Chemotypic variation explaining traditional selection of tropical root crops in Vanuatu, South Pacific

Understanding chemical variations in edible plant organs is essential for a better understanding of crop genetic diversity in traditional fields as well as for selection. Among tropical root crop species, high variation has been shown in the composition and content of isoprenoids and flavonoids. The purpose of this work was to identify relations between local preferences, primary compound and secondary metabolite contents, to attempt characterizing a good cultivar according to traditional customs and knowledge. A core-collection of about 500 cultivars was built to represent the widest agro-morphological variability, and analyses were made for percentage of dry matter, starch, minerals, cellulose, proteins and total sugars. In terms of primary compounds, very high coefficients of variation were found for protein, total sugar, cellulose and mineral contents, while starch exhibited the lowest variation. Starch content was always positively correlated with dry matter content, whereas it was negatively correlated with protein, mineral, total sugar and cellulose contents significant at 0.01% level. Through blind tests on organoleptic properties, local consumers were shown to prefer consuming their national dish with high starch and dry matter content, giving a particular cultivar high value in the eyes of local consumers. In contrast, preferences for daily consumption of boiled or roasted tubers were linked to average starch content, indicating great opportunities for improvement of others primary compound contents. Interestingly, isoprenoids content were strongly correlated to flavonol and flavanol contents among yam species, while phenolic acids content exhibited positive correlation with anthocyanins. This work suggests biofortification opportunities in isoprenoids and flavonoids content by colour-based selection. The database we established will help breeders improve micronutrient contents and health benefits of such staple foods. (Texte intégral

Transposer de l'animal à l'humain : les modèles pharmacocinétiques physiologiques

On utilise souvent la dose administrée aux animaux, ou le niveau environnemental, d'exposition des populations humaines, pour décrire la relation entre dose et risque de survenue d'effets toxiques. Cette dosimétrie suppose que la dose interne, effective, est strictement proportionnelle à l'exposition externe ou à la quantité de produit administré

Human immunodeficiency virus type 1 incidence among blood donors in France, 1992 through 2006: use of an immunoassay to identify recent infections

BACKGROUND: In France, blood donations found to be positive for the presence of human immunodeficiency virus type 1 (HIV-1) are further tested to detect recent infections (≤180 days) using an enzyme immunoassay (EIA-RI) developed in 2002. The characteristics of recently infected donors, estimates of HIV-1 incidence, and the residual risk of transfusion-transmitted HIV-1 are presented, in both first-time and repeat donors. STUDY DESIGN AND METHODS: Of the 1027 donations found to be HIV-1–positive between 1992 and 2006, a total of 459 could be retrospectively tested with the EIA-RI. Multivariate analysis was performed to determine the donor characteristics associated with recent infection. Incidence rates and residual risk obtained with the EIA-RI were compared to classical cohort estimates derived from repeat donor histories. RESULTS: Of the 459 HIV-1–positive donors studied, 105 (22.9%; 95% confidence interval [CI], 19.2-27.0) were identified as recently infected. Factors independently associated with recent infection were repeat donor status (adjusted odds ratio [AOR], 4.0; 95% CI, 2.4-6.9) and non-B subtypes (AOR, 2.0; 95% CI, 1.2-3.6). Incidence decreased from 4.3 (95% CI, 1.9-9.4) in 1992 through 1994 to 1.3 (95% CI, 0.6-2.8) per 105 in 2004 through 2006 in first-time donors and from 3.2 (95% CI, 2.0-5.0) to 0.8 (95% CI, 0.4-1.4) per 105 in repeat donors. Incidence and residual risk estimates were similar to those obtained with the classical cohort method. CONCLUSION: This study suggests that the EIA-RI can be used to estimate HIV-1 incidence in a population with low HIV incidence. The estimated HIV-1 incidence in the blood donor population confirms the extremely low risk (1 in 3,350,000 donations) of HIV-infected blood donations entering the blood supply in France

New Opportunities in Metabolomics and Biochemical Phenotyping for Plant Systems Biology

Pollution contro

Chapter New Opportunities in Metabolomics and Biochemical Phenotyping for Plant Systems Biology

Pollution contro

Conservation of the links between gene transcription and chromosomal organization in the highly reduced genome of Buchnera aphidicola

<p>Abstract</p> <p>Background</p> <p>Genomic studies on bacteria have clearly shown the existence of chromosomal organization as regards, for example, to gene localization, order and orientation. Moreover, transcriptomic analyses have demonstrated that, in free-living bacteria, gene transcription levels and chromosomal organization are mutually influenced. We have explored the possible conservation of relationships between mRNA abundances and chromosomal organization in the highly reduced genome of <it>Buchnera aphidicola</it>, the primary endosymbiont of the aphids, and a close relative to <it>Escherichia coli</it>.</p> <p>Results</p> <p>Using an oligonucleotide-based microarray, we normalized the transcriptomic data by genomic DNA signals in order to have access to inter-gene comparison data. Our analysis showed that mRNA abundances, gene organization (operon) and gene essentiality are correlated in <it>Buchnera </it>(i.e., the most expressed genes are essential genes organized in operons) whereas no link between mRNA abundances and gene strand bias was found. The effect of <it>Buchnera </it>genome evolution on gene expression levels has also been analysed in order to assess the constraints imposed by the obligate symbiosis with aphids, underlining the importance of some gene sets for the survival of the two partners. Finally, our results show the existence of spatial periodic transcriptional patterns in the genome of <it>Buchnera</it>.</p> <p>Conclusion</p> <p>Despite an important reduction in its genome size and an apparent decay of its capacity for regulating transcription, this work reveals a significant correlation between mRNA abundances and chromosomal organization of the aphid-symbiont <it>Buchnera</it>.</p