Biology subjects

Venditti, C.

Publications and source records attributed to Venditti, C..

3 recordsLinked to original sources

bioRxiv2018

Epidemiologal investigation of an Acinetobacter baumannii outbreak using Core Genome Multilocus Sequence Typing

Carbapenem-resistant (CR) Acinetobacter baumannii is a serious nosocomial pathogen able to cause a variety of serious, often life-threatening infections and outbreaks. We aimed to investigate the molecular epidemiology of clinical isolates of CR-A. baumannii from an outbreak occurred in the intensive care unit (ICU) of our hospital.\n\nFrom January to April 2017, 13 CR-A. baumannii isolates were collected at the \"L. Spallanzani\" hospital, Rome, Italy; typing was performed by repetitive extragenetic palindromic-based (rep)- PCR-based DiversiLab system and WGS data were used for in silico analysis of traditional MLST types, for identifying resistance genes and for core genome multi locus sequence typing (cgMLST) analysis. Epidemiological data were obtained from hospital records.\n\nStrains were cultured from 7 patients treated in the ICU of our hospital; all isolates showed a multi-drug resistant (MDR) profile, carrying the blaOXA-23 carbapenemase. Typing performed by rep-PCR and MLST showed that the isolates clustered into one group while the cgMLST approach, which uses 2690 gene targets to characterize the gene-by-gene allelic profile of A. baumannii, highlighted the presence of two cluster types. These results allowed us to identify two patients who entered the ICU already colonized by two different strains of CR-A. baumannii; we hypothesize that these two patients could be the source of two separate transmission chains.\n\nOur results show that whole-genome-DNA sequencing by cgMLST is a valuable tool, better suited for prompt epidemiological investigations than traditional typing methods because of its higher discriminatory ability in determining clonal relatedness.

molecular biology↗

bioRxiv2018

Extreme and rapid bursts of functional adaptations shape bite force in amniotes

Adaptation is the fundamental driver of functional and biomechanical evolution and can be linked to rates of phenotypic trait evolution. Significant shifts in evolutionary rates are seen as instances of exceptional adaptation. However, whether or not signatures of exceptional adaptations (elevated rates) can be distinguished from general adaptations (background rate) in biomechanical traits remains to be tested in a robust statistical framework. Here, we apply a recently developed phylogenetic statistical approach for detecting exceptional adaptations in bite force, in a large group of terrestrial vertebrates, the amniotes. Our results show that bite force in amniotes evolved through multiple bursts of exceptional changes, whereby whole groups - including Darwin';s finches, maniraptoran dinosaurs (group of non-avian dinosaurs including birds), anthropoids and hominins (the group of species including modern humans) - experienced significant rate increases compared to the background rate. However, in most parts of the amniote tree of life we find no exceptional rate increases, indicating that coevolution with body size was primarily responsible for the patterns observed in bite force. Our approach represents a template for future studies in functional morphology and biomechanics, where exceptional functional adaptations can be quantified and potentially linked to specific ecological factors underpinning major evolutionary radiations.

evolutionary biology↗

bioRxiv2017

150 million years of sustained increase in pterosaur flight efficiency

The long-term accumulation of biodiversity has been punctuated by remarkable evolutionary transitions that allowed organisms to exploit new ecological opportunities, and often resulted in large radiations of species. The Mesozoic flying reptiles - pterosaurs - which dominated the skies for over 150 million years (Myr), were the product of such a transition. The ancestors of pterosaurs were small and likely bipedal early archosaurs, which were certainly well adapted to terrestrial locomotion. More than 220 Myr ago, at some point in the Triassic, pterosaurs took flight and subsequently appear to have become capable and efficient flyers. However, the evolutionary processes that led to this efficiency remain enigmatic. Given the lack of proto-pterosaurs it is difficult to study how flight first evolved in this group, but we can test hypotheses about evolutionary changes to the energetics of locomotion following the transition to flight. Early pterosaurs were challenged by the c ...

evolutionary biology↗