Previous work of Dr. Shapirio has reinforced the view of bacterial colonies as highly organized, differentiated structures with specific developmental histories. Work with E. coli strains carrying various lac fusion elements has raised detailed questions about the cellular and molecular events involved in pattern formation during colony development. Some of these questions pertaining to patterns of cellular differentiation can be answered by a more detailed microscopic analysis of colony structure using histochemical, immunological and in situ hybridization technologies. Identification of the components of multicellular control systems will be initiated by standard molecular genetic methods (transposon mutagenesis, cloning and testing of known regulatory mutations). Further material for identifying currently unpredictable changes in morphogenetic regulatory systems has become available through the appearance of sectors containing bacteria that display novel hereditary patterns of gene expression, colony development and cell division. The novel phenotypes expressed by these bacteria can be characterized by the same methods that will be applied to normal colonies, and the nature of the hereditary changes in them can be examined by DNA transfer and cloning procedures. Once all these studies have begun to provide a more precise picture of colony structure and its underlying genetic control, it will be possible to begin investigating what happens when many bacterial cells in a multicellular inoculum organize themselves to undergo a regular developmental sequence. %%% Dr. Shapiro has provided some evidence that colony development in bacteria shows some distinct temporal changes in morphology. He proposes that this can be used as a model to obtain information about how multicellular organisms develop and differentiate. His work is unique in this area and could lead to the development of powerful models for the study of differentiation.
