To lek or not to lek: mating strategies of male fallow deer

We studied the mating system of fallow deer (Dama dama) for6 years in central Italy. Males in this population could defendterritories that were either single, clumped in leks, or satelliteto leks. The most highly successful males in our study werein leks. When we considered all males, there were no significantdifferences in average copulatory success according to territorytype because many lek males did not achieve any copulations,which were seen in only a few lek territories. The variancein copulatory success, however, was much greater for leks thanelsewhere. Single territories were occupied for shorter timesduring the rut than lek territories. Fighting among males wasmore frequent in the lek, even when we excluded highly successfullek males from the analysis. Chases of nonterritorial malesand harem size were correlated with the number of copulationsachieved by individual males, but did not vary according toterritory type. Copulatory success of some individuals increasedwith age, but there were no age differences among males holdingdifferent types of territories. Satellite males switched tolek territoriality in the course of one rut, but switches fromsingle territory to lek territory were rare. We suggest thatmales in single territories are inferior competitors that selecta low-risk, lowbenefit strategy, whereas those in lek territorieswhere no copulations were seen may be attempting to establishthemselves on the lek to increase their copulatory success infuture years.     

Comparative aspects of opioid-dopamine interaction

1. Opiate receptors are found in invertebrate as well as mammalian systems, often in proximity to dopamergic systems. This review summarizes the interrelationships between these two transmitter systems in invertebrates. 2. The comparative data discussed here are of considerable significance. They recall that the opioid-dopamine relationships first demonstrated in the mammalian nervous system also apply to invertebrates and are therefore of more general importance. The results obtained in the mollusk Mytilus strengthen the concept that the activity of dopaminergic neurons may be modulated by afferent opioid signals and that, even in "more primitive" animals, interneuronal transfer of information is more complex than formerly visualized. Furthermore, the data indicate that endogenous opioids may exert tonic control over dopamine metabolism, thus implying interdependence of the two systems.     

Synthesis,semipreparative HPLC separation,biological evaluation,and 3D-QSAR of hydrazothiazole derivatives as human monoamine oxidase B inhibitors

The present study reports on synthesis in high yields (70–99%), HPLC enantioseparation, inhibitory activity against human monoamino oxidases, and molecular modeling including 3D-QSAR studies, of a large series of (4-aryl-thiazol-2-yl)hydrazones (1–45). Most of the synthesized compounds proved to be potent and selective inhibitors of hMAO-B isoform in the micromolar or nanomolar range, thus demonstrating that hydrazothiazole could be considered a good pharmacophore to design new hMAO-B inhibitors. Due to the presence in some derivatives of a chiral center, we also performed a semipreparative chromatographic enantioseparation of these compounds obtained by a stereoconservative pattern. The separated enantiomers were submitted to in vitro biological evaluation to point out the stereorecognition of the active site of the enzyme towards these structures. Finally, a 3D-QSAR study was carried out using Comparative Molecular Field Analysis (CoMFA), aiming to deduce rational guidelines for the further structural modification of these lead compounds.     

Antagonism against Rhizoctonia solani and fungitoxic metabolite production by some Penicillium isolates

A number of Penicillium isolates were recovered in association to Rhizoctonia solani strains pathogenic on tobacco and from soil on plates pre-colonized by the pathogen itself. Their antagonism toward R. solaniAG-2-1 was evaluated in dual cultures in vitro. Inhibition of growth was evident to some extent in most pairings, while hyphal interactions referable to mycoparasitic relationships were not observed. However, the occurrence of plasmolysis and/or vacuolisation and the induction of monilioid cells were indicative of the release of bioactive compounds. Therefore, production of fungitoxic metabolites was tested by adding concentrated culture filtrates of each Penicillium isolate to the growth medium of R. solani. Complete and lasting inhibition was incited by culture filtrates of some isolates belonging to P. brevicompactum, P. expansum, and P. pinophilum. Three purified compounds, respectively mycophenolic acid, patulin and 3-O-methylfunicone, which were extracted from culture filtrates, were able to inhibit R. solani in vitro. Their production was also detected in dual cultures of the same Penicilliumstrains with R. solani prepared in sterilized soil and when the Penicilliumstrains were cultured directly on R. solani mycelium harvested from liquid cultures. The possible role of such metabolites in antagonism of the above-mentioned Penicilliumspecies against R. solani is discussed.     

