ISSN:
1432-072X
Keywords:
Astasia longa
;
Chemoaccumulation
;
Chemotaxis
;
Flagellates
;
Hydrogen peroxide
;
Phobic response
;
Riboflavin
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract In the presence of the photosensitizer riboflavin, Astasia accumulates in illuminated fields at high fluence rates. The quenchers of riboflavin excited states, NaN3 and KI, abolish the photodynamic effect of riboflavin. Crocetin, a 1O2 quencher, does not influence the photodynamic action of riboflavin while 1,4-benzoquinone very strongly depresses its effect. This indicates a type I pathway forming H2O2 as a photoproduct. The photodynamic effect is abolished by the addition of 10-5 M catalase which breaks down H2O2. Astasia shows chemoaccumulations around the opening of a capillary filled either with riboflavin (under high intensity irradiation) or H2O2 which proves the hypothesis that the photobehavioral response in the presence of riboflavin is based on a chemoresponse toward H2O2, produced when the dye is irradiated. The accumulation around the capillary opening is not due to a direct chemotactic movement of cells but rather to a chemophobic response which prevents the cells from swimming away from the chemoattractant.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00491911
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