Dispersal in Mastomys natalensis mice: use of fine-scale genetic analyses for pest management

Mastomys natalensis is the major pest rodent in sub-Saharan Africa. In this study, population genetic techniques were used to gain new insights into its dispersal behaviour, a critical parameter in pest management. Using 11 microsatellites, 272 individuals from a 300 ha area in Tanzania were genotyped. Genetic diversity was high, with no isolation by distance and little differentiation between field plots far apart, indicating a large effective population size and high dispersal rates in agreement with ecological observations. On the other hand, genetic differentiation between nearby field plots, isolation by distance within a single field plot and kin clustering were also observed. This apparent contradiction may be explained by yearly founder effects of a small number of breeding individuals per square area, which is consistent with the presence of linkage disequilibrium. An alternative, not mutually exclusive explanation is that there are both dispersing and sedentary animals in the population. The low-density field plots were characterized by low relatedness and small genetic distances to other field plots, indicating a high turnover rate and negative density-dependent dispersal. In one field plot female-biased dispersal was observed, which may be related to inbreeding avoidance or female competition for resources. Most juveniles appeared to be local recruits, but they did not seem to stay in their native area for more than two months. Finally, possible implications for pest management are discusse

A multi-approach survey as the most reliable tool to accurately assess biodiversity: an example of thai murine rodents

Wildlife surveys rely on an accurate taxonomic framework. Identification tools used to reach this goal are not equivalent and may depend on several objectives and constraints, including sampling conservation difficulties, the invasiveness of the sampling techniques, sampling capacity, the relevance of the results, materials needed, the cost and the user time required in the field and laboratory. This article presents and discusses the advantages and limits of each identification tool used in the Ceropath (Community ecology of rodents and their pathogens in South East Asia) program to reach a fast and relevant identification of the rodents sampled. It is concluded that there needs to be a combination of the results from different methods, including the most recent ones, to achieve an improvement in taxonomic identification

Simulation des mobilités pelviennes : optimisation topologique du système ligamentaire

Le prolapsus génital féminin est un phénomène encore mal compris avec un taux d'échec des techniques chirurgicales élevé (de 10 à 40%). Nous proposons un modèle 3D de la cavité pelvienne construit à partir d'images IRM d'une patiente saine. Les résultats numériques sont comparés avec des analyses de champs de déplacements issus d images IRM dynamiques de la même patiente en effort de poussée. L'introduction progressive des ligaments et des conditions aux limites tout en quantifiant l'écart à la réalité nous mène vers un modèle cohérent permettant une étude de sensibilité

Taxon Appearance From Extraction and Amplification Steps Demonstrates the Value of Multiple Controls in Tick Microbiota Analysis

Background: The development of high-throughput sequencing technologies has substantially improved analysis of bacterial community diversity, composition, and functions. Over the last decade, high-throughput sequencing has been used extensively to identify the diversity and composition of tick microbial communities. However, a growing number of studies are warning about the impact of contamination brought along the different steps of the analytical process, from DNA extraction to amplification. In low biomass samples, e.g., individual tick samples, these contaminants may represent a large part of the obtained sequences, and thus generate considerable errors in downstream analyses and in the interpretation of results. Most studies of tick microbiota either do not mention the inclusion of controls during the DNA extraction or amplification steps, or consider the lack of an electrophoresis signal as an absence of contamination. In this context, we aimed to assess the proportion of contaminant sequences resulting from these steps. We analyzed the microbiota of individual Ixodes ricinus ticks by including several categories of controls throughout the analytical process: homogenization, DNA extraction, and DNA amplification. Results: Controls yielded a significant number of sequences (1, 126–13, 198 mean sequences, depending on the control category). Some operational taxonomic units (OTUs) detected in these controls belong to genera reported in previous tick microbiota studies. In this study, these OTUs accounted for 50.9% of the total number of sequences in our samples, and were considered contaminants. Contamination levels (i.e., the percentage of sequences belonging to OTUs identified as contaminants) varied with tick instar and sex: 76.3% of nymphs and 75% of males demonstrated contamination over 50%, while most females (65.7%) had rates lower than 20%. Contamination mainly corresponded to OTUs detected in homogenization and extraction reagent controls, highlighting the importance of carefully controlling these steps. Conclusion: Here, we showed that contaminant OTUs from sample laboratory processing steps can represent more than half the total sequence yield in sequencing runs, and lead to unreliable results when characterizing tick microbial communities. We thus strongly advise the routine use of negative controls in tick microbiota studies, and more generally in studies involving low biomass samples

