The Effects of Cryopreservation on the Cell Ultrastructure in Aquatic Organisms

Ultrastructural examination of cryodamage in Paracentrotus lividus eggs during cryopreservation

This study examinates the challenges of cryopreserving sea urchin (Paracentrotus lividus) eggs, a task hindered by factors like low membrane permeability and high sensitivity to cryoprotective agents (CPAs). While successful cryopreservation has been achieved for some marine invertebrates, eggs remain problematic due to their unique characteristics. The study explores the impact of various CPAs and cryopreservation techniques on sea urchin eggs, employing scanning and transmission electron microscopy to analyze cellular damage. The findings reveal that exposure to low CPA concentrations (0.5 M) did not induce significant damage to eggs. However, high concentrations (3 M) proved highly detrimental. Every cryopreservation approach investigated in this study resulted in irreversible damage to the sea urchin eggs, rendering them nonviable for future use. The research sheds light on the importance of understanding the structural alterations induced by CPAs and cryopreservation methods. This knowledge is essential for refining cryopreservation methods, potentially paving the way for successful preservation of these challenging cells.

Wild coral oocytes are more amenable to low temperature preservation than cultured counterparts

Few studies have examined the biochemical differences between cultured and wild coral after undergoing low-temperature preservation. The present study aimed to explore the differences in the biochemical characteristics of cultured and wild coral cells and oocytes (Echinopora gemmacea and Oxypora lacera) in cryopreservation conditions. Wild and cultured coral cells were extracted and subjected to freezing experiments involving multiple types and concentrations of cryoprotectant, and the oocytes from the cultured and wild corals were subjected to chilling experiments. Cultured and wild coral cells exhibited no significant differences in viability or cell density after cryopreservation, whereas the oocytes from the cultured corals E. gemmacea and O. lacera exhibited lower chilling tolerance compared with their wild counterparts. Significant differences were observed between the oocytes from the cultured and wild corals after low-temperature preservation, particularly in their metabolic activity and vital status, which could be possibly attributed to food consumption and environmental factors. The study provides a foundation for research promoting the technological development of artificial coral propagation and cryopreservation.