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Barbieri C.,MPI for Evolutionary Anthropology | Barbieri C.,University of Bologna | Vicente M.,University of Porto | Vicente M.,Investigacao e Servicos em Ciencias Biologicas Lda | And 7 more authors.
PLoS ONE | Year: 2014

Bantu speech communities expanded over large parts of sub-Saharan Africa within the last 4000-5000 years, reaching different parts of southern Africa 1200-2000 years ago. The Bantu languages subdivide in several major branches, with languages belonging to the Eastern and Western Bantu branches spreading over large parts of Central, Eastern, and Southern Africa. There is still debate whether this linguistic divide is correlated with a genetic distinction between Eastern and Western Bantu speakers. During their expansion, Bantu speakers would have come into contact with diverse local populations, such as the Khoisan hunter-gatherers and pastoralists of southern Africa, with whom they may have intermarried. In this study, we analyze complete mtDNA genome sequences from over 900 Bantu-speaking individuals from Angola, Zambia, Namibia, and Botswana to investigate the demographic processes at play during the last stages of the Bantu expansion. Our results show that most of these Bantu-speaking populations are genetically very homogenous, with no genetic division between speakers of Eastern and Western Bantu languages. Most of the mtDNA diversity in our dataset is due to different degrees of admixture with autochthonous populations. Only the pastoralist Himba and Herero stand out due to high frequencies of particular L3f and L3d lineages; the latter are also found in the neighboring Damara, who speak a Khoisan language and were foragers and small-stock herders. In contrast, the close cultural and linguistic relatives of the Herero and Himba, the Kuvale, are genetically similar to other Bantu-speakers. Nevertheless, as demonstrated by resampling tests, the genetic divergence of Herero, Himba, and Kuvale is compatible with a common shared ancestry with high levels of drift, while the similarity of the Herero, Himba, and Damara probably reflects admixture, as also suggested by linguistic analyses. Copyright: © 2014 Barbieri et al. Source


Barbieri C.,Max Planck Research Group on Comparative Population Linguistics | Vicente M.,Investigacao e Servicos em Ciencias Biologicas Lda | Vicente M.,University of Porto | Rocha J.,University of Porto | And 3 more authors.
American Journal of Human Genetics | Year: 2013

Among the deepest-rooting clades in the human mitochondrial DNA (mtDNA) phylogeny are the haplogroups defined as L0d and L0k, which are found primarily in southern Africa. These lineages are typically present at high frequency in the so-called Khoisan populations of hunter-gatherers and herders who speak non-Bantu languages, and the early divergence of these lineages led to the hypothesis of ancient genetic substructure in Africa. Here we update the phylogeny of the basal haplogroups L0d and L0k with 500 full mtDNA genome sequences from 45 southern African Khoisan and Bantu-speaking populations. We find previously unreported subhaplogroups and greatly extend the amount of variation and time-depth of most of the known subhaplogroups. Our major finding is the definition of two ancient sublineages of L0k (L0k1b and L0k2) that are present almost exclusively in Bantu-speaking populations from Zambia; the presence of such relic haplogroups in Bantu speakers is most probably due to contact with ancestral pre-Bantu populations that harbored different lineages than those found in extant Khoisan. We suggest that although these populations went extinct after the immigration of the Bantu-speaking populations, some traces of their haplogroup composition survived through incorporation into the gene pool of the immigrants. Our findings thus provide evidence for deep genetic substructure in southern Africa prior to the Bantu expansion that is not represented in extant Khoisan populations. © 2013 The American Society of Human Genetics. Source


Bernacka-Wojcik I.,New University of Lisbon | Aguas H.,New University of Lisbon | Carlos F.F.,New University of Lisbon | Carlos F.F.,Investigacao e Servicos em Ciencias Biologicas Lda | And 8 more authors.
Biotechnology and Bioengineering | Year: 2015

The use of microfluidics platforms combined with the optimal optical properties of gold nanoparticles has found plenty of application in molecular biosensing. This paper describes a bio-microfluidic platform coupled to a non-cross-linking colorimetric gold nanoprobe assay to detect a single nucleotide polymorphism associated with increased risk of obesity fat-mass and obesity-associated (FTO) rs9939609 (Carlos et al., 2014). The system enabled significant discrimination between positive and negative assays using a target DNA concentration of 5ng/μL below the limit of detection of the conventionally used microplate reader (i.e., 15ng/μL) with 10 times lower solution volume (i.e., 3μL). A set of optimization of our previously reported bio-microfluidic platform (Bernacka-Wojcik et al., 2013) resulted in a 160% improvement of colorimetric analysis results. Incorporation of planar microlenses increased 6 times signal-to-loss ratio reaching the output optical fiber improving by 34% the colorimetric analysis of gold nanoparticles, while the implementation of an optoelectronic acquisition system yielded increased accuracy and reduced noise. The microfluidic chip was also integrated with a miniature fiber spectrometer to analyze the assays' colorimetric changes and also the LEDs transmission spectra when illuminating through various solutions. Furthermore, by coupling an optical microscope to a digital camera with a long exposure time (30s), we could visualise the different scatter intensities of gold nanoparticles within channels following salt addition. These intensities correlate well to the expected difference in aggregation between FTO positive (none to small aggregates) and negative samples (large aggregates). © 2015 Wiley Periodicals, Inc. Source


