Spatio-temporal patterns in arctic fox (Vulpes alopex) diets revealed by molecular analysis of scats from Northeast Greenland

The arctic fox (Vulpes lagopus) is endemic to the Arctic where it holds a central position in the trophic interactions. The diet of the species has previously been described as being highly flexible, but whether this flexibility is a constant trait through time, or merely reflects fast temporal changes in abundance among prey taxa, has so far been poorly resolved. Using molecular analyses of arctic fox scats from Northeast Greenland, we first examined the temporal dynamics of arctic fox diets during the short snow-free season, and then examined whether local food availability at different sites affected arctic fox dependence on lemmings. Arctic fox diets included most terrestrial vertebrate species found in the region, and exhibited substantial temporal changes, generally reflecting the dynamic changes in prey availability from late winter through autumn. This dietary flexibility was also reflected geographically, with arctic foxes consuming a variety of local prey (mainly waterfowl and lemmings) in summer. Moreover, the dietary response of arctic foxes to changes in lemming abundance depended on access to non-lemming prey. Based on these findings, we discuss whether varying degrees of lemming-dependency, combined with geographical differences in winter food availability, may explain previously published differences in arctic fox breeding patterns in high arctic Greenland.Peer reviewe

Spatio-temporal patterns in arctic fox (Vulpes alopex) diets revealed by molecular analysis of scats from Northeast Greenland

The arctic fox (Vulpes lagopus) is endemic to the Arctic where it holds a central position in the trophic interactions. The diet of the species has previously been described as being highly flexible, but whether this flexibility is a constant trait through time, or merely reflects fast temporal changes in abundance among prey taxa, has so far been poorly resolved. Using molecular analyses of arctic fox scats from Northeast Greenland, we first examined the temporal dynamics of arctic fox diets during the short snow-free season, and then examined whether local food availability at different sites affected arctic fox dependence on lemmings. Arctic fox diets included most terrestrial vertebrate species found in the region, and exhibited substantial temporal changes, generally reflecting the dynamic changes in prey availability from late winter through autumn. This dietary flexibility was also reflected geographically, with arctic foxes consuming a variety of local prey (mainly waterfowl and lemmings) in summer. Moreover, the dietary response of arctic foxes to changes in lemming abundance depended on access to non-lemming prey. Based on these findings, we discuss whether varying degrees of lemming-dependency, combined with geographical differences in winter food availability, may explain previously published differences in arctic fox breeding patterns in high arctic Greenland.Peer reviewe

Effects of the cestode parasite, Cyathocephalus truncatus, on the fecundity and feeding rate of Gammarus pulex (Crustacea: Amphipoda)

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Dissemination of CTX-M-producing Escherichia coli in freshwater fishes from a french watershed (Burgundy)

International audienceThe burden of extended-spectrum beta-lactamases producing Escherichia coli (ESBL-Ec), has increased over several decades. Freshwater ecosystems are suspected to play an important ecological and evolutionary role in driving the dissemination of antimicrobial resistance. The aim of our study was to decipher the occurrence of ESBL-Ec in a small watershed (Ouche river, Burgundy, France), targeting environmental matrices and fishes. Among cefotaxime resistant E. coli (ctxR Ec) isolates, we detected and characterized 36 ESBL-Ec from water, biofilm and fish guts. ctxR Ec and ESBL-Ec were found in samples from sites near the first small town, located downstream from the watershed which was studied. Treatment of urban wastewater by waste water treatment plants (WWTP), might therefore be a major potential source of ctxR Ec and thus of ESBL-Ec. Prevalence of total E. coli and ctxR Ec in fish guts ranged between 0 to 92% and 0 to 85%; respectively, depending on the sampling site and the fish species. The diet of fish (predator or omnivore) seems to strongly influence the prevalence of total E. coli and ESBL-Ec. Extended spectrum beta-lactamases produced by the isolates from this study belonged to the CTX-M family (CTX-M group 1 and 9). Moreover, some environmental ESBL-Ec proved to share genotypic features (MLST types) with isolates which originated from 8 WWTP effluents discharged in the Ouche river and with the sequence type ST131, which is widely described in clinical isolates. Ninety-seven % (97%) of ESBL-Ec from the study harbored additional antibiotic resistances and can thus be considered as multi drug resistant (MDR) bacteria. Finally, 53% of the ESBL-Ec strains harbored class 1 integron-integrase (intl1). These results are discussed with the perspective of defining indicators of antibiotic resistance contamination in freshwater ecosystems

The effects of two acanthocephalan parasites, Pomphorhynchus laevis and Polymorphus minutus, on pairing success in male Gammarus pulex (Crustacea: Amphipoda)

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A nitrocefin-based amperometric assay for the rapid quantification of extended-spectrum β-lactamase-producing Escherichia coli in wastewaters

International audienceA sensitive and inexpensive amperometric assay based on the electrochemical detection of the beta-lactamase activity using the nitrocefin as substrate was developed for the rapid and quantitative detection of extended spectrum beta-lactamase-producing Escherichia colt (ESBL-EC) in urban wastewaters. The specific detection of ESBL-EC was achieved by culturing the filtered sample in a medium containing the cefotaxime supplemented or not with the potassium clavulanate inhibitor. This step was followed by the incubation of each subculture filtrate with the nitrocefin substrate which hydrolysis was monitored by amperometry using disposable carbon screen-printed sensors. Current intensities i(Cef) and i(Clav) correspond to the intensity of the anodic current measured (similar to+ 0.2 V vs. Ag/AgCl) for the sample incubated with the cefotaxime without and with potassium clavulanate, respectively. The intensity value i = i(Cef) iClav was chosen as the analytical response. ESBL-EC calibration plots were established with artificially contaminated wastewater samples. This assay allowed the detection of ESBL-EC amounts as low as 10 cfu in treated effluents and 100 cfu in raw wastewaters with short time analysis of 5.5 h and 4.5 h, respectively. The amperometric method was applied to the analysis of 38 wastewater samples and the results were in good agreement with CFU counts on a selective chromogenic medium for 24 h. Owing to its rapidity, convenience, low-cost and portability, this assay is a promising tool to obtain quantitative data on antimicrobial-resistant E. coli in wastewater effluents. Furthermore, this assay might be used to improve wastewater treatment plant processes in order to minimize the release of antibiotic resistant bacteria into the aquatic environment

Rapid dissemination of Mycobacterium bovis from cattle dung to soil by the earthworm Lumbricus terrestris

International audienceIndirect transmission of Mycobacterium bovis, the causative agent of bovine tuberculosis (bTB), between wildlife and livestock is thought to occur by inhalation or ingestion of environmental substrates contaminated through animal shedding. The role of the soil fauna, such as earthworms, in the circulation of M. bovis from contaminated animal feces is of interest in the epidemiology of bTB. The objective of this study was to assess the impact of earthworm activity on M. bovis transfer from animal dung to castings and the surrounding soil. For this purpose, microcosms of soil containing the anecic eathworms Lumbricus terrestris were prepared and covered with cattle feces spiked with the M. bovis BCG strain Pasteur to carry out two separate experiments. The dissemination, the gut carriage and the excretion of M. bovis were all monitored using a specific qPCR-based assay. Our results showed that the earthworm L. terrestris was able to rapidly disseminate M. bovis from the contaminated cattle feces to the surrounding soil through casting egestion. Moreover, contaminated earthworms were shown to shed the bacteria for 4 days when transferred to a M. bovis-free soil. This study highlights for the first time the possible role of earthworms in the dissemination and the persistence of M. bovis in soils within bTB endemic areas