Theoretically

"Like assembling a snowflake in a blast furnace" was how one scientist at the Fermi National Accelerator in Batavia, Illinois, described the process of making antimatter here on Earth. But the Fermilab last week made seven atoms of antihydrogen - a positron and an antiproton. That was first achieved in January by Europe's CERN, but the Fermilab hopes to go into mass production of antimatter.

Aspirin's wonder drug status has been further enhanced: it protects against nerve cell death. A team in Italy has reported in Science how giving it to rats, in the concentrations used to treat chronic muscle and joint inflammation, also prevents the neurotransmitter glutamate from killing neurons. That's on top of aspirin's ability to lessen the risk of strokes and heart attacks when taken over the long term. It's cheap, too.

Gene hunters are closing in on two more diseases. Millennium Pharmaceuticals of Cambridge, Massachusettsidentified a gene that leads to type II diabetes, which makes up about 90 per cent of cases. Meanwhile a team at the National Center for Human Genome Research in Bethesda, Maryland, narrowed the search for a gene mutation implicated in 3 per cent of prostate cancers to part of chromosome 1. They now intend to pin down the exact location for the gene, which causes about one-third of hereditary prostate cancers.

Maize really is strange stuff, say a team who have studied its genome and found it to be full of genetic additions that could weaken, kill or drastically alter the plant's cells - but don't. The extra material resembles retroviruses - which insert their genetic material into that of the host (HIV is a well-known example). Some may be fragments of infectious retroviruses picked up in the plant's evolution. Maize somehow stops damage from the extra genetic material by keeping it away from active genes. The data could give genetic engineers a better blueprint to change maize plants, and perhaps help to develop more efficient techniques for human gene therapy.

Fish that change sex - yes, again. A British report two weeks ago said it was all the fault of natural oestrogen rather than chemicals from the Pill. Dutch scientists now say that chemicals in the environment are causing the trouble. Sylvia Gimeno and colleagues in Delft told Nature that they exposed young carp to TPP, a common industrial chemical. In common with another group of fish exposed to oestrogen, male fish developed an oviduct, which female fish use to lay eggs. The team suggested using their test to check the effects of other chemicals in the environment. What the fish think isn't clear.