PubMed Health⌕ Search

Biomedical subjects

A D Delaney

Publications and source records attributed to A D Delaney.

10 recordsLinked to original sources
PubMed1990

Characterization and organization of DNA sequences adjacent to the human telomere associated repeat (TTAGGG)n.

We present a strategy for the cloning of DNA sequences adjacent to the tandemly repeated DNA sequence (TTAGGG)n. Sequence analysis of 14 independently isolated clones revealed the presence of non-repetitive sequences immediately adjacent to or flanked by blocks of the simple repeat (TTAGGG)n. In addition, we provide sequence information on two previously undescribed tandemly repeated sequences, including a 9 bp repeat and a modification of the (TTAGGG)n repeat. Using different mapping approaches six sub-clones, free of the TTAGGG repeat, were assigned to a single human chromosome. Moreover, in situ hybridization mapped one of these subclones, G2 - 1H, definitively to the telomeric band on chromosome 4q. However, Bal 31 insensitivity suggests a location in a more subterminal region. All the (TTAGGG)n-adjacent unique sequences tested are highly conserved among primates but are not present in other mammalian species. Identification and mapping of TTAGGG-adjacent sequences will provide a refined insight into the genomic organization of the (TTAGGG)n repeat. The isolation of chromosome specific TTAGGG-adjacent sequences from subtelomeric regions of all human chromosomes will serve as important end points for the genetic maps and will be useful for the molecular characterization of chromosomal rearrangements involving telomeres.

Base Sequence↗
PubMed1985

Drosophila melanogaster tRNAVal3b genes and their allogenes.

Drosophila tRNAVal3b genes have been analyzed with respect to their nucleotide sequence and in vitro transcription efficiency. Plasmid pDt78R contains a single tRNA gene derived from the major tRNAVal3b gene cluster at chromosome band 84D. Its sequence corresponds to that of the tRNAVal3b. Two other plasmids, pDt41R and pDt48, each contain a tRNAVal3b-like gene from the minor tRNAVal3b gene cluster at chromosome bands 90BC. They contain the expected CAC anticodon, but their sequence differs from the tRNA at four positions. In homologous cell-free extracts, the tRNAVal3b variant genes in pDt41R and pDt48 are transcribed an order of magnitude more efficiently than the tRNAVal3b gene in pDt78R. However, the variant genes do not appear to contribute significantly to the in vivo tRNA pool [Larsen et al.: Mol. Gen. Genet. 185 (1982) 390-396]. We propose the term allogenes to describe families of related DNA sequences that may code for variant forms of a standard tRNA isoaccepting species.

Chromosome Mapping↗
PubMed1979

Isolation and characterization of recombinant DNA plasmids carrying Drosophila tRNA genes.

Recombinant plasmids carrying Drosophila melanogaster tRNA genes were constructed by ligation of HindIII-cleaved Drosophila DNA to HindIII cut pBR322 DNA. 90 clones were isolated that contained genes for one or more of eleven tRNAs. 43 of the plasmids were characterized by a number of methods: restriction nuclease digestion; agarose gel electrophoresis; hybridization with individual, purified, 125I-labelled Drosophila tRNA molecules and in situ hybridization to Drosophila chromosomes. The results show that several different tRNA genes have been isolated which code for single, specific isoacceptors. The DNAs from 8 plasmids each hybridize to single sites on Drosophila polytene chromosomes. In addition, the data show examples of two different plasmids hybridizing to different loci coding for the same tRNA; this means that we have isolated representatives of tRNA genes which map at widely separated points on the Drosophila genome.

Animals↗
PubMed1979

The nucleotide sequence of the initiator tRNA from Drosophila melanogaster.

The nucleotide sequence of Drosophila melanogaster methionine tRNAi was determined to be: pA-G-C-A-G-A-G-U-m1G-m2G-C-G-C-A-G-U-G-G-A-A-G-C-G-U-m2G-C-U-G-G-G-C-C-C-A-U-t6A-A-C-C-C-A-G-A-G-m7G-D-m5C-C-C-G-A-G-G-A-U-C-G-m1A-A-A-C-C-U-U-G-C-U-C-U-G-C-U-A-C-C-A(OH). It differs from vertebrate initiator tRNAs in only 6 out of 75 positions.

Animals↗
PubMed1978

Synthesis of 125I-labeled N-3-(4-hydroxyphenyl)propionyl aminoacyl transfer ribonucleic acids.

A method for the isolation and labeling to high specific radioactivity of individual isoaccepting tRNAs is described. After blocking reactive minor bases by acetylation and iodination of the crude tRNA, a single family of isoacceptors was aminoacylated. Individual isoacceptors were separated by chromatography on RPC-5 and then acylated with the 3-(4-hydroxyphenyl)propionyl ester of N-hydroxysuccinimide. The product was purified by chromatography on BD-cellulose and RPC-5. This derivatized tRNA was then iodinated with 125I- and Chloramine-T to give a product containing between 5 X 10(7) and 3 X 10(8) dpm/microgram. The suitability of such labeled tRNAs for hybridization to homologous DNA in solution and cytological preparations of chromosomes is discussed with particular reference to Drosophila melanogaster.

