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921.
Margit M.K. Nass 《Gene》1983,21(3):249-255
A precise physical map, containing the structurally and operationally defined D-loop origin, terminal region, and direction of heavy-strand replication, has been constructed for mitochondrial DNA (mtDNA) from ovary (CHO-KI) and lung cells of Chinese hamster (Cricetulus griseus 2 N = 22), and compared with our previously established genome coordinates for mtDNA from Syrian hamster ( Mesocricetus auratus 2 N = 44). All four HpaI sites in Cricetulus are conserved in Mesocricetus (8 sites). Extensive variation exists for hexanucleotides cleaved by EcoRI HindIII PstI. KpnI and BamHI. Sequence divergence between Chinese and Syrian hamster mtDNAs, as reflected from analysis of the mapped recognition sites for these six endonucleases, is estimated as 5–9% base substitutions. mtDNAs from both hamster and several other mammalian species contain a commonly conserved HpaI site in the region of light strand initiation. 相似文献
922.
Francis L. Marcrina R.Paul Evans Janet Ash Tobian Donna L. Hartley Don B. Clewell Kevin R. Jones 《Gene》1983,25(1):145-150
A novel plasmid vector that is able to replicate both in Escherichia coli and in Streptococcus sanguis is described. This 9.2-kb plasmid, designated pVA856, carries Cmr, Tcr and Emr determinants that are expressed in E. coli. Only the Emr determinant is expressed in S. sanguis. Both the Cmr and the Tcr of pVA856 may be insertionally inactivated. This plasmid affords several different cleavage-ligation strategies for cloning in E. coli followed by subsequent introduction of chimeras in to S. sanguis. In addition, we have modified a previously described E. coli-S. sanguis shuttle plasmid [pVA838; Macrina et al., Gene 19 (1982) 345–353], so that it is unable to replicate in S. sanguis. The utility of such a plasmid for cloning and selecting sequences enabling autonomous replication in S. sanguis is demonstrated. 相似文献
923.
Stable integration of foreign DNA into the chromosome of the cyanobacterium Synechococcus R2 总被引:28,自引:0,他引:28
The blue-green alga, Synechococcus R2, is transformed to antibiotic resistance by chimeric DNA molecules consisting of Synechococcus R2 chromosomal DNA linked to antibiotic-resistance genes from Escherichia coli. Chimeric DNA integrates into the Synechococcus R2 chromosome by homologous recombination. The efficiency of transformation, as well as the stability of integrated foreign DNA, depends on the position of the foreign genes relative to Synechococcus R2 DNA in the chimeric molecule. When the Synechococcus R2 DNA fragment is interrupted by foreign DNA, integration occurs through replacement of chromosomal DNA by homologous chimeric DNA containing the foreign insert; transformation is efficient and the foreign gene is stable. Mutagenesis in some cases attends integration, depending on the site of insertion. Foreign DNA linked to the ends of Synechococcus R2 DNA in a circular molecule, however, integrates less efficiently. Integration results in duplicate copies of Synechococcus R2 DNA flanking the foreign gene and the foreign DNA is unstable. Transformation in Synechococcus R2 can be exploited to modify precisely and extensively the genome of this photosynthetic microorganism. 相似文献
924.
D Christophe V Pohl B Van Heuverswijn G De Martynoff H Brocas J E Dumont J L Pasteels G Vassart 《Biochemical and biophysical research communications》1982,105(3):1166-1175
A rat genomic library was screened for thyroglobulin gene clones with recombinant plasmids containing rat thyroglobulin complementary DNA inserts. Two identical recombinant phages were found. A map of the inserted genomic sequence established by restriction and blotting experiments, and electronic microscopy revealed that this fraction of the gene was extensively split. Exons were ≤ 200 base pair long while the introns represented 93% of the insert. A fragment subcloned in plasmid pBR 322 was shown to contain repetitive sequences when used in Southern blot experiments with rat total genomic DNA. 相似文献
925.
