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July 2, 2019 - July 8, 2020
All cells are exposed to DNA-damaging agents, such as x-ray radiation and carcinogens, and cells are remarkably efficient at repairing those breaks without losing genetic information. According to Szostak’s model, that repair process depended on the ability of chromosomes to match up via homologous recombination, which might be why having two copies of a chromosome was a beneficial evolutionary strategy. Any damage to one chromosome could be repaired simply by copying the matching sequence on the second chromosome.
Putting the pieces together, d’Herelle concluded that a parasite—what he called a bacteriophage, or “eater of bacteria,” a life form small enough to pass through the filter—had destroyed the Shigella bacteria. This bacteriophage seemed to infect bacteria in much the same way that viruses infected plants and animals.
got their first glimpses of phages in the 1940s and 1950s, using new high-magnification electron microscopes,
Scientists estimate that there are somewhere on the order of 1031 bacteriophages on earth; that’s ten million trillion trillion, or a one with thirty-one zeros after it. A single teaspoon of seawater contains five times more phages than there are people in New York City. Incredibly, there are many, many more phages on earth than there are bacteria for them to infect; as abundant as bacteria are, bacterial viruses outnumber them ten to one. They cause roughly a trillion trillion infections on earth every second, and in the ocean alone, about 40 percent of all bacteria die every day as a result
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Streptococcus thermophilus, one of the key probiotics involved in producing yogurt, mozzarella cheese, and numerous other dairy products.
Gene-expression control—the complex and overlapping inputs that govern when and for how long genetic information in the form of DNA is turned into protein—is arguably as important to biology as the underlying genetic information itself.
Think of the cell as the largest symphony in the world, made up of more than twenty thousand different instruments. In a healthy, normal-functioning cell, the various symphonic voices are perfectly balanced; in malignant cancer cells or infected cells, the balance is disrupted, with some instruments playing too loud and others too soft.
Sometimes, DNA editing is too crude an approach to return the symphony to its normal state—it would be akin to removing or replacing instruments outright. The deactivated CRISPR system offers a way to fine-tune any instrument in the orchestra—that is, any gene in the genome—with greater sensitivity.
Addgene is like Netflix, only for plasmids.
It’s become something of an old saw in our young field: what used to require years of work in a sophisticated biology laboratory can now be performed in days by a high school student.
set up a CRISPR lab for just $2,000.
crowdfunded venture that raised well over fifty thousand dollars to generate and distribute DIY gene-editing kits. For $130, donors received “everything you need to make precision genome edits in bacteria at home.”
poised to turn this once-esoteric practice into a hobby or a craft, just like homebrewing beer.
In many ways, this is exciting—but there’s also something unsettling about the rapid spread of this powerful tool.
lead to uses of this technology that people are not yet prepared for—and whose effects can’t be contained within the lab.
Weighing the dangers inherent in a technology like CRISPR against the responsibility to use its power for the benefit of humanity and our planet will be a test like no other. Yet it’s one that we must pass.
genetically engineered pigs that can serve as human organ donors—but
woolly mammoths, winged lizards, and unicorns. No, I am not kidding.
I love the notes and pictures colleagues send me describing their CRISPR experiments—the beautiful butterfly-wing patterns whose genetic underpinnings they’ve uncovered, or the infectious yeast whose ability to invade human tissues they’ve dissected at the level of individual genes. These kinds of experiments reveal new truths about the natural world and about the genetic similarities that bind all organisms together. They’re enormously exciting to me.
resurrection of extinct species
forcible extinction of unwanted animals or pathogens.
Some of the efforts in these and other areas of the natural world have tremendous potential for improving human health and well-being. Others are frivolous, whimsical, or even downright dangerous. And I have become increasingly aware of the need to understand the risks of gene editing, especially in light of its accelerating use.
barley breeders.
As pioneering agriculturist Luther Burbank remarked in a speech in 1901, species weren’t fixed and unchangeable but rather “as plastic in our hands as clay in the hands of the potter or colors on the artist’s canvas, and can readily be molded into more beautiful forms and colors than any painter or sculptor can ever hope to bring forth.”
alter two soybean genes, generating seeds with a drastic reduction in the unhealthy fatty acids and an overall fat profile similar to that of olive oil. They accomplished this without causing any unintended mutations and without introducing any foreign DNA into the genome.
The lengthy cold storage required to increase potatoes’ shelf life can lead to cold-induced sweetening, a phenomenon in which starches are converted into sugars such as glucose and fructose. Any cooking process involving high heat—necessary to make french fries and potato chips—converts these sugars into acrylamide, a chemical that is a neurotoxin and a potential carcinogen.
Knowing that gene-edited plants and animals will inevitably be compared to GMOs, I’ve specifically committed myself to learning what different national governments and public-interest groups even mean when they use the term genetically modified organism.
“the production of heritable improvements in plants or animals for specific uses, via either genetic engineering or other more traditional methods.”
A more common definition of GMO, however, includes only those organisms whose genetic material has been altered using recombinant DNA technology and so-called gene splicing, in which foreign DNA sequences are integrated into the genome.
there is near-unanimous consensus that GM food is every bit as safe as conventionally produced food.
Nevertheless, nearly 60 percent of Americans perceive GMOs as unsafe.
The disjunction between scientific consensus and public opinion on the topic of GMOs is disturbing, to say the least. I see it as partly a reflection of the breakdown in communication between scientists and the public at large. Already in my relatively short time working on CRISPR, I’ve discovered how challenging it can be to maintain a constructive, open dialogue between these two worlds—but also how necessary that kind of communication is for the advancement of scientific discoveries.
Almost everything we eat has been altered by humans, often by generating random mutations in the DNA of seeds used to breed plants with desired traits.
Conventional GMOs contain foreign genes randomly inserted into the genome; these genes produce novel proteins that give the organism a beneficial trait it did not previously possess. Gene-edited organisms, by contrast, contain tiny alterations to existing genes that give the organism a beneficial trait by tweaking the levels of proteins that were already there to begin with—without adding any foreign DNA.
Some of the first activist-led protests over the new technology took place in the spring of 2016.
In many ways, the issue boils down to product versus process: Should regulations for a newly generated crop consider only the final product, or should they also take into account the process that was employed to develop it?
unless public attitudes toward genetically enhanced foods change with them, we as a society won’t be able to benefit from the full potential of CRISPR.
Biotechnology can help us shore up our food security, stave off malnutrition, adapt to climate change, and prevent environmental degradation around the world.
GMO salmon breed,
gene-spliced salmon contains an extra growth hormone gene, resulting in a fish that reaches market weight in half the time of a conventionally farmed salmon
“Frankenfish”
Enviropig,
The AquAdvantage salmon was endowed with a growth hormone gene from Chinook salmon as well as a short piece of DNA from ocean pout to keep the growth hormone gene switched on. What if, instead, scientists had somehow managed to edit the salmon’s genome to ramp up production of its own growth hormone gene without adding any foreign DNA? Would consumers and regulators still consider the salmon a GMO?
double muscling.
In Australia, a team is trying to alter a gene in chickens that produces one of the most common allergenic proteins in chicken eggs, and similar strategies have been proposed to remove allergens in cow milk.
modifying cows to prevent them from growing horns.
might have been produced by years of conventional breeding. Gene editing merely allowed the same outcome to be achieved much more efficiently.
bench-to-bedside
Someday soon, we might be using pigs as bioreactors to produce valuable drugs like therapeutic human proteins, which are too complex to synthesize
looking to other transgenic animals to produce these biopharmaceutical drugs, or farmaceuticals, as they’re colloquially called.
