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Abstract
The phenomenon whereby Salmonella cells produce curly flagella in media containing p-fluorophenylalanine was used to investigate the polarity of flagellar growth. Salmonella typhimurium lt2 in logarithmic growth in broth was transferred to minimal medium or saline, or their flagella shortened by mechanical breaking. Then, after 2 to 3 hr at 37° in a medium containing p-fluorophenylalanine the distributions of number, length and shape of their flagella were observed. Curly waves appeared at the distal portions of flagella. The growth rate of a flagellum decreased as its length increased, reaching zero at approximately five normal wave-numbers (about 15 μ). The growth rate of flagella shortened by mechanical breaking was not less than that of intact ones of similar length. The decline is attributed to decrease in transport efficiency with increase in length rather than to ageing of the flagellum-forming apparatus.
A normal flagellar strain and a curly mutant strain of Salmonella abortusequi were grown together in broth. Numbers of both types of rods and flagella increased to 1·5-fold in 3 hr. At this stage, neither heteromorphous rods nor single flagella having both normal and curly waves were detected. Hence, flagellin molecules reach the top of a growing flagellum without being excreted into the culture medium.
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