Isotope ratio analysis by HRGC-MS of monoterpene hydrocarbons from citrus essential oils

The isotope ratio of monoterpene hydrocarbons in citrus essential oils of different origins was measured by ordinary high-resolution gas chromatography-mass spectrometry (HRGC-MS). The isotope ratio (Ir) was determined by the ratio of the isotope peak intensity (m/z 137) to the molecular mass peak intensity (m/z 136) of the monoterpene hydrocarbons. The accuracy of Ir was examined by measuring monoterpene hydrocarbon standards and 13C-labeled compounds. The isotope fingerprints based on the values of monoterpene hydrocarbons from lemon, lime and yuzu essential oils were determined. These citrus essential oils were also discriminated by a principal component analysis of their Ir data. The characteristic vectors showed that alpha-terpinene, beta-pinene and beta-phellandrene were important components for distinguishing between the citrus species. It is suggested that this technique will be applicable to evaluate the quality, genuineness and origin of citrus fruits and their products.     

MS fragment isotope ratio analysis for evaluation of citrus essential oils by HRGC-MS

To evaluate the origin of citrus essential oils, the isotope ratio of fragment peaks on HRGC-MS of the volatile compounds from various citrus oils was measured. The MS fragment ratio was found by the ratio of fragment peak intensity, m+1/m (m/z). This ratio reflects the isotope effect of volatile compounds, that is, it provides information about locality, quality, and species for essential oils. Multivariate analysis based on the MS fragment ratio of monoterpene hydrocarbons clearly distinguished three citrus species, yuzu, lemon, and lime. The carbonyl fractions were also extracted from citrus essential oils by the sodium hydrogensulfite method. The isotope ratio of MS fragments of octanal, nonanal, and decanal was also examined. The results suggest that there was no significant difference in the individual fragment isotope ratios of the three aldehydes.     

Biosynthesis of monoterpene hydrocarbons by isolated chromoplasts from daffodil flowers

Incubation studies using [1-14C]isopentenyl diphosphate and [1-2H2]isopentenyl diphosphate as substrates revealed that isolated chromoplasts from flowers of Narcissus pseudonarcissus L. are able to synthesize monoterpene hydrocarbons and linalool in high yields. The enzymes involved are soluble in the chromoplast stroma. It is hypothesized that in the plant cell plastids are the site of monoterpene biosynthesis, whereas the formation of sesquiterpenes may be restricted to the cytoplasm/endoplasmic reticulum.     

A comparative study of Scalesia species (Asteraceae) by gas chromatographic analysis of the monoterpene hydrocarbons of their essential oils

ADSERSEN, A. & SVENDSEN, A. B., 1986. A comparative study of Scalesia species (Asteraceae) by gas chromatographic analysis of the monoterpene hydrocarbons of their essential oils. The monoterpene hydrocarbons of the essential oils of 13 species of Scalesia , Asteraceae, endemic to the Galapagos Islands, were analysed by gas chromatography to determine whether the composition of these compounds could show any characteristics for the various species. Marked differences in the monoterpene hydrocarbon patterns of the Scalesia species investigated were observed. Whereas a-pinene was usually found in amounts of 30–50%, Scalesia villosa contained only 12%. Sabinene usually occurred in amounts of 10-1.5%, but S. divisa and S. affinis contained about twice as much. The limonene content was usually less than 1%, but S. microcephala, S. baurii and S. affinis contained amounts varying from about 2% to 9.5%.     

Effects of several variable factors on the isotope ratio by HRGC-MS

In the isotope ratio (Ir) analysis using GC-MS, several variable factors in sampling incidental to any food analysis were investigated for yuzu fruit. The Irs of ten monoterpene hydrocarbons in yuzu essential oils from each of six fruiting positions of three trees were measured. The sign test following t-test of all the Ir values demonstrated that there was no significant difference between both sampling years of 2001 and 2002. There was also no significant variation in the Ir values among the three trees and six fruiting positions in the individual two years.     

