Seasonal Rhythms of Structure and Behaviour of Vascular Cambium in Ficus rumphii

Cambial structure and activity of Ficus rumphii Blume vary withthe changes in local climate. The cambial cells start swellingearly in April prior to the onset of periclinal divisions whichare most frequent in August. Cell division stops in October.During the growth season, initiation as well as cessation ofthe phloem production precedes that of xylem. A moderately hightemperature is correlated with the cambial reactivation. Onceinitiated, the activity continues at relatively low temperatures.Hot and dry environment favours the phloem production, whereashot and moderately humid conditions induce xylogenesis. Thesize and relative proportion of cambial initials also changewith season. Fusiform initials are shorter and broader duringthe rainy season (July–September) than for the rest ofthe year. Multiseriate and triseriate rays, as also the tallrays, outnumber the other types of rays throughout the year. Ficus rumphii, vascular cambium, phenology, climatic variation     

Novel urease inhibitors from Daphne oleoids

Phytochemical investigations on the chloroform and ethyl acetate soluble fractions of the roots of the Daphne oleoids led to the isolation of the coumarin glycosides 1–6. Compound 5 with IC₅₀ values 22.05 and 26.30 μM repectively, was found to be the most active of these compounds when screened against Bacillus pasteurii and jack bean urease enzymes in a concentration-dependent fashion.     

CHANGES IN PROTEIN BIOSYNTHESIS DURING GIBBERELLIC ACID INDUCED INDUCTION AND FORMATION OF ANTHERIDIUM IN THE FERN ANEMIA PHYLLITIDIS

Changes in protein biosynthesis have been studied during the induction and formation of antheridium in Anemia phyllitidis .
Based on incorporation of ¹⁴C-amino acid mixture into TCA precipitable material two distinct phases of accelerated protein biosynthesis were observed. First phase initiates at 4th day, while the second at 8th day of development. The first phase is likely associated with antheridium induction and second with spermatogenesis. From electrophoretic pattern of proteins on stained acrylamid gels and from radioactivity profiles of labelled proteins distinct quantitative differences between vegetative and reproductive prothalli were observed at different stages of antheridial development. Radioactivity profiles reveal characteristic pattern of each stage of antheridial differentiation.     

阿尔次海默病tau蛋白异常修饰与其功能的关系

阿尔次海默病易溶型胞浆tau和难溶型双螺旋丝中的tau均被异常磷酸化和异常糖基化修饰.异常修饰的tau丧失其促微管组装活性,用不同蛋白磷酸酯酶对难溶型双螺旋丝中的tau去磷酸化处理后可不同程度恢复其促微管组装生物学活性.单纯去糖基化处理只在很小限度恢复tau的功能,但去糖基化预处理可增强去磷酸化对tau上述活性的恢复.提示:a.tau的异常磷酸化是导致其功能活性丧失的直接因素,而糖基化修饰可能通过对其结构的影响而间接对tau功能活性发挥作用;b.蛋白磷酸酯酶可部分抑制和逆转阿尔次海默病的脑病理损伤.     

蛋白激酶对τ蛋白阿尔茨海默样磷酸化的调节作用

微管相关蛋白τ的异常磷酸化是阿尔茨海默病（AD）神经原纤维退变的重要机制之一.研究发现：酪蛋白激酶-1（CK-1）, cAMP依赖性蛋白激酶（PKA）和糖原合成酶激酶-3（GSK-3）均可不同程度催化重组τ蛋白发生磷酸化,从而不同程度抑制τ蛋白促微管组装的生物学功能.如果先将τ蛋白与PKA预温2 h后再和GSK-3温育,则发现τ蛋白磷酸化程度比单纯用GSK-3处理显著增高,生物学活性则显著降低,电镜检测几乎看不见微管形成.结果提示：PKA和GSK-3在τ蛋白的AD样磷酸化及其功能抑制中具有正性协同作用.     

阿尔次海默病tan蛋白异常修饰与其功能的关系

阿尔次海默病易溶型胞浆ｔａｕ和难溶型双螺旋丝中的ｔａｕ均被异常磷酸化和异常糖基化修饰。异常修饰的ｔａｕ丧失其促微管组装生,用不同蛋白磷酸酯酶对难溶型双螺旋丝中的ｔａｕ磷酸化处理后可不同程度恢复其促微管组装生物学活性。     

糖原合成酶激酶-3对τ蛋白磷酸化作用的研究

糖原合成酶激酶 ３（ Ｇ Ｓ Ｋ ３）在 ３０℃与 τ蛋白保温 ４ ｈ 可催化 １７±０４ ｍ ｏｌ磷酸参入 １ ｍ ｏｌτ蛋白 将磷酸化的 τ蛋白经胰蛋白酶消化, Ｆｅ Ｃｌ３ 亲和柱分离及 Ｃ１８反相高压液相层析纯化后,再用高压电泳,手工 Ｅｄｍ ａｎ 降解及自动氨基酸序列分析等检测技术,对其磷酸化位点进行鉴定 结果发现： Ｇ Ｓ Ｋ ３ 可使 τ蛋白 Ｔｈｒ １８１, Ｓｅｒ １８４, Ｓｅｒ ２６２, Ｓｅｒ ３５６ 和 Ｓｅｒ ４００ 发生磷酸化 其中 Ｓｅｒ ２６２ 和 Ｓｅｒ ４００ 为 Ａｌｚｈｅｉｍ ｅｒ 病（ Ａ Ｄ）τ蛋白的异常磷酸化位点根据上述磷酸化作用仅轻度抑制τ蛋白生物学活性,推测： Ａ Ｄ τ蛋白 Ｓｅｒ ２６２ 和 Ｓｅｒ ４００ 的磷酸化可能不是决定其生物功能的关键性位点,单纯 Ｇ Ｓ Ｋ ３ 不能复制 Ａ Ｄ 样 τ蛋白的病理改变 