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The size of cells fluctuates but there are limited experimental methods to measure live mammalian cell sizes. Here, the authors track single cell volume (FXm) over the cell cycle and generate a mathematical framework to compare size homeostasis in datasets ranging from bacteria to mammalian cells.

To maintain homeostasis in epithelial cell layers in Drosophila, cell overcrowding causes a proportion of cells to undergo a loss of cell adhesive junctions and be squeezed out by neighbouring cells.

A study of division in proliferating animal cells points to the existence of a kinetochore-based signalling pathway, independent of furrow formation, centrosomes and microtubules, that couples chromosome segregation to cell division.

In a study performed in Schizosaccharomyces pombe, ‘closed mitosis’ is shown to occur via local disassembly of the nuclear envelope within the narrow bridge connecting segregating daughter nuclei, and a key role is identified for Les1, which restricts nuclear envelope breakdown to the bridge.

DPANN archaea are a group of microorganisms that require direct cell contact with other archaeal host species for growth. Here, Hamm et al. show that a DPANN archaeon engages in parasitic interactions with its host leading to host cell lysis, thus providing experimental evidence of a predatory-like lifestyle for an archaeon.

Filaments of keratin — stable protein polymers best known for their function in hair and nails — provide a memory of cell polarity at a crucial stage in early mouse development.

Epithelial tissues behave as pre-tensed viscoelastic sheets that can buffer against compression and rapidly recover from buckling. Epithelial mechanical properties define a tissue-intrinsic buckling threshold that dictates the compressive strain above which tissue folds become permanent.

Highlights the benefits to be gained by panning the older literature for new ideas and methods.

Stress relaxation in cell monolayers shows remarkable similarities with that of single cells, suggesting the rheology of epithelial tissues is mediated by the actomyosin cortex—with dynamics reminiscent of those on a cellular level.

The ESCRT pathway is crucial for membrane remodelling in eukaryotes. Here, Hatano et al. explore the phylogeny, structure, and biochemistry of homologues of the ESCRT machinery and the associated ubiquitylation system in Asgard archaea, the closest living relatives of eukaryotes.

Sample processing for biological imaging experiments involves elaborate protocols with low reproducibility and throughput. Here the authors develop an open-source system called NanoJ-Fluidics, composed of off-the-shelf Lego components and an ImageJ-based controller to achieve automated fixation, labelling and imaging of cells.

Cowman and colleagues present their analysis of the repertoire of actin-binding proteins and actin-regulatory proteins in apicomplexan parasites. They integrate their observations with recent progress in understanding actin, actin-binding proteins and actin-regulatory proteins to propose a modified model of apicomplexan gliding motility, in which actin dynamics have a central role.

Both symmetric and asymmetric divisions rely on alignment of the mitotic spindle with cues from the environment. A study now shows that mitotic spindles find their position by reading the map of forces that load-bearing retraction fibres exert on the cell body.

When animal cells divide, they undergo dramatic changes in shape, polarity and mechanical properties. At mitotic entry, the remodelling of cortical actomyosin and cell–substrate adhesions, combined with osmotic swelling enable cell rounding, which is then reversed as cells exit mitosis. We now have a better understanding of the regulation of such shape changes and how they contribute to accurate segregation of chromosomes and other cellular components.

Large-scale RNA interference (RNAi)-based analyses, very much as other 'omic' approaches, have inherent rates of false positives and negatives. The variability in the standards of care applied to validate results from these studies, if left unchecked, could eventually begin to undermine the credibility of RNAi as a powerful functional approach. This Commentary is an invitation to an open discussion started among various users of RNAi to set forth accepted standards that would insure the quality and accuracy of information in the large datasets coming out of genome-scale screens. Please visit methagora to view and post comments on this article

RT-FDC combines the specificity of fluorescent probes with functional readout of a cell's mechanical properties. The resulting correlation of fluorescence-based cell identity with mechanical measurements in real time allows the development of label-free, mechanical cell sorting.

The authors review archaeal morphology, surface features, internal organization and cell division, discussing the state of the art and future research directions.