion regulation, we exposed juvenile Atlantic salmon continuously for 21 d to either 10 or 100 ,g/L NP (NP-L or NP-H), 2 ,g/L E2 (positive control), or vehicle control during the parr-smolt transformation in April. After treatment, fish were sampled in freshwater (FW), transferred to 30, seawater (SW) for 24 h, or subjected to a handling stress. Estradiol and NP-H increased plasma vitellogenin in males and females, and E2 increased gonadosomatic index only in males. In FW, E2 reduced sodium potassium,activated adenosine triphosphatase activity as well as plasma levels of growth hormone, insulin-like growth factor I, and triiodothyronine. Both E2 and NP-H reduced plasma sodium in FW and increased plasma chloride in SW. Plasma Cortisol levels pre- and poststressor were significantly elevated by all treatments relative to controls, but only E2 increased plasma glucose before and after the stressor. These results indicate that exposure of anadromous salmonids to environmental estrogens heightens sensitivity to external stressors, impairs ion regulation in both FW and SW, and disrupts endocrine pathways critical for smolt development. [source] A Geographic Information Systems,based, weights-of-evidence approach for diagnosing aquatic ecosystem impairmentENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2006Katherine E. Kapo Abstract A Geographic Information Systems,based, watershed-level assessment using Bayesian weights of evidence (WOE) and weighted logistic regression (WLR) provides a method to determine and compare potential environmental stressors in lotic ecosystems and to create predictive models of general or species-specific biological impairment across numerous spatial scales based on limited existing sample data. The WOE/WLR technique used in the present study is a data-driven, probabilistic approach conceptualized in epidemiological research and both developed for and currently used in minerals exploration. Extrapolation of this methodology to a case-study watershed assessment of the Great and Little Miami watersheds (OH, USA) using archival data yielded baseline results consistent with previous assessments. The method additionally produced a quantitative determination of physical and chemical watershed stressor associations with biological impairment and a predicted comparative probability (i.e., favorability) of biological impairment at a spatial resolution of 0.5 km2 over the watershed study region. Habitat stressors showed the greatest spatial association with biological impairment in low-order streams (on average, 56% of total spatial association), whereas water chemistry, particularly that of wastewater effluent, was associated most strongly with biological impairment in high-order reaches (on average, 79% of total spatial association, 28% of which was attributed to effluent). Significant potential stressors varied by land-use and stream order as well as by species. This WOE/WLR method provides a highly useful "tier 1" watershed risk assessment product through the integration of various existing data sources, and it produces a clear visual communication of areas favorable for biological impairment and a quantitative ranking of candidate stressors and associated uncertainty. [source] GENETIC STUDY: Tryptophan hydroxylase 2 gene and alcohol use among college studentsADDICTION BIOLOGY, Issue 3-4 2008Paul Gacek ABSTRACT Genes that regulate serotonin activity are regarded as promising predictors of heavy alcohol use. Tryptophan hydroxylase (TPH2) plays an important role in serotonergic neurotransmission by serving as the rate-limiting enzyme for serotonin biosynthesis in the midbrain and serotonergic neurons. Despite the link between TPH2 and serotonergic function, TPH2's role in the pathogenesis of alcohol-use disorders remains unclear. The goal of this study was to examine whether a variation in the TPH2 gene is associated with risky alcohol consumption. Specifically, this study examined whether the TPH2 G-703T polymorphism predicted alcohol consumption among college students. In two successive years, 351 undergraduates were asked to record their alcohol use each day for 30 days using an Internet-based electronic diary. Participants' DNA was collected and polymerase chain reaction genotyping was performed. Results show that alcohol consumption was not associated with the TPH2 G-703T polymorphism alone, or the interaction of TPH2 with two other candidate polymorphisms (TPH1 C218A and the SLC6A4 tri-allelic 5-HTTLPR), or negative life events. In conclusion, this study supports recent null findings relating TPH2 to drinking outcomes. It also extends these findings by showing null interactions with the TPH1 C218A polymorphism, the SLC6A4 tri-allelic 5-HTTLPR polymorphism and environmental stressors in predicting sub-clinical alcohol use among Caucasian American young adults. [source] Consumer body composition and community structure in a stream is altered by pHFRESHWATER BIOLOGY, Issue 3 2010A. LARRAÑAGA Summary 1.,Low pH inhibits microbial conditioning of leaf-litter, which forms the principal energy input to many headwater streams. This reduces food quality and availability for the shredder assemblage, thereby creating a potential bottleneck in the flux of energy and biomass through acidified food webs. 2.,We explored the consequences of acidity on the well-characterised community of Broadstone Stream in southeast England, by quantifying the physiological condition (protein and lipid content) of three dominant shredder species (Leuctra nigra, L. hippopus and Nemurella pictetii) and relating this to changes in the numerical abundance and biomass of invertebrates across a longitudinal pH gradient (5.3,6.5). 