Nav: Home

Safely releasing genetically modified genes into the wild

August 01, 2017

So, you've genetically engineered a malaria-resistant mosquito, now what? How many mosquitos would you need to replace the disease-carrying wild type? What is the most effective distribution pattern? How could you stop a premature release of the engineered mosquitos?

Releasing genetically engineered organisms into an environment without knowing the answers to these questions could cause irreversible damage to the ecosystem. But how do you answer these questions without field experiments?

Applied mathematicians and physicists from Harvard and Princeton Universities used mathematical modeling to guide the design and distribution of genetically modified genes that can both effectively replace wild mosquitos and be safely controlled.

The research was recently published in the Proceedings of the National Academy of Sciences.

In the normal course of evolution, any specific trait has only a modest chance of being inherited by offspring. But, with the development of the CRISPR-Cas9 gene editing system, researchers can now design systems that increase the likelihood of inheritance of a desired trait to nearly 100 percent, even if that trait confers a selective disadvantage. These so-called gene drives could replace wild-type genes in short generations.

Those powerful systems raise serious safety concerns, such as what happens if a genetically-engineered mosquito accidentally escapes from a lab?

"An accidental or premature release of a gene drive construct to the natural environment could damage an ecosystem irreversibly," said Hidenori Tanaka, first author of the paper and graduate student in the Harvard John A. Paulson School of Engineering and Applied Sciences and the Physics Department.

To protect against such releases, Tanaka, along with co-authors David Nelson, the Arthur K. Solomon Professor of Biophysics and Professor of Physics and Applied Physics and Howard Stone of Princeton, proposed a narrow range of selective disadvantages that would allow the genes to spread, but only after a critical threshold had been reached.

The researchers used nonlinear reaction-diffusion equations to model how genes would move through space. These models provided a framework to develop socially responsible gene drives that balance the genetically-engineered traits with embedded weaknesses that would protect against accidental release and uncontrollable spreading.

"We can, in effect, construct switches that initiate and terminate the gene drive wave," said Tanaka. "In one, carefully chosen regime, the spatial spreading of the wave starts or progresses only when the parameters of the inoculation exceed critical values that we can calculate."

To reach that critical mass, the researchers found that genes needed to be released intensely in a specific region -- like a genetic bomb -- rather than spread thinly throughout larger regions. The genes spread only when the nucleus of the genetic explosion exceeds a critical size and intensity.

The researchers also found that by making gene drives susceptible to a compound harmless to wildtype genes, the spread of gene drives can be stopped by barriers like pesticides.

"This research illustrates how physicists and applied mathematicians can build on results of biological experimentation and theory to contribute to the growing field of spatial population genetics," said Nelson.

Next, the researchers hope to understand the impact of genetic mutations and organism number fluctuations on gene drives.
-end-
The paper was coauthored by Howard Stone, the Donald R. Dixon '69 and Elizabeth W. Dixon Professor of Mechanical and Aerospace Engineering and Department Chair at Princeton University.

This research was supported by the National Science Foundation through the Division of Materials Research, Condensed Matter and Materials Theory and through the Harvard Materials Science Research and Engineering Center.

Harvard John A. Paulson School of Engineering and Applied Sciences

Related Genes Articles:

Insomnia genes found
An international team of researchers has found, for the first time, seven risk genes for insomnia.
Genes affecting our communication skills relate to genes for psychiatric disorder
By screening thousands of individuals, an international team led by researchers of the Max Planck Institute for Psycholinguistics, the University of Bristol, the Broad Institute and the iPSYCH consortium has provided new insights into the relationship between genes that confer risk for autism or schizophrenia and genes that influence our ability to communicate during the course of development.
The fate of Neanderthal genes
The Neanderthals disappeared about 30,000 years ago, but little pieces of them live on in the form of DNA sequences scattered through the modern human genome.
Face shape is in the genes
Many of the characteristics that make up a person's face, such as nose size and face width, stem from specific genetic variations, reports John Shaffer of the University of Pittsburgh in Pennsylvania, and colleagues, in a study published on Aug.
Study finds hundreds of genes and genetic codes that regulate genes tied to alcoholism
Using rats carefully bred to either drink large amounts of alcohol or to spurn it, researchers at Indiana and Purdue universities have identified hundreds of genes that appear to play a role in increasing the desire to drink alcohol.
Reading between the genes
For a long time dismissed as 'junk DNA,' we now know that also the regions between the genes fulfill vital functions.
The silence of the genes
Research led by Dr. Keiji Tanimoto from the University of Tsukuba, Japan, has brought us closer to understanding the mechanisms underlying the phenomenon of genomic imprinting.
Why some genes are highly expressed
The DNA in our cells is folded into millions of small packets, like beads on a string, allowing our two-meter linear DNA genomes to fit into a nucleus of only about 0.01 mm in diameter.
Activating genes on demand
A new approach developed by Harvard geneticist George Church, Ph.D., can help uncover how tandem gene circuits dictate life processes, such as the healthy development of tissue or the triggering of a particular disease, and can also be used for directing precision stem cell differentiation for regenerative medicine and growing organ transplants.
Controlling genes with light
Researchers at Duke University have demonstrated a new way to activate genes with light, allowing precisely controlled and targeted genetic studies and applications.

Related Genes Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Anthropomorphic
Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#SB2 2019 Science Birthday Minisode: Mary Golda Ross
Our second annual Science Birthday is here, and this year we celebrate the wonderful Mary Golda Ross, born 9 August 1908. She died in 2008 at age 99, but left a lasting mark on the science of rocketry and space exploration as an early woman in engineering, and one of the first Native Americans in engineering. Join Rachelle and Bethany for this very special birthday minisode celebrating Mary and her achievements. Thanks to our Patreons who make this show possible! Read more about Mary G. Ross: Interview with Mary Ross on Lash Publications International, by Laurel Sheppard Meet Mary Golda...