Trends in floral scent chemistry in pollination syndromes: floral scent composition in moth-pollinated taxa

KNUDSEN, J. T. & TOLLSTEN, L., Trends in floral scent chemistry in pollination syndromes: floral scent composition in moth-pollinated taxa. Floral scent from 15 moth-pollinated species in nine families was collected by head-space adsorption. The chemical composition was determined by coupled gas chromatography-mass spectrometry (GC-MS). The typical floral scent of moth-pollinated flowers contains some acyclic terpene alcohols, their corresponding hydrocarbons, benzenoid alcohols and esters and small amounts of some nitrogen compounds. The floral scent composition of sphingophilous flowers can be distinguished from that of phalaenophilous flowers by the presence of oxygenated sesquiterpenes. The flowers of three of the studied species had the general appearance and floral scent composition of moth-pollinated flowers, but contained no nectar reward. These species probably rely on deceptive pollination by naive visitors, which are deceived by the similarity of the flowers' morphological and scent chemistry to that of rewarding moth flowers. The finding of similar or structurally closely related floral scent compounds in both temperate and tropical species from both the Old and New worlds suggests that floral scent composition has been selected by a specific group of pollinators, moths that have similar sensory preferences. The functions of floral scent in moth-pollinated flowers are discussed in relation to an often observed over-representation of male moth visitors.     

Floral scent in bat-pollinated plants: a case of convergent evolution

The chemical composition of floral scent in eight bat-pollinated species belonging to six different plant families was investigated. Floral scent was collected by headspace trapping using porous adsorbents and the chemical composition determined by coupled gas chromatography-mass spectrometry. In all species except one the floral scent was found to include sulphur-containing compounds, of which several are reported for the first time in floral scents. Three species contained mushroom-like smelling fatty acid derivatives with a C₈-skeleton. Such flowers may be recognized by pollinators as humid environments in otherwise dry surroundings. The presence of similar or chemically closely related sulphur containing compounds in floral scent of bat-pollinated plant species from differing families may represent a case of convergent evolution in scent composition and an adaptation to attract this specific group of pollinators with similar sensory preferences.     

The chemical nature of fetid floral odours in stapeliads (Apocynaceae-Asclepiadoideae-Ceropegieae)

By emitting strong fetid scents, sapromyiophilous flowers mimic brood and food sites of flies to attract them as pollinators. To date, intensive comparative scent analyses have been restricted to sapromyiophilous Araceae. Here, we analysed flower volatiles of fetid stapeliads to improve our understanding of the floral biology of fly pollinated species, and to learn whether mimicry types comparable to those found in Araceae exist. Floral volatiles of 15 species out of 11 genera within the Asclepiadoideae-Ceropegieae-Stapeliinae were collected via headspace adsorption and thermal desorption and analysed by gas chromatography-mass spectometry (GC-MS). Data were analysed using CNESS-NMDS statistics. Sapromyiophilous stapeliads are highly diverse in their scent composition, in which sulphur compounds, benzenoids, fatty acid derivatives or nitrogen-containing compounds dominate. Four groups are evident: species with high p-cresol content but low amounts of polysulphides (herbivore faeces mimicry); species with mainly polysulphides and low amounts of p-cresol (carnivore/omnivore faeces or carcass mimicry); species with high amounts of heptanal and octanal (carnivore/omnivore faeces or carcass mimicry); and species with hexanoic acid (urine mimicry). Considering the findings in the unrelated Araceae, our results support the universality of different mimicry types that are obviously subsumed under the sapromyiophilous syndrome.     

