湖北八角莲属植物过氧化物酶同工酶分析

用聚丙烯酰胺凝胶电泳分离湖北八角莲属４种植物的过氧化物酶同工酶,并采用薄层扫描和排序分析法,对其亲缘关系进行了比较分析。结果表明,六角莲与八角莲、小八角莲、乌云伞的亲缘关系较远。小八角莲、八角莲与乌云伞亲缘关系较近,同时还为乌云伞作为一个独立种提供了佐证。     

竹柏叶精油化学成分的研究

竹柏叶精油化学成分的研究吴惠勤,王艇,苏应娟,张桂英（中国广州分析测试中心广州５１００７０）（中山大学生命科学学院广州５１０２７５）ＡＳＴＵＤＹＯＮＣＨＥＭＩＣＡＬＣＯＮＳＴＩＴＵＥＮＴＳＯＦＥＳＳＥＮＴＩＡＬＯＩＬＦＲＯＭＰＯＤＯＣＡＲＰＵＳＮＡＧ...     

红豆杉科、三尖杉科和罗汉松科的实验分类学研究进展

红豆杉科、三尖杉科和罗汉松科的系统位置及系统发育关系长期以来都存有争议,本文对此三科在实验分类学方面的研究进展及趋势作了综述。     

罗汉松叶精油化学成分的研究

罗汉松叶精油化学成分的研究苏应娟,王艇,张宏达（中国科学院武汉植物研究所武汉４３００７４）（广州中山大学生命科学学院５１０２７５）关键词罗汉松,精油,化学分类ＡＳＴＵＤＹＯＮＣＨＥＭＩＣＡＬＣＯＮＳＴＩＴＵＥＮＴＳＯＦＥＳＳＥＮＴＩＡＬＯＩＬＦＲＯＭ...     

Isolation and characterization of insecticidal activity of (Z)-asarone from Acorus calamus L.

The insecticidal activity of Acorus calamus L. rhizome‐derived material against adults of Sitophilus zeamais Motschulsky was examined by using repellency method and contact toxicity. The biologically active constituent of the A. calamus rhizome was separated and identified. The results showed that the ethanol extract of A. calamus had strong repellency and contact effect to S. zeamais and the active constituent of the A. calamus was characterized as (Z)‐asarone by spectroscopic analysis. Responses from the tests varied with exposure times and doses. In the repellency test, ethanol extract of A. calamus had 93.92% repellency at 629.08 μg/cm² but only 71.38% at 157.27 μg/cm² 12 h after treatment. As a contrast, (Z)‐asarone showed 84.50% repellency at 314.54 μg/cm² and 77.02% at 78.63 μg/cm² 12 h after treatment. In the filter paper diffusion test, ethanol extract of A. calamus caused 95.56% and 17.78% mortality to S. zeamais at 314.54 μg/cm² and 78.63 μg/ cm² 4 days after treatment, while (Z)‐asarone brought about 100.00% and 15.56% mortality at 40.89 μg/cm² and 15.73 μg/cm² respectively. These results indicate that the insecticidal activity of the A. calamus extract may be due to (Z)‐asarone.     

Phylogeny and evolutionary divergence times in Apterosperma and Euryodendron: Evidence of a Tertiary origin in south China

Apterosperma and Euryodendron, monotypic genera in Theaceae (sensu lato), are endemic and restrictedly distributed in south China. The two genera are not included in the major classification systems. However, their systematic position and origin have been subject to intense debate in the last decade. In this study, the phylogeny and divergence times of both Apterosperma and Euryodendron were inferred using combined dataset of chloroplast DNA trnL-F and atpB-rbcL non-coding sequences and nrDNA ITS sequences. The results from Bayesian inference, maximum parsimony, and maximum likelihood consistently showed that (i) Euryodendron is a valid genus, which is closer to Eurya than to Cleyera and (ii) Apterosperma is a genus of the tribe Theeae along with Tutcheria and Camellia. It was first reported that the divergence time of Apterosperma was 61.98 million years ago (mya), whereas that of Euryodendron 20.51 mya, indicating Tertiary origins in south China. The divergence of Apterosperma appears to be the result of increased ecological opportunity after Cretaceous/Tertiary extinction events and related with high temperatures and high humidity environments. By contrast, the origin of Euryodendron may be associated with historical mountain building events as well as the significant climate changes that established cooler temperatures prevailing until today.     

