Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q9UIJ5 (Rec)
 58,342 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have isolated a new mutant of Bacillus subtilis temperature sensitive in DNA replication; its properties are those of an initiation mutant. When liquid cultures are shifted to 48 degrees DNA replication is the first macromolecular synthesis that stops, but only after synthesis of the amount of DNA predicted for the completion of one replication round. When spores of the mutant are germinated and shifted to 48 degrees at subsequent times, one round of DNA replication is observed only when the shift occurs between 60 and 100 min; earlier shifts do not allow replication to start, later shifts allow more than one replication. The DNA replicated after a shift to high temperature is enriched in markers close to the terminus. The reinitiation of DNA replication stopped by the high temperature, takes place following a shift to a permissive temperature only if protein synthesis is allowed. Examination of DNA replication following toluene treatment shows that the elongation of DNA chains is not affected at the non-permissive temperature. This mutant is shown by PBS-1 mapping to correspond to a new gene denominated dna P, which is located between the thy A and fur A genes and is distinct from all the mapped dna and rec genes of Bacillus subtilis. The mutation confers to the cells also a deficiency in the ability to be transformed, to be transfected with SPP1 phage DNA, and to survive treatment with methyl-methane sulfonate. These deficiencies, observed at the permissive temperature, are no more temperature dependent than in the parental strain. The ability to perform homologous and heterologous transduction with PBS-1 phage and the sensitivity to ultraviolet radiation or mitomycin C are normal.
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PMID:A new mutant of Bacillus subtilis altered in the initiation of chromosome replication. 81 Jun 58

Mutations were induced in Neurospora which cause increased sensitivity to MMS (methyl methane-sulfonate) and other mutagens. Genetic analysis of such mus demonstrated that some of them defined new DNA repair genes (mus-21, and mus-27 to mus-30), while others represented new alleles in previously known genes. To characterize them further, and especially to identify rec- types which have not yet been found in this species, many MMS-sensitive strains were tested for cross-sensitivities to bleomycin (BLM) and to hydrogen peroxide (H2O2) to which some rec- of other species are hypersensitive. In Neurospora, many of the MMS-sensitive mutants were found to be cross-sensitive to BLM and frequently these were also hypersensitive to ionizing radiation. Bleomycin sensitivity was demonstrated for all alleles of 10 different genes, 4 of them new ones, with mus-27 being the most sensitive of the latter (resembling uvs-6; Koga and Schroeder, 1987, Mutation Res., 183, 139). In contrast, very few of the MMS-sensitive mutants were hypersensitive to H2O2 and, in general, results of H2O2 tests were variable and differences between strains small. However, consistent deviations from wild type were observed in a few cases (most clearly for mus-9 and mus-11) when results from treatments of germinating conidia were compared with those of non-growing ones.
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PMID:Sensitivity to bleomycin and hydrogen peroxide of DNA repair-defective mutants in Neurospora crassa. 246 86

The medium in which Rec(+) strains of Escherichia coli K-12 are grown affected their sensitivity to treatment with methyl methane sulfonate (MMS). Rec(+) cells grown to the stationary phase in glucose-enriched nutrient broth (GNB) were more resistant to MMS than cells grown in nutrient broth (NB). The repair of MMS-induced breaks (or alkali-labile bonds) in the deoxyribonucleic acid (DNA) from E. coli K-12 strains AB1157, AB1886 uvrA6, and SR111 recA13 recB21 grown in GNB and NB media was examined by means of alkaline sucrose gradient centrifugation. It appeared that essentially all of the repair of breaks that occurred, as evidenced by an increase in "molecular weight," took place within 10 min after treatment with MMS under our conditions. Cell survival was highest in cells for which the size of the DNA after the post-treatment incubation was the largest. The largest DNA after post-treatment incubation was found in Rec(+) cells grown in GNB medium. The results suggest that these cells may have an enhanced capacity for repairing breaks in DNA.
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PMID:Physiological modifications in the production and repair of methyl methane sulfonate-induced breaks in the deoxyribonucleic acid of Escherichia coli K-12. 434 30

