Papers
The dynamic range of Cameleon (calcium sensor made of YFP-CaM-M13-CFP) was enhanced up to 6 times by replacing YFP to cpYFP. They tried several different cpYFP to optimize the FRET changes between CFP and YFP, and only one of them showed a great enhancement of the sensitivity for some reason. This could be a general aproach to enhance sensitivity of FRET-based sensors.
Backpropagation of action potential is important for plasticity. The backpropagation is attenuated and mostly passive at distal parts of dendrites further than 250um. They measured backpropagation of pilocarpine-treated rats, an animal model for epilepsy, finding that backpropagation is significantly enhanced compared to sham-rats. This is partly caused by phosphorylation of A-type K+ channels, which is donwstream of ERK and PKC. Blocking of ERK or general phosphorylation reduced the enhancement of backpropagation.
Combination of activation of AMPA and mGluR induce Ca-dependent glutamate release from astrocyte in astrocyte culture and slices. The process involves activation of the arachidonate cascade. They use enzymatic assay to measure the amount of glutamate released. In slice experiments, neuronal exocytosis was blocked by TeNT.
Imunogold shows cellubrevin (v-SNARE protein) is espressed in astrocyte vesicles and colocalized with VGLUT (vesicular glutamate transpoter). Excocytotic events of acridine-orange (AO) filled, GFP-VGLUT positive vesicles are visualized by total internal reflection microscopy. AO is quenched in the acidic environment such as in vesicles. Once vesicles fuse, AO is released, producing a flush, and decay quickly due to the diffusion. Using this technique, quick releases of vesicles by mGluR activation were shown. This exocytosis releases glutamate as evident from the [Ca2+] elevation in a 'glutamate-sniffing' insulinoma-1 cell close to an astrocyte.
