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Cochlear outer hair cells undergo reversible changes in shape when externally stimulated. This response, known as OHC motility, is a central component of the cochlear amplifier, the mechanism responsible for the high sensitivity of mammalian hearing. We report that actin depolymerization, as regulated by activation/inhibition of LIMK/cofilin-mediated pathways, has a pivotal role in OHC motility. LIMK-mediated cofilin phosphorylation, which inhibits the actin depolymerizing activity of this protein, increases both electromotile amplitude and total length of guinea pig OHCs. In contrast, a decrease in cofilin phosphorylation reduces both OHC electromotile amplitude and OHC length. Experiments with acetylcholine and lysophosphatidic acid indicate that the effects of these agents on OHC motility are associated with regulation of cofilin phosphorylation via different signaling cascades. On the other hand, nonlinear capacitance measurements confirmed that all observed changes in OHC motile response were independent of the performance of the motor protein prestin. Altogether, these results strongly support the hypothesis that the cytoskeleton has a major role in the regulation of OHC motility, and identify actin depolymerization as a key process for modulating cochlear amplification. 相似文献
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Anastasiya ANTONEVICH Sergey NAIDENKO 《动物学报》2008,54(1):12-19
研究了非自由生活的4窝11只猞猁幼仔的玩耍行为、亲和及入侵关系的变化.观察到36-57日龄幼仔的同胞打斗行为,这些打斗减少了这些幼仔之间游戏性接触的频次.这个"打斗期"与游戏行为和食性的变化同步发生.打斗后,幼仔游戏性接触的非对称性以及同胞之间的偏爱更加清楚.这些打斗导致了不同窝的幼仔之间等级结构的建立. 相似文献
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Background
The available data demonstrate that even in universal metabolic pathways, some species-specific regulatory features of structural genes are present. For instance, in the anthocyanin biosynthesis pathway (ABP), genes may be regulated by ABP-specific regulatory factors, and their expression levels may be strongly associated with anthocyanin pigmentation, or they may be expressed independently of pigmentation. A dataset of orthologous ABP genes (Chs, Chi, F3h, F3’h, Dfr, Ans) from monocot and dicot plant species that have distinct gene regulation patterns and different types of pollination was constructed to test whether these factors affect the evolution of the genes.Results
Using a maximum likelihood approach, we demonstrated that although the whole set of the ABP genes is under purifying selection, with greater selection acting on the upstream genes than on the downstream genes, genes from distinct groups of plant species experienced different strengths of selective pressure. The selective pressure on the genes was higher in dicots than in monocots (F3h and further downstream genes) and in pollinator-dependent plants than in pollinator-independent species (Chi and further downstream genes), suggesting an important role of pollination type in the evolution of the anthocyanin biosynthesis gene network. Contrasting effects of the regulation patterns on evolution were detected for the F3h and Dfr genes, with greater selective pressure on the F3h gene in plant species where the gene expression was not strongly associated with pigmentation and greater selective pressure on Dfr in plant species where the gene expression was associated with pigmentation.Conclusions
We demonstrated the effects of pollination type and patterns of regulation on the evolution of the ABP genes, but the evolution of some of the genes could not be explained in the framework of these factors, such as the weaker selective pressure acting on Chs in species that attract pollinators or the stronger selective pressure on F3h in plant species where the gene expression was not associated with pigmentation. The observations suggest that additional factors could affect the evolution of these genes. One such factor could be an effect of gene duplication with further division of functions among gene copies and relaxed selective pressure acting on them. Additional tests with an appropriate dataset combining data on duplicated gene sequences and their functions in the flavonoid biosynthesis pathway are required to test this hypothesis.85.
