Genetic engineering debuted in 1972 when Paul Berg created a unique virus by combining genes from the monkey and the lambda viruses. Truth be told, we humans have been in the artificial selection business for millennia, breeding domesticated plants and animals for desirable traits. The only difference is that prior to 1972 the attributes were acquired from naturally occurring point mutations, gene duplication or deletion within a species.
In the ensuing decades, DNA both naturally and synthetically derived has been inserted into host organisms to create food crops resistant to herbicides, insect pests, drought, viruses, saline soils, certain heavy metals, and frost. Bacteria, yeast and algae have been modified to produce insulin, pharmaceuticals, biofuels, and remediate oil spills or other environmental contamination. Genetically modified mammalian cell lines produced vaccines.
Early modification methods were inexact. For plants, a plasmid (a DNA ring) was inserted into Agrobacterium tumefaciens bacteria, which then infected small batches of plant tissue. Cells with the desired trait were replicated via tissue culture. Animal cell nuclei were directly microinjected with the pertinent genetic material. Naturally or synthetically sourced plasmids were introduced into microbial cells by chemical carriers or with heat or electric shock. The result was usually a free-floating DNA segment distinct from the host genome, or in the case of Agrobacterium infection, the genetic material was spliced into the host genome in random locations.
But the discovery and deployment of CRISPR technology in 2012 by the all-female research team of Emmanuelle Carpentier and Jennifer Doudna ushered in a new era of highly accurate gene deactivation and/or insertion.
CRISPR is bacterial in origin. It's a form of microbial immunization against bacteriophages (viruses). Small portions of the virus genome are spiced into the bacterial genome. When transcribed into RNA, this "guide" is incorporated into a nuclease enzyme generated from an adjacent gene. The resulting complex latches onto the invading virus's matching base pairs, slicing and deactivating the virus DNA.
Carpentier and Doudna paired CRISPR RNA guides with the Cas-9 nuclease to more accurately target different locations within genomes. The CRISPR-Cas9 system has generated a lot of excitement in the scientific community, being faster, cheaper, more accurate, and more efficient than earlier genome editing methods. Today, scientists can tailor the RNA guides to pinpoint specific desired loci within a genome. Dozens of different nucleases can perform single or double DNA strand cuts, and even single base pair substitutions.
This ushered in the current (and future) rush of medical gene therapies. Gene splicing systems allow otherwise missing enzymes and proteins and their lost function to be restored. Disease targets include lymphomas, cancers, retinal degeneracies, muscle dystrophies, immunodeficiencies, hemophilia, and dozens of other conditions.
Gene therapy treatments are somatic. The genetic modifications are not heritable. Genetic engineering of human germ cells (eggs or sperm) is highly restricted and ethically dubious at best. As targetable as CRISPR is, it can and does affect non-target areas of a genome, leading to unintended deleterious consequences for offspring.
Using germline editing for reproduction is prohibited by law in the United States plus more than forty other countries and by a binding Council of Europe international treaty. My descendants may be able to get their "cool gene" treatments, but they won't pass on their newfound trait to their children. Bummer.
So, what does genetic engineering have to do with Mars? I foresee two applications in the first decade of colonization. The first will be modified food crops.
Perchlorate (ClO4-), toxic to humans and plants, is ubiquitous in Martian regolith. It will need to be removed before crops can be grown. Perchlorate salts are highly water soluble. The easiest method for removal from soil will simply be to flush it out with water. The effluent will still contain biologically useful minerals. And because water itself will be a precious commodity on Mars, it will have to be treated for reuse in irrigation.
Perchlorate can be removed from the effluent by ion transfer. Those who live in regions with hard water are familiar with this. Water softening exchanges calcium ions with sodium, making tap water more suitable for drinking, cooking and bathing. On Mars, perchlorate will be exchanged for less-toxic anions--probably chloride. While less toxic to crops, the effluent will still be saline. So, crop plants may need to be genetically modified to tolerate the salinity.
Fertilizers will be difficult to come by. Nitrogen only comprises 2.7% of the already thin Martian air. By contrast, Earth's atmosphere is 78% nitrogen. Nitrogen will be expensive on Mars. It must be shipped there from Earth or harvested from the meager Martian atmosphere. Either way, crops grown on Mars must be able to fix nitrogen from the colony air supply, whether directly or by hosting nitrogen-fixing bacteria like legumes do.
I don't doubt that the first attempts to grow crops on Mars will reveal other deficiencies that we simply take for granted in Earth's biologically rich soil ecosystems. Crop plants will need to be modified to perform those missing ecological services usually performed by soil microbes.
The other application used in Mars colonies will be gene therapies. Early colonizers must contend with a dual health threat. High doses of cosmic radiation experienced while on the surface(and potentially transiting to and from Mars) will lead to statistically high incidences of lymphomas and certain cancers. Poor availability of return transit, coupled with the months-long travel time, means patients could die of aggressive disease before receiving treatment on Earth.
Gene sequencers, some form of CRISPR lab-in-a-box, and sterile cell incubators to propagate modified immune cells could be shipped to Mars within the first decade.
Human colonizers will face an array of challenges on Mars. But genetic engineering will make a few of them less daunting.
For Further Readinghttps://en.wikipedia.org/wiki/Genetic_engineeringhttps://medlineplus.gov/genetics/understanding/genomicresearch/genomeediting/https://en.wikipedia.org/wiki/CRISPRhttps://www.estherlandhuis.com/uploads/4/0/0/2/40025451/sciam-gene_therapy-nov_2021.pdfhttps://en.wikipedia.org/wiki/Gene_deliveryhttps://www.nature.com/scitable/topicpage/genetically-modified-organisms-gmos-transgenic-crops-and-732/https://en.wikipedia.org/wiki/Perchloratehttps://en.wikipedia.org/wiki/CRISPR_gene_editing
