ISSN:
0886-1544
Keywords:
desmids
;
videomicrography
;
photokinesis
;
photophobic response
;
photophosphorylation
;
photosynthesis
;
phototaxis
;
uncouplers
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
The effects of the uncouplers CCCP and DNP on photokinesis, phototaxis, and the photophobic response in the desmid Cosmarium have been studied both in population systems and by videomicrographic, single-cell analysis. Light-dependent motility is specifically inhibited by both uncouplers, indicating that photokinesis is driven by photophosphorylation. In population experiments, phototaxis and accumulations in light traps due to photophobic responses are inhibited by drug concentrations comparable to those that inhibit photokinesis. Analysis of single-cell behavior demonstrated, however, that neither photophobic responses elicited by an increase in light intensity (step-up response) nor by a decrease (stepdown response) are inhibited, as long as the reduced motility allows the organisms to cross a light--dark border. Phototactic orientation is not impaired by DNP in the single cell analysis, but CCCP significantly reduced the degree of orientation. The results indicate that, although chlorophyll is the photoreceptor for all three photoresponses, at least the photophobic response is independent of both the photosynthetic electron transport chain and photophosphorylation.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cm.970020106
