Post-mortem volatiles of vertebrate tissue

Volatile emission during vertebrate decay is a complex process that is understood incompletely. It depends on many factors. The main factor is the metabolism of the microbial species present inside and on the vertebrate. In this review, we combine the results from studies on volatile organic compounds (VOCs) detected during this decay process and those on the biochemical formation of VOCs in order to improve our understanding of the decay process. Micro-organisms are the main producers of VOCs, which are by- or end-products of microbial metabolism. Many microbes are already present inside and on a vertebrate, and these can initiate microbial decay. In addition, micro-organisms from the environment colonize the cadaver. The composition of microbial communities is complex, and communities of different species interact with each other in succession. In comparison to the complexity of the decay process, the resulting volatile pattern does show some consistency. Therefore, the possibility of an existence of a time-dependent core volatile pattern, which could be used for applications in areas such as forensics or food science, is discussed. Possible microbial interactions that might alter the process of decay are highlighted

Interactions of the indigenous evergreen shrub Sabina vulgaris with coexisting species in the Mu Us sandland

Facilitation is widespread in plant communities and particularly common in highly stressful environments. In the semi-arid Mu Us sandland where soil water and nutrients are short and grazing is heavy, many species grow within the large patches formed by the dense individuals of the unpalatable clonal shrub Sabina vulgaris, the only natural evergreen shrub species in the Mu Us sandland. However, the interactions between S. vulgaris and these coexisting species remain unclear, and we hypothesize that S. vulgaris can facilitate at least some species because within the patches vegetation is not grazed and soil water and nutrients may also be higher. We measured the maximum height, coverage and number of individuals of each vascular species, little cover and thickness of biological crust at the soil surface in 1 m 1 m plots in three types of microsites associated with 40 patches of S. vulgaris: (i) at the center, (ii) at the inner edge and (iii) outside the patches. We also took soil samples and measured soil water content and content of total N, P, K and organic matter. Soil water, nitrogen, organic matter and litter cover were the highest at the patch center, lowest outside the patches and intermediate at the inner edge of the patches, whereas thickness of biological crust was greater outside than at the center or at the inner edge. Among the 32 species recorded, six species preferred to occur within the patches, suggesting that S. vulgaris can facilitate these species most likely by grazing exclusion, increasing water and/or nitrogen resources in soil. However, most (19) species did not show preference and seven preferred outside. Also, species richness, pooled cover and number of individuals of all species were greater outside than within the patches, and such effects did not vary with the size of the S. vulgaris patches. These results suggest that the dominant interactions between S. vulgaris and the coexisting species are competition. The findings add to our knowledge that facilitation can be shown even when the competitive effects from the potential nurse plants are very strong

Floral scent of brazilian Passiflora: five species analised by dynamic headspace

ABSTRACT This study describes for the first time the chemical composition and olfactive description of floral scent from Brazilian Passiflora (Passiflora edulis Sim, Passiflora alata Curtis, Passiflora cincinnata Mast., Passiflora coccinea Aubl. and Passiflora quadrangularis L.). Five species were grown in greenhouse at the Agronomic Institute (IAC), São Paulo, Brazil. Volatile compounds were collected using dynamic headspace. Analyses of scent composition were performed by gas chromatograph coupled to mass spectrometer. Identification of chemical constituents was conducted through of retention index followed by comparative analysis of mass spectra with specialized databases. The olfactive descriptions of floral scent from each species was evaluated for a professional perfumer. High interspecific diversity was found between chemical compositions of floral scent within Passiflora and different bouquets were observed amount the studied species. Mayor constituents were linalool (P. alata), geraniol (P. quadrangularis), 1,4-dimethoxybenzene (P. edulis), benzaldehyde (P. cincinnata) and 2-methyl-3-pentanone (P. coccinea)