Prevalence of intestinal parasite among patients attending two hospitals in French Guiana: A 6-year retrospective study

IntroductionIntestinal parasitic diseases are a global health problem. Due to its equatorial climate, vast territory with isolated areas and the precariousness of its population, intestinal parasitosis is considered to be a major issue in French Guiana but only few data are available and these mainly focus on specific population. We aimed at determining the parasitic index and at describing the characteristics of these infections in order to develop preventive strategies.Material and methodsWe retrospectively analysed all the parasitological samples recorded in the register of the two main laboratories of French Guiana between 2011 and 2016. The parasitic index was the percentage of parasitised patients in comparison with the total number of subjects studied. A patient who underwent several positive parasitological examinations was considered only once in the analysis at the time of the first sampling.ResultsA total of 15,220 parasitological samples of 9,555 patients were analysed and 2,916 were positive in 1,521 patients. The average infestation rate and parasitic index were 19.2% and 16.0%, respectively. The parasitic index remained stable between 2011 (18.2%) and 2016 (18.3%). The patients were mainly men (66.4%), with a median age of 33.0 years (26.3% of patients were under 18 years of age) and lived mainly in the Central Agglomeration (48.2%) and in West Guiana (37.4%). Hookworms were the most common parasite (25.2%) followed by Entamoeba coli (13.3%), Strongyloides stercoralis (10.9%) and Giardia intestinalis (10.8%). Among the infected patients, 31.0% presented mixed infections and 67.5% of them had at least one pathogenic parasite. The patients aged from 0 to 18 years presented significantly more polyparasitism (30.9%) than monoparasitism (24.3%, p<0.001). Ancylostoma sp and Strongyloides stercoralis were mainly diagnosed during the rainy season (59.5% and 64.7% respectively), in men (78.6% and 81.1% respectively) and in patients aged from 18 to 65 years (86.6% and 76.6% respectively) whereas, Giardia intestinalis infected mostly children under 5 years (59.5%) of age.ConclusionAlthough it may not be representative of the entire Guyanese population, the parasitic index remained high and stable from 2011 and 2016 and it justifies the need for an active prevention program as it was already done in the other French overseas departments such as Martinique and Guadeloupe.     

Perturbation of nuclear–cytosolic shuttling of Rx1 compromises extreme resistance and translational arrest of potato virus X transcripts

Many plant intracellular immune receptors mount a hypersensitive response (HR) upon pathogen perception. The concomitant localized cell death is proposed to trap pathogens, such as viruses, inside infected cells, thereby preventing their spread. Notably, extreme resistance (ER) conferred by the potato immune receptor Rx1 to potato virus X (PVX) does not involve the death of infected cells. It is unknown what defines ER and how it differs from HR-based resistance. Interestingly, Rx1 can trigger an HR, but only upon artificial (over)expression of PVX or its avirulence coat protein (CP). Rx1 has a nucleocytoplasmic distribution and both pools are required for HR upon transient expression of a PVX-GFP amplicon. It is unknown whether mislocalized Rx1 variants can induce ER upon natural PVX infection. Here, we generated transgenic Nicotiana benthamiana producing nuclear- or cytosol-restricted Rx1 variants. We found that these variants can still mount an HR. However, nuclear- or cytosol-restricted Rx1 variants can no longer trigger ER or restricts viral infection. Interestingly, unlike the mislocalized Rx1 variants, wild-type Rx1 was found to compromise CP protein accumulation. We show that the lack of CP accumulation does not result from its degradation but is likely to be linked with translational arrest of its mRNA. Together, our findings suggest that translational arrest of viral genes is a major component of ER and, unlike the HR, is required for resistance to PVX.     

The smell of cooperation: rats increase helpful behaviour when receiving odour cues of a conspecific performing a cooperative task

Reciprocity can explain cooperative behaviour among non-kin, where individuals help others depending on their experience in previous interactions. Norway rats (Rattus norvegicus) cooperate reciprocally according to direct and generalized reciprocity. In a sequence of four consecutive experiments, we show that odour cues from a cooperating conspecific are sufficient to induce the altruistic help of rats in a food-exchange task. When rats were enabled to help a non-cooperative partner while receiving olfactory information from a rat helping a conspecific in a different room, they helped their non-cooperative partner as if it was a cooperative one. We further show that the cues inducing altruistic behaviour are released during the act of cooperation and do not depend on the identity of the cue provider. Remarkably, olfactory cues seem to be more important for cooperation decisions than experiencing a cooperative act per se. This suggests that rats may signal their cooperation propensity to social partners, which increases their chances to receive help in return.     

