Volume 119, Issue 1, Pages 151-161 (July 2000) Effects of dietary folate on DNA strand breaks within mutation-prone exons of the p53 gene in rat colon Young–In Kim, Shaila Shirwadkar, Sang–Woon Choi, Martina Puchyr, Yang Wang, Joel B. Mason Gastroenterology Volume 119, Issue 1, Pages 151-161 (July 2000) DOI: 10.1053/gast.2000.8518 Copyright © 2000 American Gastroenterological Association Terms and Conditions
Fig. 1 (A) Mean plasma folate concentrations in 3 groups of rats fed different levels of dietary folate. Different letters at each time point indicate statistically significant differences (P < 0.001). (B) Mean colonic mucosal folate concentrations in 3 groups of rats fed different levels of dietary folate. Different letters at each time point indicate statistically significant differences (P < 0.05). (C) Mean plasma homocysteine concentrations, an inverse indicator of folate status, in 3 groups of rats fed different levels of dietary folate. Different letters at each time point indicate statistically significant differences (P < 0.01). Gastroenterology 2000 119, 151-161DOI: (10.1053/gast.2000.8518) Copyright © 2000 American Gastroenterological Association Terms and Conditions
Fig. 2 Effect of dietary folate deficiency and supplementation on DNA strand breaks within exons 5-8 of the p53 gene as assessed by qPCR. In this assay, the decrease in the quantitative recovery of 32P-labeled PCR amplification product is proportional to the extent of DNA lesions present within these exons. Results are expressed as the extent of [32P]qPCR product recovery, defined as a percentage of the control. Different letters at each time point indicate statistically significant differences (P < 0.05). The recovery of [32P]qPCR product in the folate-deficient group decreased progressively over the study period (P < 0.02, linear trend), indicating progressive accumulation of DNA strand breaks within these exons with extended folate deprivation. Gastroenterology 2000 119, 151-161DOI: (10.1053/gast.2000.8518) Copyright © 2000 American Gastroenterological Association Terms and Conditions
Fig. 3 Effect of dietary folate deficiency and supplementation on DNA strand breaks within exons 2-4 of the p53 gene as assessed by qPCR. Results are expressed as the extent of [32P]qPCR product recovery, defined as a percentage of the control. Different letters at each time point indicate statistically significant differences (P < 0.05). Gastroenterology 2000 119, 151-161DOI: (10.1053/gast.2000.8518) Copyright © 2000 American Gastroenterological Association Terms and Conditions
Fig. 4 (A) A representative autoradiogram of steady-state levels of p53 transcript among 3 groups of rats fed different levels of dietary folate at week 5. A 277-bp region in exons 6-7 of the rat p53 gene was amplified by RT-PCR from total RNA of the colonic mucosa. The amplified RT-PCR product from each sample was separated on an agarose gel, transferred to a nylon membrane using Southern blot, and hybridized with an internal oligonucleotide probe. (B) Effect of dietary folate deficiency and supplementation on steady-state levels of p53 transcripts as assessed by semiquantitative RT-PCR. Results are expressed as the percentage change in p53/GAPDH transcript ratios from control. Different letters at each time point indicate statistically significant differences (P < 0.04). Steady-state levels of p53 transcript progressively decreased in rats fed a folate-deficient diet, whereas they progressively increased in rats fed a supplemented diet during the study period (P < 0.05, linear trend). Gastroenterology 2000 119, 151-161DOI: (10.1053/gast.2000.8518) Copyright © 2000 American Gastroenterological Association Terms and Conditions
Fig. 4 (A) A representative autoradiogram of steady-state levels of p53 transcript among 3 groups of rats fed different levels of dietary folate at week 5. A 277-bp region in exons 6-7 of the rat p53 gene was amplified by RT-PCR from total RNA of the colonic mucosa. The amplified RT-PCR product from each sample was separated on an agarose gel, transferred to a nylon membrane using Southern blot, and hybridized with an internal oligonucleotide probe. (B) Effect of dietary folate deficiency and supplementation on steady-state levels of p53 transcripts as assessed by semiquantitative RT-PCR. Results are expressed as the percentage change in p53/GAPDH transcript ratios from control. Different letters at each time point indicate statistically significant differences (P < 0.04). Steady-state levels of p53 transcript progressively decreased in rats fed a folate-deficient diet, whereas they progressively increased in rats fed a supplemented diet during the study period (P < 0.05, linear trend). Gastroenterology 2000 119, 151-161DOI: (10.1053/gast.2000.8518) Copyright © 2000 American Gastroenterological Association Terms and Conditions