September 2, 2005

GENOMICS
Molecular Networks Uncovered in Bacterial Infection, Nerve Cell Communication
Using RNA interference (RNAi), researchers across HMS and, indeed, around the world are conducting global analyses of genes and the molecules they produce to build an understanding of functional networks within cells. Darren Higgins (left), Norbert Perrimon (right), and their colleagues teamed up for a genomewide RNAi study to see how two different species of bacteria enter and get a foothold inside Drosophila cells. Their findings, which include a long-sought receptor gene, appeared in a pair of papers on July 14 in Science Express. Similarly, Joshua Kaplan and his collaborators report in the July 28 Nature the first large-scale RNAi screen in neurons, revealing nearly 200 genes involved in transmission of signals across the synapse.

MICROBIOLOGY: Critical Step Traced in Anthrax Infection
A recent study, which grew out of the ongoing effort to produce a better anthrax therapeutic, shows that one component of the three-part anthrax toxin plays an active role in transferring the other two across the cell membrane. This active component, protective antigen, forms a pore in the membrane, whose specific pore-forming domain has a clamplike structure that may aid in unfolding the other two components during their translocation into the cell. The study, led by R. John Collier and published in the July 29 Science, gives insight into the broader question of how proteins cross cell membranes.

HEALTH CARE POLICY: Some Care Disparities Narrow
Though Inequalities Persist
More focused programs will be needed to eliminate persistent racial disparities in health care, concluded the authors of three large studies in the Aug. 18 New England Journal of Medicine, even though one of the studies found some improvements in the last decade. Better care for all seniors in managed-care Medicare plans helped narrow the racial gap for seven out of nine measures of quality, according to a study led by Amal Trivedi (left). But research led by Ashish Jha (right) found no consistent reduction in racial differences in the rates of nine major surgical procedures on blacks and whites enrolled in the larger fee-for-service Medicare.

PATHOLOGY: Protein Links Dopamine and Depression
The neurotransmitter dopamine is responsible for carrying out subtle functions such as motor control, motivation, response to reward, and mood—but how this single message is translated into such different actions is unclear. A study from the laboratory of Li-Huei Tsai, published in the July 29 Cell, uncovers a molecule that helps regulate how neurons respond to dopamine. The molecule, Par-4, also provides a surprising connection between dopamine communication and depression in an animal model.