Is there a health hazard for building occupants of airborne mineral fibers exposure?

Summary Asbestos containing material (ACM) inside buildings is an important concern for the health of their occupants. In France, for the assessment of airborne asbestos concentrations inside building, we use the indirect TEM measurement method constantly improved from 1978 on. By contrast, in the U.S.A. and UK the direct method is used. We have carried out a study in order to compare mass and numerical concentration fibres from the same samples, the tendency being now to express the results in fibre/litre. Concerning asbestos fibres released from man made mineral fibres (MMMF), optical microscope is used and results are expressed in numerical concentrations. Epidemiological studies of different occupational cohorts suggest that amphibole fibres present a greater health risk than chrysotile. Concerning indoor pollution by mineral wool, the health hazard seems negligible. The appraisal of this public health problem remains to be done. In France, a multidisciplinary study group has been created to provide advices related to corrective actions. Information on this public health problem is expected from the epidemiologic longitudinal survey, still in progress, of a cohort of workers, exposed to ACM in Paris university buildings.     

Factors influencing conception rates of Arab mares in Tunisia

In order to investigate the factors affecting the reproduction efficiency of Arab breeding mares in Tunisia, breeding data corresponding to 2340 mated cycles, over 5 years (from 2000 to 2004), from 555 mares offspring of 50 sires and bred with 17 stallions were analysed using a multivariate logistic regression. We chose logit link function and binomial distribution and we used log-likelihood-ratio (LL) and Wald tests (X² Wald) to test the mean values. The factors of variation included in the model were the year, the stallion, the age of the mare at mating, the sire and the category of the mare. Logistic regression results showed that age and sire affected both the overall conception rate and the first-cycle conception rate of the mares whilst category and stallion influenced only the overall conception rate. To our knowledge, this is the first study showing that the sire of the mare can affect both the first-cycle conception rate and the overall conception rate of the mares.     

Selection of social traits in juvenile Japanese quail affects adults’ behaviour

The inability of animals to cope with their social environment in husbandry systems could be a major source of problems for both animal welfare management and economy. In this context, previous studies selected lines of domestic Japanese quail diverging for their level of social reinstatement, hypothesizing that quail with high levels of social motivation would adapt better to crowded social situations than quail with low levels of social motivation. However, these selections were based only on social motivation evaluated in young birds. As behavioural traits can vary with age, this study analysed the persistence of selected social traits into adulthood. With this in mind, we used several behavioural tests to estimate social motivation of adult females from selected lines for high social reinstatement (HSR, n = 24) and for low social reinstatement (LSR, n = 24). The tests were: open-field tests, emergence tests, separation tests, runway tests and confrontation tests. As birds’ behaviour in these tests can be influenced by the emotive characteristics of the subjects, we measured the emotional reactivity of quail not only during these tests but also in specific emotive tests: tonic immobility tests. Our results showed that the social motivation characteristics of birds persist in adulthood. Adult HSR females still presented a higher social motivation than adult LRS females: their response to social isolation was stronger and their motivation to reach conspecifics and to stay close to them was higher. However, the behavioural expression of social motivation appeared to be modified during development. Whereas vocal behaviour reflected the social motivation of chicks, in isolated contexts, this characteristic was not observed in adult quail.     

Maternal Epigenetic Transmission of Social Motivation in Birds

Behavioural development is a complex phenomenon involving interactions between genetic constraints and environmental influences. One of the most potent environmental influences during the ontogeny of the behavioural characteristics of young is played by mothers. In particular, mammalian mothers modulate the social competences of their young, influencing all their future social life. Here, we investigated the influence of the social characteristics of adoptive mother birds ( Coturnix coturnix japonica ) on the social motivation (origin of every social relationship) of the young they reared. We characterized the social behaviour of standard stock chicks reared by female quail, genetically selected either for low (LSR) or high (HSR) levels of social reinstatement (index of treadmill behaviour which combined the tendency to run towards conspecifics with the tendency to move away from them), to investigate epigenetic transmission of social motivation. Our results show that HSR and LSR adoptive mothers partially transmitted their social characteristics to their young: chicks reared by HSR females presented higher levels of social motivation than chicks reared by LSR females. This maternal influence appeared much clearer in young males than in young females. Our study reveals that, as in mammals, bird mothers influence epigenetically the development of the social behaviour of their young.     

Pak1 and PIX regulate contact inhibition during epithelial wound healing

Wound healing in epithelia requires coordinated cell migration and proliferation regulated by signaling mechanisms that are poorly understood. Here we show that epithelial cells expressing constitutively active or kinase-dead mutants of the Rac/Cdc42 effector Pak1 fail to undergo growth arrest upon wound closure. Strikingly, this phenotype is only observed when the Pak1 kinase mutants are expressed in cells possessing a free lateral surface, i.e. one that is not engaged in contact with neighboring cells. The Pak1 kinase mutants perturb contact inhibition by a mechanism that depends on the Pak-interacting Rac-GEF PIX. In control cells, endogenous activated Pak and PIX translocate from focal complexes to cell-cell contacts during wound closure. This process is abrogated in cells expressing Pak1 kinase mutants. In contrast, Pak1 mutants rendered defective in PIX binding do not impede translocation of activated Pak and PIX, and exhibit normal wound healing. Thus, recruitment of activated Pak and PIX to cell-cell contacts is pivotal to transduction of growth-inhibitory signals from neighboring cells in epithelial wound healing.     

