Genetic study reveals how Antarctic antifreeze fish survives icy watersOctober 17th, 2008 - 2:08 pm ICT by ANI
Washington, Oct 17 (ANI): 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 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.
Dissostichus mawsoni, the Antarctic toothfish, is the largest of the notothenioid fish to inhabit the Southern Ocean.
University of Illinois (U. of I.) 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.
Cheng and her colleagues wanted to know which genes were being expressed 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, she added.
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.
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. (ANI)
- Genes hold secret of survival of Antarctic 'antifreeze fish' - Oct 17, 2008
- Now climate change threatens Antarctica fish - Feb 14, 2012
- Why don't fish in the Arctic Ocean freeze? - Aug 26, 2010
- Microbe's 'weird chemistry' discovered - Aug 31, 2012
- Genetic change helps lung tumors spread to other parts of the body - Apr 07, 2011
- Evidence from octopus hints at ice sheet collapse - May 10, 2012
- Agreement to create biggest marine reserve at Antarctica - Nov 04, 2011
- Protein involved in melanoma's development identified - Dec 24, 2010
- Molecular predictor of metastatic prostate cancer identified - Feb 03, 2011
- Stress, depression can shrink brain - Aug 13, 2012
- Scientists identify genes that let creepy-crawlies in Arctic survive deep freeze - Jul 21, 2009
- How hormonal and molecular responses to exercise differ by age - Jan 26, 2011
- New genetic strategy makes T-cells resistant to HIV infection - Jan 27, 2011
- Oceans went oxygen-poor '499mn yrs ago after animals appeared on Earth' - Jan 06, 2011
- Blame defective gene for malformed faces - Jul 06, 2012
Tags: adaptations, animal biology, antarctic continent, antifreeze, antifreeze proteins, biology professor, chinese academy of sciences, fish biomass, gene expression, genetic clues, genetic messages, genetic study, hardiness, liver head, ovary, professor arthur, professor c, representative species, southern ocean, toothfish