The genome of a blind Australian marsupial that is rarely spotted in its remote Australian habitat could help uncover new genes tied to human eyesight.
An international collaboration of researchers, including several from Australia, has published a paper1 on the genetic adaptations that enable the Australian marsupial mole to thrive underground.
All mammals, including humans, share a core set of genes responsible for producing and maintaining our eyes. In this blind subterranean species, however, those genes are degrading. By studying their DNA sequences, the changes are clearly illustrated, and it has led the team to identifying eye-related genes that had never been discovered before, explained co-author Associate Professor Nathan Clark from the University of Pittsburgh in the United States.2
“If something falls out of use [such as eyesight in the marsupial mole], the remnants of that gene stick around for a while, and we can see that,” said Assoc Prof Clark.
“Part of our mission is to uncover new parts of the genome that help us form and maintain our eyesight. It turns out that we have a lot of different eye abnormalities that are genetically encoded, and it depends on which disease, but roughly half of those go undiagnosed at the genetic level.”
To better understand the genetics behind the degeneration of the marsupial mole eyes, the researchers started with human genes because “they are some of the best characterised and studied version of the genes in science”, explained co-author Dr Sarah Lucas, from the University of Münster in Germany.
“For this study we wanted to focus on the eye, so we restricted the genes we were interested in, to those which are only expressed in the human eye and in no other tissue. Next, we had to determine which of those genes are also found in marsupials.”
That left the team, she said, “with 30 genes to study”.
Once the focus was narrowed, the team then honed in on “helping fill out that catalogue of ocular genes so that we can locate [the culprit gene or genes] when things go wrong,” Assoc Prof Clark said.
Among the notable discoveries are “two positions in the marsupial mole in which the corresponding change in humans results in an eye disease,” Dr Lucas said. “Both positions reside in the GJA8 gene, which encodes for a protein necessary for the growth and maturation of the lens. A human possessing either one of these variants is likely to go on to develop cataracts, or cloudiness of the eye.”
According to the team, the northern marsupial mole is distributed in northwestern Australia and very rarely seen. The southern marsupial mole can be found across central and southern Australia. Efforts to capture and study the moles in captivity have been wholly unsuccessful. Their endangered status also hindered collection efforts. The team instead obtained a female marsupial mole specimen from the South Australia Museum in Adelaide.
References
1. Frankenberg SR, Lucas S, Pask AJ, et al. Unearthing the secrets of Australia’s most enigmatic and cryptic mammal, the marsupial mole. Sci Adv. 2025 Jan 3;11(1):eado4140. doi: 10.1126/sciadv.ado4140.
2. Burkhart R, How a blind Australian mole helps researchers ‘see’, Pittsburg Post Gazette, 25 Jan 2025, available at: post-gazette.com/news/health/2025/01/25/australian-marsupial-mole-dna-eyesight-genes/stories/202501190026 [accessed Jan 2025].
