Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 51
Filtrar
Mais filtros

Base de dados
País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
Mol Ecol ; 33(13): e17411, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38785347

RESUMO

Studying hybrid zones that form between morphologically cryptic taxa offers valuable insights into the mechanisms of cryptic speciation and the evolution of reproductive barriers. Although hybrid zones have long been the focus of evolutionary studies, the awareness of cryptic hybrid zones increased recently due to rapidly growing evidence of biological diversity lacking obvious phenotypic differentiation. The characterization of cryptic hybrid zones with genome-wide analysis is in its early stages and offers new perspectives for studying population admixture and thus the impact of gene flow. In this study, we investigate the population genomics of the Myotis nattereri complex in one of its secondary contact zones, where a putative hybrid zone is formed between two of its cryptic lineages. By utilizing a whole-genome shotgun sequencing approach, we aim to characterize this cryptic hybrid zone in detail. Demographic analysis suggests that the cryptic lineages diverged during the Pliocene, c. 3.6 million years ago. Despite this ancient separation, the populations in the contact zone exhibit mitochondrial introgression and a considerable amount of mixing in nuclear genomes. The genomic structure of the populations corresponds to geographic locations and the genomic admixture changes along a geographic gradient. These findings suggest that there is no effective hybridization barrier between both lineages, nevertheless, their population structure is shaped by dispersal barriers. Our findings highlight how such deeply diverged cryptic lineages can still readily hybridize in secondary contact.


Assuntos
Quirópteros , Fluxo Gênico , Especiação Genética , Genética Populacional , Hibridização Genética , Animais , Quirópteros/genética , Quirópteros/classificação , DNA Mitocondrial/genética , Introgressão Genética
2.
Soft Matter ; 19(25): 4772-4779, 2023 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-37318232

RESUMO

The number and strength of mechanical connections of cells to their local environment can be indicative of their migration and invasion potential. Gaining direct access to the mechanical properties of individual connections and bringing them into a relationship with the state of disease, however, is a formidable task. Here, we present a method to directly sense focal adhesions and cell-cell contacts with a force sensor to quantify the lateral forces of their anchoring points. We found local lateral forces of 1.0-1.5 nN for focal adhesions and slightly higher values at the interfaces between cells where cell-cell contacts are located. Interestingly, a modified surface layer was observed exhibiting considerably reduced tip friction directly next to the area of a retracting cell edge on the substrate. We expect that this technique can improve the understanding of the relationship between mechanical properties of cell connections and the pathological state of cells in the future.


Assuntos
Adesões Focais , Junções Intercelulares , Fenômenos Mecânicos , Torção Mecânica , Análise Espectral , Adesão Celular
3.
Blood ; 132(9): 948-961, 2018 08 30.
Artigo em Inglês | MEDLINE | ID: mdl-29967129

RESUMO

Genomic events associated with poor outcome in chronic myeloid leukemia (CML) are poorly understood. We performed whole-exome sequencing, copy-number variation, and/or RNA sequencing for 65 patients to discover mutations at diagnosis and blast crisis (BC). Forty-six patients with chronic-phase disease with the extremes of outcome were studied at diagnosis. Cancer gene variants were detected in 15 (56%) of 27 patients with subsequent BC or poor outcome and in 3 (16%) of 19 optimal responders (P = .007). Frequently mutated genes at diagnosis were ASXL1, IKZF1, and RUNX1 The methyltransferase SETD1B was a novel recurrently mutated gene. A novel class of variant associated with the Philadelphia (Ph) translocation was detected at diagnosis in 11 (24%) of 46 patients comprising fusions and/or rearrangement of genes on the translocated chromosomes, with evidence of fragmentation, inversion, and imperfect sequence reassembly. These were more frequent at diagnosis in patients with poor outcome: 9 (33%) of 27 vs 2 (11%) of 19 optimal responders (P = .07). Thirty-nine patients were tested at BC, and all had cancer gene variants, including ABL1 kinase domain mutations in 58%. However, ABL1 mutations cooccurred with other mutated cancer genes in 89% of cases, and these predated ABL1 mutations in 62% of evaluable patients. Gene fusions not associated with the Ph translocation occurred in 42% of patients at BC and commonly involved fusion partners that were known cancer genes (78%). Genomic analysis revealed numerous relevant variants at diagnosis in patients with poor outcome and all patients at BC. Future refined biomarker testing of specific variants will likely provide prognostic information to facilitate a risk-adapted therapeutic approach.


