Synthesis of Bacterial Flagella: Chromosomal Synchrony and Flagella Synthesis

Synchronous cultures of Bacillus subtilis 168 M were obtained from light-density spores germinated at 46 C and grown at 37 C. This procedure synchronizes both cell division and chromosome replication. The chromosome synchrony was demonstrated by using transformation to measure changes in marker frequency during the cell cycle. The synthesis of two enzymes and of bacterial flagellar protein was also followed. All of the proteins were found to be synthesized continuously with an abrupt doubling in the rate of synthesis at a specific time in the cell cycle. The time at which the doubling occurred for each enzyme corresponded to the time at which the structural gene for the enzyme was replicated. The doubling of the rate of flagella synthesis corresponded to the time of replication of the hisA1 gene. We conclude that the genetic locus for the factors involved in the rate-limiting steps in flagella synthesis are located on the genetic map near the hisA1 locus.     

Leaf Expansion in the Potato, Solanum tuberosum

The effects of a number of manipulative treatments together with the application of the growth hormones IAA and GA on leaf expansion in the potato, variety Majestic, were investigated. It was found that removal of the apex and its surrounding non-expanded leaves resulted in an increase in both the rate and the extent of expansion of Ihe remaining upper leaves on the system. Application of IAA and GA to decapitated shoots showed that the rate of leaf expansion was decreased by IAA both alone and in combination with GA, whereas it was increased by GA treatment. Further investigations indicated that the response of a leaf to GA treatment was determined by the area and position of the leaf al the time of treatment and also by the number of expanding leaves on the system. It is postulated that this is due, at least in part, to competition for some factor or factors, which could be nutrients, within the system.     

Ferritin H gene polymorphism in idiopathic hemochromatosis

Summary We have analysed karyotypes and DNA from three patients with aniridia (congenital absence of irises) and Wilms' tumour. All three had constitutional deletions from the short arm of chromosome 11. The minimum region of overlap of the deletion involves a small region of band 11p13 presumed to contain the genetic loci responsible for both phenotypic abnormalities. Using cells from these patients, somatic cell hybrids with transformed mouse cells have been prepared. Individual subclones retaining either the deletion-11 chromosome or the normal chromosome 11, in addition to a variety of other human chromosomes, have been identified. The relative position of these breakpoints have been determined and the panel of hybrids has been used to map randomly-isolated 11p13 DNA sequences. The characterisation of these deletions has provided a useful panel of hybrids for random mapping strategies designed to identify the Wilms' and aniridia genes.