Lipid and fatty acid profiles of gametes and spawned gonads of Arbacia dufresnii (Echinodermata: Echinoidea): sexual differences in the lipids of nutritive phagocytes

Sea urchin gonads contain nutritive phagocytes (NP) that store nutrients such as protein, lipid and carbohydrates for use during the production of gametes. While there is some information on the role of protein, particularly major yolk protein (MYP), during gametogenesis, very little is known about the role of lipids and their component fatty acids. We compared the lipid and FA profile of mature Arbacia dufresnii gonads (intact), with gonads that had been induced to spawn (spawned) and their associated gametes. The total lipid concentration decreased in females from the intact to the spawned gonads, and with a minimum value in the eggs, whilst male intact and spawned gonads had similar lipid concentrations, with significantly lower lipid concentration only in the sperm. Sex was the main factor affecting FA profile in the gonads (intact, spawned) and gametes of A. dufresnii, with differences in both the variety of FA, their total concentration and proportion. Interestingly, sexual differences in FA profile of the gonads are due not only to the presence of mature gametes, but also due to the NP and gametes remaining after spawning. As male and female sea urchins have the same basic gonad wall and NP structure, and the same echinoferrin based system for deposition of the MYP in the NP, our study reveals an unexplored biochemical complexity in the lipids and fatty acids of the NP within sea urchin gonads that has implications for future research.