| Description |
"This is precisely what Herman Denis did during a stay a few years later at Jean Brachet's lab at the LlGBin Naples. He showed that RNAsynthesized by an interspecific sea urchin hybrid blocked at the gastrula stage is preponderantly paternal, despite the preferential elimination of paternal chromosomes during egg cleavage. With elegant saturation and competition experiments using molecular hybridization on filt~rs. he explained the paradox by the existence of two classes of genes that become active at the onset of gastrulation, The first and most abundant class of genes, destined to be expressed at all stages of development, are normally subject to negative control, which a foreign cytoplasm cannot exert. The second group of genes. which are functional only during the early developmental stages. fail. on the other hand. to be activated in the same foreign cytoplasm. These outstanding results already underline the full importance of the activation and repression of genes exerting specific control over the stages of morphogenesis. They were published in 1969 and 1970, in three papers signed H. Denis and J. Brachet that received much attention." Jean Brachet and his School by HENRI ALEXANDRE Int. J. Dev Biol. 36: 29-41 (1992) First separate edition. Offprint. Original wrappers.* |
