Modified mouse cells make proteins that include synthetic amino acids in addition to the 20 natural ones. (p. 30)

A gene that's active in the brain may help explain why emotional stress seems to increase a person's likelihood of getting Alzheimer's disease. (p. 13)

The life-extending effect that some animals get from calorie-restricted diets may depend on signals from the brain. (p. 414)

Artificial genes inserted into cells make RNA molecules that can perform logical computations. (p. 413)

With the help of a molecule from the rabies virus, scientists have for the first time selectively ferried a drug across the blood-brain barrier to treat a neurological disease in mice. (p. 387)

Microscopic, fluorine-packed particles can make small, cancerous growths easier to detect. (p. 398)

RNA snippets of a newly discovered type could be involved in the mechanisms of cancer. (p. 398)

A mutated gene that's overly active in breast cancer cells could offer a new target for cancer drugs. (p. 371)

Insulin-producing cells in the pancreas proliferate by cell division, unlike other body tissues, which regenerate from adult stem cells. (p. 350)

Radiation and chemotherapy can destroy a tumor, but they may also indirectly promote metastasis, the spread of cancerous cells to other organs. (p. 334)

Researchers have discovered a new way that so-called junk DNA could help regulate gene activity. (p. 309)

Scientists have found a master gene that allows tissue-regenerating stem cells to retain their regenerative capacity. (p. 292)