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31.
David I. Dunstan Debbie P. Lashta Susan I. Kikcio Trevor A. Thorpe 《In vitro cellular & developmental biology. Plant》1992,28(1):33-38
Summary The effects of sucrose concentration, addition of ammonium nitrate, and exposure to N6-benzyl-adenine (BA) on multiplication potential with shoots derived from shoot cultures of 17- to 20-yr-old Douglas fir trees
[Pseudotsuga menziesii (Mirb.) Franco] were compared. Each of these conditions, when compared independently, affected recurrent shoot multiplication
and influenced shoot development, as measured by the abundance of shoot apices. Sucrose concentration was influential, the
use of 25 g · liter−1 providing twice the multiplication obtained with 20 g · liter−1, and 14 × that obtained with the 30 g · liter−1 concentration routinely used (tree 11). Ammonium nitrate usage also improved multiplication, a 2.5 times improvement being
obtained after incorporation of 100 mg · liter−1 NH4NO3 into the medium (tree 33). Shoot cultures were responsive but relatively sensitive to addition of BA, the best improvement
in multiplication (5 times) being obtained with brief exposures to 3 mg · liter−1 BA (tree 11). Although shoot cultures were responsive to the conditions investigated, differences in shoot multiplication
and development were not displayed for several weeks. It was not possible therefore to repeat all the treatments with more
than one genotype; however, when this was possible a genotype-dependent variation in response was evident. 相似文献
32.
Cloning and restriction map of the E. coli apt gene 总被引:2,自引:0,他引:2
The apt gene coding for Escherichia coli adenine phosphoribosyl transferase has been cloned in pBR322. The restriction map of a 1.6-kb fragment containing the apt gene is presented. 相似文献
33.
David A. Morris 《Physiologia plantarum》1981,52(2):315-319
The pattern of incorporation of label into the nucleotides of axillary bud ribonucleic acid was investigated in Pisum sativum L. cv. Meteor following the application of N 6 [8-I4 C]furfuryladenine or of [8-14 C]adenine to the root system of decapitated plants and to cultured excised buds. When N 6 [8-14 C]furifaryladenine was applied to the root system label was confined to the guanine nucleotide moiety of the axillary bud ribonucleic acid; label from [8-14 C]adenine was incorporated preferentially into adenine nucleotide in the molar ratio adenine nucleotide/guanine nucleotide = 3.23. When isolated buds were incubated in media containing [8-14 C]adenine or N 6 [8-14 C]furfuryladenine, label was incorporated into both purine moieties of the ribonucleic acid. However, the relative incorporation into the guanine nucleotide fraction was considerably greater for N 6 [8-I4 C]furfuryladenine (adenine nucleotide/guanine nucleotide = 2.23) than for [8-14 C]adenine (ratio = 4.67).
It was concluded that the pattern of metabolism of adenine to guanine and its incorporation into the guanine nucleotide moiety of pea axillary bud ribonucleic acid, is influenced by the presence of a substitution in the N6 position of the adenine base. 相似文献
It was concluded that the pattern of metabolism of adenine to guanine and its incorporation into the guanine nucleotide moiety of pea axillary bud ribonucleic acid, is influenced by the presence of a substitution in the N
34.
The amounts of AMP, ADP and ATP were determined after sulfite incubation in photo-organotrophically cultivated cells of the green alga Trebouxia. D 相似文献
35.
Using steady-state relaxation spectrophotometric technique a P700 component () has been detected which was sensitized by low concentration (10?7M) DCMU in isolated broken chloroplasts of pea. The relative quantum yield of electron flux through DCMU-sensitized P700 was similar to that with methyl viologen or NADP as terminal electron acceptor and water as electron donor. Kinetic analysis showed that a small fraction (10%) of the total P700 reaction centers was sensitized by low DCMU. 相似文献
36.
37.
Edward J. Leonard Alison Skeel Peter K. Chiang Giulio L. Cantoni 《Biochemical and biophysical research communications》1978,84(1):102-109
An inhibitor of adenosylhomocysteine hydrolase, 3-deazaadenosine, caused profound inhibition of phagocytosis of opsonized erythrocytes by mouse resident peritoneal macrophages . The inhibition was evident at concentrations as low as 2×10?7M, and increased with increasing concentration and time of exposure to the analogue. It was not associated with detachment of the macrophage monolayers or with loss of cell viability. Although the inhibition was not reversible, progression of the functional impairment was interrupted by washing out the analogue. In striking contrast, phagocytic function of human blood monocytes was unaffected by 3-deazaadenosine. 相似文献
38.
The metabolism of adenine and guanine, relating to the biosynthesis of caffeine, in excised shoot tips of tea was studied with micromolar amounts of adenine-[8-14C] or guanine-[8-14C]. Among the presumed precursors of caffeine biosynthesis, adenine was the most effective, whereas guanine was the least effective. After administration of a ‘pulse’ of adenine-[8-14C], almost all of the adenine-[14C] supplied disappeared by 30 hr, and 14C-labelled caffeine and RNA purine nucleotide (AMP and GMP) synthesis increased throughout the experimental period, whereas the radioactivities of free purine nucleotides, 7-methylxanthine and theobromine increased during the first 10 hr incubation period, followed by a steady decrease. By contrast, more than 45% of the guanine-[8-14C] supplied remained unchanged even after a 120 hr period. The main products of guanine-[8-14C] metabolism in tea shoot tips were guanine nucleotides, theobromine, caffeine and the GMP of RNA. The results support the hypothesis that the purine nucleotides are synthesized from adenine and guanine via the pathway of purine salvage. Adenylate is readily converted into other purine nucleotides, whereas the conversion rate of guanylate into other purine nucleotides is very low.The results also support the view that 7-methylxanthine and theobromine are precursors of caffeine. For the origin of the purine ring in caffeine, purine nucleotides in the nucleotide pool rather than in nucleic acids are suggested. 相似文献
39.
40.