First inkling of maleness began when parasitic bacteria jumped between cells

Main Category: Infectious Diseases / Bacteria / Viruses
Article Date: 10 May 2004 - 0:00 PDT

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The first inkling of maleness began when parasitic bacteria jumped between cells, dragging their host's genes with them. And according to the researcher who came up with the controversial idea, the vestiges of this inauspicious beginning persist in the sperm of animals today.

Some time between 2000 million and 700 million years ago, bacteria entered into an uneasy truce with larger cells. These cells were the precursors of complex eukaryotic cells, that eventually evolved into today's multicellular animals and plants.

The bacteria wound up losing around 90 per cent of their genes to the host nucleus and became mitochondria - the energy-generating components of complex cells. But modern mitochondria are so intimately involved in sexual reproduction that one scientist thinks they may even have been responsible for the evolution of sex itself.

Chris Bazinet, at St John's University in New York believes that early mitochondria were mischievous. They could have colonised new hosts by bursting out and jumping to nearby cells.

Paradoxically, this might have benefited the host cell if the mitochondria took genes from the nucleus with them. Sharing genes can be a big plus because it allows a cell to adapt to new environments or threats.

This in turn could have led to the process of gene donation and acceptance becoming formalised and controlled by the host's genome. "Donators" were proto-males and "acceptors" proto-females (Bioessays, vol 26, p 558).

The News Scientist

Full article: http://www.newscientist.com/news/news.jsp?id=ns99994960

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