Simple models including energy and spike constraints reproduce complex activity patterns and metabolic disruptions

In this work, we introduce new phenomenological neuronal models (eLIF and mAdExp) that account for energy supply and demand in the cell as well as the inactivation of spike generation how these interact with subthreshold and spiking dynamics. Including these constraints, the new models reproduce a broad range of biologically-relevant behaviors that are identified to be crucial in many neurological disorders, but were not captured by commonly used phenomenological models. Because of their low dimensionality eLIF and mAdExp open the possibility of future large-scale simulations for more realistic studies of brain circuits involved in neuronal disorders. The new models enable both more accurate modeling and the possibility to study energy-associated disorders over the whole time-course of disease progression instead of only comparing the initially healthy status with the final diseased state. These models, therefore, provide new theoretical and computational methods to assess the opportunities of early diagnostics and the potential of energy-centered approaches to improve therapies.     

Removal of sodium inactivation and block of sodium channels by chloramine-T in crayfish and squid giant axons.

Modification of sodium channels by chloramine-T was examined in voltage clamped internally perfused crayfish and squid giant axons using the double sucrose gap and axial wire technique, respectively. Freshly prepared chloramine-T solution exerted two major actions on sodium channels: (a) an irreversible removal of the fast Na inactivation, and (b) a reversible block of the Na current. Both effects were observed when chloramine-T was applied internally or externally (5-10 mM) to axons. The first effect was studied in crayfish axons. We found that the removal of the fast Na inactivation did not depend on the states of the channel since the channel could be modified by chloramine-T at holding potential (from -80 to -100 mV) or at depolarized potential of -30 mV. After removal of fast Na inactivation, the slow inactivation mechanism was still present, and more channels could undergo slow inactivation. This result indicates that in crayfish axons the transition through the fast inactivated state is not a prerequisite for the slow inactivation to occur. During chloramine-T treatment, a distinct blocking phase occurred, which recovered upon washing out the drug. This second effect of chloramine-T was studied in detail in squid axons. After 24 h, chloramine-T solution lost its ability to remove fast inactivation but retained its blocking action. After removal of the fast Na inactivation, both fresh and aged chloramine-T solutions blocked the Na currents with a similar potency and in a voltage-dependent manner, being more pronounced at lower depolarizing potentials.(ABSTRACT TRUNCATED AT 250 WORDS)     

Spontaneous hybridization between a male-sterile oilseed rape and two weeds

Spontaneous interspecific hybrids were produced under natural conditions (pollination by wind and bees) between a male-sterile cybrid Brassica napus (AACC, 2n = 38) and two weeds Brassica adpressa (AdAd, 2n = 14) and Raphanus raphanistrum (RrRr, 2n = 18). After characterization by chromosome counts and isozyme analyses, we observed 512 and 3 734 inter-specific seeds per m² for the B. napus-B. adpressa and B. napus-R. raphanistrum trials respectively. Most of the hybrids studied had the expected triploid structure (ACX). In order to quantify the frequency of allosyndesis between the genomes involved in the hybrids, their meiotic behavior was compared to a haploid of B. napus (AC). For the B. napus-B. adpressa hybrids, we concluded that probably no allosyndesis occurred between the two parental genomes, and that genetic factors regulating homoeologous chromosome pairing were carried by the B. adpressa genome. For the B. napus-R. raphanistrum hybrids, high chromosome pairing and the presence of multivalents (in 9.16% of the pollen mother cells) indicate that recombination is possible between chromosomes of different genomes. Pollen fertility of the hybrids ranged from 0 to 30%. Blackleg inoculation tests were performed on the three parental species and on the interspecific hybrids. BC₁ production with the weeds and with rapeseed was attempted. Results are discussed in regard to the risk assessment of transgenic rapeseed cultivation, F₁ hybrid rapeseed variety production, and rapeseed improvement.     

Polyphenols des feuilles de cotonniers et influence sur leur composition d'un choc hydrique ou nutritionnel

A range of phenolic compounds were found in leaves of three cotton species. Water and nutrient stress (sulfur deficiency) both caused a significant decrease in phenolic content. Possible interpretations of the observed phenomena are given.     

