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Biomedical subjects

A H Fielding

Publications and source records attributed to A H Fielding.

9 recordsLinked to original sources
PubMed1987

Expert systems: frames, rules or logic for species identification?

The role of expert systems in species identification, with particular reference to the problems posed by damaged specimens and inexperienced taxonomists, is discussed. Of the three main types of expert systems available, the frame-based system is shown to provide the most appropriate model for a taxonomic expert system rather than a logic- or rule-based system. The advantages of an expert system over other computer-aided methods of identification are considered. A rule-based system requires the original knowledge (species descriptions) to be structured into rules, whereas a frame-based system can store the generic and specific descriptions in a series of frames. The frames fall into a hierarchy which closely resembles the taxonomic hierarchy, and down which information can be inherited. Two aspects of frame-based systems considered are the use of probabilities in identification, and the optimum structure of the knowledge base. The conventional use of probabilities is to provide an indication of the correctness of the result. However, in some studies involving the identification of many specimens, the speed of identification may be increased (with a reduction in accuracy) if identifications are made to a predetermined probability level. Although frames allow accurate representation of the taxonomic hierarchy, a semantic net, incorporating structures of the organism and/or details of the habitat may result in a more efficient expert system.

Animals↗
PubMed1986

A rapid computer technique for analysing molecular interactions.

A rapid method for analysing enzyme-substrate interactions using a discriminant analysis program is described. This technique identifies the structural features of substrate molecules which are important in determining metabolic activity. Two model systems, nucleoside diphosphatase activity of Golgi membranes and the interaction of yeast hexokinase with a range of D-sugars, are used as illustrations of the technique. The conclusions from both models are consistent with those previously obtained from analytical techniques.

Acid Anhydride Hydrolases↗
PubMed1984

Cloning of genes involved in pathogenicity of Xanthomonas campestris pv. campestris using the broad host range cosmid pLAFR1.

A genomic library was prepared in Escherichia coli from DNA of wild-type Xanthomonas campestris pv. campestris (aetiological agent of crucifer black rot), partially digested with endonuclease EcoRI, using the mobilisable broad host range cosmid vector pLAFR1. Recombinant plasmids contained inserts ranging in size from 19.1 to 32.3 kb (mean 26.6). Certain of the clones complemented E. coli auxotrophic markers. Using the narrow host range plasmid pRK2013 as a helper the pooled recombinant plasmids were transferred conjugally to X. c. campestris mutants, and clones were identified which restored yellow pigmentation to white mutants, prototrophy to amino acid auxotrophs and pathogenicity towards turnip plants to two non-pathogenic mutants. The lesion in one mutant (8288, complemented by the plasmid pIJ3000) is unknown. However mutant 8237 is defective in production of extracellular protease and polygalacturonate lyase and restoration of pathogenicity by complementation with the plasmid pIJ3020 concomitantly restored both enzyme levels to wild-type values.

Journal Article↗
PubMed1983

The use of cluster analysis in determining possible enzyme-substrate interactions with reference to nucleoside diphosphatase activity of Golgi membranes.

The relative effectiveness of deoxyribonucleoside diphosphates, ribonucleoside diphosphates and phosphorylated B vitamins as substrates of the nucleoside diphosphatase of Golgi membranes have been determined. The substrates have been classified by cluster analysis. These findings suggest that a base ketone group and the 3'-OH of the substrates are important in promoting catalytic effectiveness, possibly by promoting hydrogen bonding during enzyme-substrate complex formation.

Acid Anhydride Hydrolases↗