Canovi M.,Istituto di Ricerche Farmacologiche Mario Negri | Markoutsa E.,University of Patras | Lazar A.N.,French Institute of Health and Medical Research | Pampalakis G.,University of Patras | And 10 more authors.
Biomaterials | Year: 2011

Amyloid β (Aβ) aggregates are considered as possible targets for therapy and/or diagnosis of Alzheimer disease (AD), and nanoparticles functionalized with Aβ-specific ligands are considered promising vehicles for imaging probes and therapeutic agents. Herein, we characterized the binding properties of nanoliposomes decorated with an anti-Aβ monoclonal antibody (Aβ-MAb). The Aβ-MAb was obtained in mice by immunization with Aβ antigen followed by hybridoma fusion. Surface Plasmon Resonance (SPR) studies confirmed the very high affinity of purified Aβ-MAb for both Aβ monomers and fibrils (KD = 0.08 and 0.13 nm, respectively). The affinity of the biotinylated Aβ-MAb, used thereafter for liposome decoration, was lower although still in the low nanomolar range (KD = 2.1 and 1.6 nm, respectively). Biotin-streptavidin ligation method was used to decorate nanoliposomes with Aβ-MAb, at different densities. IgG-decorated liposomes were generated by the same methodology, as control. Vesicles were monodisperse with mean diameters 124-134 nm and demonstrated good colloidal stability and integrity when incubated with serum proteins. When studied by SPR, Aβ-MAb-liposomes, but not IgG-liposomes, markedly bound to Aβ monomers and fibrils, immobilized on the chip. KD values (calculated on Aβ-MAb content) were about 0.5 and 2 nm with liposomes at high and low Aβ-MAb density, respectively. Aβ-MAb-liposome binding to Aβ fibrils was additionally confirmed by ultracentrifugation technique, in which interactions occur in solution under physiological conditions. Moreover, Aβ-MAb-liposomes bound amyloid deposits in post-mortem AD brain samples, confirming the potential of these nanoparticles for the diagnosis and therapy of AD. © 2011 Elsevier Ltd. Source


Markoutsa E.,University of Patras | Papadia K.,University of Patras | Clemente C.,Investigacao e Servicos em Ciencias Biologicas Lda | Flores O.,Investigacao e Servicos em Ciencias Biologicas Lda | And 2 more authors.
European Journal of Pharmaceutics and Biopharmaceutics | Year: 2012

Anti-Aβ-MAb (Aβ-MAb)-decorated immunoliposomes (LIP) and dually decorated ones (dd-LIP) with OX-26 and Aβ-MAb were constructed. In both cases, the biotin-streptavidin ligation method was applied. All LIP types were characterized for size distribution, zeta potential, and integrity during incubation with serum proteins. Uptake and transcytosis of both LIP types and control vesicles by human brain endothelial hCMEC/D3 cells were measured. All LIP types had mean diameters below 150-200 nm and low polydispersity. Aβ-MAb-LIP uptake was higher than control PEGylated liposomes, while uptake of dd-LIP was similar to that of OX-26-LIP. Aβ-MAb-LIP and dd-LIP uptake increased significantly when cells were pre-incubated with Aβ1-42 peptides; OX-26-LIP uptake was not modulated. Transcytosis of Aβ-MAb-LIP through monolayers was 2.5 times higher when monolayers were pre-incubated with Aβ1-42. Transport of both probes, FITC-dextran and rhodamine-lipid, was equivalent, indicating that Aβ-MAb-LIP are transferred intact through the BBB model. The Aβ peptide-induced increase in binding (and transport) is regulated by the membrane receptors for Aβ1-42 peptides (RAGE), as proven after blocking RAGE by a specific MAb. Aβ1-42 peptides did not modulate the barrier tightness and integrity, as determined by transendothelial resistance and Lucifer Yellow permeability. Additionally, hCMEC/D3 cell viability was not affected by Aβ peptides or by Aβ-MAb-LIP. © 2012 Elsevier B.V. All rights reserved. Source

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