Study of pufferfish (Takifugu niphobles) sperm: development of methods for short-term storage, effects of different activation media and role of intracellular changes in Ca2+ and K+ in the initiation of sperm motility

[EN] The first goal of this study was the development of a short-term storage method for pufferfish (Takifugu niphobles) sperm. In this respect, the best results were obtained by diluting the sperm in a seminal-like solution and keeping it in a Petri dish in chilled storage (4 degrees C). This method was successful in preserving sperm quality parameters without resulting in differences in fresh sperm for a relatively long-term period (7 days), for use in aquaculture matters. The addition of bovine serum albumin (BSA) to the medium did not improve the results. On the other hand, both the osmolality and the ion composition of the media are essential factors which can modulate the sperm motility parameters. The osmolality of the activating medium was the most important factor in triggering pufferfish sperm motility, and osmolalities of 750-825 mOsm/kg were necessary to initiate this process, demonstrating that it appears to be a dose-independent mechanism. Regarding the ion composition of the activation media, this study has shown that despite the spermatozoa being able to initiate movement without any ion in the activation medium, the absence of ions can negatively affect the kinetic parameters of the spermatozoa. Finally, in natural conditions (seawater), the activation of sperm motility generates intracellular increases in Ca2+ and K+, suggesting that these ions play an essential role in the activation mechanism of pufferfish sperm. (C) 2013 Elsevier B.V. All rights reserved.This study was funded by the Spanish Ministry of Science and Innovation (MICINN; AGL2010-16009). Victor Gallego has a predoctoral grant (MICINN; BES-2009-020310) and has been granted a fellowship (EEBB-I-12-05858) from the Spanish Personnel Research Training Programme to carry out this study in the Misaki Marine Biological Station (Miura, Japan).Gallego Albiach, V.; Pérez Igualada, LM.; Asturiano Nemesio, JF.; Yoshida, M. (2013). Study of pufferfish (Takifugu niphobles) sperm: development of methods for short-term storage, effects of different activation media and role of intracellular changes in Ca2+ and K+ in the initiation of sperm motility. Aquaculture. 414:82-91. https://doi.org/10.1016/j.aquaculture.2013.07.046S829141

Intracellular changes in Ca2+, K+ and pH after sperm motility activation in the European eel (Anguilla anguilla): Preliminary results

[EN] Although it is widely accepted that osmolality and ion fluxes are the main factors triggering sperm motility in fish, a complex universal mechanism for sperm motility activation does not exist in fish, and studies of marine fish species are even more scarce. Therefore, the main goal of this study was to estimate the intracellular variations in the main ions involved in sperm activation for the first time in European eel, in order to provide additional new data about this little-known process. It was observed that levels of intracellular Ca2+ and K+ sperm ions increased significantly 30 s after the hyperosmotic shock compared to baseline levels, and remained at this level until 120 s post-activation. In contrast, the intracellular pH remained constant during the first 30 s, and decreased gradually at 60 and 120 s post-activation. Our data agree with the current main theory for explaining motility activation in marine fish, in which internal fluctuations of Ca2+ and K+ seem to participate in sperm activation. In addition, fluorescent images showed that both Ca2+ and K+ were concentrated in the apical area of the sperm head, which corresponds to the location of the eel sperm mitochondria, suggesting this organelle plays an important role in sperm motility activation. (C) 2013 Elsevier B.V. All rights reserved.Funded from the European Community's 7th Framework Programme under the Theme 2 "Food, Agriculture and Fisheries, and Biotechnology", grant agreement no 245257 (Pro-Eel) and the Spanish Ministry of Science and Innovation (MICINN; AGL2010-16009). Victor Gallego has a predoctoral grant (MICINN; BES-2009-020310) and has been granted a fellowship (EEBB-I-12-05858) of the Spanish Personnel Research Training Programme to carry out this study in the Universidad de Leon (Leon, Spain). Ilaria Mazzeo had a predoctoral grant from GVA. David S. Penaranda has a contract co-financed by MICINN and UPV (PTA2011-4948-I). F. Martinez-Pastor was supported by the Ramon y Cajal program (RYC-2008-02560, MICINN).Gallego Albiach, V.; Martínez Pastor, F.; Mazzeo, I.; Peñaranda, D.; Herraez, P.; Asturiano Nemesio, JF.; Pérez Igualada, LM. (2014). Intracellular changes in Ca2+, K+ and pH after sperm motility activation in the European eel (Anguilla anguilla): Preliminary results. Aquaculture. 418:155-158. https://doi.org/10.1016/j.aquaculture.2013.10.022S15515841