Assuntos
Biomarcadores Tumorais/genética , Genômica , Leucemia Mielogênica Crônica BCR-ABL Positiva , Proteínas de Neoplasias/genética , Cromossomo Filadélfia , Translocação Genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Intervalo Livre de Doença , Feminino , Seguimentos , Humanos , Leucemia Mielogênica Crônica BCR-ABL Positiva/diagnóstico , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/mortalidade , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Taxa de Sobrevida
4.
Arch Toxicol ; 94(1): 151-171, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31712839

RESUMO

The first in vitro tests for developmental toxicity made use of rodent cells. Newer teratology tests, e.g. developed during the ESNATS project, use human cells and measure mechanistic endpoints (such as transcriptome changes). However, the toxicological implications of mechanistic parameters are hard to judge, without functional/morphological endpoints. To address this issue, we developed a new version of the human stem cell-based test STOP-tox(UKN). For this purpose, the capacity of the cells to self-organize to neural rosettes was assessed as functional endpoint: pluripotent stem cells were allowed to differentiate into neuroepithelial cells for 6 days in the presence or absence of toxicants. Then, both transcriptome changes were measured (standard STOP-tox(UKN)) and cells were allowed to form rosettes. After optimization of staining methods, an imaging algorithm for rosette quantification was implemented and used for an automated rosette formation assay (RoFA). Neural tube toxicants (like valproic acid), which are known to disturb human development at stages when rosette-forming cells are present, were used as positive controls. Established toxicants led to distinctly different tissue organization and differentiation stages. RoFA outcome and transcript changes largely correlated concerning (1) the concentration-dependence, (2) the time dependence, and (3) the set of positive hits identified amongst 24 potential toxicants. Using such comparative data, a prediction model for the RoFA was developed. The comparative analysis was also used to identify gene dysregulations that are particularly predictive for disturbed rosette formation. This 'RoFA predictor gene set' may be used for a simplified and less costly setup of the STOP-tox(UKN) assay.


Assuntos
Células-Tronco Neurais/efeitos dos fármacos , Transtornos do Neurodesenvolvimento/induzido quimicamente , Neurotoxinas/farmacologia , Formação de Roseta/métodos , Testes de Toxicidade/métodos , Diferenciação Celular/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Células-Tronco Neurais/citologia , Células-Tronco Neurais/fisiologia , Análise de Sequência com Séries de Oligonucleotídeos , Fatores de Tempo
5.
Molecules ; 24(2)2019 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-30658515

RESUMO

The preparation of highly ordered colloidal architectures has attracted significant attention and is a rapidly growing field for various applications, e.g., sensors, absorbers, and membranes. A promising technique for the preparation of elastomeric inverse opal films relies on tailored core/shell particle architectures and application of the so-called melt-shear organization technique. Within the present work, a convenient route for the preparation of core/shell particles featuring highly fluorinated shell materials as building blocks is described. As particle core materials, both organic or inorganic (SiO2) particles can be used as a template, followed by a semi-continuous stepwise emulsion polymerization for the synthesis of the soft fluoropolymer shell material. The use of functional monomers as shell-material offers the possibility to create opal and inverse opal films with striking optical properties according to Bragg's law of diffraction. Due to the presence of fluorinated moieties, the chemical resistance of the final opals and inverse opals is increased. The herein developed fluorine-containing particle-based films feature a low surface energy for the matrix material leading to good hydrophobic properties. Moreover, the low refractive index of the fluoropolymer shell compared to the core (or voids) led to excellent optical properties based on structural colors. The herein described fluoropolymer opals and inverse opals are expected to pave the way toward novel functional materials for application in fields of coatings and optical sensors.


