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In the present study, 10 short tandem repeats (STR) (HPRTB, DXS6789, DXS6799, DXS6804, DXS7130, DXS7132, DXS7133, DXS7423, DXS7424, and DXS8378) on X chromosome were investigated among four ethnic populations (431 individuals) in northwest of China, in order to learn about the genetic diversity, forensic suitability, and possible genetic affinities of the populations. The polymorphism information content (PIC) values for the ten loci range from 0.340 to 0.810, and the observed heterozygosity values for the ten loci range from 0.397 to 0.860, the results indicated that the ten loci have a moderate degree of variability in the four populations, and each population has its own characteristics of genetic structure. A Neighbor-joining (NJ) tree constructed on the basis of the generated data shows very low genetic distance between Han, Mongolian and Tibetan, Dongxiang and Tu as well as between Salar and Bonan populations. Our results based on genetic distance analysis are consistent with the results of earlier studies based on linguistics and the immigration history and origin of these populations. These STR loci on the X chromosome studied here are not only useful in showing significant genetic variation between the populations, but also are suitable for human identity testing among the four populations.

Klebsiella pneumoniae is a common human commensal and opportunistic pathogen. In recent years, the clinical isolation and resistance rates of K. pneumoniae have shown a yearly increase, leading to a special interest in mobile genetic elements. Prophages are a representative class of mobile genetic elements that can carry host-friendly genes, transfer horizontally between strains, and coevolve with the host’s genome. In this study, we identified 15,946 prophages from the genomes of 1437 fully assembled K. pneumoniae deposited in the NCBI database, with 9755 prophages on chromosomes and 6191 prophages on plasmids. We found prophages to be notably diverse and widely disseminated in the K. pneumoniae genomes. The K. pneumoniae prophages encoded multiple putative virulence factors and antibiotic resistance genes. The comparison of strain types with prophage types suggests that the two may be related. The differences in GC content between the same type of prophages and the genomic region in which they were located indicates the alien properties of the prophages. The overall distribution of GC content suggests that prophages integrated on chromosomes and plasmids may have different evolutionary characteristics. These results suggest a high prevalence of prophages in the K. pneumoniae genome and highlight the effect of prophages on strain characterization.