Molecular Mechanisms for the Interaction of Regulatory Proteins with Chromosomal DNA

4 Molecular Mechanisms for the Interaction of Regulatory Proteins with Chromosomal DNA 

Regulatory proteins affect the functional status of the nucleus. This can occur through the control of the transcriptional activity of the chromatin. Chromatin and DNA extracted from Rana pipiens embryos at various developmental stages demonstrate (without additional RNA-polymerase) comparatively low transcriptional activity. This activity decreases from the gastrula stage to the stage of actively feeding larvae. The addition of RNA-polymerase to the chromatin preparation leads to increased transcription (Table 30). 

Differences were found in in vitro and in vivo transcriptional activity of chromatin from various parts of the embryo (Flickinger et al., 1965). These differences can be explained by differences in permeability of animal and vegetative halves of the embryo. These differences might also be explained by a reduction of the amount of nuclear RNA-polymerase in the chromatin preparation from late 

Blastula, stage 9 Chromatin of animal halves Chromatin of vegetal halves Gastrula, stage 11 Chromatin of dorsal halves Chromatin of ventral halves Late neurula, stages 15-16 Chromatin of embryonic axis Chromatin of bellies 

Chromatin of bellies minus MnCl2 and RNA polymerase Tailbud, stage 18 Chromatin of embryonic axis Chromatin of bellies 

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