ZINC-DEFICIENCY IN RAT DOES NOT ALTER THE MAJOR HISTONE PATTERNS IN LIVER NUCLEI

Zinc deficiency exerts many effects on DNA structure, metabolism and f unction. Others have observed that in the single-celled Euglena gracil is, zinc deficiency causes the distinctive appearance of a class of 3- 5-kilodalton (kDa) polypeptides. The major histones, excepting H4, are released from chromatin of zinc deficient Euglena only when these 3-5 -kDa polypeptides are removed. The purpose of this study was to determ ine whether zinc deficiency in rat is associated with a similar class of nuclear polypeptides and the accompanying increased affinity of the major histones to chromatin. Proteins were extracted from purified li ver nuclei by two methods, 0.25 M hydrochloric acid (HCl) or 5% perchl oric acid (PCA). There was no evidence of a class of 3-5-kDa polypepti des from nuclei of zinc deficient rats. There was also no qualitative change in the major histones. Although there were significant decrease s in the amount of HCl and PCA-extracted proteins (P<0.0001) from zinc -deficient liver nuclei, the differences are eliminated when DNA conte nt is taken into account.