Why do Gull-billed Terns Gelochelidon nilotica feed on fiddler crabs Uca tangeri in Guinea-Bissau?

Gull-billed Terns Gelochelidon nilotica wintering in Guinea Bissau mainly fed on fiddler crabs Uca tangeri and were occasionally seen feeding on fish and locusts. As fiddler crabs have a low energy content, terns need a large gross intake to meet daily energy demands. Fiddler crabs also have a low ratio of digestible flesh to exoskeleton, and therefore tern food intake may be limited by gut capacity. Activity budgets of Gullbilled Terns feeding on fiddler crabs showed that a considerable part of the time was spent resting. The duration of resting intervals increased with energy intake and was positively correlated with the metabolisable energy content of the crab eaten, suggesting that resting periods were required for a proper digestion. The poor quality of fiddler crabs was offset by high capture rates. So daily energy expenditure of the terns could easily be met by feeding on fiddler crabs. Even when resting pauses were included in foraging time, foraging for only 1.5 hours on fiddler crabs satisfied the terns&rsquo; daily energy demands. Instead, feeding on energy-rich fish would require about 2.5 hours to satisfy daily energy demands. Compared to the more specialised piscivorous Little Tern Sternula albifrons and Sandwich Tern Sterna sandvicensis, capture rate of fish was poor in Gull-billed Terns. From an energetic point of view, wintering Gull-billed Terns feeding on fiddler crabs seem to have an easy living in Guinea Bissau.<br /

Forensic Identification of Condom Lubricants by Advanced Statistical Analysis Processing of Direct Analysis in Real Time Mass Spectrometric Data – Towards Development of a Condom Residue Database for Forensic Science Practitioners

The ability to identify condom derived trace evidence is gaining importance because of the increasing frequency with which perpetrators of sexual assault use condoms in order to avoid leaving behind incriminating DNA evidence that might link them to the crime. Although DNA remains the gold standard for sexual assault evidence, other forms of trace evidence are needed in its absence. When condoms are used, the lubricants associated with them are the trace evidence. For the lubricant residue to be useful in a forensics context, a database of chemical signatures of lubricants against which acquired evidence can be screened is required, so that condom brands and types can be identified from the trace evidence. Towards the goal of developing such a database, this study used direct analysis in real time-high resolution mass spectrometry (DART-HRMS) to analyze 110 different types of condoms representing 16 brands. Over 700 spectra were acquired, each serving as a chemical fingerprint for the analyzed condom. The results showed that condoms of the same type within different brands exhibited the same chemical signatures, which differed from condoms of other brands, even when the condoms were advertised to have the same characteristics. For example, the mint flavored condoms of different brands had distinct diagnostic chemical signatures that allowed them to be distinguished from one another, even though they all contained the same chemical components that conferred the mint flavor. Both supervised and unsupervised multivariate statistical analyses were performed on the data. Hierarchical clustering analysis (unsupervised) showed that condoms could be differentiated by brand. Kernel discriminant analysis (supervised) showed that condoms within a given brand could be distinguished. The observed leave-one-out cross validation was 90-100% depending upon the brand. This indicates that a strong database has been developed with the capability of serving as a presumptive test that can be used not only to identify brands, but also the particular condom type within a brand. This database can be readily expanded as additional condom types emerge, and may be particularly useful for corroborating the accounts of victims, or exonerating the falsely accused in cases where DNA evidence is lacking. The positive brand identification of unknown condom residues implies that the database could serve as a tool to assist forensic science practitioners in prosecuting sexual assault cases

Réalisation de structures optiques verticales en verres de chalcogénure pour des applications dans le proche et moyen infrarouge

National audienceDes structures verticales que sont des miroirs de Bragg et des microcavités ont été élaborées en verres de chalcogénure. Une étude préliminaire a permis d'étudier l'indice de réfraction des différentes couches de verres massifs de chalcogénure ainsi que la vitesse de formation de ces couches déposées par PLD. L'objectif de ce travail est de réaliser des microcavités actives en dopant la couche séparatrice par des ions Erbium émettant à 1,53 et à 4,65 µm

Global Origin of Mycobacterium tuberculosis in the Midlands, UK

DNA fingerprinting data for 4,207 Mycobacterium tuberculosis isolates were combined with data from a computer program (Origins). Largest population groups were from England (n = 1,031) and India (n = 912), and most prevalent strains were the Euro-American (45%) and East African–Indian (34%) lineages. Combining geographic and molecular data can enhance cluster investigation

Manipulation and Optical Detection of Colloidal Functional Plasmonic Nanostructures in Microfluidic Systems

The very strong optical resonances of plasmonic nanostructures can be harnessed for sensitive detection of chemical and biomolecular analytes in small volumes. Here we describe an approach towards optical biosensing in microfluidic systems using plasmonic structures (functionalized gold nanoparticles) in colloidal suspension. The plasmonic nanoparticles provide the optical signal, in the form of resonant light scattering or absorption, and the microfluidic environment provides means for selectively manipulating the nanoparticles through fluid dynamics and electric fields. In the first part we discuss recent literature on functionalized colloidal particles and the methods for handling them in microfluidic systems. Then we experimentally address aspects of nanoparticle functionalization, detection through plasmonic resonant light scattering under dark-field illumination and the electrokinetic behavior of the particles under the action of an alternating electric field

A Virtual Testing Approach for Laminated Composites Based on Micromechanics

International audienceThe chapter deals with a crucial question for the design of composite structures: how can one predict the evolution of damage up to and including final fracture? Virtual testing, whose goal is to drastically reduce the huge number of industrial tests involved in current characterization procedures, constitutes one of today’s main industrial challenges. In this work, one revisits our multiscale modeling answer through its practical aspects. Some complements regarding identification, kinking, and crack initiation are also given. Finally, the current capabilities and limits of this approach are discussed, as well as the computational challenges that are inherent to “Virtual Structural Testing.

