Scientists have captured the first high-resolution images of living Antarctic fish cells using a newly designed microscope capable of operating in near-freezing conditions.
The research, led by the British Antarctic Survey and the University of Cambridge’s Department of Chemical Engineering and Biotechnology, provides new insights into how cold-blooded animals survive year-round in the Southern Ocean, where temperatures range from -1.8ºC to 2ºC.
The findings may also offer wider insights into human biology, including how cells cope with protein misfolding, a process associated with conditions such as Alzheimer’s and Parkinson’s disease.
First Antarctic fish cells cultured
Studying cold-adapted cells has traditionally been a major technological challenge.
The new microscope enables advanced fluorescence microscopy at temperatures close to 0ºC, giving researchers a previously unavailable view inside living cold-adapted cells.
The team cultured cells from the Antarctic spiny plunderfish (Harpagifer antarcticus), a small bottom-dwelling fish found in shallow waters of the Southern Ocean and sub-Antarctic islands.
It was the first time Antarctic fish cells had ever been cultured, requiring scientists to develop a new cell culture technique that could support future research.
For comparison, cells from the shanny (Lipophrys pholis), a small fish found in shallow waters around Britain, were also cultured.
Using fluorescent dyes and the new microscope, researchers compared the structure and behaviour of the two species’ cells.
First culture breakthrough: Scientists developed a new technique to grow Antarctic spiny plunderfish cells in the laboratory, allowing detailed study of their response to extreme cold. Image: British Antarctic Survey
Cellular adaptations to extreme cold
The researchers found that Antarctic fish cells have developed several “workarounds” to cope with low temperatures and the challenges they create for normal cell function, particularly around energy production and protein folding.
The mitochondria — often described as the “cell engines” — had merged into larger, connected networks, with more mitochondria present overall.
The lysosomes, which act as the cell’s recycling systems, were also larger in Antarctic fish cells.
Researchers believe this allows cells to process and remove higher numbers of damaged or misfolded proteins produced in cold conditions.
Dr Francesca van Tartwijk, a cell biologist with the British Antarctic Survey and the University of Cambridge, explained that proteins are fundamental to cell biology.
“Proteins start off as long chains of molecules called amino acids, a bit like a string of beads. These chains then fold themselves into a precise shape, almost like origami, and this shape determines everything about what a protein can do,” she said.
“Low temperatures – like in the Southern Ocean – slow down and disrupt this process – and make mistakes in the folding more likely.”
“A misfolded protein is useless at best, but can be really harmful, so these cold-adapted cells need ways of dealing with them.”
Cold does not slow everything down
The researchers say one surprising discovery was that, although Antarctic animals are extremely slow-moving at whole-body level, movement within their cells is not.
They found that mitochondria in cold-adapted cells moved at surprisingly high speeds, while the basic organisation of molecules inside cells continued normally.
This challenges previous assumptions that adapting to cold means all cellular processes become slower.
British Antarctic Survey genetics leader Prof Melody Clark, who co-leads the “Cold Fish” project, said Antarctic animals are highly vulnerable to climate change.
“Raising temperatures just a few degrees can be lethal,” she said.
“We want to unpick why Antarctic species have such low tolerances for increases in temperature – are their limits set by their cell biology, or is it their whole-body systems, like circulation.”
Frozen frontier biology: Fluorescence imaging shows the internal structure of Antarctic fish cells, including the nucleus and cytoskeleton, under conditions close to those experienced in the Southern Ocean. Image: British Antarctic Survey
Potential human applications
The researchers say understanding how Antarctic fish cope with protein misfolding could eventually help identify techniques relevant to human diseases including Alzheimer’s, Parkinson’s and Huntington’s.
The research may also contribute to improved methods for protecting donated human tissue while stored at low temperatures.
Another potential application is in biotechnology, where many industrial processes currently operate at higher temperatures because cells and enzymes work more efficiently, although this requires greater energy use.
The team’s initial findings have been published by the British Antarctic Survey
