R. Majumder et al., PHYSICAL MAP OF THE GENOME OF VIBRIO-CHOLERAE 569B AND LOCALIZATION OF GENETIC-MARKERS, Journal of bacteriology, 178(4), 1996, pp. 1105-1112
A combined physical and genetic map of the genome of the classical O1
hypertoxinogenic strain 569B of Vibrio cholerae has been constructed,
The enzymes NotI, SfiI and CeuI generated DNA fragments of suitable si
ze distribution that could be resolved by pulsed-field gel electrophor
esis, The digests produced 37, 22, and 7 fragments, respectively, The
CeuI maps of the genomes of strains 569B and O395, constructed by part
ial restriction digestion, were identical, and the data are consistent
with the concept of circular chromosomes, The genome size of each of
the strains was estimated to be about 3.2 Mb, The NotI and SfiI digest
ion profiles of the genomic DNAs of strains 569B and O395 exhibited di
stinct restriction fragment length polymorphism. The linkages between
the 37 NotI fragments of the genome of strain 569B were determined by
combining three approaches: isolation of linking clones, analysis of p
artial digestion fragments, and identification of NotI fragments in is
olated CeuI and SfiI fragments. To align linked fragments precisely, N
otI-digested genomic DNA was end labeled and separated in the same gel
with the NotI-digested DNA to be probed with linking clones, This als
o allowed the identification of smaller restriction fragments that are
not visible in ethidium bromide-stained gels, The presence of repetit
ive DNA sequences in the V. cholerae 569B genome has been demonstrated
, Twenty cloned homologous and heterologous genes and seven rrn operon
s have been positioned on the physical map, The two copies of the Ctx
genetic element in the genome of strain 569B are located about 1,000 k
b apart.