Les profils de composition en oligoéléments des pollens,marqueurs potentiels en cladistique végétale

In botany tentative attempts have been made to classify species, based not on the plant as a whole, but on a particular character, for example pollen characteristics. Pollen, which is involved in the transmission of male genetic information during sexual reproduction, is of particular interest in distinguishing plants and their relationships.

These characters, observed in photon- and scanning electron- microscopy are symmetry, form, number and position of germinating areas. Being genetically stable for a given species, they identify a plant.

Recently, a novel character has been added: the concentration of elements in the exine, determined by electron probe micro-X-ray analysis. It is interesting to follow relationship of plant species, based on the mineral composition of their pollen as a whole, taking into account both plastic and oligoelements, obtained via an inductive coupled plasma spectrometer. Samples of pollen from different plant species, at distinct taxonomic levels, were analyzed; the results were submitted to a normalisation procedure and the standard patterns obtained were investigated by means of a number of numerical techniques (clustering and factor analysis). The aim was to establish if elements could be considered as chemical markers in plant cladistics. The mineral composition in a given species appeared quite stable and this furnished a convenient identification-critorion.

This approach further allows a chemo-taxonomy of species, in as much as organization of families, and perhaps orders, would conform to the phylogenetic proximity-criterion. Hence, we found clusters including pollen of Gramineae, Coniferae, Betulaceae…

This methodology, that should be completed and corroborated on a wider range of samples would provide an original responsee to the problems of identification and classification encountered in a pollen bank. It follows that:

Hence, the working hypothesis that the chemical markers and, in particular, oligo-elements, complete pollen typologies based on morphological and structural characters, appears quite reasonable.

In conclusion, this paper brings a complement to the mineral composition of the exine.

En botanique, des tentatives ont été faites pour classer les espèces non plus à partir d'individus pris dans leur intégralité, mais sur la base d'une de leurs particularités, par exemple à partir des caractéristiques offertes par les pollens. Ainsi, le pollen, dont le rôle est de transmettre l'information génétique mâle de la plante au moment de la reproduction sexuée, présente des caractères de premier ordre utilisables pour distinguer les différentes plantes et pour situer leur parenté et leur filiation.

Ces caractères, que l'on observe en microscopies photonique et électronique à balayage sont la symétrie, la forme, le nombre et la position des zones germinatives. Pour une espèce génétiquement stable, ils constituent la carte d'identité de la plante.

Il est intéressant de continuer à explorer la voie de la structuration des espèces végétales basée sur la connaissance chimique du pollen en déterminant sa composition en oligo-éléments par l'utilisation d'un spectromètre à plasma à couplage inductif. Ainsi, des échantillons de pollens appartenant à diverses espèces végétales situées à différents niveaux taxinomiques ont été analysés et les résultats normalisés sous forme de profils standard ont été soumis à différentes techniques d'analyse statistique mathématique (classification automatique et analyse factorielle). Le but de cette approche est d'apprécier l'aptitude des éléments minéraux à être des marqueurs chimiques en cladistique végétale.

Les résultats obtenus ont permis de constater la relative stabilité du profil en composition minérale au sein d'une même espèce végétale, ce qui donne accès à un critère d'identification commode.

Cette approche permet d'autre part une chimiotaxinomie des plantes étudiées.

Cette approche méthodologique semble susceptible d'apporter une réponse originale aux problèmes de conservation. Les pollens conservés doivent avoir la même composition minérale que les pollens frais.

— the pattern of pollen composition of oligo-elements, calcium and magnesium is a marker in plant cladistics. Since a typology depending on proximity is found between plant species, families and orders.

— an unknown pollen sample may be located, tentatively, on the base of a described model of pollen relation (shortest connexion network — Prim algorithm — and pollen of Bactris-oil palm and Phoenix dactylifera).     

