Changes in benthic macrofauna in oyster parks during an OsHV-1 μVar oyster spat mortality outbreak

International audienceIn intertidal areas, oyster farming creates a crosshatching pattern between oyster tables and aisles. Tables provide a refuge from the current and solar irradiance and the oysters facilitate the accumulation of OM, thereby structuring the spatial organization of the associated macrozoobenthic community at mesoscale. The aim of this study was to describe the quality of the oyster table environment at small scale and the response of the macrozoobenthic community to OsHV-1 µvar oyster mortality. The species assemblage was dominated by Golfingia vulgaris, Tubificoides benedii, Capitella capitata and Scoloplos armiger. The table habitat appeared to be in a bad ecological state throughout the 2-month survey (May and June 2017), whereas in the aisle, eutrophication occurred lately and was clearly related to be due to the massive stranding of dead seaweed at the end of the survey (in early July). So, this disturbance of the species assemblage seemed to occur in two phases: 1) after oyster spat mortality and 2) after seaweed stranding resulted in a bad ecological status, as revealed by macrofaunal indicators. Large quantities of OsHV-1 DNA were also found in some species, including small crabs and amphipods, one week after the mortality crisis, but there is no apparent virus reservoir found in the benthic species

A Quantitative Histologic Analysis of Oogenesis in the Flatfish Species Pleuronectes platessa as a Tool for Fisheries Management

The following paper gives a detailed description of the oogenesis cycle for the European Plaice (Pleuronectes platessa), from oogonia to post-ovulatory follicle, including ovarian follicle and zona pellucida sizes. Noteworthy particularities were the difficulty in identifying cortical alveoli due to their very small size. Quantitative histology (stereology) on histological slides was used to determine a first size at maturity for females from the English Channel, which was found to be smaller compared to the literature (19 cm). Stereology also determined a first spawning event starting in January, with a peak in February and ongoing until March. Moreover, the use of stereology showed misclassifications for individuals categorized into a maturity phase using a macroscopic visual method. Misclassifications were found with individuals that had spawned (D) but were put under the immature (A) phase, and individuals in development (B) classified under D

Male triploid oysters of Crassostrea gigas exhibit defects in mitosis and meiosis during early spermatogenesis

International audienceThe Pacific oyster, Crassostrea gigas is a successive irregular hermaphrodite mollusc which has an annual breeding cycle. Oysters are naturally diploid organisms, but triploid oysters have been developed for use in shellfish aquaculture, with the aim of obtaining sterile animals with commercial value. However, studies have shown that some triploid oysters are partially able to undergo gametogenesis, with numerous proliferating cells closed to diploids (3n alpha) or a partial one with an accumulation of locked germ cells (3n beta). The aim of our study therefore was to understand the regulation of spermatogenesis in both groups of triploid oysters (alpha and beta) from the beginning of spermatogenesis, during mitosis and meiosis events. Our results demonstrate that the reduced spermatogenesis in triploids results from a deregulation of the development of the germinal lineage and the establishment of the gonadal tract led by a lower number of tubules. Morphological cellular investigation also revealed an abnormal condensation of germ cell nuclei and the presence of clear patches in the nucleoplasm of triploid cells, which were more pronounced in beta oysters. Furthermore, studies of molecular and cellular regulation showed a downregulation of mitotic spindle checkpoint in beta oysters, resulting in disturbance of chromosomal segregation, notably on Spindle Assembly Checkpoint involved in the binding of microtubules to chromosomes. Taken together, our results suggest that the lower reproductive ability of triploid oysters may be due to cellular and molecular events such as impairment of spermatogenesis and disruptions of mitosis and meiosis, occurring early and at various stages of the gametogenetic cycle

An objective take on defining sexual maturity in the plaice, Pleuronectes platessa (Linné, 1758)

The European plaice (Pleuronectes platessa) is a commercial species with stock management advice given through the estimation of fish length at maturity (L50) (Mahé et al., 2007). Estimating the maturity of fish species has been worked on by the International Council for the Exploration of the Sea (ICES) that wants to harmonize the definitions, terminologies and practices used to determine the different maturity phases. Project MATO (MATurité Objective des poissons par l’histologie quantitative) will, among other things, bring knowledge on the ovarian histology of the plaice in order to correlate histological maturity with macroscopic parameters like the size color and texture of the ovaries. With this knowledge, the aim of this study is to set up a protocol that will help define the different maturity phases of Pleuronectes platessa in a completely objective way while following the ICES (2018) maturity scale

