How to Regulate a Gene: To Repress or to Activate?

Gene-expression responses to an input can depend on growth conditions; in this issue, Sasson et al. (2012) show that this dependence is lower when the input results in a high degree of promoter occupancy

Teken en Visie:De wijsgerig-anthropologische grondslagen van het teken-gebruik, speciaal in de exacte wetenschappen

One of the most important problems in the philosophy of science is formed by the question, to which extent scientific formulas and signs can tell us something about reality, and if in general our theories can approximate reality as it is in itself. This problem of truth in science is the problem of the relation between signs, theory and reality. ... Zie: Summary

Differential stoichiometry among core ribosomal proteins

Understanding the regulation and structure of ribosomes is essential to understanding protein synthesis and its deregulation in disease. While ribosomes are believed to have a fixed stoichiometry among their core ribosomal proteins (RPs), some experiments suggest a more variable composition. Testing such variability requires direct and precise quantification of RPs. We used mass-spectrometry to directly quantify RPs across monosomes and polysomes of mouse embryonic stem cells (ESC) and budding yeast. Our data show that the stoichiometry among core RPs in wild-type yeast cells and ESC depends both on the growth conditions and on the number of ribosomes bound per mRNA. Furthermore, we find that the fitness of cells with a deleted RP-gene is inversely proportional to the enrichment of the corresponding RP in polysomes. Together, our findings support the existence of ribosomes with distinct protein composition and physiological function.Comment: 31 pages, 8 figure

Allele-specific detection of single mRNA molecules in situ

We describe a method for fluorescent in situ identification of individual mRNA molecules, allowing quantitative and accurate measurements of allele-specific transcripts that differ by only a few nucleotides, in single cells. By using a combination of allele-specific and non-allele-specific probe libraries, we achieve over 95% detection accuracy. We investigate the allele-specific stochastic expression of the pluripotency factor Nanog in murine embryonic stem cells

Карти роботи Йогана Баптиста Гомана в збірці Національного музею історії України

Стаття присвячена відомому німецькому картографу XVIII ст. Й.Б.Гоману і його роботам, що зберігаються в фондах Національного музею історії України. Ці карти мають виняткове значення як для дослідників, що займаються вивченням проблем з історії України та Європи, так і для тих вчених, які досліджують питання історії картографічної науки на теренах Європи.The article is dedicated to a famous German cartographer of the 18th century J.B. Homanno and his works, that belong to the fund collections of National Museum of the History of Ukraine. These maps are of exceptional importance for the researchers who deal with the history of Ukraine and Europe, and equally for those scientists who study the problems of the history of European cartography

Single molecule fluorescent in situ hybridization (smFISH) of C. elegans worms and embryos

In C. elegans, the expression pattern of a gene provides important clues to understanding its biological function. To accurately depict endogenous transcriptional activity, a highly sensitive method is required to measure transcript levels in the intact tissue across various developmental stages. Conventional RNA in situ hybridization methods using hapten- (biotin or digoxygenin) labeled RNA probes rely on antibody binding for visualization, and are thus only semi-quantitative at best (Raap et al. 1995; Levsky et al. 2003). Additionally, hapten-labeled probes are prone to diffuse localization (when conjugated with alkaline phosphatase), low sensitivity (when conjugated with fluorescent molecules), and non-specific probe binding. Here, we introduce a recently developed mRNA in situ hybridization method (Raj et al. 2008) that circumvents the above difficulties to give single molecule resolution of transcript detection