牡丹切花衰老过程中内源激素水平变化的研究

用气相色谱(GC)和高压液相色谱(HPLC)法测定了常温(18± 2℃)和低温冷藏(4± 2℃)条件下牡丹切花衰老过程中内源激素(乙烯、IAA、ABA、CTK)含量的变化,它们对牡丹切花衰老过程的影响以及相互之间的关系进行了初步的分析和讨论。     

萝卜直根采后衰老与膜脂过氧化作用关系初探

萝卜（Ｒａｐｈａｎｕｓ ｓａｔｉｖｕｓＬ．）直根采后在室内温、湿度条件下，失重率和细胞膜相对透性直线上升，而丙二醛含量、超氧化物歧化酶活性和过氧化氢酶活性的变化则不显著。因此认为，萝卜直根木质部存在着一定程度的膜脂过氧化作用，但不是引起萝卜采后细胞膜透性增大或衰老加快的主要因素。     

Cloning and expressional characterization of soybean GmLls1 gene

In higher plants, green leaf is a very important part involved in the photosynthesis process. Good develop-ment of the leaves is the guarantee of high yields and quality. Leaf senescence that occurs in the last stage of leaf development is a genetically p…     

Role of Notch expression in premature senescence of murine bone marrow stromal cells

The aim of the present study was to investigate the role of the Notch signaling pathway in premature senescence of murine bone marrow stromal cells in vitro. The intracellular domain of Notch 1 (ICN) was transfected into cultured murine bone marrow stromal cells by lipofectamine transfection. After three days, the proliferation of transfected cells was measured by MTT assay. Cell cycle distribution was analyzed by flow cytometry. Senescence-associated beta-galactosidase (SA-beta-gal) was measured, and the percentage of positive cells was evaluated by assessing 1000 cells in random fields of view. The expressions of p53 and p21Cip1/Waf1 were analyzed by both RT-PCR and Western blot analysis. The results showed that activation of Notch signaling inhibited proliferation of murine bone marrow stromal cells with induction of G1 arrest, increased the percentage of SA-beta-gal positive cells, and upregulated p53 and p21Cip1/Waf1 mRNA and protein expression levels. Thus, the activated Notch signaling could induce premature senescence of bone marrow stromal cells through the p53-p21Cip1/Waf1 pathway.     

A comparative analysis of the cell biology of senescence and aging

Various intracellular organelles, such as lysosomes, mitochondria, nuclei, and cytoskeletons, change during replicative senescence, but the utility of these changes as general markers of senescence and their significance with respect to functional alterations have not been comprehensively reviewed. Furthermore, the relevance of these alterations to cellular and functional changes in aging animals is poorly understood. In this paper, we review the studies that report these senescence-associated changes in various aging cells and their underlying mechanisms. Changes associated with lysosomes and mitochondria are found not only in cells undergoing replicative or induced senescence but also in postmitotic cells isolated from aged organisms. In contrast, other changes occur mainly in cells undergoing in vitro senescence. Comparison of age-related changes and their underlying mechanisms in in vitro senescent cells and aged postmitotic cells would reveal the relevance of replicative senescence to the physiological processes occurring in postmitotic cells as individuals age.     

端粒、端粒酶和肿瘤、细胞衰老

端粒和端粒酶是现代生物学研究的热点,端粒的缺失与细胞的衰老,端粒酶的活性与细胞的老化及癌化均有密切的关系.文章综述了端粒和端粒酶的结构和功能及其与细胞衰老及肿瘤的关系,并在此基础之上展望了端粒酶在抗衰老、抑制肿瘤等方面的应用.     

自我调控延缓叶片衰老基因的亚克隆

利用亚克隆技术和反筛选策略,将含有延缓叶片衰老基因的双元载体上的卡那霉素抗性植物筛选标记更换为适合于水稻遗传转化的潮霉素抗性标记,并对新构建物进行了酶切鉴定和接头序列分析。     

Proline accumulation as a reliable indicator of monocarpic senescence in rice cultivars

Summary Proline content proportionally increased with leaf age as well as during aging in darkness of excised leaf segments collected from the flag, second and third leaves of the Jaya cultivar of rice. BA significantly suppressed, whereas ABA augmented, the rise of proline level in the leaf segments. Proline also increased in the attached flag, second and third leaves of all the 4 rice cultivars with the progress of reproductive development but the pattern of its accumulation was non-sequential in Jaya and Ratna and sequential in Masuri and Kalojira. Although proline accumulation was retarded and enhanced by treatment with BA and ABA, respectively, as foliar sprays, the mode of proline accumulation (non-sequential or sequential) remained unaltered.The financial assistance of the C.S.I.R., New Delhi, in the form of a research grant to MAC for carrying out the present investigation is acknowledged.     

Gigantenone,a novel sesquiterpene phytohormone mimic

Summary Gigantenone, a new eremophilane diepoxide, was isolated from the fungal plant pathogenDrechslera gigantea. It displays unique biological activity on higher plants. On most graminaceous species, the application of 18 nanomoles to a leaf surface results in the formation of green islands — localized areas of chlorophyll retention. Gigantenone is structurally unrelated to the cytokinins, yet induces the green island effect associated with these phytohormones at comparable concentrations. However, on dicotyledonous species it generally causes necrotic lesions. On host plants ofD. gigantea, gigantenone induced lesions closely resembling those appearing in natural infections. Gigantenone also induces root formation in mung bean hypocotyls and shows a high level of activity in several plant tissue culture systems.We thank the US-National Science Foundation (Grant DMB-8607347) for partially supporting this work.