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101.
Arabinose- and succinate-enriched media induced asymbiotic nitrogenase activity inBradyrhizobium sp. 32H1. When supplemented by arabinose alone, the bacteroids became elongated, forming rosette configurations, accompanied by reduced extracellular polysaccharide production. Enrichment with succinate, in addition to arabinose, induced swelling of bacteroids. The protein profile of the outer membrane showed marked absence of several high molecular weight polypeptides in the succinate-swollen bacteroids. 相似文献
102.
D-penicillamine inhibits transactivation of human immunodeficiency virus type-1 (HIV-1) LTR by transactivator protein 总被引:4,自引:0,他引:4
D-Penicillamine, an amino acid analogue of cysteine, has been shown to inhibit the transactivation of HIV-1 LTR by the transactivator protein, tat protein. The transactivation was studied in Jurkat cells co-transfected with plasmids containing HIV-LTR sequences fused to the bacterial chloramphenicol acetyltransferase (CAT) gene and HIV tat gene. The expression of CAT activity was a measure of transactivation of LTR by the tat protein. Incubation of transfected Jurkat cells with D-penicillamine led to inhibition of CAT activity. This inhibition was found to be concentration-dependent; more than 90% inhibition of chloramphenicol acetylation was seen in extracts prepared from cultures incubated with 40 micrograms/ml of D-penicillamine. Earlier experiments have shown that D-penicillamine at 40 micrograms/ml can completely inhibit HIV-1 (HTLV-III B) replication in H9 cells [(1986) Drug Res. 36, 184-186]. These results suggest that inhibition of transactivation may be the molecular mechanism involved in the inhibition of HIV-1 replication by D-penicillamine. 相似文献
103.
104.
Tissue cultures were established from stem explants of Calotropis procera, a hydrocarbon yielding desert shrub on Murashige and Skoog's medium supplemented with 1.5 mg. 1–01 2,4-D + 0.5 mg.1–1 kinetin and polyvinylpyrrolidone. Laticifer cells were not present in young callus but were observed after 4 weeks of callus growth when examined histochemically. These young laticifers were detected in the 5th week of culture and were distinguished from surrounding cells by the presence of characteristic cytoplasm and thin walls. A group of cells with extensive branching was developed after 8 weeks of growth of the callus cultures. These cells were thick walled and contained latex particles in coagulated masses. Positive Liebermann-Burchard test proved the presence of terpenoids in these laticifers.Abbreviations 2,4-D
2,4-dichlorophenoxyacetic acid
- KIN
Kinetin
- PVP
Polyvinylpyrrolidone
- HHS
Heidenhain's Haematoxylin and safranin 相似文献
105.
Lipid classes and fatty acid distribution were analysed in the resting sporangium of Synchytrium endobioticum, the causal agent of the potato wart disease. The sporangium contents were shown to have lipid droplets, the major fatty acids there being C16.0, C18.1, and C19.0. The sporangium wall on the other hand was composed of C18.0, C18.1, C18.2, C20.0, and C20.4 fatty acids. A significantly large portion of the sporangium wall lipids contained wax esters with branched chains. 相似文献
106.
107.
108.
Pim van Hooft Herbert HT Prins Wayne M Getz Anna E Jolles Sipke E van Wieren Barend J Greyling Paul D van Helden Armanda DS Bastos 《BMC evolutionary biology》2010,10(1):106
Background
The Y-chromosomal diversity in the African buffalo (Syncerus caffer) population of Kruger National Park (KNP) is characterized by rainfall-driven haplotype frequency shifts between year cohorts. Stable Y-chromosomal polymorphism is difficult to reconcile with haplotype frequency variations without assuming frequency-dependent selection or specific interactions in the population dynamics of X- and Y-chromosomal genes, since otherwise the fittest haplotype would inevitably sweep to fixation. Stable Y-chromosomal polymorphism due one of these factors only seems possible when there are Y-chromosomal distorters of an equal sex ratio, which act by negatively affecting X-gametes, or Y-chromosomal suppressors of a female-biased sex ratio. These sex-ratio (SR) genes modify (suppress) gamete transmission in their own favour at a fitness cost, allowing for stable polymorphism. 相似文献109.
110.
An efficient and reproducible procedure for the large-scale propagation of Dendrocalamus asper is described. High-frequency direct shoot proliferation was induced in aseptic seed cultures of D. asper on modified Murashige and Skoog's (1962) medium supplemented with 1.0–10.0 mg/l benzyladenine (BA). Multiple shoots (1–25)
were formed within 5 weeks of seed culture without root formation. The shoot-forming capacity of seeds was influenced by the
BA concentration in the medium. Proliferating shoot cultures were established by repeatedly subculturing shoots in propagules
of 3 shoots each. A multiplication rate of 15–16 fold was achieved on MS medium +3.0 mg/l BA. Roots were formed on excised
propagules of 3–5 shoots when transferred to MS medium containing 10.0 mg/l indole-3-butyric acid (IBA) or 3.0 mg/l 1-naphthaleneacetic
acid (NAA). Plantlets were hardened, acclimatized and established in soil, where they exhibited normal growth.
Received: 10 April 1998 / Revision received: 18 November 1998 / Accepted: 12 December 1998 相似文献