Detection of hydrogen sulfide in water samples with 2-(4-hydroxyphenyl)-4,5-di(2-pyridyl)imidazole-copper(II) complex using environmentally green microplate fluorescence assay method.

Hydrogen sulfide (H2S) is a colorless toxic gas which can be found as HS- in rivers and waste waters especially in the occupational susceptible environment. Herein we synthesized a lophine analogue, 2-(4-hydroxyphenyl)-4,5-di(2-pyridyl)imidazole (HPI), which fluoresces at 410 nm after excitation at 280 nm. HPI has an imidazole ring and a pyridine ring which are capable of forming coordinate bonds with copper (Cu(II)) that cause quenching of HPI fluorescence. We found that HS- can selectively liberate HPI from the complex via formation of CuS, thus, HPI regains its fluorescence properties. Interestingly, the probe was proved to be regenerable. This reaction was used for the development of a fluorescence microplate assay for the determination of HS- in environmental samples. The method was applied to river water samples and was able to detect HS- in concentrations down to 5 ppb with acceptable accuracy (90.3-103.0%) and good precision (%RSD ≤ 4.1). The method showed many advantages over the previously reported ones including instantaneous reaction, simple probe synthesis, high-throughput, high selectivity toward hydrogen sulfide over other ions and sulfur or thiol containing compounds and at last, it complies with the green chemistry rules through using a regenerable probe, aqueous solvents, and miniaturized measurement system.

αvß5 integrin mediates the effect of vitronectin on the initial stage of differentiation in mouse cerebellar granule cell precursors.

Vitronectin (VN), one of the extracellular matrix proteins, controls the maturation of cerebellar granule cells (CGCs) through the promotion of the initial differentiation stage progress. However, the receptors of VN in the initial differentiation stage of CGC precursors (CGCPs) have not been clarified. In this study, we characterized the receptor candidates for VN in CGCPs. First, we confirmed that αvß3 and αvß5 integrins, which are receptor candidates for VN, were co-localized with VN in the developing cerebellum and primary cultured CGCPs. Next, the knockdown (KD) of αv, ß3, and ß5 integrins with small interference RNA (siRNA) for each integrin reduced the ratio of Tuj1, a final differentiation marker, -positive CGCPs. We further studied whether αvß3 and αvß5 integrins control the initial differentiation stage. The KD of αv and ß5, but not ß3, integrins significantly increased the ratio of transient axonal glycoprotein 1 (TAG1), an initial differentiation marker, -positive CGCPs, whereas the KD of αv and ß3 integrins, not ß5 integrin, stimulated the proliferation of CGCPs. Overexpression of ß5 integrin stimulated the progress of the initial differentiation stage as well. To confirm the interaction between αvß5 integrin and VN, VN was added to ß5 integrin-KD CGCPs. The promotion of the progress of initial differentiation by VN was abrogated by ß5 integrin KD using small hairpin RNA (shRNA). Taken together, our results indicated that αvß5 integrin, as the very receptor of VN, is responsible for the progress of the initial differentiation stage in mouse CGCPs.

Molecular characterization of genes encoding isoamylase-type debranching enzyme in tuberous root of sweet potato, Ipomoea batatas (L.) Lam.

Isoamylase (ISA) is a starch debranching enzyme that removes α-1,6-glucosidic linkages in α-polyglucans such as amylopectin. From previous studies, plant isoamylases have been shown to play a crucial role in amylopectin biosynthesis; however, little is known about their function in storage root tissues of plants such as cassava, yam and sweet potato. In this study, we isolated cDNA clones and characterized the cDNA nucleotide sequences of three genes (IbISA1, IbISA2, IbISA3) encoding isoamylase from sweet potato (Ipomoea batatas (L.) cv. White Star). Deduced amino acid sequences of the three isolated IbISAs have the specific regions that are highly conserved among the α-amylase family members. The product of IbISA2 is predicted to be enzymatically inactive, like other plant ISA2s, due to replacement of amino acid residues that are important for hydrolytic reaction. qRT-PCR analysis demonstrated that expression of IbISA2 was higher than that of the other two IbISAs (IbISA1 and IbISA3) in tuberous root at 109 days after planting, at which stage of tuberous root was at which stage tuberous roots were almost fully developed almost developed. This expression pattern observed in our experiments was different from that in other sink organs, such as seeds (endosperms), indicating that orchestration of ISA gene expression may depend on the differences in sink organ type between tuberous roots and seeds. The molecular characterization of three IbISA genes and their expression analysis in this study will contribute to further studies on starch biosynthesis in sweet potato, especially in storage root.

Determination of the standard entropy changes of ion transfer for 1-alkylpyridinium ions by thermal modulation voltammetry with laser heating at a water/1,2-dichloroethane interface.

When laser light impinges upon a liquid-liquid interface between an optically transparent aqueous and opaque organic phase from the aqueous to organic phase, the temperature at the interface and the interfacial region rises. Using this rise in temperature, we have proposed and developed thermal modulation voltammetry at an interface between two immiscible electrolyte solutions (TMV-ITIES) and have determined the standard entropy changes of ion transfer, ΔS(tr)(°,O→W). In this work, we have determined ΔS(tr)(°,O→W) for four 1-alkylpridinium ions, namely 1-methylpyridinium ion (MePy(+)), 1-ethylpyridinium ion (EtPy(+)), 1-propylpyridinium ion (PrPy(+)), and 1-buthylpyridinium ion (BuPy(+)) by TMV-ITIES. As a result, we obtained the ΔS(tr)(°,O→W) values of 108.0 ± 0.5 (n = 3), 75.8 ± 4.4, 55.6 ± 1.2, and 42.7 ± 0.9 J K(-1) mol(-1) for MePy(+), EtPy(+), PrPy(+), and BuPy(+), respectively. From these values of ΔS(tr)(°,O→W), we have suggested that MePy(+), EtPy(+), and PrPy(+) are classified as water structure-breaking ions and BuPy(+) as a weak water structure-making ion. Further, we discuss the relationship between the standard free energy change, ΔG(tr)(°,O→W), and ΔS(tr)(°,O→W) of ion transfer for 1-alkylpridinium ions and tetraalkylammonium ions.