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111.
Modeling the Ecological and Phenological Predictors of Fruit Consumption by Gibbons (Hylobates albibarbis)
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Christopher Dillis Lydia Beaudrot Katie L. Feilen Dena J. Clink Heiko U. Wittmer Andrew J. Marshall 《Biotropica》2015,47(1):85-93
Understanding the ecological interactions between plant reproductive strategies and frugivore feeding behavior can offer insight into the maintenance of tropical forest biodiversity. We examined the role of plant ecological and phenological characteristics in influencing fruit consumption by the White‐bearded gibbon (Hylobates albibarbis) in Gunung Palung National Park, Indonesian Borneo. Gibbons are widespread across Borneo, highly frugivorous and perform important seed dispersal services. We compare multiple models using information criteria to identify the ecological and phenological predictors that most strongly influence gibbon fruit use of 154 plant genera. The most important predictors of resource use were the overall abundance of a genus and the consistency of fruit availability. Plant genera can maintain constant fruit availability as a result of (1) individual stems fruiting often or (2) stems fruiting out of synchrony with each other (asynchrony). Our results demonstrate that gibbons prefer to feed on plant genera that provide consistent fruit availability due to fruiting asynchrony. Because gibbons feed more often on genera that fruit asynchronously, gibbons are more likely to disperse seeds of plant genera with this reproductive strategy. Research on other frugivorous species is needed to determine whether the results for gibbons are generalizable more broadly. Finally, these results suggest that asynchronously fruiting plant genera may be particularly important for habitat restoration in tropical forests designed for frugivore conservation. 相似文献
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Jingxin Chen Evan C. Ray Megan E. Yates Teresa M. Buck Jeffrey L. Brodsky Carol L. Kinlough Katie L. Winarski Rebecca P. Hughey Thomas R. Kleyman Shaohu Sheng 《The Journal of biological chemistry》2015,290(41):25140-25150
The extracellular regions of epithelial Na+ channel subunits are highly ordered structures composed of domains formed by α helices and β strands. Deletion of the peripheral knuckle domain of the α subunit in the αβγ trimer results in channel activation, reflecting an increase in channel open probability due to a loss of the inhibitory effect of external Na+ (Na+ self-inhibition). In contrast, deletion of either the β or γ subunit knuckle domain within the αβγ trimer dramatically reduces epithelial Na+ channel function and surface expression, and impairs subunit maturation. We systematically mutated individual α subunit knuckle domain residues and assessed functional properties of these mutants. Cysteine substitutions at 14 of 28 residues significantly suppressed Na+ self-inhibition. The side chains of a cluster of these residues are non-polar and are predicted to be directed toward the palm domain, whereas a group of polar residues are predicted to orient their side chains toward the space between the knuckle and finger domains. Among the mutants causing the greatest suppression of Na+ self-inhibition were αP521C, αI529C, and αS534C. The introduction of Cys residues at homologous sites within either the β or γ subunit knuckle domain resulted in little or no change in Na+ self-inhibition. Our results suggest that multiple residues in the α subunit knuckle domain contribute to the mechanism of Na+ self-inhibition by interacting with palm and finger domain residues via two separate and chemically distinct motifs. 相似文献
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The essential cellular functions of secretion and protein degradation require a molecular machine to unfold and translocate proteins either across a membrane or into a proteolytic complex. Protein translocation is also critical for microbial pathogenesis, namely bacteria can use translocase channels to deliver toxic proteins into a target cell. Anthrax toxin (Atx), a key virulence factor secreted by Bacillus anthracis, provides a robust biophysical model to characterize transmembrane protein translocation. Atx is comprised of three proteins: the translocase component, protective antigen (PA) and two enzyme components, lethal factor (LF) and oedema factor (OF). Atx forms an active holotoxin complex containing a ring-shaped PA oligomer bound to multiple copies of LF and OF. These complexes are endocytosed into mammalian host cells, where PA forms a protein-conducting translocase channel. The proton motive force unfolds and translocates LF and OF through the channel. Recent structure and function studies have shown that LF unfolds during translocation in a force-dependent manner via a series of metastable intermediates. Polypeptide-binding clamps located throughout the PA channel catalyse substrate unfolding and translocation by stabilizing unfolding intermediates through the formation of a series of interactions with various chemical groups and α-helical structure presented by the unfolding polypeptide during translocation. 相似文献
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Tran TD Pryde DC Jones P Adam FM Benson N Bish G Calo F Ciaramella G Dixon R Duckworth J Fox DN Hay DA Hitchin J Horscroft N Howard M Gardner I Jones HM Laxton C Parkinson T Parsons G Proctor K Smith MC Smith N Thomas A 《Bioorganic & medicinal chemistry letters》2011,21(8):2389-2393
The synthesis and structure-activity relationships of a series of novel interferon inducers are described. Pharmacokinetic studies and efficacy assessment of a series of 8-oxo-3-deazapurine analogues led to the identification of compound 33, a potent and selective agonist of the TLR7 receptor with an excellent in vivo efficacy profile in a mouse model. 相似文献