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Evolution faster than thought
Posted on January 1st, 2010 No comments2010-01-01 22:18 news24.com
Berlin – A team of German and US scientists has discovered that genetic mutation – the basic process of evolution – occurs much faster than previously thought, according to a study published on Friday.
The team of researchers from the Max Planck Institute for Molecular Biology in Tuebingen and the University of Indiana studied genome mutation in a species of cress (Arabidopsis thaliana), and found that each gene in the plant will mutate on average once in every 143 million generations.
Genomes are the complete set of genetic information for any organism, consisting of individual genes found in DNA.
“While the long-term effects of genome mutations are quite well understood, we did not know how often new mutations arise in the first place,” project leader Detlef Weigel of the Max Planck Institute said in a press statement.
Thousands of years
The discovery means that for many plant species, whose millions of individual members produce thousands of seeds with each generation, an entire genome mutation can occur within a relatively short space of time.
“Evolution reveals itself only after thousands, not millions of years,” Weigel said.
Such a rate of genetic change can explain how species adapt to changing circumstances quickly, and the study gives the example of weeds becoming resistant to specific herbicides within just a few generations.
60 new mutations in humans
The team used new methods to track all the genetic changes in five “lines” (plants with common ancestors) of Arabidopsis thaliana over 30 generations. In the final generation they searched for differences to the original plants.
“To ferret out where the genome had changed was only possible because of new methods that allowed us to screen the entire genome with high precision and in a very short time,” Weigel said.
The team said that the same speed of genetic change could in theory be expected in human DNA, meaning that with six billion people on earth each form of human gene would be permanently mutating somewhere on the planet.
“If you apply our findings to humans, then each of us will have in the order of 60 new mutations that were not present in our parents. Everything that is genetically possible is being tested in a very short period,” said Indiana University’s Michael Lynch. Max Planck Society:
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DNAWellnessinfo.com Resource: http://www.news24.com/Content/SciTech/News/1132/fde544679f8e47fb9d0155d6adc6171a/01-01-2010-10-18/Evolution_faster_than_thought
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DNA Sequencing Answers Confounding Questions About Human Evolution
Posted on December 31st, 2009 1 commentBy News Staff | December 31st 2009 12:00 AM – Scientificblogging.comA team of anthropologists has for the first time directly analyzed DNA from a member of our own species who lived around 30,000 years ago, allowing scientists a unique glimpse into the history of evolution. Their research is detailed in the December 31 issue of Current Biology.DNA–the hereditary material contained in the nuclei and mitochondria of all body cells–is a hardy molecule and can persist, conditions permitting, for several tens of thousands of years. Such ancient DNA provides scientists with unique possibilities to directly glimpse into the genetic make-up of organisms that have long since vanished from the Earth, but the ancient DNA approach could not be easily applied to ancient members of our own species.
This is because the ancient DNA fragments are multiplied with special molecular probes that target certain DNA sequences. These probes, however, cannot distinguish whether the DNA they recognize comes from the ancient human sample or was introduced much later, for instance by the archaeologists who handled the bones. Thus, conclusions about the genetic make-up of ancient humans of our own species were fraught with uncertainty.
Using the remains of humans that lived in Russia about 30,000 years ago, Svante Pääbo and his colleagues made use of the latest DNA sequencing (i.e., reading the sequence of bases that make up the DNA strands) techniques to overcome this problem. These techniques, known as “second-generation sequencing,” enable the researchers to “read” directly from ancient DNA molecules, without having to use probes to multiply the DNA.
Moreover, they can read from very short sequence fragments that are typical of DNA ancient remains because over time the DNA strands tend to break up. By contrast, DNA that is younger and only recently came in contact with the sample would consist of much longer fragments. This and other features, such as the chemical damage incurred by ancient as opposed to modern DNA, effectively enabled the researchers to distinguish between genuine ancient DNA molecules and modern contamination. “We can now do what I thought was impossible just a year ago – determine reliable DNA sequences from modern humans – but this is still possible only from very well-preserved specimens,” says Pääbo.
The application of this technology to the remains of members of our own species that lived tens of thousands of years ago now opens a possibility to address questions about the evolution and prehistory of our own species that were not possible with previous methods, for instance whether the humans living in Europe 30,000 years ago are the direct ancestors of present-day Europeans or whether they were later replaced by immigrants that brought new technology such as farming with them.
Citation: Johannes Krause, Adrian W. Briggs, Martin Kircher, Tomislav Maricic, Nicolas Zwyns, Anatoli Derevianko, Svante Pääbo, ‘A Complete mtDNA Genome of an Early Modern Human from Kostenki, Russia’, Current Biology, Online 31 Dec. 2009; doi:10.1016/j.cub.2009.11.068
DNAWellnessinfo.com Resource: http://www.scientificblogging.com/news_articles/dna_sequencing_answers_confounding_questions_about_human_evolution
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