Browsing by Author "Anjos, Catarina Miranda Castilho dos"
Now showing 1 - 1 of 1
Results Per Page
Sort Options
- Establishment of a genetic resource bank for restocking management in Portuguese oyster (Crassostrea angulata) and striped venus clam (Chamelea gallina)Publication . Anjos, Catarina Miranda Castilho dos; Cabrita, Elsa; Matias, DomitíliaBivalves are essential for fisheries, aquaculture, and ecosystems, serving as nutrient-rich resources for human consumption. Despite their significance, many bivalve resources, including Crassostrea angulata (Portuguese oyster) and Chamelea gallina (striped venus clam) in Europe, evidence signs of depletion due to environmental change, anthropogenic impact, and overexploitation, requiring rehabilitation measures. One possible strategy involves establishing a genetic resource bank via cryopreservation. However, cryopreservation presents challenges, requiring optimization of freezing and thawing conditions, particularly the cryoprotectant solution, and understanding cryodamage. The present thesis aims to explore and establish conditions to store and preserve the genetic resources of C. angulata and C. gallina populations. Chapter 1 provides contextual background, on the current situation of bivalve production and the importance of these resources, with special attention on the endangered and valuable species for aquaculture/fisheries, C. angulata and C. gallina. The chapter addresses the fundamental principles of cryobiology and current knowledge on bivalve cryopreservation methodologies for sperm and larvae. This chapter discusses the value of cryodamage assessment tools, emphasizing “omics” molecular tools for high-potential analysis. Chapters 2 and 3 aim to optimize and develop new cryopreservation protocols for the target species. Chapter 2 investigates the effect of the cryoprotectant supplementation with sugars (trehalose and sucrose) on the post-thaw sperm quality of C. angulata. Several methodologies not commonly used in bivalve cryopreservation works were employed, including the determination of reactive oxygen species levels, acrosome integrity and the activity of antioxidant enzymes (superoxide dismutase - SOD, glutathione reductase - GR and glutathione peroxidase - GPX). Sugars supplementation, especially trehalose reduced lipid peroxidation and ROS levels having a positive effect in plasma membrane and acrosome integrity. Chapter 3 evaluates the larval quality of C. angulata and C. gallina exposed and cryopreserved with cryoprotectant solutions that differ in the permeant agent (dimethyl sulfoxide - DMSO and ethylene glycol - EG). The work aimed to understand the effects of cryoprotectant exposure and, cryopreservation on malformations, movement, and enzymatic activity compared with non-exposed larvae. The methodologies for cryopreserving D-larvae of both species were established for the first time. Chapter 4 investigates C. angulata D-larvae cryodamage during cryoprotectant exposure and cryopreservation, using RNA sequencing. This molecular approach was essential for providing evidence that the freezing process was the critical step rather exposure. Furthermore, identified 11 genes as relevant biomarkers of freezability for D-larvae quality assessment. This thesis presents strategies for cryopreserving the genetic material of C. angulata and C. gallina and for cryodamage evaluation.