首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Effect of CpG methylation on Msp I.   总被引:13,自引:7,他引:13       下载免费PDF全文
The restriction enzyme Msp I is inhibited by the presence of a methyl moiety at the external cytosine of the sequence CCGG, but is generally unaffected by methylation at the internal cytosine. At specific subsets of this sequence such as the hexanucleotide CCGGCC, however, methylation of the internal cytosine strongly inhibits Msp I digestion, leading to artifacts in the interpretation of DNA methylation analyses. Our results show, for instance, that the CCGG site at the 5' end of the human gamma globin gene, which was thought to be methylated at both the internal and external cytosines, is actually methylated only at the internal CpG residue.  相似文献   

2.
Tropomyosin polymerization is inhibited by DNAse I, an endonuclease which also interacts with G-actin. A 1:4 molar ratio of DNAse I to adult chicken pectoralis muscle tropomyosin almost completely prevents the increased viscosity of tropomyosin under polymerizing ionic conditions. While G-actin binding to DNAse I inhibits the DNAse I hydrolysis of DNA, tropomyosin does not affect this enzymatic activity. G-actin-DNAse I interaction is also not altered by tropomyosin.  相似文献   

3.
Immune gamma-globulins containing antibodies to bovine DNAse I inhibit activities of bovine and mouse DNAse I both in vitro and in vivo. Bovine DNAse I was used as exogenous DNAse I in the in vivo studies and was injected to mice intraperitoneally in combination with gamma-globulins. The serous fluid of mice was used as a source of endogenous DNAse I. Both in in vitro and in vivo studies immune gamma-globulins caused a practically complete inhibition of bovine DNAse I activity, whereas the activity of mouse DNAse I (endogenous) was inhibited by 60-80%. Nonimmune gamma-globulins had no inhibitory effects whatsoever.  相似文献   

4.
A 250-fold purified ATP-dependent DNase from Bacillus cereus has been separated to DNA-dependent ATPase I and II and a DNase specific for single-stranded DNA (ssDNase) by means of high resolution of DEAE cellulose chromatography. Simultaneously with the separation of ATPase and ssDNase, a decrease in ATP-dependent DNase activity was observed. Complete separation resulted in the total loss of ATP-dependent DNase activity. Reconstitution of ATP-stimulated DNase activity was dependent on the ratio of the combined ATPase II and ssDNase.  相似文献   

5.
6.
It has been shown that pancreatic DNAase added to the nutritious medium caused the change in the nuclear DNA topology of asporogenic Candida tropicalis yeast. DNA conformative changes are due to the unwinding of supertwisted molecules as a result of single-strand ruptures formation which induce DNA synthesis acceleration, cell growth and division.  相似文献   

7.
An increase in the DNAase 1 activity in the serum and an increase in the DNAase inhibitor activity in the spleen in the development of virus Friend leukemia were demonstrated. Increased activity of the inhibitor in the spleen was also revealed after intravenous injection of exogenous DNAase 1 into mice. A potential role of serum DNAase 1 in the development of experimental leukemia is discussed.  相似文献   

8.
Rat liver chromatin activated by partial hepatectomy is more susceptible to the action of DNAse I than control chromatin isolated from intact liver. The study on the transfer of chromatin material to the acid-soluble fraction reveals a higher rate of activated chromatin degradation. Activated chromatin shows also an increased capacity for ethidium bromide (EB) binding as estimated from the isotherms of adsorption. The difference in EB binding between activated and control chromatin is abolished after DNAse I treatment. Conditions of mild digestion with DNAse I have been found under which the number of binding sites for EB per nucleotide decreases to almost the same level in activated and non-activated chromatin. The results suggest a preferential degradation of those DNA sequences in activated chromatin that are responsible for the increase in the ligand binding.  相似文献   

9.
The treatment in vitro of bone marrow cells in mice by phytohemagglutinin, concanavaline, or antilimphocytic globulin resulted in the suppression of exogenous hemopoietic colonies in the spleen of lethally irradiated (830r) syngenic recipients, whereas lipopolysaccharide, tuberculin, anti-theta serum or nati-gamma-globulin serum exerted no influence on the colony-forming function of hemopoietic stem cells. The morphological analysis of the ratio and cell composition of hemopoietic colonies has revealed no marked differences between the experimental and control groups. The suppression of hemopoietic stem cells by mitogens might be due both to their direct effect and indirect one, possibly, through a humoral factor.  相似文献   

