Investigating Potential Chromosomal Rearrangements during Laboratory Culture of Neisseria gonorrhoeae

Genomic Diversity and Chromosomal Rearrangements in Neisseria gonorrhoeae and Neisseria meningitidis

Chromosomal rearrangements in N. gonorrhoeae and N. meningitidis were studied with the determination of mobile elements and their role in rearrangements. The results of whole-genome sequencing and de novo genome assembly for 50 N. gonorrhoeae isolates collected in Russia were compared with 96 genomes of N. gonorrhoeae and 138 genomes of N. meningitidis from the databases. Rearrangement events with the determination of the coordinates of syntenic blocks were analyzed using the SibeliaZ software v.1.2.5, the minimum number of events that allow one genome to pass into another was calculated using the DCJ-indel model using the UniMoG program v.1.0. Population-level analysis revealed a stronger correlation between changes in the gene order and phylogenetic proximity for N. meningitidis in contrast to N. gonorrhoeae. Mobile elements were identified, including Correa elements; Spencer-Smith elements (in N. gonorrhoeae); Neisserial intergenic mosaic elements; IS elements of IS5, IS30, IS110, IS1595 groups; Nf1-Nf3 prophages; NgoФ1-NgoФ9 prophages; and Mu-like prophages Pnm1, Pnm2, MuMenB (in N. meningitidis). More than 44% of the observed rearrangements most likely occurred with the participation of mobile elements, including prophages. No differences were found between the Russian and global N. gonorrhoeae population both in terms of rearrangement events and in the number of transposable elements in genomes.

Pulsed Field Gel Electrophoresis: Past, present, and future

Pulsed Field Gel Electrophoresis (PFGE) has been considered for many years the 'gold-standard' for characterizing many pathogenic organisms as well as for subtyping bacterial species causing infection outbreaks. This article reviews the basic principles of PFGE and it includes the main advantages and limitations of the different electrode configurations that have been used in PFGE equipment and their influence on the DNA electrophoretic separation. Remarkably, we summarize here the most relevant theoretical and practical aspects that we have learned for more than 20 years developing and using the miniaturized PFGE systems. We also discussed the theoretical aspects related to DNA migration in PFGE agarose gels. It served as the basis for simulating the DNA electrophoretic patterns in CHEF mini gels and mini-chambers during experimental design and optimization. A critical comparison between standard and miniaturized PFGE systems, as well as the enzymatic and non-enzymatic methods for intact immobilized DNA preparation, is provided throughout the review. The PFGE current applications, advantages, limitations and future challenges of the methodology are also discussed.