Emerging neurotrophic role of GABAB receptors in neuronal circuit development

The proper development of highly organized structures in the central nervous system is a complex process during which key events – neurogenesis, migration, growth, differentiation, and synaptogenesis – have to take place in an appropriate manner to create functional neuronal networks. It is now well established that GABA, the main inhibitory neurotransmitter in the adult mammalian brain, plays more than a classical inhibitory role and can function as an important developmental signal early in life. GABA binds to chloride-permeable ionotropic GABA(A) receptors and to G-protein-coupled GABA(B) receptors (GABA(B)-Rs). Although most of the trophic actions of GABA have been attributed to the activation of GABA(A) receptors, recent advances show that GABA(B)-Rs also regulate fundamental steps of network development. This review summarizes some of the recent progress about the neurotrophic role of GABA(B)-Rs to neuronal development

Hidden effects of habitat restoration on the persistence of pollination networks

Past and recent studies have focused on the effects of global change drivers such as species invasions on species extinction. However, as we enter the United Nations Decade of Ecosystem Restoration the aim must switch to understanding how invasive-species management affects the persistence of the remaining species in a community. Focusing on plant-pollinator interactions, we test how species persistence is affected by restoration via the removal of invasive plant species. Restoration had a clear positive effect on plant persistence, whereas there was no difference between across treatments for pollinator persistence in the early season, but a clear effect in late season, with higher persistence in unrestored sites. Network structure affected only pollinator persistence, while centrality had a strong positive effect on both plants and pollinators. Our results suggest a hidden effect of invasive plants—although they may compete with native plant species, invasive plants may provide important resources for pollinators, at least in the short term

