Dinosaur relative's genome linked to mammals

August 05, 2020

Scientists from the University of Adelaide and South Australian Museum have collaborated with Otago University, New Zealand and a global team to sequence the genome of the tuatara - a rare reptile whose ancestors once roamed the earth with dinosaurs.

The findings on this remarkable living, single species reptile, which originated in the Triassic period around 250 million years ago and is only found in New Zealand, have been published in Nature.

Professor David Adelson's lab of the University of Adelaide's Department of Molecular and Biomedical Science and Dr Terry Bertozzi of the South Australian Museum carried out key analysis of the tuatara genome that revealed an unusual architecture, half-way between mammal and reptile.

"The tuatara is the last surviving species of a reptile group that roamed the earth with the dinosaurs and remarkably, its genome shares features with those of mammals such as the platypus and echidna," said Professor Adelson.

The key contribution of Professor Adelson's lab and Dr Bertozzi was to demonstrate that some sequences of DNA that move or jump location, referred to as 'jumping genes', found in the tuatara are most similar to those found in platypus while others are more similar to those in lizards.

"The tuatara genome contained about 4% jumping genes that are common in reptiles, about 10% common in monotremes (platypus and echidna) and less than 1% common in placental mammals such as humans," said Professor Adelson.

"This was a highly unusual observation and indicated that the tuatara genome is an odd combination of both mammalian and reptilian components."

"The unusual sharing of both monotreme and reptile-like repetitive elements is a clear indication of shared ancestry albeit a long time ago," said Dr Bertozzi.

With no close relatives, the position of tuatara on the tree of life has long been contentious. The research places tuatara firmly in the branch shared with lizards and snakes, but they appear to have split off and been their own species for around 250 million years - an enormous amount of time given primates only originated around 65 million years ago, and hominids, from which humans descend, originated approximately six million years ago.

"It has been a privilege to be part of this project, which has been a true, historic collaboration with local iwi (Māori indigenous tribe) Ngātiwai. While this is largely fundamental science, I expect it to yield new ways of thinking about our own genome structure that may have relevance to our health," said Professor Adelson.

University of Adelaide

Related Genome Articles from Brightsurf:

Genome evolution goes digital
Dr. Alan Herbert from InsideOutBio describes ground-breaking research in a paper published online by Royal Society Open Science.

Breakthrough in genome visualization
Kadir Dede and Dr. Enno Ohlebusch at Ulm University in Germany have devised a method for constructing pan-genome subgraphs at different granularities without having to wait hours and days on end for the software to process the entire genome.

Sturgeon genome sequenced
Sturgeons lived on earth already 300 million years ago and yet their external appearance seems to have undergone very little change.

A sea monster's genome
The giant squid is an elusive giant, but its secrets are about to be revealed.

Deciphering the walnut genome
New research could provide a major boost to the state's growing $1.6 billion walnut industry by making it easier to breed walnut trees better equipped to combat the soil-borne pathogens that now plague many of California's 4,800 growers.

Illuminating the genome
Development of a new molecular visualisation method, RNA-guided endonuclease -- in situ labelling (RGEN-ISL) for the CRISPR/Cas9-mediated labelling of genomic sequences in nuclei and chromosomes.

A genome under influence
References form the basis of our comprehension of the world: they enable us to measure the height of our children or the efficiency of a drug.

How a virus destabilizes the genome
New insights into how Kaposi's sarcoma-associated herpesvirus (KSHV) induces genome instability and promotes cell proliferation could lead to the development of novel antiviral therapies for KSHV-associated cancers, according to a study published Sept.

Better genome editing
Reich Group researchers develop a more efficient and precise method of in-cell genome editing.

Unlocking the genome
A team led by Prof. Stein Aerts (VIB-KU Leuven) uncovers how access to relevant DNA regions is orchestrated in epithelial cells.

Read More: Genome News and Genome Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.