Transformations at high latitudes:Why do red knots bring body stores to the breeding grounds?

We examined changes in body composition of Red Knots (Calidris canutus islandica) following arrival on their High Arctic breeding grounds at Alert, Ellesmere Island, Canada. Knots arrived in late May and early June with large fat and muscle stores. In the next two weeks, fat and protein stores (pectoral muscles) declined, while increases occurred in gizzard, proventriculus, gut length, heart, liver, and possibly gonads. Most stores were used before egg laying occurred and were therefore not available for egg formation. Early development of ova in some females suggests that body stores may be incorporated into the earliest eggs. While stores may be used for survival when conditions are difficult after arrival, their rapid loss and the concomitant increase in other organs suggests that a major function may be to facilitate a transformation from a physiological state suitable for mi gration to one suitable, and possibly required, for successful breeding

Development of the text of the Ramsar Convention: 1965–1971

The ‘Ramsar’ Convention on Wetlands was the first of the modern era global biodiversity conventions and remains the only multilateral environmental agreement focused on a single group of ecosystem types. At the time of initial discussions within the wetland conservation science community in the late 1960s, its ambition was unprecedented, with no successful models to draw upon, especially with regard to novel concepts such as the modus for an ‘internationally protected site’. Drawing on previously unpublished draft texts, we track the Convention’s textual development to its ultimate agreement in 1971. During this period its geographic scope changed from an initial European to global focus, whereas core obligations related to the designation of internationally important wetlands and the provision of secretariat coordination functions were substantively developed. We present (as supplementary material) all draft texts, from 1965 to 1971, previously unavailable online

Organocatalytic sulfoxidation

Treatment of a sulfide with a catalytic amount of a 1,3 diketone in the presence of silica sulfuric acid as a co-catalyst and hydrogen peroxide (50% aq) as the stoichiometric oxidant leads to the corresponding sulfoxide product. The reaction is effective for diaryl, aryl-alkyl and dialkyl sulfides and is tolerant of oxidisable and acid sensitive functional groups. Investigations have shown that the tris-peroxide 2, formed on reaction of pentane-2,4-dione with hydrogen peroxide under acidic reaction conditions, can oxidise two equivalents of sulfide using the exocyclic peroxide groups whereas the endocyclic peroxide remains intact. Calculations provide a mechanism consistent with experimental observations and suggest the reaction proceeds via an initial acid catalysed ring opening of a protonated tris-peroxide prior to oxygen transfer to a sulfur nucleophile

Inhibition of the ULK1 protein complex suppresses Staphylococcus-induced autophagy and cell death

Autophagy plays multiple roles in host cells challenged with extracellular pathogens. Here, we aimed to explore whether autophagy inhibition could prevent bacterial infections. We first confirmed widely distinct patterns of autophagy responses in host cells infected with Staphylococcus aureus, as compared with Salmonella. Only infection with Staphylococcus produced strong accumulation of lipidated autophagy-related protein LC3B (LC3B-II). Infection with virulent Staphylococcus strains induced formation of p62-positive aggregates, suggestive of accumulated ubiquitinated targets. During Salmonella infection, bacteria remain enclosed by lysosomal-associated membrane protein 2 (LAMP2)-positive lysosomes, whereas virulent Staphylococcus apparently exited from enlarged lysosomes and invaded the cytoplasm. Surprisingly, Staphylococcus appeared to escape from the lysosome without generation of membrane-damage signals as detected by Galectin3 recruitment. In contrast, Salmonella infection produced high levels of lysosomal damage, consistent with a downstream antibacterial xenophagy response. Lastly, we studied the Unc-51-like autophagy-activating kinase 1 (ULK1) regulatory complex, including the essential subunit autophagy-related protein 13 (ATG13). Infection of cells with either Staphylococcus or Salmonella led to recruitment of ATG13 to sites of cytosolic bacterial cells to promote autophagosome formation. Of note, genetic targeting of ATG13 suppressed autophagy and the ability of Staphylococcus to infect and kill host cells. Two different ULK1 inhibitors also prevented Staphylococcus intracellular replication and host cell death. Interestingly, inhibition of the ULK1 pathway had the opposite effect on Salmonella, sensitizing cells to the infection. Our results suggest that ULK1 inhibitors may offer a potential strategy to impede cellular infection by Staphylococcus aureus

Cell Surface Remodeling of Mycobacterium abscessus under Cystic Fibrosis Airway Growth Conditions.

