Biography
Biography: Sunil Palchaudhuri
Abstract
Professor J Lederberg’s F plasmid is evolved in his laboratory strain of E. coli K-12 in 1952. In 1960 antibiotic resistance crisis is reported in a renowned hospital in Tokyo. Ampicillin is not helping the patients with Shigellosis. Extensive research showed that presence of self-transmissible antiobiotic resistance plasmid R in S. flexnerii is responsible for such crisis. Question arises, where does this R plasmid come from (R100, R6-5, R1)? Comparison between R6-5 with Dr. Lederberg’s E. coli K-12 fertility factor F may provide an answer. These two plasmids are self-transmissble and they differ only by 9 base pairs in the repA region containing dnaA gene which is directly involved in initiation of DNA replication. Above all, F plasmid carries two types of mobile DNA elements (Insertion sequences or IS elements IS2, IS3 and transposon Tn1000). The Type II F-prime KLF5 carrying E. coli K12 chromosomal operons is formed by a non-homologous recombination via Tn1000 (gamma-delta). Professor W. K. Maas and his associates B Low and Sunil Palchaudhuri have analysed an unstable F-prime factor KLF5 isolated from the unstable Hfr Ra-2. Such instability is therefore inherited but it is not desirable in Eukaryotes. Unfortunately, emergence of new diseases may result from such spread of transposons. In in vitro gene cloning experiments we have already used antibiotic resistance plasmid R6-5 and a cloning vector pBR322, both carrying Tn1000. It is likely that we have already spread Tn1000 globally and therefore we should think of a measure of how to contain this spread.