Handling, Reproducing and Cryopreserving Five European Sea Urchins (Echinodermata, Klein, 1778) for Biodiversity Conservation Purposes

Abstract

In this work, five local sea urchin species found in European waters were studied. Four were regular species: Sphaerechinus granularis, Psammechinus miliaris, Echinus esculentus (Linnaeus, 1758) and the edible sea urchin Paracentrotus lividus; and one was an irregular species, Echinocardium cordatum. These five species of sea urchins have been studied regarding their fertility, toxicity of cryoprotecting agents, cryopreservation of different cell types and chilling injury. The baseline fertility is similar in P. lividus, P. miliaris and S. granularis. Nonetheless, the sperm:egg ratio, contact time and development of the fertilization envelope would need to be studied further on a case-by-case basis. Sperm can be maintained inactively in the gonad (4 °C), and oocytes also maintain quality in sea water (4 °C), even after 72 h. Sperm was cryopreserved for four species with some post-thaw intra specific variability, and embryo cryopreservation was only possible for S. granularis. Overall, this study provided a wider vision of the biology and reproduction of these species that will help us develop tools for their biodiversity conservation through cryopreservation.

Ultrastructural examination of cryodamage in Paracentrotus lividus eggs during cryopreservation

“…3 D–F, 4 D–F, 5 D–F, 6 D–F). These results are consistent with the LOEC (Lowest Observed Effect Concentration) values calculated by Paredes and Bellas 17 and Paredes et al 40 for DMSO, EG and PG.…”

“…Results have shown that exposing the eggs to low concentrations (0.5 M) of DMSO, EG and PG did not cause damage to the cells (Figs. 3 , 4 , 5 , 6 A–C) which is in agreement with prior data of CPA toxicity 17 , 40 . In the case of eggs, the NOEC (No Observed Effect Concentration) values calculated support the results obtained in this study, since after exposing those cells to low concentrations of CPA, the ultrastructure was similar to controls.…”

“…All methods were carried out in accordance with relevant guidelines and regulations of animal handling and care at the Universidade de Vigo. Animals handled in this study are out of scope of the regulations ECC/566/2015, nonetheless animal handling was done to the best standard and following guidelines from Paredes and Costas 65 and Paredes et al 40 . ARRIVE guidelines in experimental design to ensure reliability of research were followed.…”

Cold Storage and Cryopreservation Methods For Spermatozoa of the sea urchinLytechinus pictus

“…The history of cryopreservation of sea urchin sperm began in 1973 (9), and at present, sperm of about 15 species have been cryopreserved as recently reviewed (11,26-28,31). Cryopreservation of sperm of all animals involves dilution of concentrated semen into an extender solution and then mixing this cell suspension with a cryoprotectant such as dimethyl sulfoxide (DMSO).…”

The Importance of Developing and Standardizing Gamete, Embryo and Larvae Handling in Aquatic Animals

“…In all cases, protocols need to be established, shared and standardized within the scientific community to successfully obtain gametes from different mollusks, as well as sea urchins, which also present with external fertilization. Sea urchins are model organisms and, therefore, some species of sea urchins, such as Strongylocentrotus purpuratus or Paracentrotus lividus, are quite well studied and have many protocols in place; however, this is not the case for other sea urchins [6], as it has been shown in many cases that protocols would have to be adapted to particular species. Important knowledge about reproduction is not often well-known or standardized, such as contact time, the egg:sperm ratio, optimum parameters for embryo incubation and expected outcome after larval rearing, but is key information for marine invertebrates [2,6].…”