Allotetraploid hybrids between citrus and seven related genera produced by somatic hybridization

We have developed an efficient protoplast-fusion method to produce somatic hybrid allopolyploid plants that combine Citrus with seven related genera, including four that are sexually incompatible. In this paper we report the creation of 18 new allotetraploid hybrids of Citrus, including ten among sexually incompatible related genera, that may have direct cultivar potential as improved citrus rootstocks. All hybrids were confirmed by cytological and RAPD analyses. If fertile, the attributes of these hybrids may be amenable to further genetic manipulation by breeding at the tetraploid level. Wide somatic hybridization of Citrus via protoplast fusion bypasses biological barriers to the natural allopolyploidization of Citrus, and creates new evolutionary opportunities that would be difficult or impossible to achieve by natural or conventional hybridization.Florida Agricultural Experiment Station Journal Series No. R-04520     

Classification of Aristolochia species based on GC-MS and chemometric analyses of essential oils

Essential oils were obtained from roots of 10 Aristolochia species by hydrodistillation and analysed by GC-MS. A total of 75 compounds were identified in the analysed oils. Multivariate analyses of the chemical constituents of the roots enabled classification of the species into four morphological groups. These forms of analysis represent an aid in identification of further specimens belonging to these species.     

Testing the role of cuticular hydrocarbons on intercolonial agonism in two subterranean termite species (Coptotermes) and their hybrids

Recognition of nestmates is an important function in many social insects, as it maintains colony integrity by preventing outsiders from entering the colony. Agonism usually results from the interaction of con-specific non-nestmate individuals in termite colonies. Previous studies hypothesized that the cuticular hydrocarbon (CHC) profile of individuals had a role in nestmate recognition. However, contradictory results from previous studies in some subterranean termites raise questions on the validity of the cuticular hydrocarbon hypothesis. In the current study, Coptotermes gestroi (Wasmann), Coptotermes formosanus Shiraki and their hybrids were reared in identical conditions from colony foundation. This approach eliminates sources of variability in their cuticular hydrocarbon profiles aside from a genetic component. The parental species displayed dissimilar profiles of predominant alkanes and methyl alkanes, but both hybrid types displayed an overlapping, intermediate profile of these CHC. The mixture of the most abundant CHCs alone did not determine kin recognition; while the two hybrid types’ CHC profiles converged, the hybrids still showed strong agonism. One of the hybrid mating types easily merged with C. formosanus, despite only partial genetic similarity and dissimilar cuticular profiles for the common alkanes and methyl alkanes. This study suggests that in Coptotermes termites, the variable abundance of the major alkanes and methyl alkanes commonly found in most Coptotermes species does not explain agonistic patterns, and that other factors such as possibly more complex but less abundant CHC are likely to be involved in colonial recognition.

     

Seasonal differences in isoprene and light-dependent monoterpene emission by Amazonian tree species

Whereas for extra‐tropical regions model estimates of the emission of volatile organic compounds (VOC) predict strong responses to the strong annual cycles of foliar biomass, light intensity and temperature, the tropical regions stand out as a dominant source year round, with only little variability mainly due to the annual cycle of foliar biomass of drought‐deciduous trees. As part of the Large Scale Biosphere Atmosphere Experiment in Amazônia (LBA‐EUSTACH), a remote secondary tropical forest site was visited in the dry‐to‐wet season transition campaign, and the trace gas exchange of a strong isoprene emitter and a monoterpene emitter are compared to the wet‐to‐dry season transition investigations reported earlier. Strong seasonal differences of the emission capacity were observed. The standard emission factor for isoprene emission of young mature leaves of Hymenaea courbaril was about twofold in the end of the dry season (111.5 μgC g^?1 h^?1 or 41.2 nmol m^?2 s^?1) compared to old mature leaves investigated in the end of the wet season (45.4 μgC g^?1 h^?1 or 24.9 nmol m^?2 s^?1). Standardized monoterpene emission rate of Apeiba tibourbou were 2.1 and 3.6 μgC g^?1 h^?1 (or 0.3 and 0.8 nmol m^?2 s^‐1), respectively. This change in species‐specific VOC emission capacity was mirrored by a concurrent change in the ambient mixing ratios. The growth conditions vary less in tropical areas than in temperate regions of the world, and the seasonal differences in emission strength could not be reconciled solely with meteorological data of instantaneous light intensity and temperature. Hence the inadequacy of using a single standard emission factor to represent an entire seasonal cycle is apparent. Among a host of other potential factors, including the leaf developmental stage, water and nutrient status, and abiotic stresses like the oxidative capacity of the ambient air, predominantly the long‐term growth temperature may be applied to predict the seasonal variability of the isoprene emission capacity. The dry season isoprene emission rates of H. courbaril measured at the canopy top were also compared to isoprene emissions of the shade‐adapted species Sorocea guilleminiana growing in the understory. Despite the difference in VOC emission composition and canopy position, one common algorithm was able to predict the diel emission pattern of all three tree species.     

