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J F Chiu

Publications and source records attributed to J F Chiu.

At least 109 records · Page 6Linked to original sources
PubMed1980

Immunospecificity of nuclear antigens in chicken erythroid cells.

Specific antisera were produced against chicken reticulocyte dehistonized chromatin. The antisera reacts strongly with chicken reticulocyte chromatin, but only marginally with chicken erythrocyte chromatin. There is no reticulocyte antigen detected in chicken liver. Reticulocyte maturation is accompanied by a gradual decrease in the chromatin immunological activity and template capacity. The reduction of immunological activity is due to the change of chromatin conformation during erythrocyte maturation. Dehistonization and sonication of erythrocyte chromatin raises the erythrocyte chromatin immunological activity to levels similar to those of reticulocyte chromatin. The erythrocyte nuclear antigens are class specific, not being found in frog erythroid cell or murine Friend leukemia cell chromatins.

Animals↗
PubMed1980

Chicken reticulocyte nuclear antigen: its identification and relation to transcriptive activity in erythropoietic cells.

Antibodies to chicken reticulocyte dehistonized chromatin were produced. These antibodies can distinguish between chromatin from reticulocytes and erythrocytes and have no activity with chicken liver chromatin. The antibodies will also differentiate between reticulocytes and erythrocytes by the the horseradish peroxidase bridge localization technique. The nonhistone protein components of the antigenic complex are very tightly bound to the DNA, removable by extraction with sodium dodecyl sulfate but not 2.5 M NaCl-5 M urea. Our data indicate that the antigen complexes could actually be present in both reticulocytes and erythrocytes but that chromatin condensation causes a structural masking of the complexes which coincides with the known decline in transcriptive activity of the erythrocyte.

Animals↗
PubMed1980

Antigenic changes in nuclear chromatin in 1,2-dimethylhydrazine-induced colon carcinogenesis.

Chromosomal nonhistone protein-DNA complexes prepared from rat colon adenocarcinoma were used to produce tumor specific antisera in rabbits. The antisera reacted specifically in complement fixation tests with chromatins isolated from rat colon tumor and not with those from a number of other rodent tumors and normal tissues, including normal rat colon epithelial cells. Tumor specificity of this antisera was also demonstrated by their cross reactivity with human and mouse colon adenocarcinomas. Immunohistochemical localization of the antigens by the horseradish peroxidase bridge technique demonstrated their presence in the nuclei. The changes in the immunospecificity of the nuclear antigens in chromatin were studied in colon of rats treated with 1,2-dimethylhydrazine. A significant change in the immunospecificity of the chromatin occurred as early as the fourth week after 1,2-dimethylhydrazine treatment was begun.

Adenocarcinoma↗
PubMed1980

Colon tumor specific nuclear antigen with potential as a pre-tumor diagnostic probe.

Tumor specific nuclear antigen was demonstrated in early stages of chemically-induced colon carcinogenesis. At these early stages, there is no observable nuclear or cytoplasmic alteration in the colon mucosae. The rise in tumor specific nuclear antigen in carcinogen-treated animals can be abolished by simultaneous treatment with carcinogen inhibitor. The potential for tumor specific nuclear antigen to be used as a pretumor diagnostic probe is discussed.

Animals↗
PubMed1979

alpha 1-Fetoprotein mRNA of rat yolk sac and hepatoma.

Rat alpha 1-fetoprotein mRNA was isolated and purified to apparent homogeneity by means of immunoadsorption and oligo (dT) cellulose affinity chromatography. Purified AFP mRNA migrated as a 21S peak in 2.5% SDS-polyacrylamide gels. The translation product of this mRNA in micrococcal nuclease treated reticulocyte lysate was identified as AFP by specific immunoprecipitation, SDS-gel electrophoresis and tryptic digestion analysis. DNA complimentary to AFP mRNA was synthesized with avian meyloblastosis virus RNA-dependent DNA polymerase. This AFP cDNA was used as a probe to quantitate AFP mRNA in the developing rat liver and to compare the complexity and diversity of AFP mRNA derived from the normal rat liver and Morris hepatoma 7777. We found that the amount of functional AFP mRNA is decreasing during liver development. There is very little, if any, AFP mRNA in the adult rat liver. A high degree of homology between the AFP mRNA sequences of yolk sac and hepatoma was also found.

Animals↗
PubMed1979

Isolation of rat alpha1-fetoprotein messenger RNA from Morris hepatoma 7777.

