The Biochemistry of Plant Sterols

Sterolic biomarkers in marine phytoplankton. I. Free and conjugated sterols ofPavlova lutheri(Haptophyta)

“…The total sterol content of 0-15% of dry weight (Table 1) is in the range of results published for plants and other algae (Nes, 1977). In macroalgae, percentages of dry weight vary from 0"03 for Cladophora rupestris to 0"3 for Fucus vesiculosus (Dup6ron et al, 1983).…”

“…In contrast, intermediates of biosynthetic pathways, epibrassicaterol and 24-methylenecholesterol, are present in small amounts in all forms with the exception of GS. A7 cholestenol, thus far considered a biosynthetic intermediate (Nes, 1977), may have a more specific role because of its occurrence exclusively in GS. With regard to the dihydroxysterols (pavlovols), it is interesting to note that, as in P. gyrans, they are concentrated in the polar fraction (Gladu et al, 1991) and, more precisely, as shown here, as steryl glycosides exclusively.…”

Characterization of Lipid Rafts from Medicago truncatula Root Plasma Membranes: A Proteomic Study Reveals the Presence of a Raft-Associated Redox System

“…D 5 -Sterols (stigmasterol, sitosterol, and isofucosterol) were also detected. Whereas most higher plants contain D 5 -sterols as major sterols, predominance of D 7 -sterols appears to be restricted to a few plant families including the Theaceae, Cucurbitaceae, and Sapotaceae (Nes, 1977). The sterol composition of M. truncatula roots is similar to that of Medicago sativa shoots (Huang and Grunwald, 1988), but differs significantly from that reported for M. truncatula cell suspension cultures (Suzuki et al, 2002).…”

Evolutionarily conserved Δ25(27)-olefin ergosterol biosynthesis pathway in the alga Chlamydomonas reinhardtii

“…Based on spectra of reference materials ( 31,37,38 ), the sterols from the different cell types possessed one or more functional groups of a ⌬ 22 E double bond, Relevant ions for ergosterol appeared at m /-396, 381, 378, and 363 amu and for 7-dehydroporiferasterol at m / z 410, 395, 392, and 377 amu ( Fig. 3 ) (27) -olefi n intermediate, analogous to 24 ␤ -methyl sterols in other green algae (Chlorella and Trebouxia; 22,40 ) and in the nonphotosynthetic, Chlorellalike alga Prototheca ( 13,41 ). Our results rule out the ⌬ 24 (28) olefi n pathway used in fungal ergosterol biosynthesis ( 39,42 ) because, in the fungal pathway, the methyl groups in 24-methyl and 24-ethyl sterols incorporate two and four deuterium atoms, respectively ( Fig.…”

“…analyses, and isotopic labeling studies ( 15,19 ), point toward the existence of a mevalonate-independent pathway to sterols in Chlorophyta, including green algae, and diatoms (44)(45)(46). Alternatively, other algal groups associated with the Streptophyta operate the acetate-mevalonate pathway to sterols, such as the Klebsormidales Spirogyra aligned with land plants ( 45 ) in addition to all fungal and animal systems ( 1,40 ). Our work confi rms that the chemistry of the C24-alkylation-reduction reactions provides an independent set of characters.…”