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B Cordell

Publications and source records attributed to B Cordell.

88 records · Page 5Linked to original sources
PubMed1979

tRNATrp as primer for RNA-directed DNA polymerase: structural determinants of function.

The specific interactions between the RNA-directed DNA polymerase of avian oncornavirus and the tRNATrp primer required for initiation of viral DNA synthesis in vitro were examined. Two distinct interactions, stable binding of the tRNATrp to the enzyme and initiation of viral DNA synthesis by the enzyme with tRNATrp as primer, were characterized as to the structure of tRNATrp required. Different structural features of the tRNATrp were shown to be necessary for each type of interaction. The entire primary structure and native conformation of tRNATrp are both required for binding to reverse transcriptase. Fragments of tRNATrp and intact tRNATrp in an altered conformation cannot be bound by the enzyme using an assay which detects high affinity binding between reverse transcriptase and native tRNATrp. In contrast, fragments of the tRNATrp molecule can serve as primers for viral DNA synthesis with normal efficiency as compared to intact tRNATrp. The fragments which initiate transcription must contain a minimum specific nucleotide sequence which extends from the 3' terminus of the tRNATrp through 27 residues of the molecule. This portion of the tRNATrp may be a major structural determinant of specificity in initiation.

Alpharetrovirus↗
PubMed1979

Isolation and characterization of a cloned rat insulin gene.

The two nonallelic genes, insulin I and II of the rat, are separated by at least 7 kb of DNA. There is no obvious similarity in the sequence organization surrounding each gene, although the coding regions of the genes themselves share extensive homology. In three strains of rat, the insulin II gene lies predominantly on a 4.0 kb Eco RI restriction fragment, whereas the insulin I gene is located on a 9.4 kb Eco RI fragment in the Hooded strain, on a 7.2 kb Eco RI fragment in the Osborne-Mendel strain, and on both a 9.4 and a 7.2 kb Eco RI fragment in Sprague-Dawley rats. The 9.4 kb Eco RI fragment from Hooded rat DNA was isolated using the lambda cloning system, and the nucleotide sequence of this isolated rat insulin I gene and adjacent regions was determined. A translation in one frame of the sequence of the cloned gene confirms the protein sequence determined for rat pre-proinsulin I. The coding region of this gene lacks intervening sequences, although a presumptive intervening sequence of 119 bp is located in the 5 untranslated region preceding the prehormone sequence. The junctions around the 119 bp segment are identical to those which flank intervening sequences of other eucaryotic genes, AGGT. The site of polyadenylation was determined by direct sequence comparison with rat insulin cDNA clones, and a potential 5 "capping" site is proposed. A DNA sequence preceding this 5 "capping" site in the rat insulin I gene, TATAAAGC, is homologous to corresponding regions in other eucaryotic genes that have been proposed as putative promoter sites for the initiation of transcription.

Animals↗
PubMed1979

Gene localization by chromosome fractionation: globin genes are on at least two chromosomes and three estrogen-inducible genes are on three chromosomes.

Chicken metaphase chromosomes were partially purified by rate zonal centrifugation, and DNA was prepared from each of the fractions of the sucrose gradient. The DNA was digested with various restriction enzymes and subjected to electrophoresis in agarose gels. The DNA was transferred to nitrocellulose filters (as described by Southern), and the filters were hybridized with cDNA probes. Four globin genes alpha A, alpha D, beta, and rho or epsilon are located on at least two chromosomes, and three of the estrogen-inducible genes of the hen oviduct--ovalbumin, ovomucoid, and transferrin--are on three different chromosomes. These experiments also confirm our earlier assignment of the endogenous viral sequence related to Rous-associated virus-0 to a separate (and larger) chromosome than the cellular sequence related to the transforming gene of avian sarcoma virus (cellular sarc), although it now appears that cellular sarc is on a small macrochromosome, rather than on a microchromosome.

Animals↗
PubMed1978

Structure and processing of yeast precursor tRNAs containing intervening sequences.

We have isolated a precursor of yeast tRNATyr and shown that it contains an intervening sequence identical to that found in the gene for tRNATyr. The conformation of pre-tRNATyr is similar to that of mature tRNATyr except for the anticodon loop. The loop is sensitive to endonucleolytic cleavage by S1 nuclease near to the ends of the intervening sequence. This pre-tRNA is functionally inactive as it cannot be aminoacylated and the anticodon is not accessible for hydrogen bonding. A crude nuclear extract from yeast contains an excision-ligase activity which will process pre-tRNATyr into mature tRNATyr.