Life in a fragment: Evolution of foraging strategies of translocated collared brown lemurs,Eulemur collaris,over an 18-year period

While the drivers of primate persistence in forest fragments have been often considered at the population level, the strategies to persist in these habitats have been little investigated at the individual or group level. Considering the rapid variation of fragment characteristics over time, longitudinal data on primates living in fragmented habitats are necessary to understand the key elements for their persistence. Since translocated animals have to cope with unfamiliar areas and face unknown fluctuations in food abundance, they offer the opportunity to study the factors contributing to successful migration between fragments. Here, we illustrated the evolution of the foraging strategies of translocated collared brown lemurs (Eulemur collaris) over an 18-year period in the Mandena Conservation Zone, south-east Madagascar. Our aim was to explore the ability of these frugivorous lemurs to adjust to recently colonized fragmented forests. Although the lemurs remained mainly frugivorous throughout the study period, over the years we identified a reduction in the consumption of leaves and exotic/pioneer plant species. These adjustments were expected in frugivorous primates living in a degraded area, but we hypothesize that they may also reflect the initial need to cope with an unfamiliar environment after the translocation. Since fragmentation is often associated with the loss of large trees and native vegetation, we suggest that the availability of exotic and/or pioneer plant species can provide an easy-to-access, nonseasonal food resource and be a key factor for persistence during the initial stage of the recolonization.     

A reinvestigation of the pre-steady-state ATPase activity of the nitrogenase from Azotobacter vinelandii.

The pre-steady-state ATPase activity of nitrogenase has been reinvestigated. The exceptionally high burst in the hydrolysis of MgATP by the nitrogenase from Azotobacter vinelandii communicated by Cordewener et al. (1987) [Cordewener J., ten Asbroek A., Wassink H., Eady R. R., Haaker H. & Veeger C. (1987) Eur. J. Biochem. 162, 265-270] was found to be caused by an apparatus artefact. A second possible artefact in the determination of the stoichiometry of the pre-steady-state ATPase activity of nitrogenase was observed. Acid-quenched mixtures of dithionite-reduced MoFe or Fe protein of Azotobacter vinelandii nitrogenase and MgATP contained phosphate above the background level. It is proposed that due to this reaction, quenched reaction mixtures of nitrogenase and MgATP may contain phosphate in addition to the phosphate released by the ATPase activity of the nitrogenase complex. It was feasible to monitor MgATP-dependent pre-steady-state proton production by the absorbance change at 572 nm of the pH indicator o-cresolsulfonaphthalein in a weakly buffered solution. At 5.6 degrees C, a pre-steady-state phase of H+ production was observed, with a first-order rate constant of 2.2 s-1, whereas electron transfer occurred with a first-order rate constant of 4.9 s-1. At 20.0 degrees C, MgATP-dependent H+ production and electron transfer in the pre-steady-state phase were characterized by observed rate constants of 9.4 s-1 and 104 s-1, respectively. The stopped-flow technique failed to detect a burst in the release of protons by the dye-oxidized nitrogenase complex. It is concluded that the hydrolysis rate of MgATP, as judged by proton release, is lower than the rate of electron transfer from the Fe protein to the MoFe protein.     

Differential methylation at the 5′ and the 3′ CCGG sites flanking the X chromosomal hypervariable DXS255 locus

Summary The degree of methylation at the 5 and 3 CCGG sequences flanking the variable number of tandem repeat (VNTR) region of the DXS255 locus at Xp11.22 was analysed separately in several haematopoietic cell lineages. The 5 CCGG site on active chromosomes was found to be completely methylated in B and T lymphocytes and granulocytes. Methylation of the 5 site on inactive X chromosomes differed between females (0%–60%), but was consistent in different cell lineages obtained from individual females. In contrast, methylation at the 3 CCGG site on active chromosomes was found to vary in B lymphocytes (40%–100%), whereas complete methylation was found in T lymphocytes and granulocytes. The extent of methylation on inactive X chromosomes was found to differ significantly between B lymphocytes (17%), T lymphocytes (54%) and granulocytes (82%). Thus, methylation at the 5 CCGG site seems to be primarily related to the status of X chromosome inactivation, whereas methylation at the 3 CCGG site is mainly subject to cell-lineage-specific influences.     

Magainins affect respiratory control, membrane potential and motility of hamster spermatozoa

The hypothesis was tested that the magainin peptides, known to compromise bacterial and mitochondrial energetics, are highly active against spermatozoa. A mixture of magainin A and PGLa (1:1) caused a 50% reduction in motility of hamster spermatozoa at 4 micrograms/ml total peptide concentration. All motility was lost at 8 micrograms/ml. At this concentration, respiratory control was released and respiration in the presence of uncoupler was inhibited. Uptake of the lipophilic cation tetraphenyl phosphonium was largely abolished by addition of magainin A and PGLa showed synergism with respect to release of respiratory control.     

Inhibition of the phosphate-stimulated cytochromec oxidase activity by thiophosphate

Yeast and mammalian cytochromec oxidase activity is inhibited by thiophosphate. This inhibition was observed when using either whole mitochondria or the isolated or reconstituted enzyme. The kinetics of the reduction reaction enabled us to demonstrate that thiophosphate acted on th electrons transfer between hemesa anda ₃. With whole mitochondria, phosphate alone stimulated respiration. The inhibition induced by thiophosphate was suppressed by phosphate only in mitochondria, but not when the isolated enzyme was used. The possibility of a kinetic regulation is discussed.Abbreviations CCCP p-carbonylcyanidem-chlorophenylhydrazone - TMPD N,N,N,N-tetramethylp-phenylenediamine - SPi thiophosphate