Mercury-selenium Interaction in Rice Investigated with Metallomics Approach

Aug 22, 2014     Email"> PrintText Size

Metallomics mainly focuses on the global and systematic understanding of metal uptake, transport, role and excretion in biological systems, and exploring the biological effects of absorption, distribution, metabolism and excretion of metal-related materials and their interactions with genes, proteins, metabolites and other biological molecules in biological systems.

IHEP (Institute of High Energy Physics) scientists ZHAO Jiating, LI Yufeng, GAO Yuxi and others have investigated the mercury-selenium (Hg/Se) interaction in rice plants in controlled lab conditions, using metallomics methods to simulate the real-life situation in Qinzhen and Wanshan, Guizhou Province. The results (Selenium modulates mercury uptake and distribution in rice (Oryza sativa L.), in correlation to mercury species and exposure level) were recently published online in the RSC journal Metallomics.

The SRXRF measurement in the present study was partly accomplished at the Beijing Synchrotron Radiation Facility, with the assistance of Prof. CHEN Dongliang et al.

Rice cultured in Hg- and/or Se-contaminated fields is a major source of Hg/Se intake for humans. The soil of Wanshan District, Guizhou, contains elevated levels of both Hg and Se. In this study, the effects of Se on the absorption, transportation and accumulation of Hg in hydroponic and soil-cultured rice plants were examined. It was shown that inorganic mercury (IHg) mainly accumulates in the rice root. In contrast to IHg, methylmercury (MeHg) can be concentrated in the rice grain, and MeHg in the rice grain may account for over 40% of the total Hg quantity present in the rice. Se can protect against Hg phytotoxicity in rice and inhibit IHg accumulation in rice tissues, but no remarkable effect on MeHg accumulation was observed at a low dosage of Se exposure. These discrepancies imply different mechanisms for IHg and MeHg absorption and accumulation in rice, which needs further investigation.

This study illustrates that Se plays an important role in modulating Hg uptake, transportation and accumulation in rice. Se is therefore considered a naturally existing element which can effectively reduce Hg accumulation in rice grains. This may have significant implications for food quality.

Besides rice plants, the IHEP scientists also used metallomics methods to study the mercury-selenium interaction in garlic, C. elegans, mice, rats and human beings.