Biomedical subjects

S J Clarke

Publications and source records attributed to S J Clarke.

57 records · Page 4Linked to original sources

PubMed1973

Close linkage of the genes serC (for phosphohydroxy pyruvate transaminase) and serS (for seryl-transfer ribonucleic acid synthetase) in Escherichia coli K-12.

Escherichia coli strain K28, isolated after nitrosoguanidine mutagenesis, was found to be auxotrophic for serine. It was also temperature sensitive for growth as a result of producing an altered seryl-transfer ribonucleic acid (tRNA) synthetase (EC 6.1.1.11, l-serine: tRNA ligase [AMP]). The auxotrophy was caused by a mutation in the structural gene for phosphohydroxy-pyruvate transaminase (serC), which was distinct from, but closely linked to, the structural gene for seryl-tRNA synthetase (serS). We conclude that the relevant genes are in the order gal-serS-serC-aroA.

Amino Acyl-tRNA Synthetases↗

PubMed1973

Isolation and characterization of a regulatory mutant of an aminoacyl-transfer ribonucleic acid synthetase in Escherichia coli K-12.

From Escherichia coli strain K28, which is temperature sensitive for growth because of a mutation in its seryl-transfer ribonucleic acid (tRNA) synthetase gene (serS), temperature-resistant mutants were selected which were found to have a fivefold higher level of seryl-tRNA synthetase than the parent strain. The "high-level" character was found to be genetically stable and is due to a mutation in a locus denoted serO. This locus was found to be very closely linked to serS on the genetic map, and the relative gene order was concluded to be serS-serO-serC. In a serO(-) strain, the normal dependence of seryl-tRNA synthetase (SerRS) activity on changes of exogenous serine concentration was not observed. In a stable heterozygous merodiploid, the serO(-) mutation is still expressed, i.e., it is cis dominant. These results strongly suggest that serO is an operator site involved in the control of the serS gene.

Amino Acyl-tRNA Synthetases↗

PubMedDate not supplied

Recurrence of aneurysmal bone cyst of the fourth metatarsal.

Aneurysmal bone cyst is a benign solitary lesion of unknown etiology. Its radiographic and histologic appearance can overlap with those tumors of malignant origin. It is imperative that clinical data, radiographs, and operative and pathological findings be correlated to ensure an accurate diagnosis. Aneurysmal bone cysts occur only 7% of the time in the foot. Recurrence rates are reported to be less than 12%. A case report of recurrence of aneurysmal bone cyst in the foot is reviewed, in addition to the etiology, differential diagnosis, and treatment alternatives.

Adolescent↗