National University of Comahue

About: National University of Comahue is a education organization based out in Neuquén, Argentina. It is known for research contribution in the topics: Population & Species richness. The organization has 2242 authors who have published 4498 publications receiving 87157 citations. The organization is also known as: UNCOMA & UNCo.

Latitude Dictates Plant Diversity Effects on Instream Decomposition

Abstract: Running waters contribute substantially to global carbon fluxes through decomposition of terrestrial plant litter by aquatic microorganisms and detritivores. Diversity of this litter may influence instream decomposition globally in ways that are not yet understood. We investigated latitudinal differences in decomposition of litter mixtures of low and high functional diversity in 40 streams on 6 continents and spanning 113° of latitude. Despite important variability in our dataset, we found latitudinal differences in the effect of litter functional diversity on decomposition, which we explained as evolutionary adaptations of litter-consuming detritivores to resource availability. Specifically, a balanced diet effect appears to operate at lower latitudes versus a resource concentration effect at higher latitudes. The latitudinal pattern indicates that loss of plant functional diversity will have different consequences on carbon fluxes across the globe, with greater repercussions likely at low latitudes.

Physical and functional properties of spray-dried powders from blackcurrant juice and extracts obtained from the waste of juice processing

Abstract: Blackcurrants contain high levels of polyphenolics, particularly flavonols and anthocyanins, which contribute to their high antioxidant activity. The aims of this work were the recovery of bioactive compounds from the remaining solid (waste) after processing blackcurrant juice and to obtain spray-dried powders from the blackcurrant juice and extracts. The extraction of bioactive compounds from the fruit pulp was performed by ultrasound-assisted extraction. Experiments were conducted to select the more suitable solvent, and citric acid was chosen. Then, to optimize the extraction conditions (time, solvent concentration, and amplitude) an experimental design using a Box-Behnken Design was done. Comparing the optimized extract with the fruit, 31% total monomeric anthocyanins, 19% total phenolic compounds, and 10% antioxidant capacity were obtained. The optimized extract and the juice were mixed and spray dried, using maltodextrin as carrier matrix. A blackcurrant powder with low hygroscopicity 14.46 ± 0.13 (g a.w./100 g d.m) and high solubility 94.25 ± 4% was obtained. High concentration of bioactive compounds and antioxidant capacity was recorded: Total monomeric anthocyanins 63.01 ± 1 (mg cyn-3-glu/100 g.d.m), total phenolic content 116.87 ± 5 (mg gallic acid/100 g d.m.), and antioxidant capacity 144.40 ± 0.11 (mg eq Trolox/100 g.d.m.).

Mycosporine-glutaminol-glucoside, a UV-absorbing compound of two Rhodotorula yeast species

Abstract: High-performance liquid chromatography (HPLC), alone or in combination with mass spectrometry (MS), was used to screen the basidiomycetous yeasts Rhodotorula minuta and R. slooffiae isolated from lakes for the presence of UV-absorbing compounds. Mycosporine-glutaminol-glucoside (maximum absorption, 310 nm), a UV-photoprotective mycosporine known in terrestrial fungi, was the major UVabsorbing compound found in these species. This is the first identification of a mycosporine in yeasts. The presence of this compound seems to be a promising chemotaxonomical marker for yeast systematics. Copyright  2004 John Wiley & Sons, Ltd.

Reciprocal interactions between a facilitator, natives, and exotics in tropical alpine plant communities

Abstract: Facilitation by nurse plants has received considerable attention, but the feedback effects of beneficiaries on the benefactor fitness remain comparatively unexplored In particular, to our knowledge there have been no studies of feedback effects of exotic species on nurse plants Furthermore, there have been few studies of how exotic plants interact with native beneficiaries, potentially generating indirect effects on the nurse Here, through spatial association analyses, we estimate the reciprocal interactions between the cushion nurse-plant Arenaria musciformis, native beneficiaries, and the dominant exotic Rumex acetosella (a fast growing heliophile species) in a tropical alpine ecosystem of the Venezuelan Andes, locally known as paramos We recorded the density of natives and the exotic within Arenaria cushions and in paired open areas at three sites and calculated Relative Interaction Indices (RII) to explore the effects of the cushion Then, we analyzed the feedback effects of Rumex and the natives on the density of flowers produced by Arenaria Finally, we analyzed how Rumex abundance is related to the abundance of native species inside and outside cushions RIIs indicated a facilitative effect of cushions on the abundance of native plants, but no effect on Rumex We found a negative relationship between the density of natives and cushion flower density, but no such relationship for Rumex However, at high densities, Rumex was negatively correlated with the abundance of the natives both inside and outside of cushions Our results suggest the possibility of complex reciprocal interactions between nurses, natives and exotics, and that native and exotic plants can differ in their feedback effects on nurse cushions Native plants appeared to be facilitated by cushions and then develop a parasitic relationship with their nurses In contrast, the exotic Rumex had a neutral interaction with the nurse, but competitive effects on the native beneficiary community, which could indirectly modulate the feedback effects of natives on the nurse These results highlight the importance of analyzing direct and indirect reciprocal interactions and the impacts of exotic invaders for understanding alpine community assembly