Understanding the physiological processes underlying the ability of Mycobacterium abscessus to become a chronic pathogen of the cystic fibrosis (CF) lung is important to the development of prophylactic and therapeutic strategies to better control and treat pulmonary infections caused by these bacteria. Gene expression profiling of a diversity of M. abscessus complex isolates points to amino acids being significant sources of carbon and energy for M. abscessus in both CF sputum and synthetic CF medium and to the bacterium undergoing an important metabolic reprogramming in order to adapt to this particular nutritional environment. Cell envelope analyses conducted on the same representative isolates further revealed unexpected structural alterations in major cell surface glycolipids known as the glycopeptidolipids (GPLs). Besides showing an increase in triglycosylated forms of these lipids, CF sputum- and synthetic CF medium-grown isolates presented as yet unknown forms of GPLs representing as much as 10% to 20% of the total GPL content of the cells, in which the classical amino alcohol located at the carboxy terminal of the peptide, alaninol, is replaced with the branched-chain amino alcohol leucinol. Importantly, both these lipid changes were exacerbated by the presence of mucin in the culture medium. Collectively, our results reveal potential new drug targets against M. abscessus in the CF airway and point to mucin as an important host signal modulating the cell surface composition of this pathogen

How to Build Transcriptional Network Models of Mammalian Pattern Formation

Genetic regulatory networks of sequence specific transcription factors underlie pattern formation in multicellular organisms. Deciphering and representing the mammalian networks is a central problem in development, neurobiology, and regenerative medicine. Transcriptional networks specify intermingled embryonic cell populations during pattern formation in the vertebrate neural tube. Each embryonic population gives rise to a distinct type of adult neuron. The homeodomain transcription factor Lbx1 is expressed in five such populations and loss of Lbx1 leads to distinct respecifications in each of the five populations. allele, respectively. Microarrays were used to show that expression levels of 8% of all transcription factor genes were altered in the respecified pool. These transcription factor genes constitute 20–30% of the active nodes of the transcriptional network that governs neural tube patterning. Half of the 141 regulated nodes were located in the top 150 clusters of ultraconserved non-coding regions. Generally, Lbx1 repressed genes that have expression patterns outside of the Lbx1-expressing domain and activated genes that have expression patterns inside the Lbx1-expressing domain.nalysis, and think that it will be generally useful in discovering and assigning network interactions to specific populations. We discuss how ANCEA, coupled with population partitioning analysis, can greatly facilitate the systematic dissection of transcriptional networks that underlie mammalian patterning

Rapid circulation of warm subtropical waters in a major glacial fjord in East Greenland

Author Posting. © The Authors, 2009. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature Geoscience 3 (2010): 182-186, doi:10.1038/ngeo764.The recent rapid increase in mass loss from the Greenland Ice Sheet is primarily attributed to an acceleration of outlet glaciers. One possible cause is increased melting at the ice/ocean interface driven by the synchronous warming of subtropical waters offshore of Greenland. This hypothesis is largely untested, however, because of the lack of observations from Greenland’s glacial fjords and our limited understanding of their dynamics. Here, we present new ship-based and moored oceanographic data, collected in Sermilik Fjord, a large glacial fjord in East Greenland, showing that subtropical waters are present throughout the fjord and are continuously replenished via a wind-driven exchange with the shelf, where they occur year-round. The temperature and rapid renewal of these waters suggest that, at present, they drive enhanced submarine melting at the terminus. Key controls on the melting rate are the volume and properties of subtropical waters on the shelf and the patterns of the along-shore winds, suggesting the glaciers’ acceleration was triggered by a combination of atmospheric and oceanic changes. These measurements provide evidence of rapid advective pathway for the transmission of oceanic variability to the ice-sheet margins and highlight an important process that is missing from prognostic ice-sheet models.F.S. acknowledges support from WHOI’s Ocean and Climate Change Institute’s Arctic Research Initiative and from NSF OCE 0751896, and G.S.H and L.A.S from NASA’s Cryospheric Sciences Program. Funding for the hooded seal deployments was obtained from the International Governance and Atlantic Seal Research Program, Fisheries and Oceans, Canada, to G. B. S. and to the Greenland Institute of Natural Resources to A. R. A