Persistence of Cortical Sensory Processing during Absence Seizures in Human and an Animal Model: Evidence from EEG and Intracellular Recordings

Absence seizures are caused by brief periods of abnormal synchronized oscillations in the thalamocortical loops, resulting in widespread spike-and-wave discharges (SWDs) in the electroencephalogram (EEG). SWDs are concomitant with a complete or partial impairment of consciousness, notably expressed by an interruption of ongoing behaviour together with a lack of conscious perception of external stimuli. It is largely considered that the paroxysmal synchronizations during the epileptic episode transiently render the thalamocortical system incapable of transmitting primary sensory information to the cortex. Here, we examined in young patients and in the Genetic Absence Epilepsy Rats from Strasbourg (GAERS), a well-established genetic model of absence epilepsy, how sensory inputs are processed in the related cortical areas during SWDs. In epileptic patients, visual event-related potentials (ERPs) were still present in the occipital EEG when the stimuli were delivered during seizures, with a significant increase in amplitude compared to interictal periods and a decrease in latency compared to that measured from non-epileptic subjects. Using simultaneous in vivo EEG and intracellular recordings from the primary somatosensory cortex of GAERS and non-epileptic rats, we found that ERPs and firing responses of related pyramidal neurons to whisker deflection were not significantly modified during SWDs. However, the intracellular subthreshold synaptic responses in somatosensory cortical neurons during seizures had larger amplitude compared to quiescent situations. These convergent findings from human patients and a rodent genetic model show the persistence of cortical responses to sensory stimulations during SWDs, indicating that the brain can still process external stimuli during absence seizures. They also demonstrate that the disruption of conscious perception during absences is not due to an obliteration of information transfer in the thalamocortical system. The possible mechanisms rendering the cortical operation ineffective for conscious perception are discussed, but their definite elucidation will require further investigations.     

Dimensions of Temperament Modulate Cue-Controlled Behavior: A Study on Pavlovian to Instrumental Transfer in Horses (Equus Caballus)

Pavlovian to instrumental transfer (PIT) is a central factor in how cues influence animal behavior. PIT refers to the capacity of a Pavlovian cue that predicts a reward to elicit or increase a response intended to obtain the same reward. In the present study, using an equine model, we assessed whether PIT occurs in hoofed domestic animals and whether its efficacy can be modulated by temperamental dimensions. To study PIT, horses were submitted to Pavlovian conditioning whereby an auditory–visual stimulus was repeatedly followed by food delivery. Then, horses were submitted to instrumental conditioning during which they learned to touch with their noses an object signaled by the experimenter in order to obtain the same reward. During the PIT test, the Pavlovian conditioned stimulus was presented to the animal in the absence of reward. At the end of the experiment, a battery of behavioral tests was performed on all animals to assess five temperamental dimensions and investigate their relationships with instrumental performance. The results indicate that PIT can be observed in horses and that its efficacy is greatly modulated by individual temperament. Indeed, individuals with a specific pattern of temperamental dimensions (i.e., higher levels of gregariousness, fearfulness, and sensory sensitivity) exhibited the strongest PIT. The demonstration of the existence of PIT in domesticated animals (i.e., horses) is important for the optimization of its use by humans and the improvement of training methods. Moreover, because PIT may be implicated in psychological phenomena, including addictive behaviors, the observation of relationships between specific temperamental dimensions and PIT efficacy may aid in identifying predisposing temperamental attributes.     

Agro-Environmental Determinants of Avian Influenza Circulation: A Multisite Study in Thailand,Vietnam and Madagascar

Outbreaks of highly pathogenic avian influenza have occurred and have been studied in a variety of ecological systems. However, differences in the spatial resolution, geographical extent, units of analysis and risk factors examined in these studies prevent their quantitative comparison. This study aimed to develop a high-resolution, comparative study of a common set of agro-environmental determinants of avian influenza viruses (AIV) in domestic poultry in four different environments: (1) lower-Northern Thailand, where H5N1 circulated in 2004–2005, (2) the Red River Delta in Vietnam, where H5N1 is circulating widely, (3) the Vietnam highlands, where sporadic H5N1 outbreaks have occurred, and (4) the Lake Alaotra region in Madagascar, which features remarkable similarities with Asian agro-ecosystems and where low pathogenic avian influenza viruses have been found. We analyzed H5N1 outbreak data in Thailand in parallel with serological data collected on the H5 subtype in Vietnam and on low pathogenic AIV in Madagascar. Several agro-environmental covariates were examined: poultry densities, landscape dominated by rice cultivation, proximity to a water body or major road, and human population density. Relationships between covariates and AIV circulation were explored using spatial generalized linear models. We found that AIV prevalence was negatively associated with distance to the closest water body in the Red River Delta, Vietnam highlands and Madagascar. We also found a positive association between AIV and duck density in the Vietnam highlands and Thailand, and with rice landscapes in Thailand and Madagascar. Our findings confirm the important role of wetlands-rice-ducks ecosystems in the epidemiology of AI in diverse settings. Variables influencing circulation of the H5 subtype in Southeast Asia played a similar role for low pathogenic AIV in Madagascar, indicating that this area may be at risk if a highly virulent strain is introduced.     

