Field estimates of fitness costs of the pace‐of‐life in an endangered damselfly

Theory predicts that within‐population differences in the pace‐of‐life can lead to cohort splitting and produce marked intraspecific variation in body size. Although many studies showed that body size is positively correlated with fitness, many argue that selection for the larger body is counterbalanced by opposing physiological and ecological selective mechanisms that favour smaller body. When a population split into cohorts with different paces of life (slow or fast cohort), one would expect to detect the fitness–size relationship among and within cohorts, that is, (a) slower‐developing cohort has larger body size and higher fitness than faster‐developing cohort, and (b) larger individuals within each cohort show higher fitness than smaller individuals. Here, we test these hypotheses in capture–mark–recapture field surveys that assess body size, lifespan, survival and lifetime mating success in two consecutive generations of a partially bivoltine aquatic insect, Coenagrion mercuriale, where the spring cohort is slower‐developing than the autumn cohort. As expected, body size was larger in the slow‐developing cohort, which is consistent with the temperature‐size rule and also with the duration of development. Body size seasonal variation was greater in slow‐developing cohort most likely because of the higher variation in age at maturity. Concordant with theory, survival probability, lifespan and lifetime mating success were higher in the slow‐developing cohort. Moreover, individual body size was positively correlated with survival and mating success in both cohorts. Our study confirms the fitness costs of fast pace‐of‐life and the benefits of larger body size to adult fitness.     

When mental fatigue maybe characterized by Event Related Potential (P300) during virtual wheelchair navigation

The goal of this study is to investigate the influence of mental fatigue on the event related potential P300 features (maximum pick, minimum amplitude, latency and period) during virtual wheelchair navigation. For this purpose, an experimental environment was set up based on customizable environmental parameters (luminosity, number of obstacles and obstacles velocities). A correlation study between P300 and fatigue ratings was conducted. Finally, the best correlated features supplied three classification algorithms which are MLP (Multi Layer Perceptron), Linear Discriminate Analysis and Support Vector Machine. The results showed that the maximum feature over visual and temporal regions as well as period feature over frontal, fronto-central and visual regions were correlated with mental fatigue levels. In the other hand, minimum amplitude and latency features didn’t show any correlation. Among classification techniques, MLP showed the best performance although the differences between classification techniques are minimal. Those findings can help us in order to design suitable mental fatigue based wheelchair control.     

NF-kappaB-mediated modulation of inducible nitric oxide synthase activity controls induction of the Epstein-Barr virus productive cycle by transforming growth factor beta 1

Transforming growth factor beta 1 (TGF-β1) signal transduction has been implicated in many second-messenger pathways, including the NF-κB pathway. We provide evidence of a novel TGF-β1-mediated pathway that leads to extracellular signal-regulated kinase (ERK) 1/2 phosphorylation, which in turn induces expression of an Epstein-Barr virus (EBV) protein, ZEBRA, that is responsible for the induction of the viral lytic cycle. This pathway includes two unexpected steps, both of which are required to control ERK 1/2 phosphorylation: first, a quick and transient activation of NF-κB, and second, downregulation of inducible nitric oxide synthase (iNOS) activity that requires the participation of NF-κB activity. Although necessary, NF-κB alone is not sufficient to produce downregulation of iNOS, suggesting that another uncharacterized event(s) is involved in this pathway. Dissection of the steps involved in the switch from the EBV latent cycle to the lytic cycle will be important to understand how virus-host relationships modulate the innate immune system.     

Fast liquid chromatography-mass spectrometry glutathione measurement in whole blood: micromolar GSSG is a sample preparation artifact

We describe a new, fast (6 min) and reliable method to measure reduced or oxidized glutathione (GSH) or (GSSG) in whole blood. The method is based on a LC/MS measurement in positive electrospray ionization mode after a chromatographic separation on a specific column which does not need any counter-ion in the mobile phase, improving the sensitivity of detection. A 50 microl sample of whole blood is sufficient for analysis. We demonstrate that the lack of an alkylating agent during the sample preparation brings out an underestimation of GSH and an artefactual production of GSSG, corresponding to 2-3% of GSH. The simultaneous use of N-ethyl-maleimide and a strong deproteinising acid prevents these two drawbacks. This efficient and new method of preparation and analysis lets us show that, unexpectedly, GSH is stable in whole blood for some hours and that deproteinised samples can be stored without GSH loss for at least three weeks at -20 or -80 degrees C. The reference interval, measured on 22 volunteers, on blood samples collected either with heparin or with EDTA, is 1310 +/- 118 microM for GSH and 0.62 microM for GSSG. The within-run precision of this method, with gamma glutamyl-glutamic acid as an internal standard, evaluated in three successive series (n = 30), lies between 2.1 and 4.8% for a GSH level at 580 or 1150 microM. The one step sample preparation we propose seems well suited for GSH routine measurements in hospital laboratories and avoids any underestimation of GSH, a now well accepted biomarker of oxidative stress.     

