Étude de la résistance aux antibiotiques des entérocoques d'origine animale du Québec

Les entérocoques font partie de la flore normale intestinale des animaux et des humains. Plusieurs études ont démontré que les entérocoques d’origine animale pouvaient représenter un réservoir de gènes de résistance aux antibiotiques pour la communauté humaine et animale. Les espèces Enterococcus faecalis et Enterococcus faecium sont importantes en santé publique; elles sont responsables d’environ 12% de toutes les infections nosocomiales aux États-Unis. Au Canada, les cas de colonisation et/ou d’infections à entérocoques résistants à la vancomycine ont plus que triplé de 2005 à 2009. Un total de 387 isolats E. faecalis et E. faecium aviaires, et 124 isolats E. faecalis porcins ont été identifiés et analysés pour leur susceptibilité aux antibiotiques. De hauts pourcentages de résistance envers les macrolides et les tétracyclines ont été observés tant chez les isolats aviaires que porcins. Deux profils phénotypiques prédominants ont été déterminés et analysés par PCR et séquençage pour la présence de gènes de résistance aux antibiotiques. Différentes combinaisons de gènes de résistance ont été identifiées dont erm(B) et tet(M) étant les plus prévalents. Des extractions plasmidiques et des analyses par hybridation ont permis de déterminer, pour la première fois, la colocalisation des gènes erm(B) et tet(M) sur un plasmide d’environ 9 kb chez des isolats E. faecalis porcins, et des gènes erm(B) et tet(O) sur un plasmide de faible poids moléculaire d’environ 11 kb chez des isolats E. faecalis aviaires. De plus, nous avons démontré, grâce à des essais conjugatifs, que ces plasmides pouvaient être transférés. Les résultats ont révélé que les entérocoques intestinaux aviaires et porcins, lesquels peuvent contaminer la viande à l’abattoir, pouvaient représenter un réservoir de gènes de résistance envers la quinupristine-dalfopristine, la bacitracine, la tétracycline et les macrolides. Afin d’évaluer l’utilisation d’un antisérum polyclonal SA dans l’interférence de la résistance à de fortes concentrations de bacitracine (gènes bcrRAB), lors d’un transfert conjugatif répondant aux phéromones, un isolat multirésistant E. faecalis aviaire a été sélectionné. Après induction avec des phéromones produites par la souche réceptrice E. faecalis JH2-2, l’agrégation de la souche donatrice E. faecalis 543 a été observée ainsi que des fréquences de transfert élevées en bouillon lors d’une courte période de conjugaison. Le transfert conjugatif des gènes asa1, traB et bcrRAB ainsi que leur colocalisation a été démontré chez le donneur et un transconjugant T543-1 sur un plasmide de 115 kb par électrophorèse à champs pulsé (PFGE) et hybridation. Une CMI de > 2 048 µg/ml envers la bacitracine a été obtenue tant chez le donneur que le transconjuguant tandis que la souche réceptrice JH2-2 démontrait une CMI de 32 µg/ml. Le séquençage des gènes asa1, codant pour la substance agrégative, et traB, une protéine régulant négativement la réponse aux phéromones, a révélé une association de cet élément génétique avec le plasmide pJM01. De plus, cette étude présente qu’un antisérum polyclonal SA peut interférer significativement dans le transfert horizontal d’un plasmide répondant aux phéromones codant pour de la résistance à de fortes doses de bacitracine d’une souche E. faecalis aviaire multirésistante. Des isolats cliniques E. faecium d’origine humaine et canine ont été analysés et comparés. Cette étude rapporte, pour la première fois, la caractérisation d’isolats cliniques E. faecium résistants à l’ampicilline (EFRA) d’origine canine associés à CC17 (ST17) au Canada. Ces isolats étaient résistants à la ciprofloxacine et à la lincomycine. Leur résistance envers la ciprofloxacine a été confirmée par la présence de substitutions dans la séquence en acides aminés des gènes de l’ADN gyrase (gyrA/gyrB) et de la topoisomérase IV (parC/parE). Des résistances élevées envers la gentamicine, la kanamycine et la streptomycine, et de la résistance envers les macrolides et les lincosamides a également été observées. La fréquence de résistance envers la tétracycline était élevée tandis que celle envers la vancomycine n’a pas été détectée. De plus, aucune résistance n’a été observée envers le linézolide et la quinupristine-dalfopristine. Les données ont démontré une absence complète des gènes esp (protéine de surface des entérocoques) et hyl (hyaluronidase) chez les isolats canins EFRA testés tandis qu’ils possédaient tous le gène acm (adhésine de liaison au collagène d’E. faecium). Aucune activité reliée à la formation de biofilm ou la présence d’éléments CRISPR (loci de courtes répétitions palindromiques à interespaces réguliers) n’a été identifiée chez les isolats canins EFRA. Les familles de plasmide rep6 and rep11 ont significativement été associées aux isolats d’origine canine. Les profils PFGE des isolats d’origine humaine et canine n'ont révélé aucune relation (≤ 80%). Ces résultats illustrent l'importance d'une utilisation judicieuse des antibiotiques en médecine vétérinaire afin d’éviter la dissémination zoonotique des isolats EFRA canins. Nous pensons que ces résultats contribueront à une meilleure compréhension des mécanismes de résistance aux antibiotiques et de leurs éléments mobiles ainsi qu’à de nouvelles stratégies afin de réduire le transfert horizontal de la résistance aux antibiotiques et des facteurs de virulence.

