The heat shock proteins (Hsps) play a positive role in lifespan determination, and histone acetylation has been shown to be involved in transcription of hsp genes in Drosophila. To further determine if hsp22 and hsp70 expression is correlated with lifespan, and if histone acetylation participates in this process, RNA levels for hsp22 and hsp70 were analyzed throughout the lifespan in the long-lived and short-lived iso-female lines. The results showed that hsp22 and hsp70 RNA levels were higher in long-lived line than in short-lived line and that the longlived flies responded more rapidly to heat but were more tolerant to high temperature. Moreover, we investigated the influences of histone acetylation modification on longevity and on hsp gene expression by using histone deacetylase (HDAC) inhibitors TSA and BuA. The results demonstrated that both inhibitors were able to extend the lifespan and promote hsp22 and hsp70 expression. However, the optimal concentrations of these inhibitors, and probably the mechanisms of their actions, vary with the genetic background. In addition, we showed that HDAC inhibitors caused the hyperacetylation of core histone H3, implicating the involvement of chromatin modulation in hsp gene transcription. These data suggested a close correlation among histone acetylation, hsp gene expression and longevity in D. melanogaster.

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Tau protein plays a crucial role in the pathogenesis of Alzheimer's disease (AD). However, the assay to detect low concentrations of tau protein is a great challenge for the early diagnosis of AD. We will outline a novel aptamer-antibody sandwich assay based on an electrochemical biosensor for the detection of tau-381 in human serum. To improve the detection sensitivity, the aptamer-antibody sandwich assay for the detection of tau-381 was developed by using a tau antibody (anti-tau) and an aptamer specific to tau-381 as the recognition element and cysteamine-stabilized gold nanoparticles (AuNPs) for signal amplification. Differential pulse voltammetry (DPV) was employed to record the signal response of tau-381 with different concentrations. The tau-381 concentration ranged from 0.5 pM to 100 pM. The responses of DPV measurements showed excellent results in this dynamic range. This simple, rapid, highly sensitive and specific assay gave a low limit of detection (LOD) of 0.42 pM for tau-381. The feasibility and reliability of the assay were verified by testing tau-381 in human serum from patients with AD. Thus, this method could prove valuable in diagnosing AD within the early stages of the disease.