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Abstract:
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This dissertation includes molecular and phytochemical investigations of the harmful , bloom -forming alga , Prymnesium parvum , including analysis of known polyketide metabolites as a function of salinity and growth . Initially , the development of molecular and phytochemical tools was necessary for the detection and quantification of P . parvum and its associated toxins . Suites of oligonucleotides and molecular beacons were designed for conventional and quantitative multiplex PCR to amplify four species - and gene -specific products simultaneously that were used for the detection and quantitation of P . parvum . This built -in redundancy provided increased confidence in reactions with the positive confirmation of four discrete products . Techniques were also developed for the chemical enrichment of toxins produced by P . parvum . Until now , isolation of “prymnesins” has never been reproduced . Polyketide prymnesins possess unique spectral properties that were used to generate an LC -MS fingerprint that comprised 13 ion species . Preliminary investigations using chemifluorimetric methods were also capable of detecting prymnesins in the pico - and nano -molar range . Environmental samples were tested as an independent assessment of these methods . Lastly , the roles of polyketide prymnesins were analyzed with respect to total hemolytic activity (HA ) as a function of culture age and salinity . Variation in HA of supernatants was statistically significant relative to both variables (p < < 0 .05 ) . Salinity was inversely related to HA wherein cultures growing in 5 -25 psu were 150 -200 % more hemolytic . Total HA was inversely related to culture age during the first three weeks , but positively related to it during the next three weeks . Interestingly , no hemolysis was detected in fractions containing prymnesins from culture supernatants and the majority of hemolysins remained in the aqueous phase . Prymnesins extracted from cells varied significantly over the 6 -week observation period (p < < 0 .05 ) ; HA was positively correlated during the first half and inversely related during the last half of the study . Salinity was directly related to HA from cell extracts , but these effects were not significantly different until the last three weeks . These investigations suggest that polyketide prymnesins are present at much lower quantities than previously believed , and they may not be the key compounds associated with hemolysis due to P . parvum . |