49 research outputs found
Stress Responses to Heat Exposure in Three Species of Australian Desert Birds
No full textBirds need to respond to weather changes quickly and appropriately for their own well-being and survival. The inability to respond appropriately to heat waves can be fatal to individual birds and can translate into large-scale mortality events. We investigated corticosterone (CORT) and heterophil∶lymphocyte (H∶L) ratio responses of budgerigars (Melopsittacus undulatus), zebra finches (Taeniopygia guttata), and diamond doves (Geopelia cuneata) to heat exposures. The birds were exposed to a temperature similar to what they experience during a typical summer day (35˚ C) and a higher temperature (45˚ C) similar to that experienced during a heat wave. There were no significant increases between the CORT concentrations before and after heat exposure in zebra finches and budgerigars at 35˚ and 45˚ C, but there was a significant increase in CORT concentrations in diamond doves after exposure to 45˚ C. The H∶L ratios increased significantly after heat exposure in budgerigars at 35˚ and 45˚ C and in diamond doves at 35˚ C. No significant correlation was found between the changes in CORT and H∶L ratios. The data suggest that there are species differences in birds’ stress responses to heat exposure that may reflect their ability to detect and adapt to high temperatures. There appear to be differences between the two types of stress measurements, which may reflect differences in the timescales of these responses.Shangzhe Xie, L. Michael Romero, Zaw Win Htut, Todd J. McWhorte
In Vitro Regeneration of Selected Rice Genotypes (Oryza sativa L.) through Anther Culture
No full textRice is one of the most important cereal crops in the world. Anther culture, one of the double hap-loid techniques, is simple and efficient for rice breeding. The present study was carried out to evaluate callus induction ability of the selected rice genotypes on the media supplemented with two different car-bon sources and to investigate suitable Benzylaminopurine (BAP) concentrations on plant regeneration of anther-derived calli. The selected 19 rice genotypes (14 indica and 5 tropical japonica) were used in the experiment. Anthers of each genotype were cultured on Chu (N6) medium supplemented with two types of carbon sources (4% maltose and 4% sucrose), 2mg.L-1 2,4-Dichlorophenoxyacetic acid (2,4-D) and 0.5 mg.L-1 kinetin for callus induction. Anther-derived calli were transferred to Murashige and Skoog (MS) medium supplemented with (0, 0.5, 1) mg.L-1 BAP, 1 mg.L-1 1-Naphthaleneacetic acid (NAA) and 1 mg.L-1 l kinetin for regeneration. The seventeen out of 19 rice genotypes produced callus on media supplemented with maltose while only 13 genotypes produced callus on media supplemented with sucrose due to genotype dependency. Tropical japonica had more callus induction from anther than indica among the tested genotypes. Callus induction varied from 0 to 19.22%. Paw San Taung Pyan Hmwe (tropical japonica) had the highest callus induction (19.22%) among the tested all. Yebaw Sein depicted the highest callus induction (6.78%) among the tested indica rice genotypes. Plant regeneration from callus varied from 0 to 25.15%. In tropical japonica genotypes, Bay Kyar Taung Pyan gave the highest value (25.15%) in green plants regeneration, while Hnan Kar gave the highest value (13.33%) among indica genotypes. In this experiment, both MS media supplemented with 0.5mg.L-1 BAP and 1mg.L-1 BAP showed maximum green plant regeneration although maximum green spot formation oc-curred only on media supplemented with 1mg.L-1 BAP
Faecal Glucocorticoid Metabolites and H/L Ratio are Related Markers of Stress in Semi-Captive Asian Timber Elephants
No full textAnimals are kept in captivity for various reasons, but species with a slower pace of lifemay adapt to captive environments less easily, leading to welfare concerns and the need to assessstress reliably in order to develop effective interventions. Our aim was to assess welfare of semicaptivetimber elephants from Myanmar by investigating the relationship between twophysiological markers of stress commonly used as proxies for welfare, faecal glucocorticoidmetabolite concentrations (FGM) and heterophil/lymphocyte ratios (H/L), and link these measuresto changes in body condition (determined by body weight). We further assessed how robustly thesetwo markers of stress performed in animals of different age or sex, or in different ecological contexts.We measured FGM concentrations and H/L ratios between 2016 and 2018 from 316 samples of 75females and 49 males ranging in age from 4 to 68. We found a positive and consistent link betweenFGMs and H/L ratios in Asian elephants, irrespective of their sex, age, or ecological context. Ourresults will help to inform managers of (semi-) captive elephants about using heterophil/lymphocyteratio data from blood smears on site as a potentially cheaper and faster alternative to determiningstress than measuring faecal glucocorticoid metabolite concentrations in the laboratory.</p
Faecal Glucocorticoid Metabolites and H/L Ratio Are Related Markers of Stress in Semi-Captive Asian Timber Elephants