A orientação homossexual e as investigações acerca da existência de componentes biológicos e genéticos determinantes; The homosexual orientation and investigations about the existence of components biological and genetics determinants

The male and female homosexual orientation has substantial prevalence in humans and can be explained by determinants of various levels: biological, genetic, psychological, social and cultural. However, the biological and genetic evidence have been the main hypotheses tested in scientific research in the world. This article aims to review research studies about the existence of genetic and biological evidence that determine homosexual orientation. Was conducted a review of the literature, using the database MedLine/PubMed and Google scholar. The papers and books were searched in Portuguese and English, using the following keywords: sexual orientation, sexual behavior, homosexuality, developmental Biology and genetics. Was selected papers of the last 22 years. Were found five main theories about the biological components: (1) fraternal birth order, (2) brain androgenization and 2D:4D ratio; (3) brain activation by pheromones; and (4) epigenetic inheritance; and four theories about the genetic components: (1) genetic polymorphism; (2) pattern of X-linked inheritance; (3) monozygotic twins; and (4) sexual antagonistic selection. Concluded that there were many scientific evidence found over time to explain some of biological and genetic components of homosexuality, especially in males. However, today, there is no definitive explanation about what are the determinants of homosexual orientation components.

Floral volatiles controlling ant behaviour

P>1. Ants show complex interactions with plants, both facultative and mutualistic, ranging from grazers through seed predators and dispersers to herders of some herbivores and guards against others. But ants are rarely pollinators, and their visits to flowers may be detrimental to plant fitness. 2. Plants therefore have various strategies to control ant distributions, and restrict them to foliage rather than flowers. These 'filters' may involve physical barriers on or around flowers, or 'decoys and bribes' sited on the foliage (usually extrafloral nectaries - EFNs). Alternatively, volatile organic compounds (VOCs) are used as signals to control ant behaviour, attracting ants to leaves and/or deterring them from functional flowers. Some of the past evidence that flowers repel ants by VOCs has been equivocal and we describe the shortcomings of some experimental approaches, which involve behavioural tests in artificial conditions. 3. We review our previous study of myrmecophytic acacias, which used in situ experiments to show that volatiles derived from pollen can specifically and transiently deter ants during dehiscence, the effects being stronger in ant-guarded species and more effective on resident ants, both in African and Neotropical species. In these plants, repellence involves at least some volatiles that are known components of ant alarm pheromones, but are not repellent to beneficial bee visitors. 4. We also present new evidence of ant repellence by VOCs in temperate flowers, which is usually pollen-based and active on common European ants. We use these data to indicate that across a wide range of plants there is an apparent trade-off in ant-controlling filter strategies between the use of defensive floral volatiles and the alternatives of decoying EFNs or physical barriers.

Sexually Dimorphic Tegumental Gland Openings in Laniatores (Arachnida, Opiliones), With New Data on 23 Species

Sexually dimorphic glands often release sexual pheromones both in vertebrates and invertebrates. Species of Laniatores (Arachnida, Opiliones) seem to depend on chemical communication but few studies have addressed this topic. In this study, we review the literature for the Phalangida and present new data for 23 species of Laniatores. In 16 taxa, we found previously undescribed sexually dimorphic glandular openings on the femur, patella, metatarsus, and tarsus of legs I and metatarsus of legs III and IV For the other species, we provide scanning electron micrographs of previously undescribed sexually dimorphic setae and pegs located on swollen regions of the legs. We also list additional species in which males have swollen regions on the legs, including the tibia, metatarsus, and tarsus of legs I, trochanter and tibia of legs II, femur, metatarsus, and tarsus of legs III, and metatarsus and tarsus of legs IV. The function and biological role of the secretions released by these glands are discussed. J. Morphol. 271:641-653, 2010. (C) 2009 Wiley-Liss, Inc.

