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The discovery of CRISPR in archaea and bacteria
Open accessAbstract
CRISPR-Cas are self-/nonself-discriminating systems found in prokaryotic cells. They represent a remarkable example of molecular memory that is hereditarily transmitted. Their discovery can be considered as one of the first fruits of the systematic exploration of prokaryotic genomes. Although this genomic feature was serendipitously discovered in molecular biology studies, it was the availability of multiple complete genomes that shed light about their role as a genetic immune system. Here we tell the story of how this discovery originated and was slowly and painstakingly advanced to the point of understating the biological role of what initially was just an odd genomic feature.
Overview
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Written from the paper’s full text.
TL;DR
This is a historical account by Mojica and Rodríguez-Valera of how CRISPR was discovered in archaea and bacteria, beginning with an unexpected 30-bp repeat pattern in *Haloferax mediterranei* in 1992. It traces how exploratory prokaryotic genomics and spacer-matching analyses led to the recognition of CRISPR-Cas as an adaptive immune system.
Key findings
- The first CRISPR-like repeats were found serendipitously in *Haloferax mediterranei*: DNA segments 30 bp long repeated at regular distances, with at least 14 almost perfectly conserved repeats flanked at one end by a highly degenerated copy.
- Similar arrays were already known in bacteria: *E. coli* K12 had two DNA segments with 14 and 7 copies of a 29-bp sequence, and *Mycobacterium bovis* BCG had an array with 49 copies of a 36-bp direct repeat separated by 35–41 bp spacers.
- By the end of the century, regularly spaced repeats had been discovered in 12 species of archaea and bacteria, with open access to 26 completed microbial genomes; a comprehensive study showed wide distribution and hinted at ancestral origin and high biological relevance.
- Spacer analysis in *E. coli* showed that about 2% of spacers from 61 additional strains matched sequences in non-CRISPR loci, invariably in genetic elements of the corresponding spacer-carrier species, supporting CRISPR as an immunity system against foreign DNA.
Methods
- Historical narrative/perspective article, not a primary experimental study; it recounts the authors’ discovery process and the field’s development.
- Sources include the authors’ recollections, an unpublished Sanger sequencing gel dated 21/08/1992, an unpublished doctoral thesis, and published literature on CRISPR and prokaryotic genomes.
- Main analysis is chronological and descriptive, linking early repeat observations, genome sequencing advances, spacer database searches, and later experimental demonstrations by other groups.
Limitations
- Not stated in the paper: the article does not include a formal limitations section.
- Evident from the text: it is a retrospective personal account, so it may be shaped by recall and perspective rather than systematic review.
- Evident from the text: some reported experiments are unpublished results, and the authors describe publication rejections and lack of solid experimental evidence at the time, which limits the strength of the early immunity claims.
Model-written summary. Check it against the paper before relying on it.
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Claims the paper makes
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“When experiments equivalent to those previously performed in H. volcanii were replicated in E. coli, no clear phenotype was seen.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
Load-bearingStrength:boosted· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesIn the paper
“DNA segments, 30 bp long, were repeated at regular distances (Fig. 2A).”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
What the sources say
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In the paper
“In the exceptional cases where the cell harboured one of these protospacer-carriers, the similarity between the spacer and its homolog segment was markedly diminished with respect to the protospacer consensus sequence.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“Firstly, the possibility that TREPs could serve as frequent recombination sites, and hence recombination as the main biological role of TREPs, was dismissed.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“additional sequencing experiments confirmed the presence in this region of at least 14 almost perfectly conserved (one occasional mismatch) repeats flanked at one end by a highly degenerated copy.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“They were located in a, seemingly, noncoding area next to open reading frames (ORFs) that did not show homology to any known protein [4].”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“Moreover, additional studies did not provide any evidence of an involvement of the E. coli repeats in the partition apparatus.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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“Moreover, plasmids or viruses containing spacer-matching sequences (named protospacers) were usually absent in the spacer-carrier.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
What the sources say
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In the paper
“Even though salt-dependent transcription of genes surrounding the haloarchaeal repeats (by then called TREPs after Tandem REPeats) was detected, their implication in exclusively transcription regulation of a few genes was questionable due to the large size of the repeat loci.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“Then, three additional spacers were found to be similar to sequences in either that bacteriophage or in a conjugative plasmid of E. coli.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“Each repeat included short inverted repeats, thus being partially palindromic.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“CRISPR-RNA molecules were identified as the guides of this immune system [29]”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“Then, a reduction in cell viability detected in these cultures, concomitant with the appearance of cells with reduced chromosomal content, was seen as a sign of incompatibility between replicons containing the repeats, hinting at a role for TREPs in replicon partitioning [9].”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
