SUMMARY
The Cry1Ac gene found in our modification comes from the bacterium Bacillus thuringiensis, and thus is the gene placed in soybean plants. This gene produces delta endotoxin proteins, which form crystals that exert a specific toxin against some species of larvae. The crystal toxins then act as an insecticide against some species of feeding larvae, killing the larvae, and reducing its population while increasing the soybean population. The Cry1Ac gene occurs naturally in bacteria, but not in soybeans, which means that the modification is an example of synthetic genomics.
In terms of how information flows through the process specifically, the Cry1Ac gene produces delta endotoxin proteins, which, when expressed in the soybean plant, form crystals that exert a specific toxin against specific species of larvae. This then prevents the larvae from feeding on the soybean and growing further or resulting in death. These toxins that are formed act as a sort of insecticide, preventing larvae from feeding on the soybean, stunting the larvae population growth, and increasing the soybean survivability and ultimately its development (Homrich, et al. 2012).
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The synthetic Bt cry1Ac gene is cloned into the plant expression vector pIC35/A, which contains and marker, promoter, and terminator. Using the synthetic gene allows for a greater expression of the gene in the total mRNA of the soybean than if Bt had been inserted into a native gene. The synthetic gene is a plasmid made up of specific restriction sites with ampicillin resistance used as a bacterial marker (Stewart, et al. 1996). The gene allows for the endotoxins to be produced during sporulation, where the protein is included in the cytoplasm of soybeans and in the spore coat. When the insect larvae eat the crystals, the toxic crystals bind to epithelial cells in the larvae stomachs, which then causes cell lysis in larvae.
In terms of interactions of multiple levels, there is an interspecific interaction on the organism level between the larvae and the soybeans, and there is an interaction on the cellular level between the endotoxins and the larvae organ system. In the first interaction, without the modification, it is an herbivory reaction, where the larvae feed on soybean plants to gain energy, and thus the soybeans lose energy and its population decreases. With the modification, it changes to a pathogen reaction, where the toxins in the plants disrupt the process and promote the soybean’s own growth and development. The interaction on the cellular level relates to the Bt gene causing crystal endotoxins to form on the leaves of the soybean plant. The concurrent interaction between organ systems relates to the disruption of osmotic processes in the stomach of the larvae, preventing larvae growth or causing larvae death (Stewart, et al. 1996). The toxins that formed act as a sort of insecticide, preventing larvae from feeding on the soybean, stunting the larvae population growth, and increasing the soybean survivability and ultimately its development (Homrich, et al. 2012).
A change in energy flow can be seen in the interaction between larvae and soybeans, as originally, without the genetic modification, the larvae would ingest the soybean for food and energy. With the genetic modification, the osmotic processes in the stomach of the larvae are disrupted, preventing larvae growth or causing larvae death (Stewart, et al. 1996). Thus, the transfer of energy from the food (soybean) to the consumer (larvae) is interrupted, as the endotoxin crystals found in the soybean cause damage to the larvae and promote its own growth and development. The interaction changed from herbivory (plant gets eaten by the larvae) to pathogen (where the plant produces toxins that affects the larvae in return). In addition, the limited herbivory interaction allows for a larger soybean population, which then allows for photosynthesis to increase. As the larvae die out, the process of cellular respiration decreases, and less chemical energy is transferred through the system as a result. As the soybean plant population increases and the larvae population decreases, the entire food chain becomes disrupted.
The Cry1Ac gene is an example of synthetic genomics, where a gene is expressed that would not naturally occur in nature. In that sense, this modification is not a modification that could not necessarily have arisen from evolution. Since the gene also comes from bacteria and was then inserted into a plant, it is unlikely to have been done so naturally. However, there are alternate forms of insect resistance that have been introduced through the process of evolution, like a bitter tastes or increased protection. Therefore, the notion of insecticides and protection from pests within plants themselves remains a factor, as soybeans could have developed their own resistance which might not have involved this particular gene but might have evolved in another way.
