It is well known that oxygen is a necessary condition for living by living things. Plants, animals and microorganisms in nature are commonly breathing. Breathing oxygen is considered a basic feature of multicellular animals, but nothing is absolute, and nature can always bring us some surprises.
Israeli scientists have found that a parasite called the salmon-tailed spore does not need to breathe oxygen to get energy, and they have confirmed that the salmon-tailed spores do not have mitochondrial genomes in their bodies and therefore cannot breathe. It is also the first known non-breathing animal on Earth.
Mitochondrial genomes are small but vital parts of DNA in animal mitochondria, including genes responsible for respiratory action. Salmon-tailed spores are a parasite that infects salmon. A team led by Dorothy Hosson of Tel Aviv University microscopeed and genome-analysing the salmon-tailed spore and found that, unlike all other known animals, the parasite had no mitochondrial genome. In addition, the study, co-authored by Atkinson, a senior associate researcher in the Department of Microbiology at Oregon State University, also found that less than 10 cells of “salmon tail spores” are jellyfish-like and coral-like mucosa, and are common salmon parasites. They adapt to the near-oxygen-free environment in salmon because the salmon tail spores do not have a mitochondrial genome. The mitochondrial experience converts food into energy, and without the mitochondrial genome, it doesn’t have to replicate the useless genes that energy can be stored.
In our understanding, animals are generally multicellular organisms with many genes that have evolved more and more complexly. When viewed under a microscope, the spores of the “salmon-tailed spores” look like blue sperm cells, with two tails and an oval pair of alien-like eyes. Cells that resemble “eyes” are actually stingcells, which can help parasites attach to their hosts when needed, one of the characteristics that the “salmon-tailed spores” did not give up during their evolution, but the hedgehogcells do not contain venom. Through research, the salmon-tailed spore loses its ability to breathe if it loses tissue, nerve cells, muscles, and so on. This gene atrophy may be a good thing for the parasite, which allows it to reproduce as quickly and frequently as possible.
At present, how the “salmon tail spore” can obtain the required energy without breathing remains a mystery. Experts have speculated that perhaps the “salmon-tailed spore” may have obtained oxygen from salmon cells, or that it may have evolved a survival method similar to that of a single-celled organism, or that it is attached to a host of energy that has been created to sustain life by absorbing the host’s molecules. But these inferences are all guesses, and the answer needs to be further studied to determine.
This paper is carried out by Huang Shaohua, a senior teacher of the second middle school in Chaisan District, Jiujiang City.