A carbapenem-resistant Klebsiella pneumoniae isolate harboring KPC-1 from Italy

Carbapenem-resistant gram-negative pathogens represent an emerging threat to the management of hospital-acquired infections. Although the isolation of carbapenem-resistant enterobacteriaceae remains unusual, the frequency of carbapenemases producing Klebsiella pneumoniae is increasing in different geographic regions: the majority of isolates has been collected in the USA, but recently KPC-producing K. pneumoniae were reported from China, Israel, Greece, France, Norway and Sweden. We report a KPC 1-producing K. pneumoniae isolate from Italy. This datum enlarges the geographical area where the KPC-producing K. pneumoniae strains are diffuse.     

Staphylococcus aureus cell wall structure and dynamics during host-pathogen interaction

Peptidoglycan is the major structural component of the Staphylococcus aureus cell wall, in which it maintains cellular integrity, is the interface with the host, and its synthesis is targeted by some of the most crucial antibiotics developed. Despite this importance, and the wealth of data from in vitro studies, we do not understand the structure and dynamics of peptidoglycan during infection. In this study we have developed methods to harvest bacteria from an active infection in order to purify cell walls for biochemical analysis ex vivo. Isolated ex vivo bacterial cells are smaller than those actively growing in vitro, with thickened cell walls and reduced peptidoglycan crosslinking, similar to that of stationary phase cells. These features suggested a role for specific peptidoglycan homeostatic mechanisms in disease. As S. aureus missing penicillin binding protein 4 (PBP4) has reduced peptidoglycan crosslinking in vitro its role during infection was established. Loss of PBP4 resulted in an increased recovery of S. aureus from the livers of infected mice, which coincided with enhanced fitness within murine and human macrophages. Thicker cell walls correlate with reduced activity of peptidoglycan hydrolases. S. aureus has a family of 4 putative glucosaminidases, that are collectively crucial for growth. Loss of the major enzyme SagB, led to attenuation during murine infection and reduced survival in human macrophages. However, loss of the other three enzymes Atl, SagA and ScaH resulted in clustering dependent attenuation, in a zebrafish embryo, but not a murine, model of infection. A combination of pbp4 and sagB deficiencies resulted in a restoration of parental virulence. Our results, demonstrate the importance of appropriate cell wall structure and dynamics during pathogenesis, providing new insight to the mechanisms of disease.     

Dinosaur Tracks as Paleogeographic Constraints: New Scenarios for the Cretaceous Geography of the Periadriatic Region

A really unexpected finding of sauropod and theropod footprints in southern Latium raises to four the number of the trampled levels recognized in central and southern Italy. After the recent findings in Latest Jurassic and Early, mid and Late Cretaceous carbonate platform deposits of the Periadriatic region, dinosaur footprints seem to provide very important paleogeographic constraints for reconstructing the geodynamic history of the Mediterranean area. The presence of a varied ichnoassociation makes acceptance of the current paleogeographic models concerning the relative and absolute position of the Laziale-Abruzzese-Campano and of Apulian-Dinaric domains during the Late Cretaceous more and more problematic. Dinosaur footprints, combined with other paleontological data, demonstrate that these areas were never completely pulled apart by deep seaways, while frequent or continuous links between them, and to southern and northern mainlands, probably persisted. These data also allowed us to improve our understanding of the timing of the Mesozoic plate motion in this segment of the Western Tethys.     

Hypohidrotic ectodermal dysplasia

Summary A family carrying the X-linked gene for hypohidrotic ectodermal dysplasia (hereditary ectodermal polydysplasia or Christ-Siemens-Touraine syndrome) over three generations was monitored for more than 15 years. Two prenatal diagnoses were carried out by fetoscopy on skin biopsies. Polymorphic probes were used in the segregation analysis of the Xq11–21 region carried out on 30 members of the family. Current screening possiblitities for the carriers and prenatal diagnosis are discussed.     

Tandemly duplicated Arabidopsis genes that encode polygalacturonase-inhibiting proteins are regulated coordinately by different signal transduction pathways in response to fungal infection

Polygalacturonase-inhibiting proteins (PGIPs) are plant proteins that counteract fungal polygalacturonases, which are important virulence factors. Like many other plant defense proteins, PGIPs are encoded by gene families, but the roles of individual genes in these families are poorly understood. Here, we show that in Arabidopsis, two tandemly duplicated PGIP genes are upregulated coordinately in response to Botrytis cinerea infection, but through separate signal transduction pathways. AtPGIP2 expression is mediated by jasmonate and requires COI1 and JAR1, whereas AtPGIP1 expression is upregulated strongly by oligogalacturonides but is unaffected by salicylic acid, jasmonate, or ethylene. Both AtPGIP1 and AtPGIP2 encode functional inhibitors of polygalacturonase from Botrytis, and their overexpression in Arabidopsis significantly reduces Botrytis disease symptoms. Therefore, gene duplication followed by the divergence of promoter regions may result in different modes of regulation of similar defensive proteins, thereby enhancing the likelihood of defense gene activation during pathogen infection.     

