Effects of soya lecithin on the growth, gonad development, transcription of genes related with fatty acid synthesis and inflammation between sexes of sea urchin Strongylocentrotus intermedius (A. Agassiz, 1864)

A 28-day feeding experiment was performed to investigate the effects of soya lecithin (SL) addition on the growth, gonad development, fatty acid composition, transcription of genes related with fatty acid synthesis and inflammation between sexes of sea urchin Strongylocentrotus intermedius (A. Agassiz, 1864). Three experimental diets were prepared with increasing levels of SL (0%, 1.6%, and 4%). Each diet was randomly assigned to eight male and eight female sea urchins individually cultured in floating cages. The results showed that SL addition significantly decreased the weight gain rate of male sea urchins but had no significant effects on that of female individuals. The gametogenesis of male S. intermedius was markedly accelerated by SL addition at a moderate level (1.6%), reflected by more spermatozoa and fewer nutritive phagocytes in the testis. By comparison, the gametogenesis of female individuals was only slightly promoted by 1.6% and 4% SL addition, with no oocytes observed in the ovary. The contents of arachidonic acid (ARA) in the digestive tract and gonads, and eicosapentaenoic acid (EPA) in the gonads of male and female S. intermedius were increased by SL addition at a moderate level, although their contents were still lower than the initial values. Similarly, the transcription of most fatty acid synthesis-related genes was significantly increased by 1.6% SL addition in both sexes of S. intermedius. The transcription of almost all inflammation-related genes increased with the increase of SL addition in both male and female S. intermedius. Notably, male S. intermedius showed higher ARA contents and transcription of most fatty acid synthesis and inflammation related genes than their female counterparts, especially in the SL1.6 and/or SL4 groups. In summary, SL addition showed no beneficial or negative effects on growth performance but markedly promoted gonad development and ARA and EPA accumulation in S. intermedius, especially at a moderate level (1.6%). Males showed faster gametogenesis than females possibly due to relatively higher ARA synthesis and cyclooxygenase-2 mediated eicosanoid production. The retarded growth and gametogenesis of male S. intermedius fed diets with the addition of 4% SL could be due to excessive inflammation. These results could be helpful for understanding the dosage-dependent and sex-related physiological effects of SL on growth and gonad development of S. intermedius.