Powder bones from Siberian caves helped to read the genome of neandertalci

German andn scientists have sequenced the Neanderthal genome from the Siberian cave Chagyrskaya, reported in the Proceedings of the National Academy of Sciences. You get DNA from a finger, was found in 2011. The quality of coverage for the genome is higher than that of already known genomes of the same species. It turned out that the person who owned the phalanx in life, was female, and was more closely related to Neanderthals from the Croatian caves Windy than people of the same species from Denisova cave, located just one hundred kilometers from Zagurskas. In addition, the genome of this woman suggests that Neanderthals subcortical structure of the brain called the striatum plays a special role.

In the last two decades the technology of DNA sequencing that allow you to read the genomes of long-dead organisms, collecting those of short sequences of nucleotides. So there are already two genomes of the Neanderthals and one of Denisova (species status of Homo is not yet determined) with high quality coating. There are also several genomes of Neanderthals with moderate-to-high-quality coating, in which each nucleotide on average, found in two fragments (the length of the fragments may be very different).

The quality of coverage here refers to the number of times (N), which is a single nucleotide of the genome on average was in any fragment of the latter. The genome is often represented by multiple DNA molecules — chromosomes, and they in sequencing are very rarely solid, especially in the case of ancient samples. Is not known beforehand in which order should the fragments go, is there a repeating sequence and the number of them. In addition, a portion of the DNA fragments can be lost, and all that should be considered. Therefore, those sequences that are read several times.

This takes into account the total length of the haploid genome (G) and the average length of the fragments from which it is collected (L). Medium coverage (C) for the genome is calculated by the formula C = LN / G.

Quite concise and clear about assemblies, fragments, the reads and coverages written here (in our countryn) and here (in English).

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