The tube anemone Isarachnanthus nocturnus is only 15 cm long but has the largest mitochondrial genome of any animal sequenced to date, with 80,923 base pairs. The human mitochondrial genome (mitogenome), for example, comprises 16,569 base pairs.
Tube anemones (Ceriantharia) are the focus of an article recently published in Scientific Reports describing the findings of a study led by Sérgio Nascimento Stampar, a professor in São Paulo State University's School of Sciences and Letters (FCL-UNESP) at Assis in Brazil.
Study - FAPESP - Grant - Project - Evolution
The study was supported by FAPESP via a regular grant for the project "Evolution and diversity of Ceriantharia (Cnidaria" and via its program São Paulo Researchers in International Collaboration (SPRINT) under a cooperation agreement with the University of North Carolina (UNC) at Charlotte in the US.
The mitogenome is simpler than the nuclear genome, which in the case of I. nocturnus has not yet been sequenced, Stampar explained. The human nuclear genome comprises some 3 billion base pairs, for example. Another discovery reported in the article is that I. nocturnus and Pachycerianthus magnus (another species studied by Stampar's group, 77,828 base pairs) have linear genomes like those of medusae (Medusozoa), whereas other species in their class (Anthozoa) and indeed most animals have circular genomes.
I - Nocturnus - Atlantic - Coast - Patagonia
I. nocturnus is found in the Atlantic from the coast of Patagonia in Argentina as far north as the East Coast of the US. P. magnus lives in the marine environment around the island of Taiwan in Asia. Both inhabit waters at most 15 m deep.
"I. nocturnus's mitogenome is almost five times the size of the human mitogenome," Stampar said. "We tend to think we're molecularly more complex, but actually our genome has been more 'filtered' during our evolution. Keeping this giant genome is probably more costly in terms of energy expenditure."
Shape - Mitogenomes - Species
The shape of the mitogenomes in these two species of...
(Excerpt) Read more at: phys.org