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Biomedical subjects

R A Flickinger

Publications and source records attributed to R A Flickinger.

At least 37 records · Page 2Linked to original sources
PubMed1976

Effect of rate of replication upon transcription in chick embryo limb bud mesenchyme cells in organ culture.

In partially synchronized organ cultures of limb bud mesenchyme cells of the 3 1/2-day chick embryo the net accumulation of RNA per cell, including DNA-like RNA, is greater than in randomly dividing cells. Based on levels of newly synthesized DNA, RNA accumulation is greater in the last half of the S period when the rate of DNA synthesis is slower. The ratio of newly synthesized RNA, including DNA-like RNA, to newly.synthesized DNA, is also increased when the rate of DNA replication is reduced with cytosine arabinoside and hydroxyurea. The proportion of newly synthesized non-histone protein to total protein in the chromatin increased with a slower rate of DNA replication and this may account for the augmented transcription. At equivalent levels of inhibition of protein synthesis with the arginine analogue, canavanine, and cycloheximide, it was found that canavanine was more effective in reducing the rate of DNA replication. This suggests that histone synthesis plays a role in controlling the rate of DNA replication. The importance of such findings is that a difference in rate of replication of the same DNA sequences in two cells could cause differential transcription resulting in these cells expressing diverse patterns of cell differentiation.

Animals↗
PubMed1975

The effect of 5-bromodeoxyuridine on chick embryo limb bud mesenchyme in organ culture.

The thymidine analogue 5-bromodeoxyuridine (BrdU) prevents chondrogenesis in organ cultures of limb bud mesenchyme of 3 1/2 day chick embryos. The biologically active levels of BrdU inhibit both DNA and RNA synthesis, but the synthesis of methylated RNA is inhibited less than that of unmethylated RNA. If cell division is partially synchronized the ratio of incorporation of BrdU to thymidine is greater during the first few minutes of the S period than for unsynchronized cells. The results suggest that BrdU may be preferntially incorporated into the starting points of replicons and that this may affect subsequent transcription necessary for chondrogenesis.

Adenosine↗
PubMed1972

Collagen synthesis in Xenopus oocytes after injection of nuclear RNA of frog embryos.

A messenger RNA fraction from polysomes of frog larvae or RNA preparations from isolated nuclei of developing frog embryos were injected into growing Xenopus laevis oocytes that were incubated with labeled proline. Column chromatography of protein hydrolyzates revealed labeled hydroxyproline after injection of the messenger RNA fraction and neurula nuclear RNA, indicating that the injected material had promoted collagen synthesis.

Animals↗