Browsing by Author "Matias, Domitília"
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- Assessment of larval quality of two bivalve species, Crassostrea angulata and Chamelea gallina, exposed and cryopreserved with different cryoprotectant solutionsPublication . Anjos, Catarina; Duarte, Daniel; Diogo, Patrícia; Matias, Domitília; Cabrita, ElsaMarine bivalves are valuable resources, however, some shellfish populations are endangered due to factors such as anthropogenic pressure, pathologies or lack of reproduction synchrony. Portuguese oyster (Crassostrea angulata) and striped venus clam (Chamelea gallina) have high socio-economic value and their endangered natural populations require rehabilitation. Cryopreservation is a valuable method for the preservation and management of genetic resources for aquaculture and restocking. Larvae cryopreservation is particularly valuable since diploid organisms are obtained upon thawing. The objective of this work was the establishment of C. angulata and C. gallina D-larvae cryopreservation through the selection of permeant cryoprotectant in the freezing solution, namely ethylene glycol (EG) and dimethyl sulfoxide (Me2SO). Cryoprotectants exposure showed that, in C. angulata, Me2SO promoted significantly higher incidence of abnormalities and enhanced glutathione reductase activity when compared to control (larvae without cryoprotectant exposure) or even to EG treatment. However, for both species, EG significantly reduced D-larvae average path velocity (VAP). In C. angulata post-thaw D-larvae, EG treatment promoted significantly lower motility and velocity when compared to control and Me2SO treatment. Superoxide dismutase (SOD) activity showed a reduction in C. angulata postthaw D-larvae when compared to control, which was compensated by the enhancement of glutathione peroxidase (GPX) activity. In C. gallina post-thaw D-larvae, only motility, velocity and SOD activity were significantly lower than control. Therefore, the best treatment to cryopreserve C. angulata D-larvae was EG while for C. gallina Me2SO produced better results. This work established for the first time D-larvae cryopreservation protocols for C. angulata and C. gallina.
- Bycatch and discard survival rate in a small-scale bivalve dredge fishery along the Algarve coast (southern Portugal)Publication . Anjos, Mariana; Pereira, Fábio; Vasconcelos, Paulo; Joaquim, Sandra; Matias, Domitília; Erzini, Karim; Gaspar, MiguelAlthough the bivalve dredge used on the Algarve coast (southern Portugal) is highly selective for the target species, in some periods of the year the bycatch can exceed the catch of the commercial species. The present study aimed to quantify the bycatch and discards, estimate damage and mortality, and propose management measures to minimize discards and mortality. A total of 15 fishing surveys (60 tows) were performed using two types of dredges (“DDredge” targeting Donax trunculus and “SDredge” targeting Spisula solida and Chamelea gallina). Of the 85257 individuals (392.4 kg) of 52 taxa that were caught, 73.4% belonged to the target species, 22.1% to commercially undersized target species and 4.5% to bycatch species. Bycatch rates were lower for SDredge (13.5% in number and 6.3% in weight) than for DDredge (46.0% in number and 32.9% in weight). Damage and mortality rates were also lower using SDredge (1.3% and 1.0% of the total catches, respectively) than using DDredge (4.0% and 2.8% of the total catches). Survival experiments revealed the diverse vulnerability of the taxa and confirmed the influence of the damage score on the mortality rate. The results gathered in the present study encourage the adoption of a bycatch reduction device to reduce both direct and indirect mortality.
