51
tional, and ring-forming biochemical transformations; modification with sugar residues; and other functional groups of different biosynthetic origin (Fahy et al. 2011).
The International Lipid Classification and the Nomenclature Committee, together
with the Lipid Metabolites and Pathways Strategy (LIPID MAPS) Consortium,
defined eight categories of lipids and divided them into classes and subclasses (Fahy
et al. 2005, 2009, 2011) by their chemically functional backbones and biochemical
principles in (1) fatty acyls, (2) glycerolipids, (3) glycerophospholipids (also known
as phospholipids), (4) saccharolipids (also known as galactolipids), (5) sphingolipids, (6) sterol lipids, (7) prenol lipids, and (8) polyketides. The entire collection of
chemically distinct lipid species in a cell is referred to as a lipidome (Gross and Han
2011). According to different estimates, an eukaryotic lipidome contains 9000–
100,000 individual lipid molecular species (van Meer 2005; Han and Jiang 2009).
Moreover, the estimated number of individual molecular species varies from cell to
cell due to the intrinsic programmed genetic information, status of the cellular activation, metabolic signaling, and nutritional history (Han et al. 2012). Such large
number and diversity of lipid species complicate their separation and identification
thereby making the lipid analysis a challenge to accomplish. However, the advent of
omic sciences has been a stimulus to determine the lipid molecular profile in biological systems, paving the way for “lipidomics.” The term lipidomics was first used
by Kishimoto et al. in 2001 (Kishimoto et al. 2001) and later defined by Han and
Gross in 2003 (Han and Gross 2003). Currently, it is defined as the study of full
complement of lipid molecules (lipidome) on the systems level together with their
interacting factors including expression of proteins involved in lipid metabolism
and function and gene regulation. Lipidomics enables to understand the role that
lipids play in biological systems such as how lipids influence membrane architecture, the modulation of transcription and translation, and answers to environmental
changes due to physiological processes (Rolim et al. 2015). This field has undergone
rapid progress, mainly because of technology-driven transformation in instrumentation, most notably in mass spectrometry and its ancillary techniques (such as liquid
chromatography and ionization sources) that have enabled quantitative lipid analyses with an unprecedented level of sensitivity and precision (Brügger 2014). Recent
studies in lipidomics have largely focused on the identification of novel lipid classes
and molecular species, development of quantitative methods for lipid analysis at
attomole to femtomole levels per mg of protein, tissue mapping of altered lipid
distribution present in different organs or in response to external cues, and bioinformatic approaches for the automated high-throughput processing and molecular
modeling with lipidomic data (Wang et al. 2016). Now, the researchers have realized that metabolism of lipid molecular species or between individual lipid classes
is interwoven and the metabolism of the entire lipidome should be investigated in a
systems biology approach to better understand the functions of lipids in biological
systems (Dennis 2009).
Seaweeds are benthic marine macroalgae comprising a diverse group of fascinating multicellular photosynthetic forms growing mostly attached to rocks in coastal
waters. They are harvested and commercially utilized for food, feed, phycocolloids,
4 Seaweed Lipidomics in the Era of ‘Omics’ Biology: A Contemporary Perspective
tional, and ring-forming biochemical transformations; modification with sugar residues; and other functional groups of different biosynthetic origin (Fahy et al. 2011).
The International Lipid Classification and the Nomenclature Committee, together
with the Lipid Metabolites and Pathways Strategy (LIPID MAPS) Consortium,
defined eight categories of lipids and divided them into classes and subclasses (Fahy
et al. 2005, 2009, 2011) by their chemically functional backbones and biochemical
principles in (1) fatty acyls, (2) glycerolipids, (3) glycerophospholipids (also known
as phospholipids), (4) saccharolipids (also known as galactolipids), (5) sphingolipids, (6) sterol lipids, (7) prenol lipids, and (8) polyketides. The entire collection of
chemically distinct lipid species in a cell is referred to as a lipidome (Gross and Han
2011). According to different estimates, an eukaryotic lipidome contains 9000–
100,000 individual lipid molecular species (van Meer 2005; Han and Jiang 2009).
Moreover, the estimated number of individual molecular species varies from cell to
cell due to the intrinsic programmed genetic information, status of the cellular activation, metabolic signaling, and nutritional history (Han et al. 2012). Such large
number and diversity of lipid species complicate their separation and identification
thereby making the lipid analysis a challenge to accomplish. However, the advent of
omic sciences has been a stimulus to determine the lipid molecular profile in biological systems, paving the way for “lipidomics.” The term lipidomics was first used
by Kishimoto et al. in 2001 (Kishimoto et al. 2001) and later defined by Han and
Gross in 2003 (Han and Gross 2003). Currently, it is defined as the study of full
complement of lipid molecules (lipidome) on the systems level together with their
interacting factors including expression of proteins involved in lipid metabolism
and function and gene regulation. Lipidomics enables to understand the role that
lipids play in biological systems such as how lipids influence membrane architecture, the modulation of transcription and translation, and answers to environmental
changes due to physiological processes (Rolim et al. 2015). This field has undergone
rapid progress, mainly because of technology-driven transformation in instrumentation, most notably in mass spectrometry and its ancillary techniques (such as liquid
chromatography and ionization sources) that have enabled quantitative lipid analyses with an unprecedented level of sensitivity and precision (Brügger 2014). Recent
studies in lipidomics have largely focused on the identification of novel lipid classes
and molecular species, development of quantitative methods for lipid analysis at
attomole to femtomole levels per mg of protein, tissue mapping of altered lipid
distribution present in different organs or in response to external cues, and bioinformatic approaches for the automated high-throughput processing and molecular
modeling with lipidomic data (Wang et al. 2016). Now, the researchers have realized that metabolism of lipid molecular species or between individual lipid classes
is interwoven and the metabolism of the entire lipidome should be investigated in a
systems biology approach to better understand the functions of lipids in biological
systems (Dennis 2009).
Seaweeds are benthic marine macroalgae comprising a diverse group of fascinating multicellular photosynthetic forms growing mostly attached to rocks in coastal
waters. They are harvested and commercially utilized for food, feed, phycocolloids,
4 Seaweed Lipidomics in the Era of ‘Omics’ Biology: A Contemporary Perspective