Prostaglandin dehydrogenase activity of purified rat liver 3 alpha-hydroxysteroid dehydrogenase

Homogeneous 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSD) from rat liver cytosol displays 9, 11, and 15-hydroxyprostaglandin dehydrogenase activity. Using [14C]-PGF2 alpha as substrate the products of this reaction were separated by TLC and identified by autoradiography as PGE2 and PGB2. The purified enzyme catalyzes this reaction at a rate 200 times faster than cytosol. This corresponds to the rate enhancement observed when the enzyme is purified from cytosol using androsterone (a 3 alpha-hydroxysteroid) as substrate and suggests that it may represent a major 9-hydroxyprostaglandin dehydrogenase in this tissue. Although the 3 alpha-HSD has many properties in common with the 9-hydroxyprostaglandin dehydrogenase of rat kidney, rat kidney contains no protein that is immunodetectable with polyclonal antibody raised against the purified 3 alpha-HSD.     

The isolation,characterization and application in the Triticeae of a set of wheat RFLP probes identifying each homoeologous chromosome arm

Summary To investigate the use of RFLP analysis in the Triticeae, a set of low copy number probes has been isolated from a wheat cDNA library. The probes identify each of the 14 homoeologous chromosome arms of wheat as determined by analysis of DNA fragments hybridizing to the probes in aneuploid lines of Chinese Spring. These probes can be used in RFLP analyses both for the assignment of homoeology of alien chromosomes or arms added to wheat, and for the determination of chromosome dosage in wheat aneuploids. Different chromosomes from various Triticeae species can therefore be followed in a wheat genetic background using a single technique. The potential uses of the set in facilitating the transfer of alien segments into wheat are outlined.     

RFLP-based genetic maps of wheat homoeologous group 7 chromosomes

Summary Restriction fragment length polymorphism (RFLP) mapping was attempted using 18 cDNA clones, 14 anonymous and 4 of known function, which had been shown to have homologous DNA sequences on the group 7 chromosomes of wheat. The loci identified by these probes have been mapped on one or more chromosomes in this homoeologous group using linkage data derived from various F₂, random inbred, doubled haploid and single chromosome recombinant populations. The maps also include three isozyme loci, five disease resistance loci, two anthocyanin pigment loci and a vernalisation response locus. The mapping data have been used to determine the extent of map co-linearity over the A, B and D genomes, the degree of RFLP variability in the three genomes and the relative efficiency of various restriction enzymes in detecting RFLPs in wheat. The strategy for future mapping in wheat, particularly the use of alien genomes or segments, such as that from Aegilops ventricosa used here, is discussed.     

Cell lines established by a temperature-sensitive simian virus 40 large-T-antigen gene are growth restricted at the nonpermissive temperature.

The thermolabile large T antigen, encoded by the simian virus 40 early-region mutant tsA58, was used to establish clonal cell lines derived from rat embryo fibroblasts. These cell lines grew continuously at the permissive temperature but upon shift-up to the nonpermissive temperature showed rapidly arrested growth. The growth arrest occurred in either the G1 or G2 phase of the cell cycle. After growth arrest, the cells remained metabolically active as assayed by general protein synthesis and the ability to exclude trypan blue. The inability of these cell lines to divide at the nonpermissive temperature was not readily complemented by the exogenous introduction of other nuclear oncogenes. This finding suggests that either these genes establish cells via different pathways or that immortalization by one oncogene results in a finely balanced cellular state which cannot be adequately complemented by another establishment gene.     

Monospecific antibodies against a synthetic peptide predicted from the alpha-3 nicotinic receptor cDNA inhibit binding of [3H]nicotine to rat brain nicotinic cholinergic receptor

Polyclonal antibodies were raised against a synthetic decapeptide (designated S3) predicted from a segment of the alpha-3 subunit cDNA (amino acid residues 130-139) encoding the rat brain nicotinic cholinergic receptor. This segment was selected because it may be proximate to the nicotine/acetylcholine-binding site of the receptor (1). By radioligand binding assays and sucrose density gradient centrifugation, these monospecific antibodies were shown to inhibit the binding of [3H]nicotine to both the large molecular weight rat brain receptor (240 kDa) and to an SDS-disaggregated nicotine-binding subunit species (80 kDa), in a dose-dependent manner. The neutralizing effect of the anti-S3 antibodies supports the view that this region of the protein is closely related to the agonist binding site.     

The occurrence of polyenoic very long chain fatty acids with greater than 32 carbon atoms in molecular species of phosphatidylcholine in normal and peroxisome-deficient (Zellweger''s syndrome) brain.

The n-6 tetra- and pentaenoic fatty acids with carbon chain lengths greater than 32 found in normal brain are located predominantly in a separable species of phosphatidylcholine. A similar phospholipid is found in increased amounts in the brain of peroxisome-deficient (Zellweger's syndrome) patients, but the fatty acid composition differs in that penta- and hexaenoic derivatives predominate. Our data strongly suggest that the polyenoic very long chain fatty acids are confined to the sn-1 position of the glycerol moiety, while the sn-2 position is enriched in saturated, monounsaturated and polyunsaturated fatty acids with less than 24 carbon atoms. It is postulated that these unusual molecular species of phosphatidylcholine may play some, as yet undefined, role in brain physiology.