Ratiometric sensing of Pnt and Yan transcription factor levels confers ultrasensitivity to photoreceptor fate transitions in Drosophila.

Cell state transitions are often triggered by large changes in the concentrations of transcription factors and therefore large differences in their stoichiometric ratios. Whether cells can elicit transitions using modest changes in the ratios of co-expressed factors is unclear. Here, we investigate how cells in the Drosophila eye resolve state transitions by quantifying the expression dynamics of the ETS transcription factors Pnt and Yan.

The Wg and Dpp morphogens regulate gene expression by modulating the frequency of transcriptional bursts.

Morphogen signaling contributes to the patterned spatiotemporal expression of genes during development. One mode of regulation of signaling-responsive genes is at the level of transcription. Single-cell quantitative studies of transcription have revealed that transcription occurs intermittently, in bursts.

Repressive Gene Regulation Synchronizes Development with Cellular Metabolism.

Metabolic conditions affect the developmental tempo of animals. Developmental gene regulatory networks (GRNs) must therefore synchronize their dynamics with a variable timescale. We find that layered repression of genes couples GRN output with variable metabolism.

MicroRNAs Make a Difference in Cardiovascular Robustness.

Invertebrate microRNAs (miRNAs) can suppress developmental variability that is caused by environmental and genetic variation. In this issue of Developmental Cell, Kasper et al. (2017) show that zebrafish miRNAs suppress variability in cardiovascular development during embryogenesis, providing insight into the conserved link between miRNAs and robustness.

Functional analysis of the Arabidopsis thaliana MUTE promoter reveals a regulatory region sufficient for stomatal-lineage expression.

The MUTE promoter contains a 175-bp region rich in Dof regulatory elements (AAAG) that is necessary and sufficient for initiation of transcription in meristemoids and the stomatal lineage. The molecular mechanism underlying the decision to divide or differentiate is a central question in developmental biology. During stomatal development, expression of the master regulator MUTE triggers the differentiation of meristemoids into stomata.