红芒6号果实成熟阶段香气成分研究

对商熟期及完熟期的红芒6号芒果果实采用顶空固相微萃取法(HS-SPME)提取香气成分,以气相色谱—质谱分析进行鉴定。共检出22种香气成分,其中商熟期14种,完熟期10种,主要为萜烯类、醛类、酸类等。两个阶段都具有的成分是α-桂叶烯、α-蛇麻烯等;商熟期主要的香气成分是( )-2-蒈烯;完熟期的主要香气成分是δ-3-蒈烯。     

古尼拟青霉和蝙蝠蛾拟青霉发酵菌丝体挥发性成分的分析与比较

对蝙蝠蛾拟青霉Paecilomyces hepiali和古尼拟青霉P. gunnii菌丝体的挥发性成分进行了研究,采用同时蒸馏萃取法分别提取两种菌丝体中的挥发性成分,经GC-MS联用仪对挥发性成分进行分离鉴定,分别分析出25种和32种挥发性成分。在蝙蝠蛾拟青霉菌丝体挥发性成分中2,6-二叔丁基对甲酚和1,5-二氢-1-甲基-2H-吡咯-2-酮相对含量较高,分别占65.78%和12.77%;在古尼拟青霉菌丝体中挥发性成分2,6-二叔丁基对甲酚和(E,E)-2,4-癸二烯醛相对含量较高,分别占62.11%和12.32%。两种菌丝粉共有8种共有成分,分别占蝙蝠蛾拟青霉挥发性成分的71.58%,古尼拟青霉挥发性成分的69.67%;由此可见蝙蝠蛾拟青霉和古尼拟青霉菌丝体主要挥发性物质的成分是相同的。通过对蝙蝠蛾拟青霉和古尼拟青霉挥发性成分的研究,为我们进一步了解这两种真菌菌丝体的药理作用提供了实验依据。     

GC-MS分析九头狮子草挥发油的化学成分

采用水蒸气蒸馏法提取九头狮子草挥发油,利用 GC-MS 联用技术,结合化学计量方法对其化学成分进行定性和定量分析,用面积归一法测定各组分的相对质量分数.结果表明：九头狮子草中挥发油主要由植酮(19．82％)、丁香油酚甲醚(3．96％)、β-石竹烯(3．75％)、肉豆蔻醚(3．08％)、3-甲基-2-(3,7,11-三甲基十二烷基)呋喃(3．64％)、2-戊基呋喃(2．73％)和氧化石竹烯(2．69％)等51种成分组成,占总量的98．82％.     

Pollinators,floral morphology and scent chemistry in the southern African orchid genus Schizochilus

Floral evolution often involves suites of traits, including morphology, colour and scent, but these traits are seldom analysed together in comparative studies. We investigated the associations between floral traits and pollination systems in Schizochilus, a southern African orchid genus with small nectar-producing flowers that has not been studied previously with respect to pollination biology. Field observations indicated the presence of distinct pollination systems in the four species which occur in the Drakensberg, including pollination by muscid flies in Schizochilus angustifolius, tachinid flies in Schizochilus zeyheri, various small flies in Schizochilus bulbinella and bees and wasps in Schizochilus flexuosus. Pollination success and pollen transfer efficiency clearly differed among the four species but were not correlated with the quantity of nectar rewards. Multivariate analysis of floral morphology and floral scent chemistry based on GC-MS data revealed significant differences among species as well as populations within species. The floral scent of S. angustifolius was dominated by the benzenoid compounds benzaldehyde and phenylacetaldehyde. Samples of one population of S. bulbinella were relatively similar to S. angustifolius but samples of another population were very distinct due to the occurrence of the nitrogen-containing compounds 3-methyl-butyl aldoxime (syn/anti) and the higher amounts of aliphatic esters, alcohols and acids. In contrast, the floral scent of S. flexuosus and S. zeyheri was characterized by high relative amounts of methyl benzoate. We conclude that Schizochilus has distinct, specialized pollination systems associated with subtle but significant variation in floral morphology and scent chemistry. We also caution that sampling of several populations may be required to characterize floral scent composition at the species-level in plants.     

Comparison of gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry methods to quantify alpha-tocopherol and alpha-tocopherolquinone levels in human plasma.