The Sequential Aerosol Technique: A Major Component in an Integrated Strategy of Intervention against Riverine Tsetse in Ghana

Background

An integrated strategy of intervention against tsetse flies was implemented in the Upper West Region of Ghana (9.62°–11.00° N, 1.40°–2.76° W), covering an area of ≈18,000 km² within the framework of the Pan-African Tsetse and Trypanosomosis Eradication Campaign. Two species were targeted: Glossina tachinoides and Glossina palpalis gambiensis.

Methodology/Principal Findings

The objectives were to test the potentiality of the sequential aerosol technique (SAT) to eliminate riverine tsetse species in a challenging subsection (dense tree canopy and high tsetse densities) of the total sprayed area (6,745 km²) and the subsequent efficacy of an integrated strategy including ground spraying (≈100 km²), insecticide treated targets (20,000) and insecticide treated cattle (45,000) in sustaining the results of tsetse suppression in the whole intervention area. The aerial application of low-dosage deltamethrin aerosols (0.33–0.35 g a.i/ha) was conducted along the three main rivers using five custom designed fixed-wings Turbo thrush aircraft. The impact of SAT on tsetse densities was monitored using 30 biconical traps deployed from two weeks before until two weeks after the operations. Results of the SAT monitoring indicated an overall reduction rate of 98% (from a pre-intervention mean apparent density per trap per day (ADT) of 16.7 to 0.3 at the end of the fourth and last cycle). One year after the SAT operations, a second survey using 200 biconical traps set in 20 sites during 3 weeks was conducted throughout the intervention area to measure the impact of the integrated control strategy. Both target species were still detected, albeit at very low densities (ADT of 0.27 inside sprayed blocks and 0.10 outside sprayed blocks).

Conclusions/Significance

The SAT operations failed to achieve elimination in the monitored section, but the subsequent integrated strategy maintained high levels of suppression throughout the intervention area, which will contribute to improving animal health, increasing animal production and fostering food security.     

Detection and Characterisation of Mutations Responsible for Allele-Specific Protein Thermostabilities at the Mn-Superoxide Dismutase Gene in the Deep-Sea Hydrothermal Vent Polychaete Alvinella pompejana

Alvinella pompejana (Polychaeta, Alvinellidae) is one of the most thermotolerant marine eukaryotes known to date. It inhabits chimney walls of deep-sea hydrothermal vents along the East Pacific Rise (EPR) and is exposed to various challenging conditions (e.g. high temperature, hypoxia and the presence of sulphides, heavy metals and radiations), which increase the production of dangerous reactive oxygen species (ROS). Two different allelic forms of a manganese-superoxide dismutase involved in ROS detoxification, ApMnSOD1 and ApMnSOD2, and differing only by two substitutions (M110L and A138G) were identified in an A. pompejana cDNA library. RFLP screening of 60 individuals from different localities along the EPR showed that ApMnSOD2 was rare (2 %) and only found in the heterozygous state. Dynamic light scattering measurements and residual enzymatic activity experiments showed that the most frequent form (ApMnSOD1) was the most resistant to temperature. Their half-lives were similarly long at 65 °C (>110 min) but exhibited a twofold difference at 80 °C (20.8 vs 9.8 min). Those properties are likely to be explained by the occurrence of an additional sulphur-containing hydrogen bond involving the M110 residue and the effect of the A138 residue on the backbone entropy. Our results confirm the thermophily of A. pompejana and suggest that this locus is a good model to study how the extreme thermal heterogeneity of the vent conditions may help to maintain old rare variants in those populations.     

Ostéomyélite de l’apophyse odontoïde : intérêt de la TEP/TDM au 18F-FDG dans le bilan d’extension infectieux à distance

Odontoid process is an atypical and very rare localization of osteomyelitis. We reported the case of a 72-year-old hemodialysed man with methicillin-sensitive Staphylococcus aureus osteomyelitis of the odontoid process. Osteomyelitis was diagnosed at MRI and ¹⁸F-FDG PET/CT. While clinical examination and conventional radiographs were non contributive, ¹⁸F-FDG PET/CT also allowed the diagnosis of right foot osteomylitis and multiple vertebral septic localizations. ¹⁸F-FDG PET/CT done at month 3 demonstrated a regression of the odontoid and foot hypermetabolic activity. This case illustrates the atypical presentation of this septic localization and the usefulness of ¹⁸F-FDG PET/CT to perform whole body screening and detect septic metastasis.