We recorded the optical intrinsic signal response of squirrel monkey primary somatosensory cortex (SI) to 25 Hz vibrotactile ("flutter") stimulation applied independently to the thenar eminence on each hand and also to bilateral (simultaneous) stimulation of both thenars. The following observations were obtained in every subject (n = 5). (1) Ipsilateral stimulation was accompanied by an increas...

UV absorbance measurements in microplates became possible only five years ago when Molecular Devices (Sunnyvale, CA, USA) introduced the SPECTRAmax 250, the first UV-Visible microplate spectrophotometer. Microplates have since become very popular for making UV measurements of DNA, RNA and protein concentrations because of their higher throughput compared to traditional cuvettes. Despite their ...

A new ascorbate-induced chloroplast absorbance change which has the characteristics of a carotenoid shift is described. The absorbance change was light-dependent at pH 7 but not at pH 5. The difference spectra for the light and dark changes were similar, showing a large absorbance peak at 505 nanometers, smaller peaks near 468 and 437 nanometers, and a sharp valley around 483 nanometers. The ab...