'Cheater mitochondria' may profit from cellular stress coping mechanisms


Date:
September 22, 2020
Source:
eLife
Summary:
Cheating mitochondria may take advantage of cellular mechanisms
for coping with food scarcity in a simple worm to persist, even
though this can reduce the worm's wellbeing.



FULL STORY ========================================================================== Cheating mitochondria may take advantage of cellular mechanisms for
coping with food scarcity in a simple worm to persist, even though this
can reduce the worm's wellbeing.


========================================================================== These findings, published today in eLife, may help shed light on the
evolution of cheating and cooperative behaviours within different
organisms.

Mitochondria are energy-producing units within cells that likely evolved
from bacteria. They have their own DNA, take in resources from cells,
and in exchange provide the cell with energy. But some so-called 'cheater mitochondria' have harmful DNA mutations that may reduce their energy
output and harm the organism. Why these cheater mitochondria persist
despite their harm to the larger organism is not currently clear.

"Cooperation and cheating are widespread evolutionary strategies,"
says lead author Bryan Gitschlag, a PhD student at the Department of
Biological Sciences, Vanderbilt University, Nashville, Tennessee. "While cheating confers an advantage to individual entities within a group, competition between groups favours cooperation." Gitschlag and his
colleagues studied the roundworm Caenorhabiditis elegans to see how
competing evolutionary pressures within its cells and in its environment
might enable the cheater mitochondria to persist.

They measured the levels of cheater and typical mitochondria in the worm's cells. They found that, within the cells, a protein called DAF-16, which
helps cells to survive stress, is necessary for cheater mitochondria
to multiply.

When the worms face food shortages, cheater mitochondria become more
harmful to their hosts, but only in those lacking DAF-16. "This shows
that food scarcity can strengthen evolutionary selection against worms
carrying cheater mitochondria, but DAF-16 protects them from it,"
Gitschlag explains.

The results suggest that competing selection pressures within an organism
and in its environment may shed light on why selfishness and cooperation
often exist side-by-side among populations.

"The ability to cope with scarcity can promote group-level tolerance to cheating, inadvertently prolonging cheater persistence," says senior
author Maulik Patel, Assistant Professor of Biological Sciences at
Vanderbilt University.

"As selfish mitochondrial genomes are implicated in numerous disorders,
and cheating is a widespread evolutionary strategy, it will be interesting
to apply our methods to study a broader collection of cheating variants
and host species. This could allow us to better understand the development
of mitochondrial disorders or the evolutionary principles underlying cooperation and cheating," Patel concludes.


========================================================================== Story Source: Materials provided by eLife. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Bryan L Gitschlag, Ann T Tate, Maulik R Patel. Nutrient status
shapes
selfish mitochondrial genome dynamics across different levels of
selection. eLife, 2020; 9 DOI: 10.7554/eLife.56686 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200922135732.htm

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