In a search for the genetic basis for the structural difference between the related Streptococcus pneumoniae capsular serotypes 15B and 15C and for the reported reversible switching between these serotypes, the corresponding capsular polysaccharide synthesis (cps) loci were investigated by keeping in mind that at the structural level, the capsules differ only in O acetylation. The cps locus of a serotype 15B strain was identified, partially PCR amplified with primers based on the related serotype 14 sequence, and sequenced. Sequence analysis revealed, among other open reading frames, an intact open reading frame (designated cps15bM) whose product, at the protein level, exhibited characteristics of previously identified acetyltransferases. Genetic analysis of the corresponding region in a serotype15C strain indicated that the same gene was present but had a premature stop in translation. Closer analysis indicated that the serotype 15B gene contained a short tandem TA repeat consisting of eight TA units. In serotype 15C, this gene contained nine TA units that resulted in a frameshift and a truncated product. Genetic analysis of 17 serotype 15B and 15C clinical isolates revealed a perfect correlation between the serotype and the length of the short tandem repeat in the putative O-acetyltransferase gene. The number of TA repeating units varied between seven and nine in the various isolates. Together, the data strongly suggest that the structural difference between serotypes 15B and 15C is based on variation in the short tandem TA repeat in the O-acetyltransferase gene and that the transition between serotypes is due to slipped-strand mispairing with deletion or insertion of TA units in the cps15bM gene.The human pathogen Streptococcus pneumoniae (pneumococcus) is a major cause of respiratory tract infections, bacteremia, and meningitis, particularly in young children and the elderly (32, 35). One of the prime virulence determinants of this bacterium is the polysaccharide capsule (CPS). This structure is thought to protect the bacterium against harmful environmental conditions and exhibits antiphagocytic properties (8). The CPS is composed of saccharide repeating units that are polymerized into a polysaccharide chain. Thus far, 90 different capsule serotypes have been identified. The diversity is based on variation in the carbohydrate structure of the oligosaccharide units or the attached side groups (18).The genes encoding the enzymes involved in CPS biosynthesis are clustered on the bacterial genome in the capsular polysaccharide synthesis (cps) locus. The cps locus is typically flanked by the genes dexB and aliA. At this time, the cps loci of 16 different serotypes have been sequenced (3, 12, 13, 16, 20, 23, 24, 26-29, 33, 34, 42, 50). Nearly all loci have the same genetic organization (38). The first four genes of the loci are conserved in almost all serotypes, and it has been demonstrated that three of these genes encode enzymes involved in the regulation of capsule production (5,7,30,54). The central parts of ...

The Bovini tribe contains domestic and wild cattle-like species, several of which are cross-fertile. We present a completely resolved Y-chromosomal phylogeny, which is better in agreement with autosomal phylogeny, morphological data, cross-fertility and estimates of divergence times than mitochondrial data. The tree links Bos grunniens (yak) to Bison, so the commonly accepted Bos genus is not monophyletic. Therefore, we advocate the term Poephagus as designation of yak. This work illustrates the resolving power of Y-chromosomal variation for cladistic studies of closely related species.

By their paternal transmission, Y-chromosomal haplotypes are sensitive markers of population history and male-mediated introgression. Previous studies identified biallelic single-nucleotide variants in the SRY, ZFY and DDX3Y genes, which in domestic goats identified four major Y-chromosomal haplotypes, Y1A, Y1B, Y2A and Y2B, with a marked geographical partitioning. Here, we extracted goat Y-chromosomal variants from whole-genome sequences of 386 domestic goats (75 breeds) and seven wild goat species, which were generated by the VarGoats goat genome project. Phylogenetic analyses indicated domestic haplogroups corresponding to Y1B, Y2A and Y2B, respectively, whereas Y1A is split into Y1AA and Y1AB. All five haplogroups were detected in 26 ancient DNA samples from southeast Europe or Asia. Haplotypes from presentday bezoars are not shared with domestic goats and are attached to deep nodes of the trees and networks. Haplogroup distributions for 186 domestic breeds indicate ancient paternal population bottlenecks and expansions during migrations into northern Europe, eastern and southern Asia, and Africa south of the Sahara. In addition, sharing of haplogroups indicates male-mediated introgressions, most notably an early gene