Model-Based Deconvolution of Cell Cycle Time-Series Data Reveals Gene Expression Details at High Resolution

In both prokaryotic and eukaryotic cells, gene expression is regulated across the cell cycle to ensure “just-in-time” assembly of select cellular structures and molecular machines. However, present in all time-series gene expression measurements is variability that arises from both systematic error in the cell synchrony process and variance in the timing of cell division at the level of the single cell. Thus, gene or protein expression data collected from a population of synchronized cells is an inaccurate measure of what occurs in the average single-cell across a cell cycle. Here, we present a general computational method to extract “single-cell”-like information from population-level time-series expression data. This method removes the effects of 1) variance in growth rate and 2) variance in the physiological and developmental state of the cell. Moreover, this method represents an advance in the deconvolution of molecular expression data in its flexibility, minimal assumptions, and the use of a cross-validation analysis to determine the appropriate level of regularization. Applying our deconvolution algorithm to cell cycle gene expression data from the dimorphic bacterium Caulobacter crescentus, we recovered critical features of cell cycle regulation in essential genes, including ctrA and ftsZ, that were obscured in population-based measurements. In doing so, we highlight the problem with using population data alone to decipher cellular regulatory mechanisms and demonstrate how our deconvolution algorithm can be applied to produce a more realistic picture of temporal regulation in a cell

Quality management systems as a link between management and employees

This paper analyses interactions between two parties (management and employees) with regard to the question of how to successfully manage and implement a quality management system (QMS). It also introduces practical possibilities for improving the employees\u27 understanding of why a QMS must be applied and how management should behave to make it possible. The paper also introduces a role of a third party (a quality representative) who must carefully choose his actions and must, above all else, be aware of the importance of open communication channels among the first two parties. Data were obtained from a research study using a survey among employees of a Slovenian information and communication technology company over a 2-year period. We found that communication between employees and management has significant importance on employee satisfaction. Therefore, communication is the essential element of successful and continuous improvement of the quality management system, in which management must be the first to show the awareness of the real purpose of the QMS, and must attract their employees\u27 attention as well as acknowledge their expectations. However, it should be noted that this factor can be stronger in a high technology company with a higher level of employee education. Conclusions are offered to improve the relationship among all parties through an improved status of the quality representative position over employees, his formal direct access to the management and the right to exercise and manage internal auditing of the system. Nevertheless, informally his role is far greater and consists once again of the crucial element of successfully and continuously improving of the QMS: communication