Assuntos
Elastômeros/química , Flúor/química , Polímeros/química , Difusão Dinâmica da Luz , Hidrodinâmica , Interações Hidrofóbicas e Hidrofílicas , Polímeros/síntese química , Solventes/química , Espectrofotometria Ultravioleta
6.
Adv Anat Embryol Cell Biol ; 219: 179-97, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27207367

RESUMO

The open analytics platform KNIME is a modular environment that enables easy visual assembly and interactive execution of workflows. KNIME is already widely used in various areas of research, for instance in cheminformatics or classical data analysis. In this tutorial the KNIME Image Processing Extension is introduced, which adds the capabilities to process and analyse huge amounts of images. In combination with other KNIME extensions, KNIME Image Processing opens up new possibilities for inter-domain analysis of image data in an understandable and reproducible way.


Assuntos
Algoritmos , Processamento de Imagem Assistida por Computador/estatística & dados numéricos , Microscopia de Fluorescência/métodos , Software , Animais , Humanos , Processamento de Imagem Assistida por Computador/métodos , Microscopia de Fluorescência/instrumentação , Fluxo de Trabalho
7.
Genes Chromosomes Cancer ; 54(12): 762-70, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26355392

RESUMO

In eosinophilia-associated myeloproliferative neoplasms (MPN-eo), constitutive activation of protein tyrosine kinases (TK) as consequence of translocations, inversions, or insertions and creation of TK fusion genes is recurrently observed. The most commonly involved TK and their potential TK inhibitors include PDGFRA at 4q12 or PDGFRB at 5q33 (imatinib), FGFR1 at 8p11 (ponatinib), and JAK2 at 9p24 (ruxolitinib). We here report the identification of three new PDGFRB fusion genes in three male MPN-eo patients: MPRIP-PDGFRB in a case with t(5;17)(q33;p11), CPSF6-PDGFRB in a case with t(5;12)(q33;q15), and GOLGB1-PDGFRB in a case with t(3;5)(q13;q33). The fusion proteins identified by 5'-rapid amplification of cDNA ends polymerase chain reaction (PCR) or DNA-based long distance inverse PCR are predicted to contain the TK domain of PDGFRB. The partner genes contain domains like coiled-coil structures, which are likely to cause dimerization and activation of the TK. In all patients, imatinib induced rapid and durable complete remissions.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Eosinofilia/genética , Fusão Gênica , Proteínas de Membrana/genética , Transtornos Mieloproliferativos/genética , Receptor beta de Fator de Crescimento Derivado de Plaquetas/genética , Translocação Genética , Fatores de Poliadenilação e Clivagem de mRNA/genética , Idoso , Idoso de 80 Anos ou mais , Antineoplásicos/uso terapêutico , Cromossomos Humanos Par 12/genética , Cromossomos Humanos Par 17/genética , Cromossomos Humanos Par 3/genética , Cromossomos Humanos Par 5/genética , Análise Citogenética , Eosinofilia/tratamento farmacológico , Eosinofilia/patologia , Proteínas da Matriz do Complexo de Golgi , Humanos , Mesilato de Imatinib/uso terapêutico , Hibridização in Situ Fluorescente , Masculino , Pessoa de Meia-Idade , Transtornos Mieloproliferativos/tratamento farmacológico , Transtornos Mieloproliferativos/patologia , Reação em Cadeia da Polimerase , Indução de Remissão
8.
J Virol ; 88(24): 14207-21, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25275125

