Histone H1 during germination of pea seeds: an analysis by electrophoretic and immunofluorimetric methods.

Histone H1 has sometimes been reported to undergo quantitative and/or qualitative changes during germination of seeds, but the overall picture on this topic is far from clear. A re-examination of this problem seemed therefore of interest. The H1 content from root tips of ungerminated pea embryos (with nuclei in a completely quiescent state) have been compared with that of seedlings germinated for 48 and 96 h (with nuclei actively involved in transcription and replication). As well as conventional analysis by gel electrophoresis, which seemed to indicate a striking selective decrease of H1 content as germination proceeded, a completely different approach was used: biparametric analysis with flow cytometry, utilizing the indirect immunofluorescence of nuclei previously treated with a monospecific polyclonal antibody raised against pea H1. This proved to be a powerful approach and the results ruled out the possibility of a true depletion of H1 during germination events. Data from SDS electrophoresis of whole nuclear proteins and Northern blot analysis of the H1b cDNA during maturation and germination of pea seeds supported this conclusion.