Cell stress and ribosome crystallization.

New methods of inducing ribosome crystals in chick embryos are described, and it is shown that a close relationship exists between cell stress and ribosome crystallization. The formation of ribosome crystals in the nucleus and/or in the cytoplasm depends on the type of treatment and on the temperature of incubation, but in all cases the key event that produces crystallizable ribosomes appears to be a damage to the ribosome transport system. This prevents the movement of messenger-free ribosomes towards their destination sites, and accumulates a pool of potentially crystallizable ribosomes in restricted areas of the cell. This mechanism accounts for the fact that ribosome crystallization occurs in chick embryos in the widely different conditions such as those induced by cooling, anoxia, heat-shocks and programmed cell death.