Effects of ultraviolet irradiation on photosynthetic pigments in some filamentous cyanobacteria

Donkor, VA; Dp, Häder

doi:10.3354/ame011143

Cited by 36 publications

(15 citation statements)

References 16 publications

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“…The increase in fluorescence emission peaks with the UV-B treatments (Figure 3) was not accompanied by a shift of the peak to shorter wavelengths as has been reported for larger exposure to UV-B [12]. However, the observed slight decay in fluorescence intensity was probably due to less efficiency in light capture in UV-B irradiated cells and loss in efectivity of energy transfer to the photosynthetic reaction center.…”

Section: Pigmentation and Photosynthesismentioning

confidence: 63%

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Differential Response to Moderate UV-B Irradiation of Two Heterocystous Cyanobacteria Isolated from a Temperate Ricefield

Pérez¹,

Doldán²,

Borsani³

et al. 2012

AiM

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In cyanobacteria both photosynthesis and nitrogen fixation can be affected by UV radiation. Two of the most abundant heterocystous cyanobacteria isolates from a temperate ricefield in Uruguay belonging to Anabaena and Calothrix genus were exposed for 1 or 3 hours to UV-B dosis similar to those to which they are exposed in summer. Anabaena survival after 1 h of UV-B exposure was 10% whereas in Calothrix's was 30%. Both the quantum yields of photosybtem II fluorescence and O 2 photoevolution decreased with time of UV-B exposure for Calothrix and only till 1 h for Anabaena. Only the Calothrix strain presented phycoerithryn as antenna pigment and constitutive UV-B screening mycosporine like aminoacids. In the Anabaena strain, nitrogenase activity was drastically reduced with UV-B irradiation but in Calothrix was not affected. Proline content and lipid peroxidation increased after 3 hours of UV-B exposure only in Anabaena sp. The antioxidant enzyme activities evaluated followed different trends for both isolates, with an increase in superoxide dismutase activity in the Calothrix isolate. These results show that the two nitrogen-fixing cyanobacteria studied have different responses to UV-B radiation and that cyanobacteria diversity may be considered when selecting strains to be used as biofertilizers.

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Section: Pigmentation and Photosynthesismentioning

confidence: 63%

“…A scanning spectrum (300 -750 nm) of immobilized cells exposed for different periods of time to the beam of the spectrophotometer at 280 nm was obtained, according to [12].…”

Section: Absorption Spectramentioning

confidence: 99%

Differential Response to Moderate UV-B Irradiation of Two Heterocystous Cyanobacteria Isolated from a Temperate Ricefield

Pérez¹,

Doldán²,

Borsani³

et al. 2012

AiM

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“…Cyanobacteria are cosmopolitan and must possess a high potential of adaptation to diverse environmental factors. However, UV-B is known to affect processes such as growth, survival, pigmentation and motility, as well as the enzymes of nitrogen metabolism and CO 2 fixation [65,66]. Depending on the species, growth and survival decrease within a few hours of UV-B irradiation.…”

