Air pollution-induced placental epigenetic alterations in early life: a candidate miRNA approach

Particulate matter (PM) exposure during in utero life may entail adverse health outcomes in later-life. Air pollution's adverse effects are known to alter gene expression profiles, which can be regulated by microRNAs (miRNAs). We investigate the potential influence of air pollution exposure in prenatal life on placental miRNA expression. Within the framework of the ENVIRONAGE birth cohort, we measured the expression of six candidate miRNAs in placental tissue from 210 mother-newborn pairs by qRT-PCR. Trimester-specific PM_2.5 exposure levels were estimated for each mother's home address using a spatiotemporal model. Multiple regression models were used to study miRNA expression and in utero exposure to PM_2.5 over various time windows during pregnancy. The placental expression of miR-21 (?33.7%, 95% CI: ?53.2 to ?6.2, P = 0.022), miR-146a (?30.9%, 95% CI: ?48.0 to ?8.1, P = 0.012) and miR-222 (?25.4%, 95% CI: ?43.0 to ?2.4, P = 0.034) was inversely associated with PM_2.5 exposure during the 2nd trimester of pregnancy, while placental expression of miR-20a and miR-21 was positively associated with 1st trimester exposure. Tumor suppressor phosphatase and tensin homolog (PTEN) was identified as a common target of the miRNAs significantly associated with PM exposure. Placental PTEN expression was strongly and positively associated (+59.6% per 5 µg/m³ increment, 95% CI: 26.9 to 100.7, P < 0.0001) with 3rd trimester PM_2.5 exposure. Further research is required to establish the role these early miRNA and mRNA expression changes might play in PM-induced health effects. We provide molecular evidence showing that in utero PM_2.5 exposure affects miRNAs expression as well as its downstream target PTEN.     

Perturbation and delayed recovery of the reed invertebrate assemblage in Camargue marshes sprayed with Bacillus thuringiensis israelensis

Bacillus thuringiensis var. israelensis (Bti) is the most commonly used larvicide to control mosquitoes worldwide. Considered as nontoxic to most organisms, Bti can nevertheless cause trophic perturbations to natural communities by reducing the abundance of Chironomidae, which are a key element of wetland food webs. Since August 2006, up to 8400 of the 33 000 ha of mosquito larval biotopes in the Camargue (Rhône delta, in southern France), are monitored by a public agency and Bti‐sprayed (aqueous solution of VectoBac 12AS at 2.5 L/ha) whenever mosquito larvae (Ochlerotatus caspius and Oc. detritus) appeared in water bodies. This resulted in 30–50 aerial treatments/year, in addition to ground spraying of unknown frequency. The sprayed habitats include Phragmites australis reedbeds, which support a specific avifauna of conservation concern. We compared the abundance of invertebrate prey available to passerine birds at treated and control sites relative to the predicted values based on hydrology over a 9‐year period. Food available to reed passerines was significantly reduced at treated areas, translating into a 34% decrease in breeding birds based on predictive modeling. The most affected arthropods were Diptera, Aranaea, Coleoptera, and Hymenoptera. No cumulative effects were observed over time, but the recovery of the invertebrate assemblage after the cessation of mosquito control was delayed due to Bti spore persistence and proliferation in the sediments. While hydrology remains a prime factor influencing primary and secondary productivity of the Camargue reed marshes, Bti spraying had significant negative effects on animal communities at several trophic levels.     

Palaeobiogeographic implications of the first report of the eocrinoid genus Ascocystites Barrande (Echinodermata,Blastozoa) in the Upper Ordovician of the Ougarta Range (Western Algeria)

Several specimens of the genus Ascocystites (Blastozoa, Eocrinoidea) are described for the first time in Late Ordovician deposits (Bou M’Haoud Formation) from the Ougarta Range, Algeria. This genus was previously known in Darriwilian–Sandbian deposits of four other areas of the Mediterranean Province (Czech Republic, France, Morocco and Portugal). The Algerian material completes its palaeobiogeographic distribution in the peri-Gondwanan area, restricted in shallow water settings.     

SOX9 is a potent activator of the chondrocyte-specific enhancer of the pro alpha1(II) collagen gene.