Immobilization of native membrane-bound rhodopsin on biosensor surfaces

In this paper, we evaluated the grafting of G-protein-coupled receptors (GPCRs) onto functionalized surfaces, which is a primary requirement to elaborate receptor-based biosensors, or to develop novel GPCR assays. Bovine rhodopsin, a prototypical GPCR, was used in the form of receptor-enriched membrane fraction. Quantitative immobilization of the membrane-bound rhodopsin either non-specifically on a carboxylated dextran surface grafted with long alkyl groups, or specifically on a surface coated with anti-rhodopsin antibody was demonstrated by surface plasmon resonance. In addition, a new substrate based on mixed self-assembled multilayer that anchors specific anti-receptor antibodies was developed. Electrochemical impedance spectroscopy performed upon deposition of membrane-bound rhodopsin of increasing concentration exhibited a significant change, until a saturation level was reached, indicating optimum receptor immobilization on the substrate. The structures obtained with this new immobilization procedure of the rhodopsin in its native membrane environment are stable, with a controlled density of specific anchoring sites. Therefore, such receptor immobilization method is attractive for a range of applications, especially in the field of GPCR biosensors.     

Age affects the expression of maternal care and subsequent behavioural development of offspring in a precocial bird

Variations of breeding success with age have been studied largely in iteroparous species and particularly in birds: survival of offspring increases with parental age until senescence. Nevertheless, these results are from observations of free-living individuals and therefore, it remains impossible to determine whether these variations result from parental investment or efficiency or both, and whether these variations occur during the prenatal or the postnatal stage or during both. Our study aimed first, to determine whether age had an impact on the expression of maternal breeding care by comparing inexperienced female birds of two different ages, and second, to define how these potential differences impact chicks' growth and behavioural development. We made 22 2-month-old and 22 8-month-old female Japanese quail foster 1-day-old chicks. We observed their maternal behaviour until the chicks were 11 days old and then tested these chicks after separation from their mothers. Several behavioural tests estimated their fearfulness and their sociality. We observed first that a longer induction was required for young females to express maternal behaviour. Subsequently as many young females as elder females expressed maternal behaviour, but young females warmed chicks less, expressed less covering postures and rejected their chicks more. Chicks brooded by elder females presented higher growth rates and more fearfulness and sociality. Our results reveal that maternal investment increased with age independently of maternal experience, suggesting modification of hormone levels implied in maternal behaviour. Isolated effects of maternal experience should now be assessed in females of the same age. In addition, our results show, for first time in birds, that variations in maternal care directly induce important differences in the behavioural development of chicks. Finally, our results confirm that Japanese quail remains a great laboratory model of avian maternal behaviour and that the way we sample maternal behaviour is highly productive.     

A novel detection strategy for odorant molecules based on controlled bioengineering of rat olfactory receptor I7

In this study, we report a dose-dependent detection of odorant molecules in solution by rat olfactory receptor I7 (OR I7) in its membrane fraction. The OR I7 is immobilized on a gold electrode by multilayer bioengineering based on a mixed self-assembled monolayer and biotin/avidin system, which allows for a well-controlled immobilization of the bioreceptor within its lipid environment. The odorant detection is electronically performed in a quantitative manner by electrochemical impedance spectroscopy (EIS) measurements on samples and controls.     

Immobilization of rhodopsin on a self-assembled multilayer and its specific detection by electrochemical impedance spectroscopy

Rhodopsin, the G protein-coupled receptor (GPCR) which mediates the sense of vision, was prepared from calf eyes and used as receptor enriched membrane fraction. In this study it was immobilized onto gold electrode by two different techniques: Langmuir-Blodgett (LB) and a strategy based on a self-assembled multilayer. We demonstrated that Langmuir and LB films of rhodopsin are not stable. Thus, in this study a new protein multilayer was prepared on gold electrode by building up layer-by-layer a self-assembled multilayer. It is composed of a mixed self-assembled monolayer formed by MHDA and biotinyl-PE, followed by a biotin-avidin system which allows binding of biotinylated antibody specific to rhodopsin. The immobilization of rhodopsin in membrane fraction, by the specific antibody bound previously on self-assembled multilayer, was monitored with electrochemical impedance spectroscopy (EIS). In addition, the specificity and sensitivity of this self-assembled multilayer system to the presence of rhodopsin were investigated. No effect was observed when the system was in contact with olfactory receptor I7 in membrane fraction used for control measurements. All these results demonstrate that rhodopsin can be immobilized efficiently, specifically, quantitatively and stably on gold electrode through the self-assembled multilayer.