Journal of the Ghana Science Association

Log in or Register to get access to full text downloads.

Remember me or Register

DOWNLOAD FULL TEXT Open Access  DOWNLOAD FULL TEXT Subscription or Fee Access

UV irradiation of Shigella dysenteriae induced the transformation and excision of a presumed integrated lysogenic prophage Shd-4L10 into a lytic phase

FK Rodrigues, G Armah, J Fobil, M Steiner-Asiedu, J Efavi, B Addy


Repeated exposures of Shigella dysenteriae strain A to ultra-violetradiation (253.7 nm) with in-tervening outgrowth of survivors gave rise to clear bacteriophage plaques. Isolation, propagation and partial purification of the new Shd-4L10 phages showed that they are similar in morphology to the Myxobacteriaphage Mx-4described earlier. The new phages retained the general charac-teristics of S. dystenteriae phageShd-4L3,including serological properties and phage typing. It is suggested that ultra-violet irradiation may have played a role in the transformation and excision of the presumed lysogen of S. dysenteriaestrain A into a lytic phase. PhageShd-4L10was subse-quently partially characterized. It has a density of 1.61, a DNA: protein ratio 0f 0.42 and thus a cryptogram of D/2:54.3/32.5:X/X: B/O. The phage was further characterised by fractionation of its protein using SDS-polyacrilamide gel electrophoresis. DNA extracted from phages was hy-drolysed with restriction endonuclease R., EcoR1. The restriction fragments were catalogued and their apparent molecular weights calculated from electrophoresis gels calibrated with frag-ments from DNA of coliphage ë. From the total fragments obtained with nuclease R., EcoR1, the apparent minimum molecular weight of phage Shd-4L10DNA was found to be 54.3 x 106 Daltons. The molecular weight of the phage DNA was also calculated from measurements of contour length of purified DNA samples, using the formula MW = 1.97 x 1010 l/(magnification), where l is the measured length of DNA in centimetres). The very close relatedness with phage Shd-4L3 was confirmed by these techniques.

AJOL African Journals Online