For this particular modification, there is a range of impacts on society, from positive to negative and to unknown. The most positive impact is that the modification allows for a reduction in the need for pesticides, which then allows for farmers to spend less money on pesticides and thus facilitates management of crops. Ultimately, this also allows for the farmers to produce greater quantities of crops, which can help distribute these crops more evenly across socioeconomic classes as they become easier to afford and purchase. However, there are some potential hazards which can occur with the implementation of the gene, and how it might affect surrounding plant species in unknown ways or affect other predators in a similar manner to the larvae. The research on this particular modification is ongoing, and as of now there are still many unknown direct consequences to the gene expression in soybean plants. The major negative impact comes from farmer dependence on genetic engineering companies, where farmers then have to rely on large companies (like Monsanto) to produce and distribute their crops, which goes back partly on the increase in money from less pesticide use from earlier.
While the social stigma regarding genetic modification and genetically modified foods in particular has remained mostly negative, there has been a lot of change throughout recent years, and the way of genetics is changing as we speak. Scientists are on a path of creation and discovery, and once the public has become more comfortable with genetic modification, the future will bring a great many new things.
REFLECTION
At the beginning of this process, I was excited to learn about genetically modified foods, as I was curious about the different types of modifications that can be found in our current food market. As I continued to research this modification, I found the information really interesting, and I’m definitely more interested now than I was before in genetic engineering especially in food. I think this particular genetic modification proves to be very useful in protecting soybeans from specific types of larvae, and I think this modification could be used to enhance all forms of crops against all sorts of predators. This would then increase the crop population across the world, and just that many more people would be able to access these crops and thus have more food to survive. As mentioned before, there are both positive and negative repercussions on society and social classes from the modification that we chose. The most positive being that it reduces the need for pesticides, which then allows for farmers to produce more crops, spend less on pest control, and thus earn more money. This then allows for a greater range of distribution among all different social classes. However, the farmer then becomes dependent on large genetic engineering companies like Monsanto, where instead of relying on themselves and their own products, they are forced to comply with the rules and regulations of a large company that may not care about the farmer’s direct welfare.
This class (Biology 100F: Genetic Engineering) was absolutely jam packed with information and material, and I felt as if I learned about a new part of our social world in relation to biology, which I didn’t expect to learn about. I learned so much about genetics and I’m really impressed with how much ground we covered in what seemed like a really short semester. I really enjoyed having small group discussions that lead into large class discussions, as I liked hearing other perspectives and opinions that weren’t necessarily similar to my own. I was surprised to realize the range of social impacts that this modification has on society, from positive, to negative, to still unknown. I was also surprised to learn how much of our daily food has already been genetically modified in order to survive, like grapefruit, corn, bananas, etc. I think I will take away many things from this class, ultimately that the world as we know it is complicated, and although many more rules, regulations, and standards need to be resolved and determined before there is any sort of public acceptation of genetic modification, the tides are turning. Genetic modification and genetic engineering have become a part of our lives, for the better or the worse (hopefully the former) and is not going anywhere anytime soon.
LITERATURE CITED
- Homrich, M. S., Wiebke-Strohm, B., Weber, R. L. M. & Bodanese-Zanettini, M. H. Soybean genetic transformation: A valuable tool for the functional study of genes and the production of agronomically improved plants. Genetics and molecular biology (2012). Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3571417/. (Accessed: 20th October 2019)
- MUC1 gene - Genetics Home Reference - NIH. U.S. National Library of Medicine (2019). Available at: https://ghr.nlm.nih.gov/gene/MUC1. (Accessed: 20th October 2019)
- Stewart, C.N. & Adang, Mike & All, John & Boerma, H.R. & Cardineau, Guy & Tucker, D & Parrott, Wayne. Genetic transformation, recovery, and characterization of fertile soybean transgenic for a synthetic Bacillus thuringiensis cryIAc gene. Plant Physiol (1996). Available at: http://www.plantphysiol.org/content/plantphysiol/112/1/121.full.pdf. (Accessed 5th November 2019).
- Unglesbee, E. Monsanto Halts Plan for Bt Soybeans in US. DTN Progressive Farmer (2018). Available at: https://www.dtnpf.com/agriculture/web/ag/crops/article/2018/05/09/monsanto-halts-plan-bt-soybeans-us. (Accessed: 11th December 2019)
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