Genetic analysis of type 2 tri-allelic pattern at TPOX locus in the Chinese Han population.

Tri-allelic patterns can occasionally be observed during the profiling of short tandem repeats (STRs) in routine forensic practice. In previous studies, the Type 2 tri-allelic pattern at TPOX has been widely studied in African and Brazilian populations. In this study, we investigated the incidence, rearrangement, and inheritance of the Type 2 tri-allelic pattern at the TPOX locus in a Chinese Han population. The frequency of the Type 2 pattern at TPOX was approximately 0.0189%, and the major extra allele was allele 11 in the Chinese Han population. Two major allelic combinations, 8/11 and 11/12, were observed, which are different from the configuration of that in both African and Brazilian populations. Tight linkage between alleles 11 and 12 was observed in the majority of the Type 2 pattern at TPOX in the Chinese Han population, while the location of the extra copy on chromosome 2 was validated, which shows an identical ancestral origin. The excess allelic combination 8/11 implies a homogeneous origin and tight linkage relationship. However, the rearrangement in the Type 2 pattern with the 8/11 allelic combination remained unknown. Altogether, these results show the configuration of the Type 2 tri-allelic pattern at the TPOX locus in the Chinese Han population, which will assist in the understanding of the Type 2 tri-allelic pattern at the TPOX locus in the global population.

A Genome-Wide Screen Reveals that the Vibrio cholerae Phosphoenolpyruvate Phosphotransferase System Modulates Virulence Gene Expression.

Diverse environmental stimuli and a complex network of regulatory factors are known to modulate expression of Vibrio cholerae's principal virulence factors. However, there is relatively little known about how metabolic factors impinge upon the pathogen's well-characterized cascade of transcription factors that induce expression of cholera toxin and the toxin-coregulated pilus (TCP). Here, we used a transposon insertion site (TIS) sequencing-based strategy to identify new factors required for expression of tcpA, which encodes the major subunit of TCP, the organism's chief intestinal colonization factor. Besides identifying most of the genes known to modulate tcpA expression, the screen yielded ptsI and ptsH, which encode the enzyme I (EI) and Hpr components of the V. cholerae phosphoenolpyruvate phosphotransferase system (PTS). In addition to reduced expression of TcpA, strains lacking EI, Hpr, or the associated EIIA(Glc) protein produced less cholera toxin (CT) and had a diminished capacity to colonize the infant mouse intestine. The PTS modulates virulence gene expression by regulating expression of tcpPH and aphAB, which themselves control expression of toxT, the central activator of virulence gene expression. One mechanism by which PTS promotes virulence gene expression appears to be by modulating the amounts of intracellular cyclic AMP (cAMP). Our findings reveal that the V. cholerae PTS is an additional modulator of the ToxT regulon and demonstrate the potency of loss-of-function TIS sequencing screens for defining regulatory networks.