Given a passage, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

Example Input: Dihydrofolate reductase (DHFR) and thymidylate synthase (TS) are crucial enzymes in DNA synthesis. In alveolata both enzymes are expressed as one bifunctional enzyme.', "Loss of this essential enzyme activities after successful allelic assortment of knock out alleles yields an auxotrophic marker in ciliates. Here the cloning, characterisation and functional analysis of Tetrahymena thermophila's DHFR-TS is presented. A first aspect of the presented work relates to destruction of DHFR-TS enzyme function in an alveolate thereby causing an auxotrophy for thymidine. A second aspect is to knock in an expression cassette encoding for a foreign gene with subsequent expression of the target protein.
Example Output: Does the bifunctional dihydrofolate reductase thymidylate synthase of Tetrahymena thermophila provide a tool for molecular and biotechnology applications?

Example Input: A distinct velocity pattern represented by a "notch" is observed during the time interval between the end of the systolic and the onset of the early diastolic velocity wave on longitudinal myocardial velocity curve. The origin of the post-systolic velocity notch (PSN) has not been resolved.', 'The high frame rate color tissue Doppler imaging of the apical longitudinal axis was performed in 32 healthy subjects.', 'The time delays of the PSN onset at the posterior aortic wall (AW), the mid anteroseptal wall (MAS) and the posterior mitral annulus (MA) relatively to the anterior aortic annulus (AA) were found to be significantly longer than zero (5.1 ± 2.2, 6.0 ± 2.3, 6.8 ± 2.8 ms; p < 0.001). The amplitude was the highest at the AA when compared to the AW, the MAS and the MA (4.77 ± 1.28 vs. 2.88 ± 1.11, 2.15 ± 0.73, 2.44 ± 1.17 cm/s; p < 0.001). A second PSN spike was identifiable in 10/32 (31%) of the studied subjects at the AA. Of these, 9 (28%) exhibited a second PSN spike at the AW, 3 (9%) at the MAS and no one at the MA.
Example Output: Does the tissue Doppler imaging derived post-systolic velocity notch originate at the aortic annulus?

Example Input: Anorectal melanoma (AM) is a rare but highly malignant tumor, displaying histologic and immunohistochemical features very similar to cutaneous melanoma (CM). Because BRAF mutations were recently identified in the majority of CM and nevi, we investigated AM for BRAF mutations and mutations of NRAS , an additional component of the MAPK-signalling pathway.', 'DNA from formalin-fixed and paraffin-embedded AM was PCR amplified and sequenced.', "We detected BRAF mutations in 2 of 19 cases and NRAS mutations in none of the cases. Mutations in exon 15 of BRAF were present in only 1 tumor (1 of 19 cases). The A1800T base exchange represented a novel mutation and resulted in a K600N transition in an AM from a 96-year-old white man who presented with rectal bleeding and painful sitting of a few weeks' duration. The second positive AM case, a 69-year-old white man who presented with painless rectal bleeding and clinical symptoms of an intestinal constipation showed a novel missense mutation (C1327T leading to R443W conversion) in BRAF exon 11. None of the AM cases displayed the oncogenic V599E mutation preponderating in CM.
Example Output:
Do bRAF mutations distinguish anorectal from cutaneous melanoma at the molecular level?