Essential Science: Should we worry about gene extinction?

Posted Sep 5, 2016 by Tim Sandle
A consortium of scientists has expressed concern about ‘gene extinction’ technology (or 'gene drives'), claiming it could lead to species loss. Digital Journal examines this controversial field.
CRISPR -  revolutionary new tool to cut and splice DNA.
CRISPR - revolutionary new tool to cut and splice DNA.
Illustration courtesy of Jennifer Doudna/UC Berkeley
Stemming from the 2016 World Conservation Congress a number of scientists and environmentalists have expressed concerns about the use of so-called ‘gene drives.’ This refers to a new synthetic biology technology. The technology has the potential to push a targeted species to extinction.
An alternative name for gene drive is ‘mutagenic chain reactions.’ The essential aim is to DNA so an organism always passes down a desired trait, hoping to change over time the genetic makeup of an entire species. This could be, by affecting the females in a population, an attempt to stop a species from breeding, pushing it towards extinction.
This is further explained by SynBiowatch:
A trait is a genetically determined characteristic of an organism (e.g. eye color). In normal sexual reproduction, a trait generally has only a 50% chance of being expressed. With a gene drive, however, that trait is “driven” into the organism’s reproductive cycle so that every single offspring always carries and expresses the specified trait.
An alternative view, outlining the potential benefits, is provided by the Wyss Institute in the following video:
One of the methods involved is CRISPR, which is an acronym for “Clustered regularly-interspaced short palindromic repeats.” This is a relatively new genome editing tool that functions like molecular scissors. The method allows scientists to modify an organism’s DNA. Using a Cas9 protein and appropriate guide, genetic material can be easily delivered into a cell in any desired location.
The chilling phrase  extinction  warns those taking part in Generation of Z.
The chilling phrase 'extinction' warns those taking part in Generation of Z.
Driving a dangerous species to extinction (as in one that poses a risk to human health) may seem like a ‘good idea’ to some, the act of doing so will have consequences and will affect the wider environment and species food chains. Many scientists are concerned about the overall impact on biodiversity.
Others are concerned that the technology could move from addressing pathogen risks to modifying agriculture, or even being used to military purposes as a bio-weapon.
Examples of ‘gene drives’ include releasing gene drive mice on the South Farallon Islands to eradicate the mouse population, through the modified mice being unable to breed. There is an acknowledged problem on the islands. The common house mouse (Mus musculus) has substantially disrupted the island ecosystem. This is through spreading the seeds of invasive plants, eating the endemic camel cricket and a type of daisy called maritime goldfields. The flower provides critical nesting material for birds. However, the matte is whether a gene drive is the best means to address the mouse problem.
A second example is with gene drive mosquitoes to combat avian malaria (a disease of honeycreeper birds). Similarly, as a consequence of the Zika virus threat, a British-based biotechnology company has carried out tests on a genetically modified Aedes aegypti mosquito, designed to try to stop transmission of the viral disease.
Commenting on the principle Luke Alphey, who works to control disease-spreading insects using other genetic techniques, questioned the ethics of wiping out an entire species: “Humans have undoubtedly driven a very large number of species to extinction, but we’ve only deliberately done it with two: smallpox and rinderpest,” he said. “Would we want to do that with Anopheles gambiae?”
At the World Conservation Congress, the International Union for the Conservation of Nature (IUCN) voted to adopt a de facto moratorium on supporting research into gene drives for conservation until a full impact assessment has been performed. Those backing the ban included well known scientists like Dr. Jane Goodall and Dr. David Suzuki.
In an open letter the scientists write: “Gene drives, which have not been tested for unintended consequences, nor fully evaluated for ethical and social impacts, should not be promoted as conservation tools.”
The gene driver issue will have supporters and opponents in equal measure. It is an example of where science and public policy need to resolve issues of disease control and environmental protection, and to put forward a robust framework to control how this technology is used in the future.
This article is part of Digital Journal's regular Essential Science columns. Each week we explore a topical and important scientific issue. Last week we saw how a new Parkinson's protein test could lead to earlier diagnosis of the disease. The week before we looked at how electroconvulsive shock treatment is making a come-back.