The roles of endolithic fungi in bioerosion and disease in marine ecosystems. II. Potential facultatively parasitic anamorphic ascomycetes can cause disease in corals and molluscs

Anamorphic ascomycetes have been implicated as causative agents of diseases in tissues and skeletons of hard corals, in tissues of soft corals (sea fans) and in tissues and shells of molluscs. Opportunist marine fungal pathogens, such as Aspergillus sydowii, are important components of marine mycoplankton and are ubiquitous in the open oceans, intertidal zones and marine sediments. These fungi can cause infection in or at least can be associated with animals which live in these ecosystems. A. sydowii can produce toxins which inhibit photosynthesis in and the growth of coral zooxanthellae. The prevalence of many documented infections has increased in frequency and severity in recent decades with the changing impacts of physical and chemical factors, such as temperature, acidity and eutrophication. Changes in these factors are thought to cause significant loss of biodiversity in marine ecosystems on a global scale in general, and especially in coral reefs and shallow bays

L’élevage des mollusques

Seminario Interdisciplinar de Acuicultura Marina desarrollado del 18 al 21 de septiembre de 1973, Vigo, España.-- 4 pagesL'élevage des mollusques a été pendant longtemps limité en Europe aux huîtres et aux moules et, accessoirement, aux palourdes (Venerupis decussata), aux clams (Mercenaria mercenaria) et aux littorines (Littorina littorea). Depuis quelques années, on cherche à l'étendre à d'autres coquillages, ormeau (Haliotis sp.), coquille St Jacques (P. Maximus ou P. yessoensis), etc. [...] C. cigas, Crassostrea angulataPeer reviewe

MPF interactors during M-phase and M-phase exit in Xenopus laevis eggs

International audienc

Evaluation of the effects of a semi-automated vitrification performed before or after in vitro maturation (IVM) on the kinetic of oocyte maturation and chromosome segregation.

International audienceStudy question:What are the optimal vitrification method (semi-automated vs. manual) and oocyte stage for in vitro-matured oocyte cryopreservation using meiosis kinetics and chromosome segregation as readouts?Summary answer:The semi-automated vitrification method does not impact oocyte nuclear maturation quality compared with the manual method. Immature oocyte cryopreservation should be performed after IVM.What is known already ?Fertility preservation using oocyte vitrification should be performed before oncological treatments. The reference protocol consists in collecting mature oocytes after ovarian stimulation. Nevertheless, ovarian stimulation sometimes yields immature oocytes or cannot be performed (e.g., emergency oncological treatment). An IVM step is therefore required but it is not clearly demonstrated whether IVM should be performed before or after vitrification. Oocyte vitrification is usually performed with manual methods. A semi-automated vitrification device (Gavi®, Genea Biomedx) showing high performances for embryo was recently released. To our knowledge, no study has analysed its efficiency on oocyte vitrification. Study design, size, duration:200 immature oocytes collected from ICSI cycles from January 2020 will be used. Oocytes will be divided in five groups (40 oocytes/group): freshly matured oocytes (group 1 control), oocytes vitrified after IVM by a manual technique (group 2a) or by Gavi® (group 2b) and oocytes vitrified prior IVM (groups 3a and 3b). We assess oocyte nuclear maturation quality by evaluating IVM kinetics by time-lapse (Geri®) and the accuracy of homologous chromosomes segregation by CGH array. Participants/materials, setting, methods:Since January 2020, 124 out of 200 immature oocytes have been included for this study. These oocytes provide from women under 37 years old without ovulatory disorder after signing an informed consent. The kinetics of meiotic resumption (germinal vesicle breakdown (GVBD) and polar body extrusion (PBE) timings), is determined by time-lapse technology (Geri®, Genea Biomedx). The accuracy of the homologous chromosome segregation during the first meiotic division will be assessed by CGH-Array. Main results and the role of chance:The clinico-biological characteristics (age, BMI, smoking and total FSH dose) are comparable between the five groups (p>0.05). No significant difference in post-thawing oocyte survival rate is observed between the two vitrification methods (semi-automated 58% vs. manual 64%). A significant difference in the overall oocyte survival rate is observed according to the stage of vitrification with a significantly higher survival rate if oocytes are vitrified at the mature stage (93% (2a+2b) vs. 61% (3a+3b), p =0.02). The IVM rate is significantly higher if oocytes are matured freshly (86% in group 1 (fresh IVM, n= 7) and 93% in group 2a+2b (IVM before vitrification, n= 27)) compared to post vitrification (71% in group 3a+3b, n= 28), p=0.03. The vitrification technique does not seem to impact IVM rate since it reached 64% (group 3a, n=11) and 76% (group 3b, n=16) (p=0.4). GVBD and PBE timings are not significantly different between the 5 groups, suggesting that neither the oocyte stage of vitrification nor the vitrification technique affects maturation kinetics. Similarly, our preliminary results of polar bodies and oocytes chromosomal profiles assessed by CGH-Array demonstrate a similar rate of aneuploidy (monosomy or trisomy) between the groups. Limitations, reasons for caution:Our preliminary results of CGH array should be confirmed with the analysis of a larger number of IVM oocytes. Wider implications of the findings:Vitrification of immature oocytes should be performed by semi-automated or manual methods after IVM. Tour knowledge, this is the first study comparing the efficiency of both semi-automated and manual vitrification methods on immature and in vitro-matured oocytes.Trial registration number: NCT0368093

Sustainable large‐scale production of European flat oyster ( Ostrea edulis ) seed for ecological restoration and aquaculture: a review

The conservation and active restoration of European flat oyster (Ostrea edulis) populations are a major focus of ecological restoration efforts to take advantage of the wide‐ranging ecosystem functions and services this species provides. Accordingly, additional and new demands for seed oysters have arisen. In commercial aquaculture (mariculture), the production of O. edulis is still largely based on natural seed collection. Considering the specific requirements, related to ecological restoration, such as the absence of pathogens and the preservation of high genetic diversity, the current supply is insufficient. Despite the development of breeding and controlled reproduction techniques for this species since the late 1930s, seed production today is mainly based on empirical concepts. Several of the issues that producers still face are already subjects of research; many others are still unanswered or even unaddressed. This review provides a summary of all available knowledge and technologies of O. edulis seed production. Furthermore, it provides a detailed reflection on implications for restoration, future challenges, open questions and it identifies relevant research topics for sustainable seed supply. The study covers the following aspects on (i) biology of the species, (ii) stressors – including pathogens and pollutants, (iii) genetics, (iv) history of production technologies, (v) seed production in polls, (vi) seed production in ponds and (vii) seed production in hatcheries. Future research needs on sex determinism, gametogenesis, cryopreservation, nutrition, selective breeding, pathogens and disease, and the development of reliable protocols for production are highlighted