H-1 HISTONE SUBFRACTIONS OF MAMMALIAN TESTES .1. ORGAN SPECIFICITY IN THE RAT

When H1 histones are extracted from chromatin by 5% (w/v) aqueous trichloroacetic acid, the population obtained from rat testis differs from that found in somatic organs in several ways. A readily observable difference is the presence in testicular extracts of a very prominent component that migrates more slowly than other H1 subfractions during electrophoresis in acetic acid/urea-polyacrylamide gels. We present several lines of evidence that indicate that this H1 species is not a unique product of germinal tissue. Rather, it corresponds to a minor H1 component of many other organs, namely, H1a, the first subfraction to elute during chromatography on Bio-Rex 70. Thus, H1a fractions isolated from rat testis and thymus cannot be distinguished by Bio-Rex 70 chromatography or by electrophoresis under two different conditions in which H1a is resolved from all other subfractions: (i) in the presence of acetic acid/urea; and (ii) in the presence of sodium dodecyl sulfate. While H1a evidently plays a special role during male gamete development, and constitutes about 36% of the total H1 histone present in the adult rat testis, it is present in many other organs and represents about 12% of the H1 population in rat thymus. A further distinctive feature of the rat testis H1 population is the lack of readily detectable H1b, the second subfraction to elute from Bio-Rex 70. The functional requirement(s) underlying these changes in the H1 population is not understood. © 1979 American Chemical Society.