- Calcification, growth and mortality of juvenile clams Ruditapes decussatus under increased pCO(2) and reduced pH: variable responses to ocean acidification at local scales?Publication . Range, Pedro; Chicharo, Alexandra Maria; Ben-Hamadou, Radhouan; Piló, David; Matias, Domitília; Joaquim, Sandra; Oliveira, A. P.; Chícharo, LuísWe investigated the effects of ocean acidification on juvenile clams Ruditapes decussatus (average shell length 10.24 mm) in a controlled CO2 perturbation experiment. The carbonate chemistry of seawater was manipulated by diffusing pure CO2, to attain two reduced pH levels (by −0.4 and −0.7 pH units), which were compared to unmanipulated seawater. After 75 days we found no differences among pH treatments in terms of net calcification, size or weight of the clams. The naturally elevated total alkalinity of local seawater probably contributed to buffer the effects of increased pCO2 and reduced pH. Marine organisms may, therefore, show diverse responses to ocean acidification at local scales, particularly in coastal, estuarine and transitional waters, where the physical–chemical characteristics of seawater are most variable. Mortality was significantly reduced in the acidified treatments. This trend was probably related to the occurrence of spontaneous spawning events in the control and intermediate acidification treatments. Spawning, which was unexpected due to the small size of the clams, was not observed for the pH −0.7 treatment, suggesting that the increased survival under acidified conditions may have been associated with a delay in the reproductive cycle of the clams. Future research about the impacts of ocean acidification on marine biodiversity should be extended to other types of biological and ecological processes, apart from biological calcification.
- Comparative transcriptome analysis reveals molecular damage associated with cryopreservation in Crassostrea angulata D-larvae rather than to cryoprotectant exposurePublication . Anjos, Catarina; Duarte, Daniel Filipe Correia; Fatsini Fernández, Elvira; Matias, Domitília; Cabrita, ElsaThe Portuguese oyster Crassostrea angulata, a bivalve of significant economic and ecological importance, has faced a decline in both production and natural populations due to pathologies, climate change, and anthropogenic factors. To safeguard its genetic diversity and improve reproductive management, cryopreservation emerges as a valuable strategy. However, the cryopreservation methodologies lead to some damage in structures and functions of the cells and tissues that can affect post-thaw quality. Transcriptomics may help to understand the molecular consequences related to cryopreservation steps and therefore to identify different freezability biomarkers. This study investigates the molecular damage induced by cryopreservation in C. angulata D-larvae, focusing on two critical steps: exposure to cryoprotectant solution and the freezing/thawing process. Results Expression analysis revealed 3 differentially expressed genes between larvae exposed to cryoprotectant solution and fresh larvae and 611 differentially expressed genes in cryopreserved larvae against fresh larvae. The most significantly enriched gene ontology terms were "carbohydrate metabolic process", "integral component of membrane" and "chitin binding" for biological processes, cellular components and molecular functions, respectively. Kyoto Encyclopedia of Genes and Genomes enrichment analysis identified the "neuroactive ligand receptor interaction", "endocytosis" and "spliceosome" as the most enriched pathways. RNA sequencing results were validate by quantitative RT-PCR, once both techniques presented the same gene expression tendency and a group of 11 genes were considered important molecular biomarkers to be used in further studies for the evaluation of cryodamage. Conclusions The current work provided valuable insights into the molecular repercussions of cryopreservation on D-larvae of Crassostrea angulata, revealing that the freezing process had a more pronounced impact on larval quality compared to any potential cryoprotectant-induced toxicity. Additionally, was identify 11 genes serving as biomarkers of freezability for D-larvae quality assessment. This research contributes to the development of more effective cryopreservation protocols and detection methods for cryodamage in this species.
