排序方式: 共有104条查询结果,搜索用时 46 毫秒
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Nuclear pore complexes (NPCs) assemble at the end of mitosis during nuclear envelope (NE) reformation and into an intact NE as cells progress through interphase. Although recent studies have shown that NPC formation occurs by two different molecular mechanisms at two distinct cell cycle stages, little is known about the molecular players that mediate the fusion of the outer and inner nuclear membranes to form pores. In this paper, we provide evidence that the transmembrane nucleoporin (Nup), POM121, but not the Nup107-160 complex, is present at new pore assembly sites at a time that coincides with inner nuclear membrane (INM) and outer nuclear membrane (ONM) fusion. Overexpression of POM121 resulted in juxtaposition of the INM and ONM. Additionally, Sun1, an INM protein that is known to interact with the cytoskeleton, was specifically required for interphase assembly and localized with POM121 at forming pores. We propose a model in which POM121 and Sun1 interact transiently to promote early steps of interphase NPC assembly. 相似文献
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André G?hler Adrian Hetzer Birte Holtfreter Marie Henrike Geisel Carsten Oliver Schmidt Ivo Steinmetz Thomas Kocher 《PloS one》2014,9(7)
Periodontitis is a multi-microbial oral infection with high prevalence among adults. Putative oral pathogens are commonly found in periodontally diseased individuals. However, these organisms can be also detected in the oral cavity of healthy subjects. This leads to the hypothesis, that alterations in the proportion of these organisms relative to the total amount of oral microorganisms, namely their abundance, rather than their simple presence might be important in the transition from health to disease. Therefore, we developed a quantitative molecular method to determine the abundance of various oral microorganisms and the portion of bacterial and archaeal nucleic acid relative to the total nucleic acid extracted from individual samples. We applied quantitative real-time PCRs targeting single-copy genes of periodontal bacteria and 16S-rRNA genes of Bacteria and Archaea. Testing tongue scrapings of 88 matched pairs of periodontally diseased and healthy subjects revealed a significantly higher abundance of P. gingivalis and a higher total bacterial abundance in diseased subjects. In fully adjusted models the risk of being periodontally diseased was significantly higher in subjects with high P. gingivalis and total bacterial abundance. Interestingly, we found that moderate abundances of A. actinomycetemcomitans were associated with reduced risk for periodontal disease compared to subjects with low abundances, whereas for high abundances, this protective effect leveled off. Moderate archaeal abundances were health associated compared to subjects with low abundances. In conclusion, our methodological approach unraveled associations of the oral flora with periodontal disease, which would have gone undetected if only qualitative data had been determined. 相似文献
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The excised group II intron bI1 from Saccharomyces cerevisiae can act as a ribozyme catalysing various chemical reactions with different substrate RNAs in vitro . Recently, we have described an editing-like RNA polymerization reaction catalysed by the bI1 intron lariat that proceeds in the 3'-->5'direction. Here we show that the bI1 lariat RNA can also catalyse successive deoxyribonucleotide polymerization reactions on exogenous substrate molecules. The basic mechanism of the reaction involved interacting cycles between an alternative version of partial reverse splicing (lariat charging) and canonical forward splicing (lariat discharging by exon ligation). With an overall chain growth in the 3'-->5' direction, the 5' exon RNAs (IBS1dN) were elongated by successive insertion of deoxyribonucleotides derived from single deoxyribonucleotide substitutions (dA, dG, dC or dT). All four deoxyribonucleotides were used as substrates, although with different efficiencies. Our findings extend the catalytic repertoire of group II intron RNAs not only by a novel DNA polymerization activity, but also by a DNA-DNA ligation capacity, supporting the idea that ribozymes might have been part of the first primordial polymerization machinery for both RNA and DNA. 相似文献
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Kararigas G Becher E Mahmoodzadeh S Knosalla C Hetzer R Regitz-Zagrosek V 《Biology of sex differences》2010,1(1):2-9
Background
Although circulating levels of sexual hormones in elderly men and women are low and quite similar, the adaptation of the elderly heart to stress differs between the sexes. We have hypothesized that the effects of sexual hormones in the heart may differ in men and women. Here, we assessed whether 17β-oestradiol regulates gene expression in the human heart in a sex-dependent manner. We selected the progesterone receptor as a well studied 17β-oestradiol target that may be pathologically linked to cardiac remodelling.Methods
In order to assess the ex vivo effects of 17β-oestradiol in intact human cardiac tissues, we developed a 24-h model for the culture of human atrial myocardium. We verified tissue viability after 24 h in culture with two standard assays to determine the degree of apoptosis and metabolic activity of cardiac tissues. Progesterone receptor mRNA and protein level were measured after 24-h treatment of tissues with 17β-oestradiol. Statistical analysis was performed by the Mann-Whitney U test and two-way ANOVA.Results
We established a tissue culture model that allows for the study of viable human cardiac tissue over a 24-h period. After 24 h, cultured cardiac tissues revealed low apoptosis, retained their metabolic activity and, therefore, remained viable. Treatment with 17β-oestradiol led to an induction of the progesterone receptor mRNA level in female (P = 0.001) but not in male tissues. Similarly, there was an increase in the level of progesterone receptor protein in female tissues (P = 0.03), while a decreasing trend was observed in male tissues (P = 0.079) exposed to 17β-oestradiol.Conclusions
Our novel finding may offer a molecular explanation for the sex-specific differences observed in cardiac remodelling. The culture model we established for human cardiac tissue will facilitate the study of cellular processes in health and disease and will be of use for pharmacological testing. 相似文献26.
