Title

Investigating the Presence of Circadian Rhythms in Colon Regeneration

Type of Proposal

Oral Presentation

Start Date

22-3-2018 9:20 AM

End Date

22-3-2018 10:40 AM

Location

Alumni Auditorium C

Faculty

Faculty of Arts, Humanities and Social Sciences

Faculty Sponsor

Dr. Phillip Karpowicz

Abstract/Description of Original Work

Little is known about the regenerative response in the colon as directed by the circadian clock. The latter is an evolutionary molecular oscillator which generates periodic 24-hour (circadian) rhythms in division and that is synchronized with daily external cues, such as photoperiod and temperature variations. This is troubling, since improper intestinal stem cell proliferation is 20 times more likely to lead to cancer in the human large intestine than in the human small intestine. We propose to characterize the circadian rhythm in colon regeneration of wild type mice following Dextran Sulfate Sodium (DSS)-induced colitis to create damage conditions in the large intestine, and we hypothesize that the damaged colon will still have circadian rhythms. Ten-micron sections of three wild type mouse intestine samples treated with DSS have been gathered at six different time points. These sections have been stained using antibody to pHH3, which labels cells undergoing mitosis, and DAPI, which labels the nuclei of all living cells. Fluorescence microscopy quantification is now being used to assess the number of dividing cells to the total number of cells in 10-20 crypts for the proximal and distal regions of the small intestine and the colon of each sample. Undamaged intestinal tissue should, and so far, has shown to have low pHH3 staining throughout, indicating undamaged intestinal tissue has a lower rate of regeneration. Damaged intestinal tissue should display more pHH3 staining. Quantification of the ratio of pHH3-stained cells to the total number DAPI-stained cells at 6 different time points that show repetitive 24-hour patterns will determine the presence of circadian rhythm mediation. Knowledge of circadian rhythms of the colon in damaged and undamaged conditions will supplement our understanding of regeneration of the intestine as a whole, allowing for improved timing of treatments of gastrointestinal disorders.

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Mar 22nd, 9:20 AM Mar 22nd, 10:40 AM

Investigating the Presence of Circadian Rhythms in Colon Regeneration

Alumni Auditorium C

Little is known about the regenerative response in the colon as directed by the circadian clock. The latter is an evolutionary molecular oscillator which generates periodic 24-hour (circadian) rhythms in division and that is synchronized with daily external cues, such as photoperiod and temperature variations. This is troubling, since improper intestinal stem cell proliferation is 20 times more likely to lead to cancer in the human large intestine than in the human small intestine. We propose to characterize the circadian rhythm in colon regeneration of wild type mice following Dextran Sulfate Sodium (DSS)-induced colitis to create damage conditions in the large intestine, and we hypothesize that the damaged colon will still have circadian rhythms. Ten-micron sections of three wild type mouse intestine samples treated with DSS have been gathered at six different time points. These sections have been stained using antibody to pHH3, which labels cells undergoing mitosis, and DAPI, which labels the nuclei of all living cells. Fluorescence microscopy quantification is now being used to assess the number of dividing cells to the total number of cells in 10-20 crypts for the proximal and distal regions of the small intestine and the colon of each sample. Undamaged intestinal tissue should, and so far, has shown to have low pHH3 staining throughout, indicating undamaged intestinal tissue has a lower rate of regeneration. Damaged intestinal tissue should display more pHH3 staining. Quantification of the ratio of pHH3-stained cells to the total number DAPI-stained cells at 6 different time points that show repetitive 24-hour patterns will determine the presence of circadian rhythm mediation. Knowledge of circadian rhythms of the colon in damaged and undamaged conditions will supplement our understanding of regeneration of the intestine as a whole, allowing for improved timing of treatments of gastrointestinal disorders.