A radioisotope-nondependent high-sensitivity method for measuring the activity of glioblastoma-related O-methylguanine DNA methyltransferase

O⁶-Methylguanine DNA methyltransferase (MGMT) cancels the anticancer effect of temozolomide (drug for glioblastoma), which introduces methylation to DNA. Therefore, developing an MGMT inhibitor is a promising strategy for the treatment of this cancer. For this purpose, a sensitive detection method that does not depend on the conventional radioisotope (RI) method was developed. This was realized by a fluorescence-based method that measured the amount of cleavable restriction sites demethylated by the action of MGMT; this method was enhanced by introducing a polymerase chain reaction (PCR) amplification step. As an assay of enzyme activity, 20-fold higher sensitivity (subnanomolar) was attained compared with our and others’ fluorescence-based approaches.     

Ablation of the Ferroptosis Inhibitor Glutathione Peroxidase 4 in Neurons Results in Rapid Motor Neuron Degeneration and Paralysis

Glutathione peroxidase 4 (GPX4), an antioxidant defense enzyme active in repairing oxidative damage to lipids, is a key inhibitor of ferroptosis, a non-apoptotic form of cell death involving lipid reactive oxygen species. Here we show that GPX4 is essential for motor neuron health and survival in vivo. Conditional ablation of Gpx4 in neurons of adult mice resulted in rapid onset and progression of paralysis and death. Pathological inspection revealed that the paralyzed mice had a dramatic degeneration of motor neurons in the spinal cord but had no overt neuron degeneration in the cerebral cortex. Consistent with the role of GPX4 as a ferroptosis inhibitor, spinal motor neuron degeneration induced by Gpx4 ablation exhibited features of ferroptosis, including no caspase-3 activation, no TUNEL staining, activation of ERKs, and elevated spinal inflammation. Supplementation with vitamin E, another inhibitor of ferroptosis, delayed the onset of paralysis and death induced by Gpx4 ablation. Also, lipid peroxidation and mitochondrial dysfunction appeared to be involved in ferroptosis of motor neurons induced by Gpx4 ablation. Taken together, the dramatic motor neuron degeneration and paralysis induced by Gpx4 ablation suggest that ferroptosis inhibition by GPX4 is essential for motor neuron health and survival in vivo.     

基于PAE编码系统构建的半自然条件下长江江豚行为谱

识别和编制动物行为谱是深入研究动物行为及其与环境复杂关系的基础和前提。本研究于2013年8月至2014年4月以栖息在铜陵淡水豚国家级自然保护区半自然水域的8头长江江豚为研究对象,采用焦点动物取样法和随机动物取样法观察记录了动物行为发生的过程、内容和环境,并以"姿势—动作—环境"(posture-act-environment,PAE)为轴心,以行为的功能为依据,构建了长江江豚的PAE行为谱。共分辨记录了半自然水域长江江豚的8种姿势、33种动作和46种行为,并定性描述了不同行为出现频率与年龄组、性别的关系。该行为谱综合了姿势和环境信息,有助于进一步研究长江江豚的生态与行为、促进长江江豚的保护。     

Carbon nanoparticle for highly sensitive and selective fluorescent detection of mercury(II) ion in aqueous solution

In this article, carbon nanoparticles (CNPs) were used as a novel fluorescent sensing platform for highly sensitive and selective Hg(2+) detection. To the best of our knowledge, this is the first example of CNPs obtained from candle soot used in this type of sensor. The general concept used in this approach is based on that adsorption of the fluorescently labeled single-stranded DNA (ssDNA) probe by CNP via π-π stacking interactions between DNA bases and CNP leads to substantial dye fluorescence quenching; however, in the presence of Hg(2+), T-Hg(2+)-T induced hairpin structure does not adsorb on CNP and thus retains the dye fluorescence. A detection limit as low as 10nM was achieved. The present CNP-based biosensor for Hg(2+) detection exhibits remarkable specificity against other possible metal ions. Furthermore, superior selectivity performance was observed when Hg(2+) detection was carried out in the presence of a large amount of other interference ions. Finally, in order to evaluate its potential practical application, Hg(2+) detection was conducted with the use of lake water other than pure buffer and it is believed that it holds great promise for real sample analysis upon further development.     

Regenerative Surface Plasmon Resonance (SPR) biosensor: real-time measurement of fibrinogen in undiluted human serum using the competitive adsorption of proteins

Epidemiological studies suggest that elevated plasma fibrinogen levels are associated with an increased risk of cardiovascular disorders. Normal fibrinogen level is in the range of 1.5-4.5mg/mL, depending upon both genetic (intrinsic) and environmental (extrinsic) factors. An increase of 0.25mg/mL from the normal level can often be correlated with a high risk of cardiovascular disease. Thus, it is useful to monitor fibrinogen level in serum of a patient for clinical diagnosis. We report a regenerative biosensor that measures real-time fibrinogen levels in undiluted serum. The biosensor uses Surface Plasmon Resonance (SPR), highly sensitive optical technique. The biosensor does not use bio-receptors (i.e., antibodies, enzymes, DNA, etc.) unlike conventional biosensors, and deploys the nature of competitive adsorption of proteins to achieve selective detection of fibrinogen. We measured fibrinogen-spiked serum samples with a concentration of 1.5-4.5 mg/mL, and repeated six measurement trials to obtain statistical distribution of the measurements using the regeneration method of the sensing surface. The SPR biosensor has a sensitivity of 42 mDeg/(mg/mL) for a fibrinogen concentration in the range of 0.5-2.5 mg/mL, whereas it was hard to correlate the measurements to the spiked-fibrinogen samples of above 2.5 mg/mL.