Browsing by Author "Matias, Domitilia"
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- Comparative study on cellular and molecular responses in oyster sperm revealed different susceptibilities to cryopreservationPublication . F RIESCO, MARTA; Félix, Francisca; Matias, Domitilia; Joaquim, Sandra; Suquet, Marc; Cabrita, ElsaThe Portuguese (Crassostrea angulata) and Pacific oyster (Crassostrea gigas), both from the genus Crassostrea, are two important species for production and conservation. Although they have common characteristics, different susceptibilities to rearing conditions have been described in these species. Overall, in the case of C. angulata, only a few remaining populations are present in the south of Portugal and Spain. The preservation of genetic material from improved stocks or from the original population is crucial in oysters to prevent the potential impacts of epidemic diseases and natural disasters. Sperm cryopreservation in oysters has progressed in recent years. However many issues, such as protocol standardization, are still unsolved for the application of research results. In the present study a sperm cryopreservation protocol, previously published in C. angulata by our group, were analyzed in terms of cellular and molecular damage, in an effort to determine the most sensible parameters to standardize the cryopreservation protocols for both species. Different approaches in the analysis of sperm quality were performed for the first time in this genus to detect different susceptibilities between the two valuable species. Our results revealed that our previously published protocol containing 10% DMSO as cryoprotectant is more suitable comparing to 10% EG in both species. In addition, an integrative analysis was performed in both oyster species comparing all cellular parameters and C. gigas showed a higher susceptibility to cryopreservation using this optimized protocol. Moreover, higher susceptibility to transcript degradation was detected in C. gigas using this optimized cryopreservation protocol. This study highlights the importance of using different techniques and exhaustive analyses for selecting the most suitable cryopreservation protocol and its standardization, thus ensuring the total safety of the technique.
- First study in cryopreserved Crassostrea angulata spermPublication . F RIESCO, MARTA; Félix, Francisca; Matias, Domitilia; Joaquim, Sandra; Suquet, Marc; Cabrita, ElsaSperm cryopreservation is a widely employed technique that promotes alternative techniques to contribute to broodstock management or restoration programs for species of commercial interest, endangered species or species with an interesting genotype. The preservation of genetic material from improved stocks or from the original population is extremely important for the oyster aquaculture industry to prevent the potential impacts of epidemic diseases and natural disasters. The Portuguese oyster, Crassostrea angulata, was the most important species commercialized by the shellfish industry. However, inadequate management of this industry and pathology occurrences resulted in a significant decrease in natural populations. For this reason, in this work a successful sperm cryopreservation protocol for this important species has been developed for the first time. Different internal cryoprotectants (DMSO, ethylene glycol, polyethylene glycol and methanol) at several concentrations (5, 10, 20%), containers (straws vs cryovials) and freezing rates (slow and fast rates) were tested. Cryoprotectant toxicity tests corroborated that this assay did not take into account the following steps of cryopreservation protocol as sperm agglutination. A fast freezing rate of cells diluted in 10% DMSO and the use of straws as containers were the best cryopreservation conditions for Portuguese oyster sperm. Finally, fertilization assays confirmed the efficiency of the cryopreservation protocol in oyster sperm. These results demonstrated that different susceptibilities have been detected concerning sperm cryopreservation depending on oyster species or genetic material composition. (C) 2016 Elsevier Inc. All rights reserved.
- New species in aquaculture: are the striped venus clam Chamelea gallina (Linnaeus, 1758) and the surf clam Spisula solida (Linnaeus 1758) potential candidates for diversification in shellfish aquaculture?Publication . Joaquim, Sandra; Matias, Domitilia; Matias, Ana Margarete; Gonçalves, Rui; Chicharo, Luis; Gaspar, MiguelThe surf Spisula solida and the striped venus Chamelea gallina clams support important fisheries in Europe. These fisheries have been affected by inter-annual fluctuations in stock abundance and recruitment failures. Aquaculture could contribute to address these problems through the production of larvae or juveniles for stock-enhancement programmes. In the present study, the prerequisites to produce these species in hatchery were established. Of the different methods used to obtain gametes (thermal stimulation, scarification and flow through), C. gallina spawned in the flow through only. By its turn, the best method for obtaining gametes for S. solida was stripping. Higher survivals of D-larvae were found at 15 and 17 degrees C. The greatest larval survival and growth rates were obtained from larvae fed Isochrysis aff. galbana (T-iso). First C. gallina and S. solida pediveliger larvae were found at day 8 and day 26 respectively. The presence of metamorphosed larvae found even in the unfed treatment for C. gallina and for S. solida is an advantage for aquaculture production. After metamorphosis, the S. solida juveniles' survival was quite low, whereas there was no mortality for C. gallina juveniles reared without substrate regardless the diet provided. Juveniles fed the binary diet (Chaetoceros calcitrans - C. cal + T.iso) and the monodiet T-iso showed relatively higher growth in shell length and weight than C. cal. The hatchery production of these two species was possible, however the results of this study showed that C. gallina can be more attractive for aquaculture than S. solida.
- Rebuilding viable spawner patches of the overfished Spisula solida (Mollusca : Bivalvia): a preliminary contribution to fishery sustainabilityPublication . Joaquim, Sandra; Gaspar, Miguel; Matias, Domitilia; Ben-Hamadou, Radhouan; Arnold, William S.Populations of commercially important bivalves along the coast of Portugal are depleted as a consequence of natural and anthropogenic causes. A pilot experiment was designed to determine the feasibility of transplanting individuals from natural clam beds to a closed fishing area in an effort to rebuild relatively high-density patches of Spisula solida. For this purpose, clams were equally partitioned into two groups (undersize and legal clams) and transplanted at a density of 40 clams m(-2) into two areas 50 m(2). Transplanted and control clams were sampled to estimate survival, condition index, biochemical composition, and reproductive condition. Generally, the physiological condition of clams was not affected by the method of transplanting. One year after transplanting, survival was 45%. The increase in local abundance of mature clams should facilitate successful fertilization and increase the residual reproductive value of each clam relative to its pre-transplant value. Transplanting undersize clams may be more advantageous because they are more likely to spawn at least once before harvest. The experiments demonstrate that spawner transplants may strengthen S. solida populations and can be used in stock-enhancement programmes which, in conjunction with effective management measures, can contribute to the sustainability of the S. solida fishery.