DNA insights reveal what Auckland's rats are eating

Kiwi scientists are using cutting-edge DNA technology to reveal what rats around Auckland are eating, in new research that could aid conservation efforts. Photo / 123RF

Kiwi scientists are using cutting-edge DNA technology to reveal what rats around Auckland are eating, in new research that could aid conservation efforts.

The Massey University study draws upon a small Mars Bar-sized device, called the minION, which can be plugged into a laptop and quickly download a person or animal's genetic make-up.

"We thought it would be interesting to see in great depth what rats were really eating in the wild on the mainland of New Zealand," said Dr Nikki Freed, a molecular biologist involved in the joint project.

"This type of information might be interesting to look at when we start to talk about removing rats in the context of Predator Free New Zealand."

Already, the team was beginning to see how microbes in rat stomachs, along with their diets, were distinct depending on what environment they lived in.

"We also see that rats eat everything," said Freed, who discussed the work at Queenstown Research Week, an annual gathering of hundreds of scientists.

"This was known, but we see that for the 24 rats we investigated, we found that they were eating over 285 genera - plants, insects, and other animals.

"This depth at which we can see what they are eating is at a new level."

But the study hadn't come without its challenges.

One was the fact that Freed and her colleagues were essentially trying to identify diets - and microbes - by matching the sequence of DNA found in the rat's stomach to a known database.

But since so many animals and microbes were still not yet sequenced, much of the DNA found in rat stomachs did not match anything.

"So, we wind up only using about 10 per cent of the data we produce," she said.

"But, I'm very optimistic that in a few years, as more organisms get sequenced, this won't be such an issue."

As far as she was aware, no one had yet completed an analysis of rat diets using nanopore DNA sequencing.

"Additionally, it is relevant for New Zealand, as we are spending a lot of money to try and eradicate these rats.

"It might be important to know on a fine scale what they are eating, so that when these rats are removed, we might be able to link that data to changes we see in the environment once they are gone."

The study comes at a time when scientists are making new discoveries about our microbiome - or the garden of microbes that live in our gut, in our mouths, and on our skin.

There is growing evidence that these microbes might play a role in many different aspects of our lives, including our health, mood, and weight.

"We are just beginning to know what microbes are present, and the next steps are, of course, trying to better understand what they are doing there," Freed said.

"Finally, we may even be able to predict which environments these rats are living in or what they are eating based on their microbiome.

"We hope to learn more about how to use these new tools in DNA sequencing to look at what other animals are eating and what their microbes are in them.

"A first step is just to begin to be able to collect that kind of data."