RESUMO

UNLABELLED: Murine cells exhibit a profound block to HIV-1 virion production that was recently mapped to a species-specific structural attribute of the murine version of the chromosomal region maintenance 1 (mCRM1) nuclear export receptor and rescued by the expression of human CRM1 (hCRM1). In human cells, the HIV-1 Rev protein recruits hCRM1 to intron-containing viral mRNAs encoding the Rev response element (RRE), thereby facilitating viral late gene expression. Here we exploited murine 3T3 fibroblasts as a gain-of-function system to study hCRM1's species-specific role in regulating Rev's effector functions. We show that Rev is rapidly exported from the nucleus by mCRM1 despite only weak contributions to HIV-1's posttranscriptional stages. Indeed, Rev preferentially accumulates in the cytoplasm of murine 3T3 cells with or without hCRM1 expression, in contrast to human HeLa cells, where Rev exhibits striking en masse transitions between the nuclear and cytoplasmic compartments. Efforts to bias Rev's trafficking either into or out of the nucleus revealed that Rev encoding a second CRM1 binding domain (Rev-2xNES) or Rev-dependent viral gag-pol mRNAs bearing tandem RREs (GP-2xRRE), rescue virus particle production in murine cells even in the absence of hCRM1. Combined, these results suggest a model wherein Rev-associated nuclear export signals cooperate to regulate the number or quality of CRM1's interactions with viral Rev/RRE ribonucleoprotein complexes in the nucleus. This mechanism regulates CRM1-dependent viral gene expression and is a determinant of HIV-1's capacity to produce virions in nonhuman cell types. IMPORTANCE: Cells derived from mice and other nonhuman species exhibit profound blocks to HIV-1 replication. Here we elucidate a block to HIV-1 gene expression attributable to the murine version of the CRM1 (mCRM1) nuclear export receptor. In human cells, hCRM1 regulates the nuclear export of viral intron-containing mRNAs through the activity of the viral Rev adapter protein that forms a multimeric complex on these mRNAs prior to recruiting hCRM1. We demonstrate that Rev-dependent gene expression is poor in murine cells despite the finding that, surprisingly, the bulk of Rev interacts efficiently with mCRM1 and is rapidly exported from the nucleus. Instead, we map the mCRM1 defect to the apparent inability of this factor to engage Rev multimers in the context of large viral Rev/RNA ribonucleoprotein complexes. These findings shed new light on HIV-1 gene regulation and could inform the development of novel antiviral strategies that target viral gene expression.


Assuntos
Regulação Viral da Expressão Gênica , HIV-1/fisiologia , Carioferinas/metabolismo , Sinais de Exportação Nuclear , Receptores Citoplasmáticos e Nucleares/metabolismo , Tropismo Viral , Produtos do Gene rev do Vírus da Imunodeficiência Humana/genética , Produtos do Gene rev do Vírus da Imunodeficiência Humana/metabolismo , Animais , Linhagem Celular , Fibroblastos/virologia , HIV-1/genética , Humanos , Camundongos , Proteína Exportina 1
9.
Ann Hematol ; 94(12): 2015-24, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26385387

RESUMO

Major route additional cytogenetic aberrations (ACA) at diagnosis of chronic myeloid leukaemia (CML) indicate an increased risk of progression and shorter survival. Since major route ACA are almost always unbalanced, it is unclear whether other unbalanced ACA at diagnosis also confer an unfavourable prognosis. On the basis of 1348 Philadelphia chromosome-positive chronic phase patients of the randomized CML study IV, we examined the impact of unbalanced minor route ACA at diagnosis versus major route ACA on prognosis. At diagnosis, 1175 patients (87.2 %) had a translocation t(9;22)(q34;q11) and 74 (5.5 %) a variant translocation t(v;22) only, while a loss of the Y chromosome (-Y) was present in addition in 44 (3.3 %), balanced or unbalanced minor route ACA each in 17 (1.3 %) and major route ACA in 21 (1.6 %) cases. Patients with unbalanced minor route ACA had no significantly different cumulative incidences of complete cytogenetic remission or major molecular remission and no significantly different progression-free survival (PFS) or overall survival (OS) than patients with t(9;22), t(v;22), -Y and balanced minor route karyotypes. In contrast, patients with major route ACA had a shorter OS and PFS than all other groups (all pairwise comparisons to each of the other groups: p ≤ 0.015). Five-year survival probabilities were for t(9;22) 91.4 % (95 % CI 89.5-93.1), t(v; 22) 87 % (77.2-94.3), -Y 89.0 % (76.7-97.0), balanced 100 %, unbalanced minor route 92.3 % (72.4-100) and major route 52.2 % (28.2-75.5). We conclude that only major route, but not balanced or unbalanced minor route ACA at diagnosis, has a negative impact on prognosis of CML.


