Transcription occurs in stochastic bursts. Early models based upon RNA hybridisation studies suggest bursting dynamics arise from alternating inactive and permissive states. Here we investigate bursting mechanism in live cells by quantitative imaging of actin gene transcription, combined with molecular genetics, stochastic simulation and probabilistic modelling. In contrast to early models, our data indicate a continuum of transcriptional states, with a slowly fluctuating initiation rate converting the gene between different levels of activity, interspersed with extended periods of inactivity. We place an upper limit of 40 s on the lifetime of fluctuations in elongation rate, with initiation rate variations persisting an order of magnitude longer. TATA mutations reduce the accessibility of high activity states, leaving the lifetime of on- and off-states unchanged. A continuum or spectrum of gene states potentially enables a wide dynamic range for cell responses to stimuli.DOI: http://dx.doi.org/10.7554/eLife.13051.001

Transcription of genes can be discontinuous, occurring in pulses or bursts. It is not clear how properties of transcriptional pulses vary between different genes. We compared the pulsing of five housekeeping and five developmentally induced genes by direct imaging of single gene transcriptional events in individual living Dictyostelium cells. Each gene displayed its own transcriptional signature, differing in probability of firing and pulse duration, frequency, and intensity. In contrast to the prevailing view from both prokaryotes and eukaryotes that transcription displays binary behavior, strongly expressed housekeeping genes altered the magnitude of their transcriptional pulses during development. These nonbinary "tunable" responses may be better suited than stochastic switch behavior for housekeeping functions. Analysis of RNA synthesis kinetics using fluorescence recovery after photobleaching implied modulation of housekeeping-gene pulse strength occurs at the level of transcription initiation rather than elongation. In addition, disparities between single cell and population measures of transcript production suggested differences in RNA stability between gene classes. Analysis of stability using RNAseq revealed no major global differences in stability between developmental and housekeeping transcripts, although strongly induced RNAs showed unusually rapid decay, indicating tight regulation of expression.transcriptional bursting | RNA turnover | stochastic gene expression T ranscription is not adequately described by the smooth, seamless process implied by standard measures of RNA level. Within individual cells, transcription occurs as a series of irregular pulses, interspersed by long, irregular periods of inactivity. Pulsing (or bursting) is a fundamental feature of transcription, conserved from prokaryotes to mammalian cells (1-5). These phenomena have strong implications for our understanding of transcriptional mechanism and may provide a major source of stochasticity in gene expression (6), a driver of cell diversity in differentiation and disease (7,8). However, it is unclear how pulsing behaves for different genes with different functional properties.Pulsing dynamics, and therefore deeper understanding of underlying transcriptional mechanics and regulation of different genes, are masked when averaged over millions of dead cells, as occurs with standard bulk RNA measurement techniques, from Northern blotting to RNA sequencing (RNAseq). The readout from these methods also has a variable contribution from RNA stability. Although strong inferences can be made from heterogeneities in transcript number using hybridization against RNA in single cells (RNA-FISH) (9-11), an erroneous inference of strong transcription from both bulk and fixed-cell RNA techniques emerges if RNA is stable. To appreciate how transcription is regulated and how the process differs between different genes, it is crucial to look at the process itself in living cells at the singlegene level. Live-cell methods using fluorescent protein...

This article aimed to analyse the outcome of self-management randomised control trials and their impact upon chronic obstructive pulmonary disease patients' health outcomes using meta-analysis approach. PubMed, Scopus, CINAHL, Web of Science databases and Cochrane Library, were searched for articles between 1990 and December 2015 by two researchers. Self-management programs significantly improved patients' quality of life across all domains of the St George Respiratory Questionnaire (SGRQ) (activity -2.21 (95% CI: -3.61 to -0.80), p = 0.002; impact -3.30 (95% CI: -5.28 to -1.32), p = 0.001; symptoms -3.12 (95% CI: -4.94 to -1.03), p = 0.001; total -3.32 (95% CI: -4.60 to -2.04), p < 0.001), the six-minute walk test (-30.50 (95% CI: 3.32 to 57.68), p = 0.028), and across three domains of the chronic obstructive pulmonary disease self-efficacy scale (negative effect -1.22 (95% CI: -2.31 to -0.14), p = 0.027; physical exertion -1.27 (95% CI: -2.52 to -0.02), p = 0.047; behavioural risk factors -0.58 (95% CI: -0.99 to -0.16), p = 0.007). Subgroup analyses revealed that chronic obstructive pulmonary disease education (p < 0.01) was the strongest component with improvements on all aspects of the SGRQ and the six-minute walk test. Providing an exacerbation action plan significantly improved SGRQ activity and impact scores whilst exercise information had a positive effect on activity and symptom scores (p < 0.05). Interventions with a duration of less than five weeks (p < 0.05) significantly improved symptom and activity scores, in addition to the number of patient hospital admissions. Thus, self-management interventions are effective at improving the health outcomes of chronic obstructive pulmonary disease patients, especially when disease education is provided.

Several amyloidogenic proteins including insulin, β-lactoglobulin and albumin, form spherulites in vitro under non-physiological conditions. These micrometer-sized, roughly spherical structures are composed of ordered arrays of amyloid fibrils in radial arrangements which, characteristically, show a typical Maltese cross pattern of light extinction under the polarizing microscope. The physiological significance of amyloid spherulites is unknown though in Alzheimer's disease senile plaques composed primarily of β sheets of Aβ 42 have, very occasionally, been shown to give a Maltese cross pattern of light extinction under crossed polarisers. Herein we describe the first observation of the formation in vitro of spherulites of Aβ 42 . They were formed under nearphysiological conditions in which the β sheet conformation of preformed aggregates of Aβ 42 had been abolished following the addition of an excess of copper. Incubation of these preparations at 37°C for up to 9 months resulted in the formation of globular structures, 5 -20 μm in diameter, which exhibited a Maltese cross pattern of light extinction typical of spherulites. Near-identical spherulitic structures were also observed in abundance in 30 μm thick sections of Alzheimer's disease brain tissue. Synchrotron x-ray fluorescence showed that the location of these spherulites in AD tissue coincided with locally elevated concentrations of tissue copper. The formation in vitro of spherulites of Aβ 42 which morphologically appeared analogous to spherulitic structures observed in vivo strongly supports the hypothesis that spherulites and senile plaques in AD tissue are one and the same structures and that their ultimate formation may involve copper.