No full textAnimals are kept in captivity for various reasons, but species with a slower pace of life may adapt to captive environments less easily, leading to welfare concerns and the need to assess stress reliably in order to develop effective interventions. Our aim was to assess welfare of semi-captive timber elephants from Myanmar by investigating the relationship between two physiological markers of stress commonly used as proxies for welfare, faecal glucocorticoid metabolite concentrations (FGM) and heterophil/lymphocyte ratios (H/L), and link these measures to changes in body condition (determined by body weight). We further assessed how robustly these two markers of stress performed in animals of different age or sex, or in different ecological contexts. We measured FGM concentrations and H/L ratios between 2016 and 2018 from 316 samples of 75 females and 49 males ranging in age from 4 to 68. We found a positive and consistent link between FGMs and H/L ratios in Asian elephants, irrespective of their sex, age, or ecological context. Our results will help to inform managers of (semi-) captive elephants about using heterophil/lymphocyte ratio data from blood smears on site as a potentially cheaper and faster alternative to determining stress than measuring faecal glucocorticoid metabolite concentrations in the laboratory
Assesment on the genetic diversity of some Myanmar cucumber (Cucumis sativus L.) landraces
No full textSex-specific links between the social landscape and faecal glucocorticoid metabolites in semi-captive Asian elephants
No full textAlthough social behaviour is common in group-living mammals, our understanding of its mechanisms in long-lived animals is largely based on studies in human and non-human primates. There are health and fitness benefits associated with strong social ties, including increased life span, reproductive success, and lower disease risk, which are attributed to the proximate effects of lowered circulating glucocorticoid hormones. However, to deepen our understanding of health-social dynamics, we must explore species beyond the primate order. Here, using Asian elephants as a model species, we combine social data generated from semi-captive timber elephants in Myanmar with measurements of faecal glucocorticoid metabolite (FGM) concentrations. These data enable a “natural experiment” because individuals live in work groups with different demographic compositions. We examine sex-specific FGM concentrations for four different aspects of an individuals’ social world: general sociality, work group size, sex ratio and the presence of immatures (<5 years) within the work group. Males experienced lower FGM concentrations when engaged in more social behaviours and residing in female-biased work groups. Surprisingly, females only exhibited lower FGM concentrations when residing with calves. Together, our findings highlight the importance of sociality on individual physiological function among elephants, which may have broad implications for the benefits of social interactions among mammals.</p
Sex-specific links between the social landscape and faecal glucocorticoid metabolites in semi-captive Asian elephants
No full textAlthough social behaviour is common in group-living mammals, our understanding of its mechanisms in long-lived animals is largely based on studies in human and non-human primates. There are health and fitness benefits associated with strong social ties, including increased life span, reproductive success, and lower disease risk, which are attributed to the proximate effects of lowered circulating glucocorticoid hormones. However, to deepen our understanding of health-social dynamics, we must explore species beyond the primate order. Here, using Asian elephants as a model species, we combine social data generated from semi-captive timber elephants in Myanmar with measurements of faecal glucocorticoid metabolite (FGM) concentrations. These data enable a "natural experiment" because individuals live in work groups with different demographic compositions. We examine sex-specific FGM concentrations for four different aspects of an individuals' social world: general sociality, work group size, sex ratio and the presence of immatures (< 5 years) within the work group. Males experienced lower FGM concentrations when engaged in more social behaviours and residing in female-biased work groups. Surprisingly, females only exhibited lower FGM concentrations when residing with calves. Together, our findings highlight the importance of sociality on individual physiological function among elephants, which may have broad implications for the benefits of social interactions among mammals.</p
A standardised faecal collection protocol for intestinal helminth egg counts in Asian elephant, Elephas maximus
