ISSN:
0886-1544
Keywords:
Euglena flagella
;
laser microsurgery
;
stigma
;
Mg2+
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
When the area of the stigma of Euglena was irradiated with an infrared laser beam at a dose too low to cause permanent loss of motility, a reduction in flagellar motility was observed only when the external medium contained less than 1 mM Mg2+. At these low Mg2+ concentrations, the laser caused a decrease in flagellar frequency and a tendency for the flagellar waveform to shift towards that taken during reversed swimming. This suggests that the effect of the laser irrdiation was to deplete the cells of Mg2+. After the laser pulse the reversal response remained sensitive to the wavelength of the illuminating light. In white light (420-700 nm) 60% of the Euglena showed a reversed waveform; in orange light (530-700 nm) this increased to 90%. This shows that the photoreceptor was not destroyed by the laser irradiation.These experiments were performed on cells that had been impaled on a microelectrode. If direct electric current was passed into the laser-irradiated cells, the current necessary to cause flagellar arrest was 2 to 4 times less than that for cells not laser irradiated.It is concluded that an internal Mg2+ store is present in the Euglena, localized in the area of the paraflagellar swelling; and that the laser irradiation eliminates this Mg2+ store, but at the power used it does not destroy the ability of the stigmaparaflagella to control the flagellar activity.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cm.970020606
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