Population structure over a broad spatial scale driven by nonanthropogenic factors in a wide‐ranging migratory mammal,Alaskan caribou

Wide‐ranging mammals face significant conservation threats, and knowledge of the spatial scale of population structure and its drivers is needed to understand processes that maintain diversity in these species. We analysed DNA from 655 Alaskan caribou (Rangifer tarandus granti) from 20 herds that vary in population size, used 19 microsatellite loci to document genetic diversity and differentiation in Alaskan caribou, and examined the extent to which genetic differentiation was associated with hypothesized drivers of population subdivision including landscape features, population size and ecotype. We found that Alaskan caribou are subdivided into two hierarchically structured clusters: one group on the Alaska Peninsula containing discrete herds and one large group on the Mainland lacking differentiation between many herds. Population size, geographic distance, migratory ecotype and the Kvichak River at the nexus of the Alaska Peninsula were associated with genetic differentiation. Contrary to previous hypotheses, small Mainland herds were often differentiated genetically from large interconnected herds nearby, and genetic drift coupled with reduced gene flow may explain this pattern. Our results raise the possibility that behaviour helps to maintain genetic differentiation between some herds of different ecotypes. Alaskan caribou show remarkably high diversity and low differentiation over a broad geographic scale. These results increase information for the conservation of caribou and other migratory mammals threatened by population reductions and landscape barriers and may be broadly applicable to understanding the spatial scale and ecological drivers of population structure in widespread species.     

Consequences of a Government-Controlled Agricultural Price Increase on Fishing and the Coral Reef Ecosystem in the Republic of Kiribati

Background

Economic development policies may have important economic and ecological consequences beyond the sector they target. Understanding these consequences is important to improving these policies and finding opportunities to align economic development with natural resource conservation. These issues are of particular interest to governments and non-governmental organizations that have new mandates to pursue multiple benefits. In this case study, we examined the direct and indirect economic and ecological effects of an increase in the government-controlled price for the primary agricultural product in the Republic of Kiribati, Central Pacific.

Methods/Principal Findings

We conducted household surveys and underwater visual surveys of the coral reef to examine how the government increase in the price of copra directly affected copra labor and indirectly affected fishing and the coral reef ecosystem. The islands of Kiribati are coral reef atolls and the majority of households participate in copra agriculture and fishing on the coral reefs. Our household survey data suggest that the 30% increase in the price of copra resulted in a 32% increase in copra labor and a 38% increase in fishing labor. Households with the largest amount of land in coconut production increased copra labor the most and households with the smallest amount of land in coconut production increased fishing the most. Our ecological data suggests that increased fishing labor may result in a 20% decrease in fish stocks and 4% decrease in coral reef-builders.

Conclusions/Significance

We provide empirical evidence to suggest that the government increase in the copra price in Kiribati had unexpected and indirect economic and ecological consequences. In this case, the economic development policy was not in alignment with conservation. These results emphasize the importance of accounting for differences in household capital and taking a systems approach to policy design and evaluation, as advocated by sustainable livelihood and ecosystem-based management frameworks.     

Efficacy of Enhanced HIV Counseling for Risk Reduction during Pregnancy and in the Postpartum Period: A Randomized Controlled Trial

Introduction

Pregnancy and the postpartum period present important intervention opportunities. Counseling can leverage the motivation women have during this time to change behaviors that may negatively affect their health and the heath of their infants.

Methods

Pregnant women attending an antenatal clinic in South Africa were randomly allocated to treatment (n = 733) and control arms (n = 747). Treatment arm participants received enhanced HIV pre- and post-test counseling, legal support and access to support groups at baseline, which occurred at the first antenatal visit, and then six and ten weeks postpartum. Control arm participants received standard HIV testing and counseling (HTC) and two postpartum attention control sessions. Outcomes were incidence of sexually transmitted infection (STI) by 14 weeks postpartum and past 30-day inconsistent condom use at 14 weeks and 9 months postpartum.

Results

There were no intervention effects on incident STIs for either HIV-negative (adjusted risk ratio (aRR) 1.01, 95% CI 0^.71–1^.44) or HIV-positive participants (aRR 0^.86, 95% CI 0^.61–1^.23). The intervention was associated with a 28% decrease in risk of past 30-day inconsistent condom use at nine-months among HIV-negative women (aRR 0^.72,95% CI 0^.59–0^.88), but did not affect inconsistent condom use among HIV-positive women (aRR1.08; 95% CI 0.67–1.75).