Assuntos
Cariótipo Anormal , Leucemia Mielogênica Crônica BCR-ABL Positiva , Cromossomo Filadélfia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Intervalo Livre de Doença , Feminino , Humanos , Cariotipagem , Leucemia Mielogênica Crônica BCR-ABL Positiva/diagnóstico , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/mortalidade , Masculino , Pessoa de Meia-Idade , Taxa de Sobrevida
10.
Haematologica ; 99(9): 1441-7, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24837466

RESUMO

The vast majority of chronic myeloid leukemia patients express a BCR-ABL1 fusion gene mRNA encoding a 210 kDa tyrosine kinase which promotes leukemic transformation. A possible differential impact of the corresponding BCR-ABL1 transcript variants e13a2 ("b2a2") and e14a2 ("b3a2") on disease phenotype and outcome is still a subject of debate. A total of 1105 newly diagnosed imatinib-treated patients were analyzed according to transcript type at diagnosis (e13a2, n=451; e14a2, n=496; e13a2+e14a2, n=158). No differences regarding age, sex, or Euro risk score were observed. A significant difference was found between e13a2 and e14a2 when comparing white blood cells (88 vs. 65 × 10(9)/L, respectively; P<0.001) and platelets (296 vs. 430 × 10(9)/L, respectively; P<0.001) at diagnosis, indicating a distinct disease phenotype. No significant difference was observed regarding other hematologic features, including spleen size and hematologic adverse events, during imatinib-based therapies. Cumulative molecular response was inferior in e13a2 patients (P=0.002 for major molecular response; P<0.001 for MR4). No difference was observed with regard to cytogenetic response and overall survival. In conclusion, e13a2 and e14a2 chronic myeloid leukemia seem to represent distinct biological entities. However, clinical outcome under imatinib treatment was comparable and no risk prediction can be made according to e13a2 versus e14a2 BCR-ABL1 transcript type at diagnosis. (clinicaltrials.gov identifier:00055874).


Assuntos
Antineoplásicos/uso terapêutico , Benzamidas/uso terapêutico , Proteínas de Fusão bcr-abl/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Piperazinas/uso terapêutico , Pirimidinas/uso terapêutico , RNA Mensageiro/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Processamento Alternativo , Plaquetas/efeitos dos fármacos , Plaquetas/patologia , Monitoramento de Medicamentos , Feminino , Proteínas de Fusão bcr-abl/metabolismo , Genótipo , Humanos , Mesilato de Imatinib , Leucemia Mielogênica Crônica BCR-ABL Positiva/mortalidade , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , Leucócitos/efeitos dos fármacos , Leucócitos/patologia , Masculino , Pessoa de Meia-Idade , Fenótipo , RNA Mensageiro/metabolismo , Indução de Remissão , Análise de Sobrevida , Resultado do Tratamento
11.
Langmuir ; 30(1): 369-79, 2014 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-24364647

RESUMO

We present a strategy toward controlled polymer density in mesopores by specifically adjusting the local amount of polymerization initiator at the pore wall. The polymerization initiator concentration as well as the polymer functionalization has a direct impact on mesoporous membrane properties such as ionic permselectivity. Mesoporous silica-based thin films were prepared with specifically adjusted amount of polymerization initiator (4-(3-triethoxysilyl)propoxybenzophenone (BPSilane)) or initiator binding functions ((3-aminopropyl)triethoxysilane (APTES)), directly and homogeneously incorporated into the silica wall pursuing a sol-gel-based co-condensation approach. The amount of polymerization initiator was adjusted by varying its concentration in the sol-gel precursor solution. The surface chemistry, porosity, pore accessibility, and reactivity of the surface functional groups were investigated by using infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray reflectometry, ellipsometry, atomic force microscopy, and transmission electron microscopy. We could gradually modify the amount of reactive polymerization initiators in these mesoporous membranes. Mesopores were maintained for APTES containing films for all tested ratios up to 25 mol % and for BPSilane containing films up to 15 mol %. These films showed accessible and charge-dependent ionic permselectivity and an increasing degree of functionalization with increasing precursor ratio. This approach can directly result in control of polymer grafting density in mesoporous films and thus has a direct impact on applications such as the control of ionic transport through mesoporous silica membranes.

