Archive for the ‘ Molecular Biology ’ Category

More evidence against a “metabolism first” origin of life

New research by Universitat Autònoma de Barcelona, published in the Proceedings of National Academy of Sciences, has revealed problems with origin of life hypotheses that are based on metabolic systems developing first, as opposed to an RNA or DNA system. 

The researchers found that compound genomes, or “composomes”, the basic unit of proto-life in metabolism-based hypotheses, are unable to undergo Darwinian evolution, putting serious doubt onto thoughts that they could foster the beginning of life on planet Earth.

However, this is just one study – more research needs to be done to confirm or deny these results.

Eight percent of the human genome is bornaviral in nature

Bornaviruses, a type of RNA virus that replicates inside the nucleus of host cells, has been found to be responsible for up to eight percent of the content of the human genome. Through endogenization, the virus’s DNA, retrotransposed from the RNA genome, has been integrated with our chromosomes over evolutionary time. Once the viral sequences are in the genome, they can be inherited through reproduction like any other part of the genome.

Due to the nature of bornavirus infections – they only infect neurons, the cells that comprise brain tissue – researchers have hypothesised that bornavirus genome integration could be the source of psychiatric disorders such as schizophrenia. A fascinating idea, but one that will have to be backed up with solid evidence in the future.

Prions capable of evolution

Prions, the proteins responsible for various diseases including bovine spongiform encephalopathy (aka. mad-cow disease), have been found to able to evolve via mutation and natural selection just like traditional life-forms.

Even though by most measures prions are not living organisms – they are proteins with no genetic material – the Scripps Research Institute has found they can adapt to their environment and become more dangerous over time.

Charles Weissmann, the head of the study, had this to say:

“On the face of it, you have exactly the same process of mutation and adaptive change in prions as you see in viruses. This means that this pattern of Darwinian evolution appears to be universally active. In viruses, mutation is linked to changes in nucleic acid sequence that leads to resistance. Now, this adaptability has moved one level down- to prions and protein folding – and it’s clear that you do not need nucleic acid (DNA or RNA) for the process of evolution.”

Very interesting. It’ll be fun to see what creationists and intelligent design proponents such as the Discovery Institute have to say about this find.

(via BBC News) – (h/t to @dreadpiratemick on Twitter)