A global assessment of forest surface albedo and its relationships with climate and atmospheric nitrogen deposition

We present a global assessment of the relationships between the short‐wave surface albedo of forests, derived from the MODIS satellite instrument product at 0.5° spatial resolution, with simulated atmospheric nitrogen deposition rates (N_dep), and climatic variables (mean annual temperature T_m and total annual precipitation P), compiled at the same spatial resolution. The analysis was performed on the following five forest plant functional types (PFTs): evergreen needle‐leaf forests (ENF); evergreen broad‐leaf forests (EBF); deciduous needle‐leaf forests (DNF); deciduous broad‐leaf forests (DBF); and mixed‐forests (MF). Generalized additive models (GAMs) were applied in the exploratory analysis to assess the functional nature of short‐wave surface albedo relations to environmental variables. The analysis showed evident correlations of albedo with environmental predictors when data were pooled across PFTs: T_m and N_dep displayed a positive relationship with forest albedo, while a negative relationship was detected with P. These correlations are primarily due to surface albedo differences between conifer and broad‐leaf species, and different species geographical distributions. However, the analysis performed within individual PFTs, strengthened by attempts to select ‘pure’ pixels in terms of species composition, showed significant correlations with annual precipitation and nitrogen deposition, pointing toward the potential effect of environmental variables on forest surface albedo at the ecosystem level. Overall, our global assessment emphasizes the importance of elucidating the ecological mechanisms that link environmental conditions and forest canopy properties for an improved parameterization of surface albedo in climate models.     

The determinants of stability in the human prion protein: insights into folding and misfolding from the analysis of the change in the stabilization energy distribution in different conditions

The dynamic evolution of the PrP(C) from its NMR-derived conformation to a beta-sheet-rich, aggregation-prone conformation is studied through all-atom, explicit solvent molecular dynamics in different temperature and pH conditions. The trajectories are analyzed by means of a recently introduced energy decomposition approach aimed at identifying the key residues for the stabilization and folding of the protein. It is shown that under native conditions the stabilization energy is concentrated in regions of the helices H1 and H3, whereas under misfolding conditions (low pH, high temperature, or mutations in selected sites) it is spread out over helix H2. Misfolding appears to be a rearrangement of the chain that disrupts most of the native secondary structure of the protein, producing some beta-rich conformations with an energy distribution similar to that of the native state.     

Reconciling empirical interactions and species coexistence

Coexistence in ecological communities is governed largely by the nature and intensity of species interactions. Countless studies have proposed methods to infer these interactions from empirical data, yet models parameterised using such data often fail to recover observed coexistence patterns. Here, we propose a method to reconcile empirical parameterisations of community dynamics with species‐abundance data, ensuring that the predicted equilibrium is consistent with the observed abundance distribution. To illustrate the approach, we explore two case studies: an experimental freshwater algal community and a long‐term time series of displacement in an intertidal community. We demonstrate how our method helps recover observed coexistence patterns, capture the core dynamics of the system, and, in the latter case, predict the impacts of experimental extinctions. Collectively, these results demonstrate an intuitive approach for reconciling observed and empirical data, improving our ability to explore the links between species interactions and coexistence in natural systems.     

Reactive oxygen and nitrogen species are involved in sorbitol-induced apoptosis of human erithroleukaemia cells K562

In this study, we found that production of both reactive oxygen (ROS) and nitrogen (RNS) species is a very early event related to treatment with hyperosmotic concentration of sorbitol. The production of nitric oxide (NO) was paralleled by the increase of the mRNA and protein level of the inducible form of the nitric oxide synthase (iNOS). ROS and RNS enhancement, process concomitant to the failure of mitochondrial trans-membrane potential (ΔΨ), was necessary for the induction of apoptosis as demonstrated by the protection against sorbitol-mediated toxicity observed after treatment with ROS scavengers or NOS inhibitors. The synergistic action of ROS and RNS was finally demonstrated by pre-treatment with rosmarinic acid that, by powerfully buffering both these species, prevents impairment of ΔΨ and cell death. Overall results suggest that the occurrence of apoptosis upon sorbitol treatment is an event mediated by oxidative/nitrosative stress rather than a canonical hyperosmotic shock.