A double-antibody procedure has been developed for the isolation of alpha1-fetoprotein (AFP)-synthesizing polysomes from Morris hepatoma 7777. The polyadenylic acid-containing RNA, subsequently purified by differential sedimentation on sucrose gradient and oligodeoxythymidylic acid-cellulose chromatography, migrates as a single 21S component in polyacrylamide gel electrophoresis; in a cell-free translation system, it yields a peptide product immunoprecipitable by anti-rat AFP antiserum, but not by anti-rat albumin, and which migrates slightly faster than serum AFP on sodium dodecyl sulfate-urea-polyacrylamide gels. This messenger RNA fraction was used for the synthesis of a radioactive complementary DNA. In hybridization assays, the complementary DNA reassociated with its purified template at a Cr0t1/2 [product of RNA concentration (mol of nucleotides per liter) X half-time (sec)] of 1.5 X 10(-2). By constitute 3,2, and less than 0.01% of total polyadenylic acid-containing polysomal RNA of Morris hepatoma 7777, 10-day-old-rat liver, and adult rat liver, respectively. The high specificity of the polysome immunoprecipitation system, the electrophoretic homogeneity of the isolated messenger RNA fraction, its selective translation into AFP, and the specificity of the hybridization probe indicate that the procedure described yields a highly purified rat AJP messenger RNA.

Animals↗
PubMed1979

Immunospecificity of nuclear nonhistone protein-DNA complexes in colon adenocarcinoma.

Tumor-specific antisera against dehistonized chromatin isolated from transplantable colon adenocarcinoma (from male noninbred Sprague-Dawley rats) were produced. The specificities of these antisera were determined by complement fixation. In the presence of these antisera, only chromatin from colon adenocarcinoma significantly fixed complement, whereas chromatins isolated from normal rat colon epithelia were inactive. Administration of 1,2-dimethylhydrazine to rats produced an early change in the immunospecificity of colon epithelial chromatin similar to that for colon adenocarcinoma. Several lines of experimental evidence indicated that nuclear antigen was not a carcinoembryonic antigen-like substance. Common antigens were also present in human colon adenocarcinomas.

Adenocarcinoma↗
PubMed1979

Specificity of DNA-associated nuclear antigens in HeLa cells and distribution during the cell cycle.

Chromosomal nonhistone protein:DNA complexes prepared from synchronized HeLa cells were used to immunize white rabbits. The antisera reacted specifically in complement fixation tests with chromatins isolated from HeLa cells and not with those from a number of other human and animal tissues. Specificity to this cell type was also demonstrated by immunocytochemical reaction. Both immunochemical tests revealed that the specific antigens are continuously present throughout the cell cycle. The immunological activity was dependent upon chromosomal nonhistone protein(s) being bound to DNA. Our findings are consistent with these chromatin antigens being stable nuclear components [complexes of chromosomal non-histone protein(s) with DNA] characteristic of cellular differentiation.

Antigens↗
PubMed1978

Immunological properties of fractionated avian erythroid nuclei.

Chicken reticulocyte (polychromatic primitive erythrocyte) and erythrocyte chromatin was fractionated by ultrasound shearing and salt precipitation into three fractions differing in their activities to support the in vitro RNA synthesis. The transcriptionally active fraction of chicken reticulocyte chromatin which represented only about 0.5% of the total nuclear DNA contained essentially all the chromatin-associated endogenous RNA. Approximately 2% of this endogenous reticulocyte RNA hybridized to globin cDNA probe and could be translated in vitro into polypeptides which coelectrophoresed with the in vitro translation product of isolated chicken globin mRNA or chicken globin marker. Each of the three fractions had a characteristic distribution of chromosomal proteins and endogenous RNA. Polyacrylamide gel electrophoresis of the chromosomal proteins showed differences in their distribution among individual fractions of the same cell type and among corresponding fractions of reticulocyte or erythrocyte chromatin. Antisera produced against dehistonized reticulocyte chromatin were specific for reticulocyte but not erythrocyte chromatin. When reacted with each of the differentially templating chromatin fractions, it was found that reticulocyte-specific antibodies were highly reactive with the template-active fraction of reticulocytes, but essentially nonreactive with any other reticulocyte fraction. This same antiserum was not significantly reactive toward any erythrocyte fraction. The antigenicity of the template-active fraction of reticulocytes was abolished after pronase or DNase II digestion, but only partially diminished after DNase I digestion.

Animals↗
PubMed1978

Human granulocyte specific nuclear antigen(s). I: Production of antisera and determination of specificity.

Non-histone protein-DNA complexes isolated from human lung tissue were used to immunize New Zealand rabbits. Quantitative microcomplement fixation and immunocytochemistry revealed a specific chromatin antigen(s) in the human granulocyte nucleus. The study demonstrates the feasibility of employing antisera against chromosomal non-histone protein-DNA complexes for the immunochemical identification of cell types.

Animals↗
PubMed1978

Purification of nuclear antigens in Novikoff hepatoma.

Nuclear antigen in Novikoff hepatoma chromatin was partially purified and characterized. As indicated by complement fixation assay, this antigen was present in chromatin of embryonic livers and several transplantable tumors. It was not detected in normal tissue chromatins of the same animals. For its immunological specificity this protein antigen (molecular weight 45,000-60,000) had to be complexed with DNA. Preliminary experiments indicate that specific nuclear protein antigens are also present in human tissues and spontaneous malignancies.

Animals↗