Synthesis, configuration assignment, and simultaneous quantification by liquid chromatography coupled to tandem mass spectrometry, of dihydroanatoxin-a and dihydrohomoanatoxin-a together with the parent toxins, in axenic cyanobacterial strains and in environmental samples

Effects of nitrogen and phosphorus on anatoxin-a, homoanatoxin-a, dihydroanatoxin-a and dihydrohomoanatoxin-a production by Phormidium autumnale

“…Similar results have been found in environmental samples where dihydrogen-derivatives consistently comprise well over 50% of the total anatoxin concentration (Heath et al, 2011;Mann et al, 2012;Wood et al, 2010Wood et al, , 2012. The physiological roles of the variants are unknown, and it is difficult to speculate why under the nitrogen and phosphorus concentrations in these mono-culture experiments why dihydrogen products should be favoured over ATX and HTX analogs.…”

“…blooms, ATX, HTX, dhATX and dhHTX are almost always detected simultaneously, however, the relative concentrations are variable (Heath et al, 2011;Mann et al, 2012;Wood et al, 2012). In some instances, over 90% of the anatoxin concentration are dihydrogen products (Heath et al, 2011).…”

“…Recently the putative gene cluster involved in ATX and HTX production was characterised, with the pathway leading to their synthesis beginning with the amino acid proline (M ejean et al, 2009). It has been suggested that dhATX and dhHTX may be degradation products of ATX and HTX respectively (Stevens and Krieger, 1991), however, little is known about the enzymatic steps leading to their synthesis (Mann et al, 2012). In addition, the biochemical mechanisms responsible for variations in relative ratios of ATX, HTX, dhATX and dhHTX in biological samples are not fully understood.…”

Identification of genes for anatoxin-a biosynthesis in Cuspidothrix issatschenkoi

“…However, the methylation domain alone cannot be responsible for the different ratios of homoanatoxin-a versus anatoxin-a in cyanobacterial strains (Mann et al, 2012), and the competition between methylation reaction and release of 11-carboxylanatoxin-a from multienzyme should be considered. The fact that Oscillatoria sp.…”

Co-occurrence of microcystin and anatoxin-a in the freshwater lake Aydat (France): Analytical and molecular approaches during a three-year survey

“…The LC/MS-MS protocol used in this study was adapted from those of Furey et al (2005) and Mann et al (2012). Samples were separated on an Alliance 2695 HPLC (Waters), with an uptisphere C18-2 strategy column (2.1 Â 150 mm, 3 mm particle size).…”