E.Ian Mercer

Inhibition of ergosterol biosynthesis in saccharomyces cerevisiae and Ustilago maydis by tridemorph, fenpropimorph and fenpropidin

Abstract The structurally related fungicides, tridemorph, fenpropimorph and fenpropidin have been shown to inhibit the sterol Δ 14 -reductase and Δ 8 →Δ 7 -isomerase during ergosterol biosynthesis in Saccharomyces cerevisiae and Ustilago maydis . However, although the three fungicides are able to inhibit both enzymes, tridemorph inhibits the Δ 8 -Δ 7 -isomerase better than the Δ 14 -reductase whilst the reverse is true for fenpropidin and to a lesser extent for fenpropimorph.

Inhibition of sterol Δ8 → Δ7-isomerase and Δ14-reductase by fenpropimorph tridemorph and fenpropidin in cell-free enzyme systems from Saccharomyces cerevisiae

Abstract Enzymatic assay systems have been used to directly demonstrate the inhibition of sterol Δ8 → Δ7-isomerase and Δ14-reductase during ergosterol biosynthesis in Saccharomyces cerevisiae by the structurally related fungicides, fenpropimorph, tridemorph and fenpropidin. Whilst tridemorph is shown to be a strong inhibitor of the Δ8 → Δ7-isomerase, fenpropimorph and fenpropidin are found to be very potent inhibitors of both enzymic reactions. The dual site of action exhibited by these two fungicides predicts a lower risk of resistance development against this group of compounds.

The identification of 24-methylene-24,25-dihydrolanosterol and other possible ergosterol precursors in Phycomyces blakesleeanus and Agaricus campestris

Abstract The following sterols have been isolated from the fungi, Phycomyces blakesleeanus and Agaricus campestris : ergosterol, lanosterol, 24-methylene-24,25-dihydrolanosterol and episterol. 4,4-Dimethyl-5α-ergosta-8.24(28)-dien-3β-ol and 4α-methyl-5α-ergosta-8,24(28)-dien-3β-ol have been tentatively identified. Evidence for the incorporation of label from l -methionine-[methyl- 14 C] into some of these sterols in P. blakesleeanus has been obtained. The significance of these sterols in ergosterol biosynthesis is discussed.

Sterol esters of Phycomyces blakesleeanus

Abstract The sterol esters of Phycomyces blakesleeanus are based on ergosterol, episterol, ergosta-7-en-3β-ol, ergosta-7,22-dien-3β-ol, cholesterol, lan

Sterols, sterol esters and fatty acids of Botrydium granulatum, Tribonema aequale and Monodus subterraneus

Abstract The composition of the sterols, sterol esters and fatty acids has been determined in 8-, 11- and 14-day cultures of three members of the Xanthophyceae, Botrydium granulatum, Tribonema aequale and Monodus subterraneus. The main sterols, whether esterified or unesterified, were cholesterol and clionasterol, whose proportions do not vary with age of culture. Much smaller quantities of cycloartenol and 24-methylenecycloartanol were also found in all three algae. The C16 fatty acids are the most common fatty acids in all three algae with C16:1 being particularly abundant. B. granulatum and T. aequale, however, differ from M. subterraneus in having polyunsaturated C16 fatty acids and a smaller proportion of C20:5.

Chlorosulpholipids in algae

Abstract The docosane series of chlorosulpholipids has been detected by GC-MS in two members of the Xanthophyceae, Botrydium granulatum and Monodus subterraneus , two members of the Chlorophyceae, Elakatothrix viridis and Zygnema sp. and a member of the Cyanophyceae, Nostoc sp. E.

Variation in the levels and composition of the sterols and sterol esters of Phycomyces blakesleeanus with age of culture

Abstract Comparisons of the fatty acid composition of the sterol esters, triglycerides and phospholipids and the sterol composition of the esterified and uneste

Biosynthesis of sterol esters in Phycomyces blakesleeanus

Abstract A cell-free enzyme preparation of P. blakesleeanus has been shown to possess phosphatidylcholine: sterol acyltransferase, sterol ester hydrolase an

Effect of some sterol-biosynthesis-inhibiting fungicides on the biosynthesis of polyisoprenoid compounds in winter wheat seedlings

Abstract The effect of five sterol-biosynthesis-inhibiting (SBI) fungicides, triadimefon, triarimol, diclobutrazol, tridemorph and fenpropimorph on the germination, growth and chloroplast pigment and sterol content of winter wheat seedlings has been studied. Triadimefon, triarimol and diclobutrazol at 250 μM depressed germination and growth, caused the accumulation of 14α-methylsterols but had no effect on the formation of chlorophylls or carotenoids. Tridemorph and fenpropimorph at 250 μM had no effect on germination or the formation of chlorophylls and carotenoids but depressed growth and caused the accumulation of 9β,19-cyclopropylsterols.

Occurrence of a 3′-phosphoadenosine 5′-Phosphosulphate synthesizing system In two Ochromonas species

Abstract The presence of an enzyme capable of incorporating 35SO42− into 3′-phosphoadenosine 5′-phosphosulphate has been demonstrated,in Ochromonas danica and O. malhamensis. This system probably includes the enzymes ATP:sulphate adenyltransferase. E.C. 2.7.7.4 and ATP:adenylsulphate 3′-phosphotransferase, E.C. 2.7.1.25.