12.
Retrovirology ; 10: 111, 2013 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-24156545

RESUMO

BACKGROUND: In response to viral infections, interferons induce the transcription of several hundred genes in mammalian cells. Specific antiviral functions, however, have only been attributed to a few of them. 90K/LGALS3BP has been reported to be an interferon-stimulated gene that is upregulated in individuals with cancer or HIV-1 infection. RESULTS: Here, we show that 90K expression dose-dependently decreased the particle infectivity of HIV-1 progeny. The lower infectivity of released particles correlated with reduced virion incorporation of mature envelope glycoproteins gp120 and gp41. Further, proteolytic processing of the gp160 precursor and surface expression of gp120 in the producer cell were impaired in the presence of 90K expression. In contrast, expression of Gag, Nef and Vpu, and virus release were not grossly affected by 90K expression. 90K-imposed restriction occurred in the absence of direct interaction of 90K with HIV-1 Env or entrapment of Env in the ER. The cell-associated, but not the secreted species of 90K, mediated the antiviral effect. A truncated version of human 90K, solely consisting of the two intermediate domains, displayed a similar antiviral activity as the full-length wildtype 90K, indicating that the N-terminal SRCR-like domain and the C-terminal domain are dispensable for 90K's antiviral activity. The murine homolog of 90K, CypCAP (Cyclophilin C-associated protein), neither modulated particle infectivity of HIV-1 nor lowered the virion incorporation of mature gp120, suggesting a species-specific mode of action. 90K was expressed at basal levels in TZM-bl cells and in primary macrophages, and at low levels in CD4⁺ T-cells and PBMCs. 90K's susceptibility to IFN-mediated stimulation of expression was cell type-specific. siRNA-mediated knockdown of 90K in TZM-bl cells and primary macrophages enhanced the incorporation of Env glycoproteins into progeny virions, boosted the particle infectivity of released HIV-1, and accelerated HIV-1 spread. Conversely, treatment of HIV-1 infected macrophages with IFN-α induced 90K expression and lowered the particle infectivity of HIV-1. CONCLUSIONS: Thus, 90K constitutes a novel antiviral factor that reduces the particle infectivity of HIV-1, involving interference with the maturation and incorporation of HIV-1 Env molecules into virions.


Assuntos
Antígenos de Neoplasias/imunologia , Biomarcadores Tumorais/imunologia , Proteínas de Transporte/imunologia , Glicoproteínas/imunologia , HIV-1/imunologia , HIV-1/fisiologia , Interferons/imunologia , Montagem de Vírus , Linhagem Celular , Humanos , Processamento de Proteína Pós-Traducional , Liberação de Vírus , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologia , Produtos do Gene env do Vírus da Imunodeficiência Humana/metabolismo
13.
Mol Ecol ; 22(15): 4055-70, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23889545

RESUMO

The demographic history of Rhinolophus hipposideros (lesser horseshoe bat) was reconstructed across its European, North African and Middle-Eastern distribution prior to, during and following the most recent glaciations by generating and analysing a multimarker data set. This data set consisted of an X-linked nuclear intron (Bgn; 543 bp), mitochondrial DNA (cytb-tRNA-control region; 1630 bp) and eight variable microsatellite loci for up to 373 individuals from 86 localities. Using this data set of diverse markers, it was possible to determine the species' demography at three temporal stages. Nuclear intron data revealed early colonization into Europe from the east, which pre-dates the Quaternary glaciations. The mtDNA data supported multiple glacial refugia across the Mediterranean, the largest of which were found in the Ibero-Maghreb region and an eastern location (Anatolia/Middle East)-that were used by R. hipposideros during the most recent glacial cycles. Finally, microsatellites provided the most recent information on these species' movements since the Last Glacial Maximum and suggested that lineages that had diverged into glacial refugia, such as in the Ibero-Maghreb region, have remained isolated. These findings should be used to inform future conservation management strategies for R. hipposideros and show the power of using a multimarker data set for phylogeographic studies.


