Doctors discover the secret of why goldfish survive in winter without oxygen
Goldfish have the ability to survive in deep ice in ice-covered lakes. Scientists are now researching the secrets behind this ability. Goldfish therefore convert the lactic acid in their body into alcohol in order to stay alive in winter.
Scientists at the University of Liverpool and the University of Oslo found that goldfish can convert lactic acid in their bodies to alcohol to survive in frozen lakes in winter. The doctors published the results of their study in the scientific journal "Scientific Reports".
Goldfish have a special ability to survive
Since the 1980s, experts have known about the special survivability of goldfish and their wild relatives living in nature, which are known as crucian carp. Humans and most vertebrates die within minutes if they are deprived of oxygen. Goldfish, on the other hand, can survive for months in icy conditions in ponds and lakes in Northern Europe without their organism being supplied with oxygen, the authors explain.
In the absence of oxygen, the consumption of carbohydrates creates lactic acid in the goldfish
Researchers have now discovered the mechanism behind this interesting survivability. Most animals have only one set of proteins that carry carbohydrates towards the mitochondria, which are the energy generators of cells. In the absence of oxygen, the consumption of carbohydrates causes lactic acid, which goldfish cannot break down, the scientists explain. Lactic acid would normally kill the goldfish within a few minutes.
Proteins convert lactic acid to alcohol
Goldfish have developed a second set of proteins that can convert lactic acid to alcohol in the absence of oxygen. The alcohol produced is then released through the gills. This ability is only activated by lack of oxygen, experts from the University of Liverpool say. When goldfish can no longer get oxygen through an ice sheet, the fish consumes all the oxygen and then switches to alcohol.
Duplicate set of genes provides useful functions
The longer the fish has to do without oxygen, the higher the alcohol content in the fish. The blood alcohol rises above 50 mg per 100 milliliters. The researchers said the results show very important factors to better understand evolutionary adaptation. A double set of genes allows them to keep their original shape, but still have a kind of backup set, which can also provide useful functions.
Crucian ability reduces competition in survival with other fish
Ethanol production enables the crucian carp to survive in hostile environments. This ability avoids competition with other fish species that normally live in oxygen-containing waters, explains author Dr. Cathrine Elisabeth Fagernes from the University of Oslo. (as)