Fatal Fold in Protein

This fits with the work of surgeon Jeffrey Macklis at the Harvard Medical School, who in collaboration with Lindquist and others, found the prion, as a normal PrP protein, is abundant and apparently useful, especially in brain tissue. It is also widespread in nature. CPEB acts much the same and can transmit inherited information in yeast, without needing genetic material, meaning DNA or RNA. Also, from work in mice, it is now clear that the normal, non-distorted PrP protein must be present so the brain can build new nerve cells, supporting the growth of neurons needed for proper brain development.

‘‘It’s intriguing to find that PrP, which, when misfolded, subjects people and animals to these ravaging diseases, is so abundant in our brains,’’ Macklis told the Harvard Gazette. Its function is being uncovered by Lindquist, Macklis, Kandel and colleagues, leading toward an understanding of what’s normal and abnormal. ‘‘What’s really exciting is that a protein in the brains of higher animals undergoes a prion switch similar to what we see in yeast,’’ Lindquist added. And once it has switched, ‘‘we believe it is in the prion state, which is when it’s active and maintaining connections’’ between neurons. ‘‘It’s a system for passing along information. So we think it’s a not-so-bizarre mechanism.’’

What is bizarre is the set of diseases caused by bad-acting prions. Disease begins when a small, misfolded PrP molecule meets a normal version of the same molecule, causing the normal to snap into abnormal form, a prion. Each prion then goes on to do the same, touching off a chain reaction that begins filling the brain with gobs of a dense protein, amyloid. Brain function is destroyed. Fatal, but rare, diseases that result are called scrapie in sheep, and Creutzfeldt-Jakob disease and kuru in humans. The cow version—called ‘‘mad cow disease’’—apparently got into more than 100 humans in England who ate prion-contaminated beef.

Prion is a word coined by biologist Stanley Prusiner at the University of California in San Francisco. He won a Nobel Prize in 1997 for his discovery that prions are not normal living organisms: they have no genes of their own, don’t follow normal infection patterns but must be passed from body to body in contaminated meat, or sometimes on surgical tools that cannot be sterilised, even at high temperatures. (Robert Cooke)

Dirty is clean

As any car owner knows, automobiles sometimes attract aquatic insects, like mayflies. The insects mistake the shiny car surface for water and try to lay their eggs on it. In The Proceedings of The Royal Society B, published online, Gyorgy Kriska and three other Hungarian scientists ask what is the environmentally friendly colour of cars? Using shiny plastic sheets in different colours, the researchers tested previous observations that insects are attracted to red and to dark colors. The insects much preferred the red and the black, and the reason, the authors say, is that the light reflected from the dark surfaces is highly polarised and reflected in a horizontal direction—just like water. Light from the yellow and the white cars was less polarized and less horizontally reflected. The authors recommend light-colored cars for visitors to wetland habitats. But even better, they say, are dirty cars, which don’t fool the insects at all. ‘‘Thus,’’ the authors conclude, ‘‘the most environmentally friendly car would be one that never gets washed.’’ It would save on water, too.