Assuntos
Quirópteros/genética , DNA Mitocondrial/genética , Repetições de Microssatélites/genética , Animais , Sequência de Bases , Biglicano/genética , Citocromos b/genética , Europa (Continente) , Evolução Molecular , Frequência do Gene , Marcadores Genéticos/genética , Variação Genética , Haplótipos/genética , Filogeografia , Análise de Sequência de DNA
14.
Org Biomol Chem ; 11(14): 2258-65, 2013 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-23250285

RESUMO

Cube octameric silsesquioxanes (COSS) are among the smallest nanoparticles known to date with a diameter of only 0.7 nm. We describe a COSS-based delivery system which allows for the drug targeting in human cells. It comprises a siloxane core with seven pendant aminopropyl groups and a fluorescently labeled peptidic ligand attached to one cage corner via a reversible disulfide bond to ensure its intracellular release. Bimodal amplitude-modulated atomic force microscopy (AFM) experiments revealed the formation of dendritic COSS structures by a self-assembly of single particles on negatively charged surfaces. Nuclear targeting was demonstrated in HeLa cells by selective binding of released p21(Cip1/Waf1)-derived cargo peptide to PCNA, a protein involved in DNA replication and repair.


Assuntos
Sistemas de Liberação de Medicamentos , Compostos de Organossilício/química , Peptídeos/metabolismo , Compostos de Amônio Quaternário/química , Cromatografia Líquida de Alta Pressão , Células HeLa , Humanos , Microscopia de Força Atômica , Estrutura Molecular , Nanopartículas/química , Tamanho da Partícula , Peptídeos/química , Peptídeos/genética , Antígeno Nuclear de Célula em Proliferação/química , Antígeno Nuclear de Célula em Proliferação/genética , Antígeno Nuclear de Célula em Proliferação/metabolismo
15.
Nanoscale ; 15(36): 15008-15026, 2023 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-37668423

RESUMO

Discovering tools to prevent cancer progression requires understanding the fundamental differences between normal and cancer cells. More than a decade ago, atomic force microscopy (AFM) revealed cancer cells' softer body compared to their healthy counterparts. Here, we investigated the mechanism underlying the softening of cancerous cells in comparison with their healthy counterparts based on AFM high resolution stiffness tomography and 3D confocal microscopy. We showed microtubules (MTs) network in invasive ductal carcinoma cell cytoskeleton is basally located and segmented for around 400 nm from the cell periphery. Additionally, the cytoskeleton scaffolding protein plectin exhibits a mis-localization from the cytoplasm to the surface of cells in the carcinoma which justifies the dissociation of the MT network from the cell's cortex. Furthermore, the assessment of MTs' persistence length using a worm-like-chain (WLC) model in high resolution AFM images showed lower persistence length of the single MTs in ductal carcinoma compared to that in the normal state. Overall, these tuned mechanics support the invasive cells to ascertain more flexibility under compressive forces in small deformations. These data provide new insights into the structural origins of cancer aids in progression.


Assuntos
Carcinoma Ductal , Humanos , Carcinoma Ductal/metabolismo , Citoplasma/metabolismo , Citoesqueleto/metabolismo , Hidrolases/metabolismo , Microtúbulos/metabolismo
16.
Animals (Basel) ; 13(15)2023 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-37570338

RESUMO

Bats of Greece have been studied since the second half of the 19th century. Their distribution and ecology, however, remain poorly understood. Conservation efforts for the protection of the roosting and foraging habitats of their populations in Greece are limited. To date, 35 bat species have been recorded from Greece. Four species (Eptesicus anatolicus, Plecotus auritus, Myotis brandtii and Rousettus aegyptiacus) have a limited distribution in the country and the presence of one species (Myotis mystacinus) requires verification. The present study summarises all existing knowledge and adds several hundred new records on the distribution of bats of Greece. Additionally, it provides a summary of new insights on various aspects of their roosting ecology, foraging habitat use, altitudinal distribution, winter activity and landscape characteristics around major roosts. Finally, it discusses the current research and conservation needs of Greek bats.

17.
Materials (Basel) ; 16(16)2023 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-37629794

RESUMO

The fabrication of nanocomposites containing magnetic nanoparticles is gaining interest as a model for application in small electronic devices. The self-assembly of block copolymers (BCPs) makes these materials ideal for use as a soft matrix to support the structural ordering of the nanoparticles. In this work, a high-molecular-weight polystyrene-b-poly(methyl methacrylate) block copolymer (PS-b-PMMA) was synthesized through anionic polymerization. The influence of the addition of different ratios of PMMA-coated FePt nanoparticles (NPs) on the self-assembled morphology was investigated using transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). The self-assembly of the NPs inside the PMMA phase at low particle concentrations was analyzed statistically, and the negative effect of higher particle ratios on the lamellar BCP morphology became visible. The placement of the NPs inside the PMMA phase was also compared to theoretical descriptions. The magnetic addressability of the FePt nanoparticles inside the nanocomposite films was finally analyzed using bimodal magnetic force microscopy and proved the magnetic nature of the nanoparticles inside the microphase-separated BCP films.

