Salmon Fish's Parasite Survives Without Oxygen

Salmon fish contains a jellyfish-like parasite, Henneguya salminicola. According to researchers, this parasite can survive without oxygen. This parasite does no have mitochondria too.  

Many of the current and age-old systems of the Universe always been undeniable until we see an exception on any facts. Every molecular life can not live without oxygen is like a universal truth. But not anymore. A recent study report by scientists makes us rethink the fact again.

The discovery is unique as the parasite the research focuses on does not have any mitochondrial genome. The parasite looks like a jellyfish. This is the first multicellular organism without that genome. As a result, it does not need oxygen to breathe. Instead, it never entirely depends on oxygen throughout its life.  

This discovery can lead the scientists the way of finding out not only how life works on earth without oxygen but also search for extraterrestrial life by further researching.

More than 1.45 billion years ago, life started being dependant on oxygen metabolism for respiratory purposes. At that time, a smaller bacterium got engulfed by a larger archaeon. The bacterium loved the new home, and the two groups got benefits from each other. So, they stayed together. 

The relationship between the two grew healthier and healthier. Later, that very bacterium turned into organelles that we know today as mitochondria. Mitochondria is abundant in every cell in our body, although red blood cell is an exception. Mitochondria is a must for running respiratory operations.     

Mitochondria are known as the powerhouse of cells. They power the cells by producing adenosine triphosphate after breaking down oxygen. 

There are some organisms which can survive in low-oxygen, or hypoxic, conditions by using their adaptations processes. Anaerobic metabolism has been a subject of debate for the scientists for long. It is a process of evolving mitochondria-related organelles by some organisms with a single cell.

But recent research changed our early thoughts. Dayana Yahalomi and the team from Tel Aviv University, Israel, made this discovery while looking a bit deeper on Henneguya salminicola, a common salmon parasite. 

This parasite is like a friend to salmon and other phyla like corals, anemones, and jellyfish. This parasite is capable of creating cysts in fish' flesh that is a bit ugly, but they are not harmful at all. They share the same journey with the salmons' life cycle and never leave its host.

Always living inside the host, it needs to face hypoxic conditions and survive within the host. But how they do that is a question, and researchers need to examine the creature's DNA to understand how. This is the primary purpose of the research.

While doing this, they used fluorescence microscopy and deep sequencing to have a more in-depth look. The team was surprised to see that there is no presence of the mitochondrial genome. As a result, aerobic respiration was also lost. All the mitochondria-related nuclear genes gone. 

Though it has evolved mitochondria-related organelles like other single-celled organisms, they are not similar to others'. In the inner membrane of the mitochondria-related organelles of H. salminicola, the team saw folds that are also unusual.

When the team applied the same processes on Myxobolus squamalis, another fish parasite, they found the presence of the mitochondrial genome.

As a final decision, the team concluded that they had found a multicellular organism surviving without being dependant on oxygen. 

How they survive without oxygen is still a mystery, and further research is required to determine it.

Another surprising fact that the simple-looking parasite was once a free-living jellyfish. Over the long-term period, they have become tinier and living within the salmon fish.

Although they have lost many of the original jellyfish genomes, still some of them remain. The odd one is that it resembles jellyfish stinging cells. They do not use these cells to prick but use them to stay connected with the host. 

This discovery can help the fisheries to establish new techniques to deal with this parasite, although they are not harmful to humans.

The most important aspect of this discovery is that it helps us to understand how life works.

Researchers published the report in PNAS. They say, "Our discovery confirms that adaptation to an anaerobic environment is not unique to single-celled eukaryotes, but has also evolved in a multicellular, parasitic animal. Hence, H. salminicola provides an opportunity for understanding the evolutionary transition from anaerobic to an exclusive anaerobic metabolism."