La prise d'informations visuelles chez la coccinelle Harmonia axyridis

Résumé Les capacités visuelles de la coccinelle H. axyridis, espèce utilisée en lutte biologique, ont été étudiées l'aide de formes géométriques différentes et de leurres qui miment un puceron. Les larves et les adultes de cette coccinelle semblent présenter une vision à distance (perception de formes géométriques) et une vision de proximité (perception de leurres comparables à des proies). Cette vision qui est plus développée chez les adultes, permet à cette coccinelle de changer l'orientation de ses déplacements soit pour entrer en contact avec ces cibles artificielles soit pour passer à proximité. Toutefois, ces performances ont été mises en évidence dans des conditions particulières, les cibles et les leurres présentant un fort contraste par rapport à l'environnement.     

Association between Obstructive Sleep Apnea and Community-Acquired Pneumonia

BackgroundWe hypothesized that obstructive sleep apnea (OSA) can predispose individuals to lower airway infections and community-acquired pneumonia (CAP) due to upper airway microaspiration. This study evaluated the association between OSA and CAP.MethodsWe performed a case-control study that included 82 patients with CAP and 41 patients with other infections (control group). The controls were matched according to age, sex and body mass index (BMI). A respiratory polygraph (RP) was performed upon admission for patients in both groups. The severity of pneumonia was assessed according to the Pneumonia Severity Index (PSI). The associations between CAP and the Epworth Sleepiness Scale (ESS), OSA, OSA severity and other sleep-related variables were evaluated using logistic regression models. The associations between OSA, OSA severity with CAP severity were evaluated with linear regression models and non-parametric tests.FindingsNo significant differences were found between CAP and control patients regarding anthropometric variables, toxic habits and risk factors for CAP. Patients with OSA, defined as individuals with an Apnea-Hypopnea Index (AHI) ≥10, showed an increased risk of CAP (OR = 2·86, 95%CI 1·29–6·44, p = 0·01). Patients with severe OSA (AHI≥30) also had a higher risk of CAP (OR = 3·18, 95%CI 1·11–11·56, p = 0·047). In addition, OSA severity, defined according to the AHI quartile, was also significantly associated with CAP (p = 0·007). Furthermore, OSA was significantly associated with CAP severity (p = 0·0002), and OSA severity was also associated with CAP severity (p = 0·0006).ConclusionsOSA and OSA severity are associated with CAP when compared to patients admitted to the hospital for non-respiratory infections. In addition, OSA and OSA severity are associated with CAP severity. These results support the potential role of OSA in the pathogenesis of CAP and could have clinical implications. This link between OSA and infection risk should be explored to investigate the relationships among gastroesophageal reflux, silent aspiration, laryngeal sensory dysfunction and CAP.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01071421","term_id":"NCT01071421"}}NCT01071421     

Adolescent idiopathic scoliosis and back pain

This broad narrative review addresses the relationship between adolescent idiopathic scoliosis (AIS) and back pain. AIS can be responsible for low back pain, particularly major cases. However, a linear relationship between back pain and the magnitude of the deformity cannot be expected for any individual patient. A large number of juvenile patients can remain pain-free. The long-term prognosis is rather benign for many cases and thus a tailored approach to the individual patient seems mandatory. The level of evidence available does not allow stringent recommendations for any of the disorders included in this review.     

Non-cyanobacterial diazotrophs mediate dinitrogen fixation in biological soil crusts during early crust formation

