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281.
The SpvB protein from Salmonella enterica was recently discovered as an actin-ADP-ribosylating toxin. SpvB is most likely delivered via a type-III secretion system into eukaryotic cells and does not have a binding/translocation component. This is in contrast to the family of binary actin-ADP-ribosylating toxins from various Bacillus and Clostridium species. However, there are homologies in amino acid sequences between the C-terminal domain of SpvB and the catalytic domains of the actin-ADP-ribosylating toxins such as C2 toxin from Clostridium botulinum and iota toxin from Clostridium perfringens. We compared the biochemical properties of the catalytic C-terminal domain of SpvB (C/SpvB) with the enzyme components of C2 toxin and iota toxin. The specificity of C/SpvB concerning the modification of G- or F-actin was comparable to the C2 and iota toxins, although there were distinct differences regarding the recognition of actin isoforms. C/SpvB and iota toxin modify both muscle alpha-actin and nonmuscle beta/gamma-actin, whereas C2 toxin only modifies beta/gamma-actin. In contrast to the iota and C2 toxins, C/SpvB possessed no detectable glycohydrolase activity in the absence of a protein substrate. The maximal reaction rates were comparable for all toxins, whereas variable K(m) values for NAD were evident. We identified arginine-177 as the modification site for C/SpvB with the actin homologue protein Act88F from Drosophila. 相似文献
282.
Shkumatov VM Frolova Ns Rudaia EV Faletrov IaV Mauerberger S Barth G 《Prikladnaia biokhimiia i mikrobiologiia》2006,42(5):539-546
The relationship between 17alpha-hydroxylation and 20-oxidation-reduction of progesterone and some of its derivatives was studied in yeast strains Saccharomyces cerevisiae YEp51alpha, Yarrowia lipolytica E129A15, and expressing cytochrome P450c17. The key metabolites were found to be 17alpha-hydroxyprogesterone and 17alpha,20(alpha,beta)-dihydroxypregn-4-ene-3-ones. The bioconversion pathways of pregn-4-ene-20(alpha,beta)-ol-3-ones were determined. They included cycles of 20-oxidation, 17alpha-hydroxylation, and stereospecific 20-reduction. The efficiency and kinetic parameters of steroid bioconversion by the recombinant strains were determined. The role of yeast analogs of mammalian steroid dehydrogenases is discussed. It was found that any of the desired derivatives, 17alpha-hydroxyprogesterone or progesterone 17alpha,20(alpha,beta)-diols, could be obtained from progesterone. 相似文献
283.
The splenic marginal zone in humans and rodents: an enigmatic compartment and its inhabitants 总被引:3,自引:3,他引:0
The role of the spleen in B memory cell development and maintenance is attracting increased attention. Studies in mice and rats have indicated that memory functions are associated with large B cells residing in the marginal zone (MZ) of the spleen. Although the cellular composition of the MZ is relatively well known in these species, controversies exist about the function of MZ B cells, their dependence on the presence of the spleen and the stage at which their development branches from that of recirculating follicular B cells. Additional confusion has arisen with respect to MZ B cells in humans, because the microscopic anatomy of the human splenic MZ differs decisively from that of rodents. Several recent publications indicate that the functional and migratory properties of human MZ B cells may be species-specific. The hypothesis derived from these publications and from our immunohistological observations implies that at least a major number of human splenic CD27+ MZ B cells are migratory. Phenotypic data suggest a recirculation pathway between the spleen and mucosal tissues in humans. 相似文献
284.