10.
Aims: To evaluate individual and combined effects of temperature (4, 18 and 25°C), pH (7 and 10), ammonia (5 and 50 mg l?1) and exposure time (1, 2, 4 and 6 days) on the viability of Cryptosporidium parvum oocysts in water. Methods and Results: The viability of oocysts was evaluated using the fluorogenic vital dyes assay (4′,6‐diamidino‐2‐phenylindole and propidium iodide). All the factors analysed (temperature, pH, ammonia and exposure time) and their interaction were statistically significant (P < 0·005). Exposure of oocysts to pH 10 for 6 days at 25°C reduced oocyst viability from ~80% to 51%. Similarly, the exposure of C. parvum oocysts to 5 mg NH3 l?1 and 50 mg NH3 l?1 for 4 days reduced their viability from between ~80% to 41·5% and 14·8%, respectively. Conclusions: The interaction between pH, temperature and exposure time may have adverse effects on the survival of C. parvum oocysts in water. Low concentrations of ammonia, as commonly found in alga‐based wastewater systems, over a long period of time can produce high C. parvum oocyst inactivation rates. Significance and Impact of the Study: This study provides relevant data on the inactivation of C. parvum oocysts in alga‐based wastewater‐treatment systems in the northwest of Spain.  相似文献   

11.
An addition of pancreatic DNAse to the cultural medium is found to stimulate DNA synthesis and proliferation of Bacillus subtilis cells. Pancreatic DNAse induces a single-stranded disruption of Bac. subtilis DNA, which may act as a mechanism of DNA synthesis increase and of the culture growth acceleration.  相似文献   

12.
Chromosomal preparations were digested with different concentrations of DNAse I for various periods of time and then stained with Giemsa. It was found that this endonuclease rapidly modifies the structure of the chromosomes which then lose most of their stainability. However, small chromosomal segments corresponding to the nucleolar organizers (NORs) in man have been consistently observed. Although DNAse I treatment has permitted us to observe that some NORs are stained less intensely than others, comparisons with silver nitrate-stained NORs have shown a strict correspondence, in metaphase as well as in interphase. Chromosomal proteins seem responsible for this staining.  相似文献   

13.
The effect of pancreatic DNAase on the growth of Bacillus subtilis, the synthesis of DNA, RNA and protein in the cells was studied as a function of their physiological state. The cells were found to be sensitive to the action of DNAase at the end of the linear growth phase, which coincided with their transition into the competence state and with their ability to adsorb the enzyme on the cell surface.  相似文献   

14.
15.
We have used DNase I as a probe for structural changes in regions of chromatin containing highly acetylated histones. The enzyme preferentially digests regions of chromatin that are associated with rapidly or highly acetylated histones, suggesting that nucleosomes in these regions are in a more accessible conformation. This sensitivity to DNase I may be related to the same factors which cause the differential digestion of active genes.  相似文献   

16.
Analysis on DNA methylation of various tissues in chicken   总被引:2,自引:0,他引:2  
Xu Q  Zhang Y  Sun D  Wang Y  Yu Y 《Animal biotechnology》2007,18(4):231-241
  相似文献   

17.
The stimulating effect of DNAase 1 on Escherichia coli reproduction has been studied depending on the content of slowly growing cells in the inoculation culture in the phase of delayed growth. Three cell fractions of E. coli have been obtained using the stepwise separation of the population in terms of buoyant density in the phase of delayed growth. In contrast to fractions I and II the fraction III contains cells with delayed growth, permeable to exogenous DNAase 1 and sensitive to the action of this enzyme. The faster growth of bacterial cells has been shown to be caused by the direct ferment action on the slowly growing cells. The autometabolites and autolysates don't take part in this process.  相似文献   

18.
19.
Synthetic polyanion pyran (copolimer of divinyl ether and maleic anhydride) injected to mice increases the titre of antibody to sheep red blood cells as well as the activity of serum DNAase I and DNAase I splenic inhibitor. Simultaneously a growth of the spleen weight takes place. A possible role of the DNAase I inhibitor system in the mechanism of the adjuvant action of synthetic polyanion is discussed.  相似文献   

20.
After removal of histone H1 about 40% of DNA in chromatin acquires the sensitivity of naked DNA to DNAse I. Digestion of H1-depleted chromatin with DNAse I leads to a qualitative change in the digestion pattern, generating DNA fragments of approx. 200 b.p. and multiples, similar to those obtained with micrococcal nuclease. Both effects are reversed upon reconstitution of purified H1 to H1-depleted chromatin.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号