Terpenes and phenolics in response to nitrogen fertilization: A test of the carbon/nutrient balance hypothesis

Nitrogen fertilization resulted in a linear increase in the growth ofAbies grandis seedlings, but linear decrease in foliage concentrations of phenolic compounds. These data are consistent with the inverse relationship between growth and production of carbonbased secondary chemicals predicted by the carbon/nutrient balance (CNB) hypothesis. However, in contrast to predictions of the CNB hypothesis, nitrogen fertilization had no effect on foliage terpene concentrations. The results suggest that not all carbon-based chemicals respond in the same manner to environmental variation, and that the carbon/nutrient balance hypothesis does not adequately explain all patterns of environmentally-induced variation in secondary metabolism.     

生物膜中群体感应因子细菌的分离及成膜能力

从硝基苯甲酸废水处理系统的生物膜中分离到2株分泌酰基高丝氨酸内酯(AHL)群体感应信号分子的菌株M10和M22,测试表明M10产生4种AHL信号分子,M22产生3种AHL信号分子.以E.coliDH5α为对照,测定了这2株菌的成膜能力及群游力,M10和M22均表现出一定的成膜力和群游力,对比而言,M22的成膜能力较强,而M10的群游能力较强,M10和M22经个体形态、生理生化反应及16SrDNA测序初步鉴定均属Aeromonassp..     

热脱附气相色谱质谱法测定空气中萜烯有机物

采用自动热脱附(ATD)和气相色谱质谱(GC/MS)联用技术,研究并建立了空气中11种萜烯有机物的测试方法。采用吸附剂Tenax TA进行吸附捕集时,α-蒎烯、莰烯、β-蒎烯极易发生穿透现象,三者的穿透率超过60%;与Tenax TA相比,吸附剂Carbopack B/CarbosieveTMS-Ⅲ可有效抑制萜烯有机物的穿透行为。ATD优化的操作参数为:一级脱附温度和时间分别选择为260℃和10 min,冷肼温度为-20℃,二级热脱附温度和时间分别为280℃和5 min。该方法测试结果准确,重现性和稳定性较好,方法的加标回收率为89%¹12%,相对标准偏差(RSD)小于11%。将该法用于室内空气中萜烯类有机物的测试,发现不同空气样品中均含有多种萜烯有机物,其总量约占总挥发性有机物(TVOC)的15%112%,相对标准偏差(RSD)小于11%。将该法用于室内空气中萜烯类有机物的测试,发现不同空气样品中均含有多种萜烯有机物,其总量约占总挥发性有机物(TVOC)的15%⁶5%,出现几率较大的有α-蒎烯、β-蒎烯、香叶烯、蒈烯、柠檬烯和柏木烯,松油醇较少出现。     

厌氧氨氧化污泥群体感应信号分子检测及影响研究

厌氧氨氧化作为一种新型的脱氮工艺具有很好的应用前景,但厌氧氨氧化污泥富集培养困难.本研究以处理垃圾渗滤液的污泥作为接种污泥,在升流式厌氧污泥反应器(UASB)中启动厌氧氨氧化过程;检测驯化成功的厌氧氨氧化污泥中是否存在群体感应信号分子;并通过添加外源信号分子(cis-11-Methyl-2-dodecenoic acid,DSF和N-acyl-homoserine lactone,AHL),探究信号分子对厌氧氨氧化污泥附着生长能力的影响.结果表明,UASB反应器在运行150 d后,总氮去除率达到80%,菌群结构中厌氧氨氧化菌所占比例超过了20%,成功启动厌氧氨氧化工艺,且厌氧氨氧化污泥中存在低浓度的AHLs信号分子;人为添加3-碳位置取代基为羰基的AHLs(3-oxo-C6-HSL、3-oxo-C8-HSL、3-oxo-C10-HSL和3-oxo-C12-HSL)信号分子均能促进厌氧氨氧化污泥附着生长,而3-碳位置无取代基的AHLs中只有C12-HSL和C6-HSL存在积极影响,C8-HSL、C10-HSL和DSF信号分子对厌氧氨氧化污泥的附着生长能力并没有促进作用.     