3.,Total taxon richness increased with pH, as did shredder diversity. The acid-tolerant stonefly, L. nigra, exhibited a positive correlation between pH and protein content, but its abundance was suppressed in the less acid reaches. These results suggest that the impacts of environmental stressors might be manifested differently at the population (i.e. numerical and biomass abundance) versus the physiological (i.e. protein content of individuals) levels of organisation. Body composition of L. hippopus and N. pictetii did not exhibit any significant relationship with stream pH in the field. 4.,The survey data were corroborated with a laboratory rearing experiment using N. pictetii, in which survival rate, growth rate, and protein and lipid content of individuals were measured in stream water of differing pH and acid versus circumneutral microbial conditioning regimes. Acid-conditioned leaves were associated with increased mortality and reduced protein content in consumers' tissues, with acid water also having the latter effect. 5.,Our results suggest that biochemical constraints within key taxa might create energy flux bottlenecks in detrital-based food webs, and that this could ultimately determine the productivity of the entire system. Hence assays of the body composition of macroinvertebrates could be an effective new tool that complements population level studies of the impacts of stressors in fresh waters. [source] Ultrastructural and histochemical study on gills and skin of the Senegal sole, Solea senegalensisJOURNAL OF APPLIED ICHTHYOLOGY, Issue 6 2004J. M. Arellano Summary This study was undertaken to identify the normal ultrastructural features of gills and skin of the Senegal sole, Solea senegalensis, for a comparative measure to morphological alterations caused by environmental stressors such as reduced water quality and diseases. In the Senegal sole skin, four morphologically distinct layers were identified: cuticle, epidermis, dermis and hypodermis. The epidermis was composed of stratified epithelium containing three cellular layers: the outermost or mucosa layer, the middle or fusiform layer and the stratum germinativum or the basal layer. In the mucosa, two mucous cell types were differentiated: type A cells containing several round vesicles of different electron density and type B cells containing mucosomes of uniform electron density. Senegal sole have five pairs of gill arches, each containing two rows of well-developed and compactly organized primary filaments and secondary lamellae. Fingerprint-like microridges were observed on the surface of epithelial cells. The branchial lamellae epithelium consisted of different cell types: pavement, mucous and chloride. Between the chloride cells and the larger pavement cells, accessory cells were observed. Complexes of tight junctions and desmosomes were frequently observed between adjacent chloride and epithelial cells. Neutral mucosubstances and/or glycoconjugates were observed in the epidermis, dermis and hypodermis of S. senegalensis skin. Proteins rich in different amino acids, such as arginine and cysteine, reacted negatively or weakly positive in the epidermis, dermis and hypodermis. In gills, some mucous cells responded weakly positive to periodic acid-Schiff (PAS) reaction but were strongly stained with Alcian Blue at pH 0.5, 1 and 2.5. When Alcian Blue pH 2.5,PAS reaction was performed, most mucous cells were stained blue (carboxylated mucins) and some mucocytes stained purple, indicating a combination of neutral and acid mucins. Proteins rich in cysteine-bound sulphydryl (-SH-) and cystine disulphide (-S-S-) groups were strongly detected in branchial and epidermal mucous cells, whereas lysine, tyrosine and arginine containing proteins showed very weak staining in both epidermal and branchial mucous cells. Protein reactions were strongly positive in the pillar cells, except for those rich in tryptophan, whereas the branchial cartilaginous tissue did not show an important reaction. The performed lipid reactions were negative in goblet and chloride cells. It is concluded from this study that ultrastructural and cytohistochemical features of the Senegal sole skin and gills may serve as control structures in both natural and aquaculture systems to monitor or detect environmental stress responses at the histological level. [source] Global Change Effects on Plant Chemical Defenses against Insect HerbivoresJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 11 2008M. Gabriela Bidart-Bouzat Abstract This review focuses on individual effects of major global change factors, such as elevated CO2, O3, UV light and temperature, on plant secondary chemistry. These secondary metabolites are well-known for their role in plant defense against insect herbivory. Global change effects on secondary chemicals appear to be plant species-specific and dependent on the chemical type. Even though plant chemical responses induced by these factors are highly variable, there seems to be some specificity in the response to different environmental stressors. For example, even though the production of phenolic compounds is enhanced by both elevated CO2 and UV light levels, the latter appears to primarily increase the concentrations of flavonoids. Likewise, specific phenolic metabolites