The aim of the present study was to investigate the effect of a triathlon (3.8 km swim, 180 km cycle, 42,2 km run) on the genomic stability of nine highly trained non-
professional athletes.
Therefore, the SCE assay, a relevant biological response marker for genotoxicity in
human biomonitoring studies [PENDZICH et al., 1997] was performed using peripheral
lymphocytes, on account of their effortless accessibility [WILKOSCY and RYNARD,
1990].
Duplicate lymphocyte cell cultures, of each participant, were incubated for 72 h (37°C, 5% CO2) according to a short-term human lymphocyte cell culture. For each participant at least 50 metaphases, containing 43-46 chromosomes were scored, to evaluate the mean SCE frequency. The number of SCEs per cell was calculated to a chromosome set of a normal diploid human cell, containing 46 chromosomes.
In the present study the alteration of SCE frequency, 48 h pre- and 24 h postrace was evaluated. As an additional endpoint Top 5 HFCs (highest five absolute SCE means) were assayed. It could be demonstrated that both the total mean SCE frequency and the mean Top 5 HFC frequency (n=9) 24 h postrace were significantly decreased (*p< 0.05) compared to 48 h prerace values. Considering the training status, a significant negative correlation between the relative SCE changes before and after the triathlon was observed for the cycling training per week (km) (r=-0.86; **p< 0.01), the running training per week (km) (r=-0.90; *p< 0.05)
as well as for the weekly net exercise training time (h) (r=-0.89; *p< 0.05). The relative changes of Top 5 HFCs before and after the race correlated significantly with the cycling training per week (km) (r=-0.79; *p< 0.05) and with the body mass index
(kg/m2) (r=-0.69; *p< 0.05). These findings suggest the existence of endogenous repair mechanisms which seem to prevent DNA damage.
Table of Contents
1. INTRODUCTION
2. BACKGROUND
2.1. Human lymphocytes
2.2. Cell cycle
2.2.1. Interphase
2.2.1.1. Checkpoints
2.2.2. Mitosis
2.3. Sister Chromatid Exchange
2.3.1. Mechanism of SCE
2.3.2. Scientific significance of the SCE assay
2.3.3. SCE inducing agents
2.3.4. Persistence of SCE
2.3.5. Historical background
2.3.6. BrdU incorporation and visualization of SCEs
2.3.7. The role of cell culture components
2.3.8. Factors potentially influencing SCE frequency
2.3.8.1. Culture factors
2.3.8.2. Biological and physiological factors
2.4. The Correlation between strenuous endurance exercise and genotoxicity
2.4.1. Reactive oxygen species (ROS) and physical exercise
2.4.2. Exercise-induced oxidative stress
2.4.3. Exercise-induced DNA damage
2.4.3.1. Relation to oxygen consumption
2.4.3.2. Relation to a single bout of exercise
2.4.4. Exercise-induced adaptation
2.4.5. Regular physical exercise
3. MATERIALS AND METHODS
3.1. Project description
3.2. Subjects
3.2.1. Inclusion criteria
3.2.2. Exclusion criteria
3.2.2.1. Supplementation guidelines
3.3 Equipment for the SCE assay
3.4. Reagents of the SCE assay
3.4.1. Manufacturing processes and storage of reagents for SCE assay
3.5. Basic assay approach
3.6. Assay description
3.7. Blood collection
3.8. Sister Chromatid Exchange assay
3.9. Statistical analysis
3.10. Guidelines for microscopic assessment
3.11. Top five HFCs
4. RESULTS AND DISCUSSION
4.1. Study design
4.2. Subjects characteristics
4.3. Preliminary testing
4.4. Assay criteria
4.5. Distribution of evaluated SCEs per cell
4.6. Abs. SCEs
4.6.1. Descriptive statistics
4.6.2. Single means of abs. SCEs
4.6.3.Total mean abs. SCEs
4.7. Top 5 HFCs
4.7.1. Descriptive statistics
4.7.2. Single means of Top 5 HFCs
4.7.3. Total mean Top 5 HFCs
4.8. Correlations
4.8.1.Abs. SCEs
4.8.2. Top 5 HFCs
5. CONCLUSION
6. SUMMARY
7. ZUSAMMENFASSUNG
8. REFERENCES
9. APPENDIX
9.1. Single values of participant 36
9.2. Single values of participant 37
9.3. Single values of participant 39
9.4. Single values of participant 41
9.5. Single values of participant 42
9.6. Single values of participant 43
9.7. Single values of participant 46
9.8. Single values of participant 47
9.9. Single values of participant 48
Research Objectives and Topics
This study aims to investigate the effects of a single bout of strenuous exercise—specifically an Ironman triathlon—on the genomic stability of highly trained athletes. The research focuses on whether such extreme endurance activity induces cytogenetic damage by evaluating the alteration of Sister Chromatid Exchange (SCE) frequency in peripheral blood lymphocytes.
