ISSN:
1615-6102
Keywords:
Action spectra
;
Blue light
;
Euglena
;
Photophobic responses
;
Ultraviolet light
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary Cultures of unicellular algal flagellateEuglena gracilis grown in different conditions were subjected to action spectroscopy for step-down and step-up photophobic responses, respectively. The spectral region was extended into the UV-B/C as well as in the UV-A and visible regions with the Okazaki Large Spectrograph as the monochromatic light source. The photophobic responses of the cells were measured with an individual-cell assay method with the aid of a computerized video motion analyzer. In the UV-A and visible regions, the shapes of the action spectra were the so-called UV-A/blue type. In the newly studied UV-B/C region, new action peaks were found at 270 nm for the step-down response and at 280 nm for the step-up one. The absorption spectrum of flavin adenine dinucleotide (FAD) appeared to fit the action spectrum for the step-up response, whereas the shape of the step-down action spectrum, which has a UV-A peak (at 370 nm) higher than the blue peak (at 450 nm), appeared to be mimicked by the absorption spectrum of a mixed solution of 6-biopterin and FAD. These observations might also account for the fact that the UV-B/C peak wavelength at 270 nm of the action spectrum for the step-down response is shorter by 10 nm than the action spectrum for the step-up response at 280 nm.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01280710
