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T D Edlind

Publications and source records attributed to T D Edlind.

48 records · Page 3Linked to original sources
PubMed1985

Detection of Plasmodium falciparum using a synthetic DNA probe.

A labeled synthetic polynucleotide representing a repetitive sequence from Plasmodium falciparum was hybridized with genomic DNA spotted on nitrocellulose. After an overnight exposure, 0.1 ng of P. falciparum DNA was specifically detected and 0.01 ng was detected after an exposure of 1 week. The synthetic probe showed no cross-hybridization with host DNA or with DNA isolated from other species in the phylum Apicomplexa, P. vivax and Babesia species. Since synthetic DNA is easily prepared, the observed sensitivity and specificity suggests that synthetic DNA probes would be generally useful in diagnosis.

Animals↗
PubMed1984

Long range base-pairing in the leftward transcription unit of bacteriophage lambda. Characterization by electron microscopy and computer-aided sequence analysis.

Restriction fragments of bacteriophage lambda DNA corresponding to the major leftward transcription unit were purified, denatured to form single-stranded DNA, self-annealed, and examined by electron microscopy. Three intrastrand stem and loop secondary structures were observed reproducibly and the locations of the paired regions were determined. A method for computer-aided sequence analysis of these regions is presented and used to identify sets of base-pairings likely to account for the observed structures. One loop observed within gene Ea47 is postulated to involve pairing of sequences which include the polypeptide initiation and termination codons. Another loop is postulated to involve pairing of sequences in gene int with sequences located in the gam-cIII region. A third loop appears to involve sequences in and to the right of gene Ea22 paired with sequences located in the bet-gam region. A general discussion of base-pairing which gives rise to long range interactions is presented along with possible effects of the postulated models on gene expression.

Bacteriophage lambda↗
PubMed1983

Comparison of three methods for measuring locations of long range base pairing in single-stranded DNA by electron microscopy.

A comparison was made of three procedures used for measuring the locations of long range base pairing in single-stranded DNA. All three procedures gave equivalent results for the location of a transposon, Tn903, and for a loop created by pairing between the nut and operator segments on an EcoRI restriction fragment of lambda DNA. DNA molecules prepared by a T4 gene 32 protein procedure had the best contrast. The highest frequency of measurable loops resulted from a procedure which utilized ammonium acetate/formamide spreading conditions. This procedure also appeared to be the simplest and most satisfactory procedure. Only one procedure revealed the fact that the nutR and oR regions are separated by several hundred bases, but this procedure, which involves crosslinking with trioxsalen, gave generally unsatisfactory DNA morphology. None of the procedures revealed the existence of a short "bulge" loop of single-stranded DNA located between nutL and oL and a longer "bulge" loop located between nutR and oR.

Acetates↗
PubMed1980

Electron microscopic mapping of secondary structures in bacterial 16S and 23S ribosomal ribonucleic acid and 30S precursor ribosomal ribonucleic acid.

Electron microscopy revealed reproducible secondary structure patterns within partially denatured 16S and 23S ribosomal ribonucleic acid (rRNA) from Escherichia coli. When prepared with 50% formamide-100 mM ammonium acetate, 16S rRNA included two small hairpins that appeared in over 50% of all molecules. Three open loops were observed with frequencies of less than 25%. In contrast, 23S rRNA included a terminal open loop and two additional large structures in over 75% of all molecules. These secondary structure patterns were conserved in the 16S and 23S rRNA from Pseudomonas aeruginosa. The secondary structure of the 30S precursor rRNA from the ribonclease III-deficient E. coli mutant AB105 was mapped after partial denaturation in 70% formamide-100 mM ammonium acetate. Two large open loops were superimposed on the 16S and 23S rRNA secondary structure patterns. These loops were the most frequent structures found on the precursor, and their stems coincided with ribonuclease III cleavage sites. A tentative 5'-3 orientation was determined for the secondary structure patterns of 16S and 23S rRNA from their relative locations within 30S precursor rRNA. The relation of secondary structure to ribosomal protein binding and ribonuclease III cleavage is discussed.

Escherichia coli↗
PubMed1977

Secondary structure of RNA from bacteriophages f2 Qbeta, and PP7.

Electron microscopy of RNA-protein monolayers prepared under partial denaturing conditions has been used to compare the secondary structure of coliphage f2 and Qbeta and Pseudomonas aeruginosa phage PP7 RNAs. The secondary structure map of f2 RNA contains a central open loop and four symmetrically placed hairpins, which is similar to the pattern reported by Jacobson (A. B. Jacobson, Proc. Natl. Acad. Sci. U.S.A. 73:307-311, 1976) for the closely related phage MS2. With the same denaturing conditions, Qbeta RNA, which is 20% larger than f2 or PP7 RNA, has a central open loop and a smaller terminal loop. PP7 RNA has two large, closed secondary structures, one of which is nearly central. The base composition of PP7 RNA was determined and is similar to that of the group I coliphage RNAs. Thus, the greater amount of large base-paired structure is not related to an increased guanine-plus-cytosine content of PP7 RNA. With increased denaturing conditions, the central, closed structure of PP7 RNA is converted into an open loop. The central structures of all three phages include about 700 nucleotides. The relevance of these findings to the genetic maps of the coliphage RNAs is discussed.

Bacteriophages↗
PubMedDate not supplied

Entamoeba histolytica encodes a highly divergent beta-tubulin.

The microtubules of the amitochondrial parasite Entamoeba histolytica are atypical in certain respects. Consistent with this, we report that E. histolytica encodes the most divergent beta-tubulin identified to date, with only 54% to 58% identity to beta-tubulins from various species. A similarly divergent beta-tubulin is encoded by the related Entamoeba invadens; single gene copies appear to be present in both organisms. The Entamoeba sequences were compared with a database of 101 beta-tubulins, including the highly divergent sequence from another amitochondrial protozoan, Trichomonas vaginalis. A total of 81 residues were universally conserved, and 76 residues varied only once. Correlations with previous studies indicate that microtubule function is altered when most, but not all, conserved residues are mutated.

Amino Acid Sequence↗
PubMedDate not supplied

Characterization of the beta-tubulin gene of Pneumocystis carinii.

To examine the potential of antimicrotubule drugs for treating Pneumocystis carinii infections, and to learn more about this unusual organism on a molecular level, we are studying its tubulin genes. A 0.3 kbp fragment of the P. carinii beta-tubulin gene was amplified by the polymerase chain reaction. Sequence analysis of this DNA revealed that P. carinii beta-tubulin is most closely related to those of the fungal molds. Consistent with these results, P. carinii growth in vitro was sensitive to the antifungal benzimidazoles benomyl and carbendazim.

Albendazole↗