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

Public health nutrition and sustainability

In public health nutrition, sustainability refers to the ability to maintain food system capacity to support the nutritional health needs of current and future populations while protecting the ecological systems that produce food. The FAO defines sustainable diets as those that are ‘protective and respectful of biodiversity and ecosystems, culturally acceptable, accessible, economically fair and affordable; nutritionally adequate, safe and healthy; while optimizing natural and human resources’

Transformation Toughening in Ceramics

The origin of transformation toughening in ceramics is examined using two separate approaches: one based on the stress field ahead of the crack and the other on the changes in thermodynamic potential during a crack increment. Both approaches yield essentially similar predictions of trends in toughness with particle size, temperature, composition, etc. The stress intensity analysis provides fully quantitative predictions of the toughness. These indicate that the shielding of the crack by the transformation zone only develops in the presence of a transformed wake, leading to R-curve behavior

The organic geochemistry of ancient sediments, part II

Chemical analysis of sediment and oil hydrocarbon content by gas chromatography and mass spectrometry to establish inception period of bio-organic evolutio

Sustainable diets and biodiversity: Directions and solutions for policy, research and action

This book presents the current state of thought on the common path of sustainable diets and biodiversity. It consists of 4 chapters which look at sustainable diets and biodiversity through sustainable food production and consumption which is illustrated with ten cases studies. The final chapter deals more specifically with the example of the Mediterranean diet. The book resulted from an International Scientific Symposium “Biodiversity and Sustainable Diets: United Against Hunger” organized jointly by FAO and Bioversity International, held at FAO, in Rome, from 3 to 5 November 2010, within the World Food Day/Week programme, on the occasion of the 2010 International Year of Biodiversity. Book by chapters: Introduction Chapter 1 - SUSTAINABLE DIETS AND BIODIVERSITYChapter 2 - SUSTAINABLE FOOD PRODUCTION AND CONSUMPTIONChapter 3 - CASE STUDIES: BRINGING BIODIVERSITY TO THE PLATEChapter 4 - AN EXAMPLE OF A SUSTAINABLE DIET: THE MEDITERRANEAN DIE

Lunar Outgassing, Transient Phenomena and The Return to The Moon, I: Existing Data

Herein the transient lunar phenomena (TLP) report database is subjected to a discriminating statistical filter robust against sites of spurious reports, and produces a restricted sample that may be largely reliable. This subset is highly correlated geographically with the catalog of outgassing events seen by the Apollo 15, 16 and Lunar Prospector alpha-particle spectrometers for episodic Rn-222 gas release. Both this robust TLP sample and even the larger, unfiltered sample are highly correlated with the boundary between mare and highlands, as are both deep and shallow moonquakes, as well as Po-210, a long-lived product of Rn-222 decay and a further tracer of outgassing. This offers another significant correlation relating TLPs and outgassing, and may tie some of this activity to sagging mare basalt plains (perhaps mascons). Additionally, low-level but likely significant TLP activity is connected to recent, major impact craters (while moonquakes are not), which may indicate the effects of cracks caused by the impacts, or perhaps avalanches, allowing release of gas. The majority of TLP (and Rn-222) activity, however, is confined to one site that produced much of the basalt in the Procellarum Terrane, and it seems plausible that this TLP activity may be tied to residual outgassing from the formerly largest volcanic ffusion sites from the deep lunar interior. With the coming in the next few years of robotic spacecraft followed by human exploration, the study of TLPs and outgassing is both promising and imperiled. We will have an unprecedented pportunity to study lunar outgassing, but will also deal with a greater burden of anthropogenic lunar gas than ever produced. There is a pressing need to study lunar atmosphere and its sources while still pristine. [Abstract abridged.]Comment: 35 pages, 3 figures, submitted to Icarus. Other papers in series found at http://www.astro.columbia.edu/~arlin/TLP