ANDREA FERREIRA DA COSTA PABLO JOSÉ FRANCISCO PENA RODRIGUES MARIA DAS GRAÇAS LAPA WANDERLEY 《Botanical journal of the Linnean Society. Linnean Society of London》2009,159(1):163-181
The species related to Vriesea paraibica (Bromeliaceae, Tillandsioideae) have controversial taxonomic limits. For several decades, this group has been identified in herbarium collections as V. × morreniana, an artificial hybrid that does not grow in natural habitats. The aim of this study was to assess the morphological variation in the V. paraibica complex through morphometric analyses of natural populations. Two sets of analyses were performed: the first involved six natural populations (G1) and the second was carried out on taxa that emerged from the first analysis, but using material from herbarium collections (G2). Univariate ANOVA was used, as well as discriminant analysis of 16 morphometric variables in G1 and 18 in G2. The results of the analyses of the two groups were similar and led to the selection of diagnostic traits of four species. Lengths of the lower and median floral bracts were significant for the separation of red and yellow floral bracts. Vriesea paraibica and V. interrogatoria have red bracts; these two species are differentiated by the widths of the lower and median portions of the inflorescence and by scape length. These structures are larger in the former and smaller in the latter. Of the species with yellow floral bracts, V. eltoniana is distinguished by longer leaf blades and scapes and V. flava is characterized by its shorter sepal lengths. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159 , 163–181. 相似文献
285.
Roland Moll Evelyn Sievers Bettina Hämmerling Ansgar Schmidt Mareike Barth Caecilia Kuhn Christine Grund Ilse Hofmann Werner W. Franke 《Cell and tissue research》2009,335(1):109-141
The lymph node sinus are channel structures of unquestionable importance in immunology and pathology, specifically in the
filtering of the lymph, the transport and processing of antigens, the adhesion and migration of immune cells, and the spread
of metastatic cancer cells. Our knowledge of the cell and molecular biology of the sinus-forming cells is still limited, and
the origin and biological nature of these cells have long been a matter of debate. Here, we review the relevant literature
and present our own experimental results, in particular concerning molecular markers of intercellular junctions and cell differentiation.
We show that both the monolayer cells lining the sinus walls and the intraluminal virgultar cell meshwork are indeed different
morphotypes of the same basic endothelial cell character, as demonstrated by the presence of a distinct spectrum of general
and lymphatic endothelial markers, and we therefore refer to these cells as sinus endothelial/virgultar cells (SEVCs). These
cells are connected by unique adhering junctions, termed complexus adhaerentes, characterized by the transmembrane glycoprotein VE-cadherin, combined with the desmosomal plaque protein desmoplakin, several
adherens junction plaque proteins including α- and β-catenin and p120 catenin, and components of the tight junction ensemble,
specifically claudin-5 and JAM-A, and the plaque protein ZO-1. We show that complexus adhaerentes are involved in the tight three-dimensional integration of the virgultar network of SEVC processes along extracellular guidance
structures composed of paracrystalline collagen bundle “stays”. Overall, the SEVC system might be considered as a local and
specific modification of the general lymphatic vasculature system. Finally, physiological and pathological alterations of
the SEVC system will be presented, and the possible value of the molecular markers described in histological diagnoses of
autochthonous lymph node tumors will be discussed.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
Werner W. FrankeEmail: |
286.
287.
Jorge Molina Clemens F. Schaber Friedrich G. Barth 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2009,195(11):1031-1041
The metatarsal lyriform organ of the spider Cupiennius salei is a vibration detector consisting of 21 cuticular slits supplied by two sensory cells each, one ending in the outer and
the other at the inner slit membrane. In search of functional differences between the two cell types due to differences in
stimulus transmission, we analyzed (1) the adaptation of responses to electrical stimulation, (2) the thresholds for mechanical
stimulation and (3) the representation of male courtship vibrations using intracellular recording and staining techniques.
Single- and multi-spiking receptor neurons were found among both cell types, which showed high-pass filter characteristics.
Below 100-Hz threshold, tarsal deflections were between 1° and 10°. At higher frequencies, they decreased down to values as
small as 0.05°, corresponding to 4.5-nm tarsal deflection in the most sensitive cases. Different slits in the organ and receptor
cells with slow or fast adaptation did not differ in this regard. When stimulated with male courtship vibrations, both types
of receptor cells again did not differ significantly regarding number of action potentials, latency and synchronization coefficients.
Surprisingly, the differences in dendrite coupling were not reflected by the physiological responses of the two cell types
innervating the slits. 相似文献
288.