Kinetic measurement by LC/MS of gamma-glutamylcysteine ligase activity

gamma-Glutamylcysteine ligase (GCL) combines cysteine and glutamate through its gamma carboxyl moiety as the first step for glutathione (GSH) synthesis and is considered to be the rate-limiting enzyme in this pathway. The enzyme is a heterodimer, with a heavy catalytic and a light regulatory subunit, which plays a critical role in the anti-oxidant response. Besides the original method of Seelig designed for the measurement of a purified enzyme, few endpoint methods, often unrefined, are available for measuring it in complex biological samples. We describe a new, fast and reliable kinetic LC/MS method which enabled us to optimize its detection. l-2-Aminobutyrate is used instead of cysteine (to avoid glutathione synthetase interference) as triggering substrate with saturating concentrations of glutamate and ATP; the gamma glutamylaminobutyrate formed is measured at m/z=233 at regular time intervals. Reaction rate is maximum because ATP is held constant by enzymatic recycling of ADP by pyruvate kinase and phosphoenolpyruvate. The repeatability of the method is good, with CV% of 6.5 and 4% for catalytic activities at, respectively 0.9 and 34 U/l. The affinities of rat and human enzymes for glutamate and aminobutyrate are in good agreement with previous published data. However, unlike the rat enzyme, human GCL is not sensitive to reduced glutathione and displays a more basic optimum pH.     

On the restoration of the last relict population of a dragonfly <Emphasis Type="Italic">Urothemis edwardsii</Emphasis> Selys (Libellulidae: Odonata) in the Mediterranean

The restoration of endangered relict populations is challenging in conservation biology because they require specific environmental conditions within an inhospitable regional climate. Urothemis edwardsii Selys is the most endangered dragonfly in the Mediterranean with only one known relict small population (Lac Bleu) left in Northeast Algeria. With the absence of successful (re-)colonization over the last two decades, the restoration of the species became a top priority. To improve the status of the species in Northeast Algeria, we carried out a reintroduction and translocation scheme during 2011–2015 and assessed the changes in distribution and population size. Our restoration plan led to the emergence of three populations of which one was restored (Lac Noir), one resulted from successful translocation (Lac Tonga Northeast), and one established after successful colonization (Lac Tonga Southwest). In three localities (Lac Noir, Lac Tonga Northeast, and Lac Tonga Southwest), signs of population growth were observed, whereas no significant trend in the source population (Lac Bleu) was detected. A new population (El Graeate) was also recorded in 2015, but its origin is uncertain. Capture-mark-recapture on adults conducted in 2015 in two sites (Lac Bleu and Lac Noir) showed low recapture rates and no sign of dispersal between the two sites. Dispersal capacity of the species and conservation implications of adult distribution are discussed. This study highlights the importance of using biological indicators in selecting host habitats for the restoration of critically threatened populations.     

Research on Parvovirus B19 infections and chronic articular manifestations in a Tunisian hospital

Parvovirus B19 infection is often associated with acute and chronic joint diseases thus suggesting an etiologic role for the virus in these pathologies. In this work, we looked for a possible correlation between Parvovirus B19 infection and certain types of chronic inflammatory rheumatisms. We therefore, screened a population of 100 patients with different chronic inflammatory rheumatismal affections for serological markers of Parvovirus B19 infection. All patients were Tunisians of both sexes, who presented at the service of Rheumatology of the Charles Nicolle Hospital, Tunis. One hundred blood donors were taken as controls. Specific Immunoenzyme Assays of the ELISA type (Biotrin International, France) were used to detect anti-Parvovirus IgG and IgM. On the other hand, viral DNA was sought by nested PCR in synovial fluid from 14 patients. The data obtained indicate that specific anti-Parvovirus B19 IgG was detectable in the sera of 80.7% of patients and 43% of controls. In contrast, none of the sera was found positive for specific IgM antibodies. Synovial fluid samples could be collected from 14 anti-Parvovirus B19 seropositive patients and were tested for the presence of viral DNA. None of the samples was found positive. The results of our serological study reinforce the hypothesis that Parvovirus B19 infection is associated with rheumatismal joint affections. However, the lack of detectable viral DNA in synovial fluid of the tested seropositive patients points to an indirect role of the virus in these joint disorders.