Apico-basal polarity is a hallmark of epithelial tissues. The integrated activity of several evolutionarily conserved protein complexes is essential to control epithelial polarity during development and homeostasis. Many components of these protein complexes were originally identified in genetic screens performed in Drosophila or Caenorhabditis elegans due to defects in cell polarity. With time...

The "immortal strand" hypothesis proposes that asymmetrically dividing stem cells selectively retain chromosomes containing "old" DNA to prevent accumulation of mutations. As I describe in this Essay, such a possibility seems unlikely. An alternative explanation is that asymmetric cell divisions and cell fate are codirected by epigenetic differences between sister chromatids.

Stomata are epidermal structures that are responsible for modulating the exchange of gases between the plant and the environment. Stomata are formed and patterned by asymmetric cell divisions. The number and orientation of these asymmetric divisions is informed by plant intrinsic signals acting locally (among epidermal cells) or at a distance (from mature to young leaves) and by plant extrinsic...

Stem cells can self-renew and generate differentiating daughter cells. It is not known whether these cells maintain their epigenetic information during asymmetric division. Using a dual-color method to differentially label "old" versus "new" histones in Drosophila male germline stem cells (GSCs), we show that preexisting canonical H3, but not variant H3.3, histones are selectively segregated to...

Three recent studies show that centrosome asymmetry correlates with self-renewal of Drosophila neural and germline stem cells and that equalizing centrosomes disrupts asymmetric cell division.

Asymmetric distribution of fate determinants within cells is an essential biological strategy to prepare them for asymmetric division. In this work we measure the intracellular distribution of 12 maternal microRNAs (miRNA) along the animal-vegetal axis of the Xenopus laevis oocyte using qPCR tomography. We find the miRNAs have distinct intracellular profiles that resemble two out of the three p...

Heterogeneity within a clonal population of cells can increase survival in the face of environmental stress. In a recent issue of Science, Aldridge et al. (2012) demonstrate that cell division in mycobacteria is asymmetric, producing daughter cells that differ in size, growth rate, and susceptibility to antibiotics.

Towards a single-molecule study of asymmetric cell division

Asymmetric cell division plays a major role in the generation of cell diversity during development. In this issue of Neuron, Sun and colleagues present evidence that the epidermal growth factor receptor is asymmetrically distributed in mitotic cerebral cortical precursors, and the resulting unequal inheritance generates offspring with different responsiveness to growth factor and unique cell fa...