CHEMOTHERAPY,WITHIN‐HOST ECOLOGY AND THE FITNESS OF DRUG‐RESISTANT MALARIA PARASITES

A major determinant of the rate at which drug‐resistant malaria parasites spread through a population is the ecology of resistant and sensitive parasites sharing the same host. Drug treatment can significantly alter this ecology by removing the drug‐sensitive parasites, leading to competitive release of resistant parasites. Here, we test the hypothesis that the spread of resistance can be slowed by reducing drug treatment and hence restricting competitive release. Using the rodent malaria model Plasmodium chabaudi, we found that low‐dose chemotherapy did reduce competitive release. A higher drug dose regimen exerted stronger positive selection on resistant parasites for no detectable clinical gain. We estimated instantaneous selection coefficients throughout the course of replicate infections to analyze the temporal pattern of the strength and direction of within‐host selection. The strength of selection on resistance varied through the course of infections, even in untreated infections, but increased immediately following drug treatment, particularly in the high‐dose groups. Resistance remained under positive selection for much longer than expected from the half life of the drug. Although there are many differences between mice and people, our data do raise the question whether the aggressive treatment regimens aimed at complete parasite clearance are the best resistance‐management strategies for humans.     

Integrated view and comparative analysis of baseline protein expression in mouse and rat tissues

The increasingly large amount of proteomics data in the public domain enables, among other applications, the combined analyses of datasets to create comparative protein expression maps covering different organisms and different biological conditions. Here we have reanalysed public proteomics datasets from mouse and rat tissues (14 and 9 datasets, respectively), to assess baseline protein abundance. Overall, the aggregated dataset contained 23 individual datasets, including a total of 211 samples coming from 34 different tissues across 14 organs, comprising 9 mouse and 3 rat strains, respectively.In all cases, we studied the distribution of canonical proteins between the different organs. The number of canonical proteins per dataset ranged from 273 (tendon) and 9,715 (liver) in mouse, and from 101 (tendon) and 6,130 (kidney) in rat. Then, we studied how protein abundances compared across different datasets and organs for both species. As a key point we carried out a comparative analysis of protein expression between mouse, rat and human tissues. We observed a high level of correlation of protein expression among orthologs between all three species in brain, kidney, heart and liver samples, whereas the correlation of protein expression was generally slightly lower between organs within the same species. Protein expression results have been integrated into the resource Expression Atlas for widespread dissemination.     

Being Attractive Brings Advantages: The Case of Parrot Species in Captivity

Background

Parrots are one of the most frequently kept and bred bird orders in captivity. This increases poaching and thus the potential importance of captive populations for rescue programmes managed by zoos and related institutions. Both captive breeding and poaching are selective and may be influenced by the attractiveness of particular species to humans. In this paper, we tested the hypothesis that the size of zoo populations is not only determined by conservation needs, but also by the perceived beauty of individual parrot species assessed by human observers.

Methodology/Principal Findings

For the purpose of data collection, we defined four sets of species (40 parrots, 367 parrots, 34 amazons, 17 macaws). Then, we asked 776 human respondents to evaluate parrot pictures of the selected species according to perceived beauty and we analyzed its association with color and morphological characters. Irrespective of the species set, we found a good agreement among the respondents. The preferred species tended to be large, colorful, and long-tailed.

Conclusions/Significance

We repeatedly confirmed significant, positive association between the perceived beauty and the size of worldwide zoo population. Moreover, the range size and body size appeared to be significant predictors of zoo population size. In contrast, the effects of other explanatory variables, including the IUCN (International Union for Conservation of Nature) listing, appeared insignificant. Our results may suggest that zoos preferentially keep beautiful parrots and pay less attention to conservation needs.     

