Seasonal variations in the profile of main phospholipids in Mytilus galloprovincialis mussels: A study by hydrophilic interaction liquid chromatography–electrospray ionization Fourier transform mass spectrometry

Abstract

A systematic characterization of phosphatidylcholines and phosphatidylethanolamines in mussels of sp Mytilus galloprovincialis was performed by high-efficiency hydrophilic interaction liquid chromatography combined with electrospray ionization and Fourier transform mass spectrometry (FTMS), based on a quadrupole-Orbitrap hybrid spectrometer. The FTMS/MS experiments under high collisional energy dissociation conditions, complemented by low-energy collisionally induced dissociation MS n (n = 2,3) experiments, performed in a linear ion trap mass spectrometer, were exploited for structural elucidation purposes. The described approach led to an unprecedented characterization of the mussel phospholipidome, with 185 phosphatidylcholines and 131 phosphatidylethanolamines species recognized, distributed among diacylic, plasmanylic, and plasmenylic forms. This was the starting point for the evaluation of the effects of season (in particular, of sea temperature) on the profile of those phospholipids. To this aim, a set of mussel samples retrieved from commercial sources in different periods of the year was considered. Principal component analysis revealed a clear separation between samples collected in periods characterized by cold, intermediate, or warm sea temperatures, respectively. In particular, an enrichment in phospholipids containing unsaturated side chains was observed in mussels collected from cold seawaters (winter-early spring), thus confirming the general model previously elaborated to explain the adaptation of marine invertebrates, including some bivalve molluscs, to low temperatures. On the other hand, relevant levels of plasma(e)nylic and acylic phospholipids bearing either saturated or non-methylene-interrupted side chains were found in mussels collected in warm seawaters (typical of summer and early autumn, at Italian latitudes). This finding opened interesting perspectives towards the development of strategies able to prevent global warming-related mussel losses in aquacultural plants.

Lipidomics analysis of juveniles’ blue mussels (Mytilus edulis L. 1758), a key economic and ecological species

“…However, working at a lipid molecular species level by untargeted lipidomics showed changes in the composition of polar lipids of the spat, offering the most complete overview of the spat lipidome. PC and PE are the main polar lipid components in bivalves [62,64,65,67,88,100] principally observed in the OUT samples (Fig 5B), possibly as a result of seasonality, as an increase of plasmalogens on mussels between winter/spring and summer conditions was found by Facchini, Losito [62]. When spat were fed I. galbana, PC(38:6) was the most abundant PC, as this might have incorporated a DHA molecule in the sn-2 position.…”

“…searching the lipid dataset versus LIPID MAPS (www.lipidmaps.org), HMDB (www.hmdb. ca), Metlin (www.metlin.scripps.edu) and an "in house" bivalve lipid database built from recent bivalve lipidomics studies [60][61][62][63][64][65][66][67][68][69]. Contaminants were manually removed from the peak intensity table (PIT) generated from this process.…”

Direct analysis in real time coupled to high resolution mass spectrometry as a rapid tool to assess salmon (Salmo salar) freshness

“…First, as shown in Table , only one FA bearing an odd number of carbon atoms along its side chain (17:1) was detected, thus confirming the minor role played by this kind of FAs in animal lipid extracts. Actually, as recently emphasized in our studies dealing with mussel lipids, odd‐numbered acyl chains are present, embedded into free FAs or major lipids (phospholipids [PL]), in the case of mollusks, because the latter often use bacteria or algae, much richer in lipids with odd‐numbered side chains, as a source of nutrition.…”

Lipidomics analysis of juveniles’ blue mussels (Mytilus edulisL. 1758), a key economic and ecological species

“…Working at single lipid species level allowed to capture changes in the composition of polar lipids of the spat, which were not observed from lipid class analysis due to the different separation employed in the two techniques. PC and PE are the main polar lipid components in bivalves [62, 64, 65, 67, 87, 99]. Bivalves have well-conserved PC structures, with a SAFA (16:0 and minor 18:0) in sn-1 position and an unsaturated PUFA (EPA or DHA) on sn-2 [99].…”