This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Racela, A. Articles by Svoboda, D. Search for Related Content PubMed PubMed Citation Articles by Racela, A. Articles by Svoboda, D.

Ultrastructural Nuclear Changes Due to Tannic Acid

Department of Pathology and Oncology, University of Kansas Medical Center, Kansas City, Kansas 66103

In rat liver, tannic acid causes an early and promptly reversible form of nucleolar macrosegregation which differs from other forms of nucleolar segregation or capping. A small nucleolus with condensation of compact ribonucleoprotein granules into one or more dark zones is characteristic. These zones are surrounded by a light area made up of a mixture of ribonucleoprotein granules and fibrils. In later stages the zones contain predominantly fibrils. The macrosegregation due to tannic acid is not related to significant decrease in RNA and proteins in the nuclear or cytoplasmic fractions. In this respect, the biochemical effects of tannic acid differ from certain other hepatocarcinogens, notably aflatoxin and lasiocarpine, which also cause early nucleolar abnormalities. In light of recent reports, nucleolar segregation or capping appears to be a morphologic expression of biochemical alterations in nuclear function, particularly the binding with DNA and inhibition of its template activity. The precise biochemical action of tannic acid on nucleoproteins is not known, and similarity of its action to that of other capping agents is not substantiated by the preliminary biochemical observations in the present study.

Received 1/ 6/67. Accepted 5/12/67.