seem to be induced by O3 but not by other factors, and an increase in volatile organic compounds has been particularly detected under elevated temperature. More information is needed regarding how global change factors influence inducibility of plant chemical defenses as well as how their indirect and direct effects impact insect performance and behavior, herbivory rates and pathogen attack. This knowledge is crucial to better understand how plants and their associated natural enemies will be affected in future changing environments. [source] Hydrogen Peroxide in Plants: a Versatile Molecule of the Reactive Oxygen Species NetworkJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 1 2008Li-Juan Quan Abstract Plants often face the challenge of severe environmental conditions, which include various biotic and abiotic stresses that exert adverse effects on plant growth and development. During evolution, plants have evolved complex regulatory mechanisms to adapt to various environmental stressors. One of the consequences of stress is an increase in the cellular concentration of reactive oxygen species (ROS), which are subsequently converted to hydrogen peroxide (H2O2). Even under normal conditions, higher plants produce ROS during metabolic processes. Excess concentrations of ROS result in oxidative damage to or the apoptotic death of cells. Development of an antioxidant defense system in plants protects them against oxidative stress damage. These ROS and, more particularly, H2O2, play versatile roles in normal plant physiological processes and in resistance to stresses. Recently, H2O2 has been regarded as a signaling molecule and regulator of the expression of some genes in cells. This review describes various aspects of H2O2 function, generation and scavenging, gene regulation and cross-links with other physiological molecules during plant growth, development and resistance responses. [source] Feeding Dietary Mannan Oligosaccharides to Juvenile Nile Tilapia, Oreochromis niloticus, Has No Effect on Hematological Parameters and Showed Decreased Feed ConsumptionJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 6 2008Ricardo Yuji Sado Impaired immune system by environmental stressors can lead fishes to be more susceptible to diseases that limit the economic development of aquaculture systems. This study was set out to determine the effect of six levels of mannan oligosaccharides (MOS; ActiveMOS®; Biorigin, Lençois Paulista, São Paulo, Brazil) on the performance index and hematology of Nile tilapia, Oreochromis niloticus juveniles. Fish (13.62 g) were randomly distributed into 18 plastic aquaria (300 L; 20 fishes per aquarium) and fed during 45 d with a commercial diet supplemented with 0, 0.2, 0.4, 0.6, 0.8, and 1% dietary MOS, in a totally randomized design trial (n = 3); biometrical and hematological data were collected and analyzed. There were no significant differences in hematological parameters between fish fed control and MOS supplementation diets, and daily feed consumption (FC) decreased (P < 0.05) with increasing levels of dietary MOS. Dietary MOS did not increase leukocyte count and presented negative effects on FC of Nile tilapia. At 0.4% MOS supplementation, the individual weight gain was higher in absolute values but not different (P > 0.05) compared to control diet. [source] Structural and bioinformatic analysis of the Roman snail Cd-Metallothionein gene uncovers molecular adaptation towards plasticity in coping with multifarious environmental stressMOLECULAR ECOLOGY, Issue 11 2009MARGIT EGG Abstract Metallothioneins (MTs) are a family of multifunctional proteins involved, among others, in stress response. The Cadmium (Cd)-MT gene of the Roman snail (Helix pomatia), for example, encodes for a protein induced upon cadmium exposure. While our previous studies have demonstrated that the expressed Cd-MT isoform of Roman snails assists detoxification of cadmium, the present work focuses on the potential plasticity of this gene in response to a variety of environmental stressors playing a crucial role in the specific ecological niche of H. pomatia. Our hypothesis is based on a bioinformatic approach involving gene sequencing, structural and in silico analysis of transcription factor binding sites (TFBs), and a comparison of these features with other MT genes. Our results show that the Roman snail's Cd-MT gene not only is the largest known MT gene, but also contains , apart from the regulatory promoter region , several intronic repeat cassettes of putative TFBs suggested to be involved in environmental stress response, immune competence, and regulation of gene expression. Moreover, intronic scaffold/matrix attachment regions (S/MARs) and stress-induced duplex destabilization sites confer a high potential for epigenetic gene regulation. This suggested regulatory plasticity is also supported by physiological data showing that Cd-MT in Roman snails can be induced differentially not only after cadmium exposure, but also in response to nonmetallic environmental stressors. It is concluded that structural analysis combined with bioinformatic screening may constitute valuable tools for predicting the potential for plasticity and niche-specific adaptation of stress-responsive genes in populations living under rapidly changing environmental conditions. [source] Is boron nutritionally relevant?NUTRITION REVIEWS, Issue 4 2008Forrest H Nielsen Evidence from numerous laboratories using a variety of experimental