Alex V. Kochetov Anastasiya Y. Glagoleva Kseniya V. Strygina Elena K. Khlestkina Sophia V. Gerasimova Salmaz M. Ibragimova Natalja V. Shatskaya Gennady V. Vasilyev Dmitry A. Afonnikov Nikolay A. Shmakov Olga Y. Antonova Tatyana A. Gavrilenko Natalia V. Alpatyeva Alexander Khiutti Olga S. Afanasenko 《BMC plant biology》2017,17(2):251
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Antibodies against H3 and H4 histones from the sera of HIV‐infected patients catalyze site‐specific degradation of these histones 下载免费PDF全文
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Alexander V. Tyakht Alexander I. Manolov Alexandra V. Kanygina Dmitry S. Ischenko Boris A. Kovarsky Anna S. Popenko Alexander V. Pavlenko Anna V. Elizarova Daria V. Rakitina Julia P. Baikova Valentina G. Ladygina Elena S. Kostryukova Irina Y. Karpova Tatyana A. Semashko Andrei K. Larin Tatyana V. Grigoryeva Mariya N. Sinyagina Sergei Y. Malanin Petr L. Shcherbakov Anastasiya Y. Kharitonova Igor L. Khalif Marina V. Shapina Igor V. Maev Dmitriy N. Andreev Elena A. Belousova Yulia M. Buzunova Dmitry G. Alexeev Vadim M. Govorun 《BMC genomics》2018,19(1):968
Background
Crohn’s disease is associated with gut dysbiosis. Independent studies have shown an increase in the abundance of certain bacterial species, particularly Escherichia coli with the adherent-invasive pathotype, in the gut. The role of these species in this disease needs to be elucidated.Methods
We performed a metagenomic study investigating the gut microbiota of patients with Crohn’s disease. A metagenomic reconstruction of the consensus genome content of the species was used to assess the genetic variability.Results
The abnormal shifts in the microbial community structures in Crohn’s disease were heterogeneous among the patients. The metagenomic data suggested the existence of multiple E. coli strains within individual patients. We discovered that the genetic diversity of the species was high and that only a few samples manifested similarity to the adherent-invasive varieties. The other species demonstrated genetic diversity comparable to that observed in the healthy subjects. Our results were supported by a comparison of the sequenced genomes of isolates from the same microbiota samples and a meta-analysis of published gut metagenomes.Conclusions
The genomic diversity of Crohn’s disease-associated E. coli within and among the patients paves the way towards an understanding of the microbial mechanisms underlying the onset and progression of the Crohn’s disease and the development of new strategies for the prevention and treatment of this disease.88.
Sevostyanova A Feklistov A Barinova N Heyduk E Bass I Klimasauskas S Heyduk T Kulbachinskiy A 《The Journal of biological chemistry》2007,282(30):22033-22039
Bacterial RNA polymerase holoenzyme relies on its sigma subunit for promoter recognition and opening. In the holoenzyme, regions 2 and 4 of the sigma subunit are positioned at an optimal distance to allow specific recognition of the -10 and -35 promoter elements, respectively. In free sigma, the promoter binding regions are positioned closer to each other and are masked for interactions with the promoter, with sigma region 1 playing a role in the masking. To analyze the DNA-binding properties of the free sigma, we selected single-stranded DNA aptamers that are specific to primary sigma subunits from several bacterial species, including Escherichia coli and Thermus aquaticus. The aptamers share a consensus motif, TGTAGAAT, that is similar to the extended -10 promoter. We demonstrate that recognition of this motif by sigma region 2 occurs without major structural rearrangements of sigma observed upon the holoenzyme formation and is not inhibited by sigma regions 1 and 4. Thus, the complex process of the -10 element recognition by RNA polymerase holoenzyme can be reduced to a simple system consisting of an isolated sigma subunit and a short aptamer oligonucleotide. 相似文献
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de Figueiredo P Terra B Anand JK Hikita T Sadilek M Monks DE Lenskiy A Hakomori S Nester EW 《Extremophiles : life under extreme conditions》2007,11(1):133-143
Penicillins are widespread in nature and lethal to growing bacteria. Because of the severe threat posed by these antibiotics,
bacteria have evolved a wide variety of strategies for combating them. Here, we describe one unusual strategy that involves
the activity of a catalytic carbohydrate. We show that the cyclic oligosaccharide, β-cyclodextrin (βCD), can hydrolyze, and
thereby inactivate, penicillin in vivo. Moreover, we demonstrate that this catalytic activity contributes to the antibiotic
resistance of a bacterium that synthesizes this oligosaccharide in the laboratory. Taken together, these data not only expand
our understanding of the biochemistry of penicillin resistance, but also provide the first demonstration of natural carbohydrate-mediated
catalysis in a living system.
Paul de Figueiredo, Becky Terra and Jasbir Kaur Anand have contributed equally to this work. 相似文献
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