Stress, order and survival
[From: D. Frenkiel-Krispin, S. Levin-Zaidman, E. Shimoni, S. G. Wolf, E. J. Wachtel, T. Arad, S. E. Finkel, R. Kolter and A. Minsky,
"Regulated Phase Transitions of Bacterial Chromatin: a Non-Enzymatic Pathway for Generic DNA Protection",
EMBO Journal 20, 1184 (2001).]
Molecular order in its utmost manifestation, the crystalline or liquid-crystalline states, is considered to be incompatible with life.Yet, in living systems exposed to severe environmental conditions such as extreme starvation, the sequestration of vital macromolecules imparted by ordered intracellular assemblies may confer an efficient means for wide range protection.
The figure depicts a transmission electron micrograph of a starved bacterial cell, whose DNA is organized as a liquid-crystal (yellow, at the center of the cell), and is completely separated from the ribosomes that are localized at the periphery. The reorganization of the DNA into a tightly-packed liquid-crystalline phase provides a reversible, highly effective non-enzymatic mode of generic DNA protection.
The background represents a spontaneously obtained liquid crystalline phase of isolated bacterial DNA, as observed by polarized light microscopy.
