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91.
Background
Anaplasma marginale, an obligate intracellular alphaproteobacterium in the order Rickettsiales, is a tick-borne pathogen and the leading cause of anaplasmosis in cattle worldwide. Complete genome sequencing of A. marginale revealed that it has a type IV secretion system (T4SS). The T4SS is one of seven known types of secretion systems utilized by bacteria, with the type III and IV secretion systems particularly prevalent among pathogenic Gram-negative bacteria. The T4SS is predicted to play an important role in the invasion and pathogenesis of A. marginale by translocating effector proteins across its membrane into eukaryotic target cells. However, T4SS effector proteins have not been identified and tested in the laboratory until now.Results
By combining computational methods with phylogenetic analysis and sequence identity searches, we identified a subset of potential T4SS effectors in A. marginale strain St. Maries and chose six for laboratory testing. Four (AM185, AM470, AM705 [AnkA], and AM1141) of these six proteins were translocated in a T4SS-dependent manner using Legionella pneumophila as a reporter system.Conclusions
The algorithm employed to find T4SS effector proteins in A. marginale identified four such proteins that were verified by laboratory testing. L. pneumophila was shown to work as a model system for A. marginale and thus can be used as a screening tool for A. marginale effector proteins. The first T4SS effector proteins for A. marginale have been identified in this work. 相似文献92.
Major glycolipids [monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), sulfoquinovosyldiacylglycerol (SQDG)) and phospholipids (phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylglycerol (PG)] as well as betaine lipid 1,2-diacylglycero-O-4'-(N,N,N-tri-methyl)-homoserine (DGTS) were isolated from Anfeltia tobuchiensis (Rhodophyta), Laminaria japonica, Sargassum pallidum (Phaeophyta), Ulva fenestrata (Chlorophyta) and Zostera marina (Embriophyta), harvested in the Sea of Japan. GC analysis of their fatty acid (FA) composition revealed that the n-6 polyunsaturated FAs (PUFAs) shared the most part of the sum of n-6 and n-3 PUFAs in PC and PE compared with glycolipids and PG. In algae, it was related to the prevalence of 20:4n-6 over 20:5n-3 in non-photosynthetic lipids. Percentage of n-6 PUFAs as well as the sum of n-3 and n-6 PUFAs decreased in the following sequence: PC-->PE-->PG. The saturation increased in the lines of MGDG-->DGDG-->SQDG and PC-->PE-->PG. PG was close to SQDG by the level of saturation. Distribution of C(18) and C(20) PUFAs in polar lipids depended on taxonomic position of macrophytes. Balance between C(18) and C(20) PUFAs was preferably shifted to the side of C(20) PUFAs in PC and PE that was observed in contrast to glycolipids and PG from L. japonica containing both series of FAs. The set of major FAs of polar lipid classes can essentially differ from each other and from total lipids of macrophytes. For example, MGDG was found to accumulate characteristic fatty acids 16:4n-3, 16:3n-3, 18:3n-6 and 18:4n-3, 20:3n-6 in U. fenestrata, Z. marina, L. japonica and S. pallidum, respectively. 相似文献
93.
94.
The peculiarities of the formation of colonies of dimorphous epilithic fungus Phaeococcomyces de Hoog isolated from marble were studied. The data obtained can be used for modeling the formation of colonies of dimorphous microscopic fungi. 相似文献
95.
Sud'ina GF Pushkareva MA Galkina SI Surkov SA Mehl M Ullrich V 《Bioscience reports》1999,19(6):547-558
Human polymorphonuclear leukocytes (PMN) were found to tightly adhere on endothelial (lines EAhy926 and ECV304) and collagen surfaces under the influence of the chemotherapeutic drug suramin. This was observed by scanning electron microscopy and quantitated by myeloperoxidase assays. Suramin also inhibited Ca2+ ionophore A23187-stimulated leukotriene (LT) synthesis in PMN interaction with endothelial cells or with collagen surface. Suramin decreased the release of radiolabeled arachidonic acid (AA) and 5-lip-oxygenase (5-LO) metabolites by prelabeled PMN stimulated with A23187. Using agents releasing the suramin-stimulated adhesion namely jasplakonolide and dextran sulfate, we observed a reversal of the suramin effect on leukotriene synthesis. Jasplakonolide released the adhesion of PMN on endothelial and collagen-coated surfaces and restored 5-LO activity. Dextran-sulfate released adhesion on collagen-coated surfaces and abolished suramin inhibition. Arachidonate could also overcome adhesion and inhibition of 5-LO. We conclude that suramin-induced tight attachment of PMN on to solid surfaces lead to decreased leukotriene synthesis during subsequent A23187 stimulation in the absence of exogenous substrates. 相似文献
96.
