Niveaux hormonaux plasmatiques de poules albinos (sal-c) et non albinos (S)

Des poules albinos (mutation s al-c) et non-albinos (colorées) de même origine ont été comparées pour des niveaux plasmatiques hormonaux, triiodothyronine (T3), thyroxine (T4), hormone de croissance (GH) et corticostérone, avant l’entrée en ponte puis après 3 à 4 mois de ponte. Le rapport T3/T4 était plus élevé chez les poules albinos que chez les non-albinos aux 2 âges; cette différence s’approche de la signification après l’entrée en ponte. La variance intra-génotype de ce rapport est plus élevée pour les poules s al-c que pour les non-albinos (P < 0,01). D’autre part, le taux de l’hormone de croissance ne diffère pas entre génotypes avant l’entrée en ponte, mais en période de ponte il est significativement plus élevé chez les poules s al. Il existe donc certaines différences dans l’équilibre hormonal des 2 génotypes. On peut espérer que ceci aide à l’interprétation des effets trouvés associés au gène albinos sur la production d’oeufs.Albino (s al-c) and non-albino (colored) hens from the same origin were compared for several plasmatic hormonal levels (triiodothyronine (T3), thyroxine (T4), growth hormone (GH), and corticosterone) before the onset of laying and after 3-4 months of production. The T3/T4 ratio was higher among albino than among non-albino females at the 2 ages; this difference approached significance after sexuaL maturity. The within-genotype variance of this ratio was higher for s al-c hens than for non-albino ones (P<0.01). On the other hand, the GH level did not differ between the 2 genotypes before the onset of laying, but during laying it was significantly higher for the s al-c females. There are therefore some differences in the general hormonal balance of the 2 genotypes. It is hoped that this may help in an interpretation of the effects on egg production associated with the albino gene

Physiological studies on the sex-linked dwarfism of the fowl: a review on the search for the gene's primary effect

International audienc

Gene expression profiling of Leishmania (Leishmania) donovani: overcoming technical variation and exploiting biological variation

Gene expression profiling is increasingly used in the field of infectious diseases for characterization of host, pathogen and the nature of their interaction. The purpose of this study was to develop a robust, standardized method for comparative expression profiling and molecular characterization of Leishmania donovani clinical isolates. The limitations and possibilities associated with expression profiling in intracellular amastigotes and promastigotes were assessed through a series of comparative experiments in which technical and biological parameters were scrutinized. On a technical level, our results show that it is essential to use parasite harvesting procedures that involve minimal disturbance of the parasite's environment in order to ‘freeze' gene expression levels instantly; this is particularly a delicate task for intracellular amastigotes and for specific ‘sensory' genes. On the biological level, we demonstrate that gene expression levels fluctuate during in vitro development of both intracellular amastigotes and promastigotes. We chose to use expression-curves rather than single, specific, time-point measurements to capture this biological variation. Intracellular amastigote protocols need further refinement, but we describe a first generation tool for high-throughput comparative molecular characterization of patients' isolates, based on the changing expression profiles of promastigotes during in vitro differentiatio

MS in South Asians in England: early disease onset and novel pattern of myelin autoimmunity.

BACKGROUND: Epidemiological studies describe a latitude gradient for increased MS prevalence and a preponderance of disease in Caucasian individuals. However, individuals from other ethnic backgrounds and low-risk regions can acquire a raised risk through migration. Nearly a fifth of the London population is of Asian/Asian-British origin and a significant proportion of referrals are from this group. METHODS: We investigated whether there were differences in timing, presentation, severity, and immunology of disease (with respect to CD4 myelin epitope recognition) between individuals in London with MS who were either of S. Asian or Caucasian origin. Individuals of S. Asian origin with MS were compared with healthy S. Asian controls, individuals with MS and of Caucasian origin and Caucasian controls. RESULTS: Age at MS onset is significantly lower in the S. Asian group, attributable to earlier onset specifically in UK-born individuals, though clinical presentation is similar. Analysis of CD4 autoimmunity to myelin antigens shows disease in S. Asian individuals to encompass recognition of novel epitopes; immunity to MBP116-130 in S. Asian individuals was highly disease-specific. CONCLUSIONS: These findings emphasize the need to define disease profiles across ethnicities and identify environmental triggers conferring acquired risk. Such findings must inform choices for immunotherapeutic interventions suitable for all, across ethnicities

Comparison of gene expression patterns among Leishmania braziliensis clinical isolates showing a different in vitro susceptibility to pentavalent antimony

Introduction. Evaluation of Leishmania drug susceptibility depends on in vitro SbV susceptibility assays, which are labour-intensive and may give a biased view of the true parasite resistance. Molecular markers are urgently needed to improve and simplify the monitoring of SbV-resistance. We analysed here the gene expression profile of 21 L. braziliensis clinical isolates in vitro defined as SbV-resistant and -sensitive, in order to identify potential resistance markers. Methods. The differential expression of 13 genes involved in SbV metabolism, oxidative stress or housekeeping functions was analysed during in vitro promastigote growth. Results. Expression profiles were up-regulated for 5 genes only, each time affecting a different set of isolates (mosaic picture of gene expression). Two genes, ODC (ornithine decarboxylase) and TRYR (trypanothione reductase), showed a significantly higher expression rate in the group of SbV-resistant compared to the group of SbV-sensitive parasites (P<0·01). However, analysis of individual isolates showed both markers to explain only partially the drug resistance. Discussion. Our results might be explained by (i) the occurrence of a pleiotropic molecular mechanism leading to the in vitro SbV resistance and/or (ii) the existence of different epi-phenotypes not revealed by the in vitro SbV susceptibility assays, but interfering with the gene expression pattern

Real-time PCR/MCA assay using fluorescence resonance energy transfer for the genotyping of resistance related DHPS-540 mutations in Plasmodium falciparum

BACKGROUND: Sulphadoxine-pyrimethamine has been abandoned as first- or second-line treatment by most African malaria endemic countries in favour of artemisinin-based combination treatments, but the drug is still used as intermittent preventive treatment during pregnancy. However, resistance to sulphadoxine-pyrimethamine has been increasing in the past few years and, although the link between molecular markers and treatment failure has not been firmly established, at least for pregnant women, it is important to monitor such markers. METHODS: This paper reports a novel sensitive, semi-quantitative and specific real-time PCR and melting curve analysis (MCA) assay using fluorescence resonance energy transfer (FRET) for the detection of DHPS-540, an important predictor for SP resistance. FRET/MCA was evaluated using 78 clinical samples from malaria patients and compared to PCR-RFLP. RESULTS: Sixty-two samples were in perfect agreement between both assays. One sample showed a small wild type signal with FRET/MCA that indicates a polyclonal infection. Four samples were not able to generate enough material in both assays to distinguish mutant from wild-type infection, six samples gave no signal in PCR-RFLP and five samples gave no amplification in FRET/MCA. CONCLUSION: FRET/MCA is an effective tool for the identification of SNPs in drug studies and epidemiological surveys on resistance markers in general and DHPS-540 mutation in particular