Anticodon↗
PubMed1978

At least 104 nucleotides are transposed from the 5' terminus of the avian sarcoma virus genome to the 5' termini of smaller viral mRNAs.

Cells producing avian sarcoma virus (ASV) contain at least three virus-specific mRNAs, two of which are encoded within the 3' half of the viral genome. Each of these viral RNAs can hybridize with single-stranded DNA(cDNA5') that is complementary to a sequence of 101 nucleotides found at the 5' terminus of the ASV genome, but not within the 3' half of the genome. We proposed previously (Weiss, Varmus and Bishop, 1977) that this nucleotide sequence may be transposed to the 5' termini of viral mRNAs during the genesis of these RNAs. We now substantiate this proposal by reporting the isolation and chemical characterization of the nucleotide sequences complementary to cDNA5' in the genome and mRNAs of the Prague B strain of ASV. We isolated the three identified classes of ASVmRNA (38, 28 and 21S) by molecular hybridization; each class of RNA contained a "capped" oligonucleotide identical to that found at the 5' terminus of the ASV genome. When hybridized with cDNA5', each class of RNA gave rise to RNAase-resistant duplex hybrids that probably encompassed the full extent of cDNA5'. The molar yields of duplex conformed approximately to the number of virus-specific RNA molecules in the initial samples; hence most if not all of the molecules of virus-specific RNA could give rise to the duplexes. The duplexes prepared from the various RNAs all contained the capped oligonucleotide found at the 5' terminus of the viral genome and had identical "fingerprints" when analyzed by two-dimensional fractionation following hydrolysis with RNAase T1. In contrast, RNA representing the 3' half of the ASV genome did not form hybrids with cDNA5'. We conclude that a sequence of more than 100 nucleotides is transposed from the 5' end of the ASV genome to the 5' termini of smaller viral RNAs during the genesis of these RNAs. Transposition of nucleotide sequences during the production of mRNA has now been described for three families of animal viruses and may be a common feature of mRNA biogenesis in eucaryotic cells. The mechanism of transposition, however, and the function of the transposed sequences are not known.

Avian Sarcoma Viruses↗
PubMed1977

Inhibition of amino acyl tRNA synthetase activity by copper complexes of two metal binding ligands. N-Methyl isatin beta-thiosemicarbazone and 8-hydroxyquinoline.

Copper complexes of N-methyl isatin beta-thiosemicarbazone, 1-formyl isoquinoline thiosemicarbazone and thiosemicarbazide inhibit amino acyl tRNA synthetase activity. Copper complexes of 8-hydroxyquinoline and 8-mercaptoquinoline also inhibit. The 1 : 1 ligand-metal complex is significantly more active than the 2 : 1 complex. The free ligand alone and copper sulfate alone have little, if any, effect. These complexes have no effect on the ATP-PPi exchange reaction and do not cause deacylation of amino acyl tRNAs. This indicates that the process inhibited by these complexes is the amino acylation reaction. This is the first report that these copper binding ligands can inhibit enzymatic processes which involve nucleic acids but which are not viral, bacterial or mammalian cell polymerases.

Amino Acyl-tRNA Synthetases↗
PubMed1976

Nucleotide sequence that binds primer for DNA synthesis to the avian sarcoma virus genome.

Initiation of transcription from the genome of avian sarcoma virus by RNA-directed DNA polymerase in vitro requires tRNAtrp as a primer. The tRNA is bound to the viral genome by a sequence of 16 contiguous nucleotides (U-C-A-C-G-U-C-G-G-G-G-U-C-A-C-Cp), beginning with the penultimate base at the 3' terminus of the primer and extending through the acceptor stem into loop IV of the tRNA. Consequently, the native conformation of the tRNA must be disrupted by the binding of primer to the viral genome. The binding sequence does not include two adjacent residues of pseudouridine in loop IV, which distinguish the primer from many other tRNAs, and the 3' terminal adenosine of primer may also be excluded from base pairing with the viral genome.

Avian Sarcoma Viruses↗
PubMed1971

Viruses as an aid to cancer therapy: regression of solid and ascites tumors in rodents after treatment with bovine enterovirus.