Biological soil crusts (BSCs) are key components of ecosystem productivity in arid lands and they cover a substantial fraction of the terrestrial surface. In particular, BSC N₂-fixation contributes significantly to the nitrogen (N) budget of arid land ecosystems. In mature crusts, N₂-fixation is largely attributed to heterocystous cyanobacteria; however, early successional crusts possess few N₂-fixing cyanobacteria and this suggests that microorganisms other than cyanobacteria mediate N₂-fixation during the critical early stages of BSC development. DNA stable isotope probing with ¹⁵N₂ revealed that Clostridiaceae and Proteobacteria are the most common microorganisms that assimilate ¹⁵N₂ in early successional crusts. The Clostridiaceae identified are divergent from previously characterized isolates, though N₂-fixation has previously been observed in this family. The Proteobacteria identified share >98.5% small subunit rRNA gene sequence identity with isolates from genera known to possess diazotrophs (for example, Pseudomonas, Klebsiella, Shigella and Ideonella). The low abundance of these heterotrophic diazotrophs in BSCs may explain why they have not been characterized previously. Diazotrophs have a critical role in BSC formation and characterization of these organisms represents a crucial step towards understanding how anthropogenic change will affect the formation and ecological function of BSCs in arid ecosystems.     

L'élevage en laboratoire,sur un hote de substitution dePhanerotoma flavitestacea [Hym.Braconidae] récolté dans le milieu naturel: conséquences sur le potentiel biotique de l'espèce

Résumé Des individus issus d'une population dePhanerotoma flavitestacea Fisher élevée dequis 1962 sur un h?te de substitutionAnagasta kühniella Zell., ont été réacclimatés avec succés, en 1968, à leur h?te naturelEctomyelois ceratoniae,Zell. dans la région de Nice où ce parasite n'existait pas jusqu'alors. Quatre ans après l'introduction, cette souche ?de plein air” ramenée au laboratoire et élevée dans les mêmes conditions que la souche d'origine, présente par rapport à celle-ci un certain nombre de particularités biologiques; le nombre d'ovocytes contenus dans les ovaires des jeunes femelles, le rythme de ponte et la ponte totale sont plus faibles, la maturité sexuelle est plus lente à s'établir. Par contre la durée de la période de ponte, la longévité et le nombre d'anomalies ovariennes ne sont pas modifiées.

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Summary Individuals from a population ofP. flavitestacea, reared from 1962 on the substitute hostAnagasta kuehniella, were successfully re-acclimatised in 1968 on their natural hostEctomylois ceratoniae, in the Nice region, were the parasite was hitherto unknown. Four years after the introduction, this “open air” strain, returned to the laboratory and raised under the same conditions as the original strain, showed certain biological pecularities: the number of ovocytes in the ovaries of the young females, the oviposition rhythm and the total oviposition were all reduced, and sexual maturity was delayed. On the other hand, duration of oviposition, longevity and number of ovarian aberrations were not affected.

     

Influence d'une alimentation préalable et du jeûne sur l'apparition de la recherche intensive des proies chez Semiadalia undecimnotata

Résumé Les prédateurs qui vivent aux dépens de ressources alimentaires groupées, modifient leur mode de déplacement après la capture et l'ingestion d'une proie. Ils passent de la recherche extensive (déplacements rapides et linéaires) à la recherche intensive (déplacements lents et sinueux). Chez les adultes et les larves de dernier stade de la coccinelle Semiadalia undecimnotata Schn. (Col., Coccinellidae), dans les premières heures qui suivent leur naissance ou leur mue, l'ingestion d'un premier puceron ne modifie pas les caractéristiques locomotrices individuelles: les déplacements restent de type extensif. Au début de chaque stade, cette coccinelle présente une période de sensibilisation à la proie rencontrée. Durant ces laps de temps, elle doit consommer plusieurs proies avant d'être capable d'adopter la recherche intensive. L'existence d'une période de jeûne avant cette première prise alimentaire favorise, au contraire, l'adoption de la recherche intensive.

