RESUMEN
An investigation was directed towards the antiacetylcholinesterase activity of the acid aqueous and methanolic extracts of five cyanobacterial taxa, which encompasses an enzymatic inhibition essay and the evaluation of the physiological responses of mice to cyanobacterial extracts along with toxicological observations. The strains Calothrix sp. CCIBt 3320, Tolypothrix sp. CCIBt 3321, Phormidium cf. amoenum CCIBt 3412, Phormidium sp. CCIBt 3265, and Geitlerinema splendidum CCIBt 3223 were from the São Paulo Botanical Institute Cyanobacterial Culture Collection and all of them showed inhibitory effect on acetylcholinesterase activity (in vitro) and caused systemic effects similar to those described for anticholinesterase drugs (in vivo). With the exception of G. splendidum and Tolypothrix sp. strains, all extracts produced reversible antiacetylcolinesterase effects in mice. Complementary histopathological studies were carried out on tissues from animals administered with Phormidium sp. and P. cf. amoenum.
RESUMEN
Complementary chromatic adaptation, a well-established phenomenon in some blue-green algae, has been observed in Calothrix clavata, a heterocystous blue-green alga of the family Rivulariaceae. The chromatic adaptation has been observed for fluorescent and incandescent light by measuring the absorption spectra. The material grown in fluorescent light forms more of phycoerythrin whereas more of phycocyanin tends to be formed in incandescent light. Besides this, photoreversal was observed by transferring the incandescent light grown alga to fluorescent light conditions and vice-versa. Effect of photoreversal and chromatic adaptation has also been discussed for this alga under different monochromatic light conditions. The influence of different light conditions on morphological changes, heterocysts and hormogonia formation has also been investigated. Both chromatic adaptation and photomorphogentic phenolmena in this alga show the involvement of some photoreversible (red:green) pigment.