Benzo(a)pyrene induces nuclear-DNA adducts in plant cell suspension culture. Detection by [32P] postlabelling.
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Autoradiography↗
Biomedical subjects
G Keith
Publications and source records attributed to G Keith.
Heterogeneities in vertebrate tRNAs(Trp) avian retroviruses package only as a primer the tRNA(Trp) lacking modified m2G in position 7.
Bovine, rabbit and chicken tRNA(Trp) species and tRNA(Trp) packaged in avian myeloblastosis virus were separated and purified using two-dimensional gel electrophoresis and their primary structures were determined. Two major tRNA(Trp) species (1 and 2) were identified in beef and rabbit, two minor ones (3 and 4) in beef and only one minor in rabbit. Their structures differ by 4 nucleotide substitutions located in the D, S and T loops (positions 16, 47, 57 and 59). Species 3 and 4 differ from one another by only one nucleotide at position 2. Differences between tRNA(Trp) species were also observed in the extent of methylation of some nucleotides. Chicken tRNA(Trp) presents only one species similar to the mammalian type 1 tRNA(Trp). In the case of the three studies animals this tRNA could be separated into two subspecies, which differ by a post-transcriptional modification of nucleotide 7 in the acceptor stem: G or m2G. However only the nonmethylated species is used as the primer of DNA-RNA directed retrotranscription since it is only that form which was found in avian retroviruses. The methylation of G to m2G at position 7 could thus prevent the recognition of tRNA(Trp) by retroviral protein(s) responsible for the selective packaging of the primer tRNA(Trp).
Animals↗
The primary structure of six leucine isoacceptor tRNAs of yellow lupin seeds. The structural requirements for amber tRNA suppressor activity.
Six tRNA(Leu) isoacceptors from yellow lupin seeds were purified, sequenced, and their readthrough properties over the UAG stop codon were tested using TMV RNA as a messenger. The tested tRNAs(Leu) did not show amber suppressor activity. The partial structure of tRNA(Gln), a minor species in yellow lupin, was also determined. Comparison of the nucleotide sequence of all known isoacceptors of tRNA(Tyr), tRNA(Gln) and tRNA(Leu) from plants, mammals and ciliates enabled us to find general structural requirements for tRNA to be a UAG suppressor. From the partial sequence of lupin tRNA(Gln) we suggest that it will have readthrough properties.
Autoradiography↗
Use of two-dimensional thin-layer chromatography for the components study of poly(adenosine diphosphate ribose).
Two-dimensional thin-layer chromatography on cellulose plates has been used for separating and quantifying the three adenosine derivatives: AMP, phosphoribosyl AMP (PRAMP), and (PR)2AMP obtained by venom phosphodiesterase digestion of poly(ADP-ribose). In vitro synthesized polymer, up to 300 derivatives in length were studied. Some parameters of the complexity of poly(ADP-ribose) could be deduced from our results: (i) The first branching point appears in fragments of approximately 21 derivatives in length. (ii) The branching points are located at regular distances of approximately 41 derivatives from each other.
Adenosine Monophosphate↗
Plasma glucose and insulin levels during the menstrual cycles of normal women and premenstrual syndrome patients.
Three-hour oral glucose tolerance tests were performed on days 5 and 25 of ovulatory menstrual cycles in 26 women. The women were divided into normal (n = 9) and premenstrual syndrome (PMS) (n = 17) categories. Ovulation was confirmed by basal body temperature records and plasma progesterone levels. There were no statistically significant changes in the plasma glucose or insulin levels between the two tests in either group. Except for a higher two-hour plasma insulin concentration on the day 5 test in normal women, no statistically significant carbohydrate differences were noted between the groups. The data suggest that alterations in carbohydrate metabolism are not important in PMS.
Blood Glucose↗
Clostridium difficile toxin B: characterization and sequence of three peptides.
The cytotoxin, also named toxin B, was isolated from a toxigenic strain of Clostridium difficile, purified to homogeneity and partially characterized. The purification procedure included ultrafiltration followed by anion-exchange chromatography. We noticed that a non-specific nucleic material eluted with the protein during the purification. The presence of these nucleic acids appeared to be important for the toxic activity of the protein. Some characteristics of the cytotoxin were examined, especially the amino acid composition and the sequence of three tryptic fragments.
Amino Acid Sequence↗
Presence of phosphorylated O-ribosyl-adenosine in T-psi-stem of yeast methionine initiator tRNA.
