Virtual target screening reveals rosmarinic acid and salvianolic acid A inhibiting metallo- and serine-β-lactamases

Rosmarinic acid (RA), a polyphenolic phytochemical, has broad-spectrum biological and pharmacological activity. A virtual target screening method termed IFPTarget combined with enzyme inhibition assays led to the identification of the clinically relevant metallo-β-lactamase (MBL) VIM-2 as one of unexploited targets of RA. The enzyme kinetic studies indicated that RA is a fully reversible, substrate-competitive VIM-2 inhibitor. The isothermal titration calorimetry (ITC) analyses revealed that the initial binding of RA to VIM-2 is mainly due to enthalpy contribution. Further inhibition assays with RA related compounds revealed that salvianolic acid A, a derivative of RA, manifests potent inhibition to VIM-2, more interestingly, which shows inhibitory activity against the NDM-1, another clinically relevant MBL subtype, and the serine-β-lactamase TEM-1 that is structurally and mechanistically distinct from the VIM-2 and NDM-1.     

Rhamnetin and Cirsiliol Induce Radiosensitization and Inhibition of Epithelial-Mesenchymal Transition (EMT) by miR-34a-mediated Suppression of Notch-1 Expression in Non-small Cell Lung Cancer Cell Lines

Radioresistance is a major cause of decreasing the efficiency of radiotherapy for non-small cell lung cancer (NSCLC). To understand the radioresistance mechanisms in NSCLC, we focused on the radiation-induced Notch-1 signaling pathway involved in critical cell fate decisions by modulating cell proliferation. In this study, we investigated the use of Notch-1-regulating flavonoid compounds as novel therapeutic drugs to regulate radiosensitivity in NSCLC cells, NCI-H1299 and NCI-H460, with different levels of radioresistance. Rhamnetin and cirsiliol were selected as candidate Notch-1-regulating radiosensitizers based on the results of assay screening for activity and pharmacological properties. Treatment with rhamnetin or cirsiliol reduced the proliferation of NSCLC cells through the suppression of radiation-induced Notch-1 expression. Indeed, rhamnetin and cirsiliol increased the expression of tumor-suppressive microRNA, miR-34a, in a p53-dependent manner, leading to inhibition of Notch-1 expression. Consequently, reduced Notch-1 expression promoted apoptosis through significant down-regulation of the nuclear factor-κB pathway, resulting in a radiosensitizing effect on NSCLC cells. Irradiation-induced epithelial-mesenchymal transition was also notably attenuated in the presence of rhamnetin and cirsiliol. Moreover, an in vivo xenograft mouse model confirmed the radiosensitizing and epithelial-mesenchymal transition inhibition effects of rhamnetin and cirsiliol we observed in vitro. In these mice, tumor volume was significantly reduced by combinational treatment with irradiation and rhamnetin or cirsiliol compared with irradiation alone. Taken together, our findings provided evidence that rhamnetin and cirsiliol can act as promising radiosensitizers that enhance the radiotherapeutic efficacy by inhibiting radiation-induced Notch-1 signaling associated with radioresistance possibly via miR-34a-mediated pathways.     

Evidence for stabilising selection acting on flowering time in Arum maculatum (Araceae): the influence of phylogeny on adaptation

The relationship between flowering time and reproductive success was investigated in the fly-pollinated, monoecious perennial herb Arum maculatum L. (Araceae). This species temporarily traps its principle pollinator, a psychodid midge. Probability of fruit set was analysed in relation to early, peak and late periods of the flowering phenology of four British populations between 1992 and 1997. In three out of five cases, plants which flowered during early and late periods were significantly less likely to set fruit. In addition, one population showed a similar relationship for percentage fruit set of individual inflorescences, and seeds from peak-flowering plants were significantly heavier. There was no variation in number of female flowers per inflorescence over the flowering season. Probability of fruit set appears to be mediated by the likelihood of trapping psychodid midges that have previously been trapped and picked up pollen, an unlikely event during early and late flowering periods when few inflorescences are open. The majority of plants in all populations produce only one inflorescence which means that timing of flowering may be crucial to reproductive success. We interpret our findings as evidence that stabilising selection may be acting on some populations and/or during some years. The ultimate cause, however, can be related to the very short (12–18 h) female phase of each inflorescence, a phylogenetically conservative trait within the Araceae. Received: 19 August 1998 / 15 February 1999     