What the sources say
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In the paper
“An array with 49 copies of a 36 bp direct repeat (DR), separated by nonrepetitive spacer DNA of 35-41 bp in length (Fig. 2C), was found in Mycobacterium bovis BCG strains [6].”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“Apparently, they were exclusively present in genomes carrying CRISPR.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“The identity of the spacer was a key determinant of the specificity of the resistance phenotype.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“Based on sequence similarity, some Cas were tentatively linked to activities related to interaction with nucleic-acids.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“This on-off swift of CRISPR immunity [17] could account for the results we obtained: interference was sporadically triggered by fortuitous de-repression.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“However, functional studies aiming to discover their biological role were only addressed in haloarchaea [9].”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“They also discovered a relevant aspect of the spacer homologs: the protospacers of a CRISPR system in Streptococcus thermophilus were juxtaposed to a short conserved sequence.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“Subsequently, a third paper along the same lines appeared [21], showing a positive correlation between spacer number and resistance to infection.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“Soon after this ground-breaking work, CRISPR interference against plasmid transfer through DNA targeting was shown [28]”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“But CRISPR-Cas are much more than a prokaryotic immune system.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
Load-bearingStrength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesIn the paper
“Thus, Barrangou et al. [27] found that S. thermophilus becomes resistant to infection by bacteriophages after the insertion of new spacers matching the virus genome.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“Two DNA segments with 14 and 7 copies, respectively, of a 29-bp sequence were identified in E. coli K12 (Fig. 2B).”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“Notably, they proved that the Cas proteins were indeed a functional component of the CRISPR systems.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
What the sources say
- Not matchedcites [27]
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“it was the availability of multiple complete genomes that shed light about their role as a genetic immune system.”
§ The discovery of CRISPR in archaea and bacteria > Abstract
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesIn the paper
“Furthermore, this inhibition can be relieved by the activator protein LeuO.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
What the sources say
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In the paper
“It was later reported that the CRISPR system of E. coli, at least that of K12-derivative strains, is usually silenced due to repression executed by the histone-like protein H-NS.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“In 2002, four genes encoding CRISPR-associated (Cas) proteins were identified nearby the repeat loci [16].”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“Many Cas proteins were biochemically characterized and their activity established [31].”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“and target cleavage was unveiled as the mechanism of interference [30].”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“The first comprehensive report of regularly spaced repeats in a complete genome was published in 1996 [12] and additional descriptions joined it in the following years.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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- It may state two separate claims as one. 15
- Probably not a substantial claim. 8
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“However, highly variable results were obtained upon deletion of phage-homologous spacers on susceptibility to infection, as well as when analysing transformation efficiency of recombinant plasmids containing spacer-matching sequences (unpublished results).”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
Load-bearingStrength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesIt may state two separate claims as one.
In the paper
“Then, a reduction in cell viability detected in these cultures, concomitant with the appearance of cells with reduced chromosomal content, was seen as a sign of incompatibility between replicons containing the repeats, hinting at a role for TREPs in replicon partitioning [9].”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
What the sources say
- Not matchedcites [9]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesIt may state two separate claims as one.
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In the paper
“To corroborate this finding, the spacers of 61 additional strains, including all available complete genomes, were subjected to the same sort of analysis, turning out that about a 2% of them matched sequences in non-CRISPR loci, invariably in genetic elements of the corresponding spacer-carrier species [11].”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
What the sources say
- Not matchedcites [11]
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Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesIt may state two separate claims as one.