EVOLUTION, COMPARATIVE GENOMICS AND GENOMIC EPIDEMIOLOGY OF BACTERIA OF PUBLIC HEALTH IMPORTANCE

La presente tesi \ue8 incentrata sull'epidemiologia genomica delle infezioni batteriche ospedaliere. L'ambiente ospedaliero \ue8 peculiare, in quanto al suo interno si concentrano un elevato numero di agenti batterici, pazienti con un sistema immunitario debole e un uso massiccio di sostanze antimicrobiche. Questa combinazione favorisce lo sviluppo e la selezione di ceppi resistenti agli antibiotici e la diffusione di infezioni opportunistiche: in generale il prosperare dei patogeni nosocomiali. Alcune tecniche all'avanguardia per lo studio di questo tipo di infezioni sono basate sull\u2019uso della genomica e di approcci evoluzionistici: esse permettono di conoscere le caratteristiche genomiche dei ceppi batterici e di ricostruire la loro storia evolutiva. Grazie alla possibilit\ue0 di sequenziare il DNA ad un prezzo sempre pi\uf9 economico, i progetti di ricerca sono supportati da un numero sempre crescente di genomi e i dati genomici depositati nelle banche dati sono in crescita esponenziale: questo rende possibile eseguire una variet\ue0 sempre maggiore di analisi. Il primo lavoro qui riportato descrive l'evoluzione del Clonal Complex 258 (CC258) di Klebsiella pneumoniae. Le mutazioni puntiformi (single nucleotide polymorphism, SNP) hanno permesso di ricostruire la filogenesi globale di tutta la specie e di collocare il CC258 nel suo contesto evolutivo. Successivamente, \ue8 stato possibile rilevare la presenza di una ricombinazione di 1,3 Mb nei genomi del clade in analisi. Un\u2019analisi del molecular clock ha poi consentito di datare sia questo che gli altri eventi di ricombinazione scoperti in lavori precedenti. Questi risultati sono stati usati per completare il quadro della storia evolutiva del CC258, caratterizzata da frequenti eventi di macro-ricombinazione. Un\u2019evoluzione rapida e caratterizzata da scambi di elevate quantit\ue0 di informazioni genomiche \ue8 una caratteristica comune ad altri patogeni nosocomiali che sviluppano fenotipi da "superbatteri". Sebbene frequente, il modello di evoluzione per macro-ricombinazioni non \ue8 comune a tutti i batteri responsabili di infezioni nosocomiali. Un\u2019eccezione \ue8 il ceppo SMAL di Acinetobacter baumannii, presentato in un altro sottoprogetto di questa tesi. In questo lavoro sono stati analizzati i genomi del sequence type (ST) 78 di A. baumannii. La filogenesi e la genomica comparativa hanno rivelato la presenza di due differenti cladi all'interno del ST che presentano differenti "stili" evolutivi. Un gruppo (contenente i genomi SMAL) \ue8 caratterizzato da una minore variabilit\ue0 del contenuto genico e dalla presenza di un numero pi\uf9 elevato di copie di insertion sequence (IS). Una IS interrompe il gene comEC/rec2 in tutti i genomi SMAL. Questo gene codifica per una proteina coinvolta nell\u2019acquisizione del DNA esogeno, quindi la sua inattivazione limita lo scambio di geni. Questo suggerisce una spiegazione per la bassa plasticit\ue0 genomica. In un altro lavoro presentato in questa tesi, l'epidemiologia genomica \ue8 stata applicata per ricostruire la diffusione di un focolaio epidemico di K. pneumoniae in un\u2019unit\ue0 di terapia intensiva ospedaliera. In un primo momento, \ue8 stato utilizzato un approccio filogenetico per separare gli isolati appartenenti all'epidemia da quelli sporadici. Poi le date di isolamento e gli SNP genomici hanno permesso di costruire una rete genomica che modellasse la propagazione delle infezioni nel reparto. La ricostruzione ha indicato una diffusione radiale del patogeno dal paziente zero a tutti gli altri infetti, rivelando cos\uec un errore sistematico nelle procedure di biosicurezza dell'ospedale. Questa applicazione quasi forense dell'epidemiologia genomica \ue8 stata utilizzata anche in altri due lavori qui presentati, entrambi riguardanti la ricostruzione di infezioni alimentari. In uno degli articoli, incentrato su Salmonella enterica, l\u2019analisi filogenetica \ue8 stata eseguita solamente con gli SNP sinonimi al fine di filtrare le mutazioni patoadattative. Nell'altro lavoro sono stati utilizzati dati epidemiologici, tipizzazione molecolare e filogenesi basata sugli SNP per studiare l'infezione di nove isolati di Listeria monocytogenes, che si ritenevano essere parte dello stesso focolaio e alla fine sono risultati genomicamente non correlati. Infine, viene qui presentato anche un articolo di review riguardante l'epidemiologia genomica. L'articolo \ue8 focalizzato sulle ultime pubblicazioni