An 18 S rDNA based molecular phylogeny of the Mysidacea (Crustacea)

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Fabrication and functionalization of PCB gold electrodes suitable for DNA-based electrochemical sensing

The request of high specificity and selectivity sensors suitable for mass production is a constant demand in medical research. For applications in point-of-care diagnostics and therapy, there is a high demand for low cost and rapid sensing platforms. This paper describes the fabrication and functionalization of gold electrodes arrays for the detection of deoxyribonucleic acid (DNA) in printed circuit board (PCB) technology. The process can be implemented to produce efficiently a large number of biosensors. We report an electrolytic plating procedure to fabricate low-density gold microarrays on PCB suitable for electrochemical DNA detection in research fields such as cancer diagnostics or pharmacogenetics, where biosensors are usually targeted to detect a small number of genes. PCB technology allows producing high precision, fast and low cost microelectrodes. The surface of the microarray is functionalized with self-assembled monolayers of mercaptoundodecanoic acid or thiolated DNA. The PCB microarray is tested by cyclic voltammetry in presence of 5 mM of the redox probe K3Fe(CN6) in 0.1 M KCl. The voltammograms prove the correct immobilization of both the alkanethiol systems. The sensor is tested for detecting relevant markers for breast cancer. Results for 5 nM of the target TACSTD1 against the complementary TACSTD1 and non-complementary GRP, MYC, SCGB2A1, SCGB2A2, TOP2A probes show a remarkable detection limit of 0.05 nM and a high specificity

Presence of peritrophic-like membranes in the intestine of three bacteriophagous nematodes (Nematoda : Rhabditida)

Chez trois nématodes Rhabdities, #Caenorhabditis elegans, Panagrolaimus superbus et #Acrobeloides maximus, les analyses ultrastructurales ont démontré la présence d'une membrane prenant naissance à l'extrémité des microvillosités intestinales, et ce sur l'entière longueur de l'intestin. Ces membranes permettent le passage de l'isothiocyanate de fluorescéine, du rouge de méthyle, du rouge neutre et de l'orange d'acridine, mais un passage très limité des molécules de ferritine. Après introduction d'une dose subléthale d'azide de sodium, la lumière intestinale est le siège d'une augmentation de la sécrétion des couches de la membrane. Des colorations #in toto des nématodes avec des lectines provenant de #Solanum tuberosum et #Triticum vulgare$, connues pour leur grande affinité avec la chitine, ont seulement montré une liaison spécifique de la première avec la frange en brosse, et ce chez tous les stades des trois nématodes considérés. Ces résultats révèlent dans l'intestin de trois espèces appartenant à un des plus anciens phylums de métazoaire, la présence de membranes possédant des caractéristiques morphologiques et fonctionnelles rappelant les membranes péritrophiques des insectes. (Résumé d'auteur

Invasive aspergillosis mimicking metastatic lung cancer

In a patient with a medical history of cancer, the most probable diagnosis of an (18)FDG-avid pulmonary mass combined with intracranial abnormalities on brain imaging is metastasized cancer. However, sometimes a differential diagnosis with an infectious cause such as aspergillosis can be very challenging as both cancer and infection are sometimes difficult to distinguish. Pulmonary aspergillosis can present as an infectious pseudotumour with clinical and imaging characteristics mimicking lung cancer. Even in the presence of cerebral lesions, radiological appearance of abscesses can look like brain metastasis. These similarities can cause significant diagnostic difficulties with a subsequent therapeutic delay and a potential adverse outcome. Awareness of this infectious disease that can mimic lung cancer, even in an immunocompetent patient, is important. We report a case of a 65-year-old woman with pulmonary aspergillosis disseminated to the brain mimicking metastatic lung cancer

Disentangling taxonomy within the <i>Rhabditis (Pellioditis) marina</i> (Nematoda, Rhadbitidae) species complex using molecular and morphological tools

Correct taxonomy is a prerequisite for biological research, but currently it is undergoing a serious crisis, resulting in the neglect of many highly diverse groups of organisms. In nematodes, species delimitation remains problematic due to their high morphological variability. Evolutionary approaches using DNA sequences can potentially overcome the problems caused by morphology, but they are also affected by flaws. A holistic approach with a combination of morphological and molecular methods can therefore produce a straightforward delimitation of species. The present study investigates the taxonomic status of some highly divergent mitochondrial haplotypes in the Rhabditis (Pellioditis) marina species complex by using a combination of molecular and morphological tools. We used concordance among phylogenetic trees of three molecular markers (COI, ITS, D2D3) to infer molecular lineages. Subsequently, morphometric data from nearly all lineages were analysed with multivariate techniques. The results showed that highly divergent genotypic clusters were accompanied by morphological differences, and we created a graphical polytomous key for future identifications. This study indisputably demonstrates that R. (P.) marina and R. (P.) mediterranea belong to a huge species complex and that biodiversity in free-living marine nematodes may seriously be underestimated

