The Pseudomonas aeruginosa Transcriptional Landscape Is Shaped by Environmental Heterogeneity and Genetic Variation

Phenotypic variability among bacteria depends on gene expression in response to different environments, and it also reflects differences in genomic structure. In this study, we analyzed transcriptome sequencing (RNA-seq) profiles of 151 Pseudomonas aeruginosa clinical isolates under standard laboratory conditions and of one P. aeruginosa type strain under 14 different environmental conditions. Our approach allowed dissection of the impact of the genetic background versus environmental cues on P. aeruginosa gene expression profiles and revealed that phenotypic variation was larger in response to changing environments than between genomically different isolates. We demonstrate that mutations within the global regulator LasR affect more than one trait (pleiotropy) and that the interaction between mutations (epistasis) shapes the P. aeruginosa phenotypic plasticity landscape. Because of pleiotropic and epistatic effects, average genotype and phenotype measures appeared to be uncorrelated in P. aeruginosa

Operations Research Methodology Life Cycle Trend Phases as Recorded in Journal Articles

This paper applies life cycle concepts to forecast and explore trends in the publication rates of operations research (OR) methodology journal articles. The confirmatory part of this study seeks to show the accuracy of life cycles to forecast a trend for a single OR methodology. The exploratory part of this study extends the use of life cycle forecasting to a broader collection of OR methodologies. This part of the study entails a collection of keywords for OR methodologies from over 8,000 journal articles. The results show a life cycle can be used to forecast a trend in OR journal article methodology productivity based on keyword listings. This paper also reveals trends in methodology usage for leading OR journals in Europe and the US. The existence and use of life cycle trends in the OR methodology research have ramifications on new directions for research, research funding, and OR text¬book content