18.
Circ Res ; 107(1): 45-55, 2010 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-20466982

RESUMO

RATIONALE: Angiogenesis is regulated by the small GTPase Rac1. The ELMO1/DOCK180 complex forms a guanine nucleotide exchange factor for Rac1, regulating its activation during cell migration in different biological systems. OBJECTIVE: To investigate the function of ELMO1/DOCK180 in vascular development. METHODS AND RESULTS: In situ hybridization studies for elmo1 identified a vascular and neuronal expression in zebrafish. Morpholino-based expression silencing of elmo1 severely impaired the formation of the vasculature, including intersomitic vessels, the dorsal longitudinal anastomotic vessel, the parachordal vessel, and the development of the thoracic duct in tg(fli1:EGFP) embryos. Mechanistically, we identified Netrin-1 and its receptor Unc5B as upstream activators of the ELMO1/DOCK180 complex, regulating its functional interaction and leading to Rac1 activation in endothelial cells and vessel formation in zebrafish. CONCLUSIONS: Our data have identified a novel signaling cascade regulating vasculature formation in zebrafish.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/fisiologia , Vasos Sanguíneos/embriologia , Proteínas de Peixe-Zebra/fisiologia , Proteínas rac1 de Ligação ao GTP/fisiologia , Sequência de Aminoácidos , Animais , Animais Geneticamente Modificados , Vasos Sanguíneos/citologia , Bovinos , Linhagem Celular , Células Endoteliais/citologia , Células Endoteliais/fisiologia , Humanos , Dados de Sequência Molecular , Filogenia , Peixe-Zebra , Proteínas rac de Ligação ao GTP
19.
Org Biomol Chem ; 10(31): 6287-93, 2012 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-22733169

RESUMO

Polyhedral silsesquioxanes are considered valuable conjugation scaffolds. Nevertheless, only a few examples of silsesquioxane-assembled peptide oligomers have been reported to date. We developed a new bioorthogonal cube-octameric silsesquioxane (COSS) scaffold bearing eight aminooxy coupling sites allowing for the conjugation of diverse peptides via oxime ligation. We found that the coupling efficacy depends on the ligand in view of steric hindrance and electrostatic repulsion. For the first time scaffold-based conjugation of cystine-knot miniproteins having a backbone of about thirty amino acids was successfully accomplished without loss of bioactivity. Atomic force microscopy (AFM) provided further knowledge on the size of COSS verifying them as picoscaffolds growing upon bioconjugation to nano-dimension.


Assuntos
Nanopartículas/química , Compostos de Organossilício/química , Peptídeos/química , Aldeídos/química , Sequência de Aminoácidos , Microscopia de Força Atômica , Modelos Moleculares , Dados de Sequência Molecular , Nanopartículas/ultraestrutura , Oximas/química
20.
Sci Rep ; 12(1): 8981, 2022 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-35643777

RESUMO

Combined in-plane and out-of-plane multifrequency atomic force microscopy techniques have been demonstrated to be important tools to decipher spatial differences of sample surfaces at the atomic scale. The analysis of physical properties perpendicular to the sample surface is routinely achieved from flexural cantilever oscillations, whereas the interpretation of in-plane sample properties via force microscopy is still challenging. Besides the torsional oscillation, there is the additional option to exploit the lateral oscillation of the cantilever for in-plane surface analysis. In this study, we used different multifrequency force microscopy approaches to attain better understanding of the interactions between a super-sharp tip and an HOPG surface focusing on the discrimination between friction and shear forces. We found that the lateral eigenmode is suitable for the determination of the shear modulus whereas the torsional eigenmode provides information on local friction forces between tip and sample. Based on the results, we propose that the full set of elastic constants of graphite can be determined from combined in-plane and out-of-plane multifrequency atomic force microscopy if ultrasmall amplitudes and high force constants are used.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA