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In order to contribute to the understanding of its response to metal stress, Ulva lactuca (L.) was treated with different concentration of chromium (VI) (0.2, 0.5, 1, and 5 mM K2CrO4), and alterations in Fv/Fm ratio (maximal photochemical efficiency of PSII) and cell viability were investigated. | Turk J Biol 34 (2010) 119-124 © TÜBİTAK doi:10.3906/biy-0810-3 Effects of Chromium VI stress on green alga Ulva lactuca (L.) Dilek ÜNAL1,*, Nuray O. IŞIK2, Atakan SUKATAR1 1 Department of Biology, Faculty of Science, Ege University, İzmir - TURKEY 2Department of Leather Engineering, Ege University, İzmir - TURKEY Received: 06.10.2008 Abstract: In order to contribute to the understanding of its response to metal stress, Ulva lactuca (L.) was treated with different concentration of chromium (VI) (0.2, 0.5, 1, and 5 mM K2CrO4), and alterations in Fv/Fm ratio (maximal photochemical efficiency of PSII) and cell viability were investigated. Significant alterations of the maximal photochemical efficiency of PSII (Fv/Fm) ratio were observed in response to the increase in chromium concentration. The Fv/Fm ratio decreased in Ulva lactuca following 2 h treatment with 1 and 5 mM Cr(VI) solution. The cell viability was decreased in cells exposed to higher Cr(VI) concentrations. Thallus cell morphology was altered in thalli exposed to chromium. A cytotoxic effect of chromium was demonstrated for the first time using acridine orange/ethidium bromide staining in macroalgae. In 1 and 5 mM of Cr(VI) treated samples, the rate of necrotic cells increased about 76.93% and 84.23%, respectively. Key words: Chromium VI, photosynthesis, Ulva lactuca, acridine orange/ethidium bromide staining Yeşil Alg Ulva lactuca (L.) üzerinde Krom (VI) Stresinin Etkileri Özet: Farklı konsantrasyonlarda krom (VI) (0,2, 0,5, 1 ve 5 mM K2CrO4) uygulaması yapılan Ulva lactuca (L.)’da metal stresine yanıt olarak PSII fotosentetik kuantum verimi, hücre canlılığı, ve sitotoksik etkiler üzerindeki değişimler araştırılmıştır. Krom konsantrasyonundaki artışa bağlı olarak fotosentetik kuantum verim (Fv/Fm) oranında önemli ölçüde değişimler olduğu gözlenmiştir. U. lactuca’nın 2 saat, 1 ve 5 mM Cr(VI) uygulanmasını takiben Fv/Fm oranı düşmüştür. Evan’s blue alınım sonuçları ise 1 ve 5 mM Cr(VI) uygulanmış .
