Invasive Plant and Experimental Venue Affect Tadpole Performance

Introductions of non-native predators and competitors appear to contribute to worldwide amphibian declines; however, potential negative impacts of invasive plants on habitat quality and amphibian populations have not been examined. Loss of diversity and alterations in ecosystem function associated with plant invasions may disrupt food webs, potentially leading to further declines of already threatened amphibian populations. We used a combination of small bins, mesocosms, and field experiments to examine the impacts of Eurasian purple loosestrife (Lythrum salicaria) replacing native cattails (Typha latifolia) in North American freshwater wetlands on survival, developmental rate, and diet (freshwater algae) of American toad (Bufo americanus) tadpoles. Tadpoles developed slower in L. salicaria compared to tadpoles developing in T. latifolia. This effect was consistent across experimental venues, although mesocosms showed this effect only in the second year of our study. Survival and development rates were always more variable in purple loosestrife than in cattail. In bins, tadpoles showed significantly reduced survival when raised in purple loosestrife extract and addition of leaf litter exacerbated this negative effect. Tadpole survival rates in mesocosms and field cages were not significantly different between plant species, most likely an effect of high variability among replicates. We suspect a combination of direct toxicity of high tannin concentrations in L. salicaria leaves and their indirect negative impacts on aquatic food webs are responsible for these results. Tadpole gut analyses revealed differences in algal communities among venues and between L. salicaria and T. latifolia suggesting that alterations in tadpole food quality and quantity contribute to the observed reduced tadpole performance. The replacement of native wetland plant species by L. salicaria does not represent a simple exchange of ecological equivalents and the function of invaded habitats for native species has clearly changed. While we were investigating only a single amphibian species, our results suggest that the impact of L. salicaria on ecosystem processes and aquatic food webs may be more general and likely to negatively affect other wetland species. The threats non-indigenous plants represent for amphibian populations and food webs may be underestimated, and warrant further investigation.     

The process of adaptation of flour beetles to new environments

Five populations derived from a composite, genetically heterogeneous strain of the flour beetle, Tribolium castaneum, were selected on new diets (dog food, powdered rice, brewers' yeast, wheat flour and oats) for 13–16 generations. A control population was reared on the standard medium (flour + 5% brewers' yeast). Adaptedness was measured in terms of (1) fitness parameters (survival and developmental time), (2) amylase activity levels (amylase is an essential digestive enzyme in flour beetles) and (3) food preference behavior.There were significant temporal trends in fitness components in the selected populations. Survival was initially low but increased with time. Developmental time decreased in later generations of selection. The control population showed the smallest increase in survival and no decrease in developmental time. When tested at the end of the experiment, survival to adulthood of eggs from each selected population on its selective diet was higher than that of control eggs. On the standard medium, no differences in survival among populations were detected. These results suggest that the improvement in fitness may indicate adaptation to the new environments created by the different food media.Amylase activity also increased temporally in 4 selected populations but not in the control (nor on unenriched wheat flour). Tests at the end of the experiment, however, suggest that this increase was, in large part, environmentally induced. We found no evidence that an adaptive genetic change in amylase regulation took place.There were no temporal trends in food-preference behavior during the selection process.     

Life cycle assessment of emerging technologies: Evaluation techniques at different stages of market and technical maturity

Life cycle assessment (LCA) analysts are increasingly being asked to conduct life cycle‐based systems level analysis at the earliest stages of technology development. While early assessments provide the greatest opportunity to influence design and ultimately environmental performance, it is the stage with the least available data, greatest uncertainty, and a paucity of analytic tools for addressing these challenges. While the fundamental approach to conducting an LCA of emerging technologies is akin to that of LCA of existing technologies, emerging technologies pose additional challenges. In this paper, we present a broad set of market and technology characteristics that typically influence an LCA of emerging technologies and identify questions that researchers must address to account for the most important aspects of the systems they are studying. The paper presents: (a) guidance to identify the specific technology characteristics and dynamic market context that are most relevant and unique to a particular study, (b) an overview of the challenges faced by early stage assessments that are unique because of these conditions, (c) questions that researchers should ask themselves for such a study to be conducted, and (d) illustrative examples from the transportation sector to demonstrate the factors to consider when conducting LCAs of emerging technologies. The paper is intended to be used as an organizing platform to synthesize existing methods, procedures and insights and guide researchers, analysts and technology developer to better recognize key study design elements and to manage expectations of study outcomes.     

Design and synthesis of acidic dipeptide hydroxamate inhibitors of procollagen C-proteinase.

