Journal article


Carotenoids in the eyespot apparatus of the flagellate green alga Spermatozopsis similis: Adaptation to the retinal-based photoreceptor


Publication Details
Author(s): Grung M, Kreimer G, Calenberg M, Melkonian M, Liaaen-Jensen S
Journal: Planta
Publisher: Springer Verlag (Germany)
Publication year: 1994
Volume: 193
Journal issue: 1
Pages range: 38-43
ISSN: 0032-0935

Abstract

Isolated intact eyespot apparatuses, the photoreceptive organelles involved in blue-light-mediated photoresponses of flagellate green algae, were analyzed regarding their carotenoid composition. Carotenoids from the eyespot apparatuses of Spermatozopsis similis were identified by high-performance liquid chromatography, visible-light absorption spectra, mass spectroscopy and by H-1-nuclear magnetic resonance spectroscopy (carotenes), and compared with those of whole-cell extracts. Both extracts contained beta,beta-carotene, beta,psi-carotene (formerly gamma-carotene), lycopene, lutein, zeaxanthin, violaxanthin and all-E- and 9'-Z-neoxanthin. The relative carotenoid compositions, however, differed significantly. A twofold relative increase in the total carotene level was evident in the fraction enriched in eyespot apparatuses. This was mainly due to an increase in the monocyclic beta,psi-carotene and the aliphatic lycopene, whereas the relative content of beta beta-carotene remained unchanged. On the other hand a relative decrease in the total xanthophyll content, especially of lutein and the epoxidic carotenoid neoxanthin, was observed in the eyespot apparatuses compared with the whole-cell extracts. The decrease of the latter resulted almost solely from a reduction of the 9'-Z- rather than the all-E-isomer. The bulk of the carotenes is thought to be localized in the highly organized eyespot lipid globules, which act as a combined quarter-wave interference reflector and absorption screen for the photoreceptor in green algae. The enrichment of beta,psi-carotene and lycopene in the eyespot apparatuses, extending the range of visible light absorption to longer wavelengths, represents an adaptation of the screen to the retinal-based photoreceptor of flagellate green algae and is one of the prerequisites for maximal directional sensitivity of the eyespot apparatus.



How to cite
APA: Grung, M., Kreimer, G., Calenberg, M., Melkonian, M., & Liaaen-Jensen, S. (1994). Carotenoids in the eyespot apparatus of the flagellate green alga Spermatozopsis similis: Adaptation to the retinal-based photoreceptor. Planta, 193(1), 38-43. https://dx.doi.org/10.1007/BF00191604

MLA: Grung, Merete, et al. "Carotenoids in the eyespot apparatus of the flagellate green alga Spermatozopsis similis: Adaptation to the retinal-based photoreceptor." Planta 193.1 (1994): 38-43.

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