Can the intake of antiparasitic secondary metabolites explain the low prevalence of hemoparasites among wild Psittaciformes?

Background: Parasites can exert selection pressure on their hosts through effects on survival, on reproductive success, on sexually selected ornament, with important ecological and evolutionary consequences, such as changes in population viability. Consequently, hemoparasites have become the focus of recent avian studies. Infection varies significantly among taxa. Various factors might explain the differences in infection among taxa, including habitat, climate, host density, the presence of vectors, life history and immune defence. Feeding behaviour can also be relevant both through increased exposure to vectors and consumption of secondary metabolites with preventative or therapeutic effects that can reduce parasite load. However, the latter has been little investigated. Psittaciformes (parrots and cockatoos) are a good model to investigate these topics, as they are known to use biological control against ectoparasites and to feed on toxic food. We investigated the presence of avian malaria parasites (Plasmodium), intracellular haemosporidians (Haemoproteus, Leucocytozoon), unicellular flagellate protozoans (Trypanosoma) and microfilariae in 19 Psittaciformes species from a range of habitats in the Indo-Malayan, Australasian and Neotropical regions. We gathered additional data on hemoparasites in wild Psittaciformes from the literature. We considered factors that may control the presence of hemoparasites in the Psittaciformes, compiling information on diet, habitat, and climate. Furthermore, we investigated the role of diet in providing antiparasitic secondary metabolites that could be used as self-medication to reduce parasite load. Results: We found hemoparasites in only two of 19 species sampled. Among them, all species that consume at least one food item known for its secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, were free from hemoparasites. In contrast, the infected parrots do not consume food items with antimalarial or even general antiparasitic properties. We found that the two infected species in this study consumed omnivorous diets. When we combined our data with data from studies previously investigating blood parasites in wild parrots, the positive relationship between omnivorous diets and hemoparasite infestation was confirmed. Individuals from open habitats were less infected than those from forests. Conclusions: The consumption of food items known for their secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, as well as the higher proportion of infected species among omnivorous parrots, could explain the low prevalence of hemoparasites reported in many vertebrates

Intégration spatiale et temporelle des entrées granulaires dans le cortex cérébelleux

Using whole cell patch clamp recording in rat cerebellum acute slices, I found that high frequency information processed in mossy fibre (MF)-granule cell (GC) pathway is conseved at the GC-Purkinje cell (PC) synapse. Bursts of action potential could evoke strong, excitatory postsynaptic currents at the PC soma that can follow high frequency rates, with high initial release probability, paired-pulse facilitation up to 700 Hz, and sustained facilitation during tensof pulses. This fast and sustained release is possible during bursts through the recruitment of reluctant vesicles that boost vesicular release. In a second study, by using precise RuBi-Glutamate uncaging onto granule cells, and by recording either PC, molecular layer interneurons or Golgi cells, 1 found that in the anterior vermis of the mouse cerebellum, GC-PC connection follows a precise spatial organisation. Specifie sets of PC, that can be identified using histochemical markers, receive inputs from small GC hotspots.En utilisant des enregistrements en patch-clamp sur des tranches aigues de cervelet de rat, j'ai observé que les informations à haute fréquence traitées dans la voie fibre moussues (FM)-cellules granulaires (CG) sont conservées à la synapse CG-cellule de Purkinje (CP). Des trains de potentiels d'action évoquent des courants postsynaptiques excitateurs importants, même à haute fréquence, avec une haute probabilité de libération initiale, une forte facilitation jusqu'à 700Hz, et ceci de façon soutenue. Ce mécanisme est possible grâce au recrutement de vésicules initialement réfractaires. Une seconde étude utilisant du decageage de Rubi-Glutamate sur les CG a permis de révéler une organisation spatialeprécise des connexions CG-PC, CG-Interneurones de la couche moléculaire (ICM) et CG-Cellules de Golgi (CGo). Des groupes spécifiques de CP/CGo ou ICM, identifiables via des marqueurs histochimiques sont contacté par des populations spécifiques de CG

Stereotyped spatial patterns of functional synaptic connectivity in the cerebellar cortex

