A strange microbe was able to survive despite the lack of mitochondria — the powerhouse of the cell.
Mitochondria are components enveloped in a membrane that are found in cells. These substances are critical for the life and function of organisms called eukaryotes such as plants, animals and fungi among others.
Eukaryotes are those that contain cells that have DNA in the form of chromosomes. All living organisms, except some forms of bacteria, are considered eukaryotes.
Study author Anna Karnkowska explains that in areas with low oxygen, eukaryotes frequently have a reduced type of mitochondrion. However, because the functions of these cell powerhouses are so critical, they are believed to be fundamental for life.
The new study challenges that notion and instead suggests that it is possible for eukaryotes to survive without the mitochondria.
"We have characterized a eukaryotic microbe which indeed possesses no mitochondrion at all," says Karnkowska.
The research team used organisms from the genus Monocercomonoides, which are related to more popular pathogens such as Trichomonas and Giardia. All of these organisms are under a classification called Metamonada, which settles solely in environments with low oxygen.
When the researchers sequenced Monocercomonoides, they were surprised to discover that the organisms do not have mitochondrial proteins.
The organism appears to have survived even without its powerhouse component due to cytosolic sulfur mobilization system (SUF) — a substance that had been acquired from bacteria that have similar mitochondrial properties. Through this, along with other events, the organism has evolved far beyond what biologists previously marked off.
Ending Researchers' Quest
For decades, experts have been searching for organisms that do not have mitochondria. Years passed, yet scientists remained unsuccessful in their quest. That made them think that it may be truly impossible for eukaryotes to lack mitochondria.
The new study was finally able to refute this belief. Karnkowska even describes it as a striking example of a cell that is successful in delineating from the writings of standard textbooks. She adds that the team believes there may be more similar samples tucked somewhere in the world.
Future plans include learning more about how these organisms function, and characterizing the organism and its relatives to better comprehend their discovery in a broader context.
The study was published in the Cell Press journal Current Biology on May 12.