Treatment of ascites and solid tumors in mice (Sarcoma-1 and Ehrlich ascites carcinoma) with bovine enterovirus-1 resulted in regression of the tumors without any pathological effect on the animals. Death of mice with lymphatic-leukemia L4946 was delayed after such treatment. The oncolytic specificity of the virus does not appear to involve the production of interferon, but requires specific adsorption of virus to the tumor cells. The specificity of killing extends to cells in culture, since viral-transformed cells and oncogenic cells are susceptible to the virus, in contrast to cells of untransformed lines and cells of primary cultures, which are resistant. The possibility of utilizing the specificity of nonvirulent viruses in therapeutic treatment of human cancers is considered.

Animals↗
PubMedDate not supplied

Additional arrows for the beta-amyloid target.

Currently, numerous postulates exist to explain the mechanism of beta-amyloid genesis. Fortunately, many molecular tools also exist to conduct the experiments which will identify the correct mechanism. In the process, therapeutic targets for Alzheimer's disease will be revealed.

Alzheimer Disease↗
PubMedDate not supplied

Neuronal DNA damage correlates with overexpression of interleukin-1beta converting enzyme in APPV717F mice.

Transgenic APPV717F mice, homozygous for a human minigene encoding the V717F familial Alzheimer's disease mutation, develop Abeta plaques similar to those seen in Alzheimer patients and show evidence of neuronal cell drop out in CA2-3 regions of the hippocampus at 8 months of age and older. Interleukin-1 (IL-1)beta (IL-1beta) converting enzyme (ICE) is a cysteine protease (caspase-1) that processes inactive (33 kDa) pro-IL-1beta to the active (17 kDa) inflammatory cytokine. We used immunohistochemistry, RT-PCR, and DNA cleavage (TUNEL) analysis to show progressive, age-associated increases in ICE mRNA levels, in the numbers of ICE-immunoreactive glia, and in the numbers of neurons showing evidence of DNA damage in APPV717F mice that commenced months prior to the appearance of Abeta plaques. Moreover, there were significant correlations between these parameters over an age range of 1-17 months. These findings are consistent with the idea that increases in ICE activity and expression contribute to neuronal injury in Alzheimer's disease.

Alzheimer Disease↗
PubMedDate not supplied

Isolation and characterization of the human pulmonary surfactant apoprotein gene.

Pulmonary surfactant is a phospholipid-protein complex which serves to lower the surface tension at the air-liquid interface in the alveoli of the mammalian lung and is essential for normal respiration. Inadequate levels of surfactant at birth, a frequent situation in premature infants, results in respiratory failure. In all species examined, surfactant is composed primarily of dipalmitoylphosphatidylcholine and two major protein species of relative molecular mass (Mr) 32,000 (32K) and 10K (refs 2-5). Reconstitution in vitro of purified 32K pulmonary surfactant apoprotein (PSAP) with synthetic lipids forms a lipoprotein complex that lowers surface tension by spreading to create a thin interfacial film. Here we describe the cloning of the human PSAP gene and complementary DNA, and discuss features of the unusual encoded protein.

Amino Acid Sequence↗
PubMedDate not supplied

Transgenic mice and modeling Alzheimer's disease.

The etiology of Alzheimer's disease (AD) is poorly understood, and no effective therapies are available. Although histopathology of the disease has been studied thoroughly, the relationship of various AD lesions to pathological processes and to dementia are debated. Progress would be greatly enhanced by existence of manipulable small animal models of the disease. Recently, transgenic strategies to developing such a model have been extensively explored. The approach has proved to be difficult and has yielded some disappointments, but also some encouraging results. Transgenic strategies for obtaining a model for AD are surveyed in this review and, as an illustration, early AD-like features of transgenic mice produced in our laboratory are described.

Alzheimer Disease↗
PubMedDate not supplied

Cultural diversity and patient teaching.

Cultural diversity challenges health care providers to facilitate bridging cross-cultural gaps with clients. It is through providing culturally relevant care that health care practitioners truly serve the needs of all clients in our diverse society. A theory of Cultural Care Diversity and Universality offers a framework for building linkages of clinical knowledge to cultural care. A four-step approach to providing culturally sensitive patient teaching is described: (1) health care providers should assess their own cultural beliefs and be aware of general ethnic, regional, and religious beliefs and practices in their area; (2) develop a teaching plan; (3) implement the plan; (4) evaluate the success of the teaching-learning process and make alterations based on evaluation. When providers assess clients' beliefs and practices and incorporate them into the teaching plan design, teaching becomes more relevant and clients become more successful at learning.

Cultural Characteristics↗