Chromatography, Gel↗
PubMed1978

Acetylation of chromosome squashes of Drosophila melanogaster decreases the background in autoradiographs from hybridization with [125I]-labeled RNA.

DNA in prepared chromosomes from the larval salivary glands of Drosophila melanogaster was hybridized with [125I]-labeled 5S and tRNA from the same organism. Autoradiography revealed that radioactivity was frequently bound to all regions of the slides, masking labeling of the chromosomes. Acetylation of the preparations before hybridization prevented the formation of this background and revealed the specific chromosomal sites.

Acetylation↗
PubMed1976

Nucleotide clusters in deoxyribonucleic acids. XIII. Sequence analysis of the longer unique pyrimidine oligonucleotides of bacteriophage S13 DNA by a method using unlabeled atarting oligonucleotides.

A method has been designed for sequence analysis of unlabeled oligodeoxynucleotides of chain length up to 20 nucleotides with no restriction on base composition. The unlabeled oligonucleotide preparation, is partially degraded with spleen exonuclease to give a series of products each differing in size by one nucleotide. The oligonucleotides in the digest are 5'-32 P terminally labeled with [psi-32] P ATP and T4 polynucleotide kinase, the excess ATP removed by chromatography on Sephadex G-25 then the oligonucleotides fractionated according to change length on DEAE-Sephadex. Each isostich fraction is analyzed for base composition and the nucleotide at the 5' terminus determined by its 32P label, resulting in direct read off of the sequence up to the penultimate 3'- terminal nucleotide. The 3'-terminal dinucleotide is analyzed by DEAE-cellulose chromatography of the Sephadex G-25 dinucleotide fraction. The method has been demonstrated by sequence analysis of the unique longer pyrimidine oligonucleotides C5T6, C2T8, C6T4 and C6T3 from S13 DNA. The sequences have extensive internal sequence homology.

Base Sequence↗
PubMed1976

Nucleotide clusters in deoxyribonucleic acids. Comparison of the sequences of the large pyrimidine oligonucleotides of bacteriophages S13 and phiX174 deoxyribonucleic acids.

The large pyrimidine oligonucleotides from the DNAs of the two related bacteriophages phiX174 and S13 have been sequenced. The largest pyrimidine oligonucleotide present is unique to S13 DNA and is the undecanucleotide C5T6, sequence C-T-T-C-C-T-C-T-T-C-T. Considerable sequence homology has been found between the pyrimidine oligonucleotides of the two phage DNAs. Out of 14 oligonucleotide sequences from S13 DNA (120 bases) at least ten are identical with sequences of oligonucleotides from phiX174 DNA (92 bases) and two are closely related (17 bases), the only difference being a single thymine to cytosine transition in each sequence (a total of 107 identical bases). The pyrimidine oligonucleotides of each phage DNA show extensive internal sequence homology among each other with up to eight bases identical in sequence in pairs of different oligonucleotides. Another interesting observation is the occurrence of symmetrical sequences (true palindromes) which read the same forwards as backwards. The longest symmetrical sequence is the nonanucleotide C4T5 sequence, C-T-C-T-T-T-C-T-C, present in both S13 and phiX174 DNAs. The extensive sequence homology observed between the pyrimidine oligonucleotides of S13 and phiX174 supports the close relationship of the two phages and provides further evidence that they were derived from recent common ancestors.

Base Sequence↗
PubMed1972

Characterization of bacteriophage S13 suN15 single-strand and replicative-form deoxyribonucleic acid.

The deoxyribonucleic acid (DNA) of bacteriophage S13 was shown to be single-stranded by the criteria of reactivity with formaldehyde, dependence of optical density on ionic strength, broad temperature-absorbance profile, and lack of molar equivalence of the purine and pyrimidine bases. The DNA has a molecular weight of 1.8 x 10(6) daltons, an S degrees (20) of 24.6 in SSC (0.15 m NaCl plus 0.015 m sodium citrate), and a buoyant density of 1.726 g/cc in CsCl. Electron microscopy showed the molecule to be circular. S13 replicative-form DNA was shown to be a double-stranded, circular molecule with a molecular weight of 3.5 x 10(6) daltons, an S([ill]) of 20.7 in SSC, and a buoyant density in CsCl of 1.710 g/cc. The finding that S13 DNA is slightly more pyrimidine-rich than phiX174 DNA but is indistinguishable by all other parameters supports the close genetic relationship between the two bacteriophages.

Centrifugation, Density Gradient↗