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How does a Killer T Cell Kill its target? Our new film captures the behaviour of cytotoxic T cells - the body's 'serial killers' - as they hunt down and eliminate cancer cells before moving on to their next target.

The worst cancer cells don't sit still. Instead they metastasize-migrate from their original sites and establish new tumors in other parts of the body. Once a cancer spreads, it is harder to eliminate. A study by developmental biologists offers a fresh clue to how cancer cells acquire the ability to invade other tissues-a prerequisite for metastasis. It reveals that invasion requires cells to stop dividing. Therefore, the two processes- invasion and proliferation-are mutually exclusive. The finding could inform cancer therapies, which typically target rapidly proliferating cancer cells.

HIV is a disease of the gut, a concept that's easy to lose sight of with all the attention paid to sexual transmission and blood measurements of the virus and the CD4+ T cells it infects and kills. But the bottom line is that about two thirds of all T cells reside in the lymphoid tissue of the gut, where the virus spreads after exposure, even before it shows up in blood.

Immune cell maturation details

An overview of the immune system, concentrating on the roles played by B and T lymphocytes, and the antigen-presentation system.

CRISPR still has a long way to go before it can be used safely and effectively to repair-not just disrupt-genes in people. That is particularly true for most diseases, such as muscular dystrophy and cystic fibrosis, which require correcting genes in a living person because if the cells were first removed and repaired then put back, too few would survive. And the need to treat cells inside the body means gene editing faces many of the same delivery challenges as gene transfer-researchers must devise efficient ways to get a working CRISPR into specific tissues in a person, for example. CRISPR also poses its own safety risks. Most often mentioned is that the Cas9 enzyme that CRISPR uses to cleave DNA at a specific location could also make cuts where it's not intended to, potentially causing cancer.

Every second of your life you are under attack. Bacteria, viruses, spores and more living stuff wants to enter your body and use its resources for itself. The immune system is a powerful army of cells that fights like a T-Rex on speed and sacrifices itself for your survival. Without it you would die in no time. This sounds simple but the reality is complex, beautiful and just awesome. An animation of the immune system.

We see color because of specialized light-sensing cells in our eyes called cones. One type, L-cones, sees the reds of strawberries and fire trucks; M-cones detect green leaves, and S-cones let us know the sky is blue. But vision scientists have now discovered that not all cones sense color (see video).