Non-invasive assessment of parasitic nematode species diversity in wild Soay sheep using molecular markers

Considerable effort has been put into detecting and identifying parasitic nematodes in live ruminants, but to date most studies are limited to a small group of nematodes and/or to experimentally infected sheep. In this study, a PCR-based assay using species-specific primer pairs, located in the second internal transcribed spacer ribosomal DNA, was developed to identify nine different species from six different families of parasitic nematodes in a wild, unmanaged and naturally infected population of sheep. Each primer pair was tested for its specificity and sensitivity and it exclusively amplified the species it was designed for and exhibited a high degree of sensitivity. The method was applied to eggs and cultured larvae to identify the parasitic nematodes present in a pooled faecal sample from several host individuals with unknown parasite burden. To test detection reliability, a faecal sample from an individual with known parasite burden (through post-mortem analysis) was also examined. All species present could be correctly identified by PCR, but detecting very low levels and/or early stages of infection proved to be difficult. The method was also tested for its applicability to high through-put screening of faecal samples.     

枣园生态系统中害虫与天敌群落演替规律的研究

通过对太谷地区枣园害虫天敌群落的系统调查,并应用最优分割法.主分量分析法和1维和2维排序法,探讨了引起枣园害虫和天敌群落演替的主要类群及其演变规律.结果表明,群落具有明显的主导因子和时序演替格局,枣园害虫和天敌群落在前3个主分量上的变动较大,且跟随效应明显;枣园害虫和天敌群落的演替在时间过程中明显分为4个阶段:枣树发芽前、枣树展叶开花期、枣树结果期、枣果着色成熟期;利用主分量分析法,明确了主要害虫及其天敌的种类.     

大雾岭保护区穿山甲冬季生境选择

1999年12月至2001年2月,对大雾岭自然保护区穿山甲冬季栖息地的选择进行了研究,结果表明对林型选择的先后次序为针阔混交林、灌木丛、常绿阔叶林、针叶林;最偏爱针阔混交林,最不喜爱针叶林.多选择陡坡(30～ 60°);干扰源距离较远(>1 000 m),干扰程度小;林下草灌层盖度高(81% ～ 100%),隐蔽程度好; 阳坡或半阴半阳坡;中低海拔(760 ～ 1 500 m);中下坡位;水源距离较近(<500 m);乔木郁闭度适中(31% ～ 70%)的生境.较少选择上坡位,林下草灌层中低(0 ～ 50%),乔木郁闭度偏高(71%～ 100%)或偏低(0～ 30%),阴坡的生境.对洞口设置的要求是多朝南,而且要求隐蔽条件好,多数为全隐蔽或半隐蔽;最不喜爱将洞口设置在裸露、隐蔽程度差的生境,强力避免洞口向北.坡度、干扰源距离和林下草灌层盖度是影响穿山甲冬季栖息地选择的关键环境因子.     

Weather- and population density-induced infantilism in the landsnailTheba pisana in a semi-arid climate

Natural populations of the landsnailTheba pisana (Pulmonata: Helicidae) were studied in the Mediterranean coastal plains of Israel. The life cycle is annual. Egg-laying occurs in the winter and the descendants grow fast during the spring, except for a part of the population the ceases growing. These individuals, termed infantiles, retain immature size and shape and a rudimentary status of the genital system. The percentage of infantilism in the population is positively related to the density of the snail population in the winter, and is negatively related to the humidity of weather in the spring. A natural control mechanism ofT. pisana populations is proposed: (a) in a dense population of young snails infantilism prevents most of them from becoming parents and an over-sized population the following year; (b) in a humid spring a fall in the rate of infantilism enlarges the population size, thus compensating for reduced egg-laying in winter.     

