Liquid droplet formation by HP1α suggests a role for phase separation in heterochromatin.

Gene silencing by heterochromatin is proposed to occur in part as a result of the ability of heterochromatin protein 1 (HP1) proteins to spread across large regions of the genome, compact the underlying chromatin and recruit diverse ligands. Here we identify a new property of the human HP1α protein: the ability to form phase-separated droplets. While unmodified HP1α is soluble, either phosphorylation of its N-terminal extension or DNA binding promotes the formation of phase-separated droplets. Phosphorylation-driven phase separation can be promoted or reversed by specific HP1α ligands. Known components of heterochromatin such as nucleosomes and DNA preferentially partition into the HP1α droplets, but molecules such as the transcription factor TFIIB show no preference. Using a single-molecule DNA curtain assay, we find that both unmodified and phosphorylated HP1α induce rapid compaction of DNA strands into puncta, although with different characteristics. We show by direct protein delivery into mammalian cells that an HP1α mutant incapable of phase separation in vitro forms smaller and fewer nuclear puncta than phosphorylated HP1α. These findings suggest that heterochromatin-mediated gene silencing may occur in part through sequestration of compacted chromatin in phase-separated HP1 droplets, which are dissolved or formed by specific ligands on the basis of nuclear context

One session of TTM-tailored condom use feedback: a pilot study among at-risk women in the Bronx

There is an urgent need to implement interventions to curb the spread of sexually transmitted infections (STIs), especially HIV. Consistent condom use is an effective preventive strategy, yet especially among those at highest risk, condom use remains too low. This paper describes changes in condom use and stages of condom use over two–three months time following a single session with an interactive multimedia computer-delivered Transtheoretical Model (TTM)-tailored expert system originally designed for at-risk adolescents. The intervention provided immediate TTM-tailored feedback to diverse urban women based on their stage of condom use and other TTM variables. Previous work found this system was acceptable. These data showed that 89% of women returned for a second session two–three months later, further supporting this system\u27s utility. After just one feedback session, 21% of women not using condoms at baseline started using condoms consistently at follow-up, with a trend for a relationship to baseline stage of condom use. These results support further randomized controlled research on the reach and efficacy of computer-based TTM-tailored and individualized condom use interventions

Stages of Change for Voluntary Medical Male Circumcision and Sexual Risk Behavior in Uncircumcised Zambian Men: The Spear and Shield Project

Background: Dissemination and scale up of voluntary medical male circumcision (VMMC) programs is well supported by evidence that VMMC reduces HIV risk in populations with high HIV prevalence and low rates of circumcision, as is the case in Zambia. Purpose: At both individual and population levels, it is important to understand what stages of change for VMMC are associated with, especially across cultures. This study evaluated VMMC knowledge, misinformation, and stages of change for VMMC of uncircumcised men and boys (over 18 years), as well as the concurrent relationship between VMMC stages of change and sexual risk behaviors. Method: Uncircumcised (N = 800) adult men and boys (over 18) were screened and recruited from urban community health centers in Lusaka, Zambia, where they then completed baseline surveys assessing knowledge, attitudes, HIV risk behaviors, and stages of change for VMMC. A series of analyses explored cross-sectional relationships among these variables. Results: VMMC was culturally acceptable in half of the sample; younger, unmarried, and more educated men were more ready to undergo VMMC. Stage of change for VMMC was also related to knowledge, and those at greater HIV risk reported greater readiness to undergo VMMC. Conclusions: Efforts to increase VMMC uptake should address the role of perceived HIV risk, risk behaviors, readiness, accurate knowledge, cultural acceptance, and understanding of the significant degree of HIV protection conferred as part of the VMMC decision making process. These results support incorporating comprehensive HIV risk reduction in VMMC promotion programs

Female Partner Acceptance as a Predictor of Men’s Readiness to Undergo Voluntary Medical Male Circumcision in Zambia: The Spear and Shield Project

The World Health Organization has recommended the scale-up of voluntary medical male circumcision (VMMC) for HIV prevention in sub-Saharan Africa; however, men are often uninterested in undergoing VMMC. The Spear & Shield project enrolled 668 men and female partners from ten Zambian community health centers into parallel interventions promoting VMMC for HIV prevention or time-matched control conditions. A mediation model was utilized to examine the relationships between changes in women’s acceptance of VMMC and men’s readiness to undergo the procedure. Results demonstrated that, at 12 months post-intervention, a 5.9 % increase in the likelihood of undergoing VMMC among men in the experimental condition could be attributed to increased women’s acceptance. From a public health perspective, involving women in VMMC promotion interventions such as the Spear & Shield project could significantly impact the demand for VMMC in Zambia

