HYDROLYSIS IN FEULGEN AUTORADIOGRAPHY .I. LOSS OF LABEL FROM S-PERIOD NUCLEI AND ITS SUBSEQUENT ASSOCIATION WITH NON-S CHROMATIN

An examination of the effect of acid hydrolysis on grain count and distribution following 3H-thymidine labelling and Feulgen staining was undertaken. It was verified that removal of label from S-period nuclei was initiated well before the point of maximal staining. It was further shown that there was a specific reassociation of displaced label with normally non-S chromatin. This reassociated label reached very high levels at longer periods of hydrolysis, i.e., 15-20 min, but was seen to begin accumulating to significant levels as early as 6-8 min into hydrolysis. It was demonstrated that this reassociation could lead to an apparent increase in labelling index. The implications of the findings and possible future work were discussed. © 1969.