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排序方式: 共有467条查询结果,搜索用时 15 毫秒
1.
Wetland ecosystems are the natural centers of freshwater formation in northern Russia lowland landscapes. The humic acidic waters formed in bogs feed the numerous lakes of the northern regions. One milliliter of the water in these lakes contains up to 104 ultrasmall microbial cells that pass through “bacterial” filters with a pore size of 0.22 μm. The vast majority of these cells do not grow on nutrient media and cannot be identified by routine cultivation-based approaches. Their identification was performed by analysis of clone libraries obtained by PCR amplification of archaeal and bacterial 16S rRNA genes from the fraction of cells collected from water filtrates of acidic lakes. Most of the obtained bacterial 16S rRNA gene sequences represented the class Betaproteobacteria and exhibited the highest homology of (94–99%) with 16S rRNA genes of representatives of the genera Herbaspirillum, Herminiimonas, Curvibacter, and Burkholderia. The archaeal 16S rRNA gene clone library comprised genes of Euryarchaeota representatives. One-third of these genes exhibited 97–99% homology to the 16S rRNA genes of taxonomically described organisms of the orders Methanobacteriales and Methanosarcinales. The rest of the cloned archaeal 16S rRNA genes were only distantly related (71–74% homology) to those in all earlier characterized archaea. 相似文献
2.
3.
Iu B Lishmanov T V Fedotova M I Titov 《Biulleten' eksperimental'no? biologii i meditsiny》1989,107(6):704-706
The protective action of enzymatically stable analogue of Leu-enkephalin (D-ala-2-leu5-arg6), injected intraperitoneally, in the course of stress- and epinephrine induced myocardial damage was demonstrated in animal (129 white rats) experiments. Two effect of enkephalin were sufficient for the cardiac protection: enkephalin-stimulated prostacyclin biosynthesis and simultaneous inhibition of thromboxane production. 相似文献
4.
This study was pursued on hybrid (CBA X C57Bl)F1 mice at the ages of 17 and 27 months irradiated at a dose of 4 Gy. It was shown that the postirradiation recovery of haemopoiesis in old mice was the same as in the young (2-3 month-old), and in some respects (for instance, granulocytic and erythroid cells of the bone marrow, and CFUc) the recovery was even more active exhibiting a period of a pronounced hyperregeneration. 相似文献
5.
P D Gorizontov M I Fedotova O I Belousova R M Khaitov L I Chermeneva 《Biulleten' eksperimental'no? biologii i meditsiny》1980,89(4):415-417
Cellular composition of the bone marrow, spleen and peripheral blood was studied after 6-hour immobilization on the back in experiments on 4 groups of (CBAxC57BL)F1 mice with varying degree of T lymphocyte deficiency (thymectomy, sham thymectomy, administration of antilymphocytic serum, B mice). The evidence obtained shows that the "lymphoid peak" recorded in the bone marrow during stress is likely to be formed at the expense of T and B lymphocyte migration from the peripheral lymphoid organs. The data have been also obtained, indicating that T lymphocytes migrating to the bone marrow during the first 6-9 hours after the exposure to stress may participate in granulocytopoiesis activation. 相似文献
6.
