A pan-European epidemiological study reveals honey bee colony survival depends on beekeeper education and disease control

Reports of honey bee population decline has spurred many national efforts to understand the extent of the problem and to identify causative or associated factors. However, our collective understanding of the factors has been hampered by a lack of joined up trans-national effort. Moreover, the impacts of beekeeper knowledge and beekeeping management practices have often been overlooked, despite honey bees being a managed pollinator. Here, we established a standardised active monitoring network for 5 798 apiaries over two consecutive years to quantify honey bee colony mortality across 17 European countries. Our data demonstrate that overwinter losses ranged between 2% and 32%, and that high summer losses were likely to follow high winter losses. Multivariate Poisson regression models revealed that hobbyist beekeepers with small apiaries and little experience in beekeeping had double the winter mortality rate when compared to professional beekeepers. Furthermore, honey bees kept by professional beekeepers never showed signs of disease, unlike apiaries from hobbyist beekeepers that had symptoms of bacterial infection and heavy Varroa infestation. Our data highlight beekeeper background and apicultural practices as major drivers of honey bee colony losses. The benefits of conducting trans-national monitoring schemes and improving beekeeper training are discussed

Catalase characterization and implication in bleaching of a symbiotic sea anemone

Symbiotic cnidarians are marine invertebrates harboring photosynthesizing microalgae (named zooxanthellae), which produce great amounts of oxygen and free radicals upon illumination. Studying antioxidative balance is then crucial to understanding how symbiotic cnidarians cope with ROS production. In particular, it is suspected that oxidative stress triggers cnidarian bleaching, i.e., the expulsion of zooxanthellae from the animal host, responsible for symbiotic cnidarian mass mortality worldwide. This study therefore investigates catalase antioxidant enzymes and their role in bleaching of the temperate symbiotic sea anemone Anemonia viridis. Using specific separation of animal tissues (ectoderm and endoderm) from the symbionts (zooxanthellae), spectrophotometric assays and native PAGE revealed both tissue-specific and activity pattern distribution of two catalase electrophoretypes, E1 and E2. E1, expressed in all three tissues, presents high sensitivity to the catalase inhibitor aminotriazole (ATZ) and elevated temperatures. The ectodermal E1 form is responsible for 67% of total catalase activity. The E2 form, expressed only within zooxanthellae and their host endodermal cells, displays low sensitivity to ATZ and relative thermostability. We further cloned an ectodermal catalase, which shares 68% identity with mammalian monofunctional catalases. Last, 6 days of exposure of whole sea anemones to ATZ (0.5 mM) led to effective catalase inhibition and initiated symbiont expulsion. This demonstrates the crucial role of this enzyme in cnidarian bleaching, a phenomenon responsible for worldwide climate-change-induced mass mortalities, with catastrophic consequences for marine biodiversity

Thermal threshold and sensitivity of the only symbiotic Mediterranean gorgonian Eunicella singularis by morphometric and genotypic analyses

International audienceThe only symbiotic Mediterranean gorgonian, Eunicella singularis, has faced several mortality events connected to abnormal high temperatures. Since thermotolerance data remain scarce, heat-induced necrosis was monitored in aquarium by morphometric analysis. Gorgonian tips were sampled at two sites: Medes (Spain) and Riou (France) Islands, and at two depths: 15 m and-35 m. Although coming from contrasting thermal regimes, seawater above 28 degrees C led to rapid and complete tissue necrosis for all four populations. However, at 27 degrees C, the time length leading to 50% tissue necrosis allowed us to classify samples within three classes of thermal sensitivity. Irrespectively of the depth, Medes specimens were either very sensitive or resistant, while Riou fragments presented a medium sensitivity. Microsatellite analysis revealed that host and symbiont were genetically differentiated between sites, but not between depths. Finally, these genetic differentiations were not directly correlated to a specific thermal sensitivity whose molecular bases remain to be discovered

Symbiosis-induced adaptation to oxidative stress

Cnidarians in symbiosis with photosynthetic protists must withstand daily hyperoxic/anoxic transitions within their host cells. Comparative studies between symbiotic (Anemonia viridis) and non-symbiotic (Actinia schmidti) sea anemones show striking differences in their response to oxidative stress. First, the basal expression of SOD is very different. Symbiotic animal cells have a higher isoform diversity (number and classes) and a higher activity than the non-symbiotic cells. Second, the symbiotic animal cells of A. viridis also maintain unaltered basal values for cellular damage when exposed to experimental hyperoxia (100% O(2)) or to experimental thermal stress (elevated temperature +7 degrees C above ambient). Under such conditions, A. schmidti modifies its SOD activity significantly. Electrophoretic patterns diversify, global activities diminish and cell damage biomarkers increase. These data suggest symbiotic cells adapt to stress while non-symbiotic cells remain acutely sensitive. In addition to being toxic, high O(2) partial pressure (P(O(2))) may also constitute a preconditioning step for symbiotic animal cells, leading to an adaptation to the hyperoxic condition and, thus, to oxidative stress. Furthermore, in aposymbiotic animal cells of A. viridis, repression of some animal SOD isoforms is observed. Meanwhile, in cultured symbionts, new activity bands are induced, suggesting that the host might protect its zooxanthellae in hospite. Similar results have been observed in other symbiotic organisms, such as the sea anemone Aiptasia pulchella and the scleractinian coral Stylophora pistillata. Molecular or physical interactions between the two symbiotic partners may explain such variations in SOD activity and might confer oxidative stress tolerance to the animal host

The Response of the Mediterranean Gorgonian Eunicella singularis to Thermal Stress Is Independent of Its Nutritional Regime

