Sea urchin genome analyzed
Researchers have analyzed the 814 million base pairs of sea urchin DNA, deciphering the first echinoderm genome. This group of animals, along with all vertebrates including humans, is one of the so-called Neumund animals, which differ significantly from the second large collection of Urmund animals. According to the participating scientists ., the differences and similarities between the two major subcategories of multicellular life are now also genetically comprehensible thanks to the sequencing work.
In the examined sea urchin of the species Strongylocentrotus purpuratus, the genetic analyzers of the international sequencing consortium identified 23,300 genes, of which 7077 can also be found analogously in human DNA.
The genes of the echinoderm's immune system turned out to be surprisingly diverse. In addition to the expected large number of sections in which molecules of the so-called innate immune system are encoded - an original branch of the body's defense system - the scientists also found typical genes for an adaptive defense. This form of the immune system, which is actually typical of vertebrates, reacts specifically to intruders with tailor-made, increasingly produced antibodies and defense cells. Many of the control genes responsible for such reactions are also found in sea urchins, the researchers are amazed. However, the sea urchins do not have the hereditary disposition for the production of antibodies – a core part of the adaptive defense system.
The echinoderms also carry DNA sequences that are assigned to certain sensory functions in humans – such as genes for taste, hearing, balance and vision. The vision genes are activated in the feet of the eyeless animals and enable the sea urchin to perceive light and dark.
The researchers led by Viktor Stolc from the Ames Genome Research Facility mapped the activity patterns of the sea urchin genes in the first two days of an embryo after fertilization using messenger RNA analyses. The resulting "transcriptome" proves that around half of the animal's genes are read in the first 48 hours .
The researchers benefited in their work from advances in sequencing technology: none of the transcriptomes previously created by other organisms has been created in such a short time as that of the sea urchin. (yo)