A collection of 16 isogenic recombination-deficient strains of Bacillus subtilis isolated on the basis of sensitivity to methyl methane sulfonate (MMS) or mitomycin C (MC) were characterized phenotypically. All were found to be somewhat sensitive to ultraviolet irradiation, MC, and MMS. The mutants were all blocked in "late" steps in the transformation process and were provisionally grouped into four categories on the basis of the various properties examined. Class I mutants were deficient in transformation and heterologous transduction with phage PBS1 but were transducible with homologous donors at nearly the wild-type frequency. They were blocked in donor-recipient complex (DRC) formation but formed essentially normal amounts of double-strand fragments (DSF) and single-strand fragments (SSF). The class IIa strain was deficient in transformation and PBS1 transduction, and formed DRC which was normal by all available physical and biological criteria. Class IIb mutants were deficient in transformation and PBS1 transduction, and failed to form DRC. They did produce DSF and SSF. Class III mutants were deficient in transformation, were normal in PBS1 transduction, and formed DRC which was physically indistinguishable from that of the Rec(+) parent although with slightly lowered donor-type transforming activity. Class IV strains were deficient in PBS1 transduction but were transformed at nearly the wild-type efficiency. None of the mutant strains was deficient in the adenosine triphosphate-dependent deoxyribonuclease.
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PMID:Fate of transforming deoxyribonucleic acid after uptake by competent Bacillus subtilis: phenotypic characterization of radiation-sensitive recombination-deficient mutants. 434 31

The RAD51 gene is a eukaryotic homolog of rec A, a critical component in homologous recombination and DNA repair pathways in Escherichia coli . We have cloned the RAD51 homolog from Tetrahymena thermophila , a ciliated protozoan. Tetrahymena thermophila RAD51 encodes a 36.3 kDa protein whose amino acid sequence is highly similar to representative Rad51 homologs from other eukaryotic taxa. Recombinant Rad51 protein was purified to near homogeneity following overproduction in a bacterial expression system. The purified protein binds to both single- and double-stranded DNA, possesses a DNA-dependent ATPase activity and promotes intermolecular ligation of linearized plasmid DNA. While steady-state levels of Rad51 mRNA are low in normally growing cells, treatment with UV light resulted in a >100-fold increase in mRNA levels. This increase in mRNA was time dependent, but relatively independent of UV dose over a range of 1400-5200 J/m2. Western blot analysis confirmed that Rad51 protein levels increase upon UV irradiation. Exposure to the alkylating agent methyl methane sulfonate also resulted in substantially elevated Rad51 protein levels in treated cells, with pronounced localization in the macronucleus. These data are consistent with the hypothesis that ciliates such as T.thermophila utilize a Rad51-dependent pathway to repair damaged DNA.
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PMID:Identification and characterization of the RAD51 gene from the ciliate Tetrahymena thermophila. 962 14

In situ time-resolved Fourier transform infrared (FTIR) and microprobe Raman spectroscopies were used to characterize the reaction mechanisms of the partial oxidation of methane to syngas over SiO(2)- and gamma-Al(2)O(3)-supported rhodium and ruthenium catalysts. The interaction of both pure methane and a methane/oxygen mixture at a stoichiometric feed ratio with an oxygen-rich catalyst surface led to the formation of CO2 and H(2)O as the primary products. For the H(2)-pretreated samples, the reaction mechanisms with the catalysts differ. Only Rh/SiO(2) is capable of catalyzing the direct oxidation of methane to syngas, while syngas formation over Rh/gamma-Al(2)O(3), Ru/SiO(2), and Ru/gamma-Al(2)O(3) can be achieved mainly via a combustion-reforming scheme. The significant difference in the mechanisms for partial oxidation of methane to syngas over the catalysts can be correlated to the differences in the concentration of oxygen species (O(2-)) on the catalyst surface during the reaction, mainly due to the difference in the nature of the metals and supports.
Chem Rec 2002
PMID:Mechanistic study of partial oxidation of methane to syngas using in situ time-resolved FTIR and microprobe Raman spectroscopies. 1200 Dec 9

