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71.
赤霉素与脱落酸对番茄种子萌发中细胞周期的调控 总被引:11,自引:0,他引:11
利用细胞流检仪检测番茄(Lycopersicon esculentum Mill.) GA-缺陷型、ABA-缺陷型和相应的正常品种(野生型)成熟种子胚根尖细胞倍性水平时发现:GA-缺陷型和野生型种子绝大多数细胞DNA 水平为2C,而ABA-缺陷型种子则含有较多的4C细胞。在标准发芽条件下,ABA-缺陷型和野生型种子浸种1 d 后胚根尖细胞DNA 开始复制,随后胚根突破种皮而发芽。然而GA-缺陷型种子除非加入外源GA,否则既不发生细胞DNA 复制,也不发芽。这说明内源GA 是启动番茄种子胚根尖细胞DNA 复制的关键因素,同时也说明番茄根尖细胞DNA 复制是种子发芽的必要条件。实验证明:ABA 不抑制细胞DNA 合成,但阻止G2 细胞进入到M 期。外源ABA处理野生型种子与渗控处理结果相似,可以大幅度提高胚根尖4C/2C细胞的比例,但抑制种子的最终发芽 相似文献
72.
干燥番茄(Lycopersicon esculentum Mill. cv. Moneym aker)种子浸种吸水有明显的3 个阶段,尽管种子不同部分吸水的速度不一样,但整粒种子需10~12 h 才能基本完成第一阶段的吸水。胚乳对种胚伸长和生长的机械压力明显阻碍种胚的吸水,即使在第二阶段整个种子水势与浸种溶液基本达到水分平衡时,种胚的水势仍然低于整个种子水势0.6~0.9 MPa。发芽过程中GA 和ABA不直接影响番茄种子吸水。番茄种胚水势与含水量的关系呈幂指数的正相关。无论在浸种还是渗控处理过程中,番茄种胚压力势的总变化趋势是下降的 相似文献
73.
Summary A novel taxol determination method which involves the tubulin-assembly stimulation is described. The tubulin-assembly was monitored by turbidity change at 350nm. In a limited range of taxol concentration (0 to 24 M), taxol stimulated tubulin-assembly linearly. And this linear relation was observed from 20min to 30min after the reaction started. Bioactive derivatives of taxol, such as cephalomanin and 7-epi-10-deacetyltaxol also stimulated the tubulin-assembly. However, baccatin III, which was known as less active taxol derivative did not stimulate tubulin assembly. This result showed that the stimulation of tubulin assembly has a relationship with the antimiotic activity. This assay method have several advantages. 1) Time required for the measurement is relatively short. 2) Multiple samples can be measured simultaneously. 3) It can remove interference of less active taxane compounds more selectively than immuno-assay. Consequently, this method can be used to determine taxol concentration in biological samples. Especially, this method can be used for large scale selection of cell line and primary screening of new antimiotic compounds. 相似文献
74.
植物生活史对策的进化 总被引:19,自引:0,他引:19
植物生活史对策的进化班勇(中国林业科学院林业研究所,北京100091)EvolutionofLifeHistoryStrategyinPlants¥BanYong(ResearchInstituteofForestry,ChineseAcademyo... 相似文献
75.
We examined the effect of prostaglandin E2 (PGE2), in the presence or absence of cortisol, on bone formation in 21-day fetal rat calvaria maintained in organ culture for 24 to 96 h. [3H]Thymidine and [3H] proline incorporation were used to assess DNA and collagen synthesis, respectively. Changes in dry weight and DNA content were assessed after 96 h.PGE2 (10−7 M) stimulated both DNA and collagen synthesis in calvaria. The effect on DNA synthesis was early (24 h), transient and limited to the periosteum. Collagen synthesis was stimulated at a later time (96 h), predominantly in the central bone. Cortisol (10−7 M) inhibited DNA and collagen synthesis. The addition of PGE2 reversed the inhibitory effects of cortisol on DNA synthesis and content and increased collage synthesis in central bone to levels above control untreated cultures.We conclude that PGE2 has stimulatory effects on bone formation and can reverse the inhibitory effects of cortisol. Hence the effects of cortisol may be mediated in part by their ability to reduce the endogenous production of prostaglandins. 相似文献
76.