Genetic diversity of Mycobacterium tuberculosis isolated from tuberculosis patients in the Serengeti ecosystem in Tanzania

SummaryThis study was part of a larger cross-sectional survey that was evaluating tuberculosis (TB) infection in humans, livestock and wildlife in the Serengeti ecosystem in Tanzania. The study aimed at evaluating the genetic diversity of Mycobacterium tuberculosis isolates from TB patients attending health facilities in the Serengeti ecosystem. DNA was extracted from 214 sputum cultures obtained from consecutively enrolled newly diagnosed untreated TB patients aged ≥18 years. Spacer oligonucleotide typing (spoligotyping) and Mycobacterium Interspersed Repetitive Units and Variable Number Tandem Repeat (MIRU-VNTR) were used to genotype M. tuberculosis to establish the circulating lineages. Of the214 M. tuberculosis isolates genotyped, 55 (25.7%) belonged to the Central Asian (CAS) family, 52 (24.3%) were T family (an ill-defined family), 38 (17.8%) belonged to the Latin American Mediterranean (LAM) family, 25 (11.7%) to the East-African Indian (EAI) family, 25 (11.7%) comprised of different unassigned (‘Serengeti’) strain families, while 8 (3.7%) belonged to the Beijing family. A minority group that included Haarlem, X, U and S altogether accounted for 11 (5.2%) of all genotypes. MIRU-VNTR typing produced diverse patterns within and between families indicative of unlinked transmission chains. We conclude that, in the Serengeti ecosystem only a few successful families predominate namely CAS, T, LAM and EAI families. Other types found in lower prevalence are Beijing, Haarlem, X, S and MANU. The Haarlem, EAI_Somalia, LAM3 and S/convergent and X2 subfamilies found in this study were not reported in previous studies in Tanzania

The Forest behind the Tree: Phylogenetic Exploration of a Dominant Mycobacterium tuberculosis Strain Lineage from a High Tuberculosis Burden Country

BACKGROUND: Genotyping of Mycobacterium tuberculosis isolates is a powerful tool for epidemiological control of tuberculosis (TB) and phylogenetic exploration of the pathogen. Standardized PCR-based typing, based on 15 to 24 mycobacterial interspersed repetitive unit-variable number of tandem repeat (MIRU-VNTR) loci combined with spoligotyping, has been shown to have adequate resolution power for tracing TB transmission and to be useful for predicting diverse strain lineages in European settings. Its informative value needs to be tested in high TB-burden countries, where the use of genotyping is often complicated by dominance of geographically specific, genetically homogeneous strain lineages. METHODOLOGY/PRINCIPAL FINDINGS: We tested this genotyping system for molecular epidemiological analysis of 369 M. tuberculosis isolates from 3 regions of Brazil, a high TB-burden country. Deligotyping, targeting 43 large sequence polymorphisms (LSPs), and the MIRU-VNTRplus identification database were used to assess phylogenetic predictions. High congruence between the different typing results consistently revealed the countrywide supremacy of the Latin-American-Mediterranean (LAM) lineage, comprised of three main branches. In addition to an already known RDRio branch, at least one other branch characterized by a phylogenetically informative LAM3 spoligo-signature seems to be globally distributed beyond Brazil. Nevertheless, by distinguishing 321 genotypes in this strain population, combined MIRU-VNTR typing and spoligotyping demonstrated the presence of multiple distinct clones. The use of 15 to 24 loci discriminated 21 to 25% more strains within the LAM lineage, compared to a restricted lineage-specific locus set suggested to be used after SNP analysis. Noteworthy, 23 of the 28 molecular clusters identified were exclusively composed of patient isolates from a same region, consistent with expected patterns of mostly local TB transmission. CONCLUSIONS/SIGNIFICANCE: Standard MIRU-VNTR typing combined with spoligotyping can reveal epidemiologically meaningful clonal diversity behind a dominant M. tuberculosis strain lineage in a high TB-burden country and is useful to explore international phylogenetical ramifications

Proposal of a consensus set of hypervariable mycobacterial interspersed repetitive-unit-variable-number tandem-repeat loci for subtyping of mycobacterium tuberculosis Beijing isolates

Mycobacterium tuberculosis Beijing strains represent targets of special importance for molecular surveillance of tuberculosis (TB), especially because they are associated with spread of multidrug resistance in some world regions. Standard 24-locus mycobacterial interspersed repetitive-unit–variable-number tandem-repeat (MIRU-VNTR) typing lacks resolution power for accurately discriminating closely related clones that often compose Beijing strain populations. Therefore, we evaluated a set of 7 additional, hypervariable MIRU-VNTR loci for better resolution and tracing of such strains, using a collection of 535 Beijing isolates from six world regions where these strains are known to be prevalent. The typeability and interlaboratory reproducibility of these hypervariable loci were lower than those of the 24 standard loci. Three loci (2163a, 3155, and 3336) were excluded because of their redundant variability and/or more frequent noninterpretable results compared to the 4 other markers. The use of the remaining 4-locus set (1982, 3232, 3820, and 4120) increased the number of types by 52% (from 223 to 340) and reduced the clustering rate from 58.3 to 36.6%, when combined with the use of the standard 24-locus set. Known major clonal complexes/24-locus-based clusters were all subdivided, although the degree of subdivision varied depending on the complex. Only five single-locus variations were detected among the hypervariable loci of an additional panel of 92 isolates, representing 15 years of clonal spread of a single Beijing strain in a geographically restricted setting. On this calibrated basis, we propose this 4-locus set as a consensus for subtyping Beijing clonal complexes and clusters, after standard typing