Comparative proteomics analyses reveal a potential biomarker for the detection of vancomycin-intermediate Staphylococcus aureus strains

Vancomycin-intermediate Staphylococcus aureus (VISA) strains tend to develop during glycopeptide treatment of infections caused by methicillin-resistant S. aureus (MRSA). Rapid and effective detection methods for VISA strains are lacking, and mechanisms of resistance are unclear. Here, global comparative proteomic approaches have been used to identify potential biomarkers of intermediate vancomycin resistance. With the use of high-resolution two-dimensional gels and iTRAQ mass tagging, numerous proteins were found to be differentially expressed between clinical MRSA and VISA isolates of the same multilocus sequence type. One of these, the predicted lytic transglycosylase SAV2095 (SceD-like protein), was selected for further study based on both its high level of induction in Mu50 and its predicted role in modeling the cell wall, which is the target of vancomycin. Relative SAV2095 mRNA expression levels were compared between 25 MRSA and VISA/heterogeneous VISA clinical isolates by real-time RT-PCR. The SAV2095 mRNA was significantly induced in all VISA isolates relative to all MRSA strains ( p < 0.001), and significant induction of SAV2095 was also seen for several potential heterogeneous VISA strains that appear vancomycin-sensitive by standard minimum inhibitory concentration-determining methods. Furthermore, strains selected in vitro for increasing levels of resistance from four unrelated clinical MRSA isolates displayed concomitant increases in levels of SAV2095 expression. Together, these results suggest that SAV2095 expression level could serve as a molecular diagnostic marker for the rapid detection of VISA.     

Microbiome dynamics of human epidermis following skin barrier disruption

Background

Recent advances in sequencing technologies have enabled metagenomic analyses of many human body sites. Several studies have catalogued the composition of bacterial communities of the surface of human skin, mostly under static conditions in healthy volunteers. Skin injury will disturb the cutaneous homeostasis of the host tissue and its commensal microbiota, but the dynamics of this process have not been studied before. Here we analyzed the microbiota of the surface layer and the deeper layers of the stratum corneum of normal skin, and we investigated the dynamics of recolonization of skin microbiota following skin barrier disruption by tape stripping as a model of superficial injury.

Results

We observed gender differences in microbiota composition and showed that bacteria are not uniformly distributed in the stratum corneum. Phylogenetic distance analysis was employed to follow microbiota development during recolonization of injured skin. Surprisingly, the developing neo-microbiome at day 14 was more similar to that of the deeper stratum corneum layers than to the initial surface microbiome. In addition, we also observed variation in the host response towards superficial injury as assessed by the induction of antimicrobial protein expression in epidermal keratinocytes.

Conclusions

We suggest that the microbiome of the deeper layers, rather than that of the superficial skin layer, may be regarded as the host indigenous microbiome. Characterization of the skin microbiome under dynamic conditions, and the ensuing response of the microbial community and host tissue, will shed further light on the complex interaction between resident bacteria and epidermis.     

Respect for outsiders? respect for the law? the moral evaluation of high scale issues by US immigration officers

High-scale morality is the study of moral ideas and sentiments deployed in relations that encompass multiple, geographically or socially distant populaces. The envisioning of distant people, their attributed moral personhood, the evaluation of their perceived behaviour, and the rectification of wrongs through the use of powerful organizations are key topics in high-scale morality. High-scale morality differs from existing anthropological approaches that emphasize local ethnography or contrastive moral ideas; it addresses the moralization of issues like world hunger, the drug trade, or international migration. The officers of the US Immigration and Naturalization Service understand and evaluate legal and illegal immigrants, as well as directly enacting moral rectification for the US polity. As they resolve moral dilemmas on their job, they utilize pervasive models for moral thought and action in capitalist, individualist, stratified, and bureaucratized societies. The article finishes by considering directions in which anthropology can contribute to understanding the moral dimension of global issues.     

