Thermal acclimation and dietary lipids alter the composition, but not fluidity, of trout sperm plasma membrane

Abstract

The effect of a long-term adaptation of rainbow trout to 8 and 18 degrees C combined with a corn oil- or a fish oil-supplemented diet on the characteristics of the spermatozoan plasma membrane was investigated. The experiment lasted up to 22 mon during which spermatozoa were collected from the mature males. Spermatozoan plasma membranes were isolated by nitrogen cavitation, and the cholesterol content, phospholipid composition and fatty acid pattern were investigated. Membrane viscosity was assessed on whole cells by electron spin resonance using spin-labeled phospholipids. Neither diet nor rearing temperature influenced the cholesterol content of the plasma membrane nor the phospholipid class distribution. The rearing temperature of the broodstock only slightly affected the phospholipid fatty acids. A minor decrease in 18:0 and increase in monounsaturated fatty acids was observed for the cold-adapted fish. These modifications were not sufficient to affect membrane fluidity, and we conclude that trout spermatozoa do not display any homeoviscous adaptations in these conditions. On the contrary, the dietary fatty acid intake greatly modified the fatty acid profile of plasma membrane phospholipids. The fish oil-fed trout displayed a much higher n-3/n-6 fatty acid ratio than did the corn oil-fed ones, but the 22:6n-3 levels remained unchanged. Modifications in plasma membrane composition by the diet were obtained although neither of the two diets was deficient in essential fatty acids. The enrichment in n-3 fatty acids, however, did not affect plasma membrane fluidity which was unchanged by the diets.

Roles of lipids and fatty acids through the spermatogenesis of European eel (Anguilla anguilla)

“…Labbé et al (1995) also observed the maintenance of a specific level of some PUFAs in sperm membranes of trout. In our opinion, supplying an adequate diet is vital for the animal, as this will allow making the metabolic effort required to obtain the essential PUFA proportion needed in the sperm.…”

“…The conservation of ARA and EPA levels may have a physiological significance, whereas the constant levels of DHA may have a structural one. In fish, high proportions of DHA have been found in sperm (Bell et al, 1996;Labbé et al, 1993Labbé et al, , 1995Pérez et al, 2000Pérez et al, , 2007Pustowka et al, 2000) indicating it has an important structural function. DHA maximizes transport of electrons in the mitochondria leading to increased energy output (Valentine and Valentine, 2004).…”

“…Studies of goldfish (Wade et al, 1994), rainbow trout (Labbé et al, 1993(Labbé et al, , 1995Pustowka et al, 2000;Vassallo-Agius et al, 2001) and European sea bass Bell et al, 1996) have shown the relationship between the fatty acid content of the broodstock diet and the fatty acid composition of the sperm and suggest that consequently, fertilization could be affected. The preliminary results of the fatty acid composition of European eel testis during sexual maturation have demonstrated that the use of diets with appropriate fatty acid profiles might improve sperm quantity and quality (Butts and Baeza et al, unpublished results; Chapter IV).…”

“…However, nutritional experiments often focus on female broodstock and egg quality, ignoring the effects of diet on sperm and male reproductive performance. Studies of goldfish (Carassius auratus; Wade et al, 1994), rainbow trout (Oncorhynchus mykiss; Labbé et al, 1993Labbé et al, , 1995Pustowka et al, 2000;Vassallo-Agius et al, 2001) and European sea bass (Dicentrarchus labrax; Asturiano et al, 1999;Bell et al, 1996) have demonstrated the relationship between the fatty acid content of the broodstock diet and the sperm fatty acid composition, and have suggested that fertilization could be affected as a consequence. Asturiano et al (2001) showed that the diet of the European sea bass male affected the survival of the embryos and larvae, thus indicating a long-term effect of dietmediated sperm quality.…”

“…It is clear that broodstock nutritional requirements have to be met in order to achieve reproductive performance, and several studies indicate that the composition of dietary lipids affects male reproductive performance in different teleosts, including the European sea bass (Dicentrarchus labrax; (Bell et al, 1996;Asturiano et al, 2001), Eurasian perch (Perca fluviatilis; (Henrotte et al, 2010)), rainbow trout (Oncorhynchus mykiss; (Labbé et al, 1995;Pustowka et al, 2000)), Indian major carp (Catla catla; (Nandi et al, 2007)) and African catfish (Clarias gariepinus; (Nyina-Wamwiza et al, 2012))…”