锥栗自然居群遗传多样性的ISSR分析

采用20条ISSR分子标记对栗属中国特有种-锥栗(Castanea henryi)的16个自然居群进行了遗传多样性与遗传关系分析。在449份试材上共扩增得到379个位点,其中多态性位点378个,多态性位点百分率(PPL)达99.74%,平均期望杂合度(He)为0.2950,Shannon信息指数(I)为0.4522;居群水平遗传多样性为46.09%,且不同居群遗传多样性水平有较大差异,16个自然居群中以湘西居群的遗传多样性水平最高(PPL=53.30%,He=0.1861,I=0.2781),其次为靖州、庆元、昭通及都江堰居群,南平居群最低(PPL=36.94%,He=0.1202,I=0.1817)。Nei’s遗传多样性和AMOVA分析表明,居群间产生了较大的遗传分化(Gst=0.4466),锥栗自然居群内的遗传变异稍占优势(52.51%)。UPGMA聚类分析将16个锥栗居群分为2大类5亚类。湘西地区可能是锥栗的次生分布中心和现代遗传多样性分布中心,是锥栗研究的资源中心,也是最有价值的基因库,需要重点保护。     

Effects of different stressor agents on gilthead seabream natural cytotoxic activity

Several common situations in gilthead seabream (Sparus aurata L.) farming, such as air exposure, crowding and the use of anaesthetics, have been demonstrated to be stressful. In the present study, these conditions were simulated in the laboratory, after which head-kidney natural cytotoxic cell (NCC) activity was evaluated. For this, several specimens were air exposed for 2 min, returned to the aquarium and sampled from 0 to 4 days after exposure. NCC activity was significantly lower on the day following air-exposure compared with the control (rested fish) but not at any other time studied. Other fish were crowded (100 kg biomass m(-3), 2 h), returned to an aquarium with the same density as the control group (9 kg m(-3)) and sampled from 0 to 4 days after treatment. Head-kidney NCC activity was statistically increased compared with the control (resting) fish, 1 day after crowding. Anaesthesis for 1 h with 60 or 200 microl 2-phenoxyethanol l(-1)had no significant effect on NCC activity, while the use of 50 mg MS222 l(-1)for 1 h reduced such activity (by about 40%) compared with the control. In other experiments, fish were consecutively treated with crowding and anaesthetics. When treated with the lowest 2-phenoxyethanol concentration after crowding, the NCC activity inhibition was abolished compared with the activity in fish treated either with crowding or anaesthetic alone, while the use of the highest concentration increased such inhibition. The use of MS222 after crowding did not produce any differential effect compared with the fish treated with only one of the factors. In conclusion, NCC activity is affected differently according to the stress factor applied (hypoxia, crowding and/or anaesthetics). Differences in the effects provoked by these stressors on other seabream innate immune parameters are discussed.     

茶树品种‘金牡丹’自然杂交后代遗传鉴定

为了对‘金牡丹’茶树自然杂交后代进行遗传鉴定,利用EST-SSR毛细管电泳荧光标记技术对65个金牡丹自然杂交后代进行研究。结果表明,28对SSR标记共扩增出192个等位片段,平均等位基因数(Na)、平均观测杂合度(Ho)及遗传多态信息量(PIC)分别为6.86、0.540、0.532。单亲基因型已知时的累积排除概率为0.999,说明选择的28对SSR标记位点具有高度的多态性和较高的排除概率,适用于遗传分析和个体的亲子鉴定。15个‘金牡丹’自然杂交后代的遗传鉴定结果表明,MD44、JMD45、JMD47、JMD32为早生绿茶类型;JMD51、JMD53为闽北肉桂乌龙茶类型;MD2、JMD56为闽南‘铁观音’乌龙茶类型;JMD24、JMD26、JMD29、JMD55、JMD59、JMD27、JMD61为‘黄棪’乌龙茶类型。