The eyespot of Euglena gracilis: a microspectrophotometric study.

Abstract:

:The eyespots in cells of streptomycin-bleached strains and of dark-grown cultures of Euglena gracilis, were examined by means of fluorescence microscopy and microspectrophotometry. When viewed with light in the region of 380-500 nm, the stigma appeared as a dark spot. Adjacent to this was a second spot, not seen with white light, but which was seen to fluoresce when excited with radiation at 370 +/- 20 nm. This fluorescence proved to be polarized in contrast to other fluorescing bodies in the cell. The absorption curves, obtained by microspectrophotometry of individual eyespots, were found to consist of two spectral maxima, an A-band in the blue and a B-band in the green. Unlike the A-band, the B-band provided evidence of originating from an anisotropic structure. Relating these data to literature findings, we conclude that the B-band is the absorbance of a pigment in the quasi-crystalline paraflagellar body and the A-band perhaps a pigment in the orange-red stigma. The spectrum of the B-band does not appear to be that of a flavoprotein or of a free carotenoid but its resemblance to the spectrum of rhodopsin is significant in relation to published data for the Chlamydomonas eyespot that suggests the presence of a rhodopsin-like pigment as the photosensitive system responsible for phototaxis in this alga.

journal_name

Vision Res

journal_title

Vision research

authors

James TW,Crescitelli F,Loew ER,McFarland WN

doi

10.1016/0042-6989(92)90151-8

subject

Has Abstract

pub_date

1992-09-01 00:00:00

pages

1583-91

issue

9

eissn

0042-6989

issn

1878-5646

pii

0042-6989(92)90151-8

journal_volume

32

pub_type

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