Consequences of organ choice in describing bacterial pathogen assemblages in a rodent population.

High-throughput sequencing technologies now allow for rapid cost-effective surveys of multiple pathogens in many host species including rodents, but it is currently unclear if the organ chosen for screening influences the number and identity of bacteria detected. We used 16S rRNA amplicon sequencing to identify bacterial pathogens in the heart, liver, lungs, kidneys and spleen of 13 water voles (Arvicola terrestris) collected in Franche-Comté, France. We asked if bacterial pathogen assemblages within organs are similar and if all five organs are necessary to detect all of the bacteria present in an individual animal. We identified 24 bacteria representing 17 genera; average bacterial richness for each organ ranged from 1·5 ± 0·4 (mean ± standard error) to 2·5 ± 0·4 bacteria/organ and did not differ significantly between organs. The average bacterial richness when organ assemblages were pooled within animals was 4·7 ± 0·6 bacteria/animal; Operational Taxonomic Unit accumulation analysis indicates that all five organs are required to obtain this. Organ type influences bacterial assemblage composition in a systematic way (PERMANOVA, 999 permutations, pseudo-F 4,51 = 1·37, P = 0·001). Our results demonstrate that the number of organs sampled influences the ability to detect bacterial pathogens, which can inform sampling decisions in public health and wildlife ecology.

Atlas of macroseismic maps for French earthquakes with their principal characteristics

The SIRENE macroseismic database has been utilized to draw isoseismal maps for the 140 best-documented French earthquakes, characterized by epicentral intensities of at least V(MSK) and located in all parts of the country. A study of focal depths derived from available local intensity data using an intensity versus distance decay law (Sponheuer) shows that the focal depths of most of the events considered do not exceed about 10 km. Thier distribution correlates fairly well with regional dynamic geology features. A relationship is then computed between magnitude, intensity and focal distance, based on 73 instrumentally recorded earthquakes (Ml between 3.3 and 6.3) and on 217 mean radius values (from 2 to 380 km) for isoseismals of intensity VIII to III (MSK). This relationship is applied to historical earthquakes contained in the database SIRENE which are characterised by their intensity only. These results are used in the evaluation as well deterministic as probabilistic of the seismic hazard on the national territory.(AU)