evolution
Learn to live with it
A species of tropical butterfly evolved quickly in the last century. It was facing extinction. The butterfly Hypolimnas bolina is susceptible to the bacterium Wolbachia that only kills the male butterflies and skews the male-to-female ratio. The team compared genetic material from museum specimens with that from the living butterflies. They found that in some butterfly populations, a gene had evolved that suppresses the effects of the bacterium so that infected males can survive. The group is now trying to understand how the gene works (Current Biology, September 10).
biology
Head for tails
Geckos drop their tails during fights and the severed tail shows a complex movement-four to eight rhythmic moves along with a couple of flips. This distracts the opponent, giving the gecko time to escape. Researchers suggested that the nerves in the severed tail can function without being linked to a brain or central nervous system. The process provides information which could be used to find cures for people suffering from spinal injuries (Biology Letters, September 9).
health sciences
Don't breathe yet
Exposure to diesel exhaust for a couple of hours a day is enough to give birth to blood vessels that feed tumours. Experiments on mice showed that exposure to diesel exhaust caused a six-fold increase in blood vessel formation in diseased mice and a four-fold increase in healthy mice breathing diesel fumes. There was no such increase in mice breathing filtered air. The exhaust activated a chemical signal and a protein associated with new blood vessel development. It lowered the activity of an enzyme that can suppress tumour growth (Toxicology Letters, online August 14).
physical sciences
Little cell revolution
| A carbon nanotube-based photo cell | |
| Photograph by NATHAN GABOR |