Chlorophyll c2 monogalactosyldiacylglyceride ester (chl c2-MGDG). A novel marker pigment for Chrysochromulina species (Haptophyta)

Abstract

The pigment composition of the haptophyte Chrysochromulina polylepis (Strain CCMP 286) was analysed by high-performance liquid chromatography (HPLC) using pyridine-containing mobile phases and polymeric C18, or monomeric C8 columns. The polar chlorophyll (chl) c pigment composition included chl c2 and chl c3 as major fractions, and divinyl protochlorophyllide a (DV pchlide or MgDVP) as a minor component. Several non-polar fluorescent peaks sharing a common chl c-type absorption spectrum were also detected. The main component of these peaks was isolated and characterised by chromatographic behaviour, UV-visible (UV-VIS) and fluorescence spec- troscopy. Although spectral properties were similar to a high molecular weight non-polar chl c (1313 Da) recently characterised from Emiliania huxleyi, both chlorophylls showed different chro- matographic behaviour. Fast atom bombardment-mass spectrometry (FAB-MS) analysis showed a high mass molecular ion (m/z 1265), and a fragmentation pattern compatible with a molecular struc- ture consisting of a chl c2 pigment linked by an ester bond to the sugar moiety of a monogalactosyl diacylglyceride (MGDG), which included 2 myristic acid (14:0) residues. To study the distribution pattern of the novel pigment, different strains of C. polylepis and other species of the genus Chrysochromulina were analysed. A similar chl c2 ester was also present in 2 C. polylepis strains (K, B11) and in C. aff. polylepis (PLY 200), as well as in C. acantha, C. camella, C. leadbeateri, C. stro- bilus, C. throndsenii, and Chrysochromulina sp. (CS-410). Three species, C. fragaria, C. hirta (2 strains) and C. kappa, lacked the new chl c, but they contained detectable amounts of other non- polar chl c-like pigments. The feasibility of using chls c and carotenoids as marker pigments to detect Chrysochromulina species in field samples is discussed.