TY - JOUR
T1 - Differential response of microalgae to the substituted pyridazinone, sandoz 9785, reveal different pathways in the biosynthesis of eicosapentaenoic acid
AU - Khozin, Inna
AU - Cohen, Zvi
N1 - Funding Information:
plants, such as spinach, w3-desaturatiowno uld be tracts were trans-methylatewdith MeOH-AcC1 and mainly chloroplastic\[ 4\].W e suggestt hat a similar analysedbyGC as previouslydescribed\[11\]T.hedata distinctionc an be also made among EPA-producing shownrepresenmt eanvalueswitha rangeof less than algae. Thus, oJ3 desaturatioinn P. cruentumis pre-5% for major(over10% of fatty acids)peaksand15% dominantlcyh loroplasticw, hile in N. oculatao nly the for minor peaks,ofat leasttwoindependensatmples, cytoplasmicw 3-desaturatioisn operativeM. . subter-each analysedin duplicate. raneus,h owever,a pparentlhya s chloroplastic6 o3-de- saturasea ctivity,a s in P cruentuma, nda cytoplasmic Acknowledgements-a-Wree g ratefutl o Ms S. Didi for activity, as in N. oculata and P. tricornutumT. he dedicatedte chnicaal ssistanceto, the Sandozc ompany contenot f 20:4w6i n MGDG in a givena lgamay thus and to Drs J. B. St. John and H. A. Norman for be an indicatoro f the type of biosynthetipca thways generousg ifts of SAN 9785. This researchw as sup-existingi n the alga. Those with a high abundancoef portedi,n part,u nderG rantN o. DPE-5544-G-SS-8017-20:4o)6m ay resembleP . cruentum. 00, U.S.-Israel CooperativeD evelopmenRt esearch ProgramO, ffice of the ScienceA dvisor,U.S. Agency for InternationaDle velopmenatn d by the Manof pro-gram, the Ministry for Science and Culture, Israel. Organisma nd culture conditionsM. . subterraneus ContributionN o. 75 from the Laboratoryfo r Micor-UTEX 151 was obtainedfr om the Universityo f Texas algal BiotechnologyJa, cob BlausteinIn stitutefo r De-CultureC ollectiona ndc ultivateodn BG-1 l mediuma s sert Research. describedin ref. \[16\]P. . cruentums train1380 ld was
PY - 1996/1/1
Y1 - 1996/1/1
N2 - Treating the red alga, Porphyridium cruentum, with the herbicide, SAN 9785, an inhibitor of chloroplastic ω3-desaturation, resulted in a decrease in the proportion of eicosapentaenoic acid (EPA), especially in monogalactosyldiacylglycerols (MGDG). However, when the eustigmatophyte, Monodus subterraneus, was treated with this herbicide, the proportion of EPA in MGDG surprisingly increased from 54 to 81%. Molecular species analysis of MGDG, showed that the prokaryotic molecular species 20:5/16:0 was almost eliminated, while the eukaryotic 20:5/20:5 dominated. These findings indicate that EPA biosynthesis in M. subterraneous is different from that in P. cruentum. We suggest that in M. subterraneus there are at least two pathways involving ω3-desaturase activity which lead to the production of EPA. The chloroplastic pathway, which is inhibited by SAN 9785, and the cytoplasmic pathway, which presumably uses phospholipid-bound fatty acids and is not affected by this inhibition. The product of the latter pathway is exported through the chloroplast membrane resulting in the production of 20:5/20:5 MGDG. We further suggest that, by analogy with higher plants, microalgae can be categorized according to their respective EPA biosynthetic pathways.
AB - Treating the red alga, Porphyridium cruentum, with the herbicide, SAN 9785, an inhibitor of chloroplastic ω3-desaturation, resulted in a decrease in the proportion of eicosapentaenoic acid (EPA), especially in monogalactosyldiacylglycerols (MGDG). However, when the eustigmatophyte, Monodus subterraneus, was treated with this herbicide, the proportion of EPA in MGDG surprisingly increased from 54 to 81%. Molecular species analysis of MGDG, showed that the prokaryotic molecular species 20:5/16:0 was almost eliminated, while the eukaryotic 20:5/20:5 dominated. These findings indicate that EPA biosynthesis in M. subterraneous is different from that in P. cruentum. We suggest that in M. subterraneus there are at least two pathways involving ω3-desaturase activity which lead to the production of EPA. The chloroplastic pathway, which is inhibited by SAN 9785, and the cytoplasmic pathway, which presumably uses phospholipid-bound fatty acids and is not affected by this inhibition. The product of the latter pathway is exported through the chloroplast membrane resulting in the production of 20:5/20:5 MGDG. We further suggest that, by analogy with higher plants, microalgae can be categorized according to their respective EPA biosynthetic pathways.
KW - Microalgae
KW - Monodus subterraneus
KW - Porphyridium cruentum
KW - SAN 9785
KW - eicosapentaenoic acid
KW - fatty acid biosynthesis
KW - molecular species
UR - http://www.scopus.com/inward/record.url?scp=0030184111&partnerID=8YFLogxK
U2 - 10.1016/0031-9422(96)00053-2
DO - 10.1016/0031-9422(96)00053-2
M3 - Article
AN - SCOPUS:0030184111
SN - 0031-9422
VL - 42
SP - 1025
EP - 1029
JO - Phytochemistry
JF - Phytochemistry
IS - 4
ER -