Ancestry of the Brazilian TP53 c.1010G>A (p.Arg337His,R337H) Founder Mutation: Clues from Haplotyping of Short Tandem Repeats on Chromosome 17p

Rare germline mutations in TP53 (17p13.1) cause a highly penetrant predisposition to a specific spectrum of early cancers, defining the Li-Fraumeni Syndrome (LFS). A germline mutation at codon 337 (p.Arg337His, c1010G>A) is found in about 0.3% of the population of Southern Brazil. This mutation is associated with partially penetrant LFS traits and is found in the germline of patients with early cancers of the LFS spectrum unselected for familial history. To characterize the extended haplotypes carrying the mutation, we have genotyped 9 short tandem repeats on chromosome 17p in 12 trios of Brazilian p.Arg337His carriers. Results confirm that all share a common ancestor haplotype of Caucasian/Portuguese-Iberic origin, distant in about 72–84 generations (2000 years assuming a 25 years intergenerational distance) and thus pre-dating European migration to Brazil. So far, the founder p.Arg337His haplotype has not been detected outside Brazil, with the exception of two residents of Portugal, one of them of Brazilian origin. On the other hand, increased meiotic recombination in p.Arg337His carriers may account for higher than expected haplotype diversity. Further studies comparing haplotypes in populations of Brazil and of other areas of Portuguese migration are needed to understand the historical context of this mutation in Brazil.     

Skull osteology of Vipera walser (Squamata,Viperidae): Description,variability, ontogeny,and diagnostic characters in comparison to other Italian vipers

Vipera walser is the most recently recognized European viper. This rare species is endemic to a small area in the Piedmont Alps of Italy, but its closest relatives are found among the Caucasian viper species. In order to provide a starting point for a phylogenetic and biogeographic investigation based on osteology, and including fossils remains, we analyzed four specimens of V. walser and compared them with specimens of the four other Italian viper species. Based on these specimens, we improved the diagnosis of V. walser and provided a first evaluation of intraspecific variability and ontogenetic variation. The skull of V. walser is subject to significant variation, most likely related to ontogeny in some cases (i.e., development of the parietal crest, development of the basioccipital process, shape of the posterior margin of the parabasisphenoid, shape of the quadrate). Based on the studied material, it is possible to distinguish V. walser from the other Italian vipers by the shape of the occipital crest of the supraoccipital, which is posteriorly directed, whereas it is laterally directed in the other species. The osteological diagnosibility provides further support for the validity of V. walser as a distinct species from Vipera berus.     

The CXC Chemokine-degrading Protease SpyCep of Streptococcus pyogenes Promotes Its Uptake into Endothelial Cells

Streptococcus pyogenes expresses the LPXTG motif-containing cell envelope serine protease SpyCep (also called ScpC, PrtS) that degrades and inactivates the major chemoattractant interleukin 8 (IL-8), thereby impairing host neutrophil recruitment. In this study, we identified a novel function of SpyCep: the ability to mediate uptake into primary human endothelial cells. SpyCep triggered its uptake into endothelial cells but not into human epithelial cells originating from pharynx or lung, indicating an endothelial cell-specific uptake mechanism. SpyCep mediated cellular invasion by an endosomal/lysosomal pathway distinct from the caveolae-mediated invasion pathway of S. pyogenes. Recombinant expression and purification of proteolytically active SpyCep and a series of subfragments allowed functional dissection of the domains responsible for endothelial cell invasion and IL-8 degradation. The N-terminal PR domain was sufficient to mediate endothelial cell invasion, whereas for IL-8-degrading activity, the protease domain and the flanking A domain were required. A polyclonal rabbit serum raised against the recombinant protease efficiently blocked the invasion-mediating activity of SpyCep but not its proteolytic function, further indicating that SpyCep-mediated internalization is independent from its enzymatic activity. SpyCep may thus specifically mediate its own uptake as secreted protein into human endothelial cells.     

Differentiation of Purkinje fibres and ordinary ventricular and atrial myocytes in the bovine heart: an immuno-and enzyme histochemical study

Summary The differentiation of Purkinje fibres and ordinary ventricular and atrial myocytes in bovine hearts was studied with specific antibodies against M-line proteins (MM-creatine kinase and myomesin) and with enzyme histochemistry (succinate dehydrogenase and mitochondrial glycerol-3-phosphate dehydrogenase). MM-creatine kinase was detected at an earlier stage in Purkinje fibres and atrial myocytes than in ordinary ventricular myocytes. The findings are in agreement with previous ultrastructural observations that an earlier appearance of a dense M-band occurs in Purkinje fibres than in ordinary ventricular myocytes. Myomesin was detected in all three cell types even at early foetal stages, in accordance with suggestions that it is an integral component of the myofibrillar structure. The activity of succinate dehydrogenase gradually increased in both ordinary ventricular and atrial myocytes, while the activity of mitochondrial glycerol-3-phosphate dehydrogenase was high at different stages of early foetal development in the two tissues, finally becoming low in the adult stage. The activity of succinate dehydrogenase and mitochondrial glycerol-3-phosphate dehydrogenase seemed to remain unchanged in the Purkinje fibres from early to late foetal stages. The present study shows that the Purkinje fibres are already different from ordinary ventricular myocytes at early foetal stages and that the two cell types differentiate in different ways. It is concluded that there are also developmental differences between ordinary ventricular and atrial myocytes.