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排序方式: 共有163条查询结果,搜索用时 15 毫秒
1.
2.
W. M. Van der Krieken A. F. Croes G. W. M. Barendse G. J. Wullems 《Physiologia plantarum》1988,74(1):113-118
Benzyladenine (BA) was found to regulate the number of flower buds regenerated in vitro from pedicel tissue of tobacco. Flower bud induction was particularly sensitive to BA levels in the range of 0.45 to 1.0 μ M , where a two-fold increase in concentration caused a threefold rise in the number of buds. When tissues were fed radioactive BA for 24h, only 9–12% of the counts were recovered in the original compound. The rest was present in metabolites, tentatively identified as the mono-, di- and triribotides, 7- and 9-glucosides and 9-riboside of BA. The amount of growth regulator taken up and the quantities of BA and its metabolites in the explants were all linearly related to the concentration of the medium. The internal BA concentration was ca 60% of the level in the medium after 24 h. When the concentration in the medium was raised, relatively more BA remained in the non-conjugated form. However, this change in the equilibrium between BA and the conjugates is too small to account for the steep rise in the curve representing concentration vs effect between 0.45 and 1.0 μ M . 相似文献
3.
Development of flower buds in thin-layer cultures of floral stalk tissue from tobacco: Role of hormones in different stages 总被引:4,自引:0,他引:4
The in vitro development of flower buds was studied on tissue explants of epidermis and subepidermal cortex from the flower stalks of Nicotiana tabacum L. cv. Samsun. The number of flower buds formed depended mainly on cytokinin concentration. Auxin acted as a modifier in a complex way. In early development, NAA at 1 μ M decreased the number of buds initiated and delayed bud emergence. At a later stage, auxin promoted bud outgrowth at the same concentration. Optimal results were obtained when explants were first incubated at low auxin concentration for 3–5 days and subsequently transferred to an elevated auxin level. Physiological processes that lead to flower bud initiation start very soon after the onset of incubation. This was inferred from experiments whereby explants were first cultured at an inductive cytokinin concentration and then transferred to a non-inductive hormone level. 相似文献
4.
Two methods to produce the 17-cyanohydrin, using potassium cyanide in acetic acid/methanol or acetone cyanohydrin with aqueous sodium hydroxide, were followed with 9 alpha-hydroxyandrost-4-ene-3,17-dione, both providing 17 beta-cyano-9 alpha,17 alpha-dihydroxyandrost-4-en-3-one. The selectivity of one of these methods, that which uses acetone cyanohydrin, is not in agreement with a comparable reaction with the 9 alpha-unsubstituted androst-4-ene-13,17-dione to give the 17 alpha-cyano-17 beta-hydroxy product, as reported in the literature and confirmed by us. The 9 alpha-hydroxy and 17 alpha-hydroxy groups were used for the regioselective introduction of 9(11)- and 16(17)-double bonds by dehydrating 17 beta-cyano-9 alpha,17 alpha-dihydroxyandrost-4-en-3-one under different conditions. 相似文献
5.
The contrasting role of auxin in submergence-induced petiole elongation in two species from frequently flooded wetlands 总被引:5,自引:0,他引:5
Jan G. H. M. Rijnders Gerard W. M. Barendse Cornelis W. P. M. Blom Laurens A. C. J. Voesenek 《Physiologia plantarum》1996,96(3):467-473
The involvement of auxin in the submergence-induced petiole elongation has been investigated in Rumex palustris and Ranunculus sceleratus. Both wetland species are capable of enhanced petiole elongation upon submergence or treatment with exogenous ethylene (5μl l−1 ). Treatment of intact Rumex palustris plants with 1-naphthalene acetic acid (NAA) at 10−4 M enhanced petiole elongation, while treatment with N -1-naphthylphthalamic acid (NPA) had no effect on petiole elongation. The elongation response after NAA or NPA treatment was comparable for plants in both submerged and drained conditions. Pre-ageing of detached petioles of Rumex palustris for 3 h in light or in dark conditions had no effect on the submergence-induced elongation. In comparison to intact plants, detached petioles of Rumex palustris , with or without lamina, did not show significant differences in responsiveness to IAA between drained or submerged conditions. This was in contrast to Ranunculus sceleratus where submergence caused a clear increase in responsiveness towards IAA. Removal of the lamina, the putative source of auxin, or treatment with NPA did not hinder the submergence-induced elongation of detached Rumex palustris petioles, but severely inhibited elongation of detached Ranunculus sceleratus petioles. This inhibition could be restored by application of NAA, suggesting the specific involvement of auxin in the submergence response of Ranunculus sceleratus. It is concluded that, in contrast to Ranunculus sceleratus , auxin is probably not involved in the submergence-induced petiole elongation of Rumex palustris. 相似文献
6.
