Science: Lab Notes

Attack of the fire ants

Fire ants, named for their burning stings, have long been a pest in the southern US, destroying crops, displacing other insects and terrorising people and small mammals. These aggressive insects have also invaded the Galapagos Islands and parts of the South Pacific. Now scientists fear that one species of the ant, Wasmannia auropunctata, may be wreaking havoc in West Africa and possibly blinding elephants.

Wasmannia is a distant relative of Solenopsis wagneri, the species that plagues the US. Once en- trenched, fire ants are extremely difficult to dislodge. In the US, insecticides such as Dieldrin (far more toxic than DDT) have failed to eradicate it.

Although the ecological ramifications of the migration are not known, early indications have been frightening. In the Pacific, observers say that fire ants have eaten the hatchlings of tortoises and attacked the eyes of adult dogs. In Gabon, villagers report elephants with cloudy eyes behaving as if blind, and ecologists warn that irreversible damage may be occurring.

Thoughtful gestures

People who have been blind from birth gesture with their hands just as much as the sighted do, even though they cannot see how those gestures help others to understand them. Jana Iverson of Indiana University and Susan Meadow of the University of Chicago found that when speaking, individuals born blind make just as many hand motions in virtually the same ways as sighted person - even when talking to other blind people. This finding suggests that hand movements may only partially serve the function of emphasising words: they may also assist with the storage and recall of words. Iverson also found that sighted adults could recall cartoons better if they moved their hands while describing them.

Natural cancer immunity

Researchers from Rockefeller University in New York have demonstrated for the first time that people can develop immunity to tumours. The study provides support for the development of immunotherapies - a treatment in which clinicians attempt to activate immune response - for cancer patients.

This evidence has emerged from studies of a rare, debilitating neurological disease called paraneoplastic cerebellar disorder (PCD), often associated with certain breast and ovarian cancers, which causes neurological abnormalities such as severely disrupted co-ordination.

Rockefeller scientists found that the tumours in four PCD patients were kept in check as their immune systems targeted a protein called cdr2 produced by the tumours. Cdr2 is an antigen that is usually expressed only in the part of the brain called the cerebellum. As the immune system fights to slow the cancer's growth, it incidentally attacks and destroys the brain cells that carry the same target protein. The researchers found killer T cells specific to the cdr2 antigen in the blood of their PCD patients, an important finding because tumour-specific killer T cells have not previously been found in humans in large numbers.

All items are adapted from 'Scientific American' magazine. Visit the website at www.sciam.com