Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Genes hold secret to survival of Antarctic 'antifreeze fish'

17.10.2008
A genetic study of a fish that lives in the icy waters off Antarctica sheds light on the adaptations that enable it to survive in one of the harshest environments on the planet.

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.

In the new study, U. of I. animal biology professor C.-H. Christina Cheng and her colleagues at the Chinese Academy of Sciences sought comprehensive genetic clues that would help explain how the Antarctic notothenioids survive.

“Nobody has ever actually looked at the whole range of biological functions in these fish that are important for living in this chronically cold environment,” Cheng said. “This is the first study that does that.”

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.

“We saw this very peculiar profile where in each of these tissues the proteins that are highly expressed are from a small set of genes,” Cheng said. “Each tissue makes all kinds of transcripts – the genetic messages that are made into proteins – but we found that a small group of genes dominates the transcriptional process.”

The researchers reasoned that any proteins that gave the fish an advantage in a cold, oxygen-rich environment would be expressed at high levels in the Antarctic fish. But it could also be true that specific tissues simply expressed more of certain proteins.

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: c-cheng@illinois.edu or cdevries@life.illinois.edu.

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
Further information:
http://news.illinois.edu/news/08/1016antarcticfish.html

More articles from Life Sciences:

nachricht Biochemical 'fingerprints' reveal diabetes progression
22.08.2017 | Umea University

nachricht When fish swim in the holodeck
22.08.2017 | University of Vienna

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Molecular volume control

22.08.2017 | Life Sciences

When fish swim in the holodeck

22.08.2017 | Life Sciences

Biochemical 'fingerprints' reveal diabetes progression

22.08.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>