Holz M Förster A Mauersberger S Barth G 《Applied microbiology and biotechnology》2009,81(6):1087-1096
The yeast Yarrowia lipolytica secretes high amounts of various organic acids, like citric acid (CA) and isocitric acid (ICA) under an excess of carbon
source and several conditions of growth limitation. Depending on the carbon source used, Y. lipolytica strains produce a mixture of CA and ICA in a characteristic ratio. To examine whether this CA/ICA product ratio can be influenced
by gene–dose-dependent overexpression of aconitase (ACO)-encoding gene ACO1, a recombinant Y. lipolytica strain was constructed containing multiple copies of ACO1. The high-level expression of ACO in the ACO1 multicopy integrative transformant resulted in a shift of the CA/ICA product pattern into the direction of ICA. On sunflower
oil, a striking increase of the ICA proportion from 35–49% to 66–71% was observed compared to wild-type strains without influencing
the total amount of acids (CA and ICA) produced. On glycerol, glucose or sucrose, the ICA proportion increased only moderately
from 10–12% to 13–17%. This moderate shift into the direction of ICA was also observed in an icl1-defective strain. 相似文献
289.
Regulation of endosomal clathrin and retromer‐mediated endosome to Golgi retrograde transport by the J‐domain protein RME‐8
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Anbing Shi Lin Sun Riju Banerjee Michael Tobin Yinhua Zhang Barth D Grant 《The EMBO journal》2009,28(21):3290-3302
After endocytosis, most cargo enters the pleiomorphic early endosomes in which sorting occurs. As endosomes mature, transmembrane cargo can be sequestered into inwardly budding vesicles for degradation, or can exit the endosome in membrane tubules for recycling to the plasma membrane, the recycling endosome, or the Golgi apparatus. Endosome to Golgi transport requires the retromer complex. Without retromer, recycling cargo such as the MIG‐14/Wntless protein aberrantly enters the degradative pathway and is depleted from the Golgi. Endosome‐associated clathrin also affects the recycling of retrograde cargo and has been shown to function in the formation of endosomal subdomains. Here, we find that the Caemorhabditis elegans endosomal J‐domain protein RME‐8 associates with the retromer component SNX‐1. Loss of SNX‐1, RME‐8, or the clathrin chaperone Hsc70/HSP‐1 leads to over‐accumulation of endosomal clathrin, reduced clathrin dynamics, and missorting of MIG‐14 to the lysosome. Our results indicate a mechanism, whereby retromer can regulate endosomal clathrin dynamics through RME‐8 and Hsc70, promoting the sorting of recycling cargo into the retrograde pathway. 相似文献
290.
Rhea N. Coler Ajay Bhatia Jean-Francois Maisonneuve Peter Probst Brenda Barth Pamela Ovendale Hang Fang Mark Alderson Yves Lobet Joe Cohen Pascal Mettens & Steven G. Reed 《FEMS immunology and medical microbiology》2009,55(2):258-270
Chlamydia trachomatis infection is the most common sexually transmitted bacterial infection worldwide, with over 91 million cases estimated annually. An effective subunit vaccine against Chlamydia may require a multivalent subunit cocktail of antigens in a single formulation for broad coverage of a heterogeneous major histocompatibility complex population. Herein, we describe the identification of novel C. trachomatis antigens by CD4+ and CD8+ T-cell expression cloning, serological expression cloning, and an in silico analysis of the C. trachomatis genome. These antigens elicited human CD4+ T-cell responses, and a subset proved to be immunogenic and protective when administered as immunoprophylactic vaccines against C. trachomatis challenge. Candidate vaccines consisting of the prioritized C. trachomatis antigens adjuvanted in a GlaxoSmithKline proprietary AS01B adjuvant were prioritized based on induction of solid protection against challenge in C57BL/6 and BALB/c mice with C. trachomatis . Some of the vaccines prevented bacterial shedding and colonization of the upper genital tract to varying degrees by mechanisms that may include CD4+ T cells. 相似文献