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Isolation of the Flagellar Swelling and Identification of Retinal in the Phototactic Flagellate, Ochromonas danica (Chrysophyceae)
Author(s) -
WALNE PATRICIA L.,
PASSARELLI VINCENZO,
LENZI PAOLA,
BARSANTI LAURA,
GUALTIERI PAOLO
Publication year - 1995
Publication title -
journal of eukaryotic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 1066-5234
DOI - 10.1111/j.1550-7408.1995.tb01533.x
Subject(s) - euglena gracilis , biology , flagellate , phototaxis , rhodopsin , flagellum , isolation (microbiology) , retinal , chloroplast , botany , biochemistry , microbiology and biotechnology , gene
Ochromonas danica, a freshwater, planktonic chrysophyte, is capable of sensing the light conditions of its environment. This biflagellate alga has a swelling near the base of the short flagellum and a chloroplastidic stigma in close association with it. A procedure is described for the isolation of this three dimensional flagellar swelling, the presumed photoreceptor. In contrast to an earlier method developed for the isolation of the paraflagellar swelling from Euglena gracilis, the protocol reported here for Ochromonas results in higher yields that should facilitate future biochemical investigations and could open avenues of investigation for the isolation and purification of the presumptive receptor protein. To verify the hypothesis that a rhodopsin‐like protein might be present in this alga, we applied a standard extraction procedure successfully used in the identification of retinal. We here report the purification and identification of all‐trans retinal in Ochromonas cells by column chromatography, HPLC and GC‐MS. Since retinal is the chromophore of rhodopsin‐like proteins, this finding may suggest that in these unicellular algae, too, a rhodopsin‐like protein could be the photoreceptor pigment.