A macroscopic and stereological imaging dataset of Pleuronectes platessa ovaries

The North Sea plaice, Pleuronectes platessa (Linnaeus, 1758), is a commonly studied commercial flatfish with poorly known ovarian histology. The following dataset is a collection of female plaice gonad images and their corresponding histological slides, collected during a complete season of the plaice’s reproduction cycle. Stereology was used to determine the percentage of different structures found throughout the ovaries. Inter-agent calibrations were accomplished in order to harmonize the stereological readings, and were based on a comprehensive reading protocol and histological lexicon that were specifically written for the plaice’s ovaries. The distribution and homogeneity of the different cell types found throughout the ovaries were also evaluated. This dataset can be used to automate the stereological reading process (through statistical learning methods for example) or to objectively determine the plaice’s maturity phase, and link that information to either macroscopic measurements or through image analysis of the full ovaries

Gonadal transcriptomes associated with sex phenotypes provide potential male and female candidate genes of sex determination or early differentiation in Crassostrea gigas, a sequential hermaphrodite mollusc

Background In the animal kingdom, mollusca is an important phylum of the Lophotrochozoa. However, few studies have investigated the molecular cascade of sex determination/early gonadal differentiation within this phylum. The oyster Crassostrea gigas is a sequential irregular hermaphrodite mollusc of economic, physiological and phylogenetic importance. Although some studies identified genes of its sex-determining/−differentiating pathway, this particular topic remains to be further deepened, in particular with regard to the expression patterns. Indeed, these patterns need to cover the entire period of sex lability and have to be associated to future sex phenotypes, usually impossible to establish in this sequential hermaphrodite. This is why we performed a gonadal RNA-Seq analysis of diploid male and female oysters that have not changed sex for 4 years, sampled during the entire time-window of sex determination/early sex differentiation (stages 0 and 3 of the gametogenetic cycle). This individual long-term monitoring gave us the opportunity to explain the molecular expression patterns in the light of the most statistically likely future sex of each oyster. Results The differential gene expression analysis of gonadal transcriptomes revealed that 9723 genes were differentially expressed between gametogenetic stages, and 141 between sexes (98 and 43 genes highly expressed in females and males, respectively). Eighty-four genes were both stage- and sex-specific, 57 of them being highly expressed at the time of sex determination/early sex differentiation. These 4 novel genes including Trophoblast glycoprotein-like, Protein PML-like, Protein singed-like and PREDICTED: paramyosin, while being supported by RT-qPCR, displayed sexually dimorphic gene expression patterns. Conclusions This gonadal transcriptome analysis, the first one associated with sex phenotypes in C. gigas, revealed 57 genes highly expressed in stage 0 or 3 of gametogenesis and which could be linked to the future sex of the individuals. While further study will be needed to suggest a role for these factors, some could certainly be original potential actors involved in sex determination/early sex differentiation, like paramyosin and could be used to predict the future sex of oysters

Stereology reading protocol when using quantitative histology for the determination of sexual maturity in fish ovaries

This protocol was established for the evaluation of sexual maturity for exploited stock species, using quantitative histology (stereology). This document describes the reading method used on histological slides under the cross-platform QuPath.           This document follows the work of different workshops that aimed to improve the compilation of data on sexual maturity. The WKMATCH (WorKshop for MATurity staging CHairs, 2012) and the WKASMSF (Workshop for Advancing Sexual Maturity Staging in Fish, 2018) defined a universal evaluation grid for sexual maturity staging of different species, including teleosteans. During the WKMATCH workshop, two main recommendations were made, underlining the need to improve and complete knowledge on sexual maturity, as well as to harmonize the practices used to determine these sexual phases.           Another workshop, the WKMATHIS (WorKshop on sexual MATurity staging from HIStological tools) that took place in Caen in 2017, added new objectives : review the current knowledge on gonad histology, determine a sexual maturity scale at a cellular level, and histological studies should be made in order to improve the determination of sexual maturity on a macroscopic scale.            This protocol, drawn from these workshops and their conclusions, offers guidelines on how to read histological slides through the use of stereology. As of June 2022, this protocol is linked to the MATO (MATurité Objectif des poissons par l’histologie quantitative) project, a study restricted to female gonad and the different cellular structures found inside the ovaries for different species (Pleuronectes platessa, Lepidorhombus whiffiagonis, Lepidorhombus boscii, Mullus surmuletus and Micromesistius poutassou).           This protocol will present reading methods that favor an objective reading of histological slides, through stereology, and will allow less experienced readers to partake in this exercise. For a detailed description of the germinal cells, refer to the lexicon of the studied speci

Note d’appui scientifique et technique de l’Anses relative au projet de décret relatif à l’information sur les produits de protection intime

