A Phosphorylation Switch on Lon Protease Regulates Bacterial Type III Secretion System in Host.

Most pathogenic bacteria deliver virulence factors into host cytosol through type III secretion systems (T3SS) to perturb host immune responses. The expression of T3SS is often repressed in rich medium but is specifically induced in the host environment. The molecular mechanisms underlying host-specific induction of T3SS expression is not completely understood.

Scaling, selection, and evolutionary dynamics of the mitotic spindle.

Background: Cellular structures such as the nucleus, Golgi, centrioles, and spindle show remarkable diversity between species, but the mechanisms that produce these variations in cell biology are not known.

Results: Here we investigate the mechanisms that contribute to variations in morphology and dynamics of the mitotic spindle, which orchestrates chromosome segregation in all Eukaryotes and positions the division plane in many organisms. We use high-throughput imaging of the first division in nematodes to demonstrate that the measured effects of spontaneous mutations, combined with stabilizing selection on cell size, are sufficient to quantitatively explain both the levels of within-species variation in the spindle and its diversity over ∼100 million years of evolution.

Who needs stem cells if you can dedifferentiate?

Regenerative mechanisms involving either stem cell differentiation or dedifferentiation of mature cells have been described in various systems, but the relationship between such disparate mechanisms is unclear. Two recent papers, one by Sandoval-Guzmán et al. (2013) and one by Tata et al.