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G Cannon

Publications and source records attributed to G Cannon.

10 recordsLinked to original sources

Nucleic acid sequence analysis software for microcomputers.

It is clear that a computer-aided data control system is required for even small laboratories generating nucleic acid data. While the molecular biologist at many universities and large research institutions has access to mainframe computers and nucleic acid sequence analysis software, many find it more convenient to perform sequence analysis on microcomputers that are typically located within the investigator's laboratory and totally dedicated to sequence storage and analysis, in essence giving the investigator more personal control of analysis activities than is sometimes possible with shared mini- or mainframe computers. New programs are being written and released at an increasing rate to perform increasingly more complex and specialized analyses using small computer-based systems. This trend will undoubtedly continue, fueled by the need to manage the ever increasing quantity of sequence data.

Base Sequence

Induction of B-cell lymphomas in athymic NIH Swiss nu/nu mice.

A B-cell lymphoma was induced in athymic NIH Swiss nu/nu mice by challenging the animals with NIH3T3 cells, previously transfected with a recombinant DNA carrying a human oncogene hhcM, ligated to an SV40 promoter with a neomycin-resistance marker. The gross pathology of the tumor-bearing animal revealed generalized lymphadenopathy and the histopathology indicated widespread infiltration of lymphocytes into organs, such as brain, liver, kidney and lung, in addition to the lymphoid tissues and spleen; the appearance was consistent with diffuse histiocytic lymphoma. Direct immunofluorescence assays with specific typing anti-sera on live cells prepared from spleen and various lymph nodes in short-term culture, suggested the cells were B-cells. This B-cell lymphoma provides an experimental model, not only for studying possible oncogene activation but also for studying the various interactions involved in signal transduction essential for the activation of B-cell proliferation and differentiation.

Animals

The sugar lobby.

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Carbohydrates

Chloroplast DNA synthesis during the cell cycle in cultured cells of Nicotiana tabacum: inhibition by nalidixic acid and hydroxyurea.

The effects of nalidixic acid and hydroxyurea on nuclear and chloroplast DNA formation in cultured cells of Nicotiana tabacum were investigated. At low concentrations (5 and 20 micrograms/ml) nalidixic acid, an inhibitor of DNA gyrase, exhibited a greater inhibitory effect on plastid DNA synthesis than on nuclear DNA formation. Since the plastid genome is a circular double-stranded DNA, this is consistent with the proven involvement of a DNA gyrase in the replication of closed circular duplex DNA genomes in procaryotic cells. At a high concentration of nalidixic acid (50 micrograms/ml), DNA synthesis in both the plastid and nuclear compartment was rapidly inhibited. Removal of the drug from the culture medium led to the resumption of DNA synthesis in 8 h. Hydroxyurea, an inhibitor of ribonucleoside diphosphate reductase, also depresses nuclear as well as plastid DNA formation. Removal of hydroxyurea from the blocked cells leads to a burst of nuclear DNA synthesis, suggesting that the cells had been synchronized at the G1/S boundary. The recovery of plastid DNA synthesis occurs within the same time frame as that of nuclear DNA. However, whereas plastid DNA formation is then maintained at a constant rate, nuclear DNA synthesis reaches a peak and subsequently declines. These results indicate that the synthesis of plastid DNA is independent of the cell cycle events governing nuclear DNA formation in cultured plant cells.

Cell Cycle

Deoxyribonucleic acid in Nitrobacter carboxysomes.

Carboxysomes were isolated from Nitrobacter winogradskyi and Nitrobacter agilis. The icosahedral particles contained double-stranded deoxyribonucleic acid (DNA). In the presence of ethidium bromide and cesium chloride, the particle-bound DNA had a buoyant density of rho 25 = 1.701 g/cm3. Electron microscopy revealed the DNA to be a 14-micron circular molecule.

Centrifugation, Density Gradient

Delayed hypersensitivity reactions of cancer patients to antigens on lymphoid cell lines.

Four-hundred and fifty nine cancer patients were skin tested with extracts from five lymphoid cell lines. More than 50% of patients with lymphoma had positive skin tests with the extracts prepared from the cell line derived from Burkitt's lymphoma (BL) and more than 50% of nasopharyngeal carcinoma (NPC) patients reacted to the NPC-derived cell line extracts. Although the significant association between patient diagnosis and orgin of cell lines suggested that tumor-associated antigens were responsible for the pattern of delayed hypersensitivity, problems in standardization of antigen potency and non-specificity need to be resolved before this in vivo assay achieves its full potential.

Antigens, Neoplasm

Location by immunoelectron microscopy of carcinoembryonic antigen on cultured adenocarcinoma cells.

The tissue-culture cell line HT-29, derived from a primary colon adenocarcinoma and previously shown to secrete carcinoembryonic antigen (CEA), was examined by immunoelectron microscopy for the location of CEA in relation to the cells. CEA was closely adjacent to the plasma membrane, a location indistinguishable from that of alloantigens and other tumor-associated antigens.

Adenocarcinoma