Direct observation of sexual competition inDrosophila melanogaster: The mutantWhite in competition with other genotypes

When two types ofDrosophila are in competition, the frequency dependence of mating success routinely is measured in our laboratory by direct observation of mating pairs in Elens-Wattiaux observation chambers. The present experiments concern white mutants (used here as a reference standard) in competition with three other genotypes: wild-type Canton S, giantgt w ^a , and giantgt ^13z /w ⁺ Y/C(1)Dx, y f. From the present observations, the frequency dependence of mating success seems a very common phenomenon: a rare-type sexual advantage exists for females and for males. Sexual activity of male and femalewhite mutants is significantly higher when food is present in the mating chamber. Males of the other strains also are more active in the presence of food. Homogamic matings are more frequent amonggt ^13z /w ⁺ Y/C(1)Dx, y f flies.     

Structural approach of human MAO-A using fold recognition (threading) techniques

The major goal of the present work is to further approach the structure of human monoamine oxidase A (MAO-A). A first partial three-dimensional model of human MAO-A has already been established using secondary structure predictions and fold recognition methods [Wouters and Baudoux, 1998]. In this modeled structure, a segment of the sequence (residues 369-393) located near the covalent linkage to the essential flavin cofactor, and potentially involved in the structure of the active site of the protein, could not be modeled. We here propose a possible fold for that segment, based on threading techniques. The identification of regions of the protein potentially involved in its dimerization was also undertaken by studying hydrophobic areas present at the surface of the structure.     

Meta-analysis of archived DNA microarrays identifies genes regulated by hypoxia and involved in a metastatic phenotype in cancer cells

Background  

Metastasis is a major cancer-related cause of death. Recent studies have described metastasis pathways. However, the exact contribution of each pathway remains unclear. Another key feature of a tumor is the presence of hypoxic areas caused by a lack of oxygen at the center of the tumor. Hypoxia leads to the expression of pro-metastatic genes as well as the repression of anti-metastatic genes. As many Affymetrix datasets about metastasis and hypoxia are publicly available and not fully exploited, this study proposes to re-analyze these datasets to extract new information about the metastatic phenotype induced by hypoxia in different cancer cell lines.     

Identification of FOXP1 deletions in three unrelated patients with mental retardation and significant speech and language deficits

Mental retardation affects 2‐3% of the population and shows a high heritability. Neurodevelopmental disorders that include pronounced impairment in language and speech skills occur less frequently. For most cases, the molecular basis of mental retardation with or without speech and language disorder is unknown due to the heterogeneity of underlying genetic factors. We have used molecular karyotyping on 1523 patients with mental retardation to detect copy number variations (CNVs) including deletions or duplications. These studies revealed three heterozygous overlapping deletions solely affecting the forkhead box P1 (FOXP1) gene. All three patients had moderate mental retardation and significant language and speech deficits. Since our results are consistent with a de novo occurrence of these deletions, we considered them as causal although we detected a single large deletion including FOXP1 and additional genes in 4104 ancestrally matched controls. These findings are of interest with regard to the structural and functional relationship between FOXP1 and FOXP2. Mutations in FOXP2 have been previously related to monogenic cases of developmental verbal dyspraxia. Both FOXP1 and FOXP2 are expressed in songbird and human brain regions that are important for the developmental processes that culminate in speech and language. ©2010 Wiley‐Liss, Inc.     

Cortisol and behavioral responses of working dogs to environmental challenges

This paper's primary objective is to analyse the physiological (cortisol) and behavioral responses of military working dogs (MWD). Dogs (N=27) were submitted twice to environmental challenges (challenge 1 and 2, 20 days in-between) composed of social (training), visual (mobile toy car) and auditory (air blast) stimuli. Cortisol levels decreased back to the baseline after the second challenge. The behavioral observations showed that these MWD were more active, and presented less stereotypic behaviors (pacing, manipulation of the environment) during both visual challenges, whereas half low posture was observed during the first but not during the second visual challenge. The present study shows that this group of MWD still has an adaptation capacity to an environmental challenge (return to baseline of the cortisol levels, a higher posture during the second than at the first challenge). These results are encouraging and indicate that the dogs might have a diminished welfare (i.e. stereotypic behaviors), but are not chronically stressed.     

In Vivo Biomarkers of Estrogenicity: Limitation of Interpretation in Wild Environment

In the literature, multiple sample schemes have been developed to assess the environmental impacts of endocrine-disruptor compounds (EDCs) from sewage treatment plant (STPs). In the present work, the plan study was designed by sampling upstream and downstream wild populations of gudgeons from two STP stations (La Roche and Rochefort, Belgium). Biomarkers of feminization were assayed, such as vitellogenin expression and ovotestis screening. Parameters involved in steroidogenesis (sex steroids and brain aromatase activity) were also investigated to better characterize interactions between living organisms coping with a complex mixture of compounds loaded by treated effluent. Results displayed moderate differences between upstream and downstream populations of wild gudgeons. Moreover, accounted differences have demonstrated the difficulty of characterizing the mixture of compounds to which fish are exposed in the aquatic milieu. Actually, physiological responses were not representative of a particular group of EDC (e.g., estrogenlike compounds) but instead confirm an association between different categories of compounds. Even if powerful biomarkers of estrogenicty were developed, the interpretation of the response profile remains limited through in vivo parameters due to the complex association between compounds of various origins.     

The effects of estrogenic and androgenic endocrine disruptors on the immune system of fish: a review

During the last decade, a number of studies have shown that, in addition to their classically described reproductive function, estrogens and androgens also regulate the immune system in teleosts. Today, several molecules are known to interfere with the sex-steroid signaling. These chemicals are often referred to as endocrine disrupting contaminants (EDCs). We review the growing evidence that these compounds interfere with the fish immune system. These studies encompass a broad range of approaches from field studies to those at the molecular level. This integrative overview improves our understanding of the various endocrine-disrupting processes triggered by these chemicals. Furthermore, the research also explains why fish that have been exposed to EDCs are more sensitive to pathogens during gametogenesis. In this review, we first discuss the primary actions of sex-steroid-like endocrine disruptors in fish and the specificity of the fish immune system in comparison to mammals. Then, we review the known interactions between the immune system and EDCs and interpret the primary effects of sex steroids (estrogens and androgens) and their related endocrine disruptors on immune modulation. The recent literature suggests that immune parameters may be used as biomarkers of contamination by EDCs. However, caution should be used in the assessment of such immunotoxicity. In particular, more attention should be paid to the specificity of these biomarkers, the external/internal factors influencing the response, and the transduction pathways induced by these molecules in fish. The use of the well-known mammalian models provides a useful guide for future research in fish.     

Larval behavioral response to environmental ethanol in relation to alcohol dehydrogenase activity level inDrosophila melanogaster

FourDrosophila melanogaster strains characterized by different alcohol dehydrogenase (ADH) activity levels are compared for the behavior of their larvae in response to environmental ethanol. The larvae are attracted by ethanol if they are able to convert rapidly the acetaldehyde resulting from the metabolic oxidation of ethanol. A comparison is made with the oviposition behavior of flies of the same strains in response to environmental ethanol. A similarity between oviposition behavior and larval behavior is found only for a strain lacking both alcohol dehydrogenase and aldehyde oxidase (AO).