Nature Biotechnology pp 1082 - 1087

Scientists have engineered plants with increased levels of vitamin E, which is deficient in 25% of the US population and is important for prenatal health and a decreased risk of heart disease. Identification of genes from barley, rice and wheat responsible for the synthesis of tocotrienols, members of the vitamin E family, opens the door to boosting the level of this vitamin in food crops. In the September issue of Nature Biotechnology, Edgar Cahoon and colleagues describe the isolation of the HGGT genes, which encode enzymes that play a key role in tocotrienol synthesis. Overexpression of the barley enzyme in the small weed thale cress (Arabidopsis thaliana) enhances total vitamin E content (tocotrienols plus the other major form, tocopherols) ten- to fifteen fold. In corn seed, levels were increased as much as sixfold. The results demonstrate the feasibility of engineering increased vitamin E levels in plants using this enzyme.

Vitamin E is the generic term for any of eight naturally occurring forms of tocotrienols and tocopherols. The synthesis of tocopherols has been well characterized in plants, whereas the pathway that leads to tocotrienols has not been extensively studied. The results of Cahoon and coworkers provide the first evidence for the synthesis of tocotrienols in plants through the HGGT-catalyzed pathway. Although the work represents a breakthrough for boosting levels of certain tocotrienols, which are powerful antioxidants, further work is needed to produce plants containing dietary forms of the vitamin. Finally, manipulation of these genes could also lead to plants that are more resistant to oxidative stresses.

Nature Biotechnology pp 1033 - 1039

Researchers have developed protein arrays that could be used to diagnose autoimmune diseases, such as multiple sclerosis, earlier than is currently possible. The approach, described in the September issue of Nature Biotechnology, could also facilitate more effective therapeutic interventions.

The immune system normally protects against disease, but in the case of autoimmune disease it attacks the body. To profile the autoimmune response during disease, William Robinson and coworkers developed arrays composed of proteins (antigens) that are targets of the autoimmune response in a mouse model of multiple sclerosis. To identify antigens, they incubated blood from mice on the array and then determined which antigens antibodies had latched onto. They discovered that mice with more severe disease had a larger diversity of antibody responses. Based on the antibody reactivity they detected, they designed vaccines to reduce immune response. Mice treated with these vaccines had a better therapeutic outcome.

Nature Biotechnology pp 1069 - 1074

Tic-tac-toe players can now test their wits against a DNA computer. MAYA, an intricate assembly of DNA enzymes, plays tic-tac-toe against human opponents and remains undefeated after more than 100 games. It was developed by Milan Stojanovic and Darko Stefanovic and is described in the September issue of Nature Biotechnology.

MAYA consists of nine wells that are arranged in the 3X3 pattern of tic-tac-toe board and contain various combinations of DNA enzymes. MAYA signals a move by glowing fluorescently in one of the nine wells, whereas the human player indicates a move by adding a short DNA strand to the wells. The DNA strand is keyed to one of the 9 wells but is added to all the wells. MAYA can ‘analyze’ the DNA strand selected by the human player and make its own move by cutting this DNA in the appropriate well, which triggers the fluorescence. Whatever move the human chooses, MAYA is programmed to respond with the optimal counter-move.

MAYA represents the most advanced implementation of biological ‘digital logic circuits’ yet described and the first use of biological molecules to play an interactive game.