Characterization of Gypsophila species and commercial hybrids with nuclear whole-genome and cytoplasmic molecular markers

The genus Gypsophila contains about 150 annual and perennial flowering plant species native to the temperate regions of Europe and Asia. Nowadays Gypsophila species are present worldwide as garden ornamental plants. Although Gypsophila is one of the most economically important ornamental crops, little is known about its genetic variability and the relationships among the different wild species, cultivars, and commercial hybrids. The aim of our work was to analyze genetic distances among 5 wild species and 13 commercial hybrids of Gypsophila with similar phenotypes but unknown origin. For this purpose, we have used amplified fragment length polymorphism, target region amplification polymorphism, and inter simple sequence repeat whole-genome markers and chloroplast simple sequence repeat (cpSSR), targeting chloroplast DNA. Nuclear markers were found to distinguish all the analyzed samples while cpSSR markers were found to discriminate the different wild species, but could not sufficiently separate the commercial hybrids. This notwithstanding, the data obtained allowed us to cluster the commercial hybrids into different sub-groups and to determine the relationships with the putative species of origin.     

Annual rainfall does not directly determine the carbon isotope ratio of leaves of Eucalyptus species

Leaf carbon isotope discrimination (delta13C) was widely considered to directly reflect the rainfall environment in which the leaf developed, but recent observations have queried this. The relationship between delta13C and rainfall was explored in Eucalyptus species growing along a rainfall gradient in Australia. The leaves of 43 species of Eucalyptus and the closely related Corymbia species produced in 2003 were sampled in September 2004 at 50 sites and grouped into 15 locations along a rainfall gradient in southwest Western Australia. At 24 sites, the same species and same trees were sampled as in a study in September 2003 when leaves produced in 2002 were sampled. The rainfall in 2004 was on average 190 mm (range 135-270 mm) higher at all locations than in 2003. In the leaves sampled in 2004, the mean carbon isotope discrimination (delta13C) across the 15 locations decreased 2.9 per thousand per 1000 mm of rainfall, the specific leaf area (SLA) increased by 2.9 m2 kg(-1) per 1000 mm of rainfall and the nitrogen (N) content decreased by 1.56 g m(-2) per 1000 mm of rainfall. In contrast, a comparison between the leaves produced in the drier 2002 year compared with the wetter 2003 year showed that there was a strong correlation (r2= 0.85) between the SLA values between years and a trend for higher values with increasing SLA, but the values of delta(13)C were on average only 0.38 per thousand lower (more negative) at all locations in the wetter year, equivalent to a decrease of 2.0 per thousand per 1000 mm of rainfall. The results suggest that while there may be constitutive differences in leaf morphology, SLA and N content per unit area, increasing rainfall or cloudiness associated with higher rainfall increases SLA and decreases N content per unit area. We conclude that rainfall does not directly influence delta13C, but induces leaf morphological and physiological changes that affect the resultant delta13C.     

Isotope ratio by HRGC-MS of citrus Junos tanaka (yuzu) essential oils: m/z 137/136 of terpene hydrocarbons

The isotope ratios of monoterpene hydrocarbons in Citrus junos Tanaka (yuzu) essential oils from different origins were determined by ordinary high-resolution gas chromatography-mass spectrometry (HRGC-MS). Both intensities of the molecular mass peaks (m/z 136) and of the isotope peaks (m/z 137) of monoterpene hydrocarbons were measured by single-ion monitoring with an MS analysis. The isotope ratios (m/z 137/136) of the ten monoterpene hydrocarbons commonly contained in citrus essential oils, alpha-pinene, beta-pinene, sabinene, myrcene, alpha-phellandrene, alpha-terpinene, limonene, gamma-terpinene, beta-phellandrene and terpinolene, were determined in yuzu samples of the highest commercial quality from 42 different production districts. Statistical treatment of these data by the t-test and sign test revealed significant differences of the isotope effects in each yuzu sample. It is suggested that this technique will be applicable for evaluating the quality, genuineness and origin of citrus fruits and their products. The isotope fingerprints were also demonstrated in several citrus fruits other than the yuzu samples.     

Characterization of Aspergillus species based on fatty acid profiles

Cellular fatty acid (FA) composition was utilized as a taxonomic tool to discriminate between different Aspergillus species. Several of the tested species had the same FA composition and different relative FA concentrations. The most important FAs were palmitic acid (C16:0), estearic acid (C18:0), oleic acid (C18:1) and linoleic acid (C18:2), which represented 95% of Aspergillus FAs. Multivariate data analysis demonstrated that FA analysis is a useful tool for differentiating species belonging to genus Aspergillus. All the species analyzed showed significantly FA acid profiles (p < 0.001). Furthermore, it will be possible to distinguish among Aspergillus spp. in the Flavi Section. FA composition can serve as a useful tool for the identification of filamentous fungi.     

