Unfortunately, last week was so much other stuff that I do not have time for a post on Charles Darwin's birthday. Instead now belatedly to write about a man who over the past weeks already written so incredibly much, was that it was the most probably to his neck out is [1], I will briefly report on an event last Thursday was held in time for Darwin Day .
The Max-Planck-Institut for Evolutionary Anthropology in Leipzig announced in a press release ( streaming video ) the draft sequence of the Neanderthal genome. The first is a bit questionable, since the announcement of results in the press before a full-fledged publication in a peer review journal is not a model act for a scientist. Here you can squeeze at least one eye, I think - the appointment of Darwin's birthday was just too tempting, also carried the press conference also simultaneously at the annual meeting of the American Association for the Advancement of Science (AAAS), which publishes, among other things, the Science Magazine . Still, a funny feeling remains in the stomach.
Apart from that the whole thing is of course very exciting. Just three years Svante Pääbo announced by the Department of Evolutionary Genetics to the MPI, it will sequence the Neanderthal genome. This is only possible in such a short time (remember the work of the Human Genome Project in the 90's lasted about 10 years), because now new, faster sequencing methods are available. These so-called second-generation sequencing technologies, but all suffer from the problem that they produce very short sequence pieces (20-50 base pairs). And here it helps the hard preparatory work of the Human Genome Project, as can be with the human reference genome be composed of the Neanderthal genome with very short sequences. One expects very few differences between the two genome sequences, the genomes of humans and chimpanzees are, after all very similar.
To get Neanderthal sequences, but they must first several problems can be avoided. Contamination by human DNA of the researchers involved would be fatal, so had the Neanderthal samples are processed in clean room conditions. Nevertheless, the bones were very, very long in the soil around, the samples contain about a lot mikrobiolle DNA. The course was mitsequenziert first, but could be removed through bioinformatic methods again: Bacterial genomes are compared with the human very small, and there have already been sequenced many. By the Leipzig researchers compared their sequences with bacterial genome sequences, they could detect impurities in their data and then discard. These impurities make up about 90% of the sequenced material! If one also considers that the group led by Svante Pääbo of DNA isolation protocols for incorrect about 99% loss was , it's amazing how far they have come in the short term.
It must, however, expressly stated that it is best, is a first draft sequence. About 60% of the genome sequenced, but this only once. In order to methodological errors to protect the sequencing technologies, should each nucleotide in a genome sequence can be sequenced, but several times (the human reference sequence, incidentally 12x coverage). Another problem is to estimate sequence differences between individuals of a species the variability of the genome sequence of a species to as many individual sequences should be present. This is currently in progress in the human genome, such as the Human Genome Project or the 1000 Genomes Project . Even the first human genome reference is in fact a mixture of the sequences of twelve anonymous individuals dar. soon but is also the sequencing of other Neanderthal samples Begin so that this problem should be well resolved at some point.
A big problem is not to remain anonymous also: Due to the great age of the samples, the DNA is fragmented and it is therefore very likely that we never had the complete genome sequence of the Neanderthal are obtained.
Nevertheless it is possible already to this first data to follow up interesting questions about the relationship between Homo sapiens and Homo neanderthalensis . In much of Europe, both human species lived side by side for several thousand years. It came to a hybridization, that is common to progeny of both species? If the modern man, perhaps even Neanderthals as ancestors? The recent sequence data (based on mitochondrial sequences and the Y chromosome) indicate more towards no.
The expression of the gene MC1R (melanocortin 1 ) that affects the degree of skin pigmentation, showed that there were possibly light-skinned and red-haired Neanderthals (Lalueza-Fox C et al (2007), Science 318:1453-5).
Finally, I would (yes you guessed it,) with this post - a podcast! About two years ago, is still relatively early in the Neanderthal genome project, Svante Pääbo, together with Thomas Jarvie (from 454 Life Sciences, which represent the sequencing available) in the always good Futures interviewed in Biotech podcast [MP3 link ]. I have not heard since the interview will, but maybe listen again. Let's see how Pääbos could keep up plans two years ago with the actual development.
[1] The public attention that Darwin and evolution is certainly true and just enjoy good, but I'm looking forward to the next, quieter weeks. Until it in late then with the 150th anniversary of Origin release goes around again.
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