Biomedical subjects

L Theodor

Publications and source records attributed to L Theodor.

21 records · Page 2Linked to original sources

PubMed1985

P31, a mammalian housekeeping protein encoded by a multigene family containing a high proportion of pseudogenes.

The primary structure of P31, a 13.300 kDa mammalian 'housekeeping' protein, was deduced from the nucleotide sequence of a rat recombinant cDNA clone. The P31 mRNA has 950 nucleotides and codes for a protein of 121 amino acids. This mRNA is present in several mouse tissues and in other mammals. Nuclei of rapidly growing cells contain mature P31 mRNA and a distinctive set of larger transcripts. P31 is encoded by a multigene family. Five members of the family were isolated from a mouse genomic library and restriction mapping and S1 nuclease analysis of four of them (P31-4, P31-12, P31-13 and P31-14) suggest that they are processed genes. The very low homology of the fifth (P31-8) with respect to the corresponding cDNA sequence indicates that it is a pseudogene. Although the features of the mRNA and the genes encoding P31 exhibit extensive similarity with those of ribosomal proteins, neither the identity nor the biological function of the protein has yet been determined.

Amino Acid Sequence↗

PubMed1983

The relationship between contextual facilitation and depth of processing.

Two experiments examined how depth of processing on a contextual priming item affects (a) the amount of priming obtained in the processing of a target item in a lexical decision task (LDT) and (b) subsequent episodic memory for the prime and target items. Experiment 1, in which prime and target items were presented sequentially, yielded three main results: (a) The magnitude of the priming effect, measured by the difference between lexical decision times to word targets preceded by related and unrelated primes, increased as the depth of prime processing increased. (b) In an unexpected postsession recognition test, episodic memory for a prime was dependent on the depth to which it had been processed, whereas memory for a target was unaffected by the depth of processing that had occurred on its prime. (c) Episodic memory for both primes and targets was greater when they had appeared in related pairs rather than unrelated pairs in the LDT. However, unlike immediate contextual priming, the magnitude of the semantic relatedness effect in episodic recognition was not affected by level of processing. In Experiment 2 a two-word LDT was used in which a yes response was made only if two simultaneously presented letter strings were both words. Depth of processing was varied by using different types of nonword distractors: pronounceable nonwords, random letter strings, or strings of Xs. As in Experiment 1, priming was greater and episodic recognition was better, the deeper the level of processing that occurred in the LDT. Similarly, episodic recognition memory was greater for items that had appeared in related pairs in the LDT. Although these data suggest that similar processes modulate both contextual priming effects and episodic recognition, the dissociation in some conditions between the occurrence of contextual priming in the LDT and later relatedness effects in episodic recognition indicate that the underlying mechanisms are not identical.

Cognition↗

PubMedDate not supplied

Could the 185delAG BRCA1 mutation be an ancient Jewish mutation?

A predominant mutation within the BRCA1 predisposition gene, 185delAG, has been detected in about 1% of the Ashkenazi population, considered a high-risk group for breast and ovarian cancers. We examined 639 unrelated healthy Jews of Iraqi extraction, a presumed low-risk group, for the existence of this mutation. Three individuals were identified as 185delAG mutation carriers, and haplotype analysis of the Iraqi mutation carriers revealed that 2 of the Iraqis shared a common haplotype with 6 Ashkenazi mutation carriers, and 1 had a haplotype which differed by a single marker. This study suggests that the BRCA1 185delAG mutation also occurs in populations considered at low-risk for breast and ovarian cancers, and that it might have occurred prior to the dispersion of the Jewish people in the Diaspora, at least at the time of Christ.

Adult↗