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In the paper
“However, repeat binding proteins could not be recovered from cell extracts and topology of recombinant plasmids was not affected by the presence of repeat stretches.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
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In the paper
“This comprehensive study demonstrated the wide distribution of this sort of redundant sequences across a wide microbial diversity, hinting at an ancestral origin and high biological relevance [13].”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
What the sources say
- Not matchedcites [13]
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In the paper
“TREP sequences were found in the chromosome and a large plasmid of both H. mediterranei and Haloferax volcanii, and hybridization assays disclosed the presence of similar repeats in a second haloarchaeal genus, Haloarcula.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
What the sources say
- Not matchedcites [9]
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In the paper
“Northern blots hybridized with probes of the repeat region revealed multiple transcripts, suggesting that highly processed RNAs derived from the repeat arrays (Fig. 3).”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
What the sources say
- Not matchedcites [4]
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Together with the CRISPRassociated (Cas) proteins, they are the main constituents of the CRISPR-Cas systems that provide prokaryotes with acquired immunity and contribute other unrelated functions such as gene regulation.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
Strength:plain· not yet calibratedCausal:direct· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
None of the sources cited for this claim could be matched to a paper in Crossref, so there is nothing to check it against.
In the paper
“These signatures, today known as Protospacer Adjacent Motifs (PAMs), were afterwards shown to be a common feature in diverse CRISPR systems [22] where PAM recognition is a requisite for both spacer uptake and target interference [23].”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
What the sources say
- Not matchedcites [22]
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Although this genomic feature was serendipitously discovered in molecular biology studies”
§ The discovery of CRISPR in archaea and bacteria > Abstract
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In the paper
“We know now that CRISPR can acquire spacers from, and eventually interfere with, RNA [32] and/or DNA molecules, depending on the particular system.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
What the sources say
- Not matchedcites [32]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Strength:plain· not yet calibratedCausal:direct· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passesIt may state two separate claims as one.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“They represent a remarkable example of molecular memory that is hereditarily transmitted.”
§ The discovery of CRISPR in archaea and bacteria > Abstract
Load-bearingStrength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✗ Based: failsProbably not a substantial claim. The paper may give no reason why it holds.
In the paper
“Taken together, these findings strongly supported a connection between CRISPR and immunity against foreign DNA, most likely guided by CRISPR-RNA molecules.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
What the sources say
- Not matchedcites [11]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Tests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✓ Based: passesIt may state two separate claims as one.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Their existence proves that prokaryotic genomes are environment tuned.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
Strength:boosted· not yet calibratedCausal:direct· not yet calibratedTests✓ Asserted: passes✗ Checkable: fails✗ Load-bearing: fails✗ Based: failsProbably not a substantial claim. It may be too vague to check against evidence. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
In the paper
“Besides, target cleavage is not the only way CRISPR may act and roles beyond immunity, notably through regulation of gene expression [33], are played by specific systems.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
What the sources say
- Not matchedcites [33]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Strength:hedged· not yet calibratedCausal:conditional· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passesIt may state two separate claims as one.
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None of the sources cited for this claim could be matched to a paper in Crossref, so there is nothing to check it against.
In the paper
“Whereas regularly spaced repeats had not been seen before in archaea, similarly arranged structures had been reported in the chromosome of Gram-negative (Escherichia coli) [5] and Grampositive (Mycobacterium spp.) [6] bacteria.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
What the sources say
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In the paper
“not to mention the average 10% non-coding DNA [38] present in all these genomes.”
§ The discovery of CRISPR in archaea and bacteria > phenotypic properties in bacterial populations.
What the sources say
- Not matchedcites [38]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Clustered regularly interspaced short palindromic repeats, CRISPR for short, form arrays of up to several hundred units in the genome of many bacteria and archaea.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✓ Based: passesProbably not a substantial claim. The paper’s conclusions may not depend on it.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“It seems appropriate to remember here that the great motor of molecular biology during the XX th century, molecular cloning, was made possible by restriction endonucleases and plasmid vectors, both derived from serendipitous discoveries of prokaryotic cell biology features involved in self/nonself discrimination as well.”
§ The discovery of CRISPR in archaea and bacteria > phenotypic properties in bacterial populations.
Strength:plain· not yet calibratedCausal:direct· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✗ Load-bearing: fails✗ Based: failsProbably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“CRISPR-Cas are self/non-self discriminating systems found in prokaryotic cells.”
§ The discovery of CRISPR in archaea and bacteria > Abstract
Load-bearingStrength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes✓ Load-bearing: passes✗ Based: failsProbably not a substantial claim. The paper may give no reason why it holds.
In the paper
“Nonetheless, given that protospacers were also detected in chromosomal regions, a regulatory role for CRISPR was inferred, resembling the eukaryotic RNA interference (RNAi) mechanism [11].”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
What the sources say
- Not matchedcites [11]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Strength:hedged· not yet calibratedCausal:conditional· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passesIt may state two separate claims as one.
