Updated: February 28, 2020 8:52:48 am
Animals, including humans, need energy to perform the various tasks that are essential for survival. Aerobic respiration is one such chemical reaction through which organisms take in oxygen and release carbon dioxide into the atmosphere. Through this mechanism, energy is transferred to cells, which can use it for multiple purposes — for instance, to burn food.
Now, researchers at Tel Aviv University (TAU) have discovered a non-oxygen breathing animal, which significantly changes one of science’s assumptions about the animal world — that all animals use aerobic respiration and therefore, oxygen.
It also challenges what may be generally thought of as evolution in organisms — that they become more complex as they evolve. In the case of this non-oxygen breathing organism, evolution turned it into a simpler organism that shed “unnecessary genes” responsible for aerobic respiration.
The organism is Henneguya salminicola, a fewer-than-10-celled microscopic parasite that lives in salmon muscle. According to the researchers, as the organism evolved, it gave up breathing and stopped the consumption of oxygen for the production of energy — which means it relies on anaerobic respiration (through which cells extract energy without using oxygen).
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Other organisms such as fungi and amoebas that are found in anaerobic environments lost the ability to breathe over time. The new study shows that the same can happen in the case of animals, too.
That the parasite does not require oxygen was discovered by accident while assembling its genome sequence. One of the researchers saw that it did not have a mitochondrial genome. Mitochondria is the “powerhouse” of the cell, which captures oxygen to make energy — its absence in the H. salminicola genome indicates that the parasite does not breathe oxygen. (‘A cnidarian parasite of salmon (Myxozoa: Henneguya) lacks a mitochondrial genome’, Yahalomi et. al: Proceedings of the National Academy of Sciences, February 24, 2020)
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