LIPID-COMPOSITION AND OXIDATION STATUS IN BRAIN OF WILD-CAUGHT SIZE-CLASS DISTRIBUTED PARAPENAEUS-LONGIROSTRIS (LUCAS, 1846)

The objectives of the study were to characterize the lipid composition , the oxidation status (represented by the levels of malondialdehyde ( MDA)), vitamin E content and the fluorescence intensity of lipid-solub le fluorescent products (LSFP) in neural tissues from males and female s of wild-caught size-class distributed of the pink shrimp Parapenaeus longirostris (Lucas, 1846), trawled in the south Atlantic coast of Sp ain. Moreover, the mechanisms that might produce the deposition of age -pigments in relation to the physiological age of this species in its natural environment were also investigated. Three different size class es were defined for each sex, resulting in lower sizes for males than for females. The proportion of polar lipids predominated over that of neutral lipids and no significant differences were observed either bet ween different size-classes within sex or between different sex but be longing to the same size-class. The major polar lipid classes were pho sphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidyls erine (PS) and no significant differences were observed between differ ent groups. However, the cerebrosides fraction showed a significant up ward trend from class I to III in both males and females. The fatty ac id composition of total lipids, PC, PE and PS in the pink shrimp showe d, in most cases, an increase in monounsaturated fatty acids (particul arly 18:1(n-9) and 24:1(n-9)) and a decrease in polyunsaturated fatty acids (primarily 22:6(n-3)) with increasing size-age. In males, the co ncentration of MDA (nmol g(-1) brain) and fluorescence intensity (% mg (-1) TL) were positively correlated (r = 0.77; P < 0.02) but both were negatively correlated to carapace length in the different sizes (r = -0.88; P < 0.002 and r = -0.81; P < 0.01, respectively). The concentra tion of vitamin E (ng mg(-1) brain) was positively correlated to carap ace length (r = 0.85; P < 0.005) showing a parallel increase of brain membrane lipids and the most potent biological antioxidant vitamin. In females, the concentration of MDA (nmol g(-1) brain), fluorescence in tensity (% mg(-1) TL) and vitamin E (ng mg(-1) brain) were not correla ted to carapace length of the different sizes (under study) and showed no significant differences between the three different size classes. The fluorescence analysis of brain LSFP was not a useful tool to separ ate the population into different size classes. (C) 1998 Elsevier Scie nce Inc. All rights reserved.