Magnesium malate

The high-salt/hypotonic fractionation method for nuclear protein extraction is based on the differential solubility of cellular components. Cytoplasmic proteins are extracted first using a hypotonic buffer that causes cell swelling and membrane rupture, followed by centrifugation to separate the cytoplasmic supernatant from the nuclear pellet. The nuclear pellet is then subjected to high-salt extraction (e. g. , 0. 4 M (NH4)2SO4 or 1 M NaCl) to solubilize tightly bound nuclear matrix proteins, including transcription factors, histones, and structural proteins associated with chromatin and the nuclear scaffold. This approach allows for the isolation of both soluble cytoplasmic proteins and salt-resistant nuclear proteins while minimizing cross-contamination.

Primary dorsal root ganglion sensory neuron culture isolates DRG neuronal somata from rodent or human ganglia, dissociates tissue enzymatically and mechanically, and maintains post-mitotic sensory neurons in vitro for readouts such as neurite outgrowth, immunocytochemical marker expression, calcium imaging, electrophysiology, RNA/protein analysis, or neuropeptide release assays. The method reflects peripheral sensory neuron biology because DRG neurons are primary sensory neurons whose cell bodies reside in dorsal root ganglia and whose cultured dissociated cells can retain neuronal morphology, sensory-neuron marker expression, and stimulus-responsive properties depending on the downstream assay.

The following protocol uses the MTT colorimetric assay as a classic literature-established method for assessing cell viability/metabolic activity in cultured mammalian cells. MTT[3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] is reduced by metabolically active cells to a colored formazan product; the amount of formazan is quantified spectrophotometrically and provides an indirect measure of metabolically active viable cells. Importantly, MTT reduction reflects cellular oxidoreductase/metabolic activity rather than an absolute direct count of living cells, so changes in cellular metabolism can alter the signal independently of cell number.