ad alto impatto che analizzano l'evoluzione genomica degli agenti patogeni batterici e le dinamiche di propagazione delle epidemie in brevi periodi di tempo. L'articolo descrive, infine, le ultime ricostruzioni epidemiologiche a livello storico, che sono possibili grazie alle moderne tecnologie di isolamento e sequenza del DNA.The present thesis is focused on genomic epidemiology of bacterial hospital infections. The hospital environment is unique, as it concentrates a high number of bacterial agents, frequent antibiotic use, and patients with weak immune systems. This combination favours the development and selection of antibiotic resistant strains and the spread of opportunistic infections: in general the thriving of nosocomial pathogens. Genomics and evolutionary approaches have emerged as the cutting edge tools for studying this kind of infections, allowing to study the genomic features of bacterial strains and their evolution. Thanks to the possibility to sequence DNA at a constantly cheaper price, research projects are supported by a growing number of genomes and a considerable amount of genomic data is available in the databases, expanding the amount of possible investigations that can be performed. The first work presented here describes the evolution of the Clonal Complex 258 (CC258) of Klebsiella pneumoniae. Single nucleotide polymorphisms (SNPs) allowed to reconstruct the global phylogeny of the entire species and to collocate the CC258 in its evolutionary context. Furthermore, it was possible to detect the presence of a 1.3 Mb recombination in the genomes of the clade in analysis. A molecular clock approach allowed to date this and other previously discovered recombination events. These findings were used to complete the picture of the evolutionary history of CC258, which is characterized by frequent macro-recombination events. A quick evolutive strategy characterized by exchange of high amount of information is a common feature to other nosocomial pathogens, which develop \u201csuperbug\u201d phenotypes. Although common, the macro-recombination evolution model is not shared by all nosocomial infection bacteria. One exception is the SMAL strain of Acinetobacter baumannii, presented in another subproject of this thesis. In this work, the genomes of Sequence Type (ST) 78 of A. baumannii were analyzed. Phylogeny and comparative genomics revealed the presence of two different clades within the ST, presenting different evolutive \u201clifestyles\u201d. One group (containing the SMAL genomes) was characterized by a lower gene content variability and by the presence of a higher copy number of insertion sequences (ISs). One IS interrupts the comEC/rec2 gene in all the SMAL genomes. This gene codes for a protein involved in the exogenous DNA importation, thus its inactivation limits the gene exchange, suggesting an explanation for the low genomic plasticity. In another work presented in this document, genomic epidemiology was applied to reconstruct the spreading routes of a K. pneumoniae epidemic event in an hospital intensive care unit. At first, a phylogenetic approach was used to separate the isolates that belonged to the outbreak from the sporadic ones. Then the isolation dates and genomic SNPs allowed to build a genomic network, which modelled the chain of infection events in the ward. The reconstruction suggested a star-like diffusion of the pathogen from patient zero to the other infected ones, thus revealing a systematic error in the biosafety procedures of the hospital. This almost-forensic application of genomic epidemiology was also used in two other works presented, both of them concerning the reconstruction of food-borne infections. In one of the works, focused on Salmonella enterica, only synonymous SNPs were used as input to a phylogenetic based investigation, in order to filter out pathoadaptative mutations. In the other article, epidemiological data, molecular typing and SNP-based phylogeny were used to investigate the infection of nine Listeria monocytogenes isolates, which were believed to be part of the same outbreak and in the end proved to be genomically unrelated. Lastly, a review paper on genomic epidemiology is also presented. The article is focused on the latest high impact publications analyzing the genome evolution of bacterial pathogens as well as the propagation dynamics of epidemic outbreaks in very short periods of time. The article also describes the latest historical epidemiological studies, which are possible thanks to modern DNA isolation and sequencing technologies

