Title Page
Contents
Abbreviations 10
I. Introduction 11
II. Background 13
2.1. Telomere Structure 13
2.2. Telomere Function 15
2.3. Telomerase and Telomere Equilibrium 15
2.4. Telomeric Variations and Causes 18
2.5. Factors Affecting at the Genetic Level 19
2.5.1. Species 19
2.5.2. Inheritance or Heritability 19
2.5.3. Breed/race and Sex 20
2.5.4. Telomere Shortening Rate (TSR) 21
2.5.5. Telomerase Activity 21
2.5.6. Tissue Types 22
2.6. Factors Affecting at the Epigenetic Level 24
2.6.1. Environmental Factors 24
2.6.2. Stochastic Factors 27
2.7. Telomere Length and Individual Lifespan 28
2.8. Telomeres as a measure of Biological Quality of an Individual 30
2.9. Telomere Quantification 31
III. Materials & Methods 35
3.1. Research Treatments 35
3.1.1. Breed and Sex 35
3.1.2. Age 35
3.1.3. Stocking Density 35
3.1.4. Living/Housing Conditions 36
3.1.5. Antioxidants 36
3.1.6. Energy Restriction and Restricted Feed Intake 37
3.1.7. Oxidative Stress 37
3.2. Preparation of Cells 37
3.3. Telomere DNA Probe 38
3.4. Quantitative Fluorescent In Situ Hybridization 39
3.5. Statistical Analysis 40
IV. Results and Discussion 42
4.1. Genetic Determinants affecting Telomere Amount 43
4.1.1. Breed and Sex 43
4.2. Epigenetic Determinants affecting Telomere Amount 47
4.2.1. Environmental Factors 47
4.2.2. Stochastic Factors 53
V. Summary 64
VI. References 67
Acknowledgements 80
Table 1. Telomere biology of some organisms 23
Table 2. Amount of telomeric DNA (ATD) and stocking density 52
Table 3. Amount of telomeric DNA (ATD) and living or housing conditions 54
Table 4. Amount of Telomeric DNA and antioxidants 56
Table 5. Amount of Telomeric DNA and energy restriction and restricted feed intake 58
Table 6. Amount of Telomeric DNA and oxidative stress 60
Fig.1. Vertebrate Telomere Structure. 14
Fig.2. A two stage telomere/telomerase model of cellular aging and cancer in humans. 17
Fig.3. Quantification of telomere amount by the IQ FISH. 41
Fig.4. Amount of telomeric DNA and breed. 45
Fig.5. Amount of telomeric DNA and sex. 46
Fig.6. Amount of telomeric DNA and age. 48
Fig.7. Telomere shortening rate (TSR) of different age groups. 49
Fig.8. Telomere shortening rate (TSR) and stocking density. 52
Fig.9. Telomere shortening rate (TSR) and living or housing conditions. 54
Fig.10. Telomere shortening rate (TSR) and antioxidants. 56
Fig.11. Telomere shortening rate (TSR) and energy restriction/restricted feed intake. 58
Fig.12. Telomere shortening rate (TSR) and oxidative stress. 60