Modelling radiation-induced cell cycle delays

Ionizing radiation is known to delay the cell cycle progression. In particular after particle exposure significant delays have been observed and it has been shown that the extent of delay affects the expression of damage such as chromosome aberrations. Thus, to predict how cells respond to ionizing radiation and to derive reliable estimates of radiation risks, information about radiation-induced cell cycle perturbations is required. In the present study we describe and apply a method for retrieval of information about the time-course of all cell cycle phases from experimental data on the mitotic index only. We study the progression of mammalian cells through the cell cycle after exposure. The analysis reveals a prolonged block of damaged cells in the G2 phase. Furthermore, by performing an error analysis on simulated data valuable information for the design of experimental studies has been obtained. The analysis showed that the number of cells analyzed in an experimental sample should be at least 100 to obtain a relative error less than 20%.Comment: 19 pages, 11 figures, accepted for publication in Radiation and Environmental Biophysic

Genetic interaction mapping informs integrative structure determination of protein complexes

Determining structures of protein complexes is crucial for understanding cellular functions. Here, we describe an integrative structure determination approach that relies on in vivo measurements of genetic interactions. We construct phenotypic profiles for point mutations crossed against gene deletions or exposed to environmental perturbations, followed by converting similarities between two profiles into an upper bound on the distance between the mutated residues. We determine the structure of the yeast histone H3-H4 complex based on similar to 500,000 genetic interactions of 350 mutants. We then apply the method to subunits Rpb1-Rpb2 of yeast RNA polymerase II and subunits RpoB-RpoC of bacterial RNA polymerase. The accuracy is comparable to that based on chemical cross-links; using restraints from both genetic interactions and cross-links further improves model accuracy and precision. The approach provides an efficient means to augment integrative structure determination with in vivo observations

DEAR1 Is a Dominant Regulator of Acinar Morphogenesis and an Independent Predictor of Local Recurrence-Free Survival in Early-Onset Breast Cancer

Ann Killary and colleagues describe a new gene that is genetically altered in breast tumors, and that may provide a new breast cancer prognostic marker

Volatility and price change spillover effects across the developed and emerging markets

This paper tests the conventional wisdom that short-term volatility and price changes spill over from developed to emerging markets, but not vice versa. We also investigate how degree of market openness affects return and volatility spillovers. Three developed markets, New York, Tokyo, and London, and two emerging markets, Taiwan and Hong Kong, are examined. Two most interesting findings are: first, the Tokyo market has less influence than the New York market over the Taiwanese and Hong Kong markets; and second, the Taiwanese market is more sensitive than the Hong Kong market to the price and volatility behavior of the advanced markets even though Taiwan is not as open as Hong Kong and the Taiwanese dollar is not linked to the U.S. dollar while the Hong Kong dollar is. © 1995

Characteristics of aerosol pollution in the vicinity of an oil refinery near Rijeka, Croatia

Fine aerosol pollution is one of the most important factors in air pollution monitoring. Industrial production often represents significant source of aerosol pollution in surrounding areas, and therefore, it is important to understand its impact on air quality. In order to investigate contribution coming from the oil refinery to air pollution, PM2.5 (particulate matter with aerodynamic diameter smaller than 2.5 μm) samples were collected in the vicinity of an oil refinery during the 1‐year period. At the same time, PM2.5 was sampled in the city of Rijeka, Croatia, at the distance that is about 10 km far from the refinery. This site was used for comparison. The sampling was performed with two cyclone samplers on thin polytetrafluoroethylene filters. PM2.5 was sampled for 24 h every other day, simultaneously at both locations. In total, 306 samples were collected. The samples were analysed using X‐ray fluorescence and particle‐ induced X‐ray emission to obtain concentrations of 17 elements from Na to Pb. Additionally, concentrations of black carbon were determined using laser‐integrated plate method. It was found that concentrations of S, V, and Ni, elements characteristic for oil burning, were substantially higher at the refinery sampling site comparing to the reference location. Obtained concentrations were statistically evaluated by performing positive matrix factorization to identify oil refinery as one of the pollution sources in the vicinity of such a facility. The same method was also performed at the urban site where the contribution from oil refinery was not separated from other similar sources