Effect of Sperm Cryopreservation on the European Eel Sperm Viability and Spermatozoa Morphology

Abstract

The main objective of the present work was to study the effect of cryopreservation of European eel sperm both on the sperm viability and the spermatozoa head morphology. Spermatozoa morphology was evaluated with computer-assisted morphology analysis after collection in fresh samples, after adding the freezing medium containing dimethyl sulfoxide as cryoprotectant and, finally, after the cryopreservation process and thawing. Cell viability was assessed, in both fresh and thawed samples, by Hoechst 33258 staining. Computer-assisted sperm analysis (CASA) was used to determine the percentage of motile cells and to measure motility parameters in sperm samples. A significant decrease of head perimeter (12.56%) and area (17.90%) was detected from spermatozoa in fresh to thawed samples, indicating that cells do not recover the original size after the cryopreservation process. CASA was used to measure the percentage of motile cells (51.9%) and spermatozoa motility parameters such as curvilinear, straight line and angular path velocities, as well as beating cross frequency. This technique was employed in the fresh sperm samples but proteins present at the freezing medium (L-alpha-phosphatidylcholine) made impossible to use this last technique in thawed samples. When sperm viability was assessed by Hoechst staining, a significant decrease of approximately 15% (73.10 vs 58.26%) of alive spermatozoa was registered from fresh to thawed samples. The percentage of motile cells measured by CASA in fresh samples (51.9%) was lower than the percentage of alive cells determined by Hoechst stainning, suggesting the existence of different batches of spermatozoa in different stages of development, even during the eight to tenth weeks of treatment, when the highest sperm quality was found.

Effect of the probiotic Lactobacillus rhamnosus on the expression of genes involved in European eel spermatogenesis

“…Former studies have shown that hCG could induce spermatogenesis and sperm maturation in the European eel [4,[19][20][21][22][23]. This treatment promotes a plasma increase of androgen (11-ketotestosterone ) by the Leydig cells [13,15,16,24,25].…”

Criopreservacion de espermatozoides del lenguado Paralichthys adspersus

“…Relación entre valores porcentuales de motilidad espermática y fecundación. motilidad espermática post congelación-descongelación de 75,1 ± 1,7% (Marco-Jiménez et al, 2006;Asturiano et al, 2007), o en Sparus aurata donde se obtuvieron motilidades de 70,0 ± 4,7% usando una solución crioprotectora formada por DMSO y albúmina sérica de bovino (BSA) (Cabrita et al, 2005). Estos resultados sugieren que la inclusión de vitelo de huevo de gallina (VHG) dentro de la solución crioprotectora que se utilizó en el proceso de criopreservación de los espermatozoides de P. adspersus, generaría una mayor protección durante el proceso de congelación que sería proporcionada por las lipoproteínas presentes en el VHG y estar previniendo de daños en la membrana plasmática (Scott & Baynes, 1980;Suquet et al, 2000) o incrementando la resistencia de la membrana celular ante el estrés osmótico durante el congelamientodescongelamiento de los espermatozoides (Cabrita et al, 1998).…”

Sperm physiology and quality in two marine teleosts: Anguilla anguilla & Takifugu niphobles

“…These sperm biomarkers have so far been documented in scientific papers, and several traits of the fish/sperm itself, such as osmolality, pH and chemical composition of the seminal plasma Asturiano et al, 2007;Sadiqul and Akhter, 2011) have been linked to the ability of sperm to fertilize the ova. Some of these parameters can be scored relatively easily and are commonly used because no expensive equipment is needed and they are quick and easy to assess.…”

“…These sperm biomarkers have so far been documented in scientific papers, and several traits of the fish/sperm itself, such as osmolality, pH and chemical composition of the seminal plasma (Asturiano et al, 2005;Ciereszko, 2008); enzymatic activity (Burness et al, 2005); ATP concentration (Suquet el al., 2010); spermatocrit and sperm density (Harald et al, 2001;Sørensen et al, 2013); sperm motility (Ottesen et al, 2009); or sperm morphology and ultrastructure Asturiano et al, 2007;Sadiqul and Akhter, 2011) have been linked to the ability of sperm to fertilize the ova. Some of these parameters can be scored relatively easily and are commonly used because no expensive equipment is needed and they are quick and easy to assess.…”

“…The evaluation of sperm motility and other kinetic parameters like curvilinear, straight line, and average path velocities, and morphology, is an essential tool in the examination of sperm quality in many fish species (Liu et al, 2007;Marco-Jiménez et al, 2008;Gallego el at., 2012), including the European eel (Gallego el at., 2012;Marco-Jiménez et al, 2006;Asturiano et al, 2007). Despite the fact that for many years optic microscopes have conventionally been used to carry out analyses and evaluations, it is considered subjective method and great variations have been reported (Coetzee et al, 1999).…”