Volatile compound diversity and conserved alarm behaviour in Triatoma dimidiata

Background: Triatoma dimidiata (Latreille) is a key vector complex of Trypanosoma cruzi, etiologic agent of Chagas disease, as it spans North, Central, and South America. Although morphological and genetic studies clearly indicate existence of at least five clades within the species, there has been no robust or systematic revision, or appropriate nomenclature change for species within the complex. Three of the clades (haplogroups) are distributed in Mexico, and recent evidence attests to dispersal of clades across previously "presumed"monotypic geographic regions. Evidence of niche conservatism among sister species of this complex suggests that geographic dispersal is possible for non-sympatric populations, although no information is available on the behavioural aspects of potential interclade interactions, for instance whether differentiation of chemical signaling or response to these signals could impede communication among the haplogroups. Methods: Volatiles emitted by disturbed bugs, Brindley's (BGs), and metasternal (MGs) glands were identified using solid-phase micro-extraction (SPME) and gas chromatography coupled mass spectrometry (GC-MS). Volatile compounds emitted by BGs and MGs, and those secreted by disturbed nymphs and adults, of the three Mexican T. dimidiata haplogroups were tested for avoidance behaviour by conspecific nymphs and adults using an olfactometer. Results: Triatoma dimidiata haplogroups all have three age-related alarm responses: absence of response by early stage nymphs, stage-specific response by 4-5th stage nymphs, and a shared 4-5th nymph and adult response to adult compounds. Disturbed bugs released 15 to 24 compounds depending on the haplogroup, among which were three pyrazines, the first report of these organoleptics in Triatominae. Isobutyric acid from BGs was the most abundant molecule in the response in all haplogroups, in addition to 15 (h1) to 21 (h2 and h3) MG compounds. Avoidance behaviour of disturbed bugs and volatiles emitted by BGs were haplogroup specific, while those from the MG were not. Conclusions: Discriminant and cluster analysis of BG +MG compounds indicate significant separation among the three haplogroups, while alarm response compounds were similar between h2 and h3, both distinct from h1. This latter haplogroup is ancestral phylogenetically to the other two. Our results suggest that alarm responses are a conserved behaviour in the Triatoma dimidiata complex.Fil: May Concha, Irving Jesus. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentina. Instituto Nacional de Salud Pública; MéxicoFil: Rojas, Julio C.. El Colegio de la Frontera Sur; MéxicoFil: Cruz López, Leopoldo. El Colegio de la Frontera Sur; MéxicoFil: Ibarra-Cerdeña, Carlos N.. Instituto Politécnico Nacional. Centro de Investigación y de Estudios Avanzados; MéxicoFil: Ramsey, Janine. Instituto Nacional de Salud Pública; Méxic

Modeling-based determination of physiological parameters of systemic VOCs by breath gas analysis: a pilot study

In this paper we develop a simple two compartment model which extends the Farhi equation to the case when the inhaled concentration of a volatile organic compound (VOC) is not zero. The model connects the exhaled breath concentration of systemic VOCs with physiological parameters such as endogenous production rates and metabolic rates. Its validity is tested with data obtained for isoprene and inhaled deuterated isoprene-D5.Comment: 16 page

EFFECTS OF ORGANIC AND CONVENTIONAL N-FERTILIZATION ON QUALITY TRAITS IN CORIANDER (CORIANDRUM SATIVUM L.)

In organic cropping management of Medicinal and Aromatic Plants, the best quality expression is crucial to gain satisfactory incomes. Coriander (Coriandrum sativum L.) is an annual herbaceous plant with a commercial value due to the typical scent of its fruits (commonly termed “seeds”), rich in a pale yellow oil (1-2% in small-sized types, 0.2-0.5% in large-sized ones). Several studies have been done for determining the composition of volatile fraction of Coriander, which was found to vary also as a consequence of cropping techniques, including nitrogen fertilization. In order to gain useful information about the effects, if present at all, of organic N fertilization on Coriander quality in terms of volatiles composition pattern, a three-year trial (2004-2006) was carried out using different types and rates of organic and conventional N fertilizers. Volatile composition of fruits was obtained by means of GC-MS and data were evaluated by multivariate statistical analysis. The most representative compound are linalool, followed by camphor, geranyl acetate and geraniol. The group partition was mainly due to different quantitative ratio of compounds; the differences in volatile composition, however, followed a scheme more resembling the cropping year than the fertilization management

Determination of urban volatile organic compound emission ratios and comparison with an emissions database

During the NEAQS-ITCT2k4 campaign in New England, anthropogenic VOCs and CO were measured downwind from New York City and Boston. The emission ratios of VOCs relative to CO and acetylene were calculated using a method in which the ratio of a VOC with acetylene is plotted versus the photochemical age. The intercept at the photochemical age of zero gives the emission ratio. The so determined emission ratios were compared to other measurement sets, including data from the same location in 2002, canister samples collected inside New York City and Boston, aircraft measurements from Los Angeles in 2002, and the average urban composition of 39 U.S. cities. All the measurements generally agree within a factor of two. The measured emission ratios also agree for most compounds within a factor of two with vehicle exhaust data indicating that a major source of VOCs in urban areas is automobiles. A comparison with an anthropogenic emission database shows less agreement. Especially large discrepancies were found for the C2-C4 alkanes and most oxygenated species. As an example, the database overestimated toluene by almost a factor of three, which caused an air quality forecast model (WRF-CHEM) using this database to overpredict the toluene mixing ratio by a factor of 2.5 as well. On the other hand, the overall reactivity of the measured species and the reactivity of the same compounds in the emission database were found to agree within 30%. Copyright 2007 by the American Geophysical Union