J P Albertini A Garnier-Suillerot L Tosi 《Biochemical and biophysical research communications》1982,104(2):557-563
When Fe(II) is added to a bleomycin. DNA mixture in the presence of air a long-lived EPR silent species (I′) is formed; the circular dichroism and absorption spectra of which have been characterized. This complex slowly decays yielding a ferric complex (III′) analogous to the well known low spin Fe(III). BLM species. 相似文献
926.
W.James Nelson Constantin E. Vorgias Peter Traub 《Biochemical and biophysical research communications》1982,106(4):1141-1147
A new method is described for the purification of the intermediate filament protein vimentin from Ehrlich ascites tumor cells using single-stranded DNA-cellulose affinity chromatography. The procedure is rapid and allows the large scale isolation of the protein. Partial characterization of vimentin shows that it has a molecular weight of 58000 and an apparent pI of 5.3. It can be degraded by the vimentin-specific, Ca2+-activated proteinase which results in the production of a characteristic set of degradation products. The vimentin also cross-reacts with the intermediate filament protein monoclonal antibody, α-IFA. 相似文献
927.
Induction and repair of DNA strand breaks in cultured human fibroblasts exposed to various phenols and dihydrodiols of benzo[a]pyrene 总被引:1,自引:0,他引:1
Cultured human fibroblasts from healthy donors were incubated for 30 min with nine different benzo[a]pyrene (BP) derivatives in the presence or absence of liver microsomes from 3-methylcholanthrene treated rats. The induction and repair of DNA strand breaks were analysed by alkaline unwinding and separation of double and single stranded DNA (SS-DNA) by hydroxylapatite chromatography immediately after the incubation or at various times after the treatment. In the absence of microsomes DNA stand breaks were detected in fibroblasts exposed to 30 microM of each of the six BP phenols (1-, 2-, 3-, 7-, 9- or 11-OH-BP) and the three BP dihydrodiols (BP-4,5-, BP-7,8- or BP-9,10-dihydrodiol). After removal of the BP derivatives from the medium the DNA strand breaks disappeared within 24 h. alpha-Naphthoflavone (alpha-NF) caused a decrease in the induction of strand breaks by 1-, 3- and 9-OH-BP but did not affect the induction of strand breaks in cells exposed to BP-7,8-dihydrodiol. In the presence of microsomes DNA strand breaks were found after exposure to 30 microM of each of the six BP phenols (1-, 2-, 3-, 7-, 9- or 11-OH-BP), as well as BP-7,8- and 9,10-dihydrodiol. In contrast BP-4,5-dihydrodiol did not induce strand breaks under these conditions. The induction of strand breaks by BP-7,8-dihydrodiol was enhanced in the presence of cytosine-1-beta-D-arabinofuranoside (AraC). In all cases the DNA strand breaks had disappeared 24 h after removal of the BP derivatives and microsomes except after treatment with BP-7,8-dihydrodiol. 相似文献
928.
Metabolism and activation of benzo[a]pyrene by mouse and rat skin in short-term organ culture and in vivo 总被引:1,自引:0,他引:1
The metabolic activation of BP was examined in mouse and rat skin in vivo and in short-term organ culture. In mouse skin, larger quantities of ether- and water-soluble metabolites were formed and more BP became bound covalently to DNA and protein than in rat skin. Qualitative differences in the formation of dihydrodiol metabolites and of BP-deoxyribonucleoside adducts between mouse and rat skin were also observed. Organ culture techniques may not provide a true model of metabolic activation in vivo because it was found that the covalent binding of BP to DNA and protein was reduced in skin maintained in culture despite an accumulation of dihydrodiol and other ether-soluble metabolites. In addition, the proportions of the syn- and anti-isomers of BP-7,8-diol 9,10-oxide involved in the formation of adducts with deoxyguanosine differed between skin treated in organ culture and in vivo. 相似文献
929.
930.
Constantin C. Chipev Miglena I. Angelova 《International journal of biological macromolecules》1983,5(4):252-253
The denaturation of short (145 base pairs) and long (about 8000 base pairs) DNA moelucules has been studied by adiabitic differential microcalorimetry in solutions with different NaCl content. It is found that the enthalpy of denaturation of short DNA is more sensitive to changes in Tm than that of long DNA. A comparison with other data is also given. 相似文献