Elena Iurova Evgenii Beloborodov Elizaveta Tazintseva Aleksandr Fomin Alexander Shutov Sergei Slesarev Yana Saenko Yury Saenko 《Journal of peptide science》2021,27(1)
Peptide toxins of arthropods are one of the potential sources of bioactive substances. Toxins are able to bind to calcium channels and block them. Ca2+ ions play an important role in many cell processes, in particular, in apoptosis. In this work, we study the effect of some arthropod toxins on intracellular processes associated with the induction of apoptosis. Synthetic analogs of U5‐scytotoxin‐Sth1a, ω‐hexatoxin‐Hv1a, ω‐theraphotoxin‐Hhn2a, and μ‐agatoxin‐Aa1a toxins—inhibitors of calcium L, P, and Q channels and sodium channels were used in the study. Apoptosis was induced by AC‐1001 H3 peptide. We study the effect of toxins on the level of apoptosis, ROS, mitochondrial potential, GSH, and ATP in CHO‐K1 cells. We show that all the tested toxins are able to dose dependently block the induction of apoptosis triggered by AC‐1001 H3 and reduce the level of natural apoptosis in CHO‐K1 cells. Cell incubation with apoptosis inducer AC‐1001 H3 in the presence and absence of toxins causes an increase in the intracellular concentrations of ROS, ATP, and mitochondrial potential and decreases the GSH concentration. The present study reveals the antiapoptotic effect of a number of arthropod peptide toxins. The toxins studied can represent a novel approach used in the treatment of pathologies associated with the activation of apoptotic mechanisms. 相似文献
7.
Sebastian Fernandez-Pol Zdenek Slouka Souvik Bhattacharjee Yana Fedotova Stefan Freed Xiuli An Anthony A. Holder Estela Campanella Philip S. Low Narla Mohandas Kasturi Haldar 《Eukaryotic cell》2013,12(9):1179-1191
Eukaryotic parasites of the genus Plasmodium cause malaria by invading and developing within host erythrocytes. Here, we demonstrate that PfShelph2, a gene product of Plasmodium falciparum that belongs to the Shewanella-like phosphatase (Shelph) subfamily, selectively hydrolyzes phosphotyrosine, as shown for other previously studied Shelph family members. In the extracellular merozoite stage, PfShelph2 localizes to vesicles that appear to be distinct from those of rhoptry, dense granule, or microneme organelles. During invasion, PfShelph2 is released from these vesicles and exported to the host erythrocyte. In vitro, PfShelph2 shows tyrosine phosphatase activity against the host erythrocyte protein Band 3, which is the most abundant tyrosine-phosphorylated species of the erythrocyte. During P. falciparum invasion, Band 3 undergoes dynamic and rapid clearance from the invasion junction within 1 to 2 s of parasite attachment to the erythrocyte. Release of Pfshelph2 occurs after clearance of Band 3 from the parasite-host cell interface and when the parasite is nearly or completely enclosed in the nascent vacuole. We propose a model in which the phosphatase modifies Band 3 in time to restore its interaction with the cytoskeleton and thus reestablishes the erythrocyte cytoskeletal network at the end of the invasion process. 相似文献
8.
Disease-causing aberrations in the normal function of a gene define that gene as a disease gene. Proving a causal link between a gene and a disease experimentally is expensive and time-consuming. Comprehensive prioritization of candidate genes prior to experimental testing drastically reduces the associated costs. Computational gene prioritization is based on various pieces of correlative evidence that associate each gene with the given disease and suggest possible causal links. A fair amount of this evidence comes from high-throughput experimentation. Thus, well-developed methods are necessary to reliably deal with the quantity of information at hand. Existing gene prioritization techniques already significantly improve the outcomes of targeted experimental studies. Faster and more reliable techniques that account for novel data types are necessary for the development of new diagnostics, treatments, and cure for many diseases.
This article is part of the “Translational Bioinformatics" collection for PLOS Computational Biology.
What to Learn in This Chapter
- Identification of specific disease genes is complicated by gene pleiotropy, polygenic nature of many diseases, varied influence of environmental factors, and overlying genome variation.
- Gene prioritization is the process of assigning likelihood of gene involvement in generating a disease phenotype. This approach narrows down, and arranges in the order of likelihood in disease involvement, the set of genes to be tested experimentally.
- The gene “priority" in disease is assigned by considering a set of relevant features such as gene expression and function, pathway involvement, and mutation effects.
- In general, disease genes tend to 1) interact with other disease genes, 2) harbor functionally deleterious mutations, 3) code for proteins localizing to the affected biological compartment (pathway, cellular space, or tissue), 4) have distinct sequence properties such as longer length and a higher number of exons, 5) have more orthologues and fewer paralogues.
