Predator Free 2050 (PF2050) is a New Zealand Government enforced plan with the goal to eradicating New Zealand’s introduced pests by 2050. The newest proposal is genetic engineering and modification of Possum’s DNA, through a process of CRISPR/Cas9-gene-drives to slowly eliminate those which harm NZ’s endemic species. CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats. Genetic engineering includes the hijacking of the CRISPR/Cas9 system found in bacteria to change any chosen letter(s) of an organism’s DNA code. CRISPR/Cas9 is a modified Gene Drive system which is used to be ‘virus-destroying’ scissors which cut a section of DNA. The CRISPR/Cas9 Gene Drive is engineered to find the specified section of DNA to cut which sends the cells into repair mode. The ‘CRISPR’ part of CRISPR/Cas9 provides a donor DNA that has homology on both ends to the cut piece of DNA but has different genetic material in the middle. This false DNA is used in the repair process of the genome which ‘fools’ the cells into changing the genetic code. The way this will be used for PF2050 is by altering Possum’s genetic makeup so male possums will only produce Y chromosomes and when mated with a female possum, only reproduce male offspring.
The second biological process for the gene drive is to capture the pests, most commonly Possums, from the wild and inseminate them through a process of IVF. An embryo is taken from the Possums and genetically modified using the CRISPR/Cas9 gene drive. This modified embryo is inserted into the female Possum who then gives birth to male offspring who carry the modified gene. After controlled experiments and reproduction, the gene becomes dominant. Once the gene is dominant, the Possum’s are released into wild to mate with other possums and only produce male offspring. Thus, eradicating the population.
With the introduction of the gene drive, the population of pests including Possums will slowly begin to reduce. As the population diminishes, the competition between Possums with NZ’s Flora and Fauna will change. This introduces a new biological concept of predation and competition. At the current moment, New Zealand’s native birds, plants and ecosystems are under threat by the predation of introduced pests. Entire bird species are facing endangerment by Possums and Stoats as they compete for common food sources. Possums diet generally includes buds, flowers, nectar, leaves and fruit/berries which makes them large competitors of native NZ birds and mammals [3]. With the eradication of pests such as Possums, the Horticulture of NZ will begin to repair and replenish itself.
A biological implication of using the CRISPR/Cas9 gene drive with Possums is the potential for the modified gene to spread to populations outside of the target zone. The possibility of the manipulated gene spreading to additional populations complicates discussions on ethical value – how and whether to proceed with intervention. The likelihood of the CRISPR/Cas9 gene drive spreading to other populations is a high risk, even with the development of resistance in the drive systems. Mathematical models predict that this development will not prevent manipulated gene drives from spreading to most populations connected by gene flow [7]. This is a biological implication to New Zealand Possums as it is not entirely guaranteed that the modified gene-drives would not spread to non-target populations or the likeliness that the modified possums could be smuggled to Australia. As Australia does not consider possum’s as pests, there is the chance that the gene drive could make its way to Australian possums and kill a protected species.
A social implication of using CRISPR/Cas9 is the economic growth that would occur within New Zealand’s economy. The dairy industry is one of the most valuable in NZ with exports worth around $6.5 billion in 2017 [4] but, the NZ cattle and deer farming industries are under serious threat by Bovine Tuberculosis (TB), a contagious disease carried by Possums. Possums carrying TB are lethargic and tend to stay out during the day. Curious cattle which sniff and lick dying, or dead possums are infected with TB and most die within 6 months of contracting the disease. Possums and ferrets are responsible for over 70% of infection in cattle and deer herds. In 2014, it was seen that 0.1% of NZ’s cattle was infected with TB where many of our competitors such as North America and Australia are TB-free [6]. This causes detriments to the economic growth of the horticulture in NZ. Alongside causing disadvantages to the dairy and meat industries, an additional $27 million has already been spent in research, herd testing and compensation for TB. This is why the introduction of CRISPR/Cas9 benefits the NZ economy, as implementing genetic modification into the Possums chromosomes, would eventually eliminate the population, and the main carriers of TB with it.
