Eel sperm cryopreservation: An overview

Abstract

The eels are teleost fishes from the order Anguilliformes that includes several species with high commercial value. Due to the high interest for aquaculture production of some eel species and for the need to restore eel species that are endangered, several research groups have directed their research toward developing protocols to cryopreserve the spermatozoa of Japanese eel (Anguilla japonica) and European eel (Anguilla anguilla).In this review, we provide an overview on the different protocols that have been developed so far. The first developed protocols used DMSO as cryoprotectant in both species with good success, obtaining sperm motilities of over 45% in Japanese eel and over 35% in European eel. Moreover, sperm cryopreserved using DMSO was successfully used in fertilization trials, although with low fertilization rates. However, recent studies show that DMSO produce epigenetic changes in eel sperm and therefore, the last developed protocols used methanol as cryoprotectant instead. Cryopreservation protocols using methanol as cryoprotectant, showed improved motility values in both Japanese and European eel. In addition, the latest protocols have been adapted to cryopreserve larger volumes of sperm of up to 5 mL, which is useful for larger scale fertilization trials.The present study introduces the state of the art and future perspectives of the eel sperm cryopreservation to be applied in aquaculture and biological conservation programs.

Cryopreservation Studies in Aquaculture from Past to Present: Scientific Techniques and Quality Controls for Commercial Applications

“…Sperm freezing in eels was first tried in Japanese eel in the 2000s [61]. And after this study, a lot of studies have been done on freezing the sperm of eels, including the sperm of European eels, with the development of protocols being prioritized [62].…”

A short review of discovery and development of fish sperm cryopreservation

“…Extenders are generally designed to match the physical and chemical composition of sperm cells (Agarwal, 2011). Common extender used for fish cryopreservation are Ringer's solution (Li et al, 1994;Pillai et al, 1994;Muchlisin et al, 2004;Pan et al, 2008;Muchlisin et al, 2018;Muchlisin et al, 2020), NaCl (Gwo, 1993;Glogowski et al, 2002;Maria et al, 2006), artificial seminal plasma (ASP) (Herranz et al, 2019;Le et al, 2011;Lim and Le, 2013), marine fish ringer (MFR) (Kiriyakit et al, 2011;Widyaningsih et al, 2019;Afni et al, 2019), coconut water (Viveiros et al, 2010;Silva et al, 2012;Muchlisin et al, 2010;Muchlisin et al, 2015;Abinawanto and Putri, 2017).…”

Advances in Cryopreservatives: Exploring Safer Alternatives

“…It is important to know that dehydration will occur if there is higher osmotic pressure outside the cell. Some dehydration is beneficial for cryopreservation, as it reduces the formation of penetrating CPAs reproductive cells or even embryos of different species: avian sperm, 13 Nile tilapia sperm, 28 eel sperm, 29 Glossogobius giuris spermatozoa, 30 Mytilus embryos, 31 human oocytes, 32,33 human embryonic stem cells, 34 ovarian carcinoma cell lines, 35 and neuron-like cells 36 sulfoxides and amides DMSO, acetamide, dimethylformamide, or dimethylacetamide penetrating CPAs synthesized from dimethyl sulfide sperm cryopreservation methods, 39−53 Trichogaster fasciata embryos, 40,54 and human ovarian carcinoma cell lines (SKOV-3, OVCAR-8) 35 DMSO: limit ice nucleation and promote viability after thawing 37,38 amino acids and amines proline, glutamine, betaine, L-carnitine, or tricine neutral amino acids (β-alanine, γ-aminobutyric acid (GABA), and ε-aminocaproic acid (ε-Ahx)) proline: great osmoregulatory capacity, as well as a strong capacity to prevent water crystallization 55 proline: sperm samples, oocytes or in human endothelial cells 58 (sRBCs); 56 GLC-82, LTEP-a-2, 3T3 and smooth muscle cells; 55 Jurkat cells; 26 and human spermatozoa 59 proline + trealose: preservation of cell morphology 56 glutamine: spermatozoa, including humans, 60 boar, 61 ram 62 and rooster, 63 and epididymal sperm in Egyptian spiny mice 20 glutamine: improves motility and protects membrane integrity against damage caused by the freeze−thaw process 20 neutral amino acid-based (β-alanine, γ-aminobutyric acid (GABA), and ε-aminocaproic acid (ε-Ahx)) CPA solutions: cryopreserve GLC-82 cells and SMCs 64 betaine: hydrophilic molecule that has a high capacity for hydration through the ionic solvation effect with its charged groups (inhibitor of ice formation) intracellular ice. However, if the dehydration is very high, then irreversible damage to the cell can occur because of cryopreservation.…”