On the radar

The pick of the science news

Heavy as a feather

How birds replace their feathers is associated with their size, according to a US study.

Heavyweights, such as swans and pelicans, can tip the scales at 15kg, but even smaller birds of around 3kg have complex patterns of feather loss and replacement to compensate for reduced flight performance while the feathers are growing back, the study finds.

"Larger species either prolong moult over two or more years, adopt complex patterns of multiple feather replacement to minimise gaps in the flight surface, or, among species that do not rely on flight for feeding, simultaneously moult all their flight feathers," write the authors in PloS Biology.

Smuggled in a bug

You might not want it in your food, but toxic bacterium Listeria could smuggle vaccines into humans using pills rather than injections.

Scientists in Australia have engineered a "suicidal" strain of the food-borne pathogen, Listeria monocytogenes, so that it no longer causes disease, but can still enter mammalian cells and burst open, potentially delivering a payload of vaccines.

"[The live bacterium] has the potential to deliver protein vaccines to the oral epithelium, which may make possible an inexpensive method for oral vaccination," write the authors in the Molecular Pharmaceuticsjournal.

By numbers

10,000

The number of signatories on a statement to keep libel laws out of science. UK charity Sense About Science started the campaign when the British Chiropractic Association sued science author Simon Singh for writing that the organisation “happily promotes bogus treatments”.

Quote

“We are concerned about current patterns of serious cases and deaths that are occurring primarily among young persons

– The World Health Organisation, which last week declared a pandemic of influenza A(H1N1), or ‘swine flu’