Salmon Parasite Is First Animal Known To Not Breathe Oxygen |BEST|
The discovery was initially made by Tel Aviv University's Prof. Dorothee Huchon, when she realized that a microscopic fish parasite known as Henneguya salminicola lacked a mitochondrial genome. Found in large numbers in most cells, the mitochondria are organelles that capture oxygen in order to produce energy. Because these are lacking in the parasite, Huchon and colleagues determined that it must not be an oxygen-breather.
Salmon parasite is first animal known to not breathe oxygen
That said, it still isn't clear how the parasite does make do. The researchers believe that it may draw energy from the surrounding salmon cells, or that it might utilize a different type of respiration such as oxygen-free breathing. In any case, the discovery has definitely caused the scientists to rethink some things.
An unusual species of parasite was recently discovered by scientists. The tiny parasite hides in the muscles of salmon and has less than 10 cells. And most peculiar, the species, Henneguya salminicola, does not breathe oxygen. This abnormal trait makes it the first known multicellular animal that can survive without oxygen.
While H. salminicola is the first animal to lose ability over time, it is not the first organism to lose the ability. Other organisms, such as fungi, amoebas or ciliate lineages, have also lost the ability to breathe over time. However, the recent study demonstrates that this same process can happen to an animal.
While conducting research, the scientists found that the mitochondrial genome was missing from the animal. Mitochondria are fundamental for collecting oxygen and converting it into energy. Thus, scientists concluded that the tiny parasite no longer breathes oxygen.
Researchers have discovered an animal lacking a mitochondria and many of the genes that facilitate aerobic respiration. The animal is a salmon parasite called Henneguya salminicola, and it is a member of the phylum Cnidaria, which also contains jellyfish and sea anemones. The international team of researchers published a study with their results on Monday in the journal PNAS.
Because the parasite is without mitochondria, scientists determined Henneguya salminicola no longer breathes oxygen. The parasite -- described this week in the journal PNAS -- provides proof that animals can survive anaerobic environments.Advertisement
The first large and diverse group of complex, multicellular life forms emerged around the time that oxygen levels on Earth rose dramatically. Scientists have long assumed that aerobic respiration is ubiquitous in the animal kingdom.RELATED One billion-year-old green seaweed fossils unearthed in China
"It's not yet clear to us how the parasite generates energy," Huchon said. "It may be drawing it from the surrounding fish cells, or it may have a different type of respiration such as oxygen-free breathing, which typically characterizes anaerobic non-animal organisms."
Scientists have just discovered that a jellyfish-like parasite doesn't have a mitochondrial genome - the first multicellular organism known to have this absence. That means it doesn't breathe; in fact, it lives its life completely free of oxygen dependency.
The tiny, less than 10-celled parasite Henneguya salminicola lives in salmon muscle. As it evolved, the animal, which is a myxozoan relative of jellyfish and corals, gave up breathing and consuming oxygen to produce energy.
Some other organisms like fungi, amoebas or ciliate lineages in anaerobic environments have lost the ability to breathe over time. The new study demonstrates that the same can happen to an animal -- possibly because the parasite happens to live in an anaerobic environment.
The parasite's anaerobic nature was an accidental discovery. While assembling the Henneguya genome, Prof. Huchon found that it did not include a mitochondrial genome. The mitochondria is the powerhouse of the cell where oxygen is captured to make energy, so its absence indicated that the animal was not breathing oxygen.
Until the new discovery, there was debate regarding the possibility that organisms belonging to the animal kingdom could survive in anaerobic environments. The assumption that all animals are breathing oxygen was based, among other things, on the fact that animals are multicellular, highly developed organisms, which first appeared on Earth when oxygen levels rose.
"It's not yet clear to us how the parasite generates energy," Prof. Huchon says. "It may be drawing it from the surrounding fish cells, or it may have a different type of respiration such as oxygen-free breathing, which typically characterizes anaerobic non-animal organisms."
But, this is not accurate. Many known animals do not breathe, but this is the first known animal to not use aerobic respiration. However, these inaccurate headlines do allow for a very teachable biology moment!
