Anthropogenic and climatic factors interact to influence reproductive timing and effort.

Reproduction, although absolutely essential to a species' persistence, is in itself challenging. As anthropogenic change increasingly affects every landscape on Earth, it is critical to understand how specific pressures impact the reproductive efforts of individuals, which directly contribute to the success or failure of populations. However, organisms rarely encounter a single burden at a time, and the interactions of environmental challenges can have compounding effects. Understanding environmental and physiological pressures is difficult because they are often context-dependent and not generalizable, but long-term monitoring across variable landscapes and weather patterns can improve our understanding of these complex interactions. We tested the effects of urbanization, climate, and individual condition on the reproductive investment of wild side-blotched lizards (Uta stansburiana) by measuring physiological/reproductive metrics from six populations in urban and rural areas over six consecutive years of variable precipitation. We observed that reproductive stage affected body condition, corticosterone concentration, and oxidative stress. We also observed that reproductive patterns differed between urban and rural populations depending on rainfall, with rural animals increasing reproductive investment during rainier years compared to urban conspecifics, and that reproductive decisions appeared to occur early in the reproductive process. These results demonstrate the plastic nature of a generalist species optimizing lifetime fitness under varying conditions.

Measuring adrenal and reproductive hormones in hair from Southern Beaufort Sea polar bears (Ursus maritimus).

Polar bears (Ursus maritimus) use sea ice to access marine mammal prey. In Alaska's Southern Beaufort Sea, the declining availability of sea ice habitat in summer and fall has reduced opportunities for polar bears to routinely hunt on the ice for seals, their primary prey. This reduced access to prey may result in physiological stress with subsequent potential consequences to reproductive function (physiological changes that accompany reproduction), which can be measured via reproductive hormones. Hormone concentrations in hair can be used as a minimally invasive alternative to serum concentrations, which must come from animal captures. Hair samples also provide a long-term average measurement of hormone concentrations that is not influenced by short-term fluctuations like that of serum. The aim of this study was (1) to determine if a radioimmunoassay could be used to measure adrenal and reproductive hormones in polar bear hair, and (2) to determine what the relationship is between these hormones and other reproductive, condition, and demographic parameters of polar bears. We successfully validated this method for cortisol, progesterone, estradiol, and testosterone through the analysis of hair and serum of 141 free-ranging polar bears. We found that while hair cannot be used to estimate serum hormone concentrations during the breeding season, hormone concentrations in hair can be used to measure reproductive function in polar bears. Further, our findings support trends in previous studies measuring hormone concentrations in serum. We found that adrenal and some reproductive hormones were positively correlated in hair samples of females. Associations between hormone concentrations in hair and serum did not vary relative to reproductive status of adult females. Serum testosterone increased throughout the breeding season for adult males and was significantly associated with body mass index (BMI). Our research supports the use of hair as a measure of reproductive function in polar bears and allows us to monitor the future effects of climate change on polar bear physiology.

Comparative in vitro study of honey based and silver based wound preparations on cell viability.

BACKGROUND: Since the early 1980s a plethora of dressings has been developed to promote wound healing. The objective of this study was to compare the effects of silver based dressings and honey based dressings on cell viability. MATERIALS AND METHODS: In this blinded study, keratinocyte cultures were exposed to prepared extracts of each of the following wound dressings for 40 h: Silver based dressings: Acticoat, Actisorb, Askina, Atrauman-Ag and Contreet. Honey based dressings: Melladerm gel, Melladerm mesh, Melladerm plus and Mellarsorb. Controls consisted of cells that were cultured in the same medium, and under the same conditions as those exposed to extracts. RESULTS: All dressing extracts had an effect on cell viability. Changes in cell morphology from different wound dressing extracts were noted and compared with control groups after 24 h of incubation. CONCLUSIONS: In the silver based extracts group, Atrauman-silver and Acticoat had the most viable cells. For the honey based group, the most viable cells were seen with Melladerm mesh and Mellasorb. There was no significant difference between the best performing silver and honey based wound preparations with regard to cell viability.