RESUMO
Ancient DNA analysis has revealed an involvement of the bacterial pathogen Yersinia pestis in several historical pandemics, including the second plague pandemic (Europe, mid-14(th) century Black Death until the mid-18(th) century AD). Here we present reconstructed Y. pestis genomes from plague victims of the Black Death and two subsequent historical outbreaks spanning Europe and its vicinity, namely Barcelona, Spain (1300-1420 cal AD), Bolgar City, Russia (1362-1400 AD), and Ellwangen, Germany (1485-1627 cal AD). Our results provide support for (1) a single entry of Y. pestis in Europe during the Black Death, (2) a wave of plague that traveled toward Asia to later become the source population for contemporary worldwide epidemics, and (3) the presence of an historical European plague focus involved in post-Black Death outbreaks that is now likely extinct.
Assuntos
Pandemias/história , Peste/história , Peste/microbiologia , Yersinia pestis/genética , Ásia/epidemiologia , Osso e Ossos/microbiologia , DNA Bacteriano/genética , Reservatórios de Doenças , Europa (Continente)/epidemiologia , Genoma Bacteriano , Genótipo , Sequenciamento de Nucleotídeos em Larga Escala , História do Século XV , História do Século XVI , História do Século XVII , História do Século XVIII , História Medieval , Humanos , Epidemiologia Molecular , Filogenia , Peste/epidemiologia , Dente/microbiologia , Yersinia pestis/isolamento & purificaçãoRESUMO
Functionalized living cells are regarded as effective tools in directed cell delivery and tissue engineering. Here we report the facile functionalization of viable isolated HeLa cells with superparamagnetic cationic nanoparticles via a single-step biocompatible process. Nanoparticles are localized on the cellular membranes and do not penetrate into the cytoplasm. The magnetically responsive cells are viable and able to colonize and grow on substrates. Magnetically facilitated microorganization of functionalized cells into viable living clusters is demonstrated. We believe that the technique described here may find a number of potential applications in cell-based therapies and in development of whole-cell biosensors.
Assuntos
Materiais Biocompatíveis/química , Compostos Férricos/química , Magnetismo , Nanopartículas/química , Técnicas Biossensoriais , Cátions/química , Membrana Celular/metabolismo , Sobrevivência Celular , Células Cultivadas , Citoplasma/metabolismo , Compostos Férricos/síntese química , Células HeLa , Humanos , Microscopia de Fluorescência , Tamanho da Partícula , Propriedades de SuperfícieRESUMO
Green algae are a promising platform for the development of biosensors and bioelectronic devices. Here we report a reliable single-step technique for the functionalisation of living unicellular green algae Chlorella pyrenoidosa with biocompatible 15 nm superparamagnetic nanoparticles stabilised with poly(allylamine hydrochloride). The magnetised algae cells can be manipulated and immobilised using external permanent magnets. The distribution of the nanoparticles on the cell walls of C. pyrenoidosa was studied by optical and fluorescence microscopy, TEM, SEM and EDX spectroscopy. The viability and the magnetic properties of the magnetised algae are studied in comparison with the native cells. The technique may find a number of potential applications in biotechnology and bioelectronics.
Assuntos
Chlorella/citologia , Magnetismo , Nanopartículas/química , Polímeros/química , Materiais Biocompatíveis/química , Técnicas Biossensoriais , Teste de MateriaisRESUMO
Here we report the fabrication of magnetically responsive calcium carbonate microcrystals produced by coprecipitation of calcium carbonate in the presence of citrate-stabilized iron oxide nanoparticles. We demonstrate that the calcite microcrystals obtained possess superparamagnetic properties due to incorporated magnetite nanoparticles and can be manipulated by an external magnetic field. The microcrystals doped with magnetic nanoparticles were utilized as templates for the fabrication of hollow polyelectrolyte microcapsules, which retain the magnetic properties of the sacrificial cores and might be spatially manipulated using a permanent magnet, thus providing the magnetic-field-facilitated delivery and separation of materials templated on magnetically responsive calcite microcrystals.