We report in this paper on isolation and characterization of two unknown nucleosides G* and [A*] located in the T-psi-stem of yeast methionine initiator tRNA, using the combined means of HPLC protocols, real time UV-absorption spectrum, and post-run mass spectrometry by electron impact or fast atom bombardment. The G* nucleoside in position 65 was identified as unmodified guanosine. The structure of the unknown [A*] in position 64 was characterized as an isomeric form of O-ribosyl-adenosine by comparison of its chromatographic, UV-spectral and mass spectrometric properties with those of authentic O-alpha-ribofuranosyl-(1"----2')-adenosine isolated from biosynthetic poly(adenosine diphosphate ribose). Our studies also brought evidence for the presence of a phosphorylmonoester group located on this new modified nucleoside [A*], when isolated by ion exchange chromatography from enzymic hydrolysis of yeast initiator tRNAMet without phosphatase treatment.
Adenosine↗
HIV-1 reverse transcriptase specifically interacts with the anticodon domain of its cognate primer tRNA.
The virion cores of the replication competent type 1 human immunodeficiency virus (HIV-1), a retrovirus, contain and RNA genome associated with nucleocapsid (NC) and reverse transcriptase (RT p66/p51) molecules. In vitro reconstructions of these complexes with purified components show that NC is required for efficient annealing of the primer tRNALys,3. In the absence of NC, HIV-1 RT is unable to retrotranscribe the viral RNA template from the tRNA primer. We demonstrate that the HIV-1 RT p66/p51 specifically binds to its cognate primer tRNALys,3 even in the presence of a 100-fold molar excess of other tRNAs. Cross-linking analysis of this interaction locates the contact site to a region within the heavily modified anti-codon domain of tRNALys,3.
Anticodon↗
Linkage heterogeneity between X-linked retinitis pigmentosa and a map of 10 RFLP loci.
In nine families in which X-linked retinitis pigmentosa (XLRP) is segregating, the lod scores of XLRP in a map of 10 RFLP loci were obtained by multipoint linkage analysis. The XLRP locus was located telomeric to DXS7 in seven of the families and centromeric to DXS7 in two of the families. Under the hypothesis of two XLRP loci, a heterogeneity (admixture) test was performed, providing significant evidence of heterogeneity in XLRP (P less than .01). No correlation was detected between the clinical manifestations of XLRP and the two different disease loci.
Chromosome Mapping↗
Relative content of isoaccepting tRNAs for glycine and proline in avian tendon cells with different rates of procollagen synthesis.
The relative amounts of iso-tRNAsGly and iso-tRNAsPro existing in chick embryo tendon are indicative of a specialization of the tRNA population for collagen synthesis. These amounts are not modified (i) in primary avian tendon (PAT) cells in culture for which the procollagen production varies from about 10% of total protein synthesis to 60% and (ii) in tendons from immature chicks, which show a 3-fold decrease of procollagen production with increasing age. The characteristic tRNA pattern was not maintained in cells which had lost the ability to make high levels of collagen as observed in the cases of: (i) PAT cells reaching confluency; (ii) virus-transformed PAT cells and (iii) tendon from adult chick. Our data are consistent with the idea that tendon tRNA specialization for collagen synthesis is a differentiation feature independent of the expression level of the collagenic function but related to its maintenance.
Aging↗
The nucleotide sequence of tRNA(Ser) and tRNA(Ile) of yellow lupin seeds.
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Base Sequence↗
Distribution of isoaccepting tRNAs and codons for proline and glycine in collagenous and noncollagenous chicken tissues.
The relation between codon usage and tRNA content for proline and glycine, the major constituents of collagen, was studied in two tissues: the magnum of laying hen oviduct and the leg tendons of chick embryo where collagen is produced. Although the relative contents of tRNA(GCCGly) and tRNA(IGGPro) in tendons, as compared to magnum indicate a specialization of the tRNA population for collagen synthesis, the distribution of the preponderant codons in collagen mRNA is correlated but at a lesser extent to that of their cognate tRNAs.
Animals↗
Small finger protein of avian and murine retroviruses has nucleic acid annealing activity and positions the replication primer tRNA onto genomic RNA.
