Chemist Irving Langmuir, who pioneered the study of thin films and interfaces, won the 1932 Nobel Prize for his work at General Electric, and came up with a theory about creating a form of solid water that was stable at room temperature, like ice–he supposedly did this hoping that Science Fiction author HG Wells might be inspired to write a story about it. Wells did not, but Kurt Vonnegut, who discovered Langmuir’s idea while working at GE, used it for an idea (Ice 9) in his book Cat’s Cradle.
Fast forward to 2010 and a gene-editing technique called Crispr-Cas9 seems every bit as remarkable. The first term is an acronym for “clustered regularly interspaced short palindromic repeats,” a description of the genetic basis of the method; Cas9 is the name of a protein that makes it work. Crispr-Cas9 allows biogenecists to move genes around—any genes, in any living thing, from bacteria to people.
Oddly, it was yogurt cultures that led to this breakthrough. Researchers sequencing the genomes of of the world’s oldest bacteria and microbes( Archaea, genetically connected to the oldest known life forms), recorded recurring segments of DNA that were identical, genetic palindromes (A palindrome is a word, phrase, number, or other sequence of characters which reads the same backward or forward). They had no idea what they did, but they did understand they were special. The called them Crispr (clustered regularly interspaced short palindromic repeats).
In 2005, a microbiologist working at a Danish food company called Danisco, noticed palindromic repeats in the bacteria they used to make yogurt, and that they matched sequences from viruses that had infected their S. thermophilus colonies. Bacteria, like anything else, and get infected by viruses—these viruses are called phages. The sequences they discovered in bacteria are actually an integral part of their defense against the phages, a sort of immune system architecture stored in memory. Once a phage infects a microbe , if that Crispr was previously stored in memory, it would recognize the phage and fight back.
More research into sequencing bacteria found that some of Crispr’s sequences led to the creation of not DNA protein, but RNA, a single-stranded genetic material. Since most things, plants and animals use single stranded RNA structures to fight off viral infections, researchers began to believe that Crispr was an elemental, primeval immune system structure.
Crispr creates two strands of RNA, and a remarkable protein named Cas9, attaches itself to them. Once that occurs, the RNA strands and Cas9 now correspond to the infecting virus’ DNA; acting like a map or gps, Crispr and Cas9 search after the virus. Once Cas9 finds the matching viral sequence it morphs into a new shape, takes hold of the viral DNA and begins to slice and take it apart.
This discovery led researcher Jennifer Doudna to take the the two strands of RNA and combine them into one fragment called a “guide RNA”. This ‘guide’ could be programmed using almost any genetic makeup, and then sent off to perform its DNA cutting work.
Note: researcher’s in China claim they have used Crispr to edit the genome of human embryos.
A report in MIT’s Technology Review revealed that in Monsanto’s labs near St. Louis, they have been experimenting with a similar technique called RNA interference, where a gene can be completely shut down. In the report, they show how Monsanto’s technique could shut down a gene an insect needs to survive, in this case the Colorado potato beetle. Green leafy plants were doused with RNA, and after feeding, 99% of the beetles died.
Note: See this story on how Monsanto’s Roundup is hurting Monarch Butterfly populations.
Image courtesy of honeybeesuite.com
It’s easy enough to get bugs to ingest RNA, but the next step is to infuse or penetrate the actual plant cells, where it could use a spray to block certain genes—this could be used for drought resistance, or even make something like a tomato taste better. That is, modifying the plants genes without messing with the genome, and in the process, avoiding the time and expense of creating a GMO. On the front lines, these materials could be whipped up to quickly address an insect infestation, drought, damaging mold, or a new type of virus. The effects of RNA interference degrade in soil quickly (usually in only a few days or weeks). An example might be, rather than designing a genetically modified plant that is drought resistant, just spray a normal plant in times of drought, and leave it alone when there is plenty of rainfall. Currently, there is no evidence that RNA is harmful to humans—in a letter to regulators, Monsanto stated that we have been ingesting RNA “ever since we have been eating”.
The U.S. Environmental Protection Agency is starting to get involved, and has asked a panel of experts to provide guidance on how to regulate RNA insecticides. This comes after the National Honey Bee Advisory Board brought up their RNA fears to the EPA , worried that more damage could be done to pollinators, that RNA interference could have unintended effects. Since the genomes of many insects have not been cataloged, it’s hard to tell if their genes will match an RNA target.
In short, what is the ecological risk? Monsanto’s own research has shown that RNA does have the ability to move between species. These latest discoveries point to a higher level of complexity, and begs the question of whether using these techniques in industrial agriculture poses the threat of unintended “ecological effects.”
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