models, including humans, shows that boron is a bioactive beneficial element. Much evidence has come from studies that did not require nutritional or environmental stressors or fastidious methods in diet preparation or environmental control. The evidence includes deprivation studies showing that boron is necessary for some higher animals to complete the life cycle, and that realistic low boron intakes result in impaired bone health, brain function, and immune response. Thus, low boron intake is a relevant nutritional concern, which diets rich in fruits, vegetables, nuts, and pulses can prevent. [source] Is there an elephant in the room?AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2007Addressing rival approaches to the interpretation of growth perturbations, small size Two interpretations of growth perturbation and small size are commonly applied in human biology: an adaptationist approach in which small size is considered to be an a relatively beneficial adjustment to environmental stressors, and a biomedical approach in which small size is considered nonadaptive, a sign of dysfunction or pathology. These two interpretations conflict, but are used without acknowledging or addressing the conflict. This article reviews the strengths and weaknesses of the two. This exercise does not prove the indisputable superiority of either approach. Considerations of epistemology show that biologists will never be faced with a decisive test of either, much as they might like such clear cut evidence. Nevertheless, it is possible that a gradual decrease in the productivity of one approach will become a sufficient reason to abandon it. Alternatively, if specific areas of application can be distinguished, each approach might continue to be productive in its own domain. Am. J. Hum. Biol., 2007. © 2007 Wiley-Liss, Inc. [source] Adaptive dimensions of health research among indigenous Siberians,AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 2 2007J. Josh Snodgrass Present evidence suggests that modern humans were the first hominid species to successfully colonize high-latitude environments (,55°N). Given evidence for a recent (<200,000 years) lower latitude naissance of modern humans, the global dispersal and successful settlement of arctic and subarctic regions represent an unprecedented adaptive shift. This adaptive shift, which included cultural, behavioral, and biological dimensions, allowed human populations to cope with the myriad environmental stressors encountered in circumpolar regions. Although unique morphological and physiological adaptations among contemporary northern residents have been recognized for decades, human biologists are only now beginning to consider whether biological adaptations to regional environmental conditions influence health changes associated with economic modernization and lifestyle change. Recent studies have documented basal metabolic rates (BMRs) among indigenous Siberian populations that are systematically elevated compared to lower latitude groups; this metabolic elevation apparently is a physiological adaptation to cold stress experienced in the circumpolar environment. Important health implications of metabolic adaptation are suggested by research with the Yakut (Sakha), Evenki, and Buriat of Siberia. BMR is significantly positively correlated with blood pressure, independently of body size, body composition, and various potentially confounding variables (e.g., age and smoking). Further, this research has documented a significant negative association between BMR and LDL cholesterol, which remains after controlling for potential confounders; this suggests that high metabolic turnover among indigenous Siberians has a protective effect with regard to plasma lipid levels. These results underscore the importance of incorporating an evolutionary approach into health research among northern populations. Am. J. Hum. Biol. 19:165,180, 2007. © 2007 Wiley-Liss, Inc. [source] Ecological stress and linear enamel hypoplasia in CebusAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2010Madeleine B. Chollet Abstract Although it is assumed that monkeys in some environments experience more nutritional or physiological stress than others, little research has been conducted on this topic. This study examines the relationship between linear enamel hypoplasia (LEH) frequency, a physiological indicator of stress, and environmental stressors. To test this relationship, LEH frequencies were calculated for 144 Cebus from 54 locations in Brazil. Habitat, temperature range, and annual rainfall were compared between individuals with and without LEH. The LEH frequency for Cebus from semideciduous forests was significantly higher than that for monkeys from coastal areas, the rainforest, and the savanna (,2 = 9.97, df = 1; P = 0.0016). A significantly higher LEH frequency was also found for monkeys living in environments with the mean annual temperature between 15 and 18°C than for those in environments greater than 18°C (,2 = 7.74, df = 1, P = 0.0054). However, no significant difference was found between LEH frequency and annual rainfall (t = 1.22, P = 0.23) or the average difference in rainfall between the driest and wettest months (t = 0.77, P = 0.44). These results indicate that levels of physiological stress can differ among environments and that habitat and temperature, but not precipitation, may be driving the difference in stress levels among environments. