Possible impact of climate and environmental change on ticks and tick-borne disease in England.

The survival, density and distribution of ticks are determined by three key elements: microclimate, habitat and host, all of which can be impacted by climate change. The public health risk from ticks is further influenced by human behaviour and the way in which we access and manage the environment where ticks or key tick hosts are found. This expert opinion considers how these factors influence tick-borne disease (TBD) transmission in a changing climate, first by discussing direct effects of climate change on ticks and TBD, and second the indirect effects and environmental changes that make direct comparisons of climate and ticks so challenging.

Improvement of the in vitro growth and maturation of isolated mouse preantral follicles in the presence of repaglinide

The development of in vitro culture systems that result to preantral follicles growth and increasing of developmental competency of oocytes obtained from follicles has an important role in fertility preservation and assisted reproductive techniques. In this research, we evaluated the effect of repaglinide on in vitro growth and maturation of preantral follicles. Preantral follicles were isolated from 12-14 day-old female NMRI mice ovaries and cultured for 12 days cultured in α-MEM (Control), α-MEM supplemented with 1µM of repaglinide. Follicles examined for development on 1, 3, 6, 9, 12 days of culture. At the end of culture period after HCG administration in vitro oocyte maturation was assessed. Results showed that in vitro follicle growth, survival, density of granulosa cells and steroidogenic activity were higher than the control group (p less than 0.05). In vitro maturation rate in oocytes derived from follicles in the treatment group was higher than control group (p less than 0.05). Therefore the supplementation of the culture medium with repaglinide can improve the ovarian follicle survival, growth and subsequently in vitro oocyte maturation.

Population demography of Oldham’s leaf turtle (Cyclemys oldhamii) in protected and disturbed habitats in Thailand

Background Freshwater turtle populations are vulnerable to a range of human activities because of particular life history attributes, and anthropogenic impacts can cause shifts in demographic traits, including survival, density and population structure. Asian freshwater turtles have undergone dramatic population declines in recent decades principally because of collection for food, pet, and traditional medicine markets. Despite this, few studies have been conducted on the population demography of these turtles, thereby limiting our understanding of population trends and the development of conservation actions. Oldham’s leaf turtle (Cyclemys oldhamii) is one of the most commonly traded turtles in Asian markets, but previous published studies have focused solely on systematics. Methods We conducted a mark-recapture study of C. oldhamii at three sites in northeastern Thailand—a protected stream, a degraded stream, and human-constructed ponds—and evaluated differences in survival, density, population structure, and sexual dimorphism among sites. Results We captured 77 turtles at the protected stream, 67 at the constructed ponds, and two in the degraded stream. Survival was 12% lower and density was 35% lower in the constructed ponds than in the protected stream. Size class structure was skewed toward smaller individuals at the constructed ponds, and both sites exhibited subadult-skewed age class structure. Sex ratios were not statistically different than 1:1 at either site and did not differ between sites. We did not document sexual dimorphism in either population. Discussion Explanations for lower survival, lower densities, and skewed size class structure at the constructed ponds include collection for consumption or Buddhist prayer release locally, collection for illegal export from Thailand, predation by domestic dogs associated with humans living nearby, or lower habitat quality. Evidence from our study suggests that collection, either for local use or export, is the most likely explanation for differences in demographic characteristics between the two sites. The information gained from this study may contribute to a status assessment for C. oldhamii and development of conservation actions should they become necessary to protect populations in Thailand.

Inhibition of Hippocampal Regeneration by Adjuvant Dexamethasone in Experimental Infant Rat Pneumococcal Meningitis