Cytological observations on some species and hybrids ofVaccinium

Summary Meiosis was studied inVaccinium myrtillus (n=12),V. vitis-idaea (n=12),V. myrtillus ×vitisidaea (n=12), colchicine-induced tetraploidV. myrtillus (n=24),V. uliginosum (n=24), the cultivated blueberry varieties Rancocas and Pemberton (n=24), and the hybridsV. uliginosum × Rancocas andV. uliginosum × Pemberton (n=24). Pairing was regular in the diploid species. Some multivalent formations occurred inV. uliginosum and in the cultivated blueberry varieties and to a considerable extent in the autotetraploidV. myrtillus. The spontaneous diploid hybridV. myrtillus ×vitis-idaea displayed numerous meiotic irregularities, whereas the artificial hybrids betweenV. uliginosum and cultivated blueberry showed relatively regular meiosis. Pairing relationships of the various genomes are discussed. Breeding programs for the use of North-European species with American cultivated blueberry varieties are discussed in the light of the cytological observations.

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Zusammenfassung Die diploiden (n=12) ArtenVaccinium myrtillus, V. vitis-idaea, V. myrtillus×vitis-idaea und die tetraploiden (n=24)V. myrtillus (Colchicin-induziert) undV. uliginosum sowie die kultivierten amerikanischen Blaubeersorten Rancocas und Pemberton (n=24) und die HybridenV. uliginosum×Rancocas undV. uliginosum×Pemberton wurden cytologisch untersucht. In den diploiden Arten war die meiotische Chromosomenpaarung regelmäßig. Multivalente traten in geringerem Umfange beiV. uliginosum und kultivierten Blaubeersorten, viel stärker aber in der autotetraploidenV. myrtillus auf. Die spontane diploide HybrideV. myrtillus×vitis-idaea zeigte zahlreiche meiotische Störungen, die künstlichen Hybriden zwischenV. uliginosum und der kultivierten amerikanischen Blaubeere hatten demgegenüber eine relativ regelmäßige Meiose. Die Paarungsverhältnisse der verschiedenen Genome werden diskutiert. Auf Grund der cytologischen Beobachtungen wird ein Züchtungsprogramm für nordeuropäischeVaccinium-Arten zusammen mit amerikanischen Kultursorten erörtert.

     

Profiling of urinary formestane and confirmation by isotope ratio mass spectrometry

Formestane (F, androst-4-en-4-ol-3,17-dione) is an irreversible aromatase inhibitor with the ability to suppress the estrogen production from anabolic steroids. Consequently, F is mentioned on the World Anti-Doping Agency (WADA) prohibited list and because studies have shown that F is produced endogenously in small amounts, a threshold for urinary excreted F of 150 ng/mL was introduced. Lower concentrations could be due to endogenous production and need further investigation to prove the exact origin through determination of the carbon isotope ratio.However, because the current screening methods are a lot more sensitive, F is detected in practically every urine sample. A strict implementation of this WADA rule would imply that almost every urine sample needs additional investigation to verify an exogenous or endogenous origin. The main aim of this study was to propose and introduce a lower concentration limit of 25 ng/mL beneath which the detected F is considered as being endogenous and no further investigation is needed. The data presented in this paper suggests that this threshold provides a good balance between a sufficiently large detection window and not having to perform isotope ratio mass spectrometry (IRMS) analyses on negative urine samples.     

不动杆菌属(Acinetobacter)细菌降解石油烃的研究进展

不动杆菌属细菌分布广泛,作为重要的石油烃降解者,在乳化和降解石油烃、降低石油烃生物毒性等方面有重要作用。本文概述了不动杆菌属细菌对烷烃、芳香烃等石油烃组分的降解,总结了该属细菌中已发现的烷烃氧化酶和芳香烃氧化酶,综述了该属细菌所分泌的表面活性剂的类型和乳化机理,讨论了固定化对该属细菌降解石油烃的影响,展望了该属细菌降解石油烃的应用前景。基于此,作者认为探索不动杆菌属细菌降解石油烃的详细机理和途径、发现关键酶、寻找遗传工具、构建基因工程菌、发掘环境友好的固定化材料,应是未来的研究重点及热点。