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1.
Summary Roots ofVicia faba L. immersed in a buffer solution were found to release esterases into the environment. The substrate -naphthylacetate was taken up by the roots and degraded, the hydrolysis products being released back into the surrounding medium. 相似文献
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Nicole Schwarz Jessica Pruessmeyer Franz M. Hess Daniela Dreymueller Elena Pantaler Anne Koelsch Reinhard Windoffer Matthias Voss Alisina Sarabi Christian Weber Antonio S. Sechi Stefan Uhlig Andreas Ludwig 《Cellular and molecular life sciences : CMLS》2010,67(24):4233-4248
The surface-expressed transmembrane CX3C chemokine ligand 1 (CX3CL1/fractalkine) induces firm adhesion of leukocytes expressing its receptor CX3CR1. After shedding by the disintegrins and metalloproteinases (ADAM) 10 and 17, CX3CL1 also acts as soluble leukocyte chemoattractant. Here, we demonstrate that transmembrane CX3CL1 expressed on both endothelial and epithelial cells induces leukocyte transmigration. To investigate the underlying mechanism, we generated CX3CR1 variants lacking the intracellular aspartate-arginine-tyrosine (DRY) motif or the intracellular C-terminus which led to a defect in intracellular calcium response and impaired ligand uptake, respectively. While both variants effectively mediated firm cell adhesion, they failed to induce transmigration and rather mediated retention of leukocytes on the CX3CL1-expressing cell layer. Targeting of ADAM10 led to increased adhesion but reduced transmigration in response to transmembrane CX3CL1, while transmigration towards soluble CX3CL1 was not affected. Thus, transmembrane CX3CL1 mediates leukocyte transmigration via the DRY motif and C-terminus of CX3CR1 and the activity of ADAM10. 相似文献
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Bovine erythrocyte acetylcholinesterase and human plasma cholinesterase are irreversibly inhibited by diethylmesoxalate hydrate, the inhibition potency being comparable to that of certian insecticidal organophosphates and carbamates. Insect cholinesterases, however, appear to be much less affected by diethylmesoxalate hydrate. The compound was also found to inhibit the hydrolysis of paraoxon by rabbit plasma A-esterase, but in a reversible mode. 相似文献
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Infantile obesity and later weight control in the baboon 总被引:1,自引:0,他引:1
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J. K. Walter V. Castro M. Voss K. Gast C. Rueckert J. Piontek Ingolf E. Blasig 《Cellular and molecular life sciences : CMLS》2009,66(22):3655-3662
Occludin is a self-associating transmembrane tight junction protein affected in oxidative stress. However, its function is
unknown. The cytosolic C-terminal tail contains a coiled coil-domain forming dimers contributing to the self-association.
Studying the hypothesis that the self-association is redox-sensitive, we found that the dimerization of the domain depended
on the sulfhydryl concentration of the environment in low-millimolar range. Under physiological conditions, monomers and dimers
were detected. Masking the sulfhydryl residues in the domain prevented the dimerization but affected neither its helical structure
nor cylindric shape. Incubation of cell extracts containing full-length occludin with sulfhydryl reagents prevented the dimerization;
a cysteine/alanine exchange mutant also did not show dimer formation. This demonstrates, for the first time, that disulfide
bridge formation of the domain is involved in the occludin dimerization. It is concluded that the redox-dependent dimerization
of occludin may play a regulatory role in the tight junction assembly under physiological and pathological conditions. 相似文献
7.
Summary Inhibition constants of several formamidines, their corresponding formanilides and other representatives of compounds derived from aniline, such as phenylureas, N-phenyl-carbamates and acylanilides, were determined for rat liver monoamine oxidase. The reversability of the inhibition and the lack of correlation between inhibition potencies and toxicities of the compounds tested add to the opinion that MAO inhibition is not a prominent factor in chlordimeform poisoning. 相似文献
8.