- Effect of trehalose and sucrose in post-thaw quality of Crassostrea angulata spermPublication . Anjos, Catarina; Santos, Ana Luísa; Duarte, Daniel; Matias, Domitília; Cabrita, ElsaSperm cryopreservation can be a helpful tool in reproductive management and preservation of biodiversity. However, the freezing methodologies lead to some damage in structure and function of cells that may compromise post-thaw sperm activity. Cryoprotectant supplementation with sugars proved to be a successful strategy to reduce cryodamage in sperm of several species, once allowing to stabilize the plasma membrane constituents. Therefore, this study intends to understand the effects of sugars in the plasma membrane, DNA integrity, and oxidative response during Portuguese oyster sperm cryopreservation. Three cryoprotectants solutions with an initial concentration of 20% dimethyl sulfoxide (DMSO) and 20% DMSO complemented with 0.9 M trehalose or sucrose in artificial seawater were employed. Sperm samples of mature males were individually collected and diluted 1:10 (v/v) in artificial seawater followed by addition of cryoprotectants [1:1 (v/v)]. Thereafter, sperm was loaded into 0.5 ml straws, maintained at 4◦C for 10 min, frozen in a programmable biofreezer at −6 ◦C/min from 0 to −70◦C, and stored in liquid nitrogen. Samples were thawed in a 37◦C bath for 10 s. Several techniques were performed to evaluate post-thaw quality. Sperm motility and DNA integrity were analyzed by using computer-assisted sperm analysis (CASA) software and comet assay. Flow cytometry was employed to determine membrane and acrosome integrity and to detect intracellular reactive oxygen species (ROS) and apoptosis activity. Lipid peroxidation was determined by malondialdehyde (MDA) detection by using spectrophotometry. Sperm antioxidant capacity was evaluated through glutathione peroxidase, glutathione reductase, and superoxide dismutase. Motility was not affected by the extenders containing sugars; these compounds did not reduce the DNA damage. However, both the trehalose and sucrose protected plasma membrane of cells by increasing cell viability and significantly reducing MDA content. The same finding was observed for the ROS, where live cells registered significantly lower levels of ROS in samples cryopreserved with sugars. The activity of antioxidant enzymes was higher in treatments supplemented with sugars, although not significant. In conclusion, the addition of sugars seems to play an important role in protecting the Crassostrea angulata sperm membrane during cryopreservation, showing potential to improve the post-thaw sperm quality and protect the cells from cryoinjuries.
- Effects of sea-water acidification on fertilization and larval development of the oyster Crassostrea gigasPublication . Barros, P.; Sobral, P.; Range, Pedro; Chícharo, Luís; Matias, DomitíliaOceans face a serious change to their natural biogeochemical cycle due to the rapid absorption of CO2 generated by human activities. Ocean acidification is the common term used to describe the decrease of seawater pH caused by the absorption of atmospheric CO2. To evaluate the effects of ocean acidification, we focused on the larval stage of bivalves, which produce a fragile calcareous skeletal structure, very sensitive to changes in seawater chemistry. In this context, we investigated sperm motility, fertilization rate and larval viability (survival, growth and abnormalities) of the Pacific oyster, Crassostrea gigas, a commercially important bivalve, in a controlled CO2 perturbation experiment. The carbonate chemistry of seawater was manipulated by diffusing pure CO2, to attain two reduced pH levels (ΔpH=−0.4 and ΔpH=−0.7) which were compared to unmanipulated seawater. The results show high sensitivity of C. gigas veliger larvae to low values of pH, as reflected by a decrease in survival and growth rates, as well as an increased frequency of prodissoconch abnormalities and protruding mantle. Moreover, results also show that sperm motility, fertilization rate, and hatching success, were negatively influenced by acidification. The exposure to ΔpH=−0.7 had a higher impact on the fertilization and larval viability than ΔpH=−0.4. The results suggest that the reproductive success and the biological mechanisms for calcification may be prematurely interrupted and disturbed when C. gigas veliger larvae are exposed to an acidified environment which may reduce their viability and compromise settlement and future abundances of this species.