Procollagen C-proteinase (PCP) is essential for the cleavage of procollagen to collagen in the extracellular matrix of animals and is, therefore, of major relevance to studies of ectopic deposition of collagen during fibrosis. In this study, we describe the design and synthesis of acidic side chain hydroxamate dipeptide inhibitors of PCP having IC50 values in the range 0.1-10 microM that mimic the location of aspartic acid residues in the P1' and P2' positions (i.e. immediately C-terminal) of the PCP cleavage site in procollagen. Assays of PCP using purified human type I procollagen (a natural substrate of PCP) showed that the structure activity relationship of the inhibitors was improved with a glutamic acid mimic at the P1' position. The results also showed that the presence of an acidic side chain at the P2' position was not necessary for PCP inhibition. Marimastat and BB3103, which are highly effective inhibitors of matrix metalloproteinases and ADAMS proteinases, respectively, did not inhibit PCP.     

Malaria,Schistosomiasis and Soil Transmitted Helminth Burden and Their Correlation with Anemia in Children Attending Primary Schools in Kinshasa,Democratic Republic of Congo

Background

Anaemia reduces cognitive potential in school children, retards their growth and predisposes them to other diseases. As there is a paucity of data on the current burden of P. falciparum, S. mansoni and soil transmitted helminths (STH) infections and their correlation with schoolchildren’s anemia in the Democratic Republic of Congo (DRC), we collect these data.

Methods

This study reports baseline data collected from a randomized controlled trial investigating the impact of IPT with SP and SP-PQ on anemia and malaria morbidity in Congolese schoolchildren (Trial registration: {"type":"clinical-trial","attrs":{"text":"NCT01722539","term_id":"NCT01722539"}}NCT01722539; PACTR201211000449323). S. mansoni and STH infections were assessed using kato-katz technique. Malaria infection and hemoglobin concentration were assessed using Blood smear and Hemocontrol device, respectively.

Results

A total of 616 primary schoolchildren from 4 to 13 years old were enrolled in the study. The prevalence of Plasmodium spp. infection was 18.5% (95%CI:15.6–21.9). Amongst those infected, 24 (21%), 40 (35.1%), 40 (35.1%), 10 (8.8%), had light, moderate, heavy, very high malaria parasite density, respectively. Above 9 years of age (p = 0.02), male and history of fever (p = 0.04) were both associated with malaria infection. The overall prevalence of S. mansoni infection was 6.4% (95%CI:4.4–9.1). Girls were associated with S. mansoni infection (p = 0.04). T. trichiura was the most prevalent STH infection (26.3%), followed by A. lumbricoides (20.1%). Co-infection with malaria-S. mansoni and malaria-STH was, respectively, 1.5% (CI_95%:0.7–3.3) and 6.4% (CI_95% 4.4–9.1). The prevalence of anemia was found to be 41.6% (95%CI:37.7–45.6) and anemia was strongly related with Plasmodium ssp infection (aOR:4.1; CI95%:2.6–6.5;p<0.001) and S. mansoni infection (aOR:3.3;CI95%:1.4–7.8;p<0.01).

Conclusion

Malaria and S. mansoni infection were strongly associated with high prevalence of anemia in schoolchildren. Therefore, specific school-based interventions, such as intermittent preventive treatment or prophylaxis, LLITN distribution, anthelminthic mass treatment and micronutrient supplementation are needed to improve school children’s health.     

Morphological evidence of sperm maturation in the ampulla ductus deferentis of the bull

The present lectin histochemical comparison of cauda epididymal and ampullary bovine sperm was conducted to investigate whether ampullary secretions are involved in altering the plasma-membrane glycoconjugates of sperm. A marked redistribution of glycoconjugates between sperm from these two regions was indeed revealed on the basis of changes in binding patterns of the following fluoroscein-isothiocyanate (FITC)-labelled lectins: wheat-germ agglutinin (WGA), Maclura pomifera agglutinin (MPA), Griffonia simplicifolia I agglutinin (GS I) and Bauhinea purpurea agglutinin (BPA). This was evidenced in the first three cases by a relative reversal of staining intensity between the acrosomal and post-acrosomal regions, and by a pronounced increase in the staining of the midpiece. Changes in the distribution of BPA binding sites were limited to the latter phenomenon. The results are compared with previous findings, discussed in the context of the hypermotility characteristic of ampullary sperm and related to previously reported differences in the lectin-binding patterns of the luminal and glandular epithelia.