Flos-aquae

Anabaena azollae Anabaena cylindrica Anabaena flos-aquae 0-anabasine [494-52-0] Anabasine [494-52-0] Anabolic steroids Anaerobic digestion Anaerobic treatment Anafranil... 

To accommodate this new finding and the previous results, we considered a new pathway (Scheme 3), in which acetate or its derivative condenses with arginine followed by decarboxylation. Such Claisen-type condensation on alpha-amino acid has some precedent in biochemical systems (6). To prove this hypothesis, we synthesized [2- C, 2-arginine and ornithine and fed to A, flos-aquae (5). 

The freshwater cyanophyte Aphanazomenon flos-aquae (see Chapter 6, by Carmichael), long suspected to contain saxitoxin-like compounds, has been shown to contain saxitoxin and neosaxitoxin, and has been an important tool in the elucidation of saxitoxin biosynthesis (49,50 see Chapter 2, by Shimizu). This research clearly demonstrates that the saxitoxins can be produced by a procaryote thus, the suggestion that bacteria may produce the saxitoxins becomes more plausible. 

Anatoxins. Neurotoxins produced by filamentous Anabaena flos-aquae are called anatoxins (ANTXS) 15). Currently two anatoxins, from different strains of A. flos-aquae, have been isolated and at least partially characterized. ANTX-A from strain (single filament isolate) NRC-44-1 is the first toxin from a freshwater... 

A. flos-aquae Strain NRC-44-1 (Canada, Saskatchewan) Anatoxin-A Secondary amine alkaloid, MW 165 200... 

Aph, flos-aquae Strain NH-1 NH-5 (U.S., New Hampshire) Aphantoxin (neosaxitoxin) Aphantoxin II (saxitoxin) Purine alkaloid MW 315 (neoSTX) MW 299 (STX) 10... 

All known occurrences of ANTX-A production have been from Canada or the United States. More recently, ANTX-A has been detected in A. flos-aquae blooms from Japan (Watanabe, personal communication), Norway (Skulberg, personal communication), and Finland (99). 

Figure 1. Left Anatoxin-a (ANTX-A) hydrochloride. Produced by the freshwater filamentous cyanobacterium Anabaena flos-aquae NRC-44-1. Right Anatoxin-a(s). Produced by the freshwater filamentous cyanobacterium Anabaena flos-aquae NRC-525-17. Bottom Aphantoxin-I (neosaxitoxin) and Aphantoxin-II (saxitoxin) produced by certain strains of the filamentous cyanobacterium Aphantomenon flos-aquae.

Shimizu et al. (56) studied the biosynthesis of the STX analog neoSTX using Aph, flos-aquae NH-1. They were able to confirm its presence in strain NH-1 and to explain the biosynthetic pathway for this important group of secondary chemicals. 

Algal blooms in fresh water ponds occasionally poison livestock and waterfowl. Axenic cultures of Anabaena flos-aquae NRC 44-1 were shown to produce the toxic principle (5) which can be present in the algae and in the water of mature cultures (6). The discovery of the toxin was fortuitous in the sense that AChR agonists do not have a (known) constructive function in the algae evolution of the synthetic pathway was likely a by-product of metabolic pathways in the algae. The compound became evident only through its toxic effects on other organisms. 

Alteromonas species producing sodium channel blockers, 80r,82 Anabaena flos-aquae neurotoxins, 88 toxic principle, 108 Analyses, definition, 43 Anatoxin(s) isolation, 88 types, 88,91 Anatoxin a... 

Parsons and coworkers [174] have published a route to anatoxin-o, which was isolated from strains of freshwater blue-green algae Anabaena flos aqua and is responsible for the death of livestock, waterfowl, and fish [175]. The sequence started... 

Allelopathic Effects of A. flos-aquae on a Motile Alga... 

One role of cyanobacterial allelochemicals may be to alter the motility and distribution of competing photoautotrophs. In a recent study, Kearns and Hunter (2001) examined the effects of toxic metabolites from the filamentous cyanobacterium A. flos-aquae on a unicellular phytoplankton species, Chlamydomonas rein-hardtii. A. flos-aquae synthesizes both microcystins as well as anatoxins, providing the authors with an ecologically relevant opportunity to assess the individual and combinatorial effects of these toxins on an alga. 

Cells of C. reinhardtii were exposed to cell-free filtrates from A. flos-aquae, pure microcystin-LR or anatoxin-a, or combinations of the toxins. Both the position of the cells and the chlorophyll-a concentration of the cultures were observed for 12 days. Exposure to crude extracts as well as to combinations of the toxins significantly decreased chlorophyll levels in the cultures. Furthermore, these compounds were all capable of paralyzing the algae and thus promoted the settlement of C. reinhardtii cells. One intriguing aspect of this dynamic interaction is the separate finding that C. reinhardtii may actually induce toxin synthesis in A. flos-aquae (Kearns and Hunter 2000), essentially signaling its own demise. 

Preufiel K, Stiiken A, Wiedner C, Chorus I, Fastner J (2006) First report of cylindrospermopsin producing Aphanizomenon flos-aquae (Cyanobacteria) from two German lakes. Toxicon... 

APHA Selenastrum capricornutum, Species-dependent Microcystis aeruginosa, between 103 and Anabaena flos-aquae, 50 X 103 Cyclotella sp. Nitzschia sp. Synedra sp. APHAb Growth rate 24 2 32-65 pmol m 2 s 1... 

Fig. 1.—Hydrolysis of Extracellular Polysaccharide Produced by Anahaena flos-aquae A-37. [Key 1, galactose 2, glucose 3, mannose 4, arabinose 5, rhamnose 6, ribose, fucose and 7, xylose.]...

The saxitoxins have also been found in the freshwater cyanophyte Aphanizomenon flos aquae (9,1 ) and, quite recently, in tropical marine coralline algae of the genus Jania (11)... 

Other Peptide Toxin Producing Cyanobacteria. No other cyanobacteria genera have been analyzed for the presence of toxic peptides. Based on toxicity signs however it is thought that peptide toxins are present in certain isolates of Anabaena flos-aquae (J) and Oscillatorla agardhil (9,17). 

Alkaloid Toxins. Only one alkaloid toxin has been chemically defined from the cyanobacteria. This is the secondary amine, 2-acetyl-9-azabicyclo (4-2-1) non-2-ene, called anatoxin-a. It is isolated from the filamentous strain Anabaena flos-aquae NRG-44-1 (18,19). 

Two other suspected alkaloid producing cyanobacteria strains, Anabaena flos-aquae NRC-525-17 and Aphanizomenon flos-aquae NH-5, are now being studied. The toxin of flos-aquae NRC-525-17 (anatoxin-a(s)) is thought to have CNS stimulating properties (7) and that of Aph. flos-aquae NH-5 (aphantoxin) is thought to produce the paralytic shellfish poisons saxitoxin and neosaxitoxin (Fig. 1)... 

Earlier research had already suggested that certain blooms Aph. flos-aquae could produce paralytic shellfish poisons. These studies used water blooms collected from Kezar Lake, New Hampshire (25,30). In 1980 Carmichael isolated a neurotoxic strain of Aph. flos-aquae from a small pond in New Hampshire. These strains have also been shown to produce toxins similar to saxitoxin and neo- axitoxin (23) and are the ones used in the studies presented here. 

Figure 1. Structure of anatoxin-a from Anabaena flos-aquae NRC-44-1, saxitoxin and neosaxitoxin. Saxitoxin and neosaxitoxin is produced by certain species of marine algae and by the freshwater cyanobacteria Aphanizomenon flos-aquae NH-5.

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