We have isolated recombination deficient mutants of Bacillus subtilis on the basis of their sensitivity to methyl-methane-sulfonate or ultraviolet light, or of their inability to be transformed on solid medium. We have analyzed the mutants for several recombination and repair properties; we have grouped them in 5 classes on the basis of their phenotype and tested them for the activity of several enzymes acting on DNA, ie. DNA polymerase, polynucleotide ligase, ATP dependent DNase, and a DNase acting on single-stranded DNA. One mutant was found reduced in the latter DNase. Some of the mutants have been mapped, and they correspond to three different genes denominated rec D, rec F and rec G. All the recombination deficient mutants of B. subtilis described in the literature have been grouped in 7 classes; the mutations belong to 13 (and possibly 15) different genes distributed along the map. A coherent nomenclature and the criteria for a standard study of the rec mutants are proposed.
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PMID:Genetic and enzymic studies on the recombination process in Bacillus subtilis. 1609 63

Four horses were randomly fed a diet containing rolled, micronised or extruded barley; the barley intake was adjusted to supply 2 g starch/kg bodyweight per day. During a 10-day acclimatisation period the horses were also fed 1 kg grass hay/100 kg bodyweight per day. Samples of blood and breath were collected at the end of each period after the test meal of barley had been fed after a 12-hour overnight fast. The glycaemic and insulinaemic responses of the horses were measured as an indication of the pre-caecal digestibility of starch, and postprandial breath hydrogen and methane were measured to detect microbial fermentation of starch. The highest peak serum glucose and serum insulin concentrations were observed after feeding the extruded barley, lower concentrations were observed after feeding the micronised barley and the lowest concentrations were observed after feeding the rolled barley. Breath hydrogen increased within four hours of feeding all the barley diets, and the mean (sd) peak hydrogen concentrations were 98.3 (55.2) ppm for rolled barley, 59.3 (31.5) ppm for micronised barley and 96.1 (51.9) ppm for extruded barley. There were wide variations within individual horses but these concentrations were not significantly different. Breath methane concentrations were very variable and, although there were no significant differences, there was a trend for higher methane concentrations after the feeding of rolled barley.
Vet Rec 2008 May 24
PMID:Effects of processing barley on its digestion by horses. 1850 68

Theoretical and computational methods are powerful in studying transition metal complexes. Our theoretical studies of C-H sigma-bond activation of benzene by Pd(II)-formate complex and that of methane by Ti(IV)-imido complex successfully disclosed that these reactions are understood to undergo heterolytic sigma-bond activation and the driving force is the formation of strong O-H and N-H bonds in the former and the latter, respectively. Orbital interactions are considerably different from those of sigma-bond activation by oxidative addition. The transmetallation, which is a key process in the cross-coupling reaction, is understood to be heterolytic sigma-bond activation. Our theoretical study clarified how to accelerate this transmetallation. Also, we wish to discuss weak points in theoretical and computational studies of large systems including transition metal elements, such as the necessity to incorporate solvation effect and to present quantitatively correct numerical results. The importance of solvation effects is discussed in the oxidative addition of methyliodide to Pt(II) complex which occurs in a way similar to an S(N)2 substitution. To apply the CCSD(T) (coupled cluster singles and doubles with perturbative triples correction) method, which is the gold standard of electronic structure theory, to large system, we need to reduce the size of the system by employing a small model. But, such modeling induces neglects of electronic and steric effects of substituents which are replaced in the small model. Frontier-orbital-consistent quantum-capping potential (FOC-QCP) was recently proposed by our group to incorporate the electronic effects of the substituents neglected in the modeling. The CCSD(T) calculation with the FOC-QCP was successfully applied to large systems including transition metal elements.
Chem Rec 2010 Mar
PMID:Theoretical and computational studies of organometallic reactions: successful or not? 2019 36

Porous metal-organic frameworks (MOFs) are a novel family of physisorptive materials exhibiting great potential for methane storage applications. Several MOF compounds have been reported to exhibit high methane uptake at room temperature and modest pressure, with a few even surpassing the target for material-based, adsorbed methane storage set by U.S. Department of Energy. Here we briefly review the rapid research progress in recent years on methane storage in MOFs and highlight the current record holders. We also discuss the current understanding of the methane storage mechanism in these fascinating materials and outline the future directions in this field.
Chem Rec 2010 Jun
PMID:Methane storage in porous metal-organic frameworks: current records and future perspectives. 2050 45


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