Protective effect of supplemental low intensity white light on ultraviolet-B exposure-induced impairment in cyanobacterium Spirulina platensis

Formation of air vacuoles as a possible protective measure

S. Rajagopal, Cosmin Sicora, Z. Várkonyi, L. Mustárdy, Prasanna Mohanty

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13 Citations (Scopus)

Abstract

Intact trichomes of Spirulina platensis were exposed to 1-5 h of low (0.2 mW cm-2) or high (0.6 mW cm-2) intensity UV-B (280-320 nm) radiation, alone or with photosynthetically active radiation (PAR) of supplemental 50 μE m-2 s-1 white light (WL). The mitigating effect of supplemental WL on UV-B induced alterations in Spirulina were investigated by monitoring time-dependent change in photosystem (PS) II mediated O2 evolution, absorption, circular dichroism (CD) spectra, and ultrastructure. At low intensity, UV-B induced loss in PS II-catalyzed O2 evolution, but caused no change in the absorption spectrum. At high intensity, UV-B caused a decrease in absorption by phycobilisomes (PBsomes), which was only partly prevented by the presence of low-intensity supplemental WL. The CD spectral analysis revealed that UV-B exposure caused time-dependent enhancement of the negative psi-type bands at 452 and 689 nm, reflecting alterations in the macroaggregation of chlorophyll-protein complexes. This enhancement of negative PS II-type bands was substantially arrested by the presence of supplemental WL exposure, even when UV-B exposure was continued for 5 h. These changes in UV-B-induced CD spectrum suggest alterations in the antenna structure of Spirulina involving both PBsomes and Chlorophyll a. Thus, supplemental low intensity WL arrests, to large extent, the macroaggregation of pigment-protein complexes. Furthermore, the electron micrographs of Spirulina revealed that UV-B exposure caused disorganization of the cellular ultrastructure, while the inclusion of supplemental WL enhanced the formation of air vacuoles in Spirulina. We suggest that the formation of vacuoles by supplemental WL is a protective feature against UV-B.

Original languageEnglish
Pages (from-to)181-189
Number of pages9
JournalPhotosynthesis Research
Volume85
Issue number2
DOIs
Publication statusPublished - Aug 2005

Fingerprint

Spirulina
Spirulina platensis
white light
Cyanobacteria
Ultraviolet Rays
Vacuoles
vacuoles
protective effect
ultraviolet radiation
Air
Light
air
Photosystem II Protein Complex
circular dichroism spectroscopy
Circular Dichroism
Phycobilisomes
Dichroism
photosystem II
phycobilisome
Chlorophyll Binding Proteins

Keywords

  • Chl a antennas
  • Photosynthetic active radiation
  • Phycobilisomes
  • Ultrastructure
  • Ultraviolet-B
  • Vacuoles

ASJC Scopus subject areas

  • Plant Science

Cite this

@article{1e2a5f422a0a457b972c0c20332538b5,
title = "Protective effect of supplemental low intensity white light on ultraviolet-B exposure-induced impairment in cyanobacterium Spirulina platensis: Formation of air vacuoles as a possible protective measure",
abstract = "Intact trichomes of Spirulina platensis were exposed to 1-5 h of low (0.2 mW cm-2) or high (0.6 mW cm-2) intensity UV-B (280-320 nm) radiation, alone or with photosynthetically active radiation (PAR) of supplemental 50 μE m-2 s-1 white light (WL). The mitigating effect of supplemental WL on UV-B induced alterations in Spirulina were investigated by monitoring time-dependent change in photosystem (PS) II mediated O2 evolution, absorption, circular dichroism (CD) spectra, and ultrastructure. At low intensity, UV-B induced loss in PS II-catalyzed O2 evolution, but caused no change in the absorption spectrum. At high intensity, UV-B caused a decrease in absorption by phycobilisomes (PBsomes), which was only partly prevented by the presence of low-intensity supplemental WL. The CD spectral analysis revealed that UV-B exposure caused time-dependent enhancement of the negative psi-type bands at 452 and 689 nm, reflecting alterations in the macroaggregation of chlorophyll-protein complexes. This enhancement of negative PS II-type bands was substantially arrested by the presence of supplemental WL exposure, even when UV-B exposure was continued for 5 h. These changes in UV-B-induced CD spectrum suggest alterations in the antenna structure of Spirulina involving both PBsomes and Chlorophyll a. Thus, supplemental low intensity WL arrests, to large extent, the macroaggregation of pigment-protein complexes. Furthermore, the electron micrographs of Spirulina revealed that UV-B exposure caused disorganization of the cellular ultrastructure, while the inclusion of supplemental WL enhanced the formation of air vacuoles in Spirulina. We suggest that the formation of vacuoles by supplemental WL is a protective feature against UV-B.",
keywords = "Chl a antennas, Photosynthetic active radiation, Phycobilisomes, Ultrastructure, Ultraviolet-B, Vacuoles",
author = "S. Rajagopal and Cosmin Sicora and Z. V{\'a}rkonyi and L. Must{\'a}rdy and Prasanna Mohanty",
year = "2005",
month = "8",
doi = "10.1007/s11120-005-2439-6",
language = "English",
volume = "85",
pages = "181--189",
journal = "Photosynthesis Research",
issn = "0166-8595",
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T1 - Protective effect of supplemental low intensity white light on ultraviolet-B exposure-induced impairment in cyanobacterium Spirulina platensis

