Morphogenesis of Escherichia coli

The shape of Escherichia coli is strikingly simple compared to those of higher eukaryotes. In fact, the end result of E. coli morphogenesis is a cylindrical tube with hemispherical caps. It is argued that physical principles affect biological forms. In this view, genes code for products that contribute to the production of suitable structures for physical factors to act upon. After introduction of a physical model, the discussion is focused on the shape-maintaining (peptidoglycan) layer of E. coli. This is followed by a detailed analysis of the structural relationship of the cellular interior to the cytoplasmic membrane. A basic theme of this review is that the transcriptionally active nucleoid and the cytoplasmic translation machinery form a structural continuity with the growing cellular envelope. An attempt has been made to show how this dynamic relationship during the cell cycle affects cell polarity and how it leads to cell division

The self-incompatibility (S) locus in Petunia hybrida is located on chromosome III in a region, syntenic for the Solanaceae

Seven independent transformants were previously shown to carry T-DNA inserts that are genetically linked to the self-incompatibility (S)-locus in Petunia hybrida. These T-DNAs provided reliable targets for fluorescent in situ hybridisation (FISH) localisation. The T-DNA loci were found to be distributed over the entire long arm of chromosome ill. The most tightly linked T-DNA loci were located in a subcentromeric position. Independent confirmation of this assignment of the S-locus to chromosome III was obtained by RFLP analysis of a cDNA marker linked to the S-locus of potato (CP100). Tight linkage was found between CP100 and a peroxidase isozyme locus previously mapped to chromosome ill. The co-localisation of CP100, peroxidase and the S-locus in petunia reveals synteny around the S-locus between four members of the Solanaceae family. The implications of a subcentromeric localisation of the S-locus are discussed in relation to chromosome fragments associated with self-compatible mutants