China e Estados Unidos: aumento e estreitamento das relações comerciais e a possibilidade de competição hegemônica

TCC (graduação) - Universidade Federal de Santa Catarina. Centro Sócio-Econômico. Economia.O objetivo desse trabalho é traçar o crescimento e declínio da hegemonia estadunidense no mundo a partir da 2ª Guerra Mundial. Paralelamente a isso, utilizando praticamente o mesmo recorte temporal, é traçado um panorama rápido sobre a economia chinesa de Mao-Tsé Tung com ênfase nas reformas de Deng-Xiao Ping. Após essas revisões históricas é feita uma análise estatística sobre o comércio exterior sinoamericano visando embasar a discussão final sobre a China sendo uma concorrente a hegemonia norte americana na atualidad

Multiple Klebsiella pneumoniae KPC Clones Contribute to an Extended Hospital Outbreak

The circulation of carbapenem-resistant Klebsiella pneumoniae (CRKP) is a significant problem worldwide. In this work we characterize the isolates and reconstruct the spread of a multi-clone epidemic event that occurred in an Intensive Care Unit in a hospital in Northern Italy. The event took place from August 2015 to May 2016 and involved 23 patients. Twelve of these patients were colonized by CRKP at the gastrointestinal level, while the other 11 were infected in various body districts. We retrospectively collected data on the inpatients and characterized a subset of the CRKP isolates using antibiotic resistance profiling and whole genome sequencing. A SNP-based phylogenetic approach was used to depict the evolutionary context of the obtained genomes, showing that 26 of the 32 isolates belong to three genome clusters, while the remaining six were classified as sporadic. The first genome cluster was composed of multi-resistant isolates of sequence type (ST) 512. Among those, two were resistant to colistin, one of which indicating the insurgence of resistance during an infection. One patient hospitalized in this period was colonized by two strains of CRKP, both carrying the blaKPC gene (variant KPC-3). The analysis of the genome contig containing the blaKPC locus indicates that the gene was not transmitted between the two isolates. The second infection cluster comprised four other genomes of ST512, while the third one (ST258) colonized 12 patients, causing five clinical infections and resulting in seven deaths. This cluster presented the highest level of antibiotic resistance, including colistin resistance in all 17 analyzed isolates. The three outbreaking clones did not present more virulence genes than the sporadic isolates and had different patterns of antibiotic resistance, however, were clearly distinct from the sporadic ones in terms of infection status, being the only ones causing overt infections

The COVID-19 Pandemic Sparked off a Large-Scale Outbreak of Carbapenem-Resistant Acinetobacter baumannii from the Endemic Strains at an Italian Hospital

Acinetobacter baumannii is a nosocomial pathogen that poses a serious threat due to the rise of incidence of multidrug-resistant (MDR) strains. During the COVID-19 pandemic, MDR A. baumannii clones have caused several outbreaks worldwide. Here, we describe a detailed investigation of an MDR A. baumannii outbreak that occurred at Policlinico San Matteo (Pavia, Italy). A total of 96 A. baumannii strains, isolated between January and July 2020 from 41 inpatients (both SARS-CoV-2 positive and negative) in different wards, were characterized by phenotypic and genomic analyses combining Illumina and Nanopore sequencing. Antibiotic susceptibility testing revealed that all isolates were resistant to carbapenems, and the sequence analysis attributed this to the carbapenemase gene blaOXA-23. Virulence factor screening unveiled that all strains carried determinants for biofilm formation, while plasmid analysis revealed the presence of two plasmids, one of which was ~100 kbp long and encoded a phage sequence. A core genome-based phylogeny was inferred to integrate outbreak strain genomes with background genomes from public databases and the local surveillance program. All strains belonged to the globally disseminated sequence type 2 (ST2) clone and were mainly divided into two clades. Isolates from the outbreak clustered with surveillance isolates from 2019, suggesting that the outbreak was caused by two strains that were already circulating in the hospital before the start of the pandemic. The intensive spread of A. baumannii in the hospital was enhanced by the extreme emergency situation of the first COVID-19 pandemic wave that resulted in reduced attention to infection prevention and control practices. IMPORTANCE: The COVID-19 pandemic, especially during the first wave, posed a great challenge to the hospital management and generally promoted nosocomial pathogen dissemination. MDR A. baumannii can easily spread and persist for a long time on surfaces, causing outbreaks in health care settings. Infection prevention and control practices, epidemiological surveillance, and microbiological screening are fundamental in order to control such outbreaks. Here, we sequenced the genomes of 96 isolates from an outbreak of MDR A. baumannii strains using both short- and long-read technology in order to reconstruct the outbreak events in fine detail. The sequence data demonstrated that two endemic clones of MDR A. baumannii were the source of this large hospital outbreak during the first COVID-19 pandemic wave, confirming the effect of COVID-19 emergency disrupting the protection provided by the use of the standard prevention procedures

