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31.
Nigel L. Brown Tapan K. Misra Joseph N. Winnie Annette Schmidt Michael Seiff Simon Silver 《Molecular & general genetics : MGG》1986,202(1):143-151
Summary The DNA sequences of the mercuric resistance determinants of plasmid R100 and transposon Tn501 distal to the gene (merA) coding for mercuric reductase have been determined. These 1.4 kilobase (kb) regions show 79% identity in their nucleotide sequence and in both sequences two common potential coding sequences have been identified. In R100, the end of the homologous sequence is disrupted by an 11.2 kb segment of DNA which encodes the sulfonamide and streptomycin resistance determinants of Tn21. This insert contains terminal inverted repeat sequences and is flanked by a 5 base pair (bp) direct repeat. The first of the common potential coding sequences is likely to be that of the merD gene. Induction experiments and mercury volatilization studies demonstrate an enhancing but non-essential role for these merA-distal coding sequences in mercury resistance and volatilization. The potential coding sequences have predicted codon usages similar to those found in other Tn501 and R100 mer genes. 相似文献
32.
Astrid G. Chapman Michael J. Halsey Geneen P. Hart Nigel P. Luff Brian S. Meldrum Bridget Wardley-Smith 《Journal of neurochemistry》1986,47(1):314-317
Regional amino acid concentrations were measured in rat brain fixed by microwave irradiation at three levels of elevated atmospheric pressure corresponding to different phases of the high-pressure neurological syndrome [20 atmospheres absolute (ATA), no clinical signs; 60 ATA, tremor; 85 ATA, severe tremor and myoclonic jerks]. No changes in amino acid content occurred at 20 or 60 ATA. At 85 ATA glutamine content increased in hippocampus, striatum, cerebellum, and substantia nigra, and gamma-aminobutyric acid content increased in hippocampus. It is suggested that enhanced glutamate release in various subcortical structures contributes to the myoclonic activity observed at 85 ATA. 相似文献
33.
The major sesquiterpenes in the foliage of Dacrydium cupressinum are α-longipinene, longifolene, longibornyl acetate, caryophyllene, caryophyllene oxide, humulene, α- and β-selinene, β- and δ-elemene, aromadendrene and the rare 9βH-caryophyllene. Sesquiterpene levels vary greatly from tree to tree. As this variation is largely independent of environmental factors, genetic control is proposed. Longifolene and α-longipinene levels are closely correlated, as are those of caryophyllene and humulene. The biosynthetic implications of these correlations are discussed. 相似文献
34.
A method is described which allows a large number of bacterial strains to be rapidly and easily screened for the presence of site-specific endonucleases. The method involves selective permeabilization of the bacterial cell and analysis of the exuded material. Type II restriction endonucleases from cyanobacteria and Gram-negative eubacteria have been detected and new enzymes have been found. The method should be widely applicable and easy to modify for use in genera other than those tested. Three-site-specific endonuclease activities, detected by this method in Aphanothece halophytica PCC 7412, were purified and their recognition and cleavage specificities were determined AhaI and AhaII recognise and cleave the same DNA sequences as CauII and AcyI respectively; the specificity of AhaIII (TTTAAA) has been reported previously (Whitehead and Brown, 1982, FEBS Letters 143:296–300).Abbreviations Brij-58
20 cetyl ether
- Pu
purine nucleoside
- Py
pyrimidine nucleoside 相似文献
35.
We have isolated adenovirus origins of DNA replication from both the right and left ends of the genome, which are functional on linear autonomously replicating mini-chromosomes. The mini-chromosomes contain two cloned inverted adenovirus termini and require non-defective adenovirus as a helper. Replicated molecules are covalently attached to protein, and DNA synthesis is initiated at the correct nucleotide even when the origins are not located at molecular ends. The activity of embedded origins leads to the generation of linear minichromosomes from circular or linear molecules. These observations therefore suggest that sequences within the adenovirus origin of replication position the protein priming event at the adenovirus terminus. Experiments investigating the regeneration of deleted viral inverted terminal repeat sequences show a sequence-independent requirement for inverted sequences in this process. This result strongly suggests that repair results from the formation of a panhandle structure by a displaced single strand. On the basis of these observations we propose a model for the generation of adenovirus mini-chromosomes from larger molecules. 相似文献
36.
37.
The cyanobacteria Anabaena variabilis and Nostoc CAN showed a biphasic pattern of 14CH3NH
3
+
uptake at external pH values of 7.0 and 9.0. The initial phase of uptake, which was independent of metabolism of 14CH3NH
3
+
, was attributed to uptake via a CH3NH
3
+
(NH
4
+
) transport system at pH 7.0 and probably to passive diffusion of uncharged CH3NH2 and trapping by protonation at pH 9.0. The second slower phase of uptake was attributed to metabolism of CH3NH
3
+
via glutamine synthetase to form -methylglutamine which accumulates. Anabaena cylindrica showed an initial rapid uptake at pH 7.0 and pH 9.0 but metabolism of 14CH3NH
3
+
was undetectable at pH 7.0 and was barely detectable at pH 9.0. Pretreatment of A. variabilis with l-methionine-d,l-sulphoximine to inactivate glutamine synthetase, inhibited the second phase of 14CH3NH
3
+
uptake at both pH 7.0 and pH 9.0 and the accumulation of -methylglutamine but had no effect on the first phase of uptake. Following transfer of A. variabilis to darkness the initial phase of 14CH3NH
3
+
uptake at pH 7.0 and 9.0 was unaffected but the subsequent metabolism via glutamine synthetase was inhibited.Abbreviations MSX
l-methionine-d,l-sulphoximine
- GS
glutamine synthetase 相似文献
38.
Howard R. Morris Karen E. Batley Nigel G. L. Harding Richard A. Bjur John G. Dann Rodney W. King 《The Biochemical journal》1974,137(2):409-411
An elastase digest of a protein of unknown structure, dihydrofolate reductase, was studied by mass spectrometry. This soluble digest contained a large number of small peptides in different yields, within the ideal molecular-weight range (200-1200) for mixture-analysis mass spectrometry. Sequences of the major component peptides in the digest are reported. 相似文献
39.
40.