Sperm motility parameters and spermatozoa morphometric characterization in marine species: a study of swimmer and sessile species

[EN] The biodiversity of marine ecosystems is diverse and a high number of species coexist side by side. However, despite the fact that most of these species share a common fertilization strategy, a high variability in terms of the size, shape, and motion of spermatozoa can be found. In this study, we have analyzed both the sperm motion parameters and the spermatozoa morphometric features of two swimmer (pufferfish and European eel) and two sessile (sea urchin and ascidian) marine species. The most important differences in the sperm motion parameters were registered in the swimming period. Sessile species sperm displayed notably higher values than swimmer species sperm. In addition, the sperm motilities and velocities of the swimmer species decreased sharply once the sperm was activated, whereas the sessile species were able to maintain their initial values for a long time. These results are linked directly to the species-specific lifestyles. Although sessile organisms, which show limited or no movement, need sperm with a capacity to swim for long distances to find the oocytes, swimmer organisms can move toward the female and release gametes near it, and therefore the spermatozoa does not need to swim for such a long time. At the same time, sperm morphology is related to sperm motion parameters, and in this study an in-depth morphometric analysis of ascidian, sea urchin, and pufferfish spermatozoa, using computer-assisted sperm analysis software, has been carried out for the first time. A huge variability in shapes, sizes, and structures of the studied species was found using electron microscopy. (C) 2014 Elsevier Inc. All rights reserved.This study was funded by the Spanish Ministry of Science and Innovation (MICINN; AGL2010-16009). Victor Gallego has a predoctoral grant (MICINN; BES-2009-020310) and has been granted a fellowship (EEBB-I-12-05858) of the Spanish Personnel Research Training Program to carry out this research in the Misaki Marine Biological Station (Miura, Japan).Gallego Albiach, V.; Pérez Igualada, LM.; Asturiano Nemesio, JF.; Yoshida, M. (2014). Sperm motility parameters and spermatozoa morphometric characterization in marine species: a study of swimmer and sessile species. Theriogenology. 82(5):668-676. https://doi.org/10.1016/j.theriogenology.2014.05.026S66867682

Temporal patterns in Ixodes ricinus microbial communities: an insight into tick-borne microbe interactions

Background: Ticks transmit pathogens of medical and veterinary importance and are an increasing threat to human and animal health. Assessing disease risk and developing new control strategies requires identifying members of the tick-borne microbiota as well as their temporal dynamics and interactions. Methods: Using high-throughput sequencing, we studied the Ixodes ricinus microbiota and its temporal dynamics. 371 nymphs were monthly collected during three consecutive years in a peri-urban forest. After a Poisson lognormal model was adjusted to our data set, a principal component analysis, sparse network reconstruction, and differential analysis allowed us to assess seasonal and monthly variability of I. ricinus microbiota and interactions within this community. Results: Around 75% of the detected sequences belonged to five genera known to be maternally inherited bacteria in arthropods and to potentially circulate in ticks: Candidatus Midichloria, Rickettsia, Spiroplasma, Arsenophonus and Wolbachia. The structure of the I. ricinus microbiota varied over time with interannual recurrence and seemed to be mainly driven by OTUs commonly found in the environment. Total network analysis revealed a majority of positive partial correlations. We identified strong relationships between OTUs belonging to Wolbachia and Arsenophonus, evidence for the presence of the parasitoid wasp Ixodiphagus hookeri in ticks. Other associations were observed between the tick symbiont Candidatus Midichloria and pathogens belonging to Rickettsia. Finally, more specific network analyses were performed on TBP-infected samples and suggested that the presence of pathogens belonging to the genera Borrelia, Anaplasma and Rickettsia may disrupt microbial interactions in I. ricinus. Conclusions: We identified the I. ricinus microbiota and documented marked shifts in tick microbiota dynamics over time. Statistically, we showed strong relationships between the presence of specific pathogens and the structure of the I. ricinus microbiota. We detected close links between some tick symbionts and the potential presence of either pathogenic Rickettsia or a parasitoid in ticks. These new findings pave the way for the development of new strategies for the control of ticks and tick-borne diseases. [MediaObject not available: see fulltext.] © 2021, The Author(s)

