Aquaculture Canada and WAS North America 2022

August 15 - 18, 2022

St Johns, Newfoundland, Canada


Christopher C. Parrish

 Department of Ocean Sciences,

 Memorial University of Newfoundland,

St. John’s, Newfoundland, A1C 5S7 Canada


Of the four principal classes of biomolecules, i.e. carbohydrates, proteins, lipids, and nucleic acids, lipids stand out among the various metabolites in terms of the sheer number of distinct chemical entities. The diversity in lipid structures leads to a diversity in chemical and physical properties and then to a wide variety of biological functions ranging from energy storage to the formation of biological membranes, to cell signaling, inflammation, and immunity. 

Lipids differ from the other major groups of biomolecules in that they are not polymers of relatively small numbers of different building blocks. They exist in highly interconnected metabolic pathways leading to various combinations of fatty acyl chains, backbone structures, and polar headgroups. The variety of polar headgroups gives rise to different phospholipids which make up most of the total lipids in membranes. These membranes form barriers for cells and organelles and act as a solvent within which membrane proteins fold and function. Each specialised membrane has a unique composition.

Until recently, the comprehensive analysis of lipids generally involved separation into simpler categories, according to their chemical nature. Lipids would be quantified as bulk species and/or as individual components. Advances in chromatography and mass spectrometry permitting quantitation of lipid molecular species is greatly propelling our ability to study metabolic pathways and networks.

Lipidomics is the complete analysis of lipid molecular species, including their quantitation, in order to study metabolic pathways and networks. The large number and structural diversity of natural lipids and their modifications make lipidomic analyses challenging. It has been estimated that there may be as many as 200,000 individual lipid structures.

The method of choice for sensitive detection and quantitation of lipid molecular species is mass spectrometry, especially with electrospray ionization, either by direct infusion (shotgun lipidomics) or coupled with liquid chromatography. A specialization of mass spectrometry, isotope-ratio mass spectrometry, is used to measure the relative abundance of isotopes in a sample. Compound-specific stable isotope analysis can be used to determine the extent of long-chain polyunsaturated fatty acid synthesis or the uptake and movement of organic nutrients from farm outputs to the surrounding ecosystem.