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排序方式: 共有190条查询结果,搜索用时 15 毫秒
1.
Bisulfite reversibly inhibits the growth of a variety of microorganisms and has been used as a preservative in foods and beverages for that reason. We have now measured macromolecule synthesis in Escherichia coli K12 after bisulfite treatment. RNA synthesis, the synthesis of total protein, and of an inducible enzyme, beta-galactosidase, stopped almost immediately upon addition of 2 mM (or higher concentrations) of bisulfite. These functions resumed after a lag whose duration depended on the concentration of bisulfite added. The synthesis of DNA was slowed upon bisulfite addition, but did not stop entirely. The inhibition of RNA synthesis by bisulfite took place in both stringent and relaxed strains of E. coli and was not relieved upon addition of chloramphenicol. Stringent control was therefore not involved in this effect. No effect on protein synthesis was observed in the cell-free system of E. coli (using poly(U) or MS2 RNA as messenger) at bisulfite concentrations up to 10 mM. Protein synthesis inhibition in vivo was apparently not due to a reaction of bisulfite with a component of this system. In additional experiments, RNA polymerase was not impaired by bisulfite, and the growth inhibition effect was shown to proceed in the presence of inhibitors of free radical chain reactions. 相似文献
2.
Replication variants of the inactive X chromosome were investigated in lymphocytes from six donors by means of terminal BrdU or thymidine incorporation. There were interindividual differences in the incidence of particular variants. In endoreduplicated and tetraploid cells both allocyclic X chromosomes showed the same replication sequence. The Xp22 band of the allocyclic X chromosome seemed to replicate later than the homologous material in some cells. Initiation time of DNA synthesis within the inactive X chromosome was found to be stable; termination time, however, varied greatly relative to the other chromosomes. Early completion of replication within the heterochromatic X chromosome could be demonstrated preferentially for the Xq25–27 terminal sequence, but other variants expressed the phenomenon also. A variable replication rate of the inactive X chromosome is believed to be responsible for its asynchronous, independent replication. The biological significance of the phenomenon is discussed with respect to cell differentiation. 相似文献
3.
Behrens Jane W. Ryberg Marie P. Einberg Heli Eschbaum Redik Florin Ann-Britt Grygiel Wlodzimierz Herrmann Jens Peter Huwer Bastian Hssy Karin Knospina Elina Nomaa Kristiina Oesterwind Daniel Polte Patrick Smoliski Szymon Ustups Didzis van Deurs Mikael Ojaveer Henn 《Biological invasions》2022,24(2):527-541
Biological Invasions - Native to the Ponto-Caspian region, the benthic round goby (Neogobius melanostomus) has invaded several European inland waterbodies as well as the North American Great Lakes... 相似文献
4.
The specificity of formation of phage f2 RNA-protein complexes was studied. Complex I contains up to 8 mol of coat protein per 1 mol of RNA. Its formation proceeds equally well in medium (i) without magnesium ions, (ii) containing magnesium ions, (iii) containing 4 mM EDTA, and (iv) at temperatures from 0 to 45 C. Complex II contains up to 200 mol of coat protein per 1 mol of RNA. Its formation is inhibited by the presence of magnesium ions in medium. Formaldehyde- or methoxyamine-treated f2 RNA in which only exposed bases were modified showed a normal pattern of complex II formation, whereas formation of complex I was inhibited or abolished. We conclude that complex I formation involves the interaction between coat protein and specific region of exposed bases in RNA. A possible site of attachment of coat protein is discussed. 相似文献
5.
Stanislaw Fedyk Wlodzimierz Chtnicki Agata Banaszek 《Evolution; international journal of organic evolution》1991,45(6):1384-1392
Two parapatric chromosomal races of the common shrew (Sorex araneus) in Poland differ in their complement of metacentric arm combinations: hk, io, gr, nm (race IV), and hi, ko, gm, np (race II). In hybrids, these eight race-diagnostic metacentrics form two randomly segregating complexes. The first complex (C1) occurs in the form of a ring configuration ok/kh/hi/io, or a chain o/ok/kh/hi/i (when there is Robertsonian polymorphism of the element io). The second complex (C2) always takes the form of a six-element chain configuration r/rg/gm/mn/np/p. The C2 complex may be shortened to five or even four elements, when acrocentrics g, m and n are present. In the contact zone we found shrews of pure races (race II or IV), as well as hybrids with C1 or C2 complexes, and recombinants hi, ko, gr, nm. Complex heterozygotes are likely to suffer reduced fertility due to malsegregation at meiosis. However, the C1 hybrids with ring configurations occur with a high frequency throughout the contact zone. This suggest that their fitness is only slightly lowered relative to pure race individuals, in contrast to the hybrids with C1 or C2 chain configurations, which presumably have a more heavily reduced fertility. On the other hand, at the center of the zone there is a high proportion of recombinants, which, being chromosomal homozygotes, should display normal meiotic segregation. Furthermore, the high frequencies of recombinants within the contact zone should facilitate gene flow between the races. The occurrence of recombinants plays a similar role as the appearance of the maximum frequencies of acrocentric homozygotes described in several contact zones of S. araneus. 相似文献
6.
Joanna Suliburska Pawel Bogdanski Ewa Gajewska Grazyna Kalmus Magdalena Sobieska Wlodzimierz Samborski 《Journal of physiology and biochemistry》2013,69(4):847-853
Some data indicate a potential relationship between insulin resistance level and the concentration of osteoprotegerin (OPG) in the body. There have been few studies concerning OPG level and its relationship with insulin resistance and body composition in young people. The aim of this study was to assess serum osteoprotegerin concentration in obese adolescents, and to evaluate its potential association with insulin resistance. Seventy-eight obese adolescents and 20 healthy volunteers aged 12–18 years were recruited in the study. Selected anthropometrical measurements and blood biochemical analyses were performed. Insulin resistance in the participants was evaluated according to the homeostasis model assessment-insulin resistance (HOMA-IR) protocol. Level of OPG was assessed in serum. Obese subjects had significantly higher HOMA-IR indices and OPG levels in serum than the control group. A significant positive correlation between OPG and insulin resistance was found. It was observed that high concentrations of osteoprotegerin are associated with insulin resistance in obese adolescents. 相似文献
7.
Ordered state of poly-uridylic acid above room temperature 总被引:4,自引:0,他引:4
W Szer 《Journal of molecular biology》1966,16(2):585-587
8.
9.
One of the biggest surprises at the beginning of the 'post-genome era' was the discovery of numerous genes encoding microRNAs. They were found in genomes of such diverse organisms as Caenorhabditis elegans, Drosophila melanogaster, Arabidopsis thaliana, and Homo sapiens which implies their important role in multicellular life evolution. The number of microRNA genes is estimated to be nearly 1% of that of protein-coding genes. Their products, tiny RNAs, are thought to regulate gene expression during development, organogenesis, and very likely during many other processes, by hybridizing to their target mRNAs. The cellular functions of mRNAs that are regulated by microRNAs are only beginning to be revealed, and details of this regulation mechanism are still poorly understood. In this article we discuss the possible mechanisms of microRNA biogenesis with special emphasis on their structural aspects. We have focused on the factors and effects that may be responsible for the existing length differences between different microRNAs, and for the observed length heterogeneity within some individual microRNA species. 相似文献
10.
Structural determinants of BRCA1 translational regulation 总被引:4,自引:0,他引:4