Designer yeast brings key to creation a step closer

Scientists have created the first man-made chromosome for a complex-celled organism - a feat hailed as a big step towards acquiring the ability to redesign plants and animals.

A synthetic chromosome was inserted into a yeast cell and the cell functioned normally - the key test of success, a research team reported in the journal Science.

"Our research moves the needle in synthetic biology from theory to reality," said Jef Boeke, director of New York University's Institute for Systems Genetics.

Yeast is a eukaryote, an organism with cells that contain a nucleus and other structures enclosed in a membrane.

All plants and animals, including humans, have eukaryotic cells.

Chromosomes have previously been synthesised for bacteria, which are simpler organisms.

Boeke and his team unravelled the coding of one of yeast's 16 chromosomes, then used computer software to design changes to it, removing repetitive and less-used regions.

They then built a synthetic version of this altered chromosome from scratch, stringing together nucleotides - the chemical building blocks of the genes that make up chromosomes, which in turn comprise the genome.

"We have made over 50000 changes to the DNA code and our yeast is still alive. That is remarkable," said Boeke.

Yeast shares about a third of its 6000 genes with humans.