- Genetic diversity of two Portuguese populations of the pullet carpet shell Venerupis senegalensis, based on RAPD markers: contribution to a sustainable restocking programPublication . Joaquim, Sandra; Pereira, Jorge C.; Leitão, Alexandra; Matias, Domitília; Chaves, Raquel; Guedes-Pinto, Henrique; Chícharo, Luís; Gaspar, MiguelThe pullet carpet shell Venerupis senegalensis (=V. pullastra) is a commercially important species in Portugal, Spain, France, and Italy. In Portugal, this species was once abundant in the Ria Formosa (southern Portugal)
- Larval hatching and development of the wedge shell (Donax trunculus L.) under increased CO2 in southern PortugalPublication . Pereira, Alexandre Miguel; Range, Pedro; Campoy, Ana; Oliveira, Ana Paula; Joaquim, Sandra; Matias, Domitília; Chícharo, Luís; Gaspar, MiguelNoticeable changes in global temperatures, climate and ocean carbon chemistry are the result of carbon dioxide increase in the atmosphere. This increase has been mitigated by the oceans capacity to absorb one-fourth of the carbon dioxide in the atmosphere, although this CO2 intake affects oceans carbonate chemistry [i.e., ocean acidification-(OA)]. The detrimental effect of OA in the development and shell formation has been studied in several species of bivalves, although no information is available on the wedge shell Donax trunculus, a gastronomically appreciated species and an important economical resource in several southern European countries. We evaluated the effect of pCO(2) increase on hatching and early life stages of D. trunculus, considering two ocean acidification scenarios (Delta pH -0.3 and Delta pH -0.6). Our results showed that elevated pCO(2) caused a delay in hatching into D-larvae and reduced larvae survival. In the extreme scenario (Delta pH -0.6), some trochophore larvae persisted to day 9 of the experiment and more abnormal larvae were produced than in the Delta pH -0.3 and control treatments. At day 5, normal veligers under extreme acidification were smaller than in other treatments, but by day 9, these differences were attenuated and the average size of normal D-larvae varied inversely to the pH gradient. Possible underlying mechanisms for these complex response patterns are discussed, including the existence of phenotypic plasticity or genetic pre-adaptive capacity in this D. trunculus population to cope with future environmental changes.
- Relationships between broodstock condition, oocyte quality, and 24h D-larval survival during the spawning season of the pullet carpet shell Venerupis corrugata (Gmelin, 1791)Publication . Joaquim, Sandra; Matias, Domitília; Matias, Ana Margarete; Gonçalves, Rui; Vera, Cátia; Chícharo, Luís; Gaspar, MiguelVenerupis corrugata is commercially exploited in Europe. Over-fishing and recruitment failure is causing the decline of its populations and stock sustainability. Knowledge of this species reproduction is paramount to establish hatchery production of juveniles for restoring natural beds. This work aimed to find a relationship between broodstock condition, oocyte quality, and viability of 24h D-larvae. Adult specimens were induced to spawn by thermal stimulation. From each female, oocytes were taken for biochemical analyses (proteins, total lipids, and carbohydrates), and the remaining oocytes were fertilized. The 24h D-larval yield was calculated after embryo incubation. Spawning in the hatchery with 'wild' broodstock was possible for a long period, however, subsequent larval viability varied according to oocyte quality. Two distinct periods of spawning were recorded: in January/March, with a higher number of oocytes released, and in June/July with a lower response to the spawning stimulation, however with greater success in 24h D-larval survival. The condition index of broodstock and the total lipids of oocytes released can be used as benchmarks for estimating the success of D veliger larvae.
- Reproductive activity and biochemical composition of the pullet carpet shell Venerupis senegalensis (Gmelin, 1791) (Mollusca: Bivalvia) from Ria de Aveiro (northwestern coast of Portugal)Publication . Joaquim, Sandra; Matias, Domitília; Matias, Ana Margarete; Moura, Paula; Arnold, William S.; Chícharo, Luís; Baptista Gaspar, MiguelThe present study characterizes the reproductive cycle of Venerupis senegalensis (=V. pullastra) from Ria de Aveiro (Portugal) as well as its nutrient storage and exploitation strategy. The reproductive cycle followed a seasonal cycle that correlated negatively with sea surface temperature, and comprised a ripe stage in winter followed by a spawning period that began in late winter and ended in the early summer. This extended spawning may be an advantageous strategy for the species because it ensures a continuous supply of settlers. Gametogenesis began in late summer/early autumn and intensified with the decrease in temperature during autumn. The condition index increased even during the spawning period, which indicates that there is rapid recovery and that reserves are accumulated during late summer and used later in the gametogenic process. Proteins did not contribute significantly to gametogenesis and the glycogen pattern is typical of conservative species, since gametogenesis depends largely on the amount of glycogen stored. The lipid storage and utilization cycle showed that gametogenesis took place in autumn/winter and that energy reserves were accumulated in summer.