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A quartz crystal microbalance with dissipation monitoring (QCM-D) sensor was developed for highly sensitive and specific detection of mercury(ii) ions (Hg2) with a tunable dynamic range, using oligonucleotide-functionalized gold nanoparticles (GNPs) for both frequency and dissipation amplification. The fabrication of the sensor employed a ‘sandwich-type’ strategy, and formation of T–Hg2–T structures in linker DNA reduced the hybridization of the GNPs-tagged DNA on the gold electrode, which could be used as the molecular switch for Hg2뇩. This QCM-D mercury sensor showed a linear response of 10–200 nM, with detection limits of 4 nM and 7 nM for frequency and dissipation measurements, respectively. Moreover, the dynamic range of the sensor could be tuned by simply altering the concentration of linker DNA without designing new sensors in the cases where detection of Hg2 different levels is required. This sensor afforded excellent selectivity toward Hg2犉ꥪ랝 with other potential coexisting metal ions. The feasibility of the sensor was demonstrated by analyzing Hg2+spiked tap- and lake-water samples with satisfactory recoveries. The proposed approach extended the application of the QCM-D system in metal ions sensing, and could be adopted for the detection of other analytes when complemented with the use of functional DNA structures. [ABSTRACT FROM AUTHOR]

Abstract: We unexpectedly discover that there are much lower GC3 and GC-content and higher Gibbs free energy on editing exons than other exons in the Drosophila synaptotagmin I transcripts, which was further, confirmed statistically by others 47 experimentally-validated samples. Sequence alignment, Ks and Ka/Ks assays suggest that rapidly ascending purifying selection occur in editing exons which constrains nucleotide divergency. The presence of specific molecular characteristics such as lower GC-content in editing exons imply an unexpected requirement and are likely to direct RNA editing occurrence. Thus, relations between molecular characteristics of DNA, RNA editing and purifying selection might be present. [Copyright &y& Elsevier]