Impacts of long-term snow climate change on a high-elevation cold desert shrubland, California, USA

Ecological responses to 50-year old manipulations of snow depth and melt timing were assessed using snow fences arrayed across 50 km of a shrub–conifer landscape mosaic in eastern California, USA. We compared how increased, decreased, and ambient snow depth affected patterns of vegetation community composition, fire fuel accumulation, and annual tree ring growth. We also tested the effect of snow depth on soil carbon storage based on total C content under the two co-dominant shrub species (Artemisia tridentata and Purshia tridentata) in comparison with open, intershrub sites. Increased snow depth reduced the cover of the N-fixing shrub P. tridentata but not the water-redistributing shrub A. tridentata. Annual ring growth was greater on +snow plots and lower on ?snow plots for the conifer Pinus jeffreyi but not for Pinus contorta. Graminoid cover and aboveground biomass indicated higher fire fuel accumulation where snow depth was increased. Dead shrub stem biomass was greater regardless of whether snow depth was increased or decreased. Results demonstrate community shifts, altered tree growth, feedbacks on carbon storage, and altered fire fuel accumulation as a result of changes in snow depth and melt timing for this high-elevation, snow-dominated ecotone under future climate scenarios that envision increased or decreased snow depth.     

Validation of a Remote Sensing Model to Identify Simulium damnosum s.l. Breeding Sites in Sub-Saharan Africa

Background

Recently, most onchocerciasis control programs have begun to focus on elimination. Developing an effective elimination strategy relies upon accurately mapping the extent of endemic foci. In areas of Africa that suffer from a lack of infrastructure and/or political instability, developing such accurate maps has been difficult. Onchocerciasis foci are localized near breeding sites for the black fly vectors of the infection. The goal of this study was to conduct ground validation studies to evaluate the sensitivity and specificity of a remote sensing model developed to predict S. damnosum s.l. breeding sites.

Methodology/Principal Findings

Remote sensing images from Togo were analyzed to identify areas containing signature characteristics of S. damnosum s.l. breeding habitat. All 30 sites with the spectral signature were found to contain S. damnosum larvae, while 0/52 other sites judged as likely to contain larvae were found to contain larvae. The model was then used to predict breeding sites in Northern Uganda. This area is hyper-endemic for onchocerciasis, but political instability had precluded mass distribution of ivermectin until 2009. Ground validation revealed that 23/25 sites with the signature contained S. damnosum larvae, while 8/10 sites examined lacking the signature were larvae free. Sites predicted to have larvae contained significantly more larvae than those that lacked the signature.

Conclusions/Significance

This study suggests that a signature extracted from remote sensing images may be used to predict the location of S. damnosum s.l. breeding sites with a high degree of accuracy. This method should be of assistance in predicting communities at risk for onchocerciasis in areas of Africa where ground-based epidemiological surveys are difficult to implement.     

SLC26A4 Targeted to the Endolymphatic Sac Rescues Hearing and Balance in Slc26a4 Mutant Mice

Mutations of SLC26A4 are a common cause of human hearing loss associated with enlargement of the vestibular aqueduct. SLC26A4 encodes pendrin, an anion exchanger expressed in a variety of epithelial cells in the cochlea, the vestibular labyrinth and the endolymphatic sac. Slc26a4 ^Δ/Δ mice are devoid of pendrin and develop a severe enlargement of the membranous labyrinth, fail to acquire hearing and balance, and thereby provide a model for the human phenotype. Here, we generated a transgenic mouse line that expresses human SLC26A4 controlled by the promoter of ATP6V1B1. Crossing this transgene into the Slc26a4 ^Δ/Δ line restored protein expression of pendrin in the endolymphatic sac without inducing detectable expression in the cochlea or the vestibular sensory organs. The transgene prevented abnormal enlargement of the membranous labyrinth, restored a normal endocochlear potential, normal pH gradients between endolymph and perilymph in the cochlea, normal otoconia formation in the vestibular labyrinth and normal sensory functions of hearing and balance. Our study demonstrates that restoration of pendrin to the endolymphatic sac is sufficient to restore normal inner ear function. This finding in conjunction with our previous report that pendrin expression is required for embryonic development but not for the maintenance of hearing opens the prospect that a spatially and temporally limited therapy will restore normal hearing in human patients carrying a variety of mutations of SLC26A4.     

A distinctive fungal community inhabiting cryoconite holes on glaciers in Svalbard

Cryoconite holes on glacier surfaces are ice-cold hot spots of microbial diversity and activity but still little is known about their fungal inhabitants. We provide the first report of distinctive fungal communities in cryoconite debris from three valley glaciers at Kongsfjorden, Svalbard. Multivariate analysis of terminal-restriction fragment length polymorphism (T-RFLP) profiles of rRNA ITS amplicons revealed that quite distinct fungal communities were found in cryoconite holes compared with soils from adjacent moraine and tundra sites, and that communities on glaciers with contrasting ice-surface hydrology also differed. Most of the fungi cultured from cryoconite sediment were basidiomycetous yeasts or filamentous Ascomycota (Helotiales/Pleosporales). The latter included aeroaquatic fungi, such as Articulospora and Varicosporium, implying a role for these important freshwater decomposers in the carbon dynamics of cryoconite holes. Matching of the dominant peaks from T-RFLP analysis to predicted peaks of cultured isolates confirmed the abundance of these aeroaquatic fungi but also revealed that most of the dominant T-RFLP peaks did not match any cultured isolates. Considering the prevalence and endangerment of glacial environments worldwide, these findings would suggest that their potential as reservoirs of fungal diversity should not be overlooked.     

Antihypertensive medications and survival in patients with cancer: A population-based retrospective cohort study

Background: The association between antihypertensive medications and survival in cancer patients remains unclear. Objectives: To explore the association between classes of antihypertensive drugs and survival in cancer patients. Methods: Provincial Cancer Registry data was linked with a Provincial Drug Program Information Network (DPIN) for patients with lung (n = 4241), colorectal (n = 3967), breast (n = 4019) or prostate (n = 3355) cancer between the years of 2004 and 2008. Cox regression analyses were used to compare survival of patients using beta blockers (BBs), angiotensin-converting enzyme inhibitors/receptor blockers (ACEi/ARB), calcium channel blockers (CCBs) or thiazide diuretics (TDs) to survival of patients who did not use any of these antihypertensive drugs. Survival of patients using only one class of antihypertensive drugs were compared to each other, with BBs as the reference class. Results: Compared to the antihypertensive drug non-user cohort, BBs had no effect on survival for any of the cancers. ACEi/ARBs use was weakly associated with increased deaths for breast cancer (HR: 1.22, 95% CI: 1.04–1.44) and lung cancer (HR: 1.11, 95% CI: 1.03–1.21) patients. Deaths were also increased with CCB use in patients with breast cancer (HR: 1.22, 95% CI: 1.02–1.47) and with TD use in lung cancer patients (HR: 1.1, 95% CI: 1.01–1.19). There was strong evidence (p-value <0.0001) of an increase in deaths with TD use for colorectal (HR: 1.28, 95% CI: 1.15–1.42), and prostate (HR 1.41, 1.2–1.65) cancer patients. When including only antihypertensive drug users prescribed one drug class, lung cancer patients receiving CCBs had improved survival compared to BBs (HR 0.79, 95% CI: 0.64–0.98). Conclusions: Some classes of antihypertensive agents are associated with a decreased survival in certain cancers. The decrease could be due to more comorbidities in antihypertensive drug users. However, CCB use was associated with improved survival in lung cancer patients.