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91.
Shoot tip, bud, leaf, stem and root explants from bearing trees, offshoots, seedlings, and asexual plantlets ofPhoenix dactylifera L. were cultured on modified Murashige and Skoog nutrient media containing 3 g/l activated charcoal, 100 mg/l 2,4-dichlorophenoxyacetic acid, 3 mg/l N 6-(Δ2-isopentyl)adenine to obtain callus. Differential morphogenetic responses were obtained from calli dependent on the explant type and parent source. Subcultured shoot tips and leafy lateral buds callus on nutrient media devoid of charcoal and supplemented with 0.1 mg/l α-naphthaleneacetic acid (NAA) produced adventitious plantlets. Subcultured leaf calli produced roots only. Root callus failed to exhibit any morphogenetic response upon subculturing. Undifferentiated non-leafy buds and stem tissues did not give rise to callus, regardless of the parent source. Generally, the best callus and embryogenetic responses from explants were obtained from seedling and plantlet parent sources. Similarly, organogenetic responses such as root formation and shoot development from shoot tips cultured on media containing 10 mg/l NAA were also related to the parent explant source. Mention of a trademark or proprietary product in the paper does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be available.  相似文献   
92.
Novikoff hepatocellular carcinoma cells possess cell-surface glycoproteins that bind the lectin, concanavalin A. A subset of Con A-binding plasma membrane glycoproteins was solubilized by addition of n-butanol to a suspension of Novikoff cells. Glycoproteins solubilized into the n-butanol-saturated aqueous phase of the two-phase mixture were purified by sequential chromatography on DEAE-cellulose and Sepharose-conjugated concanavalin A. Glycoproteins specifically bound to the Sepharose-conjugated Con A exhibited apparent Mr = 72,000 to 125,000. The plasma membrane localization of these components was inferred by their isolation from cells surface labeled with NaIO4/ NaB3H4. A xenoantiserum, raised against glycoproteins specifically bound to Sepharose-conjugated concanavalin A was employed to identify reactive components in nonionic detergent extracts of Novikoff tumor cells or rat hepatocytes surface labeled using lactoperoxidase-catalyzed iodination (125I). Major reactive peptides in extracts of Novikoff cells exhibited apparent Mr = 74,000, 82, 000, 110,000, and 135,000, while those in extracts of hepatocytes possessed apparent Mr = 98,000 and 105,000. The reactivity of the antiserum with extracts of 125I-labeled Novikoff cells was abolished by absorption of the antiserum with hepatocytes, indicating that the qualitative differences observed may result from structural modification of one or more cell-surface glycoproteins, rather than the expression of new or inappropriate glycoproteins. This antiserum will provide a useful probe to investigate alterations in the expression or structure of glycoproteins that occur as a consequence of malignant transformation or adaptation of malignant cells to growth in the ascitic form.  相似文献   
93.
94.
1,6-Diamino-2,5-anhydro-1,6-dideoxy-dl-glucitol dihydrochloride and some derivatives were synthesized from 3,5-di-O-acetyl-1,6-dibromo-1,6-dideoxy-d-mannitol. Introduction of the 2,5-anhydro ring and subsequent replacement of the terminal bromine atoms by azide gave low yields of the diazide; therefore, a reverse reaction-sequence was applied. The azido groups were reduced with hydrogen sulfide-pyridine, and the amino groups formed were methylated by using formaldehyde-formic acid and subsequently treating with borohydride. According to 13C-n.m.r. investigations, the symmetrically substituted, 2,5-anhydroglucitol derivatives are present mainly in the 4T3 [“north” (N) type of twist] conformation, whereas the analogous l-iditol derivatives mainly adopt the 3T4 [“south” (S)] type. The different quaternary salts obtained on methylation of the corresponding 1,6-bis(dimethylamino)derivatives with methyl iodide (aiming at the structure of epi-muscarine) showed no muscarine-like, biological activity.  相似文献   
95.
Surface antigens of activated and cultured human T cells were studied using peripheral blood lymphocytes activated with conditioned medium from phytohemagglutinin-activated leukocytes and maintained in liquid culture for 2 weeks with conditioned medium containing Interleukin 2. The ensuing cell population was tested for kinetic changes in cell size and for the expression of surface antigens by immunofluorescence staining with a panel of monoclonal antibodies and analysis by flow cytometry. Upon activation, the cell population progressively increased in size to large blasts, with the rapid appearance on all of the large dividing cells of the antigen recognized by OKT9, the transferrin receptor. Cells within the population continued to express the common peripheral T-cell antigens bound by OKT3 and UCHT1, and also the antigen bound by 3A1, but never the antigen bound by OKT6, a thymic cell marker. From the time of activation an increasing proportion of the T cells, up to 80%, expressed the antigen detected with OKIa and FMC4, which recognise nonpolymorphic Ia determinants. This sequence of events was followed by a general decrease in size of the cell population, a process accompanied by further phenotypic changes. The percentage of cells expressing Ia antigens decreased, but most striking was the rapid change in the OKT4:OKT8 ratio of cells within the population, from 60:40 to 40:60. Thereafter the proportions of OKT4+ to OKT8+ cells within the cultures remained relatively stable and it is suggested that these data provide evidence for a possible change in phenotype of cultured human T lymphoblasts, from OKT4 to OKT8.  相似文献   
96.
Mammalian erythropoiesis includes a step in which the nucleus is extruded through the cell membrane. We have investigated the relationship between concanavalinA (conA) plasma membrane receptors, which are known to leave the incipient reticulocyte during enucleation, and regions of the plasma membrane which bind merocyanine 540, a differentiation-specific marker of hematopoietic cells. The distribution of these two fluorescent probes was examined on living cells from the spleens of neonatal mice and on erythroleukemia cells induced to enucleate in culture. In both cases, the region of the membrane extruded with the nucleus preferentially binds conA and merocyanine 540, whereas the plasma membrane which is left behind retains the capacity to bind another lectin, wheat germ agglutinin (WGA). The implications of these findings are discussed with respect to the mechanism by which markers are eliminated from the erythrocyte cell surface.  相似文献   
97.
木姜子叶精油的化学成分研究   总被引:2,自引:0,他引:2  
采用气相色谱-质谱联用仪对产于秦岭太白山的木姜子叶的挥发油成分进行分析鉴定,从分离出的79个峰中鉴定了32种成分,其含量占挥发油总量的90.59%,主要成分为1,3,3-三甲基-乙-氧杂双环[2,2,2]辛烷(59.96%),1,8-桉油醇(8.96%),香茅醛(6.86%),2-甲基-5-(1-甲基乙烯基)环己酮(4.34%)和澄花醇乙酯(3.19%)。  相似文献   
98.
借助二次通用旋转组合设计法研究了麦草栽培姬菇配方的数学模型,以探讨利用麦草替代棉籽壳的新配方.试验结果得出了配料的取值范围及最佳栽培配方,即麦草79%,麸皮15%,玉米粉4%,过磷酸钙1%,黄豆饼粉1%.在实际生产中很有应用价值.  相似文献   
99.
100.
北京猿人遗址第四层裂变径迹法年代测定   总被引:4,自引:0,他引:4  
  相似文献   
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