NOV 03, 2018 8:04 AM PDT

Stopping a Jumping Gene Invasion

WRITTEN BY: Carmen Leitch

Researchers at the Carnegie Institution have been researching genetic features called transposons or jumping genes since Barbara McClintock discovered them, which got her the Nobel Prize in 1983. Since then, scientists have found that they comprise around 44 percent of our DNA (though it does not seem these areas are all active). They can disrupt the genome significantly as they insert themselves within the genomes of egg or sperm cells, and can cause death depending on where they land. It’s thought that organisms have tolerated huge numbers of genetic invasions by these damaging elements over many generations. New research has indicated that stem cells react to the changes transposons induce.

Ovaries after jumping gene invasion, DNA damage checkpoint pause, and repair  / Credit: Zhao Zheng Carnegie Institution

Carnegie scientists found that when stem cells sense transposon activity, they increase the levels of a non-coding genetic material, piRNA (piwi-interacting RNA). That acts to suppress the activity of jumping genes and initiates a DNA repair mechanism; egg cells can then develop normally. These findings, which show how organisms may have survived many rounds of jumping gene invasions, have been reported in Developmental Cell.

The investigators used a common genetic research model, the fruit fly, for this work. It’s been established that temperature influences the sperm and egg cells of fruit flies. When it’s 77 degrees Fahrenheit, fruit fly offspring have sterile ovaries. At a temperature of 64 degrees Fahrenheit, ovaries are fertile and normally developed. Temperature also influenced the severity of the jumping gene effect.

"Because temperature had been widely known to affect sterility, we decided to quantify the rates of this jumping gene's activity at different temperatures. We discovered that the rate of jumping gene mobilization was seven times greater at 77 degrees F in ovarian stem cells, which means we can simply use temperature to control the invasion intensity from jumping genes," explained the first author of the report, Sungjin Moon.

The team was used the adult fly ovary to model the effect of jumping genes. They found that reproductive stem cells can respond to invading genetic elements by starting up a DNA damage checkpoint. Damaged DNA can then be fixed before cells divide and incorporate the damage. One component, Chk2, was found to be a critical part of the process.

DNA repair pauses while piRNA production is ramped up, so the jumping genes can be stopped. The researchers determined that the pause is essential; it can permanently silence the transposons. Normal egg production was found to resume within four days.

Image credit: Pixabay

"Jumping gene invasion triggers catastrophic genomic instability in all organisms," added Zhao Zhang. "They greatly reduce the viability or fertility of the invaded animals and can lead to a population crisis. We believe that the ability of reproductive stem cells to rapidly adapt and restore fertility in this manner allows species to resist such a population crash. This mechanism is a lynchpin to species survival."


Sources: AAAS/Eurekalert! via Carnegie Institution for Science, Trends in GeneticsDevelopmental Cell

About the Author
  • Experienced research scientist and technical expert with authorships on 28 peer-reviewed publications, traveler to over 60 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
APR 21, 2020
Cell & Molecular Biology
Virtual Cell Provides a Close Look at Gene Expression During Development
APR 21, 2020
Virtual Cell Provides a Close Look at Gene Expression During Development
Living organisms start out as one cell, and its genetic programs allow it to divide many times over, to give rise to the ...
APR 25, 2020
Neuroscience
Autoimmune Protein May Cause OCD
APR 25, 2020
Autoimmune Protein May Cause OCD
Researchers from Queen Mary University in London have discovered a specific autoimmune protein that may cause OCD-relate ...
MAY 25, 2020
Genetics & Genomics
FDA Approves the First Treatment for Neurofibromatosis 1
MAY 25, 2020
FDA Approves the First Treatment for Neurofibromatosis 1
In a major breakthrough, the Food and Drug Administration has approved a treatment for a genetic disorder called neurofi ...
JUN 22, 2020
Cell & Molecular Biology
Viruses Can Create New Genes By Stealing Bits of Human DNA
JUN 22, 2020
Viruses Can Create New Genes By Stealing Bits of Human DNA
When viruses infect cells, they hijack the machinery inside and start to use it for their own purposes. This enables vir ...
JUL 14, 2020
Genetics & Genomics
The Human X Chromosome is Sequenced From End to End
JUL 14, 2020
The Human X Chromosome is Sequenced From End to End
In a major milestone, scientists have completed the first sequence of a human chromosome that reaches from one end to th ...
AUG 05, 2020
Genetics & Genomics
Bullock's & Baltimore Orioles May Mix, But They Won't Merge
AUG 05, 2020
Bullock's & Baltimore Orioles May Mix, But They Won't Merge
Researchers have data that can finally settle a long controversy in the birding world.
Loading Comments...