The
role of lipids in the gonadal development of the clam Ruditapes
decussatus (L.)
M.
Delgado, A. Pérez Camacho, U. Labarta, M.J. Fernández-Reiriz-2004
Aquaculture, 241(1-4): 395-411
Abstract:
The
evolution of phospholipids, free fatty acids, triacylglycerols, sterols and
sterol and wax esters was studied throughout the process of sexual
maturation in Ruditapes decussatus. The clams were fed with three
daily food rations of the microalga Isochrysis galbana: R1: 2.5%, R2:
5.0% and R3: 10.0% (percentages correspond to the organic weight of food
supplied as a proportion of the live weight of clams). The content of total
lipids in the soft tissue increased with sexual maturation. During this
process, the females always accumulated a greater quantity of lipids than
the males, with triacylglycerols, phospholipids and sterol and wax esters
being the components, which mostly determined the sexual differentiation.
The size of the differences between sexes was influenced by the quantity of
food available. Phospholipids constituted the largest lipid fraction in R.
decussatus, representing 57–83% of total lipids. The total quantity of
phospholipids was significantly greater in females than in males, although
the percentage with respect to total lipids was greater in the males, which
showed a low proportion of triacylglycerols. The females always presented a
greater total quantity of triacylglycerols than the males, and a greater
percentage with respect to total lipids (between 9.98% and 18.8%, as a
function of the food ration). The triacylglycerols were absent in the males
throughout sexual maturation, when the food quantity was moderate (R1). When
the food was more abundant (R2 and R3), the sexually mature males
temporarily accumulated triacylglycerols (between 0% and 3.18% of total
lipids), although they disappeared in the final phase of sexual maturation.
The sterol and wax esters followed the same process as the triacylglycerols,
although they were present in lesser proportion (between 4.07% and 6.46% of
total lipids in females and between 0% and 5.75% in males), and also
disappeared in the final phase of sexual maturation.
(Instituto
Español de Oceanografía, Muelle de Ánimas s/n, E-15001, La Coruña,
Spain, e-mail of A. Perez Camacho: alejandro.perez@co.ieo.es)