Animal Reproduction Science 131 (2012) 211–218 Contents lists available at SciVerse ScienceDirect Animal Reproduction Science journal homepage: www.elsevier.com/locate/anireprosci Sea bass sperm freezability is influenced by motility variables and membrane lipid composition but not by membrane integrity and lipid peroxidation S. Martínez-Páramo a,∗ , P. Diogo a , M.T. Dinis a , M.P. Herráez b , C. Sarasquete c , E. Cabrita c a CCMAR-Center for Marine Science, University of Algarve, Campus Gambelas, 8005-139 Faro, Portugal b Department of Molecular Biology, Area of Cell Biology, University of León, 24071 León, Spain c ICMAN-Institute of Marine Science of Andalusia, Spanish National Research Council, Av. Republica Saharaui 2, 11510 Puerto Real, Cádiz, Spain a r t i c l e i n f o Article history: Received 19 January 2012 Received in revised form 9 March 2012 Accepted 14 March 2012 Available online 29 March 2012 Keywords: European sea bass Sperm cryopreservation Sperm cryo-resistance Sperm freezability Lipid peroxidation Sperm motility a b s t r a c t Cryopreserved sperm quality depends on the characteristics of fresh sperm. Thus, it is necessary to establish a group of variables to predict the cryopreservation potential of the fresh samples with the aim of optimizing resources. Motility, viability, lipid peroxida- tion and lipid profile of European sea bass (Dicentrarchus labrax) sperm were determined before and after cryopreservation to establish which variables more accurately predict the sperm cryopreservation potential in this species. Cryopreservation compromised sperm quality, expressed as a reduction of motility (46.5 ± 2.0% to 35.3 ± 2.5%; P < 0.01) and viability (91.3 ± 0.7% to 69.9 ± 1.6%; P < 0.01), and produced an increase in lipid peroxi- dation (2.4 ± 0.4 to 4.0 ± 0.4 moles MDA/mill spz; P < 0.01). Also, significant changes were observed in the lipid composition before and after freezing, resulting in a reduction in the cholesterol/phospholipids ratio (1.4 ± 0.1 to 1.1 ± 0.0; P < 0.01), phosphatidylcholine (47.7 ± 0.8% to 44.2 ± 0.8%; P < 0.01) and oleic acid (8.7 ± 0.2% to 8.3 ± 0.2%; P < 0.05) in cryopreserved sperm, as well as an increase in lysophosphatidylcholine (4.4 ± 0.3% to 4.8 ± 0.3%; P < 0.01) and C24:1n9 fatty acid (0.5 ± 0.1% to 0.6 ± 0.1%; P < 0.05). Motility, veloc- ity, cholesterol/phospholipids ratio, monounsaturated fatty acids and the n3/n6 ratio were positively correlated (P < 0.05) before and after freezing, whereas, viability and lipid peroxi- dation were not correlated. Motility and the cholesterol/phospholipids (CHO/PL) ratio were negatively correlated (P < 0.05) with each other and the CHO/PL ratio was positively corre- lated (P < 0.05) with lipid peroxidation. Therefore, the results demonstrated that motility and plasma membrane lipid composition (CHO/PL) were the most desirable variables deter- mined in fresh samples to predict cryo-resistance in European sea bass sperm, taking into account the effect of both on cryopreserved sperm quality. © 2012 Elsevier B.V. All rights reserved. 1. Introduction In general, cryopreservation has been widely used for reproductive practices, germplasm conservation and genetic improvement of resources in several species of ∗ Corresponding author. Tel.: +351 289 800 900x7374; fax: +351 289 800 069. E-mail address: sparamo@ualg.pt (S. Martínez-Páramo). mammals (Watson and Fuller, 2001). However, despite its application to preserve the genetic profile of threatened species (He et al., 2011; Martínez-Páramo et al., 2009) or strains with biotechnological interest (Robles et al., 2009), cryopreserved sperm is scarcely used for routine fertilization practices. Factors such as reduced motility and fertilization ability, embryo development failure or reduced offspring survival and quality (Cabrita et al., 2010; Pérez-Cerezales et al., 2010, 2011) limit the use of cryop- reserved fish sperm. However, this may be counteracted 0378-4320/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.anireprosci.2012.03.008