In my opinion, I believe that using the CRISPR/Cas9 gene drives is a really smart idea, albeit more research needs to be deduced before it is implemented into our society. It is a cheaper and easier technology to use, that is also tremendously versatile [9]. The biological implication of the modified gene-drive spreading to unintended populations creates controversy, however, a new solution has been proposed by Kevin M Esvelt to address this issue – a self-limiting version of CRISPR gene drives called a “Daisy chain drive”. The daisy-drive splits the gene drive up into three or more parts in a ‘daisy-chain’ manner. Esvelt calls these ‘elements’ and each contains 1 or more genes that contribute to the gene drive as a whole. The Elements can be labelled element A, B or C, where A cannot copy and paste itself if B is not present, and B cannot copy and paste itself if C is not present. Element C cannot copy and paste itself at all, it can only be spread by normal breeding. When a large number of Possums are implemented with the daisy-drive and are released to mate with wild Possums. All of the offspring inherit the elements A and B but only half will inherit C due to natural breeding. A and B will spread rapidly whereas C will slowly die out and with it, A and B [8]. With the introduction of the daisy-chain drive, the gene-drive will not spread indefinitely, and it immensely reduces the risk of Possums with the modified gene to cross to non-targeted species or to Possums in other countries. This makes me believe that using CRISPR/Cas9 gene-drives can be a safe and effective option which is guaranteed to reach the PF2050 goal.
The effectiveness of this proposed action would be extremely effective as the daisy-drive system provides a reprieve for the ethical side of things. With the controlled release of daisy-drives and the drive systems not spreading indefinitely, it allows differing communities to either partake or to reject implementing the modified Possums. The daisy drives would only affect local environments which allows for safe testing within the wild and in a controlled area. It allows scientist’s research to be for the public view and for society to make a judgement on CRISPR/Cas9. To stop the modified genes to cross to non-target populations through natural gene flow, scientists can implement the ‘Daisy Quorum Drive’ which swaps two genes required for the organism’s survival but as long as the daisy drive is inherited, both will be inherited. Through a natural process of mating, eventually some organisms will inherit only one of the crucial gene’s which means those with only one of the genes will die. This means it’s a good idea for modified Possums to mate with other modified possums, and un-modified to mate with each other, but mixing the two populations would be penalized. This helps to confine the modified Possums to area’s where communities consent to the use of gene-drives and exclude populations where communities are unconsensual [13].
Because of the complications that come with using CRISPR/Cas9 gene-drives, it creates differing viewpoints on this issue. One viewpoint which agrees with the use of CRISPR/Cas9 for NZ Possum’s is from Geoff Simmons, Opportunities Party leader and a journalist for The Spin Off. He believes that using gene-editing (GE) to help solve NZ’s drastic environmental issues is the best course of action.
“Gene editing is one of the most promising ways of achieving a predator-free New Zealand, so we can stop using poisons like 1080.” [10]
Simmon’s address’s the point that the current method of 1080 to kill off NZ’s pests is poisoning the environment and the ecosystems that are in affected areas. He knows that by switching to GE, NZ uses a cheaper and more effective technology which is safer for the surrounding environment. He believes that the key to New Zealand’s bright and environmentally friendly future is to stop looking solely in the past by innovating to meet the challenges ahead.
Against:
I accept that several of my sources have a strong degree of bias to them. For Example, The Spin Off is a New Zealand online magazine covering politics, pop-culture and social issues [10], where the author, Geoff Simmons, of all GE affiliated issues is strongly for the use of CRISPR/Cas9 in NZ. Geoff Simmons is an economist and the manager of the Morgan Foundation – a charitable trust that primarily was founded for the purpose of improving the lives of poorest folk, but their work extends to New Zealand public interest research [11]. The Morgan Foundation funds projects such as ‘The science of Climate Change’ and ‘The big Kahuna’ which deals with social/environmental issues within New Zealand. The Morgan Foundation are also strong supporters of New Zealand’s native flora and fauna, which is evidently seen in the article ‘Rejoice: A predator-free NZ is no longer a dream,’ [12]. This gives the indication that Morgan Foundation and Geoff Simmons have the belief that GE is a good idea for NZ. The Spin Off is also supported by The University of Otago with its publication of GE articles. It is known that all Universities have a known bias and with this we can conclude that the article has a bias towards using GE in NZ. To counter this bias, I made sure to only use a wide range of sources that are accepted within the scientific community as my factual biology. I gathered information from websites such as Te Ara – the encyclopedia of NZ, the Department of Conservation NZ, and the Plos Biology Journals which have been scientifically peer reviewed and published online.
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