IMPROVEMENT OF TECHNIQUE TO MINIMIZE NON-SPECIFIC ABSORPTION IN MICROSPECTROPHOTOMETRIC MEASUREMENT OF NUCLEAR DNA

Abstract

In absorption cytophotometry, instrumental and optic errors are important. Although most of them have been studied extensively and practically solved, the so far unrecognised problem of non-specific loss of light arises in the measurements on biological materials especially on sections of brain tissues. Unstained objects scatter significant amount of light at various wave-lengths. Cytophotometry on DNA content of the cells in Feulgen stained material is affected significantly by this factor. In Feulgen stained materials, such non-specific light loss of the light is detected by scanning with a light spot at wave-length of 450 or 650mμ. In sections of rat cerebellum, the non-specific light loss amounts to a considerable quantity and is difficult to eliminate. By preparing smears directly from the brain tissue, the authors succeeded in minimizing the effect of the non-specific light loss. Nuclei of Purkinje cells and inner granule cells in the smears are studied for their Feulgen dye content by total scanning method. The data obtained on smeared cells clearly indicate that both types of cells are in the same class of DNA content.