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991.
Mitochondrial DNA (mtDNA) from two breeds of cattle, viz., [Hariana (Bos indicus), Holstein (Bos taurus)] and Indian water buffalo (Bubalis bubalus), was analyzed using 13 restriction endonucleases which recognized an average of about 40 six-base sites. Polymorphism among
cattle was detected with six of these enzymes. The two Holstein differed at six sites, whereas the Hariana breed (Bos indicus) did not show any site polymorphism. Surprisingly, the Hariana type differed by only one site from one of the Holstein types.
The total size of buffalo mtDNA was estimated to be 16.4 kb. Polymorphism within the Murrah buffalo breed was observed with
respect to aBglI site. Scarcely any of the restriction fragments of buffalo mtDNA matched those of cattle mtDNA. 相似文献
992.
993.
Claude Nicolau Claude Sene 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1982,721(2):185-190
The pBR322 plasmid containing the sequence encoding β-lactamase, the enzyme conferring resistance to ampicillin, was encapsulated in liposomes of different phospholipid composition and incubated with synchronized cells. In mitotic cells as compared to cells synchronized in G1, twice as many exogeneous DNA molecules were found associated with the cell nuclear DNA, when fluid, neutral liposomes were used. These liposomes are taken up by the cells mainly via endocytosis. When fluid, negatively charged liposomes were used as carriers about the same number of exogeneous DNA molecules were found associated with the nuclear DNA both in mitotic and in G1-synchronized cells. The efficiency for gene transfer of liposomes entering the cells by different mechanisms was further studied and expressed both by the fraction of the radioactive plasmid associated with the nuclear DNA and by the level of the β-lactamase activity detected in the transfected cells. It appears that liposomes entering the cells mainly via an energy-dependent mechanism are more efficient for this type of DNA transfer. 相似文献
994.
M.J. Edwards W.K. Kaufmann 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1982,721(2):223-225
Replicative DNA synthesis in normal human fibroblasts was inhibited by 50% when they were X-irradiated (8 Gy) and made permeable 30 min later, whereas only a slight inhibition (20%) was observed in similarly treated ataxia-telangiectasia cells. Treatment of irradiated normal cells with caffeine (2 mM) before permeabilization reversed the inhibitory effects of X-rays, buf caffeine had no effect on DNA synthesis in permeable ataxia-telangiectasia cells. Diadenosine tetraphosphate (0.1 mM) did not affect DNA synthesis in permeable normal fibroblasts. 相似文献
995.
Margaret D. Mamet-Bratley Barbara Karska-Wysocki 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1982,698(1):29-34
Purified T7 phage, treated with methyl methanesulfonate, was assayed on four Escherichia coli K12 host cells: (1) AB1157, wild-type; (2) PK432-1, lacking 3-methyladenine-DNA glycosylase (tag); (3) NH5016, lacking apurinic endonuclease VI (xthA); (4) p3478, lacking DNA polymerase I (polA), the latter three strains being deficient in enzymes of the base excision repair pathway. For inactivation measured immediately after alkylation, phage survival was lowest on strains PK432-1 and p3478; for delayed inactivation, measured after partial depurination of alkylated phage, survival was much lower on strain p3478 than on PK432-1. These results demonstrate the important role played by 3-methyladenine-DNA glycosylase in the survival of methylated T7 phage. Quantitative analysis of the data, using the results of Verly et al. (Verly, W.G., Crine, P., Bannon, P. and Forget, A. (1974) Biochim. Biophys. Acta 349, 204–213) to correlate the dose with the number of methyl groups introduced into phage DNA, revealed that 5–10 3-methyladenine residues per T7 DNA constituted an inactivation hit for the tag mutant. Thus, 3-methyladenine may be as toxic a lesion as an apurinic site. 相似文献
996.
A novel polycationic ionen was synthesized and fractionated on carboxymethyl-Sephadex using a salt gradient in 7M urea. A
series of oligomers of discrete length were characterised by ultraviolet spectra. The ultraviolet spectra of oligomers revealed
a new band centred at 232.5 nm which was probably due to exciton splitting. Thermal denaturation studies indicated both stabilization
of the helix conformation and a higher degree of cooperativity in the melting of DNA (oligomers)n complex as compared to native
calf thymus DNA. Ionen oligomers exhibited large extrinsic Cotton effect at 232.5 nm which could be attributed to exciton
interaction. 相似文献
997.