The identification of mutations in the SRY-related SOX9 gene in patients with campomelic dysplasia, a severe skeletal malformation syndrome, and the abundant expression of Sox9 in mouse chondroprogenitor cells and fully differentiated chondrocytes during embryonic development have suggested the hypothesis that SOX9 might play a role in chondrogenesis. Our previous experiments with the gene (Col2a1) for collagen II, an early and abundant marker of chondrocyte differentiation, identified a minimal DNA element in intron 1 which directs chondrocyte-specific expression in transgenic mice. This element is also a strong chondrocyte-specific enhancer in transient transfection experiments. We show here that Col2a1 expression is closely correlated with high levels of SOX9 RNA and protein in chondrocytes. Our experiments indicate that the minimal Col2a1 enhancer is a direct target for Sox9. Indeed, SOX9 binds to a sequence of the minimal Col2a1 enhancer that is essential for activity in chondrocytes, and SOX9 acts as a potent activator of this enhancer in cotransfection experiments in nonchondrocytic cells. Mutations in the enhancer that prevent binding of SOX9 abolish enhancer activity in chondrocytes and suppress enhancer activation by SOX9 in nonchondrocytic cells. Other SOX family members are ineffective. Expression of a truncated SOX9 protein lacking the transactivation domain but retaining DNA-binding activity interferes with enhancer activation by full-length SOX9 in fibroblasts and inhibits enhancer activity in chondrocytes. Our results strongly suggest a model whereby SOX9 is involved in the control of the cell-specific activation of COL2A1 in chondrocytes, an essential component of the differentiation program of these cells. We speculate that in campomelic dysplasia a decrease in SOX9 activity would inhibit production of collagen II, and eventually other cartilage matrix proteins, leading to major skeletal anomalies.     

Scrounger numbers and the inhibition of social learning in pigeons

Social foraging can inhibit the learning and performance of food-finding behaviours. Confusion, overshadowing and frequency-dependent payoffs may all contribute to the inhibition, but standard experimental procedures make the separation of these effects difficult. In this study, we combine characteristics of cage and aviary experiments and present either a single naive pigeon or groups of three naive pigeons with a pre-trained producer opening an apparatus in an aviary. All naive birds scrounged on the 3456 openings they witnessed. In a post-test given in the absence of other birds, all single scroungers opened the apparatus, but only one of the group-scrounging pigeons did. Scrounger numbers appear to play an important role in the inhibition of food-finding behaviour, suggesting that confusion is a major component of learning in a social context.     

QTLs for a component of partial resistance to cucumber mosaic virus in pepper: restriction of virus installation in host-cells

 Ninety four doubled-haploid (DH) lines obtained from the F₁ between Perennial, a cucumber mosaic virus (CMV)-partially resistant Capsicum annuum line, and Yolo Wonder, a CMV-susceptible C. annuum line, were analysed with 138 markers including mostly RFLPs and RAPDs. Clustering of RAPD markers was observed on five linkage groups of the intraspecific linkage map. These clusters could correspond to the centromeric regions of pepper chromosomes. The same progenies were evaluated for restriction of CMV installation in pepper cells in order to map quantitative trait loci (QTLs) controlling CMV resistance. This component of partial resistance to CMV was quantitatively assessed using a CMV strain that induced necrotic local lesions on the inoculated leaves. The number of local lesions gave an estimation of the density of the virus-infection sites. Genotypic variance among the DH lines was highly significant for the number of local lesions, and heritability was estimated to be 0.94. Using both analysis of variance and non-parametric tests, three genomic regions significantly affecting CMV resistance were detected on chromosomes Noir, Pourpre and linkage group 3, together explaining 57% of the phenotypic variation. A digenic epistasis between one locus that controlled significant trait variation and a second locus that by itself had no demonstrable effect on the trait was found to have an effect on CMV resistance. For each QTL, the allele from Perennial was associated with an increased resistance. Implications of QTL mapping in marker-based breeding for CMV resistance are discussed. Received: 16 September 1996     

Defense response genes co-localize with quantitative disease resistance loci in pepper

