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A Healey

Publications and source records attributed to A Healey.

24 records · Page 2Linked to original sources
PubMed1987

Giardia intestinalis antigens expressed in Escherichia coli.

cDNA and genomic DNA of Giardia intestinalis have been cloned in pUC vectors and used to express Giardia antigens in Escherichia coli. Several expression libraries have been produced and positive clones identified by immuno-colony assays with antisera raised against whole parasites and partially purified antigen(s). Those clones which express G. intestinalis antigens have been used to raise antisera in mice and the antisera used in immunofluorescence assays. The proteins expressed by the clones have been shown to represent a 32 kDa protein of the flagellae and axonemes, a protein associated with the spiral part of the ventral disc, proteins covering the surface of the trophozoite or associated with the coat, and other proteins associated with axonemes of posterolateral flagellae, kinetosomes and funis, and the anterolateral axonemes. mRNA was purified from G. intestinalis and translated in a cell free lysate. A rabbit antiserum raised against trophozoites immunoprecipitated several translation products while an antiserum raised against a purified 32 kDa protein only immunoprecipitated this protein. G. intestinalis rRNA subunits also were examined in the course of mRNA purification. Two rRNA species were evident, the small rRNA and the post-transcriptionally processed large rRNA.

Animals↗
PubMed1987

Rapid and efficient method for cloning of blunt-ended DNA fragments.

We describe a system to generate cDNA or genomic libraries from DNA segments that have blunt termini. Background and rearrangement levels are low, but efficiencies are high and the procedural times very short. T4 ligase in the presence of polyethylene glycol produces high Mr oligomers of vector and insert. These concatemers are reduced to vector-insert monomers at a high frequency by subsequent cleavage with a restriction endonuclease, which recognises the insert rarely, if at all, and the vector once. The monomers are recircularised under standard ligation conditions prior to transformation. Thus insertion conditions are optimised independently of those for recircularisation. All reading frames for expression libraries are generated by short BAL 31 cleavage followed by the blunt-end cloning procedure. Similarly, genomic expression libraries can be made by BAL 31 or mung-bean nuclease treatment after cleavage with DNase I is the presence of Mn2+. The technique is suitable for any DNA segment that is blunt-ended or can be made so. When the vector is treated with alkaline phosphatase, recombinants are generated at a frequency greater than 90% and have single inserts. Yields are 3-5 X 10(6) colony-forming units per micrograms of insert.

Cloning, Molecular↗
PubMedDate not supplied

Diagnosis of Plasmodium vivax malaria using a specific deoxyribonucleic acid probe.

A deoxyribonucleic acid (DNA) probe which specifically distinguishes Plasmodium vivax from P. falciparum malaria has been derived from a P. vivax genomic DNA library. This probe, VPL101, consists of 3.2 kilobase pairs and does not hybridize with up to 6 micrograms of human or P. falciparum DNA. VPL101 contains at least two copies of a 205 base pair repeat sequence. The subcloned repeat probe, VPL101/5, reacted with 73 of 76 microscopically diagnosed P. vivax samples but not with any of 17 human DNA samples or any of 8 P. falciparum DNA samples from cultured parasites. It was possible to detect P. vivax in mixed infections in which only P. falciparum parasites were identifiable by microscopy. This P. vivax DNA probe provides a useful epidemiological tool for malaria control programmes.

Animals↗
PubMedDate not supplied

A new rDNA repeat unit in human Giardia.

The rDNA repeat unit from a new human Giardia duodenalis strain shows significant differences from the previously reported G. duodenalis rDNA repeat. Twelve base-pair changes occurred in 490 bp of the SSrRNA gene and new restriction enzyme sites occurred in the LSrRNA gene. The overall length of the rRNA genes is the same but the spacer is 76 bp longer than previously reported. A boundary within the spacers of the two different rDNA units divides a region of 50% homology near the LSrRNA gene from a region of 80% homology toward the SSrRNA gene. This boundary region includes two copies of a 78 bp repeat.

Animals↗