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source] Variation in physiological health of diademed sifakas across intact and fragmented forest at Tsinjoarivo, eastern MadagascarAMERICAN JOURNAL OF PRIMATOLOGY, Issue 11 2010Mitchell T. Irwin Abstract As undisturbed habitat becomes increasingly rare, managers charged with ensuring the survival of endangered primate species must increasingly utilize disturbed and degraded habitats in species survival plans. Yet we have an imperfect understanding of the true long-term viability of primate populations in disturbed habitat, and census data can be misleading because density is not necessarily correlated with habitat quality and population viability in predictable ways. Here we present clinical laboratory data on hematology, serum biochemistry, fat-soluble vitamins, minerals, iron analytes, viral serology, and parasitology of diademed sifaka (Propithecus diadema), derived from the capture of 26 individuals spanning eight groups and two habitats (undisturbed vs. disturbed and fragmented) at Tsinjoarivo, Madagascar. Blood from fragment individuals had significantly lower values for several factors: white blood cell counts, bilirubin, total protein, albumin, calcium, sodium, chloride, manganese, zinc, iron and total iron-binding capacity. Several biochemical variables were higher in immature individuals, probably due to active growth. The large number of interhabitat differences suggests that habitat disturbance has an impact on physiological health within this population, perhaps reflecting dietary stress and/or immunosuppression. These results, combined with previous data showing altered diet, slower juvenile growth, and reduced activity in disturbed forest fragments, suggest that fragment sifakas may be less healthy than continuous forest groups. Finally, Tsinjoarivo sifakas have extremely low blood urea nitrogen (perhaps reflecting protein limitation) and selenium levels relative to other lemurs. Despite their survival and reproduction in the short term in fragments, these sifakas may represent a riskier conservation investment than conspecifics in undisturbed forest, and may be more susceptible to environmental stressors. However, more data on the fitness consequences of these biochemical differences are needed for a better interpretation of their impacts on long-term viability prospects. Am. J. Primatol. Am. J. Primatol. 72:1013,1025, 2010. © 2010 Wiley-Liss, Inc. [source] Double exposure in Mozambique's Limpopo River BasinTHE GEOGRAPHICAL JOURNAL, Issue 1 2010JULIE A SILVA This paper examines how double exposure to economic and environmental stressors , and the interaction between the two , affect smallholder farmers in Mozambique's Limpopo River Basin. Studying two case study villages we find that people, in general, are resilient to environmental stressors. However, most households show less resilience to the socioeconomic stressors and shocks that have been introduced or intensified by economic globalisation. Our findings indicate that economic change brought about by structural adjustment policies pressures rural people to alter their approach to farming, which makes it more difficult for them to respond to environmental change. For example, smallholder farmers find it difficult to make a transition to commercial farming within the Limpopo Basin, in part because farming techniques that are well adapted to managing environmental variability in the region , such as seeding many small plots , are not well suited to the economies of scale needed for profitable commercial agriculture. People use a variety of strategies to cope with interactive environmental and economic stressors and shocks, but many face considerable constraints to profitably exploiting market-based opportunities. We conclude that economic stressors and shocks may now be causing small-scale agriculture to be less well adapted to ecological and climate variability, making smallholders more vulnerable to future climate change. Some local level policy interventions, including those that support and build on local environmental knowledge, could assist rural agricultural societies in adapting to future environmental change in the context of economic globalisation. [source] Effect of unionized ammonia, viscosity and protozoan contamination on the enzyme activity of the rotifer Brachionus plicatilisAQUACULTURE RESEARCH, Issue 4 2000A B. De Araujo Substrates that are cleaved to yield fluorescent products can be used to quickly quantify enzyme activity in vivo with image analysis or in vitro with fluorometry. This study was carried out to determine whether enzyme activity in rotifers is useful for assessing the physiological condition of rotifers. Neonates of Brachionus plicatilis Müller hatched from cysts were exposed to a concentration series of unionized ammonia ranging from 0 to 9.8 p.p.m., increasing seawater viscosity relative to 1.17 to control sea water by the addition of methyl cellulose and the addition of the protozoan Euplotes sp. to a density of 40 mL,1. Rotifer glucosidase and esterase activities decreased with increasing unionized ammonia and viscosity respectively. Activities of glucosidase and phospholipase decreased with increasing protozoan contamination. There was a significant relationship between enzyme activities and rotifer population growth. In vivo activities of certain rotifer enzymes can therefore serve as biomarkers for the rapid assessment of environmental stressors in rotifer mass cultures. [source] | |||||||||||||||||||||||||