Evaluation of the acceptability and feasibility of a computer-tailored intervention to increase HPV vaccination among young adult women

Objective: To examine acceptability and feasibility of a Transtheoretical Model (TTM)-based computer-tailored intervention for increasing HPV vaccination in college-aged women. Participants: 243 women ages 18-26 were recruited between February and May of 2011. Methods: Participants completed the intervention and a 14-item evaluation of intervention content and delivery. Results: Most participants had heard of HPV (91%), but the majority (57%) of participants were in Precontemplation for getting vaccinated. Eighty nine percent of participants rated the CTI positively across all acceptability items, and 91% endorsed intention to get vaccinated after intervention. While average ratings in each demographic subgroup were positive, Hispanic women and participants in more advanced Stages of Change rated the program more favorably than non-Hispanic and earlier stage participants. Additionally, HPV Knowledge was higher among White/Non-Hispanic participants. Conclusions: Initial acceptability and feasibility data for this intervention is promising. Its computer-based, individually-tailored format is state of the art and ideal for inexpensive dissemination

Functional responses of methanogenic archaea to syntrophic growth.

Methanococcus maripaludis grown syntrophically with Desulfovibrio vulgaris was compared with M. maripaludis monocultures grown under hydrogen limitation using transcriptional, proteomic and metabolite analyses. These measurements indicate a decrease in transcript abundance for energy-consuming biosynthetic functions in syntrophically grown M. maripaludis, with an increase in transcript abundance for genes involved in the energy-generating central pathway for methanogenesis. Compared with growth in monoculture under hydrogen limitation, the response of paralogous genes, such as those coding for hydrogenases, often diverged, with transcripts of one variant increasing in relative abundance, whereas the other was little changed or significantly decreased in abundance. A common theme was an apparent increase in transcripts for functions using H(2) directly as reductant, versus those using the reduced deazaflavin (coenzyme F(420)). The greater importance of direct reduction by H(2) was supported by improved syntrophic growth of a deletion mutant in an F(420)-dependent dehydrogenase of M. maripaludis. These data suggest that paralogous genes enable the methanogen to adapt to changing substrate availability, sustaining it under environmental conditions that are often near the thermodynamic threshold for growth. Additionally, the discovery of interspecies alanine transfer adds another metabolic dimension to this environmentally relevant mutualism

Impacts of environmental and socio-economic factors on emergence and epidemic potential of Ebola in Africa

Abstract: Recent outbreaks of animal-borne emerging infectious diseases have likely been precipitated by a complex interplay of changing ecological, epidemiological and socio-economic factors. Here, we develop modelling methods that capture elements of each of these factors, to predict the risk of Ebola virus disease (EVD) across time and space. Our modelling results match previously-observed outbreak patterns with high accuracy, and suggest further outbreaks could occur across most of West and Central Africa. Trends in the underlying drivers of EVD risk suggest a 1.75 to 3.2-fold increase in the endemic rate of animal-human viral spill-overs in Africa by 2070, given current modes of healthcare intervention. Future global change scenarios with higher human population growth and lower rates of socio-economic development yield a 1.63-fold higher likelihood of epidemics occurring as a result of spill-over events. Our modelling framework can be used to target interventions designed to reduce epidemic risk for many zoonotic diseases

Star formation history in the SMC: the case of NGC602

Deep HST/ACS photometry of the young cluster NGC 602, located in the remote low density "wing" of the Small Magellanic Cloud, reveals numerous pre-main sequence stars as well as young stars on the main sequence. The resolved stellar content thus provides a basis for studying the star formation history into recent times and constraining several stellar population properties, such as the present day mass function, the initial mass function and the binary fraction. To better characterize the pre-main sequence population, we present a new set of model stellar evolutionary tracks for this evolutionary phase with metallicity appropriate for the Small Magellanic Cloud (Z = 0.004). We use a stellar population synthesis code, which takes into account a full range of stellar evolution phases to derive our best estimate for the star formation history in the region by comparing observed and synthetic color-magnitude diagrams. The derived present day mass function for NGC 602 is consistent with that resulting from the synthetic diagrams. The star formation rate in the region has increased with time on a scale of tens of Myr, reaching $0.3-0.7 \times 10^{-3} M_\odot yr^{-1}$ in the last 2.5 Myr, comparable to what is found in Galactic OB associations. Star formation is most complete in the main cluster but continues at moderate levels in the gas-rich periphery of the nebula.Comment: 24 pages. Accepted for publication in A