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1.
Bunge M Adrian L Kraus A Opel M Lorenz WG Andreesen JR Görisch H Lechner U 《Nature》2003,421(6921):357-360
Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs and PCDFs) are among the most notorious environmental pollutants. Some congeners, particularly those with lateral chlorine substitutions at positions 2, 3, 7 and 8, are extremely toxic and carcinogenic to humans. One particularly promising mechanism for the detoxification of PCDDs and PCDFs is microbial reductive dechlorination. So far only a limited number of phylogenetically diverse anaerobic bacteria have been found that couple the reductive dehalogenation of chlorinated compounds--the substitution of a chlorine for a hydrogen atom--to energy conservation and growth in a process called dehalorespiration. Microbial dechlorination of PCDDs occurs in sediments and anaerobic mixed cultures from sediments, but the responsible organisms have not yet been identified or isolated. Here we show the presence of a Dehalococcoides species in four dioxin-dechlorinating enrichment cultures from a freshwater sediment highly contaminated with PCDDs and PCDFs. We also show that the previously described chlorobenzene-dehalorespiring bacterium Dehalococcoides sp. strain CBDB1 (ref. 3) is able to reductively dechlorinate selected dioxin congeners. Reductive dechlorination of 1,2,3,7,8-pentachlorodibenzo-p-dioxin (PeCDD) demonstrates that environmentally significant dioxins are attacked by this bacterium. 相似文献
2.
Maria C. Shina Annette Müller-Taubenberger Can Ünal Michael Schleicher Michael Steinert Ludwig Eichinger Rolf Müller Rosemarie Blau-Wasser Gernot Glöckner Angelika A. Noegel 《Cellular and molecular life sciences : CMLS》2011,68(2):303-313
Dictyostelium discoideum harbors a short (CRN12) and a long coronin (CRN7) composed of one and two beta-propellers, respectively. They are primarily
present in the cell cortex and cells lacking CRN12 (corA
−) or CRN7 (corB
−) have defects in actin driven processes. We compared the characteristics of a mutant cell line (corA
−
/corB
−) lacking CRN12 and CRN7 with the single mutants focusing on cytokinesis, phagocytosis, chemotaxis and development. Cytokinesis,
uptake of small particles, and developmental defects were not enhanced in the corA
−
/corB
− strain as compared to the single mutants, whereas motility and phagocytosis of yeast particles were more severely impaired.
It appears that although both proteins affect the same processes they do not act in a redundant manner. Rather, they often
act antagonistically, which is in accordance with their proposed roles in the actin cytoskeleton where CRN12 acts in actin
disassembly whereas CRN7 stabilizes actin filaments and protects them from disassembly. 相似文献
3.
Vivek S. Peche Tad A. Holak Bhagyashri D. Burgute Kosmas Kosmas Sushant P. Kale F. Thomas Wunderlich Fatiha Elhamine Robert Stehle Gabriele Pfitzer Klaus Nohroudi Klaus Addicks Florian Stöckigt Jan W. Schrickel Julia Gallinger Michael Schleicher Angelika A. Noegel 《Cellular and molecular life sciences : CMLS》2013,70(3):527-543
Cyclase-associated proteins are highly conserved proteins that have a role in the regulation of actin dynamics. Higher eukaryotes have two isoforms, CAP1 and CAP2. To study the in vivo function of CAP2, we generated mice in which the CAP2 gene was inactivated by a gene-trap approach. Mutant mice showed a decrease in body weight and had a decreased survival rate. Further, they developed a severe cardiac defect marked by dilated cardiomyopathy (DCM) associated with drastic reduction in basal heart rate and prolongations in atrial and ventricular conduction times. Moreover, CAP2-deficient myofibrils exhibited reduced cooperativity of calcium-regulated force development. At the microscopic level, we observed disarrayed sarcomeres with development of fibrosis. We analyzed CAP2’s role in actin assembly and found that it sequesters G-actin and efficiently fragments filaments. This activity resides completely in its WASP homology domain. Thus CAP2 is an essential component of the myocardial sarcomere and is essential for physiological functioning of the cardiac system, and a deficiency leads to DCM and various cardiac defects. 相似文献
4.
Summary Changing the L: D time ratio of an entraining light-dark regime leads to characteristic alterations of the resynchronization behaviour of the circadian activity rhythms in night monkeys (Aotus trivirgatus) and African fruit bats (Rousettus aegyptiacus) after 8 h advance and delay shifts of the LD-Zeitgeber. Reduced speed of re-entrainment and occurrence of antidromic resynchronization point to a lower Zeitgeber strength of 24-h LD-cycles with a prolonged D-phase.Supported by the Deutsche Forschungsgemeinschaft (Er 59/8). 相似文献
5.
Schmeisser MJ Ey E Wegener S Bockmann J Stempel AV Kuebler A Janssen AL Udvardi PT Shiban E Spilker C Balschun D Skryabin BV Dieck St Smalla KH Montag D Leblond CS Faure P Torquet N Le Sourd AM Toro R Grabrucker AM Shoichet SA Schmitz D Kreutz MR Bourgeron T Gundelfinger ED Boeckers TM 《Nature》2012,486(7402):256-260
Autism spectrum disorders comprise a range of neurodevelopmental disorders characterized by deficits in social interaction and communication, and by repetitive behaviour. Mutations in synaptic proteins such as neuroligins, neurexins, GKAPs/SAPAPs and ProSAPs/Shanks were identified in patients with autism spectrum disorder, but the causative mechanisms remain largely unknown. ProSAPs/Shanks build large homo- and heteromeric protein complexes at excitatory synapses and organize the complex protein machinery of the postsynaptic density in a laminar fashion. Here we demonstrate that genetic deletion of ProSAP1/Shank2 results in an early, brain-region-specific upregulation of ionotropic glutamate receptors at the synapse and increased levels of ProSAP2/Shank3. Moreover, ProSAP1/Shank2(-/-) mutants exhibit fewer dendritic spines and show reduced basal synaptic transmission, a reduced frequency of miniature excitatory postsynaptic currents and enhanced N-methyl-d-aspartate receptor-mediated excitatory currents at the physiological level. Mutants are extremely hyperactive and display profound autistic-like behavioural alterations including repetitive grooming as well as abnormalities in vocal and social behaviours. By comparing the data on ProSAP1/Shank2(-/-) mutants with ProSAP2/Shank3αβ(-/-) mice, we show that different abnormalities in synaptic glutamate receptor expression can cause alterations in social interactions and communication. Accordingly, we propose that appropriate therapies for autism spectrum disorders are to be carefully matched to the underlying synaptopathic phenotype. 相似文献
6.
Lu W Schneider M Neumann S Jaeger VM Taranum S Munck M Cartwright S Richardson C Carthew J Noh K Goldberg M Noegel AA Karakesisoglou I 《Cellular and molecular life sciences : CMLS》2012,69(20):3493-3509
Nesprins-1/-2/-3/-4 are nuclear envelope proteins, which connect nuclei to the cytoskeleton. The largest nesprin-1/-2 isoforms (termed giant) tether F-actin through their N-terminal actin binding domain (ABD). Nesprin-3, however, lacks an ABD and associates instead to plectin, which binds intermediate filaments. Nesprins are integrated into the outer nuclear membrane via their C-terminal KASH-domain. Here, we show that nesprin-1/-2 ABDs physically and functionally interact with nesprin-3. Thus, both ends of nesprin-1/-2 giant are integrated at the nuclear surface: via the C-terminal KASH-domain and the N-terminal ABD-nesprin-3 association. Interestingly, nesprin-2 ABD or KASH-domain overexpression leads to increased nuclear areas. Conversely, nesprin-2 mini (contains the ABD and KASH-domain but lacks the massive nesprin-2 giant rod segment) expression yields smaller nuclei. Nuclear shrinkage is further enhanced upon nesprin-3 co-expression or microfilament depolymerization. Our findings suggest that multivariate intermolecular nesprin interactions with the cytoskeleton form a lattice-like filamentous network covering the outer nuclear membrane, which determines nuclear size. 相似文献
7.
