DNA Sequencing with Chain-Terminating Inhibitors
Proceedings of the National Academy of Sciences, 1977 · paper · Biomedicine
Describes a method for determining DNA nucleotide sequences using chain-terminating dideoxy and arabinonucleoside analogues that stop DNA polymerase at specific bases. Applied to bacteriophage φX174 DNA, it is reported to be faster and more accurate than the plus and minus method.
Checked: PDF from europepmc.org, fetched 4 Oct 2026. Page numbers are those of that PDF.
0 findings
None that passed a second check.
6 minor (typos and the like; most checked by the judge only)
Reference or label Ref. 7 reads "Geider, K. (1974) Eur. J. Biochem. 27, 555-563."; the year looks inconsistent with volume 27.
- p. 5 Reference 7
Geider, K. (1974) Eur. J. Biochem. 27, 555-563.
Only the authors can say what is right here.
Judge's note: Rests on outside knowledge: volume 27 of Eur. J. Biochem. was published in 1972. The page 5 image confirms the entry is printed as quoted. Nothing in the files can confirm or refute the year.
Second check: another model agreed
Report a problem with this finding
Wording Introduction states the terminator:normal triphosphate ratio "for the arabinosyl derivatives about 5000", but the only arabinosyl mix given ("araC: 0.1 mM dGTP, 0.1 mM dTTP, 0.005 mM dCTP, 12.5 mM araCTP") has a ratio of 2500.
- p. 1 Introduction, end of 'Principle of the Method', right column
for the arabinosyl derivatives about 5000
- p. 2 Methods, Sequencing Procedure, araC mix
araC: 0.1 mM dGTP, 0.1 mM dTTP, 0.005 mM dCTP, 12.5 mM araCTP
- p. 2 Methods, araC mix
0.005 mM dCTP, 12.5
- p. 2 Sequencing Procedure, araC mix
0.005 mM dCTP, 12.5 mM araCTP
Only the authors can say what is right here.
Judge's note: Checked both crops. Page 1 prints 'For the dideoxy derivatives this ratio is about 100, and for the arabinosyl derivatives about 5000.' Page 2 prints 12.5 mM araCTP against 0.005 mM dCTP in the araC mix, which gives 2500. The dideoxy mixes match 100 exactly (e.g. ddG 0.5/0.005). Mix and sample are combined 2 µl + 2 µl, so dilution does not change the ratio. No araATP conditions are given, so the general figure for arabinosyl derivatives cannot be checked another way. The text says 'about', so this is a query for the authors: either the concentration or the ratio may be misprinted.
Second check: another model agreed
Report a problem with this finding
Wording Fig. 3 loop region is given as "3543–3550" in Results but "positions 3545–3550" in Discussion.
- p. 4 Results, right column, Fig. 3 description
There is difficulty in reading the sequence at 3543-3550
- p. 4 Discussion, right column, pile-ups
Another ex-ample is in Fig. 3 at positions 3545-3550.
- p. 4 Discussion
Another example is in Fig. 3 at positions 3545-3550
Judge's note: Page 4 image: Results (right column) gives 'difficulty in reading the sequence at 3543–3550 ... suggesting the presence of a looped structure'. Discussion gives 'Another example is in Fig. 3 at positions 3545–3550' for pile-ups. The two passages describe the same loop effect with different start positions. One may be the reading-difficulty region and the other the pile-up core, so either could be legitimate; the paper does not say which.
Second check: another model agreed
Report a problem with this finding
Typo "a mixture of fragments all having the same 5' and with ddT residues at the 3' ends" — 'and' should be 'end' (or the word 'end' is missing).
- p. 1 Principle of the Method, left column
all having the same 5' and with ddT residues at the 3' ends
- p. 1
a mixture of fragments all having the same 5' and with ddT residues at the 3' ends
Judge's note: The page 1 image prints '5′ and with ddT residues at the 3′ ends', so this is not an extraction artefact. The sentence is ungrammatical, and the parallel with '3′ ends' shows the intended word is 'end'.
Second check: none (judge only)
Report a problem with this finding
Typo "When this technique is used the products are cut with a restriction enzyme as above, difficulties arise..." lacks a conjunction (e.g. 'and' or 'in which') after 'used'.
- p. 4 Results, left column, paragraph on second restriction site
When this technique is used the products are cut with a re-striction enzyme as above, difficulties arise
Judge's note: Page 4 image (left column) prints the sentence exactly as quoted. It reads as two clauses run together. This is a minor wording issue and the meaning can be recovered.
Second check: none (judge only)
Report a problem with this finding
Typo "when the priming is carried in opposite directions" is missing 'out' ('carried out in opposite directions').
- p. 4 Discussion, pile-ups paragraph
when the priming is carried in opposite direc-
Judge's note: Page 4 image (Discussion, right column) prints 'when the priming is carried in opposite directions along the DNA'. The word 'out' is missing.
Second check: none (judge only)