Eric Lander wrote an excellent article reviewing the history of CRISPR. It is well-written and covers fascinating stories about the early scientific work of some of the key players. A take-home message is that unusual discoveries in basic science do not start from the heavily funded famous labs. Kudos to Lander for recognizing the roles of young, unknown and risk-taking scientists in pursuing such discoveries.
The abstract and couple of examples of key contributors are posted below.
Three years ago, scientists reported that CRISPR technology can enable precise and efficient genome editing in living eukaryotic cells. Since then, the method has taken the scientific community by storm, with thousands of labs using it for applications from biomedicine to agriculture. Yet, the preceding 20-year journeythe discovery of a strange microbial repeat sequence; its recognition as an adaptive immune system; its biological characterization; and its repurposing for genome engineeringremains little known. This Perspective aims to fill in this backstorythe history of ideas and the stories of pioneersand draw lessons about the remarkable ecosystem underlying scientific discovery.
Story of Mojica
The story starts in the Mediterranean port of Santa Pola on Spains Costa Blanca, where the beautiful coast and vast salt marshes have for centuries attracted vacationers, flamingoes, and commercial salt producers. (The geography of the story is shown in Figure 2.) Francisco Mojica, who grew up nearby, frequented those beaches, and it was no surprise that, when he began his doctoral studies in 1989 at the University of Alicante, just up the coast, he joined a laboratory working on Haloferax mediterranei, an archaeal microbe with extreme salt tolerance that had been isolated from Santa Polas marshes. His advisor had found that the salt concentration of the growth medium appeared to affect the way in which restriction enzymes cut the microbes genome, and Mojica set out to characterize the altered fragments. In the first DNA fragment he examined, Mojica found a curious structuremultiple copies of a near-perfect, roughly palindromic, repeated sequence of 30 bases, separated by spacers of roughly 36 basesthat did not resemble any family of repeats known in microbes (Mojica et al., 1993).
The 28-year-old graduate student was captivated and devoted the next decade of his career to unraveling the mystery.He soon discovered similar repeats in the closely related H. volcanii, as well as in more distant halophilic archaea. Combing through the scientific literature, he also spotted a connection with eubacteria: a paper by a Japanese group (Ishino et al., 1987) had mentioned a repeat sequence in Escherichia coli that had a similar structure, although no sequence similarity, to the Haloferax repeats. These authors had made little of the observation, but Mojica realized that the presence of such similar structures in such distant microbes must signal an important function in prokaryotes. He wrote up a paper reporting this new class of repeats (Mojica et al., 1995) before heading off for a short post-doctoral stint at Oxford.
Story of Horvath
Lander managed to get the word ‘sexy’ approved in scientific journal in describing thesis, which itself is another major achievement :)
Like Mojica, Philippe Horvath could hardly have chosen a thesis
topic that was more local or less sexy. As a Ph.D. student at the University of Strasbourg, he concentrated on the genetics of a lactic-acid bacteria used in the production of sauerkrautthe central ingredient in the Alsatian specialty choucroute garnie. Given his interest in food science, Horvath skipped doing postdoctoral research and in late 2000 joined Rhodia Food, a maker of bacterial starter cultures located in Dange -Saint-Romain in western France, to set up its first molecular biology lab. The company was later acquired by the Danish firm Danisco, which was itself acquired by DuPont in 2011.
Rhodia Food was interested in Horvaths microbiological skills because other lactic-acid bacteria, such as Streptococcus thermophilus, are used to make dairy products, such as yogurt and cheese. Horvaths mission included developing DNA-based methods for precise identification of bacterial strains and overcoming
the frequent phage infections that plagued industrial cultures used in dairy fermentation. Understanding how certain S. thermophilus strains protect themselves from phage attack was thus of both scientific interest and economic importance.
The lessons of CRISPR
The story of CRISPR is rich with lessons about the human ecosystem that produces scientific advances, with relevance to funding agencies, the general public, and aspiring researchers. The most important is thatmedical breakthroughs often emerge from completely unpredictable origins. The early heroes of CRISPR were not on a quest to edit the human genomeor even to study human disease. Theirmotivations were amix of personal curiosity (to understand bizarre repeat sequences in salttolerant microbes), military exigency (to defend against biological warfare), and industrial application (to improve yogurt production). The history also illustrates the growing role in biology of hypothesis-free discovery based on big data. The discovery of the CRISPR loci, their biological function, and the tracrRNA all emerged not from wet- bench experiments but from openended bioinformatic exploration of large-scale, often public, genomic datasets. Hypothesis-driven science of course remains essential, but the 21st century will see an increasing partnership between these two approaches.
It is instructive that so many of the Heroes of CRISPR did their seminal work near the very start of their scientific careers (including Mojica, Horvath, Marraffini, Charpentier, Vogel, and Zhang)in several cases, before the age of
- With youth often comes a willingness to take riskson uncharted directions and seemingly obscure questionsand a drive to succeed. Its an important reminder at a time that the median age for first grants from the NIH has crept up to 42.
Notably, too, many did their landmark work in places that some might regard as off the beaten path of science (Alicante, Spain; Frances Ministry of Defense; Daniscos corporate labs; and Vilnius, Lithuania). And, their seminal papers were often rejected by leading journalsappearing only after considerable delay and in less prominent venues. These observations may not be a coincidence: the settings may have afforded greater freedom to pursue less trendy topics but less support about how to overcome skepticism by journals and reviewers.
Finally, the narrative underscores that scientific breakthroughs are rarely eureka moments. They are typically ensemble acts, played out over a decade or more, in which the cast becomes part of something greater than what any one of them could do alone. Its a wonderful lesson for the general public, as well as for a young person contemplating a life in science.