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: firstname.lastname@example.org or email@example.com.
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
Scientists enlist engineered protein to battle the MERS virus
22.05.2017 | University of Toronto
Insight into enzyme's 3-D structure could cut biofuel costs
19.05.2017 | DOE/Los Alamos National Laboratory
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.
In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...
Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...
For the first time, scientists have succeeded in studying the strength of hydrogen bonds in a single molecule using an atomic force microscope. Researchers from the University of Basel’s Swiss Nanoscience Institute network have reported the results in the journal Science Advances.
Hydrogen is the most common element in the universe and is an integral part of almost all organic compounds. Molecules and sections of macromolecules are...
22.05.2017 | Event News
17.05.2017 | Event News
16.05.2017 | Event News
22.05.2017 | Materials Sciences
22.05.2017 | Life Sciences
22.05.2017 | Physics and Astronomy