Myelin development in infant brain 总被引:1,自引:0,他引:1
Myelin was isolated from subcortical areas of ten human brains, with ages ranging from 24 days to 350 days-of-age; samples were subsequently analyzed for lipid composition. Eight infants were victims of Sudden Infant Death Syndrome, and two infants were accident cases. Gray and white matter samples from each brain were also dissected and analyzed. Galactolipids were only 12% of the total lipids in white matter from brains of infants that were 24 days-of-age, a time when myelination was just starting in the subcortical areas. At 175 and 350 days of age, myelination was well underway and galactolipids measured 22% of the total lipids. Total phospholipids decreased (65% to 54%) in white matter during development, with the decrease mostly in phosphatidylcholine (23% to 15%). Even though there was little white matter present at early ages, myelin could be isolated. Surprisingly, the lipid composition of myelin, from the 24-day-infant brain was similar to that from adult brain. Galactolipids were 22% of the total lipids, cholesterol, 23%, and phospholipids, 52%. These results suggest that only subtle remodeling of myelin occurs in humans once myelination commences. All four major gangliosides were present in myelin during this first year of development. Interestingly, the yield of myelin from the 350-day-old infant subcortical white matter was similar to that from an adult. Thus major tracts in this area may have acquired most of the myelin by one year-after-birth. Since the control samples blend quite well into the developmental pattern obtained, it is believed there are no abnormalities in myelin lipids from SIDS infants. 相似文献
77.
-Yong W. K. and Dobson C. 1982. The passive transfer of proctective immunity against Angiostrongylus cantonensis with immune lymph node cells from different lymphoid tissues in rats. International Journal for Parasitology12: 423–425. Lymph node cells from the posterior cervical and mesenteric lymph nodes of immune rats passively protected syngeneic recipient rats against Angiostrongylus cantonensis better than cells from the spleen, thymic and inguinal lymph nodes either as reduced worms burdens and/or stunted growth. No antibody was detected in the sera of recipient rats after transfer of the cells and before infection which suggested that the protection was cell- rather than antibody-mediated. 相似文献
78.
79.
黑胸大蠊(Periplaneta fuliginosa)病毒的分离及某些特性 总被引:2,自引:1,他引:1
从黑胸大蠊(Periplaneta fuliginosa)自然罹病的虫尸中分离得到一株非包涵体病毒。将病毒悬液均匀拌入无菌饲料并供食154~169日龄黑胸大蠊健康若虫时,能使其感染、发病,死亡率可达98%以上。在电子显微镜下观察时,病毒为球形二十面体颗粒,直径约23nm。病毒悬液具有典型核蛋白紫外吸收光谱。病毒用DNase和RNase处理并经吖啶橙染色、二苯胺和苔黑酚试验及甲醛反应证明:该病毒含有单链DNA。以上特性与细小病毒科的特征有点类似。 相似文献
80.
海三棱藨草群落是生长在海岸带滩涂原生裸地上的原生植被,在上海地区分布面积达20多万亩。本项工作研究了上海市南汇县东海农场海堤外侧滩涂上海三棱藨草种群的物候和分布格局。根据滩涂高程以及海三棱藨草种群生长状况,可以划分成三个地带,即地带A,海三棱藨草与芦苇群落交错区;地带B,海三棱藨草种群生长最适的中潮位地带;地带C,梅三棱藨草种群定居地带。由于三个地带内,生境条件不同,海三棱藨草种群的物候有明显差异。从地带A至C,海三棱藨草种群的分布格局依次为随机分布、均匀分布和随机分布或群聚分布。其空间分布格局在随时间变化的同时也在空间上改变其位置。 相似文献