Tellurium in organic synthesis: the enantioselective synthesis of the pheromone blend components of Mayetiola destructor, Drosophila mulleri and Contarinia pisi

The components of the pheromone blend of Mayetiola destructor, Drosophila mulleri, and Contarinia pisi were synthesized in high enantiomeric excess (99% ee) from a common enantiopure dianion prepared from an enantiopure hydroxytelluride. (C) 2009 Elsevier Ltd. All rights reserved.

Lipid composition of cashmere goat fibres

This study examined the differences in the chemical composition, particularly fatty acids, of the lipid extracted from the fibre of bucks, does and castrated goats. The study provides a more detailed understanding of the chemical composition of buck fibre lipid and how it varies throughout the year, and also details the effect of body region and nutrition on the production and chemical composition of lipid from buck fibre. Lipid was extracted with either petroleum ether (non-polar) or chloroform/methanol azeotrope (polar) and analysed by gas chromatography and gas chromatography-mass spectrometry. The more polar solvent system extracted larger amounts of lipid and more of each individual fatty acid. The following buck specific ethyl branched fatty acids were identified: 2-ethylhexanoic, 4-ethylhexanoic, 2-ethyloctanoic, 4-ethyloctanoic, 6-ethyloctanoic, 2-ethyldecanoic, 4-ethyldecanoic, 2-ethyldodecanoic, 6-ethyldodecanoic, 4-ethyldodecanoic, 2-ethyltetradecanoic, 6-ethyltetradecanoic, 4-ethyltetradecanoic, 2-ethylhexadecanoic and 4-ethyloctadecanoic acids. Of these buck specific fatty acids only 4-ethylhexanoic (T), 4-ethyloctanoic, 4-ethyldecanoic, 4-ethyldodecanoic, 6-ethyldodecanoic (T), 4-ethyltetradecanoic, 2-ethylhexadecanoic (T) and 4-ethylhexadecanoic acids have been previously identified or tentatively identified (T) in buck fibre extracts. This shows that the chemical composition of buck fibre lipid is more complex than previously reported, and that it may be more difficult than previously thought to artificially duplicate the odour of the buck. Buck fibre samples had lower average concentrations of 2-methylpropanoic, 2-methylbutanoic, iso-pentadecanoic, anteiso-pentadecanoic, iso-hexadecanoic, anteiso-heptadecanoic, iso-octadecanoic and anteiso-nonadecanoic acids as compared with fibre samples from does, spayed does, or wethers that were castrated at one month of age. The reduced concentrations of these fatty acids in buck fibre extracts were likely to be due to the synthesis of ethyl branched derivatives of iso and anteiso fatty acids. Buck fibre samples had higher concentrations of benzoic acid as compared with fibre samples from does, spayed does, or wethers that were castrated at one month of age. The significance of these results is that non buck specific fatty acids may also make a contribution to the odour of bucks. When fibre samples were collected at various times throughout the year, it was found that the bucks had increased amounts of lipid and ethyl branched fatty acids in fibre samples shorn from March to September, as compared with fibre samples shorn in November and January. The increase in the amount of lipid and ethyl branched fatty acids corresponded with both the rutting period of the buck and the period when the buck odour was increased. This suggests that ethyl branched fatty acids could be pheromones. The variation in lipid content and fatty acid composition was also examined between fibre samples collected from different body regions of the buck during April, as alterations in sebaceous gland activity around the neck during rutting have been reported. It was found that the average amount of lipid in the neck region of the bucks was not statistically higher than the average amounts in the midside and hind regions. However, the ethyl branched fatty acid concentrations were statistically higher in the fibre from around the neck as compared with the fibre from the other body regions, which is consistent with the odour of the buck being most pronounced around the head and neck region. The lipid content and composition of fibre samples from bucks fed high and low quality diets (lucerne and pangola grass, respectively) was examined to determine the effect of nutrition on buck specific components. The high quality diet increased the amount of lipid and ethyl branched fatty acids in fibre samples collected in April from the neck, midside and hind regions, as compared with fibre samples from the corresponding body regions from bucks fed the low quality diet. Thus it may be possible for the pheromone levels of bucks to be increased by simply providing them with good nutrition. The lipid content and ethyl branched fatty acid concentrations of fibre samples increased earlier in the year for the lucerne fed bucks as compared with the pangola grass fed bucks. The lucerne fed bucks had increased concentrations of ethyl branched fatty acids in fibre samples shorn during December to June (6 months) whereas the pangola grass fed bucks had increased concentrations of ethyl branched fatty acids in fibre samples shorn during April to August (4 months). These observations show that good nutrition can result in both the earlier production of ethyl branched fatty acids and an extended period when ethyl branched fatty acids are produced. This suggests that nutrition can be used to manipulate pheromone levels in the buck. The period when the ethyl branched fatty acids were increased corresponded with the period when the plasma luteinizing hormone (LH) and testosterone concentrations, odour and sebaceous gland volume of the bucks were increased, which supports the assumption that ethyl branched fatty acids are involved in odour production and act as pheromones.

