ANALYSIS OF ANTI-ACHE FACTORS IN CYANOBACTERIAL BLOOM SAMPLES

Barros, L. P.(1), Romero, A.H.(1), Yunes, J.S.(1), MonSerrat, J.M.(2)

(1)Unidade de Pesquisas em Cianobactérias, FURG, RS, Brazil, (2)Departamento de Ciências Fisiológicas, FURG, RS, Brazil

Cyanobacteria of the genera Anabaena can produce an organophosphorous-like toxin (anatoxina-a(S)). Previous works (Monserrat et al, 2000, Barros, 2002) demonstrated  the anticholinesterasic action of aqueous extracts containing the cyanobacterium  Anabaena spiroides from South Brazilian waters. The same authors also developed an optimized protocol based on Ellman (1961) to be applied in cyanobacterial bloom samples. The present  work tested that protocol on the extraction of anticholinesterasic factors of environmental samples from Brazil and other countries containing predominantly Anabaena spiroides cells. Samples taken directly from blooms and scums were identified and quantified  in cell numbers, lyophilized at –30^oC and  sent to UPC-FURG, RS. Lyophilized powders were dissolved in ethanol, sonicated and  filtered. The final solution was  evaporated  at 40^oC, ressuspended in chloroform and washed in distilled ater pH 3,3. The extract was incubated during one hour at 25^oC with the enzyme acetylcholinesterase, AChE (Sigma, USA). The enzyme activity was measured by spectophotometry. Sixteen samples from public drinking-water reservoirs, were tested. Samples produced an  AChE inhibition from 2,57 to 11,12% at  variable number of A.  spiroides cells from 428  to 10,132 cells mL^-1. However, in a single bloom sample with the number of cells higher than 100,000 cells.mL^-1 AChE inhibition reached up to 31%. Environmental samples containing Planktothrix agardhi  produced AChE inhibitions from 6,49 to 7,56% while the number of cells varied from 15,666 to 137,000 cells mL^-1.  Bloom samples containing single or predominant species of Anabaena circinalis produced a 0% AChE inhibition. The present work suggested that  the increase on AChE inhibition observed may be directly related to the number of cells of the especies  A . spiroides  or P. aghardii . However, further analysis will be necessary to draw a possible linearity between those parameters.

CORRESPONDENCE TO:

João Sarkis Yunes, UPC - Prédio da Hidroquímica- Campus Carreiros da FURG, Caixa Postal 474,  Rio Grande, RS, CEP: 96.201-900, Brasil, Email: dqmsarks@super.furg.br