- Impact of ultra-endurance exercise on genomic stability
- Analysis of Sister Chromatid Exchange (SCE) as a biological marker for DNA damage
- Role of exercise-induced oxidative stress in peripheral lymphocytes
- Correlation between different training levels and DNA damage markers
- Assessment of endogenous adaptive responses and repair mechanisms in trained athletes
Excerpt from the Book
2.3. Sister Chromatid Exchange
A natural process, spontaneously proceeding at certain rates in all cells during the normal DNA replication [HAAF and SCHMID, 1991; SONODA et al., 1999], involving a four-fold polynucleotide strand breakage and reunion of each sister chromatid of a chromosome at apparently homologous regions, is called sister chromatid exchange [KANG et al., 1997].
Although this event, a reciprocal interchange by homologous recombination, is considered to be accurate [WILSON and THOMPSON, 2007], not resulting in alterations of overall chromosome morphology [PERRY and EVANS, 1975], cell viability, cell function, or adverse health outcomes, an elevated value of SCEs indicates that cells have been exposed to a mutagen [WILCOSKY and RYNARD, 1990].
SCE induction raises to a maximum at the onset of DNA synthesis, but declines to zero at the end of S-phase, suggesting that SCEs emerge at the replication point [TAWN and HOLDSWORTH, 1992], resulting in an absolute exigency of DNA replication for SCE formation [CARRANO and NATARAJAN, 1988].
The exact molecular mechanisms responsible for the genesis of SCEs are still inconclusive [WILSON and THOMPSON, 2007], but hypotheses have implicated the mechanics of DNA synthesis in SCE formation [ALBERTINI et al., 1985].
Summary of Chapters
1. INTRODUCTION: Outlines the health implications of exhaustive exercise and establishes the research goal of assessing risk via SCE analysis in triathletes.
2. BACKGROUND: Provides a theoretical overview of lymphocytes, the cell cycle, the mechanisms of SCE, and the correlation between endurance exercise and genotoxicity.
3. MATERIALS AND METHODS: Details the study design, participant criteria, and the specific laboratory protocols used for the SCE assay and statistical analysis.
4. RESULTS AND DISCUSSION: Presents the statistical data gathered from the athletes and discusses the findings regarding SCE frequency and training correlations.
5. CONCLUSION: Synthesizes the study results, confirming that a significant decrease in SCE frequency after the race suggests adaptive endogenous repair mechanisms.
6. SUMMARY: Summarizes the study’s purpose, methodology, and the key observation that DNA damage markers were significantly decreased post-race.
7. ZUSAMMENFASSUNG: Die Zusammenfassung der Arbeit in deutscher Sprache, entsprechend der wissenschaftlichen Tradition.
8. REFERENCES: Lists the academic literature and scientific papers cited throughout the diploma thesis.
9. APPENDIX: Contains the individual raw data tables for each participant in the study.
Keywords
Sister Chromatid Exchange, SCE, Ironman triathlon, genotoxicity, oxidative stress, DNA damage, lymphocytes, endurance exercise, genomic stability, adaptive response, DNA repair, biomonitoring, training status, reactive oxygen species, ROS
Frequently Asked Questions
What is the primary objective of this research?
The study aims to evaluate whether a single bout of ultra-endurance exercise, specifically an Ironman triathlon, causes DNA damage in highly trained athletes by measuring changes in SCE frequency.
Why was the Sister Chromatid Exchange (SCE) assay chosen?
The SCE assay was selected as a sensitive and established biological indicator of DNA damage and genomic instability in human epidemiology studies due to the easy accessibility of peripheral lymphocytes.
What were the major findings regarding DNA damage in triathletes?
Contrary to the hypothesis that exhaustive exercise would increase DNA damage, the study found a significant decrease in mean absolute SCE frequencies 24 hours after the triathlon, suggesting an upregulation of protective adaptive mechanisms.
What research methods were utilized?
The research involved a prospective study of 9 male endurance-trained athletes. Blood samples were collected 48 hours before and 24 hours after the competition and processed using lymphocyte cell culture and Giemsa staining to visualize SCEs.
How is the training status correlated with DNA damage?
The study observed significant negative correlations between the relative changes in SCE/HFC frequencies and specific training metrics, such as weekly cycling or running distances, indicating that higher training levels might enhance the adaptive response.
What are the key themes addressed in the literature review?
The background covers the cell cycle, mechanisms of SCE, scientific significance of the SCE assay, the relationship between oxidative stress and exercise, and the concept of exercise-induced adaptation.
Are the results of this study consistent with previous research?
The study supports findings from other researchers that intensive endurance exercise does not necessarily lead to sustained cytogenetic damage, likely due to an efficient endogenous antioxidant defense system.
What is a "Top 5 HFC" and why is it used?
Top 5 HFCs refer to the highest five SCE means per cell. They are used as an additional endpoint to improve the sensitivity of the analysis, as high-frequency cells represent a subset of long-lived lymphocytes that may have accumulated more damage.
Does the study conclude that triathlons are harmful to DNA?
No, the study suggests that while exhaustive exercise triggers oxidative stress, the body of a highly trained athlete responds with adaptive processes that prevent long-term genomic instability.
- Quote paper
- Mag.rer.nat. Marlies Meisel (Author), 2007, Alterations of the Sister Chromatid Exchange frequency in peripheral lymphocytes caused by an Ironman triathlon, Munich, GRIN Verlag, https://www.hausarbeiten.de/document/86371
