Regulation of sedimentation rate shapes the evolution of multicellularity in a close unicellular relative of animals.

Significant increases in sedimentation rate accompany the evolution of multicellularity. These increases should lead to rapid changes in ecological distribution, thereby affecting the costs and benefits of multicellularity and its likelihood to evolve. However, how genetic and cellular traits control this process, their likelihood of emergence over evolutionary timescales, and the variation in these traits as multicellularity evolves are still poorly understood.

Harmonious genetic combinations rewire regulatory networks and flip gene essentiality.

We lack an understanding of how the full range of genetic variants that occur in individuals can interact. To address this shortcoming, here we combine diverse mutations between genes in a model regulatory network, the galactose (GAL) switch of budding yeast. The effects of thousands of pairs of mutations fall into a limited number of phenotypic classes.

Transition between fermentation and respiration determines history-dependent behavior in fluctuating carbon sources.

Cells constantly adapt to environmental fluctuations. These physiological changes require time and therefore cause a lag phase during which the cells do not function optimally. Interestingly, past exposure to an environmental condition can shorten the time needed to adapt when the condition re-occurs, even in daughter cells that never directly encountered the initial condition.

Noise and Epigenetic Inheritance of Single-Cell Division Times Influence Population Fitness.

The fitness effect of biological noise remains unclear. For example, even within clonal microbial populations, individual cells grow at different speeds. Although it is known that the individuals' mean growth speed can affect population-level fitness, it is unclear how or whether growth speed heterogeneity itself is subject to natural selection.

Different levels of catabolite repression optimize growth in stable and variable environments.

Organisms respond to environmental changes by adapting the expression of key genes. However, such transcriptional reprogramming requires time and energy, and may also leave the organism ill-adapted when the original environment returns. Here, we study the dynamics of transcriptional reprogramming and fitness in the model eukaryote Saccharomyces cerevisiae in response to changing carbon environments.

A novel regulatory protein involved in motility of Vibrio cholerae.

The facultative pathogen Vibrio cholerae is the causative agent of the human intestinal disease cholera. Both motility and chemotaxis of V. cholerae have been shown to contribute to the virulence and spread of cholera.

Ribosomal features essential for tna operon induction: tryptophan binding at the peptidyl transferase center.

Features of the amino acid sequence of the TnaC nascent peptide are recognized by the translating ribosome. Recognition leads to tryptophan binding within the translating ribosome, inhibiting the termination of tnaC translation and preventing Rho-dependent transcription termination in the tna operon leader region. It was previously shown that inserting an adenine residue at position 751 or introducing the U2609C change in 23S rRNA or introducing the K90W replacement in ribosomal protein L22 prevented tryptophan induction of tna operon expression.