Overexpressing heat-shock protein OsHSP50.2 improves drought tolerance in rice.

KEY MESSAGE: OsHSP50.2, an HSP90 family gene up-regulated by heat and osmotic stress treatments, positively regulates drought stress tolerance probably by modulating ROS homeostasis and osmotic adjustment in rice. Heat-shock proteins (HSPs) serve as molecular chaperones for a variety of client proteins in abiotic stress response and play pivotal roles in protecting plants against stress, but the molecular mechanism remains largely unknown. Here, we report an HSP90 family gene, OsHSP50.2, which acts as a positive regulator in drought stress tolerance in rice (Oryza sativa). OsHSP50.2 was ubiquitously expressed and its transcript level was up-regulated by heat and osmotic stress treatments. Overexpression of OsHSP50.2 in rice reduced water loss and enhanced the transgenic plant tolerance to drought and osmotic stresses. The OsHSP50.2-overexpressing plants exhibited significantly lower levels of electrolyte leakage and malondialdehyde (MDA) and less decrease of chlorophyll than wild-type plants under drought stress. Moreover, the OsHSP50.2-overexpressing plants had significantly higher SOD activity under drought stress compared with the wild type. These results imply that OsHSP50.2 positively regulates drought stress tolerance in rice, probably through the modulation of reactive oxygen species (ROS) homeostasis. Additionally, the OsHSP50.2-overexpressing plants accumulated significantly higher content of proline than the wild type under drought stress, which contributes to the improved protection ability from drought stress damage via osmotic adjustment. Our findings reveal that OsHSP50.2 plays a crucial role in drought stress response, and it may possess high potential usefulness in drought tolerance improvement of rice.

Tissue distribution of perfluorinated compounds in farmed freshwater fish and human exposure by consumption.

In the present study, the levels of 14 perfluorinated compounds (PFCs) were analyzed in the blood, liver, muscle, brain, and eggs of popular farmed freshwater fish from Beijing. Perfluorooctane sulfonate (PFOS) was the predominant compound in all samples, with the highest concentration at 70.7 ng/g wet weight. The highest mean levels of PFOS in all tissues were observed in bighead (1.48-22.5 ng/g wet wt) and the lowest in tilapia (0.260-1.63 ng/g wet wt). In addition, perfluoroundecanoic acid was the second dominant PFC in blood, liver, muscle, and eggs, with the highest concentration at 19.2 ng/g wet weight. However, perfluorodecanoic acid levels (less than the limit of detection [LOD] to 0.963 ng/g wet wt) were similar to or slightly higher than perfluoroundecanoic acid levels (

Distribution of perfluorinated compounds in water, sediment, biota and floating plants in Baiyangdian Lake, China.

The distribution of perfluorinated compounds (PFCs) in Baiyangdian Lake, China, was determined in this study. Perfluorooctanoic acid (PFOA) was the dominant PFC in lake water (1.70-73.5 ng L(-1), median 9.72 ng L(-1)), while perfluorooctane sulfonate (PFOS) was the dominant PFC in sediments (0.06-0.64 ng g(-1) dry wt, median 0.19 ng g(-1) dry wt) and in aquatic animals (0.57-13.7 ng g(-1) wet wt, median 2.56 ng g(-1) wet wt). Significant differences in PFC levels were observed among various aquatic animals. We also determined, for the first time, the PFC levels in floating plants, including Ceratophyllum demersum L., Hydrocharis dubia (Bl.) Backer and Salvinia natans (L.), and we found that PFOA and PFNA were the dominant PFCs in these plants. Furthermore, floating plants were observed to have different composition profiles compared to aquatic animals. Geographical differences in PFC levels were also observed, with higher PFC levels in samples from the north part of Baiyangdian Lake than those in the south. The differences in human and industrial activities in different parts of the lake and the discharged wastewater from the Fuhe River may be the major contributors for these geographical differences.

Pilot investigation of perfluorinated compounds in river water, sediment, soil and fish in Tianjin, China.

Detectable PFCs could be found in all samples. Perfluorooctanoic acid (PFOA) was the major PFC in river water, while perfluorooctane sulfonate (PFOS) was dominant in sediment and were 17- to 153-fold higher than those in water. PFCs concentrations in soil were little higher than those in sediment. In fish muscles PFOS showed the highest concentrations. Generally, PFC concentrations in fish were in the following rank order: crucian carp > silver carp> common carp. We suggested that there may be constant and diffuse pollution sources in Tianjin. Point sources also appeared to make significant contribution in the present study.

Concentrations of perfluorinated compounds in human blood from twelve cities in China.

We detected nine perfluorinated compounds (PFCs) in 233 human whole-blood samples collected from 12 cities (from 12 provinces and districts) in China. Perfluorinated compounds could be detected in all blood samples, with perfluorooctane sulfonate (C8, PFOS) as the most prominent PFC. Mean PFOS concentrations were measured at 3.06 to 34.0 µg/L, accounting for the majority of the total perfluorinated compounds (ΣPFCs) (54-87%) in blood samples, except those from Kunming. Perfluorooctane sulfonate and perfluorohexane sulfonate (C6, PFHxS) concentrations were positively correlated in blood samples (p < 0.01). Significant relations among perfluorooctanoate (C8, PFOA), perfluorononanoic acid (C9, PFNA), perfluorodecanoic acid (C10, PFDA), and perfluoroundecanoic acid (C11, PFUnDA) (p < 0.05) were also observed in the present study, indicating that they may come from a similar exposure pathway in China. In general, gender-related differences were found for PFHxS and ΣPFCs concentrations, which were significantly higher in males than in females (p < 0.05). In the 20- to 29-year age group, gender influence was also found for PFHxS and PFOS concentrations. The mean blood concentration of PFOS (10.6 µg/L) in the present study was comparable with results from other countries, while PFOA and PFHxS (1.39 µg/L and 0.57 µg/L, respectively) were often lower. This can probably be attributed to a different exposure pathway of the general population in China as compared to other countries.

Removal of fluoride from aqueous media by Fe3O4@Al(OH)3 magnetic nanoparticles.

A novel magnetic nanosized adsorbent using hydrous aluminum oxide embedded with Fe(3)O(4) nanoparticle (Fe(3)O(4)@Al(OH)(3) NPs), was prepared and applied to remove excessive fluoride from aqueous solution. This adsorbent combines the advantages of magnetic nanoparticle and hydrous aluminum oxide floc with magnetic separability and high affinity toward fluoride, which provides distinctive merits including easy preparation, high adsorption capacity, easy isolation from sample solutions by the application of an external magnetic field. The adsorption capacity calculated by Langmuir equation was 88.48 mg g(-1) at pH 6.5. Main factors affecting the removal of fluoride, such as solution pH, temperature, adsorption time, initial fluoride concentration and co-existing anions were investigated. The adsorption capacity increased with temperature and the kinetics followed a pseudo-second-order rate equation. The enthalpy change (Delta H(0)) and entropy change (DeltaS(0)) was 6.836 kJ mol(-1) and 41.65 J mol(-1)K(-1), which substantiates the endothermic and spontaneous nature of the fluoride adsorption process. Furthermore, the residual concentration of fluoride using Fe(3)O(4)@Al(OH)(3) NPs as adsorbent could reach 0.3 mg L(-1) with an initial concentration of 20 mg L(-1), which met the standard of World Health Organization (WHO) norms for drinking water quality. All of the results suggested that the Fe(3)O(4)@Al(OH)(3) NPs with strong and specific affinity to fluoride could be excellent adsorbents for fluoride contaminated water treatment.