Biomedical subjects

M J Spence

Publications and source records attributed to M J Spence.

21 records · Page 2Linked to original sources

PubMed1995

Analysis of mutations in alleles of the fur gene from an endoprotease-deficient Chinese hamster ovary cell strain.

RPE.40 mutant cells differ from wild-type Chinese hamster ovary (CHO-K1) cells in their increased resistance to Pseudomonas exotoxin A and their inability to process the insulin proreceptor and certain viral envelope proproteins. Northern analysis revealed that RPE.40 cells maintained a substantially lower steady-state level of 4.0 kb fur mRNA than did CHO-K1 cells. Analysis of fur cDNAs showed that RPE.40 cells were diploid at the fur locus, and RPE.40 cells had a Cys (TGC) to Tyr (TAC) mutation in codon 196 of one allele (allele I). Approximately 25-30% of the CHO-K1 cells were also heterozygous (Tyr/Cys) at codon 196, and pre-mRNAs transcribed from the second allele (allele II) in RPE.40 cells were defectively spliced. All other pre-mRNAs were correctly spliced. Rapid turnover of defectively spliced transcripts may account for the reduced steady-state level of fur mRNA observed in RPE.40 cells. Our results provide a mechanistic basis for the endoprotease-deficient phenotype of RPE.40 cells.

Alleles↗

PubMed1991

The structure of a Phaseolus vulgaris cDNA encoding the iron storage protein ferritin.

A cDNA containing the entire coding region for the iron storage protein ferritin has been isolated from the French bean plant, Phaseolus vulgaris L. cv. Tendergreen. Ferritin protein was purified from young leaves and shoot meristem tissue and used to raise antisera in mice. A lambda gt11 cDNA library was constructed from seed-derived poly(A)+ RNA, and screened with the mouse anti-ferritin serum. A 1.2 kb immunopositive phage DNA insert was isolated and sequenced. The derived amino acid sequence shows substantial similarity with other ferritin sequences. The 5' untranslated region contains two out-of-frame AUG codons, a region of extreme pyrimidine composition bias and potentially stable secondary structure.

Amino Acid Sequence↗

PubMed1984

Voice recognition: effects of orienting task, and a test of blind versus sighted listeners.

Three experiments on memory for unfamiliar voices are reported. In the first two experiments, the type of encoding was manipulated by orienting tasks. In each study, one group rated the pleasantness of the voices, another group made judgments of pitch, and a third group performed no orienting task. Recognition memory was not correlated with encoding condition in either experiment. In Experiment 2, voice memory was better when the message remained constant from study to test than when it was changed. In Experiment 3, a group of blind adults was tested with no orienting task. The blind subjects' memory was equivalent to that of the appropriate sighted group of Experiment 2. It is proposed that voices represent a psychologically unitary stimulus that cannot be encoded with differing degrees of elaboration; therefore, voices are not sensitive to orienting tasks in the way that other classes of events, such as words and faces, are.

Adult↗