- Not matched
None of the sources cited for this claim could be matched to a paper in Crossref, so there is nothing to check it against.
In the paper
“There are orphan CRISPR arrays in prokaryotic genomes and viruses [34,35], as well as CRISPR-like stretches in eukaryotic viruses [36] and mitochondria [13], most of which are enigmatic regarding their activity or function.”
§ The discovery of CRISPR in archaea and bacteria > Accepted Article
What the sources say
- Not matchedcites [34]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- Not matchedcites [35]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- Not matchedcites [36]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- Not matchedcites [13]
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
Strength:plain· not yet calibratedTests✓ Asserted: passes✓ Checkable: passes? Load-bearing: unclear✓ Based: passesIt may state two separate claims as one.
- Not matched
The paper relies on this without support.
The four selected microorganisms (E. coli, Streptococcus pyogenes, Sulfolobus, and Methanothermobacter thermoautotrophicum) are representative of their respective prokaryotic groups such that common observations about their CRISPR loci apply to prokaryotes in general.
“Four microorganisms were selected, as representatives of their respective prokaryotic groups, for further analysis: E. coli (Gram-negative bacteria), Streptococcus pyogenes (Gram-positive bacteria), Sulfolobus (crenarchaea) and Methanothermobacter thermoautotrophicum (euryarchaea).”
“Hence, common observations related to their CRISPR loci would provide conclusions applying to the prokaryotes in general.”
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
Self-check results appear here once an independent check has confirmed them.
Cited works that were retracted
Works this paper cites that were later retracted, from the retraction notices publishers deposit. Major when the notice came out before this paper was published.
Cites a retracted work: 10.1038/nbt.3547
InfoThe cited work was retracted on 2017-07-26 (notice 10.1038/nbt0817-797a), not before this paper was published (2016-06-15).
Cited work 10.1038/nbt.3547 · retracted 2017-07-26 · notice 10.1038/nbt0817-797a · this paper published 2016-06-15
“10.1038/nbt.3547”
Citations
Cites
1 retracted
DNA-guided genome editing using the Natronobacterium gregoryi Argonaute
Gao, F., Shen, X. Z., Jiang, F., Wu, Y., & Han, C. (2016) · Nature Biotechnology · doi:10.1038/nbt.3547 · Cited by 170
RetractedCRISPR Provides Acquired Resistance Against Viruses in Prokaryotes
Barrangou, R., Fremaux, C., Deveau, H., Richards, M., Boyaval, P., Moineau, S., Romero, D. A., & Horvath, P. (2007) · Science · doi:10.1126/science.1138140 · Cited by 5,947
An updated evolutionary classification of CRISPR–Cas systems
Makarova, K. S., Wolf, Y. I., Alkhnbashi, O. S., Costa, F., Shah, S. A., Saunders, S. J., Barrangou, R., Brouns, S. J. J., Charpentier, E., Haft, D. H., et al. (2015) · Nature Reviews Microbiology · doi:10.1038/nrmicro3569 · Cited by 2,480
Self-citationSmall CRISPR RNAs Guide Antiviral Defense in Prokaryotes
Brouns, S. J. J., Jore, M. M., Lundgren, M., Westra, E. R., Slijkhuis, R. J. H., Snijders, A. P. L., Dickman, M. J., Makarova, K. S., Koonin, E. V., & van der Oost, J. (2008) · Science · doi:10.1126/science.1159689 · Cited by 2,460
Ishino, Y., Shinagawa, H., Makino, K., Amemura, M., & Nakata, A. (1987) · Journal of Bacteriology · doi:10.1128/jb.169.12.5429-5433.1987 · Cited by 2,421
The CRISPR/Cas bacterial immune system cleaves bacteriophage and plasmid DNA
Garneau, J. E., Dupuis, M.-È., Villion, M., Romero, D. A., Barrangou, R., Boyaval, P., Fremaux, C., Horvath, P., Magadán, A. H., & Moineau, S. (2010) · Nature · doi:10.1038/nature09523 · Cited by 2,336
Evolution and classification of the CRISPR–Cas systems
