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Biomedical subjects

A C Cato

Publications and source records attributed to A C Cato.

81 records · Page 5Linked to original sources
PubMed1981

The pattern of protein synthesis induced by heat shock of HeLa cells.

While incubation of HeLa cells for 5--10 min at 45 degrees C does not affect subsequent cellular growth and DNA synthesis at 37 degrees C, there is an increased synthesis of specific proteins in the molecular weight region of 100 000, 72 000--74 000 and 37 000. The synthesis of these proteins reaches a maximum 2 h after the heat shock and while the protein themselves are stable, their synthesis declines to normal levels 4 h afterwards. The increased synthesis is blocked by actinomycin D but the addition of cycloheximide or NaF during the "induction' period is without effect.

Cycloheximide↗
PubMed1980

Recombinant plasmids containing avian vitellogenin structural gene sequences derived from complementary DNA.

Purified mRNA coding for chicken vitellogenin, a precursor of egg yolk proteins, was transcribed to complementary DNA (cDNAvit) with avian myeloblastosis virus (AMV) reverse transcriptase. Double-stranded cDNA was synthesized with Escherichia coli DNA polymerase I (fragment A) using the self priming ability of the cDNA. Following S1 nuclease digestion the double-stranded cDNA was inserted into the Hind III site of plasmid pBR322 using the poly(dA) . poly(dT) tailing method, and the hybrid molecules were used to transform Escherichia coli chi 1776. Ampicillin-resistant colonies were screened by colony hybridization with 125I-labeled vitellogenen mRNA. Further screening of positive clones was done by agarose gel electrophoresis and in situ hybridization with 125I-labeled vitellogenin mRNA. In addition, plasmid DNA covalently bound to diazotized paper was used to select complementary mRNA sequences. The cloned vitellogenin sequences were shown to hybridize to a mRNA which directs the synthesis of immunoprecipitable vitellogenin when translated in a reticulocyte lysate cell-free system. The length of the inserted cDNA was determined by agarose gel electrophoresis and heteroduplex mapping. The largest insertion was about 2500 base pairs. Restriction mapping indicates that at least three plasmids out of four have different sequences.

Animals↗
PubMed1980

Characterization of cloned complementary DNA covering more than 6000 nucleotides (97%) of avian vitellogenin mRNA.

The messenger RNA coding for chicken vitellogenin, a precursor of the egg-yolk proteins lipovitellin and phosvitin, is synthesized in the liver following estrogen injection. This mRNA is 6600 nucleotides long. We have previously reported the cloning and preliminary characterization of some cDNA fragments representing portions of the vitellogenin mRNA [Biochem. Biophys. Acta, 606, 34--46 (1980)]. In this paper we report the full characterization of a larger series of such clones, representing almost the entire length of the mRNA, by restriction endonuclease mapping, R-loop mapping, RNA-DNA hybridization and by translation in vitro of the RNA which hybridizes to the cloned DNA. From the results we conclude that the chicken vitellogenin mRNA, unlike that of Xenopus laevis, does not vary in sequence over most of its length, although some variations in the cDNA sequences were detected particularly in clones derived from the 3' terminus of the RNA. All sequence variants appear to be present in RNA prepared from single animals. The possible origins of these minor species are discussed. Furthermore, we describe a cDNA clone complementary to an mRNA which is about the same size as vitellogenin mRNA and which codes for an egg yolk protein antigenically related to lipovitellin. This mRNA is synthesized constitutively.

Animals↗
PubMed1978

Genome modification in two lines of baby hamster kidney fibroblasts (BHK-21).

Reasons for the different levels of 5-methyl cytosine encountered in the DNA of two baby hamsters kidney fibroblast lines, BHK-21/C13 and BHK-21/PyY have been investigated. From enzymic studies it does not seem that there are large numbers of potentially methylatable cytosine residues in the C13 line DNA which contains a lower level of 5-methyl cytosine. Rather it is possible that the difference may be due to the reiteration in the PyY strain of certain sequences containing 5-methyl cytosine which simply occur less frequently in the other line.

Cell Line↗
PubMedDate not supplied

The hormonal regulation of uteroglobin gene expression.

Uteroglobin is a small progesterone-binding protein expressed in various organs of the rabbit and other rodents. In the endometrium, the expression of this gene is regulated by progesterone and estrogen whereas in the lung uteroglobin gene expression is regulated only by glucocorticoids. The hormonal regulation of uteroglobin gene expression is therefore a useful system for the study of the differential hormonal regulation of a mammalian gene in differentiated tissues.

Animals↗