Ecosystem Conditions That Influence the Viability of an Old-Forest Species with Limited Vagility: The Red Tree Vole.

We evaluated ecosystem conditions known to influence the viability of a strictly arboreal species (the red tree vole, ) endemic and historically distributed in the forests across the Coast Range, Cascades, and Klamath Mountains ecoregions in the Western United States of America. We found widespread reductions in ecosystem conditions needed to support the long-term viability of the red tree vole. This was particularly evident in the Coast Range where the weighted watershed index (WWI) was 26% of its historical value, and the current probability of maintaining viability departed the most from historical viability probabilities in ecoregions that were evaluated.

Navigating fragmented landscapes: Canada lynx brave poor quality habitats while traveling.

Anthropogenic and natural habitat fragmentation inhibit movement of animals through landscapes. An important challenge for connectivity conservation is determining which conditions facilitate or limit movements, so that these areas can be prioritized for protection or restoration. We examine Canada lynx Lynx canadensis habitat connectivity in the fragmented North Cascade Mountains of Washington, as an example of a highly mobile species that is specialized both on prey and in habitat needs.

Correction: Mek1 Down Regulates Rad51 Activity during Yeast Meiosis by Phosphorylation of Hed1.

[This corrects the article DOI: 10.1371/journal.pgen.

Spider silk-like proteins derived from transgenic Nicotiana tabacum.

The high tensile strength and biocompatibility of spider dragline silk makes it a desirable material in many engineering and tissue regeneration applications. Here, we present the feasibility to produce recombinant proteins in transgenic tobacco Nicotiana tabacum with sequences representing spider silk protein building blocks . Recombinant mini-spidroins contain native N- and C-terminal domains of major ampullate spidroin 1 (rMaSp1) or rMaSp2 flanking an abbreviated number (8, 16 or 32) of consensus repeat domains.

DNA RECOMBINATION. Base triplet stepping by the Rad51/RecA family of recombinases.

DNA strand exchange plays a central role in genetic recombination across all kingdoms of life, but the physical basis for these reactions remains poorly defined. Using single-molecule imaging, we found that bacterial RecA and eukaryotic Rad51 and Dmc1 all stabilize strand exchange intermediates in precise three-nucleotide steps. Each step coincides with an energetic signature (0.

Promotion of presynaptic filament assembly by the ensemble of S. cerevisiae Rad51 paralogues with Rad52.

The conserved budding yeast Rad51 paralogues, including Rad55, Rad57, Csm2 and Psy3 are indispensable for homologous recombination (HR)-mediated chromosome damage repair. Rad55 and Rad57 are associated in a heterodimer, while Csm2 and Psy3 form the Shu complex with Shu1 and Shu2. Here we show that Rad55 bridges an interaction between Csm2 with Rad51 and Rad52 and, using a fully reconstituted system, demonstrate that the Shu complex synergizes with Rad55-Rad57 and Rad52 to promote nucleation of Rad51 on single-stranded DNA pre-occupied by replication protein A (RPA).

DNA sequence alignment by microhomology sampling during homologous recombination.

Homologous recombination (HR) mediates the exchange of genetic information between sister or homologous chromatids. During HR, members of the RecA/Rad51 family of recombinases must somehow search through vast quantities of DNA sequence to align and pair single-strand DNA (ssDNA) with a homologous double-strand DNA (dsDNA) template. Here, we use single-molecule imaging to visualize Rad51 as it aligns and pairs homologous DNA sequences in real time.

Regulation of DNA pairing in homologous recombination.

Homologous recombination (HR) is a major mechanism for eliminating DNA double-strand breaks from chromosomes. In this process, the break termini are resected nucleolytically to form 3' ssDNA (single-strand DNA) overhangs. A recombinase (i.

Down-regulation of Rad51 activity during meiosis in yeast prevents competition with Dmc1 for repair of double-strand breaks.

Interhomolog recombination plays a critical role in promoting proper meiotic chromosome segregation but a mechanistic understanding of this process is far from complete. In vegetative cells, Rad51 is a highly conserved recombinase that exhibits a preference for repairing double strand breaks (DSBs) using sister chromatids, in contrast to the conserved, meiosis-specific recombinase, Dmc1, which preferentially repairs programmed DSBs using homologs. Despite the different preferences for repair templates, both Rad51 and Dmc1 are required for interhomolog recombination during meiosis.

Occupational risk factors and back injury.

Twenty-one risk factors affecting laborers in manual materials handling tasks were analyzed to determine what, if any, statistically significant relationships existed between the factors and the emergence of occupational back injury. The statistically significant risk factors (p ≤ .05) in the univariate analysis were determined to be weight lifted per hour (work intensity), trunk twists per hour, weight lifted per day, frequency of lift, trunk motions per hour, and trunk flexions per hour, with odds ratios (ORs) of 1.

Functional attributes of the Saccharomyces cerevisiae meiotic recombinase Dmc1.

The role of Dmc1 as a meiosis-specific general recombinase was first demonstrated in Saccharomyces cerevisiae. Progress in understanding the biochemical mechanism of ScDmc1 has been hampered by its tendency to form inactive aggregates. We have found that the inclusion of ATP during protein purification prevents Dmc1 aggregation.

Recombinant Dragline Silk-Like Proteins-Expression and Purification.

Spider dragline silk is a proteinaceous fiber with impressive physical characteristics making it attractive for use in advanced materials. The fiber is composed of two proteins (spidroins MaSp1 and MaSp2), each of which contains a large central repeat array flanked by non-repetitive N- and C-terminal domains. The repeat arrays appear to be largely responsible for the tensile properties of the fiber, suggesting that the N- and C-terminal domains may be involved in self-assembly.

NMR assignments of the N-terminal domain of Nephila clavipes spidroin 1.

The building blocks of spider dragline silk are two fibrous proteins secreted from the major ampullate gland named spidroins 1 and 2 (MaSp1, MaSp2). These proteins consist of a large central domain composed of approximately 100 tandem copies of a 35-40 amino acid repeat sequence. Non-repetitive N and C-terminal domains, of which the C-terminal domain has been implicated to transition from soluble and insoluble states during spinning, flank the repetitive core.

Spidroin N-terminal domain promotes a pH-dependent association of silk proteins during self-assembly.

Spider silks are spun from concentrated solutions of spidroin proteins. The appropriate timing of spidroin assembly into organized fibers must be highly regulated to avoid premature fiber formation. Chemical and physical signals presented to the silk proteins as they pass from the ampulle and through the tapered duct include changes in ionic environment and pH as well as the introduction of shear forces.

Personal and non-occupational risk factors and occupational injury/illness.

Background: The materials handling industry performs is an essential function in the world economy, however, it is plagued with occupationally related injuries and illnesses. Understanding the risk factors may assist this industry in alleviating these injuries and illnesses, as well as their associated costs.

Methods: Forty-eight personal and non-occupational risk factors were measured and evaluated for statistically significant relationships with occupational injury in 442 volunteer manual material handlers who worked for three different companies, at nine US locations, with 15 different job descriptions.

A prospective field study of the relationship of potential occupational risk factors with occupational injury/illness.

Twenty-one occupationally related risk factors were measured and prospectively evaluated for statistically significant relationships with occupational injury/illness in 442 manual material handlers, working for three different companies, at nine U.S. locations, and encompassing 15 different job descriptions.