Researchers
have sequenced the genome of a little squid to identify unique evolutionary
footprints in symbiotic organs, yielding clues about how organs that house
bacteria are especially suited for this partnership.
In a
new study, an international team of researchers, led by UConn associate
professor of molecular and cell biology Spencer Nyholm, sequenced the genome of
this little squid to identify unique evolutionary footprints in symbiotic
organs, yielding clues about how organs that house bacteria are especially
suited for this partnership.
By
comparing the genome of E. scolopes to its cousin, the octopus, the
researchers show that the common ancestor of both the octopus and the Hawaiian
bobtail squid went through a major genetic makeover, reorganizing and
increasing the genome size. This "upgrade" likely gave the
cephalopods opportunities for increased complexity, including new organs like
the ones that house bacteria.
Many
animals have organs that house bacteria. The human gut houses trillions of
bacteria that play important roles in digestion, immune function, and overall
health. Understanding how these relationships are maintained by identifying
genes that help animals cooperate with bacteria lays the groundwork for
furthering knowledge of the human body. The Hawaiian bobtail squid is an
excellent model for identifying these genes because of its symbiotic
relationships with beneficial microbes, and its use by a number of scientists
to study communication between bacteria and animals.
The
Hawaiian bobtail squid has two different symbiotic organs, and researchers were
able to show that each of these took different paths in their evolution. This
particular species of squid has a light organ that harbors a light-producing,
or bioluminescent, bacterium that enables the squid to cloak itself from
predators. At some point in the past, a major "duplication event"
occurred that led to repeat copies of genes that normally exist in the eye. These
genes allowed the squid to manipulate the light generated by the bacteria.
Another
finding was that in the accessory nidamental gland, a female reproductive
organ, there was an enrichment of genes that are "orphan genes" or
genes that have only been found in the bobtail squid and not in other
organisms.
See:
Posted by Dr. Tim Sandle, Pharmaceutical Microbiology
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