Phylogeography of the <i>Rhabditis (Pellioditis) marina</i> species complex: evidence for cosmopolitanism, restricted gene flow, recent range expansions and accelerated evolution

The nematode Rhabditis (Pellioditis) marina has a worldwide distribution despite presumably low dispersal abilities. Recent studies on a local scale have illustrated that R. (P.) marina actually consists of several cryptic species which questions its true cosmopolitan distribution. We performed a phylogeographic study to identify micro- and macro-evolutionary processes shaping population structuring and speciation in the R. (P.) marina species complex. The mitochondrial COI gene was screened with the Single Strand Conformation Polymorphism method (SSCP) in 1292 specimens collected from decomposing macroalgae along the coasts of Western Europe, NE America, Mexico, South Africa and Australia. We found evidence for eleven cryptic species within R. (P.) marina that were sympatrically distributed. A strong genetic structuring was observed in all species and a genetic break was observed around the British Isles. A historical signature was present in species PmII showing evidence for two postglacial, northwards orientated expansions and for restricted gene flow with occasional long-distance dispersal. Our data also pointed to a contact zone in the Southern Bight of the North Sea. We found evidence for a true cosmopolitan distribution of nematode species due to occasional long-distance dispersal. In addition, an accelerated COI mutation rate was suggested for R. (P.) marina, which was about ten times higher than the generally applied molecular clock of 2 %. We further hypothesize that the cryptic radiation in R. (P.) marina is largely the result of allopatric speciation, and that the contemporary sympatric distribution results from occasional long-distance dispersal

ENOBIO - First tests of a dry electrophysiology electrode using carbon nanotubes

We describe the development and first tests of Enobio, a dry electrode sensor concept for biopotential applications. In the proposed electrodes, the tip of the electrode is covered with a forest of multi-walled CNTs that can be coated with Ag/AgCl to provide ionic-electronic transduction. The CNT brush-like structure is to penetrate the outer layers of the skin improving electrical contact as well as increae the contact surface area. In this paper, we report the results of the first tests of this concept -- immersion on saline solution and pig skin signal detection. These indicate performance on a par with state of the art research-oriented wet electrodes.Comment: Submitted and accepted at the 28th IEEE EMBS International Conference, New York City, August 31st-September 3rd, 2006. Figures updated with proper filtering and averagin

Mitochondrial DNA variation and cryptic speciation within the free-living marine nematode <i>Pellioditis marina</i>

An inverse correlation between dispersal ability and genetic differentiation among populations of a species is frequently observed in the marine environment. We investigated the population genetic structure of the free-living marine nematode Pellioditis marina. A total of 426 bp of the mitochondrial cytochrome oxidase subunit 1 (COI) gene were surveyed on a geographical scale of approximately 100 km during spring 2003. Nematodes were collected from 2 coastal locations in Belgium, and from 2 estuaries and a saltwater lake (Lake Grevelingen) in The Netherlands. Molecular variation was assessed with the single-strand conformation polymorphism (SSCP) method. In total, 32 different haplotypes were observed, and sequence divergence among 452 individuals ranged from 0.2 to 10.6%. We discovered 4 distinct mitochondrial lineages, with low divergences within the lineages (0.2 to 1.6%) and high divergences between the lineages (5.1 to 10.6%). The nuclear ribosomal ITS (internal transcribed spacer) region showed concordant phylogenetic patterns, suggesting that nematode species diversity may be considerably underestimated. Analysis of molecular variance (AMOVA) indicated a strong genetic differentiation among populations. The Lake Grevelingen population was clearly differentiated from all other populations, but genetic structuring was also significant within the Westerschelde and was correlated with gradients in salinity and pollution. The observed population genetic structure is in accordance with the limited active dispersal capacity of P. marina, but is at variance with its significant potential for passive dispersal. We therefore suggest that autecological characteristics, including short generation time, high colonization potential and local adaptation, may be at the basis of this nematode’s population genetic structure