Saliba KJ Martin RE Bröer A Henry RI McCarthy CS Downie MJ Allen RJ Mullin KA McFadden GI Bröer S Kirk K 《Nature》2006,443(7111):582-585
As the malaria parasite, Plasmodium falciparum, grows within its host erythrocyte it induces an increase in the permeability of the erythrocyte membrane to a range of low-molecular-mass solutes, including Na+ and K+ (ref. 1). This results in a progressive increase in the concentration of Na+ in the erythrocyte cytosol. The parasite cytosol has a relatively low Na+ concentration and there is therefore a large inward Na+ gradient across the parasite plasma membrane. Here we show that the parasite exploits the Na+ electrochemical gradient to energize the uptake of inorganic phosphate (P(i)), an essential nutrient. P(i) was taken up into the intracellular parasite by a Na+-dependent transporter, with a stoichiometry of 2Na+:1P(i) and with an apparent preference for the monovalent over the divalent form of P(i). A P(i) transporter (PfPiT) belonging to the PiT family was cloned from the parasite and localized to the parasite surface. Expression of PfPiT in Xenopus oocytes resulted in Na+-dependent P(i) uptake with characteristics similar to those observed for P(i) uptake in the parasite. This study provides new insight into the significance of the malaria-parasite-induced alteration of the ionic composition of its host cell. 相似文献
8.
Chiral recognition in dimerization of adsorbed cysteine observed by scanning tunnelling microscopy 总被引:3,自引:0,他引:3
Stereochemistry plays a central role in controlling molecular recognition and interaction: the chemical and biological properties of molecules depend not only on the nature of their constituent atoms but also on how these atoms are positioned in space. Chiral specificity is consequently fundamental in chemical biology and pharmacology and has accordingly been widely studied. Advances in scanning probe microscopies now make it possible to probe chiral phenomena at surfaces at the molecular level. These methods have been used to determine the chirality of adsorbed molecules, and to provide direct evidence for chiral discrimination in molecular interactions and the spontaneous resolution of adsorbates into extended enantiomerically pure overlayers. Here we report scanning tunnelling microscopy studies of cysteine adsorbed to a (110) gold surface, which show that molecular pairs formed from a racemic mixture of this naturally occurring amino acid are exclusively homochiral, and that their binding to the gold surface is associated with local surface restructuring. Density-functional theory calculations indicate that the chiral specificity of the dimer formation process is driven by the optimization of three bonds on each cysteine molecule. These findings thus provide a clear molecular-level illustration of the well known three-point contact model for chiral recognition in a simple bimolecular system. 相似文献
9.
Glöckner G Eichinger L Szafranski K Pachebat JA Bankier AT Dear PH Lehmann R Baumgart C Parra G Abril JF Guigó R Kumpf K Tunggal B Cox E Quail MA Platzer M Rosenthal A Noegel AA;Dictyostelium Genome Sequencing Consortium 《Nature》2002,418(6893):79-85
The genome of the lower eukaryote Dictyostelium discoideum comprises six chromosomes. Here we report the sequence of the largest, chromosome 2, which at 8 megabases (Mb) represents about 25% of the genome. Despite an A + T content of nearly 80%, the chromosome codes for 2,799 predicted protein coding genes and 73 transfer RNA genes. This gene density, about 1 gene per 2.6 kilobases (kb), is surpassed only by Saccharomyces cerevisiae (one per 2 kb) and is similar to that of Schizosaccharomyces pombe (one per 2.5 kb). If we assume that the other chromosomes have a similar gene density, we can expect around 11,000 genes in the D. discoideum genome. A significant number of the genes show higher similarities to genes of vertebrates than to those of other fully sequenced eukaryotes. This analysis strengthens the view that the evolutionary position of D. discoideum is located before the branching of metazoa and fungi but after the divergence of the plant kingdom, placing it close to the base of metazoan evolution. 相似文献
10.
D. Giesecke Perdita v. Wallenberg Angelika Fabritius 《Cellular and molecular life sciences : CMLS》1980,36(5):571-572
Summary D(-)Lactate is produced in significant amounts together with L(+)lactate in the stomach of normal experimental rats. It is absorbed into the blood and constitutes a physiological isomer in this animal species. 相似文献