Phylogenetic Properties of RNA Viruses

A new word, phylodynamics, was coined to emphasize the interconnection between phylogenetic properties, as observed for instance in a phylogenetic tree, and the epidemic dynamics of viruses, where selection, mediated by the host immune response, and transmission play a crucial role. The challenges faced when investigating the evolution of RNA viruses call for a virtuous loop of data collection, data analysis and modeling. This already resulted both in the collection of massive sequences databases and in the formulation of hypotheses on the main mechanisms driving qualitative differences observed in the (reconstructed) evolutionary patterns of different RNA viruses. Qualitatively, it has been observed that selection driven by the host immune response induces an uneven survival ability among co-existing strains. As a consequence, the imbalance level of the phylogenetic tree is manifestly more pronounced if compared to the case when the interaction with the host immune system does not play a central role in the evolutive dynamics. While many imbalance metrics have been introduced, reliable methods to discriminate in a quantitative way different level of imbalance are still lacking. In our work, we reconstruct and analyze the phylogenetic trees of six RNA viruses, with a special emphasis on the human Influenza A virus, due to its relevance for vaccine preparation as well as for the theoretical challenges it poses due to its peculiar evolutionary dynamics. We focus in particular on topological properties. We point out the limitation featured by standard imbalance metrics, and we introduce a new methodology with which we assign the correct imbalance level of the phylogenetic trees, in agreement with the phylodynamics of the viruses. Our thorough quantitative analysis allows for a deeper understanding of the evolutionary dynamics of the considered RNA viruses, which is crucial in order to provide a valuable framework for a quantitative assessment of theoretical predictions.     

Morphological changes induced in erythrocyte by amyloid beta peptide and glucose depletion: A combined atomic force microscopy and biochemical study

Circulating red blood cells (RBCs) undergo aging, a fundamental physiological phenomenon that regulates their turnover. We show that treatment with beta amyloid peptide 1–42 (Aβ) accelerates the occurrence of morphological and biochemical aging markers in human RBCs and influences the cell metabolism leading to intracellular ATP depletion. The morphological pattern has been monitored using Atomic Force Microscopy (AFM) imaging and measuring the RBCs' plasma membrane roughness employed as a morphological parameter capable to provide information on the structure and integrity of the membrane-skeleton. Results evidence that Aβ boosts the development of crenatures and proto-spicules simultaneously to acceleration in the weakening of the cell-cytoskeleton contacts and to the induction of peculiar nanoscale features on the cell membrane. Incubation in the presence of glucose can remove all but the latter Aβ-induced effects.Biochemical data demonstrate that contemporaneously to morphological and structural alterations, Aβ and glucose depletion trigger a complex signaling pathway involving caspase 3, protein kinase C (PKC) and nitric oxide derived metabolites.As a whole, the collected data revealed that, the damaging path induced by Aβ in RBC provide a sequence of morphological and functional intermediates following one another along RBC life span, including: (i) an acceleration in the development of shape alteration typically observed along the RBC's aging; (ii) the development of characteristic membrane features on the plasma membrane and (iii) triggering a complex signaling pathway involving caspase 3, PKC and nitric oxide derived metabolites.     

Mobile Communication in the Public Mind: Insights from Free Associations Related to Mobile Phone Base Stations

The number of people using mobile phones has dramatically increased. At the same time, many people are unsettled about the potential health effects from the electromagnetic fields generated by mobile phone base stations. Research indicates that the risks associated with base stations are perceived differently by experts, laypeople, and base station opponents. Using a free association method, we analyzed these differences in more detail. In our first study, we found no difference between experts and laypeople but a marked distinction in the associations of opponents as opposed to the first two groups. The prevalence of free associations in a large random sample from the general population was explored via correspondence analysis in the second study. People who assign high risks to mobile communication had different, more negative associations in mind (e.g., “senselessness,” “hazard”) compared to people with low risk-perception (e.g., “mast,” “acceptance”). Our research is in line with the assumption that the affect heuristic guides risk and benefit assessments, and highlights the role of affect in risk perception and communication.     

Exome Sequencing Identifies Rare Deleterious Mutations in DNA Repair Genes FANCC and BLM as Potential Breast Cancer Susceptibility Alleles

Despite intensive efforts using linkage and candidate gene approaches, the genetic etiology for the majority of families with a multi-generational breast cancer predisposition is unknown. In this study, we used whole-exome sequencing of thirty-three individuals from 15 breast cancer families to identify potential predisposing genes. Our analysis identified families with heterozygous, deleterious mutations in the DNA repair genes FANCC and BLM, which are responsible for the autosomal recessive disorders Fanconi Anemia and Bloom syndrome. In total, screening of all exons in these genes in 438 breast cancer families identified three with truncating mutations in FANCC and two with truncating mutations in BLM. Additional screening of FANCC mutation hotspot exons identified one pathogenic mutation among an additional 957 breast cancer families. Importantly, none of the deleterious mutations were identified among 464 healthy controls and are not reported in the 1,000 Genomes data. Given the rarity of Fanconi Anemia and Bloom syndrome disorders among Caucasian populations, the finding of multiple deleterious mutations in these critical DNA repair genes among high-risk breast cancer families is intriguing and suggestive of a predisposing role. Our data demonstrate the utility of intra-family exome-sequencing approaches to uncover cancer predisposition genes, but highlight the major challenge of definitively validating candidates where the incidence of sporadic disease is high, germline mutations are not fully penetrant, and individual predisposition genes may only account for a tiny proportion of breast cancer families.