Application expérimentale de mycelium d'Erynia neoaphidis [Zygomycètes: Entomophthorales] dans des populations de pucerons sur laitues en serre maraîchère: étude du suivi de l'inoculum par caractérisation enzymatique

Résumé Au cours d'une expérimentation réalisée en serre à Rennes, en 1983, on a éprouvé l'efficacité contre les pucerons de la laitueAulacorthum solani (Kaltenbach) etMacrosiphum euphorbiae (Thomas) d'une biopréparation d'Entomophthorale constituée de mycélium d'une souche deErynia neoaphidis Remaudière & Hennebert. L'étude de l'implantation de cette souche a été entreprise grace à une technique de caractérisation enzymatique. Les populations de pucerons implantées expérimentalement en début d'essai sont faiblement attaquées par des mycoses (5 % de mortalité). La caractérisation enzymatique des souches d'Entomophthorales isolées de pucerons trouvés morts au cours de l'expérimentation montre que la souche deE. neoaphidis introduite s'est implantée dans les populations aphidiennes, mais qu'elle est par la suite remplacée par un inoculum autochtone de la même espèce. On observe également le développement dès le début de l'expérimentation d'un inoculum deC. obscurus qui ne correspond pas à la souche introduite 2 ans auparavant lors d'une précédente expérimentation.      

A Brave New World for an Old World Pest: Helicoverpa armigera (Lepidoptera: Noctuidae) in Brazil

The highly polyphagous Old World cotton bollworm Helicoverpa armigera is a quarantine agricultural pest for the American continents. Historically H. armigera is thought to have colonised the American continents around 1.5 to 2 million years ago, leading to the current H. zea populations on the American continents. The relatively recent species divergence history is evident in mating compatibility between H. zea and H. armigera under laboratory conditions. Despite periodic interceptions of H. armigera into North America, this pest species is not believed to have successfully established significant populations on either continent. In this study, we provide molecular evidence via mitochondrial DNA (mtDNA) cytochrome oxidase I (COI) and cytochrome b (Cyt b) partial gene sequences for the successful recent incursion of H. armigera into the New World, with individuals being detected at two sites (Primavera do Leste, Pedra Preta) within the State of Mato Grosso in Brazil. The mtDNA COI and Cyt b haplotypes detected in the Brazilian H. armigera individuals are common throughout the Old World, thus precluding identification of the founder populations. Combining the two partial mtDNA gene sequences showed that at least two matrilines are present in Brazil, while the inclusion of three nuclear DNA Exon-Primed Intron-Crossing (EPIC) markers identified a further two possible matrilines in our samples. The economic, biosecurity, resistance management, ecological and evolutionary implications of this incursion are discussed in relation to the current agricultural practices in the Americas.     

The N'-terminal domain of glyceraldehyde-3-phosphate dehydrogenase of the apicomplexan Plasmodium falciparum mediates GTPase Rab2-dependent recruitment to membranes

Spatial and temporal distribution of the glycolytic enzymes glyceraldehyde-3-phosphate dehydrogenase (pfGAPDH) and aldolase (pfAldolase) of Plasmodium falciparum were investigated using specific mAbs and indirect immunofluorescence analysis (IFA). Both glycolytic enzymes were co-localized during ring and trophozoite stages of both liver and asexual blood stage parasites. During schizogony, pfGAPDH became associated with the periphery of the parasites and eventually accumulated in the apical region of merozoites, while pfAldolase showed no segregation. Subcellular fractionation experiments demonstrated that pfGAPDH was found in both the membrane-containing pellet and the supernatant fraction of parasite lysates. In contrast, pfAldolase was only found in the supernatant fraction. A quantitative binding assay showed that pfGAPDH could be recruited to HeLa cell microsomal membranes in response to mammalian GTPase Rab2, indicating that Rab2-dependent recruitment of cytosolic components to membranes is conserved in evolution. Two overlapping fragments of pfGAPDH (residues 1-192 and 133-337) were evaluated in the microsomal binding assay. We found that the N'-terminal fragment competitively inhibited Rab2-stimulated pfGAPDH recruitment. Thus, the domain mediating the evolutionarily conserved Rab2-dependent membrane recruitment is located in the N'-terminus of GAPDH. Together, these results suggest that pfGAPDH exerts non-glycolytic function(s) in P. falciparum, possibly including a role in vesicular transport and biogenesis of apical organelles.