Two mass spectrometric methods were established for the quantitative analyses of alpha-tocopherol (TH) and its oxidation product alpha-tocopherolquinone (TQ) in human plasma. Both methods make use of isotopically labeled internal standards of different levels of deuteration (d3-TH and d6-TQ). Plasma (100 microl) was saponified in the presence of a mixture of antioxidants, and then TH and TQ were extracted with hexane. With the GC-MS method, the analytes were first converted into O-trimethylsilyl derivatives before analysis in the selective ion monitoring mode. The derivatization procedure led to the quantitative conversion of TQ into the O-trimethylsilyl derivative of tocopherolhydroquinone, giving rise to a more stable molecule with less fragmentation than for TQ. The increased stability of the molecule resulted in an enhanced contribution of the base peak to the total observed ions and therefore an increased sensitivity of the base peak for quantification. With the liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, TH and TQ were detected by multiple reaction monitoring after positive electrospray ionization. The GC-MS and LC-MS/MS methods showed nearly the same accuracy (>95%) and the same within-day precisions, with less than 5 and 10% for TH and TQ, respectively. The between-day precision and the limit of quantification for TQ in plasma were better by LC-MS/MS (4%; 3 nM) than by GC-MS (21%; 10 nM). Analysis and method validation were carried out with plasma samples obtained from a male volunteer pre- and postexercise. Both techniques showed that the ratio of TQ/TH was elevated by 35% immediately after exercise and had returned to basal levels when measured 24 h later.     

燕山山脉一种香料型乳菇的香味成分分析

利用固相微萃取技术（SPME）偶联气相色谱-质谱（GC-MS）分析燕山山脉一种香料型乳菇——香亚环乳菇Lactarius subzonarius的挥发性成分。共检出25种挥发性成分,其中氧杂环化合物3种、醛类1种、酯类13种、烯烃类3种、芳香族化合物2种和烷烃类3种。具有葫芦巴感官气味的挥发性组分3-羟基-4,5-二甲基-2(5H)-呋喃酮的相对含量35.76%,该成分是其近缘种Lactarius helvus的主要香味化合物,故推测3-羟基-4,5-二甲基-2(5H)-呋喃酮是其关键香味成分。     

一株有色金属矿山1-亚硝基-2-萘酚降解菌的筛选、鉴定和降解特性

1-亚硝基-2-萘酚是一类有色选矿药剂代表性的新型浮选药剂,在采选冶行业为了提高低品位矿物资源的利用率,被大量投入使用,该药剂的高稳定性进一步增大了矿山环境中重金属与有机选冶药剂复合污染的治理难度。微生物修复作为稠环芳烃(polycyclic aromatic hydrocarbons,PAHs)类污染物重要技术手段之一,具有安全、经济、高效和无二次污染等特点。【目的】本研究从我国广西河池市周边的典型有色金属尾矿环境中分离出1株高效降解1-亚硝基-2-萘酚的菌株,并分析其降解特性及其潜在的代谢途径,从而探究矿山复合污染生态系统中稠环芳烃类污染物的微生物修复技术的应用前景。【方法】从有色金属尾矿样本中筛选到以1-亚硝基-2-萘酚为唯一碳源的菌株,经16S rRNA基因序列鉴定,结合气相色谱-质谱联合(gas chromatography-mass spectrometer,GC-MS)检测分析菌株对1-亚硝基-2-萘酚的降解特性及中间代谢产物,并推测可能的代谢途径。【结果】筛选获得1株高效降解1-亚硝基-2-萘酚的Pseudomonas putida CUGB-JL11菌株,经鉴定为革兰氏阴性杆的恶臭假单胞菌。该菌株最适温度为30 ℃左右,最适pH值范围为6-8条件下,菌株5 d内对40 mg/L 1-亚硝基-2-萘酚的降解率高达81%。降解中间代谢产物主要为苯环类物质：苯甲羟肟酸甲酯和苯丙胺,但其母体及大部分中间产物都降解为小分子物质或者被完全降解。【结论】恶臭假单胞菌P. putida CUGB-JL11具有良好的1-亚硝基-2-萘酚降解能力和较强的环境适应性,有进一步被开发为微生物菌剂以用于稠环芳烃类污染修复的巨大潜力,为有色金属矿山生态系统中重金属和有机选冶药剂复合污染的微生物修复研究提供了理论依据和可利用的微生物资源。     

