December 7 – 9, 2009 in Arlington, VA, USA
The DNA of the domesticated horse shows evolution at work
THE genomes of many mammals have now been completed, including the cow, the dog, the chimpanzee and, of course, the human. This week it was the turn of the horse to have its DNA sequence decoded. With it emerged further evidence of how horses have been close human companions and, like other mammals that share an evolutionary history with man, how they could help the understanding of hereditary diseases. But there was also a surprise: horses have a newly forming part in their genetic make-up which shows the evolutionary process in action in a way that has not been seen before.
A team of researchers led by Claire Wade, then at the Broad Institute, in Cambridge, Massachusetts, collaborated on the project, which is reported in the latest issue of Science. They analysed DNA from a mare called Twilight (pictured above) to reveal a genome that consists of up to 2.7 billion base pairs (the “letters” in which the genetic message is written). This is slightly larger than the genome of a dog, but smaller than that of a human or a cow. They also compared Twilight, a thoroughbred, with members of other horse breeds. …
Carbon nanotubes find an unusual use as fertilisers
MANURE, compost and ash were used as fertilisers for centuries before the 1800s, but people did not understand how they worked until the science of chemistry was developed in the 19th century and it became clear that they supply plants with nitrogen, phosphorus and potassium. Today, something similar may be happening with a different sort of fertiliser altogether. For reasons that are not yet entirely clear, it looks as though exposing seeds to carbon nanotubes before they germinate makes the seedlings that subsequently sprout grow faster and larger.
A carbon nanotube is, as its name suggests, a tiny cylinder of carbon atoms. Such tubes have been proposed for all sorts of fancy uses, particularly in electronics, but they and other nanoparticles (so called because their dimensions are measured in nanometres, or billionths of a metre) have also been objects of concern. The fear is that if they became ubiquitous, they might damage living creatures, people included, by interfering with the way cells work. …