Molecular diversity of Primula apennina and phylogeny of Primula Subsection Euauricula

Primula apennina Widmer is endemic to the North Apennines (Italy). ISSR were used to detect the genetic diversity within and among six populations representative of the species distribution range. High levels of genetic diversity were revealed both at population (PPB = 75.92%, HS = 0.204, Hpop = 0.319) and at species level (PPB = 96.95%, HT = 0.242, Hsp = 0.381). Nei gene diversity statistics (15.7%), Shannon diversity index (16.3%) and AMOVA (14%) detected a moderate level of interpopulation diversity. Principal coordinate and bayesian analyses clustered the populations in three major groups along a geographic gradient. The correlation between genetic and geographic distances was positive (Mantel test, r = 0.232). All together, these analyses revealed a weak but significant spatial genetic structure in P. apennina, with gene flow acting as a homogenizing force that prevents a stronger differentiation of populations. Conservation measures are suggested based on the observed pattern of genetic variability. P. apennina belongs to Primula subsect. Euauricula which includes 15 species distributed on the whole Alps and Apennines. A phylogenetic analysis was carried out using AFLP markers in order both to clarify the relationships among the species of subsection Euauricula that remained unresolved in previous works and to make some hypoteses on their evolutive dynamics. NJ, PCO and BAPS analyses strongly confirmed the monophyly of P. subsect. Euauricula and all the species form strongly supported clades. NJ tree topology suggested a simultaneous fragmentations of ancestral species in a large number of isolated populations that survived in refugia along the unglaciated margins of the Alps in response to the Pleistocene climatic oscillations.

Diversity of cwp loci in clinical isolates of Clostridium difficile

An increased incidence of Clostridium difficile infection (CDI) is associated with the emergence of epidemic strains characterised by high genetic diversity. Among the factors that may have a role in CDI there is a family of 29 paralogs, the cell wall proteins (CWPs), which compose the outer layer of the bacterial cell and are likely to be involved in colonisation. Previous studies have shown that 12 of the29 cwp genes are clustered in the same region, named after slpA (cwp1) the slpA locus, whereas the remaining 17 paralogs are distributed throughout the genome. The variability of 14 of these 17 cwp paralogs was determined in 40 C. difficile clinical isolates belonging to six of the currently prevailing PCR ribotypes. Based on sequence conservation, these cwp genes were divided into two groups, one comprising cwp loci having highly conserved sequences in all isolates, and the other 5 loci showing low genetic conservation between isolates of the same PCR ribotype as well as between different PCR ribotypes. Three conserved CWPs, Cwp16, Cwp18 and Cwp25, and two variable ones, Cwp26 and Cwp27, were characterised further by Western blot analysis of total cell extracts or S-layer preparations of the C. difficile clinical isolates. Expression of genetically invariable CWPs is well conserved in all isolates, while genetically variable CWPs are not always expressed at comparable levels even in strains containing identical sequences but belonging to different PCR ribotypes. In addition, we chose to analyse the immune response obtained in a protection experiment, carried out in hamsters, using a protein microarray approach to study the in vivo expression and the immunoreactivity of several surface proteins, including 18 Cwps.