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Biomedical subjects

A R Dunn

Publications and source records attributed to A R Dunn.

88 records · Page 5Linked to original sources
PubMed1979

Nucleotide sequence analysis of the leader segments in a cloned copy of adenovirus 2 fiber mRNA.

Fiber mRNA of adenovirus 2 has been used as a template for RNA-dependent DNA polymerase. The resulting cDNA/RNA hybrids have been inserted at the Pst I site of the plasmid vector pBR322 after A:T tailing. One recombinant plasmid, pJAW 43, has been characterized in detail and shown to contain sequences from the main body of fiber mRNA, the three leaders common to most late adenoviral mRNAs and a fourth leader found in some species of fiber mRNA. The complete DNA sequence of the leader region has been determined and does not contain the initiation codon AUG, although this codon does occur immediately downstream from the junction between the fourth leader and the main body of the fiber mRNA. The first leader (map coordinate 16.6) is 41 nucleotides long, the second (from 19.6) is 71 nucleotides, the third (from 26.6) is 88 nucleotides and the fourth (from 78.5) is 181 nucleotides. The location of junctions between viral leaders and intervening sequences has been determined by reference, where possible, to sequences of the adenovirus 2 genome. Although the presence of short repeated sequences at the boundaries of intervening sequences and leaders makes it impossible to locate the splice point unambiguously, all of the leader-intervening sequence junctions can be arranged to stress a common feature--the presence of the dinucleotides GT and AG at the 5' and 3' ends, respectively, of the intervening sequences. This prototype sequence, which has also been recognized at or near the splice points in other eucaryotic systems, is possibly part of a larger unit which serves as a recognition site for specific excision-ligation events that ultimately lead to the production of mature mRNAs.

Adenoviruses, Human↗
PubMed1977

A novel method to map transcripts: evidence for homology between an adenovirus mRNA and discrete multiple regions of the viral genome.

A method has been devised which permits mapping of transcripts by a two-step hybridization procedure (sandwich hybridization). RNA extracted from cells infected with an adenovirus-SV40 hybrid (Ad2+ND1) was hybridized to restriction endonuclease fragments of adenovirus type 2 (Ad2) DNA immobilized on nitrocellulose filters. RNAs containing both Ad2 and SV40 sequences formed duplexes through their Ad2 sequences, leaving their SV40 sequences as protruding tails. Annealing with 32P-labeled SV40 DNA caused these tails to become labeled, permitting autoradiographic identification of the sequences of Ad2 DNA which are homologous to the RNA. The high sensitivity of this technique, achieved through the use of 32P-labeled RNA of high specific activity, has led to the observation that hybridization of Ad2+ND1 RNA occurs at several locations on the Ad2 genome, in addition to the expected sites of hybridization proximal to the SV40 insertion.

Adenoviruses, Human↗
PubMedDate not supplied

Molecular cloning of cDNA encoding a murine haematopoietic growth regulator, granulocyte-macrophage colony stimulating factor.

DNA clones specifying the murine granulocyte-macrophage colony stimulating factor have been isolated. This haematopoietic growth factor is encoded by a unique gene specifying a messenger RNA of 1,200 nucleotides and a polypeptide of 118 amino acids. It bears no structural similarity to the functionally related factor, interleukin-3, described recently.

Amino Acid Sequence↗
PubMedDate not supplied

Disruption of learned and spontaneous alternation in the rat by trimethyltin: chronic effects.

Trimethyltin (TMT) is a known neurotoxin which produces behavioral anomalies including hyperactivity, aggressiveness, perseveration, and learning deficits. These dysfunctions appear to be related to a severe loss of neurons in the hippocampal formation of the TMT-treated rat. In order to assess the effect of TMT exposure upon spontaneous and learned alternation, male Long-Evans rats were pretested for reinforced spontaneous alternation and then treated with either 7 mg/kg of TMT [( CH3]3SnCl) or the 0.9% NaCl vehicle. After treatment these groups were further subdivided and half of each group was tested in a "T" maze for reinforced spontaneous alternation while the remainder was tested for learned alternation. The TMT-treated rats uniformly ran faster on the second choice of reinforced spontaneous alternation tests than did controls. In addition, the TMT-treated rats made fewer alternations than controls, regardless of whether or not only successful alternations were being reinforced. These results are discussed in light of the known neurobehavioral consequences of TMT exposure.

Animals↗