Makarova, K. S., Haft, D. H., Barrangou, R., Brouns, S. J. J., Charpentier, E., Horvath, P., Moineau, S., Mojica, F. J. M., Wolf, Y. I., Yakunin, A. F., et al. (2011) · Nature Reviews Microbiology · doi:10.1038/nrmicro2577 · Cited by 2,331
Self-citationComplete Genome Sequence of the Methanogenic Archaeon, Methanococcus jannaschii
Bult, C. J., White, O. R., Olsen, G. J., Zhou, L., Fleischmann, R. D., Sutton, G. G., Blake, J. A., Fitzgerald, L. M., Clayton, R. A., Gocayne, J. D., et al. (1996) · Science · doi:10.1126/science.273.5278.1058 · Cited by 2,086
Intervening Sequences of Regularly Spaced Prokaryotic Repeats Derive from Foreign Genetic Elements
Mojica, F. J. M., D�ez-Villase�or, C., Garc�a-Mart�nez, J., & Soria, E. (2005) · Journal of Molecular Evolution · doi:10.1007/s00239-004-0046-3 · Cited by 2,042
Self-citationIdentification of genes that are associated with DNA repeats in prokaryotes
Jansen, R., Embden, J. D. A. V., Gaastra, W., & Schouls, L. M. (2002) · Molecular Microbiology · doi:10.1046/j.1365-2958.2002.02839.x · Cited by 1,802
Flagged first, then by citations
1 of the 39 references couldn’t be matched to a known paper.
Cited by
Sorted by citations
CRISPR–Cas9 Structures and Mechanisms
Jiang, F., & Doudna, J. A. (2017) · Annual Review of Biophysics · doi:10.1146/annurev-biophys-062215-010822 · Cited by 2,029
Ishino, Y., Krupovic, M., & Forterre, P. (2018) · Journal of Bacteriology · doi:10.1128/jb.00580-17 · Cited by 558
Methodologies for Improving HDR Efficiency
Liu, M., Rehman, S., Tang, X., Gu, K., Fan, Q., Chen, D., & Ma, W. (2019) · Frontiers in Genetics · doi:10.3389/fgene.2018.00691 · Cited by 323
In vivo somatic cell base editing and prime editing
Newby, G. A., & Liu, D. R. (2021) · Molecular Therapy · doi:10.1016/j.ymthe.2021.09.002 · Cited by 193
Development of CRISPR-Cas systems for genome editing and beyond
Zhang, F. (2019) · Quarterly Reviews of Biophysics · doi:10.1017/s0033583519000052 · Cited by 188
Metadata
- Authors
- Mojica, F. J. M., & Rodriguez‐Valera, F.
- Affiliations
- University of Alicante (ES)
- Evolutionary Genomics Group Universidad Miguel Hernandez Alicante Spain
- Corresponding author
- Mojica, Francisco J. M.
- Venue
- The FEBS Journal
- Publisher
- Wiley
- Published
- 2016-06-15
- Volume
- 283
- Issue
- 17
- Pages
- 3162-3169
- ISSN
- 1742-464X (ISSN-L)
- 1742-4658
- OpenAlex
- W2397372517
- Cited by
- 207
- References
- 39
- Citations by year
- 2026: 10 · 2025: 24 · 2024: 27 · 2023: 22 · 2022: 36 · 2021: 26 · 2020: 19 · 2019: 11 · 2018: 18 · 2017: 11 · 2016: 3
- FWCI
- 1.24
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- Locations
- FEBS Journal (publishedVersion, other-oa)
- PubMed (publishedVersion)
- LA Referencia (Red Federada de Repositorios Institucionales de Publicaciones Científicas) (submittedVersion)
- Repositorio Institucional de la Universidad de Alicante (Universidad de Alicante) (submittedVersion)
- Funders
- European Commission (291815)
- Seventh Framework Programme
- Generalitat Valenciana
- Topics
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › CRISPR and Genetic Engineering
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Bacterial Genetics and Biotechnology
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Biochemical and Structural Characterization
- Keywords
- CRISPR-Cas, archaea, bacteria, self/non-self discrimination, molecular memory, adaptive immunity
- MeSH terms
- Archaea, Bacteria, Genome, Bacterial, Genome, Archaeal, Genomics, CRISPR-Cas Systems
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
A language model drew the claims from the paper on 2026-11-08, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).
A second model labelled each claim on 2026-11-08 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
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