Combustive approach for measuring total volatile phosphorus content in landfill gas

A technique was developed to measure the total gaseous phosphorus content in biogas. The amount of air needed for a neutral to oxidising flame was mixed with the biogas. The gas mixture was burnt in a closed quartz burner and the combustion gasses were bubbled through a nitric acid solution. The phosphate content in the bubbling liquid was determined with sector field ICP-MS. The technique was validated in the lab with phosphine. Afterwards the set-up was installed on a landfill. The total gaseous phosphorus content in the landfill gas, measured with the combustive technique, ranged from 1.65 to 4.44 mug P/m(3). At the same time the phosphine concentration in the landfill gas was determined gas chromatographically (GC). The phosphine (PH3) content measured with GC ranged from 7.6 to 16.7 mug PH3-P/m(3). Since the phosphine-P content (GC) was consistently higher than the total gaseous phosphorus content (burner/ICP-MS), the hypothesised presence of highly toxic gaseous phosphorus compounds other than phosphine could not be demonstrated

Mikroorganismen an Aesculus hippocastanum – olfaktorische Perspektive von Cameraria ohridella (Deschka & Dimic)

Since the 80s, the popular park- and city tree Aesculus hippocastanum has been infested with the leaf miner Cameraria ohridella (DESCHKA & DIMIC 1986). Additionally, the pathogenic fungi Guignardia aesculi causes leaf blotch disease and Erysiphe flexuosa causes powdery mildew on horse chestnuts. Often, all three diseases occur in parallel at the same leaves leading to a situation of competition. Moreover, recently some endophytic fungi were isolated from the leaf tissue of A. hippocastanum. In the present study, the volatile interaction between three trophic levels plant, insect, and fungi are discussed.Mikroorganismen an Aesculus hippocastanum – olfaktorische Perspektive von Cameraria ohridella (Deschka & Dimic) Seit den 80er Jahren wird die Gemeine Rosskastanie Aesculus hippocastanum durch den Minierer Cameraria ohridella (Lepidoptera, Gracillariidae) befallen. Außerdem wird die Rosskastanie durch den Blattbräunepilz Guignardia aesculi und den Mehltau Erysiphe flexuosa attackiert. Oft treten alle drei Organismen parallel am gleichen Blatt auf. Weiterhin konnten endophytische Pilze aus dem Blattgewebe isoliert werden. Im vorliegenden Beitrag wird die volatile Interaktion zwischen Pflanze, Mikroorganismen und Insekt diskutiert. Mit Hilfe der Gaschromatographie und gekoppelter Massenspektroskopie (GC-MS) wurden Duftproben gesunder und mit den pathogenen Pilzen G. aesculi und E. flexuosa gleichzeitig infizierter Blätter der Rosskastanie analysiert. Identifizierte Komponenten wurden elektrophysiologisch (EAG) an der Insektenantenne und in Verhaltensversuchen getestet. Mit den pathogenen Pilzen befallene Rosskastanienblätter geben 1-Octen-3-ol, 3-Octanon, ein Derivat von 2(5H)-Furanon, Nonanal und Decanal ab. C. ohridella war in der Lage, diese Substanzen zu detektieren. In Zweifachwahltests mit gesunden A. hippocastanum Zweigen reagierten Weibchen mit reduzierter Eiablage auf die Applikation von 1-Octen-3-ol, 3-Octanon, 2(5H)-Furanon und Decanal im Vergleich zur unbehandelten Kontrolle. Es ist bekannt, dass 1-Octen-3-ol und 3-Octanon von Pilzen selber emittiert werden. Nonanal und Decanal werden von Zellen, die nach Penetration durch Pilzhyphen unter oxidativem Stress stehen, produziert. Die Derivate von 2(5H)-Furanon wirken antimikrobiell und können auf einen Schutzmechanismus der Pflanze oder auf einen Konkurrenzmechanismus von Mikroorganismen um denselben Lebensraum hinweisen. Eine mögliche Erklärung wäre, dass diese Substanz von Endophyten zur Verteidigung des sie umgebenden Blattgewebes gegen die pathogenen Pilze produziert wird

Development of Head Space Sorptive Extraction Method for the Determination of Volatile Compounds in Beer and Comparison with Stir Bar Sorptive Extraction

A headspace sorptive extraction method coupled with gas chromatography-mass spectrometry (HSSE-GC-MS) was developed for the determination of 37 volatile compounds in beer. After optimization of the extraction conditions, the best conditions for the analysis were stirring at 1000 rpm for 180 min, using an 8-mL sample with 25% NaCl. The analytical method provided excellent linearity values (R-2 > 0.99) for the calibration of all the compounds studied, with the detection and quantification limits obtained being low enough for the determination of the compounds in the beers studied. When studying the repeatability of the method, it proved to be quite accurate, since RSD% values lower than 20% were obtained for all the compounds. On the other hand, the recovery study was successfully concluded, resulting in acceptable values for most of the compounds (80-120%). The optimised method was successfully applied to real beer samples of different types (ale, lager, stout and wheat). Finally, an analytical comparison of the optimised HSSE method, with a previously developed and validated stir bar sorptive extraction (SBSE) method was performed, obtaining similar concentration values by both methods for most compounds