Stochasticity of gene products from transcriptional pulsing

Transcriptional pulsing has been observed in both prokaryotes and eukaryotes and plays a crucial role in cell-to-cell variability of protein and mRNA numbers. An important issue is how the time constants associated with episodes of transcriptional bursting and mRNA and protein degradation rates lead to different cellular mRNA and protein distributions, starting from the transient regime leading to the steady state. We address this by deriving and then investigating the exact time-dependent solution of the master equation for a transcriptional pulsing model of mRNA distributions. We find a plethora of results. We show that, among others, bimodal and long-tailed (power-law) distributions occur in the steady state as the rate constants are varied over biologically significant time scales. Since steady state may not be reached experimentally we present results for the time evolution of the distributions. Because cellular behavior is determined by proteins, we also investigate the effect of the different mRNA distributions on the corresponding protein distributions using numerical simulations

From early intervention in psychosis to youth mental health reform: a review of the evolution and transformation of mental health services for young people.

PURPOSE: The objective of this review is to report on recent developments in youth mental health incorporating all levels of severity of mental disorders encouraged by progress in the field of early intervention in psychotic disorders, research in deficiencies in the current system and social advocacy. METHODS: The authors have briefly reviewed the relevant current state of knowledge, challenges and the service and research response across four countries (Australia, Ireland, the UK and Canada) currently active in the youth mental health field. RESULTS: Here we present information on response to principal challenges associated with improving youth mental services in each country. Australia has developed a model comprised of a distinct front-line youth mental health service (Headspace) to be implemented across the country and initially stimulated by success in early intervention in psychosis; in Ireland, Headstrong has been driven primarily through advocacy and philanthropy resulting in front-line services (Jigsaw) which are being implemented across different jurisdictions; in the UK, a limited regional response has addressed mostly problems with transition from child-adolescent to adult mental health services; and in Canada, a national multi-site research initiative involving transformation of youth mental health services has been launched with public and philanthropic funding, with the expectation that results of this study will inform implementation of a transformed model of service across the country including indigenous peoples. CONCLUSIONS: There is evidence that several countries are now engaged in transformation of youth mental health services and in evaluation of these initiatives.This is the author accepted manuscript. The final version is available from Springer via http://dx.doi.org/10.1007/s00127-015-1165-

Scaling laws governing stochastic growth and division of single bacterial cells

Uncovering the quantitative laws that govern the growth and division of single cells remains a major challenge. Using a unique combination of technologies that yields unprecedented statistical precision, we find that the sizes of individual Caulobacter crescentus cells increase exponentially in time. We also establish that they divide upon reaching a critical multiple ($\approx$1.8) of their initial sizes, rather than an absolute size. We show that when the temperature is varied, the growth and division timescales scale proportionally with each other over the physiological temperature range. Strikingly, the cell-size and division-time distributions can both be rescaled by their mean values such that the condition-specific distributions collapse to universal curves. We account for these observations with a minimal stochastic model that is based on an autocatalytic cycle. It predicts the scalings, as well as specific functional forms for the universal curves. Our experimental and theoretical analysis reveals a simple physical principle governing these complex biological processes: a single temperature-dependent scale of cellular time governs the stochastic dynamics of growth and division in balanced growth conditions.Comment: Text+Supplementar