International audienceOver the last few decades, sessile benthic organisms from the Mediterranean Sea have suffered from the global warming of the world's oceans, and several mass mortality events were observed during warm summers. It has been hypothesized that mortality could have been due to a nutrient (food) shortage following the stratification of the water column. However, the symbiotic gorgonian Eunicella singularis has also presented a locally exceptional mortality, despite its autotrophic capacities through the photosynthesis of its dinoflagellate symbionts. Thus, this study has experimentally investigated the response of E. singularis to a thermal stress (temperature increase from 18 to 26 degrees C), with colonies maintained more than 2 months under four nutritional diets: autotrophy only (AO), autotrophy and inorganic nitrogen addition (AN), autotrophy and heterotrophy (AH), heterotrophy only (HO). At 18 degrees C, and contrary to many other anthozoans, supplementation of autotrophy with either inorganic nitrogen or food (heterotrophy) had no effect on the rates of respiration, photosynthesis, as well as in the chlorophyll, lipid and protein content. In the dark, heterotrophy maintained the gorgonian's metabolism, except a bleaching (loss of pigments), which did not affect the rates of photosynthesis. At 24 degrees C, rates of respiration, and photosynthesis significantly decreased in all treatments. At 26 degrees C, in addition to a decrease in the lipid content of all treatments, a bleaching was observed after 1 week in the AO treatment, while the AH and AN treatments resisted three weeks before bleaching. These last results suggest that, temperatures above 24 degrees C impair the energetic reserves of this species and might explain the mortality events in the Mediterranean

Physiological response of the symbiotic gorgonian Eunicella singularis to a long-term temperature increase

9 pages, 9 figures, 2 tablesIncrease in seawater temperature is one of the major effects of global climate change that affects marine organisms, including Cnidaria. Among them, gorgonians from the NW Mediterranean Sea, such as the species Eunicella singularis, have suffered spectacular and extensive damage. We thus investigated in a controlled laboratory experiment the response of E. singularis to a long-term increase in temperature and we took a special interest in its photosynthetic and calcification response to the stress. Two populations collected at 15 and 35 m depths were studied in order to determine whether there was a difference in sensitivity to thermal stress between living depths. Our results show: (a) that calcification and photosynthesis were impacted only when gorgonians were maintained for more than two weeks at 26°C, and (b) that colonies of E. singularis living in shallow waters were less tolerant than those living in deep waters. Because E. singularis is a symbiotic species, we have also discussed the potential role of symbiosis in the thermotolerance response.This research was supported by the Government of the Principality of Monaco and the Medchange project (www.medchange.org) funded by the Agence Nationale pour la Recherche (ANR).Peer reviewe

Athlete's heart patterns in elite rugby players: effects of training specificities. [Le cœur d'athlète du joueur de rugby professionnel : effets des spécificités de l'entraînement.]

International audienceBACKGROUND: Athlete's heart patterns have been widely described. However, to our knowledge, few studies have focused on professional rugby players, who train differently according to their field position. AIM: To describe electrocardiographic and echocardiographic patterns observed in elite rugby players according to their field position. METHODS: One hundred and thirty-five professional rugby players at the end of the competitive season were included. RESULTS: According to a modified Pelliccia's classification, 68.1% of electrocardiograms were normal or had minor abnormalities, 27.2% were mildly abnormal and 3.7% were distinctly abnormal. Heart rate was higher in scrum first-row players (P<0.05). Absolute and indexed left ventricular end-diastolic internal diameters (LVIDd; absolute value 59.3±4.7 mm) exceeded 65 mm and 32 mm/m2 in 13% and 1.5% of players, respectively. Indexed LVIDd values were higher in back players (P<0.001). Left ventricular interventricular septum and posterior wall thicknesses (absolute values 9.4±1.7 mm and 9.2±1.6 mm, respectively) exceeded 13 mm in 3.7% of players. Concentric cardiac hypertrophy was noted in 3.7% of players. Except for one Wolff-Parkinson-White pattern, players with significant ECG or echocardiographic abnormalities showed no cardiovascular event or disease during follow-up. CONCLUSION: Thus, elite rugby players present similar heart patterns to elite athletes in other sports. Major electrocardiographic and echocardiographic abnormalities are quite rare. Eccentric cardiac remodelling is more frequent in back players

The Ostracod fauna from the outcroup "la falunière" of Grignon (Lutetian, Paris Basin): Stratigraphical implications

International audienceThe rehabilitation of the outcroup "la falunière" of Grignon (shell marl pit) allowed for the first time to take an almost complete section of the Paris Basin Middle Lutetian under its uncimented facies. It was the opportunity to undertake sedimentological and paleontological studies. This publication presents results of the ostracode study. More than 6000 valves or carapaces were collected and 87 species was distinguished. Three new species are described: Paracypris keiji n. sp., Neocytherideis labyrinthoidea n. sp. and Grinioneis pachycosta n. sp. The ostracodes vertical distribution in the faluns of Grignon is probably without stratigraphical signification. On the contrary, the Lutetian ostracodes associations are characteristic, as well in comparison with those of the Ypresian that with those of the Auversian or of the Barton beds. Specific diversification reflects that of the environmental niches and the wealth in individuals testify of the abundance of the food. Ostracodes indicate that the Lutetian sea was shallow, from some decimetres to some metres, probably, and its waters limpid, not much agitated. The summer temperature of water was equal at least to that of present Mediterranean Sea. From a paleogeographic point of view, the similarity between gallic fauna seems much more narrow than between whatever of this gallic fauna and those of the Aquitanian basin; so, the majority of English Lutetian species are known in the Paris Basin while the proportion of common species of the Paris Basin and of the North Aquitain basin is weak. © Publications Scientifiques du Muséum national d'Histoire naturelle, Paris