沙埋与水分对科尔沁沙地主要固沙植物出苗的影响

蒿属半灌木乌丹蒿(Artemisia wudanica)、白沙蒿(A. sphaerocephala)、差不嘎蒿(A. halodendron)是科尔沁沙地的主要固沙植物。其中乌丹蒿和差不嘎蒿是科尔沁沙地的本土植物,白沙蒿为来自于库布齐沙漠、毛乌素沙地的飞播植物。设置了 5个沙埋深度(0.5、1.0、1.5、2.0和3.0 cm)和 4个水分梯度(86、171、257和 342 mL,分别模拟每月25、50、75和100 mm的降雨量),以探讨3种植物幼苗出土对沙埋和水分的响应。结果表明,沙埋与水分均显著影响着3种蒿属植物的幼苗出土(P < 0.001)。3种植物最适沙埋深度在0.5-1.5 cm范围内,萌发出土时适宜水量要高于当地种子萌发期的平均降水量(50 mm/月)。两种固沙先锋植物乌丹蒿和白沙蒿的种子出苗率均显著高于差不嘎蒿,乌丹蒿较白沙蒿也明显为高,尤其在水分缺乏时,表现出两种先锋植物种子出苗对干旱有更好的适应性。协方差分析表明,乌丹蒿幼苗死亡率显著高于白沙蒿和差不嘎蒿(P < 0.05),在达到75 mm/月降水量时,3种植物的出苗较好,但不能满足乌丹蒿幼苗生长对水分的需求,而实际种子萌发期的降水量平均只有50 mm/月。因而降水的缺乏导致乌丹蒿种群更新出现问题,加之飞播植物的竞争,使得近几年科尔沁沙地较多乌丹蒿种群出现衰退。     

Design,synthesis and pharmacological evaluation of novel tacrine–caffeic acid hybrids as multi-targeted compounds against Alzheimer’s disease

A novel series of tacrine–caffeic acid hybrids (5a–f) were designed and synthesized by combining caffeic acid (CA) with tacrine. The antioxidant study revealed that all the hybrids have much more antioxidant capacities compared to CA. Among these compounds, 5e showed the highest selectivity in inhibiting acetylcholinesterase (AChE) over butyrylcholinesterase (BuChE). Enzyme kinetic study had suggested that 5e binds to both catalytic (CAS) and peripheral anionic sites (PAS) of AChE. Moreover, compound 5e also inhibited self- or AChE-induced β-amyloid_1–40 aggregation, as well as had potent neuroprotective effects against H₂O₂- and glutamate- induced cell death with low toxicity in HT22 cells.     

DNA polymerase eta is targeted by Mdm2 for polyubiquitination and proteasomal degradation in response to ultraviolet irradiation

DNA polymerase eta (PolH), the product of the xeroderma pigmentosum variant (XPV) gene and a Y-family DNA polymerase, plays a pivotal role in translesion DNA synthesis. Loss of PolH leads to early onset of malignant skin cancer in XPV patients and increases UV-induced carcinogenesis. Thus, the pathways by which PolH expression and activity are controlled may be explored as a strategy to prevent UV-induced cancer. In this study, we found that Mdm2, a RING finger E3 ligase, promotes PolH degradation. Specifically, we showed that knockdown of Mdm2 increases PolH expression in both p53-proficient and -deficient cells. In addition, we showed that UV-induced PolH degradation is attenuated by Mdm2 knockdown. In contrast, ectopically expression of Mdm2 decreases PolH expression, which can be abrogated by the proteasome inhibitor MG132. Moreover, we showed that Mdm2 physically associates with PolH and promotes PolH polyubiquitination in vivo and in vitro. Finally, we showed that knockdown of Mdm2 increases the formation of PolH replication foci and decreases the sensitivity of cells to UV-induced lesions in a PolH-dependent manner. Taken together, we uncovered that Mdm2 serves as an E3 ligase for PolH polyubiquitination and proteasomal degradation in cells under the basal condition and in response to UV irradiation.