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International audience; High-throughput sequencing technologies now allow for rapid and cost-effective surveys of multiple pathogens in rodents, but it is currently unclear if the host organ chosen for screening influences the number and identity of bacteria detected. We used 16s rRNA metabarcoding to identify bacterial pathogens in the heart, liver, lungs, kidneys and spleen of 13 water voles (Arvicola terrestris) collected from two populations in Franche-Comté, France to determine if bacterial assemblages within organs are similar, if all five organs are necessary to detect all of the bacteria present in an individual animal, and if differences between the two host population’s bacterial assemblages can be detected by each organ. We identified 25 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 5.4 ± 0.7 bacteria/animal, and rarefaction analysis indicates that all five organs are required to obtain this. Organ type does not, however, influence bacterial assemblage composition in a systematic or predictable way (PERMANOVA, 999 permutations, pseudo-F4,51=1.34, p=0.12). Ordination and PERMANOVA analysis indicates that differences in pooled, liver, and lung assemblages map to host populations, but heart, kidney and spleen assemblages do not. Our results demonstrate that the number of organs sampled influences the power to detect bacterial pathogens and host-population trends in bacterial assemblage composition. These results can inform sampling decisions in public health and wildlife ecology.

P>The present study aimed to establish some basic characteristics of Atlantic bluefin tuna sperm from captive mature males, treated or untreated by gonadotropin releasing hormones agonist (GnRHa). Intratesticular milt was collected from treated and untreated fish (mean weight +/- SD: 122.9 +/- 29.2 kg, n = 21). There was no significant effect of GnRHa treatment on GSI (1.33 +/- 0.70%, n = 21) or on sperm concentration (3.8 +/- 1.3 x 1010 spermatozoa ml-1, n = 21) estimated by optical density at 260 nm. Similarly, the percentage of motile spermatozoa measured at 30 s post activation: activating medium (AM seawater containing 10 mg ml-1 BSA) was not significantly different between control and GnRHa implanted males. On the other hand, a significantly higher Average Path Velocity (VAP) was assessed for sperm from GnRHa-treated fish, compared to controls. Regardless of hormonal treatment, the percentage of motile sperm decreased after a plateau of 5-6 min post activation, and any forwardly progressing movement ceased after 10-11 min. Linear trajectories of spermatozoa were observed in seawater while tighter circles were assessed when increasing the Ca2+concentration in the AM. The storage capacity at 4 degrees C was significantly lowered when NAM (Non Activating Medium: 50% seawater containing 10 mg ml-1 BSA) was added to sperm at a 1 : 1 dilution. These results demonstrated that treatment with GnRHa had little effects (except on VAP) on sperm characteristics in captive reared Atlantic bluefin tuna. Further investigations are required to improve the knowledge of tuna sperm biology and, in this respect, the comparison between intratesticular and released sperm features should be highly informative.

National audience

The lesser Egyptian jerboa Jaculus jaculus is a desert dwelling rodent that inhabits a broad ArabianSaharan arid zone. Recently, two distant sympatric lineages were described in North-West Africa, based on morphometric and molecular data, which may correspond to two cryptic species. In the current study, phylogenetic relationships and phylogeographical structure among those lineages and geographical populations from North Africa and the Middle East were investigated. The phylogeographical patterns and genetic diversity of the cytochrome b gene (1110 bp) were addressed on 111 jerboas from 41 localities. We found that the variation in Africa is partitioned into two divergent mitochondrial clades (10.5% divergence relating to 1.654.92 Mya) that corresponds to the two cryptic species: J. jaculus and J. deserti. Diversifications within those cryptic species/clades were dated to 0.231.13 Mya, suggesting that the Middle Pleistocene climatic change and its environmental consequences affected the evolutionary history of African jerboas. The third distant clade detected, found in the Middle East region, most likely represents a distinct evolutionary unit, independent of the two African lineages.

