Sathasivam Ramaraj, Ki Jang-Seu
Department of Biotechnology, Sangmyung University, Seoul, 03016, South Korea.
Scripps Institution of Oceanography, University of California San Diego, San Diego, CA, 92037, USA.
Mol Biol Rep. 2019 Feb;46(1):1167-1179. doi: 10.1007/s11033-018-04583-9. Epub 2019 Jan 16.
The green microalga, Tetraselmis suecica, is commonly used in scientific, industrial, and aquacultural purposes because of its high stress tolerance and ease of culture in wide spectrums of environments. We hypothesized that carotenoids help to protect Tetraselmis cells from environmental stress by regulating genes in biosynthetic pathways. Here, we determined three major carotenogenic genes, phytoene synthase (PSY), phytoene desaturase (PDS), and β-lycopene cyclase (LCY-B) in T. suecica, and examined the physiological parameters and gene expression responses when exposed to redox-active metals and non-redox-active metals. Phylogenetic analyses of each gene indicated that T. suecica clustered well with other green algae. Real-time PCR analysis showed that TsPSY, TsPDS, and TsLCY-B genes greatly responded to the redox-active metals in CuSO followed by CuCl, but not to the non-redox-active metals. The redox-active metals strongly affected the physiology of the cells, as determined by cell counting, reactive oxygen species (ROS) imaging, and photosynthetic efficiency. This suggests that carotenoids protect the cells from oxidative damage caused by metals, thereby contributing to cell survival under various stress conditions.
绿色微藻——瑞典四爿藻（Tetraselmis suecica），因其具有高胁迫耐受性且易于在各种环境中培养，常用于科学、工业和水产养殖目的。我们推测类胡萝卜素通过调节生物合成途径中的基因来帮助保护瑞典四爿藻细胞免受环境胁迫。在此，我们确定了瑞典四爿藻中的三个主要类胡萝卜素生成基因，即八氢番茄红素合酶（PSY）、八氢番茄红素去饱和酶（PDS）和β-番茄红素环化酶（LCY-B），并研究了其在暴露于氧化还原活性金属和非氧化还原活性金属时的生理参数和基因表达反应。对每个基因的系统发育分析表明，瑞典四爿藻与其他绿藻聚类良好。实时PCR分析表明，TsPSY、TsPDS和TsLCY-B基因对硫酸铜中的氧化还原活性金属反应强烈，其次是氯化铜，但对非氧化还原活性金属无反应。通过细胞计数、活性氧（ROS）成像和光合效率测定发现，氧化还原活性金属强烈影响细胞生理。这表明类胡萝卜素保护细胞免受金属引起的氧化损伤，从而有助于细胞在各种胁迫条件下存活。