Functional bases of polygenically inherited disease resistance are still unknown. In recent years, molecular dissection of polygenic resistance has led to the identification and location of quantitative trait loci (QTLs) on many plant genetic linkage maps. This process is a pre-requisite for resistance QTL characterization at a molecular and functional level. Here, we report the use of a candidate gene approach based on the hypothesis that some resistance QTLs previously mapped in pepper may correspond to defense response (DR) genes. Degenerate oligonucleotide primers were designed for conserved regions of two DR gene families: pathogenesis-related proteins (PR) of class 2 (β-1,3-glucanase) and PR proteins of class 5 (antifungal activity). Cloned pepper PCR-products as well as other solanaceous DR gene families were used as RFLP probes for mapping in three intraspecific maps of the pepper genome. A total of 12 probes out of 23 were positioned and generated 16 loci. Some DR probes revealed multiple gene copies in the pepper genome (PR5, β-1,3-glucanase, chitinase and Glutathione S-transferase). Genes encoding acidic and basic β-1,3-glucanases were clustered on linkage group (LG) P1a, whereas genes encoding chitinases occurred on several LGs (P1b, P2a and P5). A class-III chitinase gene co-localized with a major-effect QTL controlling resistance to Phytophthora capsici on LG P5. PR4, PR2 and PR10 loci mapped within the region of resistance QTLs to P. capsici (LG P1b), Potato virus Y (LG P1a) and Potyvirus E (LG P3), respectively. A digenic interaction between a PR4 and a PR2 loci explained a large effect (35%) of the resistance to Potyvirus E.     

Cultural Diffusion of a Novel Food-finding Behaviour in Urban Pigeons: an Experimental Field Test

The cultural diffusion of a novel food-finding behaviour, piercing the paper cover of a box containing seed, was experimentally provoked in two flocks of pigeons (Columba livia): a closed aviary flock and an open urban flock. In the urban flock, piercing behaviour spread to 24 previously naive individuals. The rate of cultural diffusion was more rapid in the urban flock than in the aviary. In both situations, many individuals simply fed from the discoveries of birds that pierced, but this effect slowed diffusion less in the open urban flock because experienced piercers left the flock and naive birds entered it. Individual trial-and-error learning and natural shaping can be ruled out as mechanisms of diffusion in the present case.     

The social transmission of a food-finding technique in pigeons: what is learned?

Experimentally-naive pigeons (Columba livia) were exposed to varying amounts of socially transmitted information needed for solving a food-finding problem. Observer pigeons that saw a trained bird (model) piercing the paper covering a food box and eating were able to solve the problem faster and more efficiently than pigeons that only saw the model eating but not piercing. This result held whether observer performance was simultaneous or deferred with respect to the model's demonstration. Pigeons that saw the model piercing but not eating showed almost no tendency to copy. These results suggest that copying was dependent upon observer recognition of the fact that the model was getting a food reward, and that pigeons were capable of learning aspects of the piercing technique by observation rather than by trial and error.     

The invasive red swamp crayfish as a predictor of Eurasian bittern density in the Camargue, France

Few data exist on the relationships between food levels and breeding density of the Eurasian bittern Botaurus stellaris , a vulnerable species of high-priority concern in Europe. Concurrent data were obtained on male bittern density and relative food abundance over a 3-year period in two wetlands totalling 2500 ha of Mediterranean reed marsh enclosing 25% of the French bittern population. Food abundance was estimated by sampling up to 25 hydrological units using a beach seine in early June of 2002, 2003 and 2004. The density of booming males in each hydrological unit was obtained by point counts and acoustic triangulation in May of the same years. The impact of food abundance on male bittern density was assessed by general regression models using a forward stepwise procedure with mosquitofish Gambusia affinis , carp Cyprinus carpio , other fish species, amphibians, red swamp crayfish Procambarus clarkii and other invertebrates as prey groups. Of these, only to crayfish abundance was bittern density related, contributing to 45% of the variance observed. When the impact of water level was taken into account, the relative abundance of crayfish explained 56% of the inter-annual differences in bittern density. Because crayfish are rich in calcium and well adapted to fluctuating hydroperiods alternating with drought intervals, they provide a good food source for the bitterns throughout the breeding season at the study sites. The loss of diversity and degradation reported from macrophyte-dominated marshes following crayfish invasion does not seem to apply to reed-dominated wetlands. It is further suggested that the recent increase in bittern numbers in the Camargue, while other French populations were decreasing, could in part be related to red swamp crayfish abundance.