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The ladybird, Semiadalia undecimnotata, like all other entomophagous insects feeding on relatively sedentary prey, exhibits two types of walking pattern during the search for prey: xtensive and intensive search. The latter is engaged following detection of visual or chemical cues. Changes in the ladybird search pattern: extensive search—a single prey capture—intensive search, were investigated in relation to experience of prior feeding-periods (experienced coccinellids) or to lack of such experience (naïve coccinellids) and with respect to changes in duration of fasting. The analysis of their pathways was performed initially by comparison of three locomotory paramètres: the number of stops (number/s), the walking speed (mm/s) and the turning-rate (degrees/s), and subsequently by statistical classification (principle components analysis). Unlike experienced coccinellids, observations of naïve coccinellids, indicate that a single feeding session during the three to five hours after emergence of an adult, or ecdysis of the larva, will change the walking pattern slightly. These animals will maintain extensive search or adopt a particular, intermediate locomotory pattern which is a development of extensive search but do not adopt intensive search. Fasting, for periods over twelve hours, favoured intensive search in populations studied. It is probable that the requirement to feed on more than one prey item before adopting intensive search involves concepts such as forms of learning (sensitization).

     

Chronic hyperammonemia alters in opposite ways membrane expression of GluA1 and GluA2 AMPA receptor subunits in cerebellum. Molecular mechanisms involved

Hyperammonemia contributes to altered neurotransmission and cognition in patients with hepatic encephalopathy. Hyperammonemia in rats affects differently high- and low-affinity AMPA receptors (AMPARs) in cerebellum. We hypothesized that hyperammonemia would alter differently membrane expression of AMPARs GluA1 and GluA2 subunits by altering its phosphorylation. This work aims were: 1) assess if hyperammonemia alters GluA1 and GluA2 subunits membrane expression in cerebellum and 2) analyze the underlying mechanisms.Hyperammonemia reduces membrane expression of GluA2 and enhances membrane expression of GluA1 in vivo. We show that changes in GluA2 and GluA1 membrane expression in hyperammonemia would be due to enhanced NMDA receptors activation which reduces cGMP levels and phosphodiesterase 2 (PDE2) activity, resulting in increased cAMP levels. This leads to increased protein kinase A (PKA) activity which activates phospholipase C (PLC) and protein kinase C (PKC) thus increasing phosphorylation of GluA2 in Ser880, which reduces GluA2 membrane expression, and phosphorylation of GluA1 in Ser831, which increases GluA1 membrane expression. Blocking NMDA receptors or inhibiting PKA, PLC or PKC normalizes GluA2 and GluA1 phosphorylation and membrane expression in hyperammonemic rats.Altered GluA2 and GluA1 membrane expression would alter signal transduction which may contribute to cognitive and motor alterations in hyperammonemia and hepatic encephalopathy.     

Performance of runners and swimmers after four weeks of intermittent hypobaric hypoxic exposure plus sea level training.

This double-blind, randomized, placebo-controlled trial examined the effects of 4 wk of resting exposure to intermittent hypobaric hypoxia (IHE, 3 h/day, 5 days/wk at 4,000-5,500 m) or normoxia combined with training at sea level on performance and maximal oxygen transport in athletes. Twenty-three trained swimmers and runners completed duplicate baseline time trials (100/400-m swims, or 3-km run) and measures for maximal oxygen uptake (VO(2max)), ventilation (VE(max)), and heart rate (HR(max)) and the oxygen uptake at the ventilatory threshold (VO(2) at VT) during incremental treadmill or swimming flume tests. Subjects were matched for sex, sport, performance, and training status and divided randomly between hypobaric hypoxia (Hypo, n = 11) and normobaric normoxia (Norm, n = 12) groups. All tests were repeated within the first (Post1) and third weeks (Post2) after the intervention. Time-trial performance did not improve in either group. We could not detect a significant difference between groups for a change in VO(2max), VE(max), HR(max), or VO(2) at VT after the intervention (group x test interaction P = 0.31, 0.24, 0.26, and 0.12, respectively). When runners and swimmers were considered separately, Hypo swimmers appeared to increase VO(2max) (+6.2%, interaction P = 0.07) at Post2 following a precompetition taper and increased VO(2) at VT (+8.9 and +12.1%, interaction P = 0.007 and 0.006, at Post1 and Post2). We conclude that this "dose" of IHE was not sufficient to improve performance or oxygen transport in this heterogeneous group of athletes. Whether there are potential benefits of this regimen for specific sports or training/tapering strategies may require further study.