Effect
of thermal regime on fatty acid dynamics in male European eels (Anguilla anguilla) during
hormonally-induced spermatogenesis
R.
Baeza, I. Mazzeo, M.C. Vílchez, V. Gallego, D.S. Peñaranda, L. Pérez, J.F.
Asturiano
Abstract
Little
is known about the role of fat and fatty acids in European eel spermatogenesis.
The aim of this work was to study the changes in fat content and to carry out a
quantitative analysis of the fatty acid composition of the muscle, liver and
gonad of European male eels throughout hormonally induced sexual maturation.
The experiment was carried out under three different thermal regimes (two of
them variable: T10 and T15; and one constant: T20) to replicate the changes of
temperature that these fish undergo during their transoceanic reproductive
migration. The European eel reached spermatogenesis earlier in treatment T20,
suggesting that spermatogenesis in this species is closely regulated by water
temperature. Although eels lose body mass due to the period of fasting that
accompanies gonadal growth, no significant changes were found in the fat and
fatty acid content of the muscle during the experimental period.
With
regards to the liver, the levels of palmitic, eicosapentaenoic (EPA) and
docosahexaenoic (DHA) acids increased significantly at the start of the
spermiation process in all the thermal treatments.
In
the testis, EPA, arachidonic acid (ARA) and DHA remained constant during the
maturation process while the levels of the rest of the fatty acids decreased
significantly. The stability of ARA and EPA levels in the testis may have a
physiological significance, whereas the stability of DHA levels may have a
structural one. The results suggest that the advancement of spermiation is
influenced by water temperature and demonstrate the importance of the roles of
EPA, ARA and DHA in European eel reproduction. This study makes it clear that
complementary studies focusing on lipid composition of commercial diets could
improve sperm quality in this species.
