Meiotic conductors are a type of selfish gene. Present in the genomes of almost all species, including humans, they unfairly transfer their genetic material to more than half of their offspring, sometimes resulting in infertility and a decrease in the health of the organism. Due to their parasitic potential, their longevity over evolutionary time was considered short-lived, until now.
New research from the Stowers Institute for Medical Research, in collaboration with the National Institute of Biological Sciences in Beijing, China, has discovered a family of selfish genes that have survived for more than 100 million years, or 10 times longer. than any meiotic motor ever identified. casting new doubt on established beliefs about how natural selection and evolution deal with these threatening sequences.
“The thought has always been that because these genes are so nasty, they won’t stick around in populations very long,” said associate researcher Sarah Zanders, Ph.D. , that genomes just can’t always get rid of them.”
Meiotic drivers are so named because they can acquire the ability to literally “drive” the transmission of their genes through a genome, often with negative consequences. Natural selection is therefore the major force that thwarts selfish genes, favoring genetic variants that kill a species’ drive to recover fertility and overall health.
“Natural selection has a limited ability to eliminate meiotic drivers from a population,” Zanders said. “Imagine organizing football team tryouts (natural selection) to recruit the best players (genes that promote fitness). Drivers are players who sabotage other players who try. Drivers make the team, but not because they are good at football.”
In a recent study published in eLife on October 13, 2022, led by researcher Mickael De Carvalho, Ph.D., of Zanders Lab, and Guo-Song Jia, predoctoral researcher in the laboratory of Li-Lin Du, Ph.D., identified for the first time that he family of selfish genes called wtf not only thrived in the fission yeast, Schizosaccharomyces pombe, but was passed on to three unique yeast species that diverged from S. pombe about 119 million years ago.
“This finding is particularly novel because a family of drive genes has thrived at least ten times longer than geneticists ever thought possible,” Zanders said.
During meiosis, the specialized cell division that gives rise to reproductive cells like sperm and eggs, inheritance of genetic material from one set of chromosomes from each parent is 50/50, or equally likely for each cell reproductive.
Yeast meiotic conductors are actually a more powerful genetic parasite. The wtf gene family are killer meiotic drivers; not only do they pass the selfish gene to more than 50% of the offspring, but they then destroy the reproductive cells – or yeast spores – that do not inherit the motor gene.
Natural selection in a genome usually saves a species from selfish genes by favoring genes that suppress or silence driving, rendering it useless. The way the wtf gene family has escaped deletion is largely due to their rapid mutation rates.
This persistence alters our perception of how a species can overcome the expected increase in infertility that typically leads to extinction. It also changes the way scientists can search for and identify selfish gene families in different species, including humans.
“Until now, when looking for candidate drivers within a genome, I wouldn’t have considered ‘old’ genes as a possibility,” Zanders said. “Given that selfish genes are the primary drivers of evolution, this new finding opens the door to thinking about how factors can have persistent, long-term effects on genome evolution.”
The selfish gene acts as both poison and antidote to eliminate competition
Mickaël De Carvalho et al, The wtf meiotic driver gene family has unexpectedly persisted for more than 100 million years, eLife (2022). DOI: 10.7554/eLife.81149
eLife
Provided by the Stowers Institute for Medical Research
Quote: Discovery of 119-million-year-old selfish genes in yeast illustrates the impact of parasitic DNA on genome evolution (October 20, 2022) Retrieved October 21, 2022 from https://phys.org/ news/2022-10-discovery-million-year-old-selfish-genes-yeast.html
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