Interactive effects of UV-B and copper on photosynthetic activity of the cyanobacterium Anabaena doliolum

Interactive effects of UV-B and Cu on photosynthesis, uptake and metabolism of nutrients in a green alga Chlorella vulgaris under simulated ozone column.

“…The sensitivity of PS II to Cu agrees well with the findings of Rai et al (1991), where heavy metals were found to inhibit electron transport at the oxidizing side of PS II or destroy the photosynthetic membranes, consequently inactivating the PS II reaction center. The consumption of 02, instead of evolution, by PS II after exposure to both the doses of UV-B and a LC50 dose of Cu might be due to the arrest of 02-evolution and increase in respiration rate of the test alga as reported by Goyal and Tolbert (1991) and Rai et al (1995) for Chlamydomonas reinhardtii and Anabaena doliolum, respectively. It is pertinent to mention that algal cells treated with UV-B in the presence of two dosages of ozone depicted higher 02-evolution and increased activity of ETC than the control.…”

“…This is likely to alter the amount of energy required for the incorporation of nitrogen and other nutrients since the transport of nitrogenous compounds is effected through ATP-dependent permease. In other words, a decrease in the uptake of these nutrients constitutes the secondary response to the primary UV-B radiation damage of ETC (Rai et al, 1995). The non-competitive inhibition of these nutrients by UV-B (Fig.…”

“…The inhibition of ATPase activity after UV-B exposure was also reported by Murphy (11 983). Since ATPase activity is primarily dependent on the ATP pool, reduction of the cellular ATP pool size following UV-B and metal exposure (Rai et al, 1995) may inhibit the enzyme activity, leading to a decrease of nutrient uptake. The synergistic inhibition of nutrient uptake (p<0.05, f-test) (particularly N03-, urea and P043-; Table 2) under the combined stress of UV-B+Cu could be directly related to the reduced ATPase activity (Table 3), as uptake of nutrients is an energy-dependent process (Oelmuller et al, 1988).…”

Combined Effects of Trace Metals and Light on Photosynthetic Microorganisms in Aquatic Environment

“…Significant increase of intracellular Cu was also found in the cyanobacterium Anabaena doliolum after short-term exposure to UVB radiation. However, under such conditions, it is possible that the intracellular increase induced by UVR was not associated with metal cellular uptake alteration but to membrane damages [76].…”

“…A direct correlation was observed between light-associated variations of intracellular Cu, Cd and Zn concentration and growth, photosynthetic activity and oxidative stress [72,75,76]. Even less is known about sub-cellular metal distribution and other detoxification strategies, therefore further studies are highly sought to better elucidate the possible role of light irradiation on trace metal toxicokinetics.…”