However, unlike almost every other animal we know, this new parasite does not use respiration to live. In other words, it has evolved to survive completely without oxygen. That, frankly, is quite amazing.
Huchon and a team of international researchers examined and sequenced all of H. salminicola's genes in their study, published Monday in the journal Proceedings of the National Academy of Sciences. They found that the parasite, which is closely related to jellyfish, lacks the DNA machinery necessary to "breathe" -- it doesn't have mitochondria, often called the "powerhouse" of the cell, because they use oxygen to make energy. It's like a little factory inside (almost) all cells, and DNA sleuths can find mitochondrial genes during sequencing.
The newly discovered parasite, known as Henneguya salminicola, is comprised of fewer than 10 cells and lives inside salmon muscle. The animal, which is classed as a myxozoan, is thought to be a relative of jellyfish and coral.
This is the first macroscopic creature known to not breathe oxygen. This simple trait has been with macroscopic life as we know it, ever since an Archaea swallowed a smaller bacterium, and somehow this worked out for both parties and the two stayed together. That is, the smaller bacteria became an organelle called mitochondria (the fabled powerhouse of the cell), an essential part of the breathing process.
The assumption that all animals are breathing oxygen was based, among other things, on the fact that animals are multicellular, highly developed organisms, which first appeared on Earth when oxygen levels rose.
The common concept that all organisms need oxygen to live might be wrong as researchers discovered a unique organism that does not need to breathe to survive. This jellyfish-like parasite is the first multicellular organism known that does not have a mitochondrial genome, therefore, living its life without depending on oxygen.
This tiny parasite survived in salmon tissue and evolved so that it does not need oxygen to produce energy. It is a great simplification that sometimes less is more, according to Stephen Atkinson, a senior research associate at the Department of Microbiology at Oregon State University.
This parasite is a cnidarian, which belongs to the same phylum as the corals, jellyfish, and anemones. They live their entire life cycle inside the salmon and steals ready-made nutrients instead of consuming oxygen on its own, and they are not harmful to humans even though they create unsightly cysts in the salmon's flesh.
They can survive hypoxic environments inside its host, which baffled scientists. Atkinson, who co-authored the paper, said that when thinking about animals we picture a multicellular organism that requires oxygen to survive, but with the case of the parasite, there is at least one multicellular animal that does not have the genetic toolkit to use oxygen.
Henneguya salminicola is the only known multicellular animal that does not rely on the aerobic respiration of oxygen. It lacks a mitochondrial genome and therefore mitochondria, making it one of the only members of the eukaryotic animal kingdom to shun oxygen as the foundation of its metabolism. The means by which H. zschokkei utilizes chemical energy for the sustenance of its life is not yet known.
Scientists have studied H. salminicola, with the help of deep sequencing and fluorescence microscopy and found the absence of mitochondrial genome and lack of nuclear genes associated with transcribing and replicating mitochondria. As a control setup, a similar study was conducted on a closely related cnidarian fish parasite, namely, Myxobolus squamalis. The control group revealed the presence of a mitochondrial genome. This further confirms that H. salminicola does not require oxygen to survive. The exact survival mechanism is still unknown; however, it is possible that they extract ATP from the host.
The assumption that all animals are breathing oxygen was based, among other things, on the fact that animals are multicellular, highly developed organisms, which first appeared on the Earth when oxygen levels rose, they said.
A team of scientists at the Tel Aviv University in Israel have found life-form that can survive without oxygen. The team led by Dayana Yahalomi took a closer look at the DNA of the jellyfish-like parasite in salmon called Henneguya salminicola.
Some lower single-celled organisms or eukaryotes are able to respire without oxygen with a process known as anaerobic respiration. But no previous case of higher organisms like animals and plants doing the same had been found.
Mitochondrial respiration is an ancient characteristic of eukaryotes. However, it was lost independently in multiple eukaryotic lineages as part of adaptations to an anaerobic lifestyle. An international team of researchers has found a multicellular animal with no mitochondrial DNA, making it the only known animal to exist without the need to breathe oxygen. In their paper published in Proceedings of the National Academy of Sciences , the group describes their study of Henneguya salminicola, a microscopic, parasitic member of the group Myxozoa and its unique physiology. 350c69d7ab