L. Ferretti B. G. D. Urquhart A. Eggen I. Olsaker B. Harlizius B. Castiglioni A. Mezzelani S. Solinas Toldo U. Thieven Y. Zhang A. L. G. Morgan V. M. Teres M. Schwerin I. Martin-Burriel B. P. Chowdhary G. Erhardt I. J. Nijman E. P. Cribiu W. Barendse H. Leveziel R. Fries J. L. Williams 《Mammalian genome》1997,8(1):29-36
The mapping strategy for the bovine genome described in this paper uses large insert clones as a tool for physical mapping
and as a source of highly polymorphic microsatellites for genetic typing, and was one objective of the BovMap Project funded
by the European Union (UE). Eight-three cosmid and phage clones were characterized and used to physically anchor the linkage
groups defining all the bovine autosomes and the X Chromosome (Chr). By combining physical and genetic mapping, clones described
in this paper have led to the identification of the linkage groups corresponding to Chr 9, 12, 16, and 25. In addition, anchored
loci from this study were used to orient the linkage groups corresponding to Chr 3, 7, 8, 9, 13, 16, 18, 19, and 28 as identified
in previously published maps. Comparison of the estimated size of the physical and linkage maps suggests that the genetic
length of the bovine genome may be around 4000 cM.
Received: 1 July 1996 / Accepted: 13 September 1996 相似文献
7.
8.
9.
S. E. Johnson S. S. Moore R. MacKinnon D. J. S. Hetzel W. Barendse 《Mammalian genome》1995,6(8):529-531
The cosmid-derived microsatellite CSSM 25 has previously been shown to map to bovine syntenic group U2 by link-age and hybrid somatic cell analysis. We have mapped the cosmid by fluorescent in situ hybridization to bovine Chromosome (Chr) 9q17-21 and ovine Chr 8q17-21 and hence assign U2 to Chr 9 in cattle. Bovine Chr 9 and ovine Chr 8 show strong banding pattern homology, and the localization of CSSM 25 to the same region confirms the strong conservation of gene locations on these chromosomes. 相似文献
10.
Agar diffusion of imbibed seeds yielded significant amounts of diffusible Gibberellin-like substances. An analysis of the extractable and diffusible gibberellin-like substance, including an analysis of the remaining imbibition water of the seeds, indicated that a significant part of these gibberellin-like substances could be attributed to a net biosynthesis of these substances in the imbibing seeds. At the same time it was found that water diffusion yielded considerably more gibberellin-like activities than comparable agar diffusions i.e. 10 to 12 fold in general.Agar as well as water diffusion showed a temperature effect with regard to the yield of gibberellin-like substances particularly during the first 6 h of diffusion. The yield of these substances is lower at 10°C, and remains lower as shown with consecutive diffusions, in comparison with the yields at 20°C or 30°C.With both agar and water diffusion the sum of activities obtained with consecutive diffusions is always higher, often considerably higher, than equal periods of continuous diffusion which is probably due to inactivation and/or interference of inhibitory substances with the bioassay responses. Finally, water diffusates of both seeds and seedlings of the normal growing cv. Violet of Japanese morning glory contained considerably more gibberellin-like activities than those of the dwarf cv. Kidachi which indicated that normals synthesize more gibberellins than dwarfs. 相似文献