The effect of early postnatal undernutrition and subsequent rehabilitation on wet weight, DNA, RNA, protein and the activities
of acid and alkaline DNases in the cerebellar region of rat brain was studied. The cerebellar region was found to be affected
significantly during early undernutrition. Further, earlier the initiation of nutritional rehabilitation the better was the
recovery and in some cases timely nutritional rehabilitation resulted in better than normal biochemical composition of the
brain. The specific activities of acid and alkaline DNases were not affected by early undernutrition. However, the total activities
of these enzymes were significantly low in undernourished rats (R115 and R21) Rehabilitation of these deprived groups upto 150 days resulted in higher amounts of these enzymes as compared to those of
age-matched controls. It is concluded that the two DNases, are synthesized in a preferential manner during rehabilitation,
It is further concluded that cerebellar region, in terms of development schedule and response to imposed calorie restriction,
is intermediary between grey and white matter regions. 相似文献
998.
Approximately 43–60% of the total genome in bovine, goat and sheep consisted of interspersed repeated and single copy DNA
sequences. Most of the interspersed repeated DNA sequences were 1500–2400 nucleotide pair long while a minor portion was more
than 4000 nucleotide pair long in goat and sheep and 3200 nucleotide pair long in bovine. About 1/3rd of single copy sequence
were interspersed and their length was in the range of 1000–1500 nucleotide pairs. 相似文献
999.
Summary The intratesticular excurrent duct system of the bull is composed of rete testis, tubuli recti, and the terminal segment of the seminiferous tubules. Each terminal segment is surrounded by a vascular plexus and may be subdivided into a transitional region, middle portion, and terminal plug. The modified supporting cells of the middle portion and the terminal plug no longer display the typical Sertoli-Sertoli junctions seen in the transitional region and the seminiferous tubule proper. In the region of the terminal plug a distinct central lumen is generally not observed: spermatozoa and tubular fluid must pass through an intricate system of communicating clefts between the apices of the closely attached modified supporting cells. Vacuoles in the supranuclear region of the cells in the middle portion indicate strong transepithelial fluid transport. In analogy to the epithelium of rete testis and tubuli recti, the supporting cells of the terminal segment are capable of phagocytosing spermatozoa. The vascular plexus investing the terminal segment serves a dual purpose: it is a regulatory device for fluid and sperm transport, as well as an area of increased diapedesis for white blood cells.Supported by a grant from the Deutsche Forschungsgemeinschaft 相似文献
1000.
The effect of gyrase inhibitors and cyclic AMP on induction and glucose repression of the 6-hydroxy-nicotine oxidases in Arthrobacter oxidans 总被引:1,自引:0,他引:1
The induction by d,l-nicotine of the enantiozymes 6-hydroxy-L-nicotine oxidase and 6-hydroxy-D-nicotine oxidase in Archrobacter oxidans was differently affected by the inhibitors of Escherichia coli gyrase, novobiocin and nalidixic acid. These compounds inhibited 6-hydroxy-L-nicotine oxidase induction slightly, but led to an increase in the level of 6-hydroxy-D-nicotine oxidase activity. Furthermore, the specific repression by glucose of 6-hydroxy-D-nicotine oxidase synthesis was not abolished by the addition of cAMP but by that of novobiocin.Abbreviations 6-HDNO
6-hydroxy-D-nicotine oxidase
- 6-HLNO
6-hydroxy-L-nicotine oxidase
- cAMP
cyclic 3,5-adenosine monophosphate
- Enzymes
Adenylate cyclase
- ATP
pyrophosphate-lyase (cyclizing) (EC 4.6.1.1)
- cAMP-phosphodiesterase
3:5-cyclic-nucleotide 5-nucleotido-hydrolase (EC 3.1.4.17)
- DNA gyrase
DNA topoisomerase II (EC 5.99)
- DNA polymerase
deoxynucleosidetriphosphate: DNA desoxynucleotidyl-transferase (EC 2.7.7.7)
- 6-hydroxy-L-nicotine oxidase
6-hydroxy-L-nicotine: oxygen oxidoreductase (EC 1.5.3.5)
- 6-hydroxy-D-nicotine oxidase
6-hydroxy-D-nicotine: oxygen oxidoreductase (EC 1.5.3.6)
- -lactamase
penicillin amido--lactamhydrolase (EC 3.5.2.6)
- nicotine dehydrogenase
nicotine: (acceptor)6-oxidoreductase (hydroxylating) (EC 1.5.99.4) 相似文献