A new rhodamine‐based fluorescent chemodosimeter for mercuric ions in water media

A new rhodamine–ethylenediamine–nitrothiourea conjugate (RT) was synthesized and its sensing property as a fluorescent chemodosimeter toward metal ions was explored in water media. Analytical results from absorption and fluorescence spectra revealed that the addition of Hg²⁺ ions to the aqueous solution of the chemodosimeter RT caused a distinct fluorescence OFF–ON response with a remarkable visual color change from colorless to pink; however, no clear spectral and color changes were observed from other metal ions including: Zn²⁺, Cu²⁺, Cd²⁺, Pb²⁺, Ag⁺, Fe²⁺, Cr³⁺, Co³⁺, Ni²⁺, Ca²⁺, Mg²⁺, K⁺ and Na⁺. The sensing results and the molecular structure suggested that a Hg²⁺‐induced a desulfurization reaction and cyclic guanylation of the thiourea moiety followed by ring‐opening of the rhodamine spirolactam in RT are responsible for a distinct fluorescence turn‐on signal, indicating that RT is a remarkably sensitive and selective chemodosimeter for Hg²⁺ ions in aqueous solution. Hg²⁺ within a concentration range from 0.1 to 25 μM can be determined using RT as a chemodosimeter and a detection limit of 0.04 μM is achieved. Copyright © 2014 John Wiley & Sons, Ltd.     

Glucocorticoids Suppress Renal Cell Carcinoma Progression by Enhancing Na,K-ATPase Beta-1 Subunit Expression

Glucocorticoids are commonly used as palliative or chemotherapeutic clinical agents for treatment of a variety of cancers. Although steroid treatment is beneficial, the mechanisms by which steroids improve outcome in cancer patients are not well understood. Na,K-ATPase beta-subunit isoform 1 (NaK-β₁) is a cell-cell adhesion molecule, and its expression is down-regulated in cancer cells undergoing epithelial-to mesenchymal-transition (EMT), a key event associated with cancer progression to metastatic disease. In this study, we performed high-throughput screening to identify small molecules that could up-regulate NaK-β₁ expression in cancer cells. Compounds related to the glucocorticoids were identified as drug candidates enhancing NaK-β₁ expression. Of these compounds, triamcinolone, dexamethasone, and fluorometholone were validated to increase NaK-β₁ expression at the cell surface, enhance cell-cell adhesion, attenuate motility and invasiveness and induce mesenchymal to epithelial like transition of renal cell carcinoma (RCC) cells in vitro. Treatment of NaK-β₁ knockdown cells with these drug candidates confirmed that these compounds mediate their effects through up-regulating NaK-β₁. Furthermore, we demonstrated that these compounds attenuate tumor growth in subcutaneous RCC xenografts and reduce local invasiveness in orthotopically-implanted tumors. Our results strongly indicate that the addition of glucocorticoids in the treatment of RCC may improve outcome for RCC patients by augmenting NaK-β₁ cell-cell adhesion function.     

Development of Neoseiulus womersleyi (Schicha) and Euseius ovalis (Evans) feeding on four tetranychid mites (Acari: Phytoseiidae,Tetranychidae) and pollen

The development of the predatory mites, Neoseiulus womersleyi (Schicha) and Euseius ovalis (Evans), feeding on four tetranychid mites (Tetranychus urticae, Tetranychus kanzawai, Oligonychus mangiferus, Panonychus citri), maize pollen or Chinese loofah pollen was studied at 25 °C. Immature stages of N. womersleyi feeding on T. urticae and T. kanzawai had shorter developmental duration (4.71 and 5.02 days for females, 4.77 and 5.19 days for males, respectively) than those feeding on other food sources. Immature stages of E. ovalis females feeding on O. mangiferus and T. urticae developed in 4.99 and 5.13 days, respectively, the shortest developmental duration measured. Immature stages of E. ovalis males feeding on O. mangiferus and T. urticae developed in 5.12 and 5.37 days, respectively. The longevity of N. womersleyi males (13.31 to 14.51 days) and females (17.67 to 21.81 days) feeding on T. urticae, T. kanzawai or maize pollen was longer than the longevity of N. womersleyi feeding on O. mangiferus, P. citri or loofah pollen. E. ovalis males (12.91 to 16.74 days) and females (16.24 to 23.77 days) feeding on O. mangiferus, T. urticae or maize pollen lived longer than E. ovalis males and females feeding on T. kanzawai, P. citri or loofah pollen.     

Conformations generated during turnover of the Azotobacter vinelandii nitrogenase MoFe protein and their relationship to physiological function

Various S=3/2 EPR signals elicited from wild-type and variant Azotobacter vinelandii nitrogenase MoFe proteins appear to reflect different conformations assumed by the FeMo-cofactor with different protonation states. To determine whether these presumed changes in protonation and conformation reflect catalytic capacity, the responses (particularly to changes in electron flux) of the alphaH195Q, alphaH195N, and alphaQ191K variant MoFe proteins (where His at position 195 in the alpha subunit is replaced by Gln/Asn or Gln at position alpha-191 by Lys), which have strikingly different substrate-reduction properties, were studied by stopped-flow or rapid-freeze techniques. Rapid-freeze EPR at low electron flux (at 3-fold molar excess of wild-type Fe protein) elicited two transient FeMo-cofactor-based EPR signals within 1 s of initiating turnover under N(2) with the alphaH195Q and alphaH195N variants, but not with the alphaQ191K variant. No EPR signals attributable to P cluster oxidation were observed for any of the variants under these conditions. Furthermore, during turnover at low electron flux with the wild-type, alphaH195Q or alphaH195N MoFe protein, the longer-time 430-nm absorbance increase, which likely reflects P cluster oxidation, was also not observed (by stopped-flow spectrophotometry); it did, however, occur for all three MoFe proteins under higher electron flux. No 430-nm absorbance increase occurred with the alphaQ191K variant, not even at higher electron flux. This putative lack of involvement of the P cluster in electron transfer at low electron flux was confirmed by rapid-freeze (57)Fe M?ssbauer spectroscopy, which clearly showed FeMo-factor reduction without P cluster oxidation. Because the wild-type, alphaH195Q and alphaH195N MoFe proteins can bind N(2), but alphaQ195K cannot, these results suggest that P cluster oxidation occurs only under high electron flux as required for N(2) reduction.