- Data sources (directly experimental, extracted from knowledge-bases, or text-mining based) and mathematical/computational models used for gene prioritization vary widely.
9.
Wouter L. W. Hazenbos Kimberly K. Kajihara Richard Vandlen J. Hiroshi Morisaki Sophie M. Lehar Mark J. Kwakkenbos Tim Beaumont Arjen Q. Bakker Qui Phung Lee R. Swem Satish Ramakrishnan Janice Kim Min Xu Ishita M. Shah Binh An Diep Tao Sai Andrew Sebrell Yana Khalfin Angela Oh Chris Koth S. Jack Lin Byoung-Chul Lee Magnus Strandh Klaus Koefoed Peter S. Andersen Hergen Spits Eric J. Brown Man-Wah Tan Sanjeev Mariathasan 《PLoS pathogens》2013,9(10)
Infection of host tissues by Staphylococcus aureus and S. epidermidis requires an unusual family of staphylococcal adhesive proteins that contain long stretches of serine-aspartate dipeptide-repeats (SDR). The prototype member of this family is clumping factor A (ClfA), a key virulence factor that mediates adhesion to host tissues by binding to extracellular matrix proteins such as fibrinogen. However, the biological siginificance of the SDR-domain and its implication for pathogenesis remain poorly understood. Here, we identified two novel bacterial glycosyltransferases, SdgA and SdgB, which modify all SDR-proteins in these two bacterial species. Genetic and biochemical data demonstrated that these two glycosyltransferases directly bind and covalently link N-acetylglucosamine (GlcNAc) moieties to the SDR-domain in a step-wise manner, with SdgB appending the sugar residues proximal to the target Ser-Asp repeats, followed by additional modification by SdgA. GlcNAc-modification of SDR-proteins by SdgB creates an immunodominant epitope for highly opsonic human antibodies, which represent up to 1% of total human IgG. Deletion of these glycosyltransferases renders SDR-proteins vulnerable to proteolysis by human neutrophil-derived cathepsin G. Thus, SdgA and SdgB glycosylate staphylococcal SDR-proteins, which protects them against host proteolytic activity, and yet generates major eptopes for the human anti-staphylococcal antibody response, which may represent an ongoing competition between host and pathogen. 相似文献
10.
Nina Gabarayeva Valentina Grigorjeva Yana Kosenko 《Plant Systematics and Evolution》2013,299(6):1013-1035
Developmental stages during the tetrad period were examined in detail by transmission electron microscopy with an emphasis on substructure. Our purpose was to find out whether the sequence of sporoderm developmental events provides additional evidence for our recent hypothesis on the underlying cause of exine ontogeny as a sequence of self-assembling micellar mesophases initiated by genomically given physicochemical parameters. Osmiophilic globules encrusting the surface of postmeiotic microspores and tapetal cells are temporary prepattern units which come first. The second prepattern structures are highly ordered bundles of microfilaments and microtubules which determine the position of microspore surface invaginations and clusters of the glycocalyx inside them. The first glycocalyx units are microgranules which during the middle tetrad stage rearrange into radially oriented rod-like units. The latter form lens-like clusters of the glycocalyx-1, located inside the invaginations. These clusters predestine the position of the future luminae in the exine reticulum. The second glycocalyx layer is laid down as a continuous layer over the whole microspore surface and has similar substructure, that is radial rods. Glycocalyx-2 is a framework for procolumellae which appear at the late tetrad stage. Therefore, the sequence of substructural units in the primexine is: globules, microgranules, rod-like units, and layers of radially oriented rods tightly packed in the periplasmic space. This sequence corresponds to the first three mesophases of self-assembling micelles: spherical micelles, cylindrical micelles, and layers of hexagonally packed cylindrical micelles (middle mesophase). We observed the same sequence in other species during primexine development, and the findings of this study provide new evidence for our hypothesis. 相似文献