Semiochemicals in merino ewes : field effects and chemical identification

[No Abstract]

Identification of an attractin-like pheromone in the mucus-secreting hypobranchial gland of the abalone Haliotis asinina linnaeus.

Pheromones are chemicals used to communicate between animals of the same species, and are thought to be used by most marine animals. With limited vision, abalone primarily sense their world chemically, and pheromones may play an important role in settlement, attraction, recognition, alarm, and reproduction. Despite this, there has been no detailed investigation into pheromone substances, both in their precise biochemical nature or pheromonal function. In this study, we investigated the presence of pheromonelike substances from the hypobranchial gland of the abalone Haliotis asinina using bioassays, immunohistochemistry, Western blotting, and reverse-phase high-performance liquid chromatography (RP-HPLC). The hypobranchial gland of many prosobranchial marine molluscs has been classified as a sex auxiliary gland releasing unknown substances during spawning. In our study, cephalic tentacle assays demonstrated that the cell extracts of the hypobranchial gland contain chemical cues that are sensed by conspecifics. An antibody against the sea slug “attractin” pheromone was used as a probe to localize a similar protein in the mucin-secreting cells of the epithelial lining the hypobranchial gland of both male and female abalone. The approximate molecular weight of this abalone attractin-like protein is 30 kDa in both males and females. Fractionation of hypobranchial gland extracts by C5 RP-HPLC could not selectively purify this protein, and no sex-specific differences were observed. We predict that the attractin-like protein could be one of a number of important proteins involved in maturation, aggregation, and/or spawning behavior of abalone. In future research, additional hypobranchial gland components will be tested further for these types of behavior.

Effects of humidity on the response of the bark beetle Ips grandicollis (Eichhoff) (Coleoptera: Curculionidae: Scolytinae) to synthetic aggregation pheromone

Environmental factors may affect chemical communication between individuals by limiting their ability to detect and respond to these signals. One such factor, high humidity, has been shown to interfere with the normal response of some invertebrate species to their attractant pheromones. The effect of humidity on the response of the five-spined bark beetle, Ips grandicollis, to a synthetic form of the aggregation pheromone component ipsenol, was tested in an experimental chamber in the laboratory. The response was measured as both the number of beetles to reach the pheromone source and the time taken, and was tested under high (>80% relative humidity) and low (30–40% relative humidity) conditions of humidity. There was no significant difference in response of beetles between the two treatments although there was a reduction in response in the high-humidity treatment when relative humidity levels were in excess of 90%. These findings suggest that atmospheric humidity does not influence bark beetles response to synthetic pheromone, except perhaps in unlikely conditions of excessive humidity.

The mode of pheromone evolution: evidence from bark beetles

Sex and aggregation pheromones consist of species-specific blends of chemicals. The way in which different species’ blends have evolved has been the subject of some debate. Theoretical predictions suggest that differences between species have arisen not through the accruing of small changes, but through major shifts in chemical composition. Using data on the aggregation pheromones of 34 species of bark beetle from two genera, Dendroctonus and Ips, we investigated how the distributions of the chemical components of their pheromone blends mirror their phylogenetic relationships. We tested whether there were consistent patterns that could be used to help elucidate the mode of pheromone evolution. Although there were obvious differences in pheromone blends between the two genera, the differences between species within each genus followed a less clear phylogenetic pattern. In both genera, closely related species are just as different as more distantly related species. Within Dendroctonus, particularly, most chemical components were distributed randomly across the phylogeny. Indeed, for some chemicals, closely related species may actually be more different than would be expected from a random distribution of chemical components. This argues strongly against the idea of minor shifts in pheromone evolution. Instead, we suggest that, within certain phylogenetic constraints, pheromone evolution in bark beetles is characterized by large saltational shifts, resulting in sibling species being substantially phenotypically (i.e. pheromonally) different from one another, thus agreeing with theoretical predictions.

