Researchers discover organism that doesn't need to breathe to survive

Researchers have discovered an organism that does not need to breathe to survive.

An 8-millimeter parasite that affects Chinook salmon, called Henneguya salminicola, survives without breathing oxygen, according to the study published Feb. 24 in the Proceedings of the National Academy of Sciences of the United States of America.

"Our discovery shows that aerobic respiration, one of the most important metabolic pathways, is not ubiquitous among animals," the researchers said.

When they first sequenced the parasite’s genome and found no sign of mitochondrial DNA the researchers thought they had made a mistake. However, after resequencing there was still no sign of mitochondrial DNA. This caused them to take a closer look at the rest of the parasite’s genome.

What they realized was that the instructions to make the mitochondrial DNA polymerase contained several mutations and the gene was not expressed.  This means the machinery to replicate mitochondrial DNA in this parasite was broken.  This finding made sense given their discovery that the parasite does not have mitochondrial DNA.  What is not clear is which happened first the loss of mtDNA or the accumulation of mutations in the polymerase.  But in either case this parasite does not breathe oxygen.

The Tel Aviv researchers theorize that in order to survive, H. salminicola steal energy from the host salmon they burrow into, using proteins of some sort, in order to create the fuel they need.

This research highlights that organisms may lose genetic information as they fill a particular niche. “The myxozoa represent an extreme example of degeneration of body plans due to parasitism,” a previous study concluded. “Genome and transcriptome analyses reveal that this degeneration was accompanied by massive genome reduction, with myxozoans having one of the smallest reported animal genomes.”

Future studies may explore how parasite relationships allow for significant loss of genetic information and the competitive advantages it affords to an organism.