NANOTECHNOLOGY: Magnetic Switch Flips On Immune Cell
In the January Nature Nanotechnology, Donald Ingber (front) and colleagues, including (clockwise from left) Flavia Cassiola, Martin Montoya-Zavala, and Robert Mannix, report that they have created a nanomagnetic cellular switch that can rapidly and reliably activate mast cells, part of the immune system. Like many cells, these are not activated one receptor at a time, but instead by the activation of clusters of receptors. The researchers mimicked this receptor clustering by attaching a single tiny iron oxide bead to each mast cell receptor and exposing the cells to a magnetic field. Once exposed, the beads became magnetized, attracting one another and, at the same time, pulling the receptors into scaffoldlike clusters, leading to cell activation.

ONCOLOGY: Targeting Tumor Stem Cells Halts Melanoma
In findings that advance the relatively new cancer stem cell hypothesis, researchers have identified a small subset of melanoma cells that fuel the spread of the deadly skin cancer. More significantly, the team successfully halted cancer growth in mice by killing only these cells. The study, by  researchers including (clockwise from bottom left) Markus Frank, Tobias Schatton, George Murphy, and Natasha Frank, appears in the Jan. 17 Nature.

GENETICS: Broad Reliance on Host Could Prove Deadly for HIV
HIV contains just nine genes encoding 15 proteins. Lacking robust machinery, the virus has to hijack human proteins to propagate, and these might represent powerful therapeutic targets. Using RNA interference to screen thousands of genes, a team led by Stephen Elledge has now identified 273 human proteins utilized by HIV; the vast majority had not been connected to the virus by previous studies. The paper, which appeared online in Science on Jan. 10, implicated proteins involved in cellular pathways ranging from autophagy to retrograde trafficking from the Golgi.

Copyright 2007 by the President and Fellows of Harvard College