The evolution of pheromone diversity

Pheromones are chemical signals whose composition varies enormously between species. Despite pheromones being a nearly ubiquitous form of communication, particularly among insects, our understanding of how this diversity has arisen, and the processes driving the evolution of pheromones, is less developed than that for visual and auditory signals. Studies of phylogeny, genetics and ecological processes are providing new insights into the patterns, mechanisms and drivers of pheromone evolution, and there is a wealth of information now available for analysis. Future research could profitably use these data by employing phylogenetic comparative techniques to identify ecological correlates of pheromone composition. Genetic analyses are also needed to gain a clearer picture of how changes in receivers are associated with changes in the signal.

The relationship between emergence of the shortest path and information value using ant-like agents

Ant-like agents forage between two points. These agents' probabilistic movements are based on the use of two pheromones; one marking trails towards the goal and another marking trails back to the starting point. Path selection decisions are influenced by the relative levels of attractive and repulsive pheromone in each agent's local environment. Our work in [5] evaluates three pheromone perception strategies, investigating path formation speed, quality, directionality, robustness and adaptability under different parameter settings(degree of randomness, pheromone evaporation rate and pheromone diffusion rate). We re-evaluate two of these strategies in terms of the amount of information they provide using Shannon's formulation [3, 4, 8, 9, 12, 14, 15, 16, 17]. We determine information as the difference between uncertainty before and after path selection decisions. Our focus in this paper is on investigating relationships between the emergence of the shortest path and the amount of stigmergic information that exists in the form of pheromone. Agents are deployed centrally and emergence measures are determined using the worst, reference and best cases observed in [5]. Additionally, the amount of local and global information that is available to agents in each movement step is evaluated. Furthermore, Pearson's correlation coefficients between measures of emergence and the amount of information are calculated. The significance of these correlation coefficients is tested using a 2 tailed test at 1% level of significance. Consequently the relationship between the amount of information and emergent behaviour is established. Significant relationships between information and the emergence of the shortest path exist when strong emergent behaviour is present.

Pheromone production, male abundance, body size, and the evolution of elaborate antennae in moths

The males of some species of moths possess elaborate feathery antennae. It is widely assumed that these striking morphological features have evolved through selection for males with greater sensitivity to the female sex pheromone, which is typically released in minute quantities. Accordingly, females of species in which males have elaborate (i.e., pectinate, bipectinate, or quadripectinate) antennae should produce the smallest quantities of pheromone. Alternatively, antennal morphology may be associated with the chemical properties of the pheromone components, with elaborate antennae being associated with pheromones that diffuse more quickly (i.e., have lower molecular weights). Finally, antennal morphology may reflect population structure, with low population abundance selecting for higher sensitivity and hence more elaborate antennae. We conducted a phylogenetic comparative analysis to test these explanations using pheromone chemical data and trapping data for 152 moth species. Elaborate antennae are associated with larger body size (longer forewing length), which suggests a biological cost that smaller moth species cannot bear. Body size is also positively correlated with pheromone titre and negatively correlated with population abundance (estimated by male abundance). Removing the effects of body size revealed no association between the shape of antennae and either pheromone titre, male abundance, or mean molecular weight of the pheromone components. However, among species with elaborate antennae, longer antennae were typically associated with lower male abundances and pheromone compounds with lower molecular weight, suggesting that male distribution and a more rapidly diffusing female sex pheromone may influence the size but not the general shape of male antennae.

An ant colony system based on the physarum network

The Physarum Network model exhibits the feature of important pipelines being reserved with the evolution of network during the process of solving a maze problem. Drawing on this feature, an Ant Colony System (ACS), denoted as PNACS, is proposed based on the Physarum Network (PN). When updating pheromone matrix, we should update both pheromone trails released by ants and the pheromones flowing in a network. This hybrid algorithm can overcome the low convergence rate and local optimal solution of ACS when solving the Traveling Salesman Problem (TSP). Some experiments in synthetic and benchmark networks show that the efficiency of PNACS is higher than that of ACS. More important, PNACS has strong robustness that is very useful for solving a higher dimension TSP.

A multi-objective ant colony optimization algorithm based on the physarum-inspired mathematical model

Multi-objective traveling salesman problem (MOTSP) is an important field in operations research, which has wide applications in the real world. Multi-objective ant colony optimization (MOACO) as one of the most effective algorithms has gained popularity for solving a MOTSP. However, there exists the problem of premature convergence in most of MOACO algorithms. With this observation in mind, an improved multiobjective network ant colony optimization, denoted as PMMONACO, is proposed, which employs the unique feature of critical tubes reserved in the network evolution process of the Physarum-inspired mathematical model (PMM). By considering both pheromones deposited by ants and flowing in the Physarum network, PM-MONACO uses an optimized pheromone matrix updating strategy. Experimental results in benchmark networks show that PM-MONACO can achieve a better compromise solution than the original MOACO algorithm for solving MOTSPs.