P>The objective of this study was to complement published hake (Merlucius merlucius) sperm motility characteristics by obtention of data more specifically dependent on flagella: beat frequency, flagellar wave amplitude, wave length, number of waves along the length of the flagellum and curvature of the wave. The changes of these parameters are described in relation to the time period elapsed since activation are described using high resolution video images of flagella while quantifying the progression during the swimming period from the activity initiation to full cessation of movement several minutes later. The main characteristic of the swimming period of hake spermatozoa shows a progressive decrease of forward displacement resulting from a cumulative decrease of several activity descriptors: the beat frequency, the percentage of motile cells, the wave amplitude, the number of flagellar waves and the linearity and shape of flagella. All these parameters decrease within 7-8 min after activation in a converging fashion, which leads to full immotility. Measurements of motility parameters at different temperatures also bring additional information about energetic needs for motility of hake sperm. The wave shape of the flagella showed that: (i) the contact of flagella with sea water, not only triggers immediately its motility, but also provokes rapidly local osmotic damages such as blebs which partly impair the correct wave propagation from head vicinity to flagellar tip; (ii) fully developed waves become more and more restricted to the proximal flagellum while the tip becomes devoid of any wave; (iii) the wave amplitude decreases as a function of time during the motility period. The combination of these factors contributes to motility limitations (< 100 s) during which the spermatozoa are efficiently able to reach the egg for fertilization. Temperature effects (5-32 degrees C) on these performance characteristics were also studied; this allows to conclude that the amount of energy needed to sustain motility becomes rapidly limiting. A quantitative evaluation of all these sperm motility features leads to a better definition of the conditions for controlled propagation of this species. The motility parameters are also useful as quantitative descriptors of sperm swimming ability in situations such as: (i) varying salinity (osmolality) of the medium (swimming solution) and (ii) activating motility in seminal fluid at various dilution ratios in sea water. All together, our results lead to a better understanding of hake sperm biological features, including its sperm flagella behaviour.

P>The objective of this paper is to characterize some of the sperm motility parameters in European hake (Merluccius merluccius), which is considered to be a species with aquaculture potential. The total ATP, ADP and AMP concentrations were determined using high-performance liquid chromatography on hake sperm samples collected during the winter-early spring in the Bay of Biscay (France) (n = 22) and on hake sperm samples collected during the summer-early autumn in waters off Western Norway (n = 5). The Adenylate Energy Charge (AEC) was deduced from these data. Computer Assisted Sperm Analysis (CASA) was used to measure a series of parameters characterizing the motility and the sperm swimming performances. Changes in salinity of the swimming medium affected all the measured motility parameters. The sperm velocity and the straightness of the movement were at maximum when sperm was activated with 100% filtrated sea water (100 SW) but decreased sharply later. When sperm was activated in filtrated sea water (50% diluted with distilled water: 50 SW) the values of these parameters increased (with a lower percentage of active cells) during the first 2.5 min and thereafter decreased slowly. In 50 SW, the initial velocity was lowered but the swimming period lasting 4.5 times longer than in 100 SW (but with a lower percentage of actively swimming cells). Initial sperm motility (percentage of swimming cells) in 100 SW was affected by sperm storage duration. Undiluted sperm could be stored at 4 degrees C for 5 days and still show 13 +/- 7% motility; the velocity and straightness of the movement were at maximum at the earliest period of measurement (0.5-1 day of storage) and then decreased gradually to reach their minima after 4 days of storage. Further, both the AEC and ATP content decreased with storage time, with the AEC decreasing from 0.78 +/- 0.07 (mean +/- SD) at stripping time to 0.20 +/- 0.09 after 2 days of storage. Over the same period ATP content decreased from 85 +/- 80 to 5 +/- 4 nanomoles 10-9 spermatozoa, these data presenting a high variability.

P>The development of cheaper technical tools and the availability of well established assay kits provide today the spermatologists with several devices for objective and quantifying assessment of sperm quality. The present paper reviews modern methods on sperm concentration assessment, morphometry, motility processes through flagellum studies, motility objective assessment by computer assisted sperm analysis (CASA), sperm integrity and energetic state measurements.

Correspondance: benfalahabdelraouf@yahoo.fr; International audience; Jerboas belonging to the genus Jaculus are widely distributed rodents inhabiting Palearctic desert and semi-desert areas. Previous studies on the lesser Egyptian jerboa Jaculus jaculus showed the existence of various morphological forms of controversial taxonomic status. They were sometimes related to two different species, J. jaculus and Jaculus deserti, although this has not been recognized in recent taxonomic updates. To clarify the systematic status of J. jaculus in Tunisia, we performed molecular (phylogenetic analyses of cytochrome b sequences), morphological (multivariate analyses of 13 skull measurements) and karyotypic (standard preparations from bone marrow cells) analyses on a number of specimens mean collected from ten localities. Our analyses revealed two monophyletic, well differentiated clades, with a genetic divergence value (K2P = 10.9 +/- 0.01%), which is within the range of distances generally observed between rodent species. Morphometric analyses clearly separated populations of the two genetic clades from each other. However, karyotypes of individuals from both clades appeared similar. Individuals from both molecular clades/morphometric groups were found in sympatry in most of the localities sampled. These results, as obtained from a restricted area of the total distribution, suggest that there are two separate species within the currently accepted J. jaculus in Tunisia. Alternative hypotheses such as the occurrence of a strong, ancient phylogeographic structure, or the presence of pseudogenes, are also considered to account for the results obtained