The advance will make it possible to find the genetic basis for some of the animal's amazing regenerative abilities and immunity features, which potentially could be applied to human medicine.
Botryllus schlosseri fuses together with others to form colonies that look like psychedelic blobs, encrusting rocks and seaweeds. It can reproduce asexually, and an entire individual can be regenerated from its blood vessels alone.
In total, the group led by Stanford scientists sequenced the animal's 580 million base pairs of DNA. (The human genome, by comparison, consists of more than 3 billion base pairs.)
The researchers compared the Botryllus genome with several vertebrate and invertebrate genomes.
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Focusing on genes involved in various human diseases - affecting things such as heart and eye development, pregnancy and cancer - they found homologous genes for each in Botryllus, far more matches than in any of a dozen other invertebrates commonly used in research.
An additional investigation of blood-related genes revealed that Botryllus was probably the first invertebrate to have vasculature in the same context of the human circulatory system, with blood cells travelling through blood vessels.
"And it can do this relatively fast, probably using stem cells. Now that we have the genome, we can try to understand the mechanism behind it," Voskoboynik said.
The study of Botryllus' genome could also lead to advances in transplant medicine. When two genetically distinct Botryllus colonies come into contact with each other, they either fuse their blood vessels to create a single organism, or reject one another and maintain individuality.
When the blood vessels between the two colonies fuse into one interconnected network, the stem cells from each partner colony begin to circulate throughout the other.
A similar process occurs in humans who undergo an allogeneic transplant when a patient receives tissue or cells from a non-identical donor.
The study was published in the journal eLIFE.