No full textThe quantitative assessment of parasite infection is necessary to measure, manage and reduce infection risk in both wild and captive animal populations. Traditional faecal flotation methods which aim to quantify parasite burden, such as the McMaster egg counting technique, are widely used in veterinary medicine, agricultural management and wildlife parasitology. Although many modifications to the McMaster method exist, few account for systematic variation in parasite egg output which may lead to inaccurate estimations of infection intensity through faecal egg counts (FEC). To adapt the McMaster method for use in sampling Asian elephants (Elephas maximus), we tested a number of possible sources of error regarding faecal sampling, focussing on helminth eggs and using a population of over 120 semi-captive elephants distributed across northern Myanmar. These included time of day of defecation, effects of storage in 10% formalin and 10% formol saline and variation in egg distribution between and within faecal boluses. We found no significant difference in the distribution of helminth eggs within faecal matter or for different defecation times, however, storage in formol saline and formalin significantly decreased egg recovery. This is the first study to analyse several collection and storage aspects of a widely-used traditional parasitology method for helminth parasites ofE.maximususing known host individuals. We suggest that for the modified McMaster technique, a minimum of one fresh sample per elephant collected from any freshly produced bolus in the total faecal matter and at any point within a 7.5h time period (7.30am–2.55pm) will consistently represent parasite load. This study defines a protocol which may be used to test pre-analytic factors and effectively determine infection load in species which produce large quantities of vegetative faeces, such as non-ruminant megaherbivores
Seasonal variation in molecular and physiological stress markers in Asian elephants
No full textFree-living species exhibit seasonal variation in various life history traits, including vital rates such as birth and death patterns. Different physiological mechanisms are thought to underlie the expression of life history traits that contribute to lifetime fitness. However, although the broad impacts of seasonality on life history traits and trade-offs is well established in many systems, the exact physiological mechanisms responsible for driving differences within and between individuals are poorly understood. Among them, molecular and physiological stress pathways, such as stress hypothalamic-pituitary-adrenal axis and oxidative stress, have potential to mediate relationships between individual survival, reproduction and environmental seasonality. Here, we determine how different physiological markers of stress including faecal cortisol metabolites (FCMs), heterophils/lymphocytes (H/L) ratio, two markers indicating oxidative balance including a marker of oxidative damage (reactive oxygen metabolites, ROM) and a marker of antioxidant defences (superoxide dismutase, SOD) and body weight vary in a large semi-captive population of Asian elephants (Elephas maximus) exposed to extreme seasonality (e.g. elevated temperatures). Individuals showed higher FCM levels and H/L ratios during cold season, indicating increased stress, and the lowest FCM levels during monsoon season and H/L ratios during hot and dry season, but we found no pattern in oxidative stress (ROM and SOD) levels. Hot season also associated with a decline in body weight. The present study shows how different physiological parameters (FCM levels and H/L ratio), molecular (oxidative stress) and body condition vary with seasonal changes, and how these parameters might allow individuals to adapt to such variations. Our results on an endangered long-lived species are crucial in indicating the most productive timing for conservation efforts, predicting how individuals cope with environmental changes, and allow for a more accurate representation of how animal physiology operates in nature
Serum-Mediated Cleavage of <italic toggle="yes">Bacillus anthracis</italic> Protective Antigen Is a Two-Step Process That Involves a Serum Carboxypeptidase
No full textABSTRACT Much of our understanding of the activity of anthrax toxin is based on in vitro systems, which delineate the interaction between Bacillus anthracis toxins and the cell surface. However, these systems fail to account for the intimate association of B. anthracis with the circulatory system, including the contribution of serum proteins to the host response and processing of anthrax toxins. Using a variety of immunological techniques to inhibit serum processing of B. anthracis protective antigen (PA) along with mass spectrometry analysis, we demonstrate that serum digests PA via 2 distinct reactions. In the first reaction, serum cleaves PA83 into 2 fragments to produce PA63 and PA20 fragments, similarly to that observed following furin digestion. This is followed by carboxypeptidase-mediated removal of the carboxy-terminal arginine and lysines from PA20. IMPORTANCE Our findings identify a serum-mediated modification of PA20 that has not been previously described. These observations further imply that the processing of PA is more complex than currently thought. Additional study is needed to define the contribution of serum processing of PA to the host response and individual susceptibility to anthrax
