- Scientists have recreated the genome of the Christmas Island rat, which went extinct more than 100 years ago.
- But about 5% of the rat’s genetic makeup could not be recreated, which means if the animal were brought back to life, it would be different.
- Gene splicing technology could be used to substitute what’s missing, but the result may not be an exact copy of its ancient predecessor.
Last year, we learned that scientists wanted to bring back the woolly mammoth. Now, researchers have set their sights on resurrecting something much smaller: the Christmas Island rat, a rodent which measured about 10 inches in length, not counting its 7-inch tail.
To test the viability of improving gene-splicing technology, researchers focused on the Christmas Island rat. The coarsely haired critter went extinct more than 100 years ago on that island in the Indian Ocean, scientists think because of diseases brought by European ships.
But the Christmas Island rat has a close evolutionary descendent in the Norway rat. That larger rat, which can weigh more than a pound and be 16 inches long, is the species that dwells in our sewers and has become a common laboratory research subject.
Using gene-editing technology, researchers attempted to recreate the genome of the Christmas Island rat and found that the two rats shared about 95% of the same genetic material. But they also found that about 5% of its original genes could not be recovered, they reported Wednesday in Current Biology, the peer-reviewed scientific journal.
“They have evolved to be so different, we can’t recover the sequence,” said Tom Gilbert, one of the study’s co-authors and the head of the Center for Evolutionary Hologenomics at the University of Copenhagen in Denmark.
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So, don’t start itching to book your tickets to Jurassic Park just yet. Without a totally accurate genome, scientists cannot predict what might be brought to life.
Researchers will want to do similar experiments to approximate how close a replica of the extinct animal they will create, Gilbert said in an email interview.
“And you can then decide if you are happy with that as the end goal. You may be … or you may feel it’s not quite what you wanted,” he said. “But the point is – this analysis is not hard to do and can be quite informative.”
What it takes to resurrect a rat
The researchers at the University of Copenhagen and Shantou University in China used DNA from two dried Christmas Island rat skins to sequence its genome and compare it to the modern Norway rat. In comparing the two, the researchers found that some of the missing Christmas Island rat genes dealt with its ability to smell.
So a reborn Christmas Island rat might “lack attributes likely critical to surviving in its natural or natural-like environment,” they write in the report.
However, using CRISPR gene editing technology, the rat to be brought back could be a hybrid animal including the immunity genes of the Norway rat, which “could even have some potential benefit,” they wrote.
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But first, Gilbert plans to try editing the genome of a black rat to change it into a Norway rat, he said in a description of the research on the university’s website. “It’s a fascinating idea in technology, but one has to wonder if that’s the best use of money as opposed to keeping the things alive that are still here,” he said.
Is bringing back species the best strategy?
Ross MacPhee, a senior curator at the American Museum of Natural History and a co-author of the study, wondered whether gene editing technology might not be better spent helping current species such as the endangered California condor, he told NBC News.
“There are situations where you’d dearly love a species to do better, but we also need to recognize that it’s what people have done to the environment that has limited the opportunities for these species to have any kind of decent life,” MacPhee said .
Colossal Laboratories, the company behind the effort to use elephant DNA to bring back mammoths is not deterred. Gene sequencing technology for ancient and modern DNA is “steadily improving,” Harvard Medical School biologist and Colossal co-founder George Church told Science.
Colossal is working on transferring the genes in mammoths that allow them to tolerate the cold into modern elephants. “The main goal is not making ‘perfect photocopies,’ but making diverse and selective hybrids,” Church said.
Follow Mike Snider on Twitter: @mikesnider.