Chromosome 5 allele loss in human colorectal carcinomas 总被引:18,自引:0,他引:18
E Solomon R Voss V Hall W F Bodmer J R Jass A J Jeffreys F C Lucibello I Patel S H Rider 《Nature》1987,328(6131):616-619
That the sporadic and inherited forms of a particular cancer could both result from mutations in the same gene was first proposed by Knudson. He further proposed that these mutations act recessively at the cellular level, and that both copies of the gene must be lost for the cancer to develop. In sporadic cases both events occur somatically whereas in dominant familial cases susceptibility is inherited through a germline mutation and the cancer develops after a somatic change in the homologous allele. This model has since been substantiated in the case of retinoblastoma, Wilms tumour, acoustic neuroma and several other tumours, in which loss of heterozygosity was shown in tumour material compared to normal tissue from the same patient. The dominantly inherited disorder, familial adenomatous polyposis (FAP, also called familial polyposis coli), which gives rise to multiple adenomatous polyps in the colon that have a relatively high probability of progressing to a malignant adenocarcinoma, provides a basis for studying recessive genes in the far more common colorectal carcinomas using this approach. Following a clue as to the location of the FAP gene given by a case report of an individual with an interstitial deletion of chromosome 5q, who had FAP and multiple developmental abnormalities, we have examined sporadic colorectal adenocarcinomas for loss of alleles on chromosome 5. Using a highly polymorphic 'minisatellite' probe which maps to chromosome 5q we have shown that at least 20% of this highly heterogeneous set of tumours lose one of the alleles present in matched normal tissue. This parallels the assignment of the FAP gene to chromosome 5 (see accompanying paper) and suggests that becoming recessive for this gene may be a critical step in the progression of a relatively high proportion of colorectal cancers. 相似文献
9.
Type Ia supernovae are exploding stars that are used to measure the accelerated expansion of the Universe and are responsible for most of the iron ever produced. Although there is general agreement that the exploding star is a white dwarf in a binary system, the exact configuration and trigger of the explosion is unclear, which could hamper their use for precision cosmology. Two families of progenitor models have been proposed. In the first, a white dwarf accretes material from a companion until it exceeds the Chandrasekhar mass, collapses and explodes. Alternatively, two white dwarfs merge, again causing catastrophic collapse and an explosion. It has hitherto been impossible to determine if either model is correct. Here we report the discovery of an object in pre-supernova archival X-ray images at the position of the recent type Ia supernova (2007on) in the elliptical galaxy NGC 1404. Deep optical images (also archival) show no sign of this object. From this we conclude that the X-ray source is the progenitor of the supernova, which favours the accretion model for this supernova, although the host galaxy is older (6-9 Gyr) than the age at which the explosions are predicted in the accreting models. 相似文献
10.
Hakim O Resch W Yamane A Klein I Kieffer-Kwon KR Jankovic M Oliveira T Bothmer A Voss TC Ansarah-Sobrinho C Mathe E Liang G Cobell J Nakahashi H Robbiani DF Nussenzweig A Hager GL Nussenzweig MC Casellas R 《Nature》2012,484(7392):69-74
Recurrent chromosomal translocations underlie both haematopoietic and solid tumours. Their origin has been ascribed to selection of random rearrangements, targeted DNA damage, or frequent nuclear interactions between translocation partners; however, the relative contribution of each of these elements has not been measured directly or on a large scale. Here we examine the role of nuclear architecture and frequency of DNA damage in the genesis of chromosomal translocations by measuring these parameters simultaneously in cultured mouse B lymphocytes. In the absence of recurrent DNA damage, translocations between Igh or Myc and all other genes are directly related to their contact frequency. Conversely, translocations associated with recurrent site-directed DNA damage are proportional to the rate of DNA break formation, as measured by replication protein A accumulation at the site of damage. Thus, non-targeted rearrangements reflect nuclear organization whereas DNA break formation governs the location and frequency of recurrent translocations, including those driving B-cell malignancies. 相似文献