The researchers used comparative mass spectrometry analyses of the plant metabolites and the frass of the caterpillars that had fed on these plants. Therefore, the key questions for us were: Can we isolate the components and prove their structure, and, most importantly: Can we show from which specialized signaling pathways they originate and what function they have?" first author Sven Heiling summarizes the initial questions of the study. However, we found that they shared structural features of two plant defense compounds. "We were able to identify previously unknown chemical substances in the caterpillars' frass. The study is based on chemical analyses of caterpillar frass. They showed that larvae of the tobacco hawkmoth Manduca sexta are able to use two different plant defenses to counteract the harmful effect of the other. Researchers from the Max Planck Institute for Chemical Ecology in Jena, Germany, have now come across such an unexpected effect when studying defense mechanisms in the wild tobacco Nicotiana attenuata. However, many drug package inserts point out that there can be interactions between different active ingredients, which can not only enhance the effect of a drug, but also weaken it or even cancel it out. Let us know how this access is important for you.In chemical pest control, but also in medical treatment of diseases, it is often recommended to rely on a combination therapy of different agents in order to achieve the best success. Many UC-authored scholarly publications are freely available on this site because of the UC's open access policies. The relative contribution of polysaccharides was highest in late spring and summer in the smallest particle size fraction characterized (< 180 nm). The recalcitrant factor showed little seasonal variability in its contribution to primary marine aerosol. An unquantified recalcitrant factor of highly thermally stable organics showed significant correlation with FTIR-measured alcohol groups, consistently the main organic functional group associated with sea spray aerosol.We hypothesize that this factor represents recalcitrant dissolved organic matter (DOM) in seawater and that by extension alcohol functional groups identified in marine aerosol may more typically represent recalcitrant DOM rather than biogenic saccharide-like material, contrary to inferences made in previous studies. Aerosol polysaccharide V sodium mass ratios were consistently higher in ambient air than in the artificially generated sea spray, and we hypothesize that this results from more rapid wet deposition of sodium-rich aerosol. Among these is a polysaccharide factor representing about 10 %-30% of the submicron organic aerosol mass. A positive matrix factorization (PMF) analysis identified several characteristic aerosol components in the TDCIMS mass spectra. Samples were analyzed by Fourier transform infrared spectroscopy (FTIR), extracted into water, and analyzed by offline thermal desorption chemical ionization mass spectrometry (TDCIMS) and ion chromatography (IC). Size-segregated discrete aerosol filter samples were collected at sea in the North Atlantic from both ambient aerosol and artificially generated primary sea spray over four cruises timed to capture the seasonal phytoplankton bloom dynamics. We report results from a novel approach to characterize and quantify organic components of the marine aerosol. The composition of organic compounds in marine aerosols and the relative contributions of primary and secondary organic compounds remain uncertain.
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