The Ran GTPase as a marker of chromosome position in spindle formation and nuclear envelope assembly 总被引:1,自引:0,他引:1
The small GTPase Ran is a key regulator of nucleocytoplasmic transport during interphase. The asymmetric distribution of the GTP-bound form of Ran across the nuclear envelope--that is, large quantities in the nucleus compared with small quantities in the cytoplasm--determines the directionality of many nuclear transport processes. Recent findings that Ran also functions in spindle formation and nuclear envelope assembly during mitosis suggest that Ran has a general role in chromatin-centred processes. Ran functions in these events as a signal for chromosome position. 相似文献
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Cseh R Hetzer M Wolf K Kraus J Bringmann G Benz R 《European biophysics journal : EBJ》2000,29(3):172-183
The interaction of phloretin with single lipid bilayers on a spherical support and with multilamellar vesicles was studied
by differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR). The results indicated that phloretin interacts
with the lipid layer and changes its structural parameters. In DSC experiments, phloretin in its neutral form strongly decreased
the lipid phase transition temperature and slightly reduced the cooperativity of the phase transition within the lipid layer.
In NMR measurements, phloretin led to an increase of the transverse relaxation time constant but had no effect on the spin-lattice
relaxation time constant. The overall dipole moment of phloretin was experimentally determined and was found to be roughly
40% lower than has been published previously. This result suggested that the size of the dipole moment of phloretin does not
provide such a high contribution to the effect of phloretin on the dipole potential of monolayers and bilayers as has been
published previously. To understand the discrepancy between phloretin adsorption and dipole potential change, we performed
computational conformational analysis of phloretin in the gas phase. The results showed that a wide distribution of the dipole
moments of phloretin conformers exists, which mainly depends on the orientation of the OH moieties. The adsorption of phloretin
as determined from its binding to solid supported bilayers differed from the one determined from dipole potential measurements
on black lipid membranes. The difference between the phloretin dissociation constants of both types of experiments suggested
a change of its dipole moment normal to the membrane surface in a concentration-dependent manner, which was in agreement with
the results of the computational conformational analysis.
Received: 21 June 1999 / Revised version: 7 January 2000 / Accepted: 31 March 2000 相似文献
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Novel mutations in sarcomeric protein genes in dilated cardiomyopathy 总被引:11,自引:0,他引:11
Daehmlow S Erdmann J Knueppel T Gille C Froemmel C Hummel M Hetzer R Regitz-Zagrosek V 《Biochemical and biophysical research communications》2002,298(1):116-120
Mutations in sarcomeric protein genes have been reported to cause dilated cardiomyopathy (DCM). In order to detect novel mutations we screened the sarcomeric protein genes beta-myosin heavy chain (MYH7), myosin-binding protein C (MYBPC3), troponin T (TNNT2), and alpha-tropomyosin (TPM1) in 46 young patients with DCM. Mutation screening was done using single-strand conformation polymorphism (SSCP) analysis and DNA sequencing. The mutations in MYH7 were projected onto the protein data bank-structure (pdb) of myosin of striated muscle. In MYH7 two mutations (Ala223Thr and Ser642Leu) were found in two patients. Ser642Leu is part of the actin-myosin interface. Ala223Thr affects a buried residue near the ATP binding site. In MYBPC3 we found one missense mutation (Asn948Thr) in a male patient. None of the mutations were found in 88 healthy controls and in 136 patients with hypertrophic cardiomyopathy (HCM). Thus mutations in HCM causing genes are not rare in DCM and have potential for functional relevance. 相似文献