Formation of biogenic tellurium nanorods in unicellular green alga Chlamydomonas reinhardtii.

Tellurium (Te) is an industrially useful element but causes environmental contamination. The formation of biogenic Te nanorods (Te-BgNRs) in plants is one of the Te detoxification pathways associated with the phytoremediation of Te because Te-BgNRs contain low-toxicity Te at high densities. In this study, we investigated the mechanism of Te-BgNR formation in a common unicellular green alga, Chlamydomonas reinhardtii, on the basis of elemental analysis by inductively coupled plasma mass spectrometry (ICP-MS). After exposure to 1000 µM sodium tellurate (Na2TeO4) for 2 weeks, the alga accumulated 65.2 fg of Te per cell, and 55.8% of which was present in an insoluble form. Electron microscopic observations revealed that the insoluble Te was rod-shaped elemental Te, i.e. Te-BgNRs, and had a highly crystalline nanostructure. We determined the Te contents in Te-BgNRs by single-particle ICP-MS analysis and found that these nanorods were formed at tellurate exposure concentrations of 100 to 1000 µM. In contrast, soluble Te compounds were found in algal cells even at exposure concentrations lower than 100 µM. These findings suggest that the algal cells initially metabolized tellurate to form soluble Te compounds, and excess tellurate that could not be metabolized was then transformed to Te-BgNRs, which are less toxic than tellurate. Our findings provide a novel approach to Te remediation through the formation of BgNRs in C. reinhardtii.

Elucidation of tellurium biogenic nanoparticles in garlic, Allium sativum, by inductively coupled plasma-mass spectrometry.

BACKGROUND: Biosynthesis of Te nanoparticles may occur in higher plants exposed to Te, as reported on microorganisms. However, unambiguous observations of the biogenic nanoparticles (BgNPs) of Te in plants are lacking. Hence, in this study, we investigated the formation of insoluble BgNPs of Te in garlic (Allium sativum) as a model plant. METHOD: We performed elemental analysis based on inductively coupled plasma-mass spectrometry (ICP-MS) technique, and obtained Te concentration and distribution in various parts of garlic. In addition, insoluble Te particles were detected by fast time-resolved ICP-MS. Direct observation of the insoluble Te particle was also conducted by scanning electron microscope (SEM) and transmission electron microscope (TEM). RESULTS: A part of the roots and clove from Te-exposed garlic showed black coloration. Te concentrations in the black-colored parts were significantly increased compared with the non-colored parts. Transient signals of Te unique to nanoparticles were detected from the insoluble fractions of the black-colored parts. Finally, rod-shaped biogenic Te nanoparticles consisting of highly crystalline elemental Te was observed by SEM and TEM. CONCLUSION: Our data provide new insights to the metabolic pathway of Te in higher plants for the formation of insoluble biogenic nanoparticles, which is extremely important for the detoxification of Te.

Quantitative Elemental Analysis of a Single Cell by Using Inductively Coupled Plasma-Mass Spectrometry in Fast Time-Resolved Analysis Mode.

The elemental composition of a single yeast, green alga, or red blood cell (RBC) was precisely determined by using inductively coupled plasma-mass spectrometry (ICP-MS) operating in fast time-resolved analysis (TRA) mode. The technique is known as single-cell (SC)-ICP-MS. Phosphorus, sulfur, magnesium, zinc, and iron were detected in the three types of cell. The elemental composition of yeast and green alga obtained by SC-ICP-MS was consistent with results obtained from conventional ICP-MS measurements following acid digestion of the cells. Slight differences were found in the measured values between SC-ICP-MS and the conventional ICP-MS results for RBC. However, the SC-ICP-MS results for S and Fe in RBC were closer to the estimated values for these elements that were calculated from the level of hemoglobin in RBCs. The data suggest that SC-ICP-MS is suitable for the analysis of various cell types, namely, fungus, plant, and animal cells.

In vitro and in vivo antimalarial activity of puberulic acid and its new analogs, viticolins A-C, produced by Penicillium sp. FKI-4410.

In the course of screening for antimalarial agents, five tropolone compounds were isolated from the culture broth of Penicillium sp. FKI-4410. Two were known compounds, puberulic acid and stipitatic acid. Three were new analogs of puberulic acid, designated viticolins A-C. Among them, puberulic acid exhibited potent antimalarial inhibition, with IC(50) values of 0.01 µg ml(-1) against chloroquine-sensitive and -resistant Plasmodium falciparum strains in vitro. Furthermore, puberulic acid showed weak cytotoxicity against human MRC-5 cells, with an IC(50) value of 57.2 µg ml(-1). The compound also demonstrated a therapeutic effect in vivo, which compared well against the currently used antimalarial drugs, and thus shows promise as a leading candidate for development into a new antimalarial compound.

Validation of "lung age" measured by spirometry and handy electronic FEV1/FEV6 meter in pulmonary diseases.

OBJECTIVE: The concept of "lung age" is thought to be useful for understanding pulmonary function. In this study, we validated "lung age" to detect pulmonary function abnormalities in pulmonary diseases. METHODS: We used both spirometry and an electronic FEV(1)/FEV(6) meter (FEV(6) meter) to perform pulmonary function tests. We evaluated the sensitivity and specificity of FEV(6) and FEV(1)/FEV(6), and calculated "lung age" in Japanese subjects including those with chronic obstructive pulmonary disease (COPD), bronchial asthma (BA), and interstitial lung diseases (ILD). RESULTS: FEV(1) (spirometer) vs. FEV(1) (FEV(6) meter), FVC (spirometer) vs. FEV(6) (FEV(6) meter), and FEV(1)/FVC (spirometer) vs. FEV(1)/FEV(6) (FEV(6) meter) measurements were all significantly and closely correlated. For the difference of "lung age" and "actual age", the area under the receiver operating characteristic curve (ROC-AUC) for detecting obstructive impairment was 0.807 (spirometer) and 0.772 (FEV(6) meter), respectively. The corresponding ROC-AUC for detecting restrictive impairment was 0.891 and 0.836, respectively, and that for detecting both obstructive and restrictive impairment was 0.918 and 0.853, respectively. For detection of both obstructive and restrictive impairment, the difference of the "lung age" and "actual age" cut-off value, corresponding to the greatest sum of sensitivity and specificity, was 18.3 years (spirometer) and 19.8 years (FEV(6) meter), respectively. The sensitivity was 0.783 (spirometer) and 0.801 (FEV(6) meter), and the specificity was 0.895 (spirometer) and 0.790 (FEV(6) meter), respectively. CONCLUSION: "Lung age" can provide an easy interpretation of the results, and can detect pulmonary function abnormalities in pulmonary diseases.