T2 - Formation of air vacuoles as a possible protective measure

AU - Rajagopal, S.

AU - Sicora, Cosmin

AU - Várkonyi, Z.

AU - Mustárdy, L.

AU - Mohanty, Prasanna

PY - 2005/8

Y1 - 2005/8

N2 - Intact trichomes of Spirulina platensis were exposed to 1-5 h of low (0.2 mW cm-2) or high (0.6 mW cm-2) intensity UV-B (280-320 nm) radiation, alone or with photosynthetically active radiation (PAR) of supplemental 50 μE m-2 s-1 white light (WL). The mitigating effect of supplemental WL on UV-B induced alterations in Spirulina were investigated by monitoring time-dependent change in photosystem (PS) II mediated O2 evolution, absorption, circular dichroism (CD) spectra, and ultrastructure. At low intensity, UV-B induced loss in PS II-catalyzed O2 evolution, but caused no change in the absorption spectrum. At high intensity, UV-B caused a decrease in absorption by phycobilisomes (PBsomes), which was only partly prevented by the presence of low-intensity supplemental WL. The CD spectral analysis revealed that UV-B exposure caused time-dependent enhancement of the negative psi-type bands at 452 and 689 nm, reflecting alterations in the macroaggregation of chlorophyll-protein complexes. This enhancement of negative PS II-type bands was substantially arrested by the presence of supplemental WL exposure, even when UV-B exposure was continued for 5 h. These changes in UV-B-induced CD spectrum suggest alterations in the antenna structure of Spirulina involving both PBsomes and Chlorophyll a. Thus, supplemental low intensity WL arrests, to large extent, the macroaggregation of pigment-protein complexes. Furthermore, the electron micrographs of Spirulina revealed that UV-B exposure caused disorganization of the cellular ultrastructure, while the inclusion of supplemental WL enhanced the formation of air vacuoles in Spirulina. We suggest that the formation of vacuoles by supplemental WL is a protective feature against UV-B.

AB - Intact trichomes of Spirulina platensis were exposed to 1-5 h of low (0.2 mW cm-2) or high (0.6 mW cm-2) intensity UV-B (280-320 nm) radiation, alone or with photosynthetically active radiation (PAR) of supplemental 50 μE m-2 s-1 white light (WL). The mitigating effect of supplemental WL on UV-B induced alterations in Spirulina were investigated by monitoring time-dependent change in photosystem (PS) II mediated O2 evolution, absorption, circular dichroism (CD) spectra, and ultrastructure. At low intensity, UV-B induced loss in PS II-catalyzed O2 evolution, but caused no change in the absorption spectrum. At high intensity, UV-B caused a decrease in absorption by phycobilisomes (PBsomes), which was only partly prevented by the presence of low-intensity supplemental WL. The CD spectral analysis revealed that UV-B exposure caused time-dependent enhancement of the negative psi-type bands at 452 and 689 nm, reflecting alterations in the macroaggregation of chlorophyll-protein complexes. This enhancement of negative PS II-type bands was substantially arrested by the presence of supplemental WL exposure, even when UV-B exposure was continued for 5 h. These changes in UV-B-induced CD spectrum suggest alterations in the antenna structure of Spirulina involving both PBsomes and Chlorophyll a. Thus, supplemental low intensity WL arrests, to large extent, the macroaggregation of pigment-protein complexes. Furthermore, the electron micrographs of Spirulina revealed that UV-B exposure caused disorganization of the cellular ultrastructure, while the inclusion of supplemental WL enhanced the formation of air vacuoles in Spirulina. We suggest that the formation of vacuoles by supplemental WL is a protective feature against UV-B.

KW - Chl a antennas

KW - Photosynthetic active radiation

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KW - Ultrastructure

KW - Ultraviolet-B

KW - Vacuoles

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DO - 10.1007/s11120-005-2439-6

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JF - Photosynthesis Research

SN - 0166-8595

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