International audienc

Response to Prone Position in COVID-19 and Non-COVID-19 Patients with Severe ARDS Supported by vvECMO

Background: For moderate to severe acute respiratory distress syndrome (ARDS), lung-protective ventilation combined with prolonged and repeated prone position (PP) is recommended. For the most severe patients for whom this strategy failed, venovenous extracorporeal membrane oxygenation (vv-ECMO) allows a reduction in ventilation-induced lung injury and improves survival. Some aggregated data have suggested a benefit regarding survival in pursuing PP during vv-ECMO. The combination of PP and vv-ECMO has been also documented in COVID-19 studies, although there is scarce evidence concerning respiratory mechanics and gas exchange response. The main objective was to compare the physiological response of the first PP during vv-ECMO in two cohorts of patients (COVID-19-related ARDS and non-COVID-19 ARDS) regarding respiratory system compliance (CRS) and oxygenation changes. Methods: This was a single-center, retrospective, and ambispective cohort study in the ECMO center of Marseille, France. ECMO was indicated according to the EOLIA trial criteria. Results: A total of 85 patients were included, 60 in the non-COVID-19 ARDS group and 25 in the COVID-19-related ARDS group. Lung injuries of the COVID-19 cohort exhibited significantly higher severity with a lower CRS at baseline. Concerning the main objective, the first PP during vv-ECMO was not associated with a change in CRS or other variation in respiratory mechanic variables in both cohorts. By contrast, oxygenation was improved only in the non-COVID-19 ARDS group after a return to the supine position. Mean arterial pressure was higher during PP as compared with a return to the supine position in the COVID-19 group. Conclusion: We found distinct physiological responses to the first PP in vv-ECMO-supported ARDS patients according to the COVID-19 etiology. This could be due to higher severity at baseline or specificity of the disease. Further investigations are warranted

NMDA binds a NMDA receptor and increases mEPSC frequency.

<p>A. The NMDA effect on mEPSC frequency is blocked in the presence of external Mg²⁺. Histogram on the left represents the number of mEPSCs as a function of recording time (bin 10 s), NMDA is applied as indicated by the two short horizontal bars, in the absence or presence of external Mg²⁺ (as indicated by the two horizontal long bars). Right: cumulative plot of the inter-event intervals when NMDA is applied in the absence (red curve) or presence (black curve) of Mg²⁺. B and C. The facilitatory effet of NMDA on mEPSC frequency is blocked by two NMDA receptor antagonists, MK801 and AP5 respectively. Left, histograms represent the number of mEPSCs as a function of recording time (bin 10 s). NMDA and NMDA receptor antagonists are applied as indicated by the horizontal bars. Right, cumulative plots of inter-event intervals in the presence of NMDA alone (red curves), or in the presence of receptor antagonists (black curves). Note that in the presence of Mg²⁺, MK801 and AP5, the distributions of inter-event intervals are shifted towards longer intervals.</p

Repetitive applications of NMDA promote the facilitatory effect on mEPSC frequency.

<p>A. Current traces showing mEPSCs before (left) and after (right) a second application of NMDA. B (same cell as in A). Histogram representing the number of mEPSCs as a function of recording time (bin 10 s). During the short horizontal bars NMDA is applied at 10⁻⁵ M (bars 1 and 2) and at 5×10⁻⁶ M. (bar 3). C. Cumulative plots of inter-event intervals in control conditions (black curve) in the presence of NMDA after the first application (1, red curves) and second application (2, blue curve).</p

NMDA increases the frequency of mEPSCs in Purkinje cells recorded in a young (P18) slice culture.

<p>Upper record: currents traces obtained at −40 mV in the presence of TTX and Gabazine before (left) and after NMDA application (right). Transient inward currents represent mEPSCs. Lower graphs: (same cell as in A) cumulative probability plots of inter-event intervals (left) under control conditions (black trace) and in the presence of NMDA (red trace); amplitude histogram distribution under control conditions (middle) and in the presence of NMDA (right). In both cases the amplitude distribution was fitted using a gaussian function with a peak value indicated on each graph. Note that in the presence of NMDA the distribution of inter-event intervals is shifted towards shorter intervals whereas the amplitude distribution is almost unchanged.</p