Distinct roles of TLR2 and the adaptor ASC in IL-1beta/IL-18 secretion in response to Listeria monocytogenes

Apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC) is an adaptor molecule that has recently been implicated in the activation of caspase-1. We have studied the role of ASC in the host defense against the intracellular pathogen Listeria monocytogenes. ASC was found to be essential for the secretion of IL-1beta/IL-18, but dispensable for IL-6, TNF-alpha, and IFN-beta production, in macrophages infected with Listeria. Activation of caspase-1 was abolished in ASC-deficient macrophages, whereas activation of NF-kappaB and p38 was unaffected. In contrast, secretion of IL-1beta, IL-6, and TNF-alpha was reduced in TLR2-deficient macrophages infected with Listeria; this was associated with impaired activation of NF-kappaB and p38, but normal caspase-1 processing. Analysis of Listeria mutants revealed that cytosolic invasion was required for ASC-dependent IL-1beta secretion, consistent with a critical role for cytosolic signaling in the activation of caspase-1. Secretion of IL-1beta in response to lipopeptide, a TLR2 agonist, was greatly reduced in ASC-null macrophages and was abolished in TLR2-deficient macrophages. These results demonstrate that TLR2 and ASC regulate the secretion of IL-1beta via distinct mechanisms in response to Listeria. ASC, but not TLR2, is required for caspase-1 activation independent of NF-kappaB in Listeria-infected macrophages.     

AtPRD1 is required for meiotic double strand break formation in Arabidopsis thaliana

The initiation of meiotic recombination by the formation of DNA double-strand breaks (DSBs) catalysed by the Spo11 protein is strongly evolutionary conserved. In Saccharomyces cerevisiae, Spo11 requires nine other proteins for meiotic DSB formation, but, unlike Spo11, few of these proteins seem to be conserved across kingdoms. In order to investigate this recombination step in higher eukaryotes, we have isolated a new gene, AtPRD1, whose mutation affects meiosis in Arabidopsis thaliana. In Atprd1 mutants, meiotic recombination rates fall dramatically, early recombination markers (e.g., DMC1 foci) are absent, but meiosis progresses until achiasmatic univalents are formed. Besides, Atprd1 mutants suppress DSB repair defects of a large range of meiotic mutants, showing that AtPRD1 is involved in meiotic recombination and is required for meiotic DSB formation. Furthermore, we showed that AtPRD1 and AtSPO11-1 interact in a yeast two-hybrid assay, suggesting that AtPRD1 could be a partner of AtSPO11-1. Moreover, our study reveals similarity between AtPRD1 and the mammalian protein Mei1, suggesting that AtPRD1 could be a Mei1 functional homologue.     

Phenotypic characterization of pore mutants of the Vibrio cholerae porin OmpU

General-diffusion porins form large β-barrel channels that control the permeability of the outer membrane of gram-negative bacteria to nutrients, some antibiotics, and external signals. Here, we have analyzed the effects of mutations in the OmpU porin of Vibrio cholerae at conserved residues that are known to affect pore properties in the Escherichia coli porins OmpF and OmpC. Various phenotypes were investigated, including sensitivity to β-lactam antibiotics, growth on large sugars, and sensitivity to and biofilm induction by sodium deoxycholate, a major bile component that acts as an external signal for multiple cellular responses of this intestinal pathogen. Overall, our results indicate that specific residues play different roles in controlling the passage of various compounds. Mutations of barrel wall arginine residues that protrude in the pore affect pore size and growth in the presence of large sugars or sodium deoxycholate. Sensitivity to large cephalosporins is mostly affected by D116, located on the L3 loop, whose homolog in E. coli, OmpF, is a known binding determinant for these drugs. L3 loop residues also affect biofilm induction. The results are interpreted in terms of a homology model based on the structures of E. coli porins.     

Immigrational Background Affects the Effectiveness of a School‐based Overweight Prevention Program Promoting Water Consumption

We tested whether a simple overweight prevention program promoting water consumption in elementary schools is equally effective in children with an immigrational background (MIG) and in those without (non‐MIG). Thus, a secondary analysis of a controlled cluster trial, lasting one school year, was conducted. Thirty‐two elementary schools located in low socioeconomic districts in two German cities were included. Of the 2,950 school children analyzed, 1,306 were MIG children. Water fountains were installed in the schools of the intervention group (IG) and teachers held lessons to promote water consumption. Control schools (control group (CG)) did not receive any intervention. Before and after intervention, body weight and height was measured. Overweight was defined by age‐ and sex‐specific BMI cutoffs that are linked to an adult BMI of 25 kg/m². Beverage consumption was assessed in questionnaires. Modification of intervention effects by immigrational background was tested by interaction terms. The immigrational background modified the intervention effect on prevalence and remission of overweight (interaction term: P = 0.03 and P = 0.02), but not on the incidence of overweight (P = 0.06). After intervention, the risk of being overweight was reduced in the IG compared to the CG among non‐MIG (odds ratio = 0.51, 95% confidence interval (CI): 0.31–0.83), but not among MIG children (odds ratio = 1.02, 95% CI: 0.63–1.65). After intervention, water consumption significantly increased in the IG equally among both, non‐MIG and MIG, by ～1 glass/day. A simple school‐based intervention promoting water consumption prevented overweight in non‐MIG children, but failed in MIG children. Different beverage consumption, among other lifestyle factors, may account for this effect but scientific discussion remains open.     

When leaves act like flowers: how dwarf palms attract their pollinators

In pollination mutualisms, floral odours are signals advertising the presence and location of rewards. However, in the case of the dwarf palm (Chamaerops humilis) and its species‐specific pollinating weevil (Derelomus chamaeropsis), rewards and advertisements are spatially separated. Flowers provide their specific pollinators with food and sites for both egg laying and larval development, but do not advertise them with floral odours or visually conspicuous petals. Insect behavioural bioassays revealed that pollinators are attracted by scents emitted by the leaves, which provide no rewards. These scents are released by large structures located at the sinuses of the palmate leaf. Such scent‐releasing structures have not been previously reported on palm leaves, and we suggest that they may represent an ‘exaptation’ (pre‐existing trait that acquired new functions). We also propose that such functional crossovers between vegetative and reproductive domains may be more frequent in plants than is currently documented.