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Discovery of Rare and Highly Toxic Microcystins from Lichen-Associated Cyanobacterium Nostoc sp . Strain IO-102-I. Ilona Oksanen, 2004.The production of hepatotoxic cyclic heptapeptides, microcystins, is almost exclusively reported from planktonic cyanobacteria . Here we show that a terrestrial cyanobacterium Nostoc sp . strain IO-102-I isolated from a lichen association produces six different microcystins . Microcystins were identified with liquid chromatography-UV mass spectrometry by their retention times, UV spectra, mass fragmentation, and comparison to microcystins from the aquatic Nostoc sp . strain 152 . The dominant microcystin produced by Nostoc sp . strain IO-102-I was the highly toxic [ADMAdda5]microcystin-LR, which accounted for ca . 80% of the total microcystins . We assigned a structure of [DMAdda5]microcystin-LR and [D-Asp3,ADMAdda5]microcystin-LR and a partial structure of three new [ADMAdda5]-XR type of microcystin variants . Interestingly, Nostoc spp . strains IO-102-I and 152 synthesized only the rare ADMAdda and DMAdda subfamilies of microcystin variants . Phylogenetic analyses demonstrated congruence between genes involved directly in microcystin biosynthesis and the 16S rRNA and rpoC1 genes of Nostoc sp . strain IO-102-I . Nostoc sp . strain 152 and the Nostoc sp . strain IO-102-I are distantly related, revealing a sporadic distribution of toxin production in the genus Nostoc . Nostoc sp . strain IO-102-I is closely related to Nostoc punctiforme PCC 73102 and other symbiotic Nostoc strains and most likely belongs to this species . Together, this suggests that other terrestrial and aquatic strains of the genus Nostoc may have retained the genes necessary for microcystin biosynthesis . Teschoviruses as Indicators of Porcine Fecal Contamination of Surface Water. Miguel Angel Jiménez-Clavero, 2003.Teschoviruses specifically infect pigs and are shed in pig feces . Hence, their presence in water should indicate contamination with pig fecal residues . To assess this hypothesis, we have developed a real-time reverse transcriptase PCR (RT-PCR) method that allows the quantitative detection of pig teschovirus (PTV) RNA . The method is able to detect 92 fg of PTV RNA per ml of sample . Using this method, we have detected the presence of PTV RNA in water and fecal samples from all pig farms examined (n = 5) . Feces from other animal species (cattle, sheep, and goats) were negative in this test . To compare the PTV RNA detection method with conventional chemical determinations currently in use for evaluation of water contamination, we analyzed water samples collected downstream from a pig slurry spillage site . We have found a positive correlation within both types of determinations . The sensitivity of the PTV detection assay was similar to that achieved by unspecific organic matter determination and superior to all other conventional chemical analyses performed . Furthermore, the new method is highly specific, revealing the porcine origin of the contamination, a feature that is lacking in currently available methods for the assessment of water contamination .
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