Short term effect of ultraviolet-B radiation on photosystem 2 photochemistry in the cyanobacteriumSynechococcus 6301

Subramanyam, Rajagopal; Murthy, S. D. S.

doi:10.1007/bf02879646

Cited by 9 publications

(3 citation statements)

References 10 publications

(1 reference statement)

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“…M16.1, for which fast specific degradation of the distal PBS hexamers (PEII) was evidenced by MpeB immunoblotting (Figure 4a). Our results are comparable to previous studies led in other cyanobacteria that pointed out serious PBS perturbations in response to ultraviolet (Lao and Glazer, 1996;Rajagopal and Murthy, 1996;Rinalducci et al, 2006;Six et al, 2007b), HL (Tamary et al, 2012) and temperature stress (Li et al, 2001;Stoitchkova et al, 2007), and thus suggests that PBS uncoupling and dismantling is a usual consequence of environmental stress in cyanobacteria. It is, however, worth noting that the highly fluorescent-free PE may also constitute a way of energy dissipation through fluorescence during a stress period.…”

Section: Discussionsupporting

confidence: 91%

Connecting thermal physiology and latitudinal niche partitioning in marine Synechococcus

Pittera

Humily

Thorel³

et al. 2014

The ISME Journal

135

171

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Marine Synechococcus cyanobacteria constitute a monophyletic group that displays a wide latitudinal distribution, ranging from the equator to the polar fronts. Whether these organisms are all physiologically adapted to stand a large temperature gradient or stenotherms with narrow growth temperature ranges has so far remained unexplored. We submitted a panel of six strains, isolated along a gradient of latitude in the North Atlantic Ocean, to long-and short-term variations of temperature. Upon a downward shift of temperature, the strains showed strikingly distinct resistance, seemingly related to their latitude of isolation, with tropical strains collapsing while northern strains were capable of growing. This behaviour was associated to differential photosynthetic performances. In the tropical strains, the rapid photosystem II inactivation and the decrease of the antioxydant b-carotene relative to chl a suggested a strong induction of oxidative stress. These different responses were related to the thermal preferenda of the strains. The northern strains could grow at 10 1C while the other strains preferred higher temperatures. In addition, we pointed out a correspondence between strain isolation temperature and phylogeny. In particular, clades I and IV laboratory strains were all collected in the coldest waters of the distribution area of marine Synechococus. We, however, show that clade I Synechococcus exhibit different levels of adaptation, which apparently reflect their location on the latitudinal temperature gradient. This study reveals the existence of lineages of marine Synechococcus physiologically specialised in different thermal niches, therefore suggesting the existence of temperature ecotypes within the marine Synechococcus radiation.

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Section: Discussionsupporting

confidence: 91%

Connecting thermal physiology and latitudinal niche partitioning in marine Synechococcus

Pittera

Humily

Thorel³

et al. 2014

The ISME Journal

135

171

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“…UV-B also induces structural and functional photodamage to the PBsomes (Sinha et al 1995;Lao and Glazer 1996;Araoz and Hader 1997;Lorenz et al 1997;Pandey et al 1997;Sah et al 1998;Rajagopal et al 1998Rajagopal et al , 1999Jha et al 2000). Earlier studies indicated that exposure of Synechococcus to a high intensity of UV-B for short duration mainly causes the dissociation of PBsomes (Rajagopal and Murthy 1996b;Sah et al 1998). Earlier, we reported that exposure of Spirulina platensis trichomes to moderateintensity UV-B (1.9 mW m )2 ) for 9 h caused the loss of the anchor polypeptide (85.5 kDa) (Rajagopal et al 1998) and Chl antenna complexes .…”

Section: Introductionmentioning

confidence: 93%

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

et al. 2005

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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 muE 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 O(2) evolution, absorption, circular dichroism (CD) spectra, and ultrastructure. At low intensity, UV-B induced loss in PS II-catalyzed O(2) 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.

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“…Until recently, most studies about UV effects on cyanobacteria have been carried out on freshwater strains (Lao and Glazer 1996;Rajagopal and Murthy 1996;Pandey et al 1997;Sinha et al 1995;Rajagopal et al 1998;Sah et al 1998;Rinalducci et al 2006). These works demonstrated that UV-B exposure inhibits O 2 evolving, induces perturbations of energy transfer and degradation of allophycocyanin and/or phycocyanin.…”

Section: Introductionmentioning

confidence: 98%

UV-induced phycobilisome dismantling in the marine picocyanobacterium Synechococcus sp. WH8102

et al. 2007

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The marine picocyanobacterium Synechococcus sp. WH8102 was submitted to ultraviolet (UV-A and B) radiations and the effects of this stress on reaction center II and phycobilisome integrity were studied using a combination of biochemical, biophysical and molecular biology techniques. Under the UV conditions that were applied (4.3 W m(-2) UV-A and 0.86 W m(-2) UV-B), no significant cell mortality and little chlorophyll degradation occurred during the 5 h time course experiment. However, pulse amplitude modulated (PAM) fluorimetry analyses revealed a rapid photoinactivation of reaction centers II. Indeed, a dramatic decrease of the D1 protein amount was observed, despite a large and rapid increase in the expression level of the psbA gene pool. Our results suggest that D1 protein degradation was accompanied (or followed) by the disruption of the N-terminal domain of the anchor linker polypeptide LCM, which in turn led to the disconnection of the phycobilisome complex from the thylakoid membrane. Furthermore, time course analyses of in vivo fluorescence emission spectra suggested a partial dismantling of phycobilisome rods. This was confirmed by characterization of isolated antenna complexes by SDS-PAGE and immunoblotting analyses which allowed us to locate the disruption site of the rods near the phycoerythrin I-phycoerythrin II junction. In addition, genes encoding phycobilisome components, including alpha-subunits of all phycobiliproteins and phycoerythrin linker polypeptides were all down regulated in response to UV stress. Phycobilisome alteration could be the consequence of direct UV-induced photodamages and/or the result of a protease-mediated process.

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Short term effect of ultraviolet-B radiation on photosystem 2 photochemistry in the cyanobacteriumSynechococcus 6301

Abstract: Exposure of intact cells of the Synechococcus 6301 to UV-B radiation induced a loss in photosystem 2 (PS 2) electron transport activity prior to the alteration in pigment complexes. Thus the degradation of PS 2 was not directly related to pigment alteration.

Cited by 9 publications

References 10 publications

Connecting thermal physiology and latitudinal niche partitioning in marine Synechococcus

Connecting thermal physiology and latitudinal niche partitioning in marine Synechococcus

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

UV-induced phycobilisome dismantling in the marine picocyanobacterium Synechococcus sp. WH8102

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