Manganese toxicity in Drosophila melanogaster: extension of the life span by resveratrol

The effect of resveratrol was studied on the life span and motor activity of Drosophila melanogaster treated with manganese (Mn). Two days after emerging from the pupa, male wild type D. melanogaster were fed for 13 days with corn media containing 15?mM Mn. Thereafter, Drosophila were divided into six groups of 300 flies each: (1) the flies remained treated with Mn; (2) began treatment with 0.43?mM resveratrol (Mn-resveratrol group); (3) received no additional treatment (Mn-no treatment group); (4) simultaneously fed with Mn and resveratrol (Mn?+?resveratrol group). In addition, a control (5) with no treatment and another group (6) fed only with resveratrol after emerging from the pupa were included. All Mn-treated flies (group 1) were dead on the 25th day. The life span in the resveratrol group was 91?±?0.33 days (mean?±?S.E.M.) and in Mn-resveratrol flies was 83?±?2 days. These two values were significantly higher than those detected in the control (5) and Mn-no treatment (group 3) flies whose life span were 68?±?0.33 and 67?±?2.31 days, respectively. The Mn?+?resveratrol-fed flies had a markedly higher life span (31?±?1.53 days) than Mn-fed flies (23?±?0.88 days). In the flies that received Mn (Mn and Mn?+?resveratrol groups), the motor activity decreased significantly with respect to control (groups 5) and the Mn–resveratrol and resveratrol groups. In conclusion, resveratrol increased significantly the life span of Mn-treated D. melanogaster.     

Tracking the evolution of waste recycling research using overlay maps of science

Tracking the evolution of research in waste recycling science (WRS) can be valuable for environmental agencies, as well as for recycling businesses. Maps of science are visual, easily readable representations of the cognitive structure of a branch of science, a particular area of research or the global spectrum of scientific production. They are generally built upon evidence collected from reliable sources of information, such as patent and scientific publication databases. This study uses the methodology developed by Rafols et al. (2010) to make a "double overlay map" of WRS upon a basemap reflecting the cognitive structure of all journal-published science, for the years 2005 and 2010. The analysis has taken into account the cognitive areas where WRS articles are published and the areas from where it takes its intellectual nourishing, paying special attention to the growing trends of the key areas. Interpretation of results lead to the conclusion that extraction of energy from waste will probably be an important research topic in the future, along with developments in general chemistry and chemical engineering oriented to the recovery of valuable materials from waste. Agricultural and material sciences, together with the combined economics, politics and geography field, are areas with which WRS shows a relevant and ever increasing cognitive relationship.     

A qualitative analysis of the stability of the root-microorganism soil system II. Combined effect of several factors

This is the second part of a study aimed at achieving some qualitative understanding of the stability properties of the root-microorganism soil system. The first part concentrated on the effect on this stability of different patterns of either nitrogen- or energy-limiting conditions. To this end, a mathematical model has been developed. The model, the theory and some results of the first part are extended here to more complex situations.A factor is first defined to measure the likelihood of the danger of extinction of the roots. It is found that this danger is increased with increasing specific mortality rates, decreasing nitrogen input and/or increasing periods of time during which decomposers are nitrogen-limited. It is also found that the danger of extinction is not directly proportional to absolute nitrogen losses from the system. Some possible explanations in terms of compensatory mechanisms of the roots are discussed.     

Pollinator diversity increases fruit production in Mexican coffee plantations: The importance of rustic management systems

Pollination is an ecological process that provides important services to humans. Pollination service in agroecosystems depends on several factors, including the land management systems used by farmers. Here we focused on the effects of insect pollinator diversity on coffee fruit production along a gradient of management systems in central Veracruz, Mexico. The gradient ranged from low environmental impact management systems (the native forest is not completely removed) to high environmental impact management systems (the native forest is completely removed). We hypothesized that pollinator diversity should be higher in low-impact systems. Then, if fruit production is positively related to pollinator diversity, plantations with low-impact management systems should display higher fruit production than plantations with high-impact management systems. We used observational and experimental data to test this hypothesis. Our results indicated that low-impact management systems have higher species richness and relative diversity (measured with the Shannon-Wiener diversity index) of pollinators than high-impact management systems. In all cases, fruit production was positively related with species richness and diversity of pollinators. Moreover, fruit production was higher in low-impact than in high-impact management systems. These results suggest that the diversity of insect pollinators can be influenced by the management system applied by farmers, and that such effects may have strong consequences on coffee fruit production.     

Reverse positional orientation in a neotropical orb-web spider, <Emphasis Type="Italic">Verrucosa arenata</Emphasis>

Most orb-web spiders face downwards in the web. A downward orientation has been proposed to be the optimal strategy because spiders run faster downwards and thus can catch prey quicker. Consequently, orb-web spiders also extend their web in the lower part, leading to top-down web asymmetry. Since the majority of orb-web spiders face downwards, it has been difficult to test the effect of orientation on prey capture and web asymmetry. In this study, we explored the influence of reverse orientation on foraging efficiency and web asymmetry in Verrucosa arenata, a neotropical orb-web spider that faces upwards in the web. We show that reverse orientation does not imply reverse web asymmetry in this species. V. arenata spiders captured more prey in the lower part of the web but more prey per area on the upper part. The average running speeds of spiders did not differ between upward and downward running, but heavier spiders took longer to capture prey while running upwards. We discuss these findings in the context of foraging efficiency and web asymmetry.