Subpopulation pattern of eel spermatozoa is affected by post-activation time, hormonal treatment and the thermal regimen

Abstract

CSIRO PublishingGallego Albiach, V.; Vilchez Olivencia, MC.; Peñaranda, D.; Pérez Igualada, LM.; Herraez, MP.; Asturiano Nemesio, JF.; Martinez-Pastor, F. (2015). The subpopulation pattern of eel sperm is affected by post-activation time, hormonal treatment and thermal regime. Reproduction, Fertility and Development. 27(3):529-543. doi:10.1071/RD13198. Natural stocks of eels (genus Anguilla) have suffered a dramatic reduction in the last 60 years, and 16 aquaculture is based in the capture of huge quantities of juveniles. It is necessary closing the life cycle in 17 captivity to lift the pressure on wild populations. We have aimed at the evaluation of sperm 18 subpopulations (cluster analysis of computer-assisted sperm analysis -CASA-data) in European eel 19 (Anguilla anguilla), assessing the effects of acquisition time (30, 60 and 90 s post-activation), thermal 20 regimes (variable: T10 and T15, constant: T20) and hormonal treatments (hCG, hCG rec or PMSG). In all 21 cases, we obtained three subpopulations: low velocity and linearity (S1), high velocity and low linearity 22 (S2) and high velocity and linearity (S3, considered high-quality). Total motility and S1 were affected by 23 acquisition time, thus recommending 30 s. T20 data fitted quadratic models, with the highest motility and 24 S3 between weeks 8 and 12 after the first injection. T10 and T15 delayed spermiation and the obtention 25 of high-quality sperm (S3), but did not seem to alter the spermiation process (similar subpopulation 26 pattern). Hormonal treatments differed greatly both on the onset of spermiation (PMSG delaying it) and 27 on the dynamics of the subpopulation pattern. Motility and S3 yield of the widely used hCG were very 28 variable. However, hCG rec allowed to obtain good motility for most of the study (weeks 7 to 20), and S3 29 yield was overall higher (61.8%±1.3) and more stable along time than the other hormonal treatments 30(averaging 53.0%±1.4). Economically, T20 and hCG rec were more effective, allowing to obtain a higher 31 number of S3 spermatozoa for an extended time. The genus Anguilla contains many species of great commercial importance, but wild stocks have been 35depleted. This has been due to overfishing (both of glass eels and reproductive eels) and other factors 36 such as parasites, global climate change and other human impacts (Feunteun, 2002;Halpin, 2007). To 37 these factors we must add the peculiar life cycle of these species: Adults spawn in the sea (an event not 38 witnessed yet); leptocephali larvae drift until they reach coastal waters; they metamorphose into glass eels 39 and move inland while they develop into elver and yellow elver stages; after that, they mature to silver 40 eels (the whole growth process could take years to decades), which are capable to recognize its way to the 41 spawning areas, where they fully mature, spawn once and die (Ginneken and Maes, 2005). The 42 complexity of this cycle has contributed to the difficulty of replicating it in captivity. Therefore, although 43 an increasing prop...

Effect of frame rate capture frequency on sperm kinematic parameters and subpopulation structure definition in boars, analysed with aCASA‐Mot system

“…Previously, the whole population of spermatozoa in an ejaculate has been considered; as it was described by a normal distribution model, spermatozoa were considered as equivalent, with the same chances of being “selected” for fertilization. Nevertheless, by considering the quantitative data obtained from CASA systems, different authors have proposed that the actual distribution of sperm cells is not uniform, not normally distributed but structured in well‐defined subpopulations, (Amann & Hammerstedt, ; Caldeira et al., ; Gallego et al., ; Hirai et al., ; Soler et al., ; Thurston, Watson, Mileham, & Holt, ; Valverde et al., ; Vásquez et al., ; Yániz et al., , ). Even today, in the boar, a relationship between these subpopulations and the fertilizing capacity of the ejaculates has been established (Abaigar et al., ; Holt et al., ; Vyt et al., ).…”

“…Another aspect is that the correct determination of sperm tracks results in a fundamental shift in the determination of motility and morphology subpopulation structure. The fact that an ejaculate is constituted of different subpopulations of spermatozoa has been well established in a great variety of species (boar (Abaigar, Holt, Harrison, & del Barrio, ; Flores et al., ; Holt, Holt, & Moore, ; Soler et al., ), bull (Valverde et al., ; Yániz et al., ), donkey (Flores et al., ), eel (Gallego et al., ), fox (Soler et al., , ), gazelle (Abaigar et al., ), goat (Vázquez et al., ), ram (Luna et al., ), stallion (Ortega‐Ferrusola et al., ), human (Vásquez, Soler, Camps, Valverde, & García‐Molina, ; Yániz et al., ), salmon (Caldeira et al., )), but most of these studies were not designed for considering the effect of the FR.…”

Motility of sea urchin Paracentrotus lividus spermatozoa in the post-activation phase

“…Among these, velocity parameters are the most widely used in aquatic species (Liu et al., ). In the last few years, it has been demonstrated that grouping spermatozoa in subpopulations on the basis of their velocity makes it possible to identify changes occurring in the semen with reference to the coexistence of different subpopulations with distinct motility characteristics within the same sample (Beirão, Cabrita, Pérez‐Cerezales, Martinez‐Pánaramo & Herráez, ; Gallego et al., ). Indeed, in the sea urchin A. crassispina , velocity parameters showed significant reduction after exposure to cadmium (Au et al., ), while in the sea bream S. aurata , cryopreservation proved to affect different sperm subpopulations in different ways (Beirão et al., ), while the relative size of the RAP sperm subpopulation was more strongly impaired by toxicants than the TM population (Fabbrocini et al., ).…”

Technologies used in the study of sperm function in cryopreserved fish spermatozoa

“…Once characterized, subpopulations can be related to treatments, male differences, sperm physiology and most importantly, sperm fertility (Martínez‐Pastor, Cabrita, Soares, Anel & Dinis et al . ; Gallego, Vílchez, Peñaranda, Pérez, Herráez, Asturiano & Martínez‐Pastor ).…”