Japanese eel (Anguilla japonica Temminck & Schlegel, 1846) propagation using cryopreserved sperm samples

Abstract

Summary The aim of this study was to test the artificial seminal plasma (ASP) as the extender as well as methanol as the cryoprotectant for cryopreservation, and to collect information on the fertilizing capacity of cryopreserved sperm samples. Eggs from Japanese eel, Anguilla japonica, females were control‐fertilized with native sperm diluted with ASP and cryopreserved sperm (ASP as extender [in 1:100 ratio] and 10% methanol in v/v final concentration). No statistical differences (p < .05) were among the measured parameters (hatching, survival after 10 days post‐hatch, malformation rates) between the two groups, thus this cryopreservation method can be used effectively for artificial propagation of the Japanese eel, Anguilla japonica.

Comparison of European eel sperm cryopreservation protocols with standardization as a target

“…Although DMSO is the most used cryoprotectant for fish sperm (Gallego & Asturiano, 2018b;Martínez-Páramo et al, 2017), methanol has also been widely used in freshwater species such as sturgeons, salmonids, tench or Eurasian perch within others (reviewed by Asturiano et al, 2017). Furthermore, it has been recently used in cryopreservation protocols for Japanese eel sperm (Koh et al, 2017;Müller et al, 2017Müller et al, , 2018. As cryoprotectant, methanol has been reported to penetrate more rapidly the cells and being less toxic than DMSO (Horváth et al, 2015).…”

Improvement of techniques for sperm evaluation and cryobanking in European eel.

“…Although DMSO is the most used cryoprotectant for fish sperm (Gallego and Asturiano, 2018a;Martínez-Páramo et al, 2017), methanol has also been widely used in freshwater species such as sturgeons, salmonids, tench or Eurasian perch within others (reviewed by Asturiano et al, 2017). Furthermore, it has been recently used in cryopreservation protocols for Japanese eel sperm (Koh et al, 2017;Müller et al, 2017;. As cryoprotectant, methanol has been reported to penetrate more rapidly the cells and being less toxic than DMSO (Horváth et al, 2015).…”

“…Years later, Müller et al (2017) and Koh et al (2017) developed in parallel new sperm cryopreservation protocols for Japanese eel. Both protocols used methanol as cryoprotectant, which is osmotically inert and do not activate the sperm, and used similar extender solutions, ASP and ASP30 respectively.…”

“…For long time, this was the only published Japanese eel sperm cryopreservation protocol, until Müller et al (2017) published a new cryopreservation protocol in which an artificial seminal plasma (ASP) and methanol were used as extender and cryoprotectant, respectively. The composition of ASP was based on the Ohta et al's study (1997), and was prepared with (in mM) 149.3 NaCl, 15.2 KCl, 1.3 CaCl2, 1.6 MgCl2 and 20 NaHCO3, buffered with 20 mM TAPS-NaOH at pH 8.1, and possess iso-ionic osmolality to the seminal plasma of artificially maturated Japanese eel.…”

“…Moreover, the protocol used 0.5 mL straws and the freezing was conducted in LN vapor for 3 min, 3 cm over the LN surface, before immersion and storage, and the thawing consisted of immersion for 13 s in water at 40 ºC. Although Müller et al (2017) successfully cryopreserved Japanese eel sperm, the embryos hatched using cryopreserved samples showed lower survival and higher malformation rate than those of fresh sperm, indicating that the protocol was still sub-optimal.…”