Section: Cyanobacteriamentioning

confidence: 99%

Effects on aquatic ecosystems

Häder

Kumar

Smith

et al. 1998

Journal of Photochemistry and Photobiology B: Biology

334

160

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Regarding the effects of UV-B radiation on aquatic ecosystems, recent scientific and public interest has focused on marine primary producers and on the aquatic web, which has resulted in a multitude of studies indicating mostly detrimental effects of UV-B radiation on aquatic organisms. The interest has expanded to include ecologically significant groups and major biomass producers using mesocosm studies, emphasizing species interactions. This paper assesses the effects of UV-B radiation on dissolved organic matter, decomposers, primary and secondary producers, and briefly summarizes recent studies in freshwater and marine systems.Dissolved organic carbon (DOC) and particulate organic carbon (POC) are degradation products of living organisms. These substances are of importance in the cycling of carbon in aquatic ecosystems. UV-B radiation has been found to break down high-molecular-weight substances and make them available to bacterial degradation. In addition, DOC is responsible for short-wavelength absorption in the water column. Especially in coastal areas and freshwater ecosystems, penetration of solar radiation is limited by high concentrations of dissolved and particulate matter. On the other hand, climate warming and acidification result in faster degradation of these substances and thus enhance the penetration of UV radiation into the water column.Several research groups have investigated light penetration into the water column. Past studies on UV penetration into the water column were based on temporally and spatially scattered measurements. The process of spectral attenuation of radiant energy in natural waters is well understood and straightforward to model. Less known is the spatial and temporal variability of in-water optical properties influencing UV attenuation and there are few long-term observations. In Europe, this deficiency of measurements is being corrected by a project involving the development of a monitoring system (ELDONET) for solar radiation using three-channel dosimeters (UV-A, UV-B, PAR) that are being installed from Abisko (North Sweden, 688N, 198E) to Tenerife (Canary Islands, 278N, 178W). Some of the instruments have been installed in the water column (North Sea, Baltic Sea, Kattegat, East and Western Mediterranean, North Atlantic), establishing the first network of underwater dosimeters for continuous monitoring.Bacteria play a vital role in mineralization of organic matter and provide a trophic link to higher organisms. New techniques have substantially changed our perception of the role of bacteria in aquatic ecosystems over the recent past and bacterioplankton productivity is far greater than previously thought, having high division and turnover rates. It has been shown that bacterioplankton play a central role in the carbon flux in aquatic ecosystems by taking up DOC and remineralizing the carbon. Bacterioplankton are more prone to UV-B stress than larger eukaryotic organisms and, based on one study, produce about double the amount of cyclobutane dimers. Recently, th...

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“…UV-B also inhibits other photosynthetic functions, including expression and activity of ribulose-1,5-bisphosphate carboxylase͞oxygenase (8)(9)(10)(11)(12), the key enzyme of carbon dioxide fixation. In cyanobacteria, UV-B can trigger dissociation and bleaching of the phycobilisome lightharvesting antennae (12)(13)(14)(15)(16), inhibit nitrogenase activity (17)(18)(19), and interfere with cell differentiation (20), although the ecological significance of some severe UV treatments has been questioned (21).…”

mentioning

confidence: 99%

The cyanobacterium Synechococcus resists UV-B by exchanging photosystem II reaction-center D1 proteins

Campbell

Eriksson

Öquist

et al. 1998

Proc. Natl. Acad. Sci. U.S.A.

172

117

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Current ambient UV-B levels can significantly depress productivity in aquatic habitats, largely because UV-B inhibits several steps of photosynthesis, including the photooxidation of water catalyzed by photosystem II. We show that upon UV-B exposure the cyanobacterium Synechococcus sp. PCC 7942 rapidly changes the expression of a family of three psbA genes encoding photosystem II D1 proteins. In wild-type cells the psbAI gene is expressed constitutively, but strong accumulations of psbAII and psbAIII transcripts are In oxygenic photobionts, photosystem II (PSII) is an integral membrane complex that catalyzes the photooxidation of water, with concomitant release of oxygen. Electrons extracted from water are passed to plastoquinone and enter the photosynthetic electron transport chain. The core of the PSII complex is composed of a dimer of two related proteins, D1 and D2, that bind the pigments and cofactors involved in this electron transfer from water to plastoquinone. During active photosynthesis the D1 protein, and to a lesser extent D2, turn over rapidly and are replaced by newly synthesized polypeptides in a PSII repair cycle. Under environmental stress, the repair cycle can be impaired, such that degradation and loss of D1 protein exceeds the rate of replacement (1). This net loss of functional D1 leads to a drop in PSII function and can contribute to photoinhibition, a light-dependent drop in the quantum yield of photosynthesis. Photoinhibition usually occurs when excitation capture exceeds the rate of electron removal from the PSII complex, as can occur when the light intensity exceeds the acclimated irradiance or when the temperature drops below the acclimated level.

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Effects of ultraviolet irradiation on photosynthetic pigments in some filamentous cyanobacteria

Cited by 36 publications

References 16 publications

Differential Response to Moderate UV-B Irradiation of Two Heterocystous Cyanobacteria Isolated from a Temperate Ricefield

Differential Response to Moderate UV-B Irradiation of Two Heterocystous Cyanobacteria Isolated from a Temperate Ricefield

Effects on aquatic ecosystems

The cyanobacterium Synechococcus resists UV-B by exchanging photosystem II reaction-center D1 proteins

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