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Even with loads of fish within the sea, sea dragons stand out from the gang.
The funky, fabulous fish are bedecked with ruffly leaf-like adornments. Their spines are kinked. They’re lacking their ribs and their tooth. And the accountability of being pregnant is taken on by the males.
By sequencing the genomes of two species of sea dragons, University of Oregon (UO) researchers have discovered genetic clues to the fish’s distinctive options: They’re lacking a key group of genes present in different vertebrates. Those genes assist direct the event of the face, tooth and appendages, in addition to elements of the nervous system.
Sea dragons belong to the identical household as sea horses and pipefish. “This group is simply cool for a lot of totally different causes,” mentioned Clay Small, a analysis assistant professor and member of biology professor Bill Cresko’s lab. “But sea dragons are oddballs in a gaggle of already oddball fish.”
Small led the undertaking alongside senior analysis affiliate Susie Bassham.
“There’s quite a lot of curiosity in how malleable to evolution issues like the pinnacle and face are,” Bassham mentioned.
And sea dragons could be good case research for that form of query due to the intense variations they’ve developed pretty shortly. The household that sea dragons and sea horses belong to branched off about 50 million years in the past, which is comparatively lately by evolutionary requirements.
Bassham, Small and their colleagues report their findings June 22 within the journal Proceedings of the National Academies of Sciences.
In the wild, sea dragons solely reside off the coast of Australia. That’s made them tough to check. But Cresko’s lab bought uncommon entry to tissue samples by collaborating with scientists from the Birch Aquarium at Scripps and the Tennessee Aquarium, which elevate sea dragons in captivity.
The researchers sequenced the genomes of two sea dragon species, leafy and weedy sea dragons. They in contrast these genetic sequences to pipefish and sea horses, in addition to different much less carefully associated bony fish equivalent to zebrafish and stickleback.
Along with pipefish and sea horses, sea dragons have been lacking a piece of genes that information growth, a potential clue to the origins of their distinctive type.
Compared to their shut kin, sea dragons additionally contained higher-than-usual quantities of repetitive DNA sequences known as transposons. These sequences, also called “leaping genes,” typically copy themselves or transfer round within the genome. They could cause fast genetic adjustments once they insert themselves in the midst of or close to a gene, stopping the gene from working as ordinary.
The workforce additionally used a specialised X-ray microscope on the UO’s Knight Campus to seize a high-resolution 3D picture of a weedy sea dragon. They scanned the foot-long fish in sections, then stitched the pictures collectively into a whole image.
“Nobody had ever imaged any a part of a sea dragon earlier than that manner, with such excessive decision,” Bassham mentioned.
At that stage of element, they might see the advantageous construction of the ocean dragon’s bones, and likewise get perception into how a few of the fish’s distinctive physique buildings may need developed.
“We might see that the help buildings for the leafy paddles gave the impression to be gildings of spines, after which the fleshy appendages have been added to the ends,” Bassham mentioned. “It lent proof to concept that these (ornaments) are evolutionarily derived from spines.”
The UO scientists hope making sea dragons’ genome sequences publicly accessible shall be helpful for additional analysis not solely in evolution and developmental genetics however maybe additionally within the effort to grasp and preserve the uncommon fish.
San Diego aquarium breeds uncommon weedy sea dragon in captivity
More info:
Clayton M. Small et al, Leafy and weedy seadragon genomes join genic and repetitive DNA options to the extravagant biology of syngnathid fishes, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2119602119
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Sea dragons’ genes give clues to their distinctive appears to be like (2022, June 27)
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