The study, in the Proceedings of the National Academy of Sciences, is the first to search the genome of an Antarctic notothenioid fish for clues to its astounding hardiness.
There are eight families of notothenioid fish, and five of them inhabit the Southern Ocean, the frigid sea that encircles the Antarctic continent. These fish can withstand temperatures that would turn most fish to ice. Their ability to live in the cold – and oxygen-rich – extremes is so extraordinary that they make up more than 90 percent of the fish biomass of the Southern Ocean.
University of Illinois animal biology professor Arthur DeVries discovered in the late 1960s that some notothenioids manufacture their own “antifreeze proteins.” These proteins bind to ice crystals in the blood to prevent the fish from freezing.
Cheng and her colleagues wanted to know which genes were being expressed (that is, translated into proteins) at high levels in one representative species of Antarctic notothenioid, Dissostichus mawsoni.
They analyzed gene expression in four tissues: the brain, liver, head kidney (the primary blood-forming organ in fish) and ovary of D. mawsoni.
To get a better idea of whether the genes that were “upregulated” in D. mawsoni enhanced its survival in the Antarctic, the researchers compared gene expression in D. mawsoni and in the same tissues of several unrelated, warm-water fish. They found that most of the genes that were highly expressed in the Antarctic fish were not elevated in the warm-water fish.
When they analyzed the upregulated genes, the researchers found that many of them coded for proteins that respond to environmental stress. There were many chaperone proteins, including “heat shock proteins,” for example, which protect other proteins from being damaged by stresses such as extreme cold (or heat).
Other proteins, called ubiquitins, were also expressed at higher levels in the Antarctic fish. Ubiquitins help maintain the health of cells and tissues by targeting damaged proteins for destruction.
The researchers also found very high expression of genes coding for proteins that scavenge reactive oxygen atoms or molecules in cells or alleviate oxidative cell damage or cell death. These proteins help the fish combat oxidative stress in the oxygen-rich Southern Ocean. (Oxygen dissolves much more readily in cold water, and high oxygen levels can produce highly reactive atoms or molecules that can damage cells and tissues.)
“Many of the proteins that were upregulated in the Antarctic fish are involved in maintaining the integrity of functional proteins and cells in these fish,” Cheng said.
The researchers also compared gene frequency in the Antarctic fish to that of their warm-water cousins, the three families of notothenioids that have never lived in icy waters. They found that many of the same genes that were upregulated in the Antarctic fish were also present in greater numbers than in their warm-water cousins. The actual genes had been duplicated, occurring three- to 300-fold more often in the genome of the Antarctic fish than in their warm-water cousins.
“The many more copies of these genes in the Antarctic fish would empower greater transcription and provide more of the needed protein functions,” Cheng said. “We have direct verification that these genes are indeed highly duplicated in the Antarctic species relative to their non-Antarctic cousins that have never seen cold water.”
Cheng said the findings could help scientists understand how global climate change will affect the cold-water fish.
“If you have a drastic rise in the water temperature we don’t know how well the Antarctic fish will adapt, whether they will die out or not,” Cheng said. “And if they do, then the whole Antarctic food web will be drastically affected.”
Cheng’s lab currently is conducting studies on how the fish respond to warming.
Editor’s notes: To reach C.-H. Christina Cheng, call 217-333-4245; e-mail: email@example.com or firstname.lastname@example.org.
The study, “Transcriptomic and Genomic Evolution Under Constant Cold in Antarctic Notothenioid Fish,” appeared in August in Proceedings of the National Academy of Sciences.
Diana Yates | University of Illinois
Individual Receptors Caught at Work
19.10.2017 | Julius-Maximilians-Universität Würzburg
Rapid environmental change makes species more vulnerable to extinction
19.10.2017 | Universität Zürich
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
19.10.2017 | Materials Sciences
19.10.2017 | Materials Sciences
19.10.2017 | Physics and Astronomy