Applications of comet and MTT assays in studying Dunaliella algae species

Abstract

Chloroplasts and unicellular algae genomes, are the most important and vital intracellular organelles which determine the cells physiological performance. Using Comet and MTT assay technics in algal studies, will provide researchers prominent features about both their photosynthesis and genomes. Using two unicellular algal groups, Dunaliella salina (orange) and Dunaliella viridis (green), collected from a hypersaline lake (Maharloo lake) located east of Shiraz, Iran, MTT and Comet assays along with their trouble shootings were used to study these two algae. Results showed that, MTT was reduced due to the presence of oxidoreductive enzymes both in photosynthetic reaction centers and in electron transport chains. It was concluded that, MTT reduction in unicellular algal cells, mostly reflects the chloroplasts activity. The rates of light absorbance at λ = 570 nm due to MTT reduction for 100 000 D. salina cells/well (R2 = 0.9457) as well as for 160 000 D. viridis cells/well (R2=9838) were the same as equal to 1. Due to the presence of beta-carotene in D. salina cells, lower number of cell was required to give the same absorbance as compared to D. viridis. In continuation of this study, non-physiological apoptosis cells death caused by Cis‑platinum drug was investigated in these two algal species. Using Comet assay, the DNA damage was determined in both positive and negative control groups. The tail averages in positive control group and in negative control group, were 14.9 % and 0.73 % respectively. Unicellular aquatic algae that lack cell wall, are suitable models to be used in such studies. We would like to recommend the application of MTT and Comet assays technics due to their high sensitivities for revealing damages done to both photosynthetic system and to DNA which will be effective tools for monitoring the biological and non-biological environmental hazards.