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91.
92.
Forecasting potential routes for movement of endemic birds among important sites for biodiversity in the Albertine Rift under projected climate change
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Robert Bagchi David G. Hole Stuart H. M. Butchart Yvonne C. Collingham Lincoln D. Fishpool Andrew J. Plumptre Isaiah Owiunji Hamlet Mugabe Stephen G. Willis 《Ecography》2018,41(2):401-413
The ability of species to shift their distributions in response to climate change may be impeded by lack of suitable climate or habitat between species’ current and future ranges. We examined the potential for climate and forest cover to limit the movement of bird species among sites of biodiversity importance in the Albertine Rift, East Africa, a biodiversity hotspot. We forecasted future distributions of suitable climate for 12 Albertine Rift endemic bird species using species distribution models based on current climate data and projections of future climate. We used these forecasts alongside contemporary forest cover and natal dispersal estimates to project potential movement of species over time. We identified potentially important pathways for the bird species to move among 30 important bird and biodiversity areas (IBAs) that are both currently forested and projected to provide suitable climate over intervening time periods. We examined the relative constraints imposed by availability of suitable climate and forest cover on future movements. The analyses highlighted important pathways of potential dispersal lying along a north‐south axis through high elevation areas of the Albertine Rift. Both forest availability and climate suitability were projected to influence bird movement through these landscapes as they are affected by future climate change. Importantly, forest cover and areas projected to contain suitable climate in future were often dissociated in space, which could limit species’ responses to climate change. A lack of climatically suitable areas was a far greater impediment to projected movement among IBAs than insufficient forest cover. Although current forest cover appears sufficient to facilitate movement of bird species in this region, protecting the remaining forests in areas also projected to be climatically suitable for species to move through in the future should be a priority for adaptation management. 相似文献
93.
Isaiah A. Awogun 《Biotechnic & histochemistry》1978,53(4):187-189
A rapid whole mount staining method is described to identify and differentiate microfilariae without elaborate processing. A single solution combining Hoyer's mounting medium and hematoxylin stain facilitates light microscopic examination of nuclei and sheaths of microfilariae. The new technique stains microfilariae adequately in three to seven minutes at 60-64 C making the method preferable to conventional methods that may take as long as 45 to 60 minutes. Lantern heat may be used to heat slides in rural areas with good results. 相似文献
94.
The Sec2 translocase of the chloroplast inner envelope contains a unique and dedicated SECE2 component
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Yubing Li Rajneesh Singhal Isaiah W. Taylor Patrick H. McMinn Xien Yu Chua Kenneth Cline Donna E. Fernandez 《The Plant journal : for cell and molecular biology》2015,84(4):647-658
Biogenesis of chloroplasts involves a series of protein trafficking events. Nuclear‐encoded proteins are imported into the organelle, and then trafficked to various chloroplast locations by systems that are directly homologous to bacterial systems. Although the thylakoid‐based systems have been studied extensively, much less is known about the systems that reside and function in the inner envelope membrane. One such system, the Sec2 system, is homologous to both the thylakoid‐based Sec1 system and bacterial Sec systems, and may mediate both integration and translocation across the inner envelope. At a minimum, this system is expected to include three components, but only two, SCY2 and SECA2, have been identified in Arabidopsis. Bioinformatics and protein modeling were used to identify the protein encoded by At4g38490 as a candidate for the missing component (SECE2). Cellular localization, biochemistry, protein interaction assays in yeast, and co‐immunoprecipitation experiments were used to establish that this protein is an integral membrane protein of the inner envelope, and specifically interacts with the SCY2 component in vivo. Sequence analyses indicated that SECE2 proteins are found in a variety of plants, and differ from the thylakoid SECE1 proteins in a stroma‐exposed helical domain, which may contribute to their specificity. Finally, a genetic analysis indicated that SECE2 plays an essential role in plant growth and development. 相似文献
95.
Timothy J. Stevens Isaiah T. Arkin 《Protein science : a publication of the Protein Society》2001,10(12):2507-2517
It has been shown previously that some membrane proteins have a conserved core of amino acid residues. This idea not only serves to orient helices during model building exercises but may also provide insight into the structural role of residues mediating helix-helix interactions. Using experimentally determined high-resolution structures of alpha-helical transmembrane proteins we show that, of the residues within the hydrophobic transmembrane spans, the residues at lipid and subunit interfaces are more evolutionarily variable than those within the lipid-inaccessible core of a polypeptide's transmembrane domain. This supports the idea that helix-helix interactions within the same polypeptide chain and those at the interface between different polypeptide chains may arise in distinct ways. To show this, we use a new method to estimate the substitution rate of an amino acid residue given an alignment and phylogenetic tree of closely related proteins. This method gives better sensitivity in the otherwise-conserved transmembrane domains than a conventional similarity analysis and is relatively insensitive to the sequences used. 相似文献
96.
97.
Dieter Langosch Isaiah T. Arkin 《Protein science : a publication of the Protein Society》2009,18(7):1343-1358
Within 1 or 2 decades, the reputation of membrane‐spanning α‐helices has changed dramatically. Once mostly regarded as dull membrane anchors, transmembrane domains are now recognized as major instigators of protein–protein interaction. These interactions may be of exquisite specificity in mediating assembly of stable membrane protein complexes from cognate subunits. Further, they can be reversible and regulatable by external factors to allow for dynamic changes of protein conformation in biological function. Finally, these helices are increasingly regarded as dynamic domains. These domains can move relative to each other in different functional protein conformations. In addition, small‐scale backbone fluctuations may affect their function and their impact on surrounding lipid shells. Elucidating the ways by which these intricate structural features are encoded by the amino acid sequences will be a fascinating subject of research for years to come. 相似文献
98.
The helix tilt and rotational orientation of the transmembrane segment of M2, a 97-residue protein from the Influenza A virus that forms H(+)-selective ion channels, have been determined by attenuated total reflection site-specific infrared dichroism using a novel labeling approach. Triple C-deuteration of the methyl group of alanine in the transmembrane domain of M2 was used, as such modification shifts the asymmetric and symmetric stretching vibrations of the methyl group to a transparent region of the infrared spectrum. Structural information can then be obtained from the dichroic ratios corresponding to these two vibrations. Two consecutive alanine residues were labeled to enhance signal intensity. The results obtained herein are entirely consistent with previous site-specific infrared dichroism and solid-state nuclear magnetic resonance experiments, validating C-deuterated alanine as an infrared structural probe that can be used in membrane proteins. This new label adds to the previously reported (13)C [double bond] (18)O and C-deuterated glycine as a tool to analyze the structure of simple transmembrane segments and will also increase the feasibility of the study of polytopic membrane proteins with site-specific infrared dichroism. 相似文献
99.
Lu P Hankel IL Hostager BS Swartzendruber JA Friedman AD Brenton JL Rothman PB Colgan JD 《The Journal of biological chemistry》2011,286(20):18311-18319
100.