高温和干旱对银杏光合作用、叶片中黄酮苷和萜类内酯含量的影响

为了探讨高温和干旱的相互作用对银杏(Ginkgobiloba)生长及叶内次生代谢物的影响,设干旱、高温(夜间30℃)和干旱+高温3个处理,测定了2年生银杏幼苗的生长指标、光合特性、叶片水势、气孔导度以及叶内黄酮苷和萜类内酯的含量。与对照(未经干旱或高温处理)相比,高温引起银杏叶片最大净光合速率降低,气孔导度和光补偿点增加;干旱处理后,银杏最大净光合速率、气孔导度和叶片水势均降低,但光补偿点以及叶片黄酮苷和萜类内酯含量增加,表观量子产量变化不明显。高温和干旱共同作用下,银杏光补偿点和呼吸速率增高,光饱和点显著降低,根冠干重比无统计学上显著变化,但总干重降低。上述结果说明干旱和高温降低了银杏对光的适应范围,银杏光能利用效率变低,气孔导度下降,最大净光合速率降低,呼吸作用增强,抑制了生长;干旱引起黄酮苷和萜类内酯含量增加的幅度大于高温。     

三花紫菊的化学成分

从三花紫菊(NotoseristrifloraShih)(3)全草的甲醇提取物中分离鉴定出17个化合物,其中14个为倍半萜内酯dihydrosantamarine(1),sonchusideA(2),annuolidesD(3),ixerisosideD(4),11β,13-dihydro-hyporadiolide-8-0-(2-methylacrylate)(5),hyporadio1ide-8-0-(2-methylacrylate)(6),hypochoerolideG(7),hypochoerolideE(8),11β,13-di-hydrolactucin(9),cichoriosideB(10),jacquilenin(11),austricin(12),crepidiasideA(13)和crepidiasideB(14),另外3个化合物分别鉴定为3,5-二甲氧基-4-羟基苯甲醛(15),β-谷甾醇(16)和胡萝卜苷(17).上述化合物均为首次从该植物中分离得到.图1表1参14     

Curvularin from Penicillium baradicum baghdadi NRRL 3754, and biological effects

Abstract

Curvularin, a fungal metabolite similar in chemical structure to zearalenone, a potent estrogen, was tested for its estrogenic effects to gilts. No estrogenicity was observed to 60 kg gilts after feeding curvularin per os at a rate of 10 mg per day for 5 days. Curvularin was also nontoxic to mice and chick embryo.     

Profile of the culturable microbiome capable of producing acyl-homoserine lactone in the tobacco phyllosphere

Bacterial populations coexisting in the phyllosphere niche have important effects on plant health. Quorum sensing (QS) allows bacteria to communicate via diffusible signal molecules, but QS-dependent behaviors in phyllosphere bacterial populations are poorly understood. We investigate the dense and diverse N-acyl-homoserine lactone (AHL)-producing phyllosphere bacteria living on tobacco leaf surfaces via a culture-dependent method and 16S rRNA gene sequencing. Our results indicated that approximately 7.9%-11.7% of the culturable leaf-associated bacteria have the ability to produce AHL based on the assays using whole-cell biosensors. Sequencing of the 16S rRNA gene assigned the AHL-producing strains to two phylogenetic groups, with Gammaproteobacteria (93%) as the predominant group, followed by Alphaproteobacteria. All of the AHL-producing Alphaproteobacteria were affiliated with the genus Rhizobium, whereas the AHL-producing bacteria belonging to the Gammaproteobacteria mainly fell within the genera Pseudomonas, Acinetobacter, Citrobacter, Enterobacter, Pantoea and Serratia. The bioassays of supernatant extracts revealed that a portion of the strains have a remarkable AHL profile for AHL induction activity using the two different biosensors, and one compound in the active extract of a representative isolate, NTL223, corresponded to 3-oxo-hexanoyl-homoserine lactone. A large population size and diversity of bacteria capable of AHL-driven QS were found to cohabit on leaves, implying that cross-communication based AHL-type QS may be common in the phyllosphere. Furthermore, this study provides a general snapshot of a potential valuable application of AHL-producing bacteria inhabiting leaves for their presumable ecological roles in the phyllosphere.     

深圳市显著排放VOCs的园林植物调查与分析

对深圳地区的主要园林树种、地带性植被的代表种共计158种植物释放的生物源的挥发性有机物（biogenic volatileorganic compounds,BVOCs）采用流动式、封闭式采样法采样,运至美国进行GC-MS分析测量.结果表明,短穗鱼尾葵（Caryotamitis）、海红豆（Adenanthera pavonina var.microsperma）、杧果（Mangifera indica）、海漆（Excoecoria agalloch）等31种植物具有释放异戊二烯的能力;另有鸡蛋果（Passiflora edulis）、小琴丝竹（Bambusa glaucescens cv.silverstripe）、山苍子（Litsea cubeba）、大型双子铁（Dioon spinulosum）等52种植物具有释放单萜烯类化合物的能力.对红树植物的测量表明,该类植物普遍具有释放单萜烯的能力.上述结果为建立深圳及周边地区的环境质量模型提供了重要数据,同时也可为我国热带亚热带城市大面积绿化以及经济林、生态林和防护林等的树种选择提供参考.