By Tiffany Lu
Invasive species are non-native organisms that disrupt local ecosystems and have been an environmental challenge for centuries. These species can cause significant ecological damage, leading to the decline or extinction of native plants and animals. While there are methods of control, such as chemical pesticides and habitat alteration, these often have limitations and can inadvertently harm other species. However, CRISPR-based gene drives offer a different approach to address this challenge.
CRISPR-based gene drives are a technology that uses genetic engineering to combat invasive species. This technology uses the CRISPR-Cas9 system to allow scientists to target and modify specific genes within invasive species. CRISPR contains unique DNA sequences that serve as a guide for the Cas9 enzyme to target specific genes in an organism. Once the CRISPR-Cas9 system is introduced into the invasive species, Cas9 acts as scissors, cutting the targeted DNA sequences. This initiates the DNA repair process of the organism. Scientists introduce a modified DNA template alongside the CRISPR system, which can serve as a replacement for the original DNA sequence and is often incorporated into the organism’s genome.
This enables scientists to alter the genetic makeup of a population. Unlike traditional genetic engineering, gene drives ensure that a specific trait is inherited by nearly all offspring, rapidly spreading that trait through the population, which can lead to a decrease in the number of invasive species and their potential for harm. Traditional inheritance follows Mendelian inheritance: genes have a 50% chance of being passed on. However, gene drives disrupt this pattern by promoting the inheritance of the modified gene.
One of the techniques is underdominance, which is when the modified gene is engineered to be less fit than the natural version in the invasive species. Over time, the gene drive can spread the less fit version through the population, gradually reducing the overall fitness of the invasive species, and allowing the population to decline. CRISPR-based gene drives can also be used to suppress the populations of invasive species over time by reducing their fitness or reproductive abilities by introducing genetic modifications. This is a more sustainable approach in comparison to ongoing management efforts.
Additionally, gene drives can be designed in a way that makes them reversible. Scientists have developed several drives to counteract the spread of the engineered gene once it has fulfilled its objectives. This approach adds more control and safety by making it possible to stop the gene drive’s effects in case there are consequences or environmental conditions that occur.
The potential applications of CRISPR-based gene drives in invasive species control are diverse. For example, gene drives can reduce the population of disease-carry mosquitoes, such as the Aedes aegypti, which transmits diseases like Zika, dengue, and malaria. Moreover, invasive plant species like kudzu or water hyacinth can be targeted to prevent them from outcompeting native vegetation. However, it is important to note that the success of gene drives in invasive species can be influenced by factors such as the reproductive rate and population size of the target species, genetic diversity, and ecological interactions.
CRISPR-based gene drives also raise important ethical and environmental concerns that we should keep in mind. Unintended consequences such as the accidental modification of a non-target species are a concern. Research into CRISPR-based gene drives is ongoing, with scientists constantly working to improve the precision and safety of the technology by developing regulations to ensure the responsible use of technology.
Art Credits:
ART-ur/Shutterstock.com
Bibliography:
https://elifesciences.org/articles/03401
https://nap.nationalacademies.org/read/23405/chapter/1#v
https://www.pnas.org/doi/full/10.1073/pnas.1514258112
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