Nova Scotia scientists discover new branch to tree of life

HALIFAX (NEWS 1130) — Scientists at Dalhousie University have discovered a new branch on the evolutionary tree of life after unraveling the genes of a rare microscopic creature.

Two species of the complex, single celled organisms called hemimastigotes were found in soil samples gathered on a trail in the forests around Halifax. Their genes turned out to be so different that the researchers believe they may have branched off from all life’s common ancestor more than a billion years ago.

“Animals and fungi are much more closely related to each other than anything we know about was related to (hemimastigotes),” said Dalhousie biology professor Alastair Simpson, a co-author of the study published this week in the journal Nature.

Scientists have known about hemimastigotes since the 19th century, but up until today they were guessing where the creatures fit on the chain of evolution.

“The reason we didn’t have genetic information on these organisms before is because no one could grow them in the lab,” Simpson said. “But quite recently there have been new techniques developed to allow you to get lots of genetic information from just one, two or four individual cells. So we used those techniques to get lots of genetic information from each of the two species before we could culture them.”

Conducting a phylogenetic analysis on around 100 different genes, the scientists found the hemimastigotes didn’t fit on any known evolutionary branch.

Scientists can tell how healthy ecosystems are by knowing what microbes are in the environment

“Microbes are hugely important to the ecology of the planet and now that we have genetic sequences from this major group for the first time, it will let other scientists identify when they group is present in their samples,” Simpson said.

“It will give a lot of scientists a little better view of what’s in their samples and that will allow them a better understanding of how those microbes are interacting which ultimately leads to how those ecosystems run.”

He says understanding how the ecosystems run, and what’s in them, also allows scientists to know whether the environment is healthy.

Initially unbeknownst to the researchers, the soil they collected two years ago contained the two species. After leaving the samples in water for a month, a technique used to bring dormant organisms to life, they found the tiny creatures under the microscope.

Although it’s only speculation, Simpson hypothesizes the reason the creatures are hard to find is because of their diet.

“The species we studied are predators of other complex celled microbes,” he said.

“They don’t eat bacteria or photosynthesize, they scurry around in the environment and eat other complex celled microbes. So in order for them to be able to grow in a sample, they need to have their prey there and they’re probably quite specific about which species they’re willing to eat.”

Each of the species was covered in flagella, tiny hair-life appendages similar to the tails of sperm, which help propel them through their microscopic environment and catch prey.

The team identified one of the species, but the other was newly discovered. Its ‘hairy’ appearance and voracious hunting prompted the research team to name it Hemimastix kukwesjijk after Kukwes, a greedy, hairy, man-eating ogre from local Mi’kmaq folklore. The name kukwes is a diminutive form of Kuku, meaning giant, so translating into little giant.

Now that researchers are able to feed the hungry little microbes, Simpson says they have been able to grow an entire culture. The creatures are being shared with other labs to sequence the rest of its genome and better understand the species.

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