Retrovirus virions carry a diploid genome associated with a large number of small viral finger protein molecules which are required for encapsidation. Our present results show that finger protein p12 of Rous sarcoma virus (RSV) and p10 of murine leukaemia virus (MuLV) positions replication primer tRNA on the replication initiation site (PBS) at the 5' end of the RNA genome. An RSV mutant with a Val-Pro insertion in the finger motif of p12 is able to partially encapsidate genomic RNA but is not infectious because mutated p12 is incapable of positioning the replication primer, tRNATrp. Since all known replication competent retroviruses, and the plant virus CaMV, code for finger proteins analogous to RSV p12 or MuLV p10, the initial stage of reverse transcription in avian, mammalian and human retroviruses and in CaMV is probably controlled in an analogous way.
Avian Sarcoma Viruses↗
Completion of the rabies virus genome sequence determination: highly conserved domains among the L (polymerase) proteins of unsegmented negative-strand RNA viruses.
We have now completed the rabies genome structure by the cloning and the sequencing of the entire L gene and the 5' untranscribed region. The L gene encodes a single open reading frame 2142 amino acids in length (244,206 Da) that corresponds to the viral RNA-dependent RNA polymerase. In contrast with other isofunctional proteins, the rabies polymerase exhibits a high degree of homology with the vesicular stomatitis virus polymerase, and a lesser degree, although significant, with those of Sendai virus and Newcastle disease virus, which suggests a differential evolution of the different cistrons. We have observed several strongly conserved stretches which may designate the independent functional domains of this multifunctional protein. In addition to the conservation of related transcription signals (N. Tordo et al. (1986) Proc. Natl. Acad. Sci. USA 83, 3914-3918.), this highlights the striking selective pressure on elements involved in transcription and replication mechanisms, and provides further evidence for a common ancestry of Rhabdoviridae and Paramyxoviridae families. The terminal complementarity observed in the rabies genome suggests the conservation of important genomic signals.
Amino Acid Sequence↗
Sequence of the 3386 3' nucleotides of the genome of the AVO1 strain rabies virus: structural similarities in the protein regions involved in transcription.
DNA fragments complementary to the genome of an avirulent strain (AVO1) of the rabies virus were cloned and sequenced. The sequence of the 3386 nucleotides from the 3' end covers the genes encoding the leader RNA, the nucleoprotein N, the phosphoprotein M1 and the matrix protein M2, as well as the intergenic regions. Comparison of the AVO1 sequence with those of other rabies strains reveals a very high conservation at both the nucleotide and the amino acid levels. The non-protein coding regions of the genome (leader gene, untranslated regions flanking mRNAs, untranscribed intergenic regions) are discussed in terms of their possible involvement in the rabies virus biology. Comparison of the rabies genome with those of other unsegmented negative strand RNA viruses (rhabdoviruses and paramyxoviruses) indicates that the start and stop transcription signals, located at the border of each gene encoding a protein, and the regions of the phosphoprotein and matrix proteins that could be implicated in the transcription process, retain a similar overall structure. Thus, it appears that during evolution, these virus genomes have diverged while keeping the protein structures and regulatory sequence important in transcription. These results prompt us to propose that the major distinctive feature of the rabies transcription may arise from the highly variable intergenic regions where the attenuation of transcription is assumed to take place.
Base Sequence↗
Evidence for the existence of an expressed minor variant tRNAPhe in yeast.
Two expressed brewer's yeast tRNAsPhe, a major and a minor one, have been purified and sequenced. The major tRNAPhe corresponds to the already known tRNAPhe, whereas the minor one differs from the former in the substitution of T6-A67 by C6-G67 base pair in the "acceptor stem". The minor tRNAPhe contaminates all preparations of yeast tRNAPhe except those prepared by polyacrylamide gel electrophoresis.
Base Sequence↗
[100 years later...the rabies virus].
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Genes, Viral↗
Accumulation and specific cleavage of 5S RNA in the isthmus of laying hen oviduct. Evidence for three chicken 5S RNA.
RNA extracts from the isthmus of laying hen oviduct contain truncated 5S RNA molecules that were found to be shorter at their 5' terminus as compared to native 5S RNA I and II. Moreover one of the truncated species differs from 5S RNA I by the absence of the 3' end nucleotide. The truncated forms increase of about 70% the total 5S RNA (intact + truncated) in the isthmus, as compared to the other studied tissues. Furthermore 5S RNA I is heterogeneous: 25% have A instead of U at the 3' end, and some evidence was obtained for the existence of two 5S RNA I conformers.
Animals↗