Pneumococcal meningitis (PM) causes neurological sequelae in up to half of surviving patients. Neuronal damage associated with poor outcome is largely mediated by the inflammatory host response. Dexamethasone (DXM) is used as an adjuvant therapy in adult PM, but its efficacy in the treatment of pneumococcal meningitis in children is controversially discussed. While DXM has previously been shown to enhance hippocampal apoptosis in experimental PM, its impact on hippocampal cell proliferation is not known. This study investigated the impact of DXM on hippocampal proliferation in infant rat PM. Eleven-day-old nursing Wistar rats (n= 90) were intracisternally infected withStreptococcus pneumoniaeto induce experimental meningitis. Treatment with DXM or vehicle was started 18 h after infection, concomitantly with antibiotics (ceftriaxone 100 mg/kg of body weight twice a day [b.i.d.]). Clinical parameters were monitored, and the amount of cells with proliferating activity was assessed usingin vivoincorporation of bromodeoxyuridine (BrdU) and anin vitroneurosphere culture system at 3 and 4 d postinfection. DXM significantly worsened weight loss and survival. Density of BrdU-positive cells, as an index of cells with proliferating activity, was significantly lower in DXM-treated animals compared to vehicle controls (P< 0.0001). In parallel, DXM reduced neurosphere formation as an index for stem/progenitor cell density compared to vehicle treatment (P= 0.01). Our findings provide clear evidence that DXM exerts an antiproliferative effect on the hippocampus in infant rat PM. We conclude that an impairment of regenerative hippocampal capacity should be taken into account when considering adjuvant DXM in the therapeutic regimen for PM in children.

Effect of microsites on the survival, density, and ectomycorrhizal status of shade-tolerant Abies alba regeneration attacked by fungal pathogens

An increased incidence of fungal pathogens has been recognized as one of the most important causes for insufficient natural regeneration in pure Abies alba Mill. forests in the Western Carpathians (central Europe). We investigated the spatial distribution of A. alba seedlings in seven stands in which severe symptoms of fungal pathogen infections were observable and compared microsite variables and ectomycorrhizal status of seedlings in locations with abundant or poor regeneration. We also tested the effect of local stand density, seedbed, and vegetation control on seed germination and the survival of 1-year seedlings. The study provided evidence that gap environment may increase the mortality of 1-year seedlings caused by fungal pathogens. That pattern was consistent with the spatial distribution of older seedlings: locations with abundant older regeneration were characterized by a greater local stand density, lower canopy openness, and lower mineral topsoil moisture than poorly regenerated locations. Yet, despite considerable spatial differentiation in ectomycorrhizal types, the mycorrhizal status of 2-year seedlings in abundantly regenerated areas did not differ from that in poorly regenerated areas.

Effects of Snail Density on Growth, Reproduction and Survival ofBiomphalaria alexandrinaExposed toSchistosoma mansoni

The effects of snail density onBiomphalaria alexandrinaparasitized withSchistosoma mansoniwere investigated. Laboratory experiments were used to quantify the impact of high density on snail growth, fecundity, and survival. Density-dependent birth rates of snails were determined to inform mathematical models, which, until now, have assumed a linear relationship between density and fecundity. The experiments show that the rate of egg-laying followed a negative exponential distribution with increasing density and this was significantly affected by exposure to parasitic infection. High density also affected the weight of snails and survival to a greater degree than exposure to parasitic infection. Although snail growth rates were initially constrained by high density, they retained the potential for growth suggesting a reversible density-dependent mechanism. These experimental data can be used to parameterise models and confirm that snail populations are regulated by nonlinear density-dependent mechanisms.

Large fires as agents of ecological diversity in the North American boreal forest

The present study undertook a hierarchical analysis of the variability within and among some individual fire events in the boreal ecozones of Canada and Alaska. When stratified by ecozone, differences in the spatial and temporal distribution of wildfires were observed in the Canadian Large Fire Data Base that reflect climatic, terrain and land-use differences across the country. Remote-sensing data collected before and after boreal forest fires permitted a rigorous analysis of the variability in burn severity within individual fire events, and the identification of certain fire-prone and more fire-resistant land-cover types. The occurrence of fire skips or islands was related to the distribution of those cover types, resulting in proportionally more unburned area within the perimeter of a burn for larger fires. Differences in burn severity led to differences in post-burn vegetation response of tree, shrub and moss layers that can persist for decades or even centuries. As a result, there can be considerable variability in the survival, density and distribution of residual biota and organic materials. This variability creates a range of post-fire vegetation patterns and contributes much to the habitat diversity of boreal landscapes.