固相微萃取—气相色谱—质谱联用分析蓼实挥发性成分

察了萃取样品温度、萃取纤维吸附时间等因素对于固相微萃取蓼实挥发性成分的影响,确定较佳的实验条件为：萃取样品温度60℃,萃取纤维吸附时间60 min,脱附温度250℃,脱附时间5 min。用气相色谱—质谱联用技术测定上述条件所得蓼实挥发性化学成分,并鉴定出其中43种,占总峰面积的76.73%。其中含量较高的物质有：罗汉柏烯 (6.99%),丁香烯 (5.59%),2,5,5,8 a-四甲基-6,7,8,8a 四氢-5H-萘-1-酮(5.52%),α-丁香烯(4.29%),1,2,4a,5,6,8a-六氢-4,7-二甲基-1-异丙基萘(4.04%),环氧石竹烯(3.60%),α-香附酮(3.54%),4,5,5a,6,6a,6b-6氢-4,4,6b-三甲基-2-乙烯基-2H-环丙香豆酮(3.54%),香叶基丙酮(3.48%)。     

Synthesis of dehydrosqualene in microsomal fraction of Saccharomyces cerevisiae.

When the microsomal fraction of Saccharomyces cerevisiae was incubated with farnesyl pyrophosphate or presqualene pyrophosphate in the presence of Mn²⁺, dehydrosqualene was formed. Incubation of the reaction mixture in the presence of NADPH gave squalene, not dehydrosqualene, as the product. Little dehydrosqualene was formed when Mn²⁺ was replaced with Mg²⁺. These observations suggest that dehydrosqualene formation is closely associated with squalene synthesis in yeast, which synthesizes neither carotenes nor related pigments.     

冠突曲霉 veA基因缺失型与野生型的差异代谢物研究

为了鉴定冠突曲霉 veA基因缺失型与野生型的差异代谢物,寻找与 veA 基因产孢相关的代谢物,采用气相色谱-质谱联用（GC-MS）的代谢组学技术,分别收集2个菌株培养48h的菌丝体,经液氮研磨、超声萃取、三甲基氯硅烷衍生化后上机检测,将GC-MS检测的数据进行前处理和代谢物注释,并用统计学相关软件进行差异物筛选和相关性分析。结果显示,共鉴定99种代谢物,其中差异代谢物41种,野生型菌株中表达上调的显著差异代谢物有20种, veA缺失型菌株中表达上调的显著差异代谢物有21种,并预测差异代谢物的相关性,发现与623种代谢物产生相关性,其中313种呈正相关,310种呈负相关。筛选出来的差异代谢物涉及有机酸、氨基酸、碳水化合物、醇类、脂肪酸类等多种代谢物质,其中有机酸和氨基酸类代谢物占主导地位。本研究结果为进一步研究冠突曲霉代谢物与产孢的关联提供了一定的理论基础。     

Non-volatile floral oils of Diascia spp. (Scrophulariaceae)

The floral oils of Diascia purpurea, Diascia vigilis, Diascia cordata, Diascia megathura, Diascia integerrima and Diascia barberae (Scrophulariaceae) were selectively collected from trichome elaiophores. The derivatized floral oils were analyzed by gas chromatography-mass spectrometry (GC-MS), whilst the underivatized samples were analysed by electrospray ionization mass spectrometry (ESI-MS) and Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS). The most common constituents of the floral oils investigated are partially acetylated acylglycerols of (3R)-acetoxy fatty acids (C(14), C(16), and C(18)), as was proven with non-racemic synthetic reference samples. The importance of these oils for Rediviva bees is discussed in a co-evolutionary context.     