Protein cofactors and substrate influence Mg2+-dependent structural changes in the catalytic RNA of archaeal RNase P

The ribonucleoprotein (RNP) form of archaeal RNase P comprises one catalytic RNA and five protein cofactors. To catalyze Mg²⁺-dependent cleavage of the 5′ leader from pre-tRNAs, the catalytic (C) and specificity (S) domains of the RNase P RNA (RPR) cooperate to recognize different parts of the pre-tRNA. While ∼250–500 mM Mg²⁺ renders the archaeal RPR active without RNase P proteins (RPPs), addition of all RPPs lowers the Mg²⁺ requirement to ∼10–20 mM and improves the rate and fidelity of cleavage. To understand the Mg²⁺- and RPP-dependent structural changes that increase activity, we used pre-tRNA cleavage and ensemble FRET assays to characterize inter-domain interactions in Pyrococcus furiosus (Pfu) RPR, either alone or with RPPs ± pre-tRNA. Following splint ligation to doubly label the RPR (Cy3-RPR_{C domain} and Cy5-RPR_{S domain}), we used native mass spectrometry to verify the final product. We found that FRET correlates closely with activity, the Pfu RPR and RNase P holoenzyme (RPR + 5 RPPs) traverse different Mg²⁺-dependent paths to converge on similar functional states, and binding of the pre-tRNA by the holoenzyme influences Mg²⁺ cooperativity. Our findings highlight how Mg²⁺ and proteins in multi-subunit RNPs together favor RNA conformations in a dynamic ensemble for functional gains.     

Oral exudate as a mediator of behavior in larval eastern and western spruce budworms (Lepidoptera: Tortricidae)

The production of oral exudate by larval eastern and western spruce budworms,Choristoneura fumiferana (Clem.) andChoristoneura occidentalis Free., respectively, was investigated in the laboratory. All larvae except those entering into a molt exhibited aggressive behavior and produced exudate in response to handling or intraspecific encounters. Larvae could be induced to produce exudate up to four times over 2–3 min and produced an average of 1.92±0.04 µl (X ± SE) per induction. Larvae on foliage spent much of their time maintaining their silken feeding tunnel, including spinning and combing silk and removing frass. Exposure to conspecific oral exudate deposited inside the tunnel, or released by agitated larvae inside the tunnel, increased the proportion of larvae that dispersed away from the tunnels and, apparently, increased the larval sensitivity to disturbances. The behavior induced by the oral exudate indicates that it acts as an epideictic (spacing) pheromone.     

The effect of poly(ADP-ribosyl)ation on native and H1-depleted chromatin. A role of poly(ADP-ribosyl)ation on core nucleosome structure

The effect of poly(ADP-ribosyl)ation on native and H1-depleted chromatin was analyzed by gel electrophoresis, electron microscopy, and velocity sedimentation. In parallel, the interaction of automodified poly(ADP-ribose) polymerase with native and H1-depleted chromatin was analyzed. In H1-depleted chromatin histone H2B becomes the major poly(ADP-ribose) histone acceptor protein, whereas in native chromatin histone H1 was the major histone acceptor. Poly(ADP-ribosyl)ation of H1-depleted chromatin prevented the recondensation of polynucleosomes reconstituted with exogenous histone H1. This is probably due to the presence of modified poly(ADP-ribose) polymerase and hyper(ADP-ribosyl)ated histone H2B. Indeed, about 40% of the modified enzyme remained associated with H1-depleted chromatin, while less than 1% of the modified enzyme was bound to native chromatin. The influence of poly(ADP-ribosyl)ation on the chromatin conformation was also studied at the level of nucleosome in using monoclonal and polyclonal antibodies specific for individual histones and synthetic peptides of histones. In native chromatin incubated in the presence of Mg2+ there was a drop in the accessibility of histone epitopes to monoclonal and polyclonal antibodies whereas upon poly(ADP-ribosyl)ation their accessibility was found to remain even in the presence of Mg2+. In poly(ADP-ribosyl)ated H1-depleted chromatin an increased accessibility of some histone tails to antibodies was observed.