Cell biology of synaptic plasticity

The nervous system of mammals retains throughout the animals' life-span the ability to modify the number, nature, and level of activity of its synapses. Synaptic plasticity is most evident after injury to the nervous system, and the cellular and molecular mechanisms that make it possible are beginning to be understood. Transplantation of brain tissue provides a powerful approach for studying mechanisms of synaptic plasticity. In turn, understanding the response of the central nervous system to injury can be used to optimize transplant survival and integration with the host brain.     

Cell biology. Bacterial spelunkers

Bacteria that are engulfed by phagocytic cells of the immune system are usually destroyed once inside the host cell but not always. Why is it that sometimes engulfed bacteria survive and thrive quite happily inside the host cell? As Mulvey and Hultgren explain in their Perspective, the answer may lie in small indentations in the host cell plasma membrane called caveolae that direct certain signal transduction pathways inside the host cell (Shin et al.). If bacteria adhere to regions of the host cell surface that is rich in caveolae, they are better able to survive once inside the cell.     

Cell biology. Stem cell scorecard

As researchers continue to explore the potential uses of stem cells obtained from a variety of sources (see main text), governments around the world are grappling with whether to allow research on stem cells derived from human embryos. Governments are cautious yet increasingly open to the new research, which may eventually yield treatments for a variety of diseases from Parkinson's to diabetes.