Combination of novel and public RNA-seq datasets to generate an mRNA expression atlas for the domestic chicken

Background: The domestic chicken (Gallus gallus) is widely used as a model in developmental biology and is also an important livestock species. We describe a novel approach to data integration to generate an mRNA expression atlas for the chicken spanning major tissue types and developmental stages, using a diverse range of publicly-archived RNA-seq datasets and new data derived from immune cells and tissues. Results: Randomly down-sampling RNA-seq datasets to a common depth and quantifying expression against a reference transcriptome using the mRNA quantitation tool Kallisto ensured that disparate datasets explored comparable transcriptomic space. The network analysis tool Graphia was used to extract clusters of co-expressed genes from the resulting expression atlas, many of which were tissue or cell-type restricted, contained transcription factors that have previously been implicated in their regulation, or were otherwise associated with biological processes, such as the cell cycle. The atlas provides a resource for the functional annotation of genes that currently have only a locus ID. We cross-referenced the RNA-seq atlas to a publicly available embryonic Cap Analysis of Gene Expression (CAGE) dataset to infer the developmental time course of organ systems, and to identify a signature of the expansion of tissue macrophage populations during development. Conclusion: Expression profiles obtained from public RNA-seq datasets - despite being generated by different laboratories using different methodologies - can be made comparable to each other. This meta-analytic approach to RNA-seq can be extended with new datasets from novel tissues, and is applicable to any species

Rôle de l'émission stimulée dans la fluorescence

Stimulated light can play an important part in luminescence, not only in the resonant cavities of masers and lasers, but generally. We try to establish here new differential equations for simple fluorescence and for resonance.L'existence d'une émission stimulée modifie profondément les équations différentielles de la luminescence, non seulement dans le cas des cavités résonnantes, mais d'une façon générale. On cherche ici à établir les nouvelles équations relatives aux fluorescences simples et aux résonances

Un porte-échantillon assurant l'uniformité de température des poudres luminescentes

Description of a sample-holder for researches in thermoluminescence of crystalline powders ; it assures good uniformity of temperature at the upper surface of the powder, giving a better précision than cylindrical holders.On décrit un porte-échantillon, destiné aux recherches sur la thermoluminescence des poudres cristallines qui, en assurant l'uniformité de la température à la surface de l'échantillon, permet d'obtenir une meilleure précision que par l'emploi de cavités cylindriques