Isaac ISHAAYA Avner BARAZANI Svetlana KONTSEDALOV A. Rami HOROWITZ 《Entomological Research》2007,37(3):148-152
Efforts have been made during the past two decades to develop insecticides with selective properties that act specifically on biochemical sites present in particular insect groups, but whose properties differ from other insecticides. This approach has led to the discovery of compounds that affect the hormonal regulation of molting and developmental processes in insects; for example, ecdysone agonists, juvenile hormone mimics and chitin synthesis inhibitors. In addition, compounds that selectively interact with the insect nicotinic acetylcholine receptor, such as imidacloprid, acetamiprid and thiamethoxam, have been introduced for the control of aphids, whiteflies and other insect species. Natural products acting selectively on insect pests, such as avermectins, spinosad and azadirachtin, have been introduced for controlling selected groups of insect pests. Compounds acting on the nervous site that controls the sucking pump of aphids and whiteflies, such as pymetrozine, or respiration, such as diafenthiuron, have been introduced for controlling sucking pests. All the above compounds are important components in pest and resistance management programs. 相似文献
97.
Hakobyan S Harris CL van den Berg CW Fernandez-Alonso MC de Jorge EG de Cordoba SR Rivas G Mangione P Pepys MB Morgan BP 《The Journal of biological chemistry》2008,283(45):30451-30460
Binding of the complement regulatory protein, factor H, to C-reactive protein has been reported and implicated as the biological basis for association of the H402 polymorphic variant of factor H with macular degeneration. Published studies utilize solid-phase or fluid-phase binding assays to show that the factor H Y402 variant binds C-reactive protein more strongly than H402. Diminished binding of H402 variant to C-reactive protein in retinal drusen is posited to permit increased complement activation, driving inflammation and pathology. We used well validated native human C-reactive protein and pure factor H Y402H variants to test interactions. When factor H variants were incubated with C-reactive protein in the fluid phase at physiological concentrations, no association occurred. When C-reactive protein was immobilized on plastic, either non-specifically by adsorption in the presence of Ca(2+) to maintain its native fold and pentameric subunit assembly or by specific Ca(2+)-dependent binding to immobilized natural ligands, no specific binding of either factor H variant from the fluid phase was observed. In contrast, both factor H variants reproducibly bound to C-reactive protein immobilized in the absence of Ca(2+), conditions that destabilize the native fold and pentameric assembly. Both factor H variants strongly bound C-reactive protein that was denatured by heat treatment before immobilization, confirming interaction with denatured but not native C-reactive protein. We conclude that the reported binding of factor H to C-reactive protein results from denaturation of the C-reactive protein during immobilization. Differential binding to C-reactive protein, thus, does not explain association of the Y402H polymorphism with macular degeneration. 相似文献
98.
Altúzar-Molina Alma Lozano Luis Ortíz-Berrocal Marlene Ramírez Mario Martínez Lourdes de Lourdes Velázquez-Hernández María Dhar-Ray Swatismita Silvente Sonia Mariano Néstor Shishkova Svetlana Hernández Georgina Reddy Pallavolu M. 《Plant Molecular Biology Reporter》2020,38(2):262-281
Plant Molecular Biology Reporter - Legumes form symbiosis with rhizobia, which fix nitrogen for the benefit of host plant in return for carbon resources. Development of this unique symbiosis in... 相似文献
99.
100.
Olga S. Ostroumova Svetlana S. Efimova Ludmila V. Schagina 《The Journal of membrane biology》2013,246(12):985-991
The phloretin-induced reduction in the dipole potential of planar lipid bilayers containing cholesterol, ergosterol, stigmasterol, 7-dehydrocholesterol and 5α-androstan-3β-ol was investigated. It is shown that effects depend on the type and concentration of membrane sterol. It is supposed that the effectiveness of phloretin in reducing the dipole potential of the bilayers that contain cholesterol, ergosterol and 7-dehydrocholesterol correlates with the ordering and condensing effects. The role of the concentration-dependent ability of different sterols to promote lateral heterogeneity in membranes is also discussed. 相似文献