Natural History of Pseudoboine Snakes

Even though natural history information is crucial for answering key ecological, evolutionary, and conservation questions, basic studies are still lacking for Neotropical snakes. This study aims at contributing to the knowledge of the Neotropical tribe Pseudoboini, based on literature data, analysis of museum specimens and unpublished data. The tribe is mainly composed of moderate-sized snakes, although small and large-sized snakes also occur in the clade. Mean fecundity ranged from two (Rodriguesophis iglesiasi) to 29 eggs (Clelia plumbea) and the species are predominantly terrestrial and nocturnal. Most species are diet specialists and lizards are the most commonly consumed prey (found in the diet of 29 species), followed by small mammals (consumed by 20 species) and snakes (consumed by 18 species). Although the tribe Pseudoboini appears to be well studied, for 15 species (32%) only a small amount of information or none was available. We hope that our study can motivate research on the least known species.Apesar de estudos de história natural serem cruciais para responder perguntas de ecologia, evolução e para estudos de conservação, ainda faltam informações básicas para diversas espécies neotropicais. O objetivo deste estudo é contribuir para o conhecimento de uma tribo de serpentes neotropicais, a tribo Pseudoboini, por meio de revisão bibliográfica, analises de espécimens depositados em coleções herpetológicas e dados não publicados. A tribo é composta predominantemente por serpents de tamanho médio, mas espécies de pequeno e grande tamanho também podem ser encontradas. A fecundidade média various de dois (Rodriguesophis iglesiasi) a 29 ovos (Clelia plumbea) e a maior parte das espécies parece ser terrestre e exibir hábitos noturnos. Além disso, grande parte das espécies é especialista em algum tipo de presa, sendo que lagarto é o tipo de presa mais consumida, encontrado na dieta de 29 espécies, seguido por pequenos mamiíferos (consumidos por 20 espécies) e serpentes (consumidas por 18 espécies). Apesar de ser aparentemente uma tribo bem estudada, para 15 espécies (32%) pouca ou nenhuma informação foi encontrada. Esperamos que este trabalho motive estudos semelhantes com as espécies menos conhecidas.This study was funded by FAPESP. MM thanks CNPq for a research fellowshi

A novel IncA/C1 group conjugative plasmid, encoding VIM-1 metallo-beta-lactamase, mediates the acquisition of carbapenem resistance in ST104 Klebsiella pneumoniae isolates from neonates in the intensive care unit of V. Monaldi Hospital in Naples

The emergence of carbapenemase producing Enterobacteriaceae has raised major public health concern. The aim of this study was to investigate the molecular epidemiology and the mechanism of carbapenem resistance acquisition of multidrug-resistant Klebsiella pneumoniae isolates from 20 neonates in the neonatal intensive care unit (NICU) of the V. Monaldi Hospital in Naples, Italy, from April 2015 to March 2016. Genotype analysis by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) identified PFGE type A and subtypes A1 and A2 in 17, 2, and 1 isolates, respectively, and assigned all isolates to sequence type (ST) 104. K. pneumoniae isolates were resistant to all classes of β-lactams including carbapenems, fosfomycin, gentamicin, and trimethoprim-sulfamethoxazole, but susceptible to quinolones, amikacin, and colistin. Conjugation experiments demonstrated that resistance to third-generation cephems and imipenem could be transferred along with an IncA/C plasmid containing the extended spectrum β-lactamase blaSHV -12 and carbapenem-hydrolyzing metallo-β-lactamase blaV IM-1 genes. The plasmid that we called pIncAC_KP4898 was 156,252 bp in size and included a typical IncA/C backbone, which was assigned to ST12 and core genome (cg) ST12.1 using the IncA/C plasmid MLST (PMLST) scheme. pIncAC_KP4898 showed a mosaic structure with blaV IM-1 into a class I integron, blaSHV -12 flanked by IS6 elements, a mercury resistance and a macrolide 2'-phosphotransferase clusters, ant(3″), aph(3″), aacA4, qnrA1, sul1, and dfrA14 conferring resistance to aminoglycosides, quinolones, sulfonamides, and trimethoprim, respectively, several genes predicted to encode transfer functions and proteins involved in DNA transposition. The acquisition of pIncAC_KP4898 carrying blaV IM-1 and blaSHV -12 contributed to the spread of ST104 K. pneumoniae in the NICU of V. Monaldi Hospital in Naples