Discussion

An enhanced counseling intervention during pregnancy and the postpartum period can lead to reductions in inconsistent condom use among HIV-negative women. Results underscore the importance of the counseling that accompanies HIV HTC. More work is needed to understand how to promote and sustain risk reduction among HIV-positive women.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01683461","term_id":"NCT01683461"}}NCT01683461     

Genetic Structure and Molecular Variability of Cucumber mosaic virus Isolates in the United States

Cucumber mosaic virus (CMV) has a worldwide distribution and the widest host range of any known plant virus. From 2000 to 2012, epidemics of CMV severely affected the production of snap bean (Phaseulos vulgaris L.) in the Midwest and Northeastern United States. Virus diversity leading to emergence of new strains is often considered a significant factor in virus epidemics. In addition to epidemics, new disease phenotypes arising from genetic exchanges or mutation can compromise effectiveness of plant disease management strategies. Here, we captured a snapshot of genetic variation of 32 CMV isolates collected from different regions of the U.S including new field as well as historic isolates. Nucleotide diversity (π) was low for U.S. CMV isolates. Sequence and phylogenetic analyses revealed that CMV subgroup I is predominant in the US and further showed that the CMV population is a mixture of subgroups IA and IB. Furthermore, phylogenetic analysis suggests likely reassortment between subgroups IA and IB within five CMV isolates. Based on phylogenetic and computational analysis, recombination between subgroups I and II as well as IA and IB in RNA 3 was detected. This is the first report of recombination between CMV subgroups I and II. Neutrality tests illustrated that negative selection was the major force operating upon the CMV genome, although some positively selected sites were detected for all encoded proteins. Together, these data suggest that different regions of the CMV genome are under different evolutionary constraints. These results also delineate composition of the CMV population in the US, and further suggest that recombination and reassortment among strain subgroups does occur but at a low frequency, and point towards CMV genomic regions that differ in types of selection pressure.     

Stimulators of Mineralization Limit the Invasive Phenotype of Human Osteosarcoma Cells by a Mechanism Involving Impaired Invadopodia Formation

Background

Osteosarcoma (OS) is a highly aggressive bone cancer affecting children and young adults. Growing evidence connects the invasive potential of OS cells with their ability to form invadopodia (structures specialized in extracellular matrix proteolysis).

Results

In this study, we tested the hypothesis that commonly used in vitro stimulators of mineralization limit the invadopodia formation in OS cells. Here we examined the invasive potential of human osteoblast-like cells (Saos-2) and osteolytic-like (143B) OS cells treated with the stimulators of mineralization (ascorbic acid and B-glycerophosphate) and observed a significant difference in response of the tested cells to the treatment. In contrast to 143B cells, osteoblast-like cells developed a mineralization phenotype that was accompanied by a decreased proliferation rate, prolongation of the cell cycle progression and apoptosis. On the other hand, stimulators of mineralization limited osteolytic-like OS cell invasiveness into collagen matrix. We are the first to evidence the ability of 143B cells to degrade extracellular matrix to be driven by invadopodia. Herein, we show that this ability of osteolytic-like cells in vitro is limited by stimulators of mineralization.

Conclusions

Our study demonstrates that mineralization competency determines the invasive potential of cancer cells. A better understanding of the molecular mechanisms by which stimulators of mineralization regulate and execute invadopodia formation would reveal novel clinical targets for treating osteosarcoma.     

Optical techniques for imaging membrane topography

In recent years three powerful optical imaging techniques have emerged that provide nanometer-scale information about the topography of membrane surfaces, whether cellular or artificial: intermembrane fluorescence resonance energy transfer (FRET), fluorescence interference contrast microscopy (FLIC), and reflection interference contrast microscopy (RICM). In intermembrane FRET, the sharp distance dependence of resonant energy transfer between fluorophores allows topographic measurements in the Angstrom to few-nanometer range. In FLIC and RICM, interference between light from a membrane (either from fluorescent probes, or reflected illumination) and light reflected by a planar substrate provide spatial sensitivity in the few to hundreds of nanometer range, with few-nanometer resolution. All of these techniques are fairly easy to implement. We discuss the physics and optics behind each of these tools, as well as practical concerns regarding their uses. We also provide examples of their application in imaging molecular-scale structures at intermembrane junctions.     

Generation and Culture of Blood Outgrowth Endothelial Cells from Human Peripheral Blood

Historically, the limited availability of primary endothelial cells from patients with vascular disorders has hindered the study of the molecular mechanisms underlying endothelial dysfunction in these individuals. However, the recent identification of blood outgrowth endothelial cells (BOECs), generated from circulating endothelial progenitors in adult peripheral blood, may circumvent this limitation by offering an endothelial-like, primary cell surrogate for patient-derived endothelial cells. Beyond their value to understanding endothelial biology and disease modeling, BOECs have potential uses in endothelial cell transplantation therapies. They are also a suitable cellular substrate for the generation of induced pluripotent stem cells (iPSCs) via nuclear reprogramming, offering a number of advantages over other cell types. We describe a method for the reliable generation, culture and characterization of BOECs from adult peripheral blood for use in these and other applications. This approach (i) allows for the generation of patient-specific endothelial cells from a relatively small volume of adult peripheral blood and (ii) produces cells that are highly similar to primary endothelial cells in morphology, cell signaling and gene expression.