Standardization of European eel (Anguilla anguilla) sperm motility evaluation by CASA software

[EN] The development of powerful computer-assisted sperm analysis software has made kinetic studies of spermatozoa possible. This system has been used and validated for several species, but some technical questions have emerged regarding fish sample evaluations (i.e., frame rate, sperm dilution, chamber model, time of analysis, magnification lens, etc.). In the present study, we have evaluated the effects of different procedural and biological settings with the aim to correctly measure sperm quality parameters of the European eel. The use of different chambers did not affect the sperm motility parameters. However, regarding lens magnification, 10x was the most accurate lens, showing the least variation in the acquired data. Similarly, the frame rate setting resulted in a dramatic effect in some sperm kinetic parameters, primarily in terms of curvilinear velocity; we therefore recommend using the camera's highest available frame rate setting. Finally, the reduction in sperm motility over postactivation times suggests that sperm analysis should be performed within the first 60 seconds after activation of the European eel sperm. In conclusion, some protocol variables of sperm analysis by computer-assisted sperm analysis software can affect the measurement of eel sperm quality parameters, and should be considered before directly comparing results obtained by different laboratories. Moreover, because marine fish species show relatively similar features of sperm kinetic parameters, these results could be considered in the evaluation of the motility of sperm from other fish species. (C) 2013 Elsevier Inc. All rights reserved.This study was funded from the European Community's 7th Framework Programme under the Theme 2 "Food, Agriculture and Fisheries, and Biotechnology," grant agreement 245257 (Pro-Eel), and Generalitat Valenciana (ACOMP/2011/229). D.S.P. and P.C.F.C. have postdoctoral grants from UPV (CE-01-10) and PAC-EMBRAPA, respectively. I.M. and V.G. have predoctoral grants from Generalitat Valenciana and Spanish MICINN, respectively. The authors thank the Proiser R&D, S.L. team, who performed the task of fractioning the original sequences for the experiment described in section 3.2.Gallego Albiach, V.; Carneiro, PCF.; Mazzeo, I.; Vilchez Olivencia, MC.; Peñaranda, D.; Soler, C.; Pérez Igualada, LM.... (2013). Standardization of European eel (Anguilla anguilla) sperm motility evaluation by CASA software. Theriogenology. 79(7):1034-1040. https://doi.org/10.1016/j.theriogenology.2013.01.019S1034104079

Taxonomic status and origin of the shrews (Soricidae) from the Canary islands inferred from a mtDNA comparison with the European Crocidura species.

European island shrews are either relicts of the endemic Pleistocene fauna, e.g.,. Crocidura zimmermanni, or were introduced from continental source populations. In order to clarify the taxonomic status and the origin of the two shrew species from the Canary islands, a 981bp fragment of cytochrome b gene was investigated in all European Crocidura species and compared with the Canary shrew (Crocidura canariensis) and the Osorio shrew (Crocidura osorio). The first shares its karyotype with the Sicilian shrew Crocidura sicula (2N=36), the second with the Greater white-toothed shrew Crocidura russula (2N=42), suggesting possible sister species relationships. Results confirm the monophyly of taxa sharing the same karyotype. Genetic distances between C. sicula and C. canariensis suggest a separation since 5 Myr. The first was probably isolated from the North African ancestor after the Messinian desiccation; the second arrived on the Canary islands by natural jump dispersal. Within the 2N=42 cluster, a first split separated an Eastern line (Tunisia) from a western line (Morocco/Europe) of C. russula. C. osorio clusters together with C. russula from Spain, indicating conspecificy. This suggests a recent introduction from Spain by human