* Astronomy

Earliest forms of life began in Australia

The findings of a team of Australian and British scientists have broken the current record as the Earth's oldest known forms of microbial life.
They have discovered microscopic fossils, about 3.43 billion years old, in the remote Pilbara region of Western Australia, the Age reported
Until the new discovery, the oldest uncontroversial microbial fossils were 3.2 billion years old, as reported last year from South Africa by Emmanuelle Javaux of Belgiums Liege University.
Read more 

Title: The human genome retains relics of its prokaryotic ancestry: human genes of archaebacterial and eubacterial origin exhibit remarkable differences
Authors: David Alvarez-Ponce and James O. McInerney

Eukaryotes are generally thought to stem from a fusion event involving an archaebacterium and a eubacterium. As a result of this event, contemporaneous eukaryotic genomes are chimaeras of genes inherited from both endosymbiotic partners. These two coexisting gene repertoires have been shown to differ in a number of ways in yeast. Here we combine genomic and functional data in order to determine if and how human genes that have been inherited from both prokaryotic ancestors remain distinguishable. We show that, despite being fewer in number, human genes of archaebacterial origin are more highly and broadly expressed across tissues, are more likely to have lethal mouse orthologs, tend to be involved in informational processes, are more selectively constrained, and encode shorter and more central proteins in the protein-protein interaction network than eubacterium-like genes. Furthermore, consistent with Endosymbiotic Theory, we show that proteins tend to interact with those encoded by genes of the same ancestry. Most interestingly from a human health perspective, archaebacterial genes are less likely to be involved in heritable human disease. Taken together, these results illustrate that after more than two billion years of evolution the human genome maintains at least two somewhat distinct communities of genes.

Source

Fossils from the Yukon reveal protective plates for microscopic organisms.

In summer 2007, two geologists armed with rock hammers and a shotgun hiked through the Yukon, looking for fossils. For two weeks, Phoebe Cohen, a postdoc in MIT's Department of Earth, Atmospheric and Planetary Sciences, and Francis Macdonald, an assistant professor of geology at Harvard University, set up camp along the Alaska-Canada border in a remote mountain range accessible only via helicopter.
The shotgun came in handy: Macdonald fired it once to scare off a grizzly bear. And the rock hammers proved invaluable - the team worked them against mountainsides, chiselling out rock samples. They hauled the rocks back to Cambridge and made a surprising discovery: The ancient carbonate contained hundreds of incredibly well-preserved fossils resembling tiny, shield-like plates.
Cohen, who was a Harvard PhD student at the time, says single-celled organisms may have produced the plates as armour, in a process called biomineralisation. Today, many organisms have evolved the ability to produce mineral structures: Molluscs generate shells, and mammals and birds form bone. The 700-million-year-old fossils Cohen found may be the oldest evidence of biomineralisation; Cohen, Macdonald and co-authors reported the finding this week in the journal Geology.

 Read more 

Protein flaws responsible for complex life

Tiny structural errors in proteins may have been responsible for changes that sparked complex life, researchers say.
A comparison of proteins across 36 modern species suggests that protein flaws called "dehydrons" may have made proteins less stable in water.
This would have made them more adhesive and more likely to end up working together, building up complex function.
Read more