Determination of S-phenylmercapturic acid by GC-MS and ELISA: a comparison of the two methods

Abstract

S-phenylmercapturic acid (PMA) is a specific urinary biomarker of benzene at exposure levels lower than 1?ppm. However, measuring PMA in urine is an expensive task by either GC or HPLC due to the necessity of extensive sample pretreatment. In the present study, a commercial chemiluminescence enzyme-linked immunosorbent assay (ELISA) test for PMA and GC-MS were used for screening urine samples of 60 workers employed in petrochemical settings. The ELISA results were evaluated by comparison with the GC-MS. Overall, the ELISA test proved sensitive (limit of detection?=?0.1?µg?l^?1), rapid, robust and reliable, affording results in good agreement with the GC-MS (54% of measurements) and no false-negatives. On the other hand, 46% of the ELISA assays were assigned as false-positives (arbitrarily established when ELISA >5?µg?l^?1, GC-MS <5?µg?l^?1) and a correlation coefficient of 0.687 was calculated between the two methods. It appears that urinary PMA routine biomonitoring on large numbers of samples is carried out in a cost-effective and rapid approach by preliminary screening with the ELISA assay followed by GC-MS confirmation of concentrations exceeding the biological exposure index for PMA.     

固相微萃取结合GC/MS联用技术研究野松茸干品的挥发性成分

采用顶空固相微萃取结合气相色谱-质谱联用技术分析鉴定了野松茸干品中的挥发性风味成分.鉴定出48种风味化合物,占挥发性成分总量的91.44％,其中酸类9种、酯类6种、含氮杂环化合物11种、醇类3种、醛类5种、酮类10种、其他类4种.野松茸干品中主要的芳香成分是桂酸甲酯(42.99％)、3-甲基丁酸(8.56％)、2,6-二甲基吡嗪(8.36％)、2,5-二甲基吡嗪(2.46％)和1-辛烯-3-醇(2.06％).     

三株亚肉座菌乙酸乙酯提取物生物活性及GC-MS分析

采用乙酸乙酯提取3株亚肉座菌菌丝体,测试虫生真菌乙酸乙酯提取物（EAE）的抗肿瘤、抗菌和抗氧化活性,并借助GC-MS方法分析各提取物中的化学成分。结果发现2株亚肉座菌的菌丝体EAE对HepG2细胞的抑制活性较强,IC₅₀均小于9μmol/L;抗菌结果表明2株真菌的提取物具有抑制细菌生长的作用;1株供试菌的EAE表现出较强的DPPH自由基清除活性（清除率可达85%）。GC-MS分析表明从亚肉座菌JXJG201717、JXJG201720和ARSEF7697的EAE中分别鉴定出21、35和39种成分,主要成分为酯类、醇类和酸类;盘状亚肉座菌JXJG201720与ARSEF7697有相同化合物13个,与暹罗亚肉座菌JXJG201717存在7个相同化合物。本研究表明虫生亚肉座菌具有产生丰富活性成分的能力,彰显出多种利用价值。     

Morphology and chemical composition of metathoracic scent glands in Dolycoris baccarum (Linnaeus, 1758) (Heteroptera: Pentatomidae)

One of the general defining characters of the Heteroptera is the presence of metathoracic scent glands (MTG). Using scanning electron microscopy, the morphology of the MTG of Dolycoris baccarum (Linnaeus 1758) (Heteroptera: Pentatomidae) was studied. The MTG belong to the diastomian type. The two glandular pores located between the mesothoracic and metathoracic coxae are associated with 'mushroom-like' structures. The MTG are composed of a reservoir and a pair of lateral glands is connected to the reservoir by a duct. A groove-like structure extends downwards from the ostiole. While this structure is long and wide, its ostiole is oval. Extracts of the volatile fractions from male and female MTG secretions were analysed by capillary gas chromatography–mass spectrometry (GC-MS) and exhibited a typical pentatomid composition. Seventeen chemical compounds were detected in female secretions, whereas 13 chemical compounds were detected in the male secretions. Most chemical compounds were similar between the sexes but were different in their quantities. In this regard, the compounds identified were investigated and the biological functions of the glandular secretions were discussed. In the analyses of the MTG of females of D. baccarum , tridecane (50.97%) was a major odour component and (Z,Z)-4,16-octadecadien-1-ol acetate (0.02%) was a minor odour component. In males, tridecane (50.80%) was a major odour component and 1,2-benzenedicarboxylic acid (0.02%) was a minor odour component.