Citation suggérée : Anses. (2022). Note d’appui scientifique et technique de l'Anses relative au projet de décret relatif à l’information sur les produits de protection intime. (saisine 2022-SA-0106). Maisons-Alfort : Anses, 22 p.En 2019, l’Anses a publié un avis et un rapport sur la sécurité des protections intimes (Anses, 2019). Cette expertise n’a pas mis en évidence de préoccupation sanitaire liée aux substances chimiques présentes dans ces produits. Cependant, le principal risque documenté lié au portde protections intimes internes (tampon, coupe menstruelle) est le syndrome de choc toxique menstruel (SCT) qui, bien que rare, peut entrainer de graves conséquences sur la santé des femmes qui en sont victimes. Les protections intimes externes (serviettes, protège-slips) n’ontjamais été impliquées dans le SCT menstruel. Depuis cette expertise, des actions ont été mises en œuvre par le Gouvernement afin d’inciterles industriels à mettre en place des autocontrôles périodiques des produits et à améliorer leur processus d’approvisionnement et de fabrication de façon à supprimer ou limiter autant que possible la présence de substances chimiques préoccupantes (HAP, dioxines, furanes, phtalates, pesticides notamment). D’autre part, des contrôles périodiques ont été diligentés sur ces produits par la DGS et la DGCCRF dont les derniers résultats d’enquête sur les nouveaux produits de protection intime (serviettes réutilisables ou culottes menstruelles, tampons à usage unique dits « biologiques » ou réutilisables) ont été publiés en mars 2022. La DGCCRF et la DGS ont rédigé conjointement un projet de décret qui vise à renforcer laprotection et l’information des consommatrices et en particulier l’information spécifique sur les produits de protection intime sur les trois points essentiels suivants : la composition de ces produits, les modalités et précautions d’utilisation et les risques sanitaires associés à la composition ou l’utilisation de ces produits. Dans ce contexte, la DGCCRF et la DGS souhaitent disposer d’un avis de l’Anses sur le projet de décret relatif à l’information sur les produits de protection intime , en particulier sur les modalités et précautions d’utilisation mentionnées en annexe de ce projet, telles quenotamment le temps de port maximal recommandé des produits de protection intime à usage interne et la recommandation d’utilisation des produits de protection intime à usage externe la nuit

Note d’appui scientifique et technique de l’Anses relative au projet de décret relatif à l’information sur les produits de protection intime

Citation suggérée : Anses. (2022). Note d’appui scientifique et technique de l'Anses relative au projet de décret relatif à l’information sur les produits de protection intime. (saisine 2022-SA-0106). Maisons-Alfort : Anses, 22 p.En 2019, l’Anses a publié un avis et un rapport sur la sécurité des protections intimes (Anses, 2019). Cette expertise n’a pas mis en évidence de préoccupation sanitaire liée aux substances chimiques présentes dans ces produits. Cependant, le principal risque documenté lié au portde protections intimes internes (tampon, coupe menstruelle) est le syndrome de choc toxique menstruel (SCT) qui, bien que rare, peut entrainer de graves conséquences sur la santé des femmes qui en sont victimes. Les protections intimes externes (serviettes, protège-slips) n’ontjamais été impliquées dans le SCT menstruel. Depuis cette expertise, des actions ont été mises en œuvre par le Gouvernement afin d’inciterles industriels à mettre en place des autocontrôles périodiques des produits et à améliorer leur processus d’approvisionnement et de fabrication de façon à supprimer ou limiter autant que possible la présence de substances chimiques préoccupantes (HAP, dioxines, furanes, phtalates, pesticides notamment). D’autre part, des contrôles périodiques ont été diligentés sur ces produits par la DGS et la DGCCRF dont les derniers résultats d’enquête sur les nouveaux produits de protection intime (serviettes réutilisables ou culottes menstruelles, tampons à usage unique dits « biologiques » ou réutilisables) ont été publiés en mars 2022. La DGCCRF et la DGS ont rédigé conjointement un projet de décret qui vise à renforcer laprotection et l’information des consommatrices et en particulier l’information spécifique sur les produits de protection intime sur les trois points essentiels suivants : la composition de ces produits, les modalités et précautions d’utilisation et les risques sanitaires associés à la composition ou l’utilisation de ces produits. Dans ce contexte, la DGCCRF et la DGS souhaitent disposer d’un avis de l’Anses sur le projet de décret relatif à l’information sur les produits de protection intime , en particulier sur les modalités et précautions d’utilisation mentionnées en annexe de ce projet, telles quenotamment le temps de port maximal recommandé des produits de protection intime à usage interne et la recommandation d’utilisation des produits de protection intime à usage externe la nuit