Eukaryotic Transcription: What Does It Mean for a Gene to Be ‘on’?

Until recently, transcription could only be observed by measuring mRNA production of cell populations, thus obscuring the kinetics at the level of individual transcription events. A new study now shows that eukaryotic transcription, visualised in individual living cells, occurs in bursts — much as it does in prokaryotes

Protein synthesis molecule by molecule

Since the earliest days of molecular biology it has been known that even a seemingly uniform culture of bacteria is made up of cells very different from each other in terms of their levels of a given protein. This individuality has now finally been quantified at single-molecule resolution, as reported in two recent papers

Is Limited English Proficiency a Barrier to Homeownership?

Nearly 5.3 million US heads of household have limited or no ability to speak English. The connections between race or ethnicity and homeownership have been documented, but there has been little work to explain the relationship between the ability to speak English and homeownership. As homeownership is a primary tool for wealth building and financial stability, it is useful to understand the challenges this population faces in accessing homeownership. This brief first defines and identifies the limited English proficient (LEP) population in the United States. Using descriptive analysis and regression models, we find that at the zip code level, higher rates of limited English proficiency are associated with lower homeownership rates. If we control for other factors that influence homeownership (e.g., income, age, and race or ethnicity), zip codes with the highest concentrations of LEP residents have homeownership rates 5 percentage points lower than zip codes with the median concentration of LEP residents. In other words, limited English proficiency is a barrier to homeownership

Use of board games in higher education literature review

There is a long standing history of mathematical games and puzzles being used to support mathematical thinking and concepts. The Maths Arcade is an initiative designed to provide a unique environment for students to play games in order to communicate with fellow students whilst developing a range of skills. The purpose of this study was to determine how these skills are developed and how they link to different games, we have found the evidence for this through reviewing a variety of sources focussing on game-play. We found that the playing of board games is fundamentally linked to the development of mathematical thinking and skills. These are developed in many ways including trial and improvement and discussion

Quantitative transcription factor binding kinetics at the single-molecule level

We have investigated the binding interaction between the bacteriophage lambda repressor CI and its target DNA using total internal reflection fluorescence microscopy. Large, step-wise changes in the intensity of the red fluorescent protein fused to CI were observed as it associated and dissociated from individually labeled single molecule DNA targets. The stochastic association and dissociation were characterized by Poisson statistics. Dark and bright intervals were measured for thousands of individual events. The exponential distribution of the intervals allowed direct determination of the association and dissociation rate constants, ka and kd respectively. We resolved in detail how ka and kd varied as a function of 3 control parameters, the DNA length L, the CI dimer concentration, and the binding affinity. Our results show that although interaction with non-operator DNA sequences are observable, CI binding to the operator site is not dependent on the length of flanking non-operator DNA.Comment: 34 pages, 10 figures, accepted by Biophysical Journa

Europeanization of sub-arctic environments : perspectives from Norse Greenland's outer fjords

Acknowledgements The authors gratefully acknowledge the financial support of the Leverhulme Trust Footprints on the Edge of Thule Programme Award. ECL acknowledges the support of the Weissman International Internship Program, the Department of Earth and Planetary Sciences and the Department of Anthropology at Harvard. We would also like to thank George McLeod (University of Stirling) for manufacturing soil thin sections.Peer reviewedPostprin

What is news? News values revisited (again)

The deceptively simple question “What is news?” remains pertinent even as we ponder the future of journalism in the digital age. This article examines news values within mainstream journalism and considers the extent to which news values may be changing since earlier landmark studies were undertaken. Its starting point is Harcup and O’Neill’s widely-cited 2001 updating of Galtung and Ruge’s influential 1965 taxonomy of news values. Just as that study put Galtung and Ruge’s criteria to the test with an empirical content analysis of published news, this new study explores the extent to which Harcup and O’Neill’s revised list of news values remain relevant given the challenges (and opportunities) faced by journalism today, including the emergence of social media. A review of recent literature contextualises the findings of a fresh content analysis of news values within a range of UK media 15 years on from the last study. The article concludes by suggesting a revised and updated set of contemporary news values, whilst acknowledging that no taxonomy can ever explain everything

The role of input noise in transcriptional regulation

Even under constant external conditions, the expression levels of genes fluctuate. Much emphasis has been placed on the components of this noise that are due to randomness in transcription and translation; here we analyze the role of noise associated with the inputs to transcriptional regulation, the random arrival and binding of transcription factors to their target sites along the genome. This noise sets a fundamental physical limit to the reliability of genetic control, and has clear signatures, but we show that these are easily obscured by experimental limitations and even by conventional methods for plotting the variance vs. mean expression level. We argue that simple, global models of noise dominated by transcription and translation are inconsistent with the embedding of gene expression in a network of regulatory interactions. Analysis of recent experiments on transcriptional control in the early Drosophila embryo shows that these results are quantitatively consistent with the predicted signatures of input noise, and we discuss the experiments needed to test the importance of input noise more generally.Comment: 11 pages, 5 figures minor correction

Population Fitness and the Regulation of Escherichia coli Genes by Bacterial Viruses

Temperate bacteriophage parasitize their host by integrating into the host genome where they provide additional genetic information that confers higher fitness on the host bacterium by protecting it against invasion by other bacteriophage, by increasing serum resistance, and by coding for toxins and adhesion factors that help the parasitized bacterium invade or evade its host. Here we ask if a temperate phage can also regulate host genes. We find several different host functions that are down-regulated in lysogens. The pckA gene, required for gluconeogenesis in all living systems, is regulated directly by the principal repressor of many different temperate prophage, the cI protein. cI binds to the regulatory region of pckA, thereby shutting down pckA transcription. The pckA regulatory region has target sequences for many other temperate phage repressors, and thus we suggest that down-regulation of the host pckA pathway increases lysogen fitness by lowering the growth rate of lysogens in energy-poor environments, perhaps as an adaptive response to the host predation system or as an aspect of lysogeny that must be offset by down-regulating pckA