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Biomedical subjects

D J Owen

Publications and source records attributed to D J Owen.

7 recordsLinked to original sources
PubMed1991

Phosphorylation at Thr167 is required for Schizosaccharomyces pombe p34cdc2 function.

Eukaryotic cell cycle progression requires the periodic activation and inactivation of a protein-serine/threonine kinase which in fission yeast is encoded by the cdc2+ gene. The activity of this gene product, p34cdc2, is controlled by numerous interactions with other proteins and by its phosphorylation state. In fission yeast, p34cdc2 is phosphorylated on two sites, one of which has been identified as Tyr15. Dephosphorylation of Tyr15 regulates the initiation of mitosis. To understand more completely the regulation of p34cdc2 kinase activity, we have identified the second site of phosphorylation as Thr167, a residue conserved amongst all p34cdc2 homologues. By analysing the phenotypes of cells expressing various position 167 mutations and performing in vitro experiments, we establish that Thr167 phosphorylation is required for p34cdc2 kinase activity at mitosis and is involved in the association of p34cdc2 with cyclin B. Dephosphorylation of Thr167 might also play a role in the exit from mitosis.

Amino Acid Sequence↗
PubMed1989

A role for nerve growth factor in collateral reinnervation from sensory nerves in the guinea pig.

We have investigated whether chronic nerve growth factor (NGF) depletion affects the development of a transmedian collateral reinnervation. The extent of transmedian innervation of the skin supplied by the left inferior alveolar nerve (IAN) was determined either immediately, 2 days or 7-9 weeks after sectioning and preventing regeneration of the contralateral IAN and in another group of animals left to recover for 7-9 weeks but also autoimmunised against NGF. Transmedian innervation was measured by recording the area from which a jaw-opening reflex could be evoked and by recording activity in the left IAN during mechanical and electrical stimulation of the skin. Nerve recording during electrical stimulation revealed extensive transmedian collateral reinnervation 7-9 weeks after denervation but this was prevented by NGF autoimmunisation. No change in transmedian innervation could be detected in any of the groups by nerve recording during mechanical stimulation and reflex responses revealed changes in the anaesthetic area which could not be attributed to collateral reinnervation. These results suggest that NGF plays an important role in collateral reinnervation from high-threshold sensory nerves.

Action Potentials↗
PubMed1986

Molecular cloning and characterization of sequences from the regulatory cluster of the Pseudomonas plasmid alk system.

Alkane oxidation functions encoded by the Pseudomonas plasmid CAM-OCT are positively regulated by one or more products of a locus designated alkR. To characterize this locus in greater detail, molecular cloning and restriction mapping of sequences covering the alkR region have been carried out in Escherichia coli, followed by mobilization to Pseudomonas recipients for analysis of genetic content. Inserts from Pseudomonas (CAM-OCT) strains were cloned into vectors pLAFR1, the pLAFR1::Tn7S derivative pXJS5403, and the transposon vector Tn3 delta 596. This has made it possible to: (1) construct a detailed restriction map of cloned fragments and the alkR region of CAM-OCT; (2) map insertion sites of the transposon Tn7S into alkR cistrons; and (3) analyze the ability of cloned sequences to complement or effect marker rescue of alkR nitrosoguanidine- and Tn7S-induced mutations. In addition, transcription of an alkB'-lacZ transcription fusion in the presence of a cloned 18.5 kb EcoRI alkR fragment and an inducer of the alk system confirmed that our cloned sequences contain functional alkR cistrons. The complementation/marker rescue results indicate that alkR is a complex locus and that the products of at least three cistrons are required for the complete AlkR+ phenotype. One of these cistrons is identified by mutations which alter a component of the inducer recognition system.

Alkanes↗
PubMed1985

Transfer of transposable drug-resistance elements Tn5, Tn7, and Tn76 to Azotobacter beijerinckii: use of plasmid RP4::Tn76 as a suicide vector.

Transposable elements Tn5, Tn7, and Tn76 were transferred to Azotobacter beijerinckii. Evidence was obtained for the transposition of Tn5 but cells of the majority of presumptive transposition isolates had abnormal morphologies and rapidly lost viability when subcultured. Data are presented that indicate that plasmid RP4::Tn76 behaves as a suicide vector upon transfer to this host, allowing the isolation of A. beijerinckii::Tn76 isolates at a high frequency. Nitrogen-fixing mutants and leucine and adenine auxotrophs were isolated from cultures in which the transposition of Tn76 occurred.

Azotobacter↗
PubMed1979

A comprehensive laboratory computer system working round the clock.

The special features of a laboratory computer system operated by laboratory staff around the clock are presented. The system provides registration of work, production of worksheets, on-line data acquisition and reporting results. The reasons for the special design features are discussed.

Allied Health Personnel↗