Disrupted Cacna1c gene expression perturbs spontaneous Ca2+ activity causing abnormal brain development and increased anxiety.

The L-type voltage-gated Ca2+ channel gene CACNA1C is a risk gene for various psychiatric conditions, including schizophrenia and bipolar disorder. However, the cellular mechanism by which CACNA1C contributes to psychiatric disorders has not been elucidated. Here, we report that the embryonic deletion of Cacna1c in neurons destined for the cerebral cortex using an Emx1-Cre strategy disturbs spontaneous Ca2+ activity and causes abnormal brain development and anxiety. By combining computational modeling with electrophysiological membrane potential manipulation, we found that neural network activity was driven by intrinsic spontaneous Ca2+ activity in distinct progenitor cells expressing marginally increased levels of voltage-gated Ca2+ channels. MRI examination of the Cacna1c knockout mouse brains revealed volumetric differences in the neocortex, hippocampus, and periaqueductal gray. These results suggest that Cacna1c acts as a molecular switch and that its disruption during embryogenesis can perturb Ca2+ handling and neural development, which may increase susceptibility to psychiatric disease.

Reusable amperometric biosensor for measuring protein tyrosine kinase activity.

This work presents a simple, low-cost and reusable label-free method for detecting protein tyrosine kinase activity using a tyrosinase-based amperometric biosensor (tyrosine kinase biosensor). This method is based on the observation that phosphorylation can block the tyrosinase-catalyzed oxidation of tyrosine or tyrosyl residue in peptides. Therefore, the activity of p60c-src protein tyrosine kinase (Src) on the developed tyrosine kinase biosensor could be quickly determined when its specific peptide substrate, p60c-src substrate I, was used. The tyrosine kinase biosensor was highly sensitive to the activity of Src with a linear dynamic range of 1.9-237.6 U/mL and the lowest detection limit of 0.23 U/mL. Interestingly, the tyrosine kinase activity can be measured using the developed tyrosine kinase biosensor repetitively without regeneration. The inhibitory effect of various kinase inhibitors on the Src activity could be determined on the tyrosine kinase biosensor. Src-specific inhibitors, PP2 and Src inhibitor I, effectively suppressed Src activity, whereas PD153035, an inhibitor of the epidermal growth factor receptor, was ineffective. Staurosporine, a universal kinase inhibitor, inhibited Src activity in an ATP concentration-dependent manner. These results suggests that the activities of tyrosine kinases and their behaviors toward various reagents can be effectively measured using the developed tyrosine kinase biosensor.

Fabrication of a carbon fiber paper as the electrode and its application toward developing a sensitive unmediated amperometric biosensor.

Carbon fiber paper (CFP), a material frequently used as the diffusion layer in fuel cells, was found recently to exhibit a potential as an electrode for the development of sensitive, unmediated biosensors. After nitrogen plasma treatment, the CFP exhibited a quasi-reversible behavior to the redox couple (e.g., ferricyanide) with an electron transfer rate constant of 7.2 × 10(-3)cms(-1). This rate constant is approximately double that of a Pt-electrode and is much higher than that of many carbon-based electrodes. The unmediated CFP-based tyrosinase biosensor fabricated for this study exhibited an optimal working potential and operating pH value of -0.2V and 6.5, respectively. Compared to other unmediated tyrosinase biosensors, the CFP-based tyrosinase biosensor offers a high sensitivity for the monitoring of phenolic compounds (17.8, 7.1, 5.2 and 3.7 µA µM(-1)cm(-2) for catechol, phenol, bisphenol and 3-aminophenol, respectively). The lowest detection limit for catechol, phenol, bisphenol and 3-aminophenol was 2, 5, 5 and 12 nM, respectively. Furthermore, this biosensor exhibited a good repeatability, a fast response time (around 10s), and a wide linear dynamic range of detection for phenolic compounds.