Molecular Genetics of Residual Feed Intake and Mitochondrial Function in Cattle
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MOLECULAR GENETICS OF RESIDUAL FEED INTAKE AND MITOCHONDRIAL FUNCTION IN CATTLE By Nadiatur Akmar Zulkifli A thesis submitted to the University of Adelaide in fulfilment of the requirement of the degree of Doctor of Philosophy The University of Adelaide School of Animal and Veterinary Sciences July 2016 TABLE OF CONTENTS Table of Contents ii Index of Figures vii Index of Tables ix Index of Appendices xii Abstract xiii Declaration xvi Acknowledgements xvii Dedication xix Chapter 1 : Literature Review 1 1.1 Introduction 2 1.2 Cattle 3 1.2.1 Jersey cattle 3 1.2.2 Limousin cattle 4 1.2.3 Jersey x Limousin cattle 6 1.2.4 Genetics of cattle 6 1.3 Residual feed intake 7 1.3.1 Residual feed intake as a genetic trait 10 1.3.2 Measurement of feed intake 11 1.3.2.1 Centralised testing facility 12 1.3.2.2 On-farm testing 12 1.3.3.3 Measurement on pasture 12 1.3.3 Genetic correlations for measures of body composition with residual feed intake 13 1.3.4 Quantitative trait loci in residual feed intake 14 1.4 Mechanisms affecting residual feed intake 17 1.4.1 Energy metabolism 17 1.4.2 Mitochondrial function 19 1.4.3 Cellular respiration process 21 ii 1.4.3.1 Glycolyis 21 1.4.3.2 Krebs cycle 24 1.4.3.3 Electron transport chain 26 1.4.3.3.1 Complex I 27 1.4.3.3.2 Complex II 28 1.4.3.3.3 Complex III 28 1.4.3.3.4 Complex IV 29 1.4.3.3.5 Complex V 29 1.4.3.4 Oxidative phosphorylation 31 1.4.3.5 Reactive oxygen species 32 1.4.4 Other known energy pathways affecting residual feed intake 34 1.4.4.1 Uncoupling proteins 34 1.4.4.2 Adenine monophosphate activated protein kinase (AMPK) 34 1.5 Relationship between mitochondrial function and residual feed intake in animals 35 1.5.1 Poultry 35 1.5.2 Pigs 36 1.5.3 Cattle 37 1.6 Summary 38 Chapter 2 : Materials and Methods 40 2.1 QTL mapping of residual feed intake in cattle 41 2.1.1 Cattle QTL mapping experimental design 41 2.1.2 Single Nucleotide Polymorphisms (SNP) experiments 43 2.1.2.1 Selection of candidate genes for SNP detection 43 2.1.2.2 Genomic DNA purification 43 2.1.2.3 DNA concentration 44 2.1.2.4 Primer design 44 2.1.2.5 Polymerase Chain Reaction (PCR) iii condition optimisation 44 2.1.2.6 Gel electrophoresis 46 2.1.2.7 PCR purification 46 2.1.2.8 DNA sequencing 47 2.2 Genotyping 49 2.2.1 High Resolution Melt (HRM) 49 2.2.2 Genotyping analysis 51 2.2.3 Pathway analysis 53 2.3 Mitochondrial enzyme experiments 53 2.3.1 Selection lines 53 2.3.2 Sample collection: Liver 54 2.3.3 Mitochondrial preparation from frozen liver samples 54 2.3.4 Bradford Assay 55 2.3.5 Oxidative phosphorylation enzyme complexes assays 55 2.3.5.1 Complex I Activity 55 2.3.5.2 Complex III Activity 56 2.3.5.3 Complex IV Activity 56 2.3.5.4 Protein carbonyl assay 56 2.3.5.5 Analysis for Biochemical Assay 57 Chapter 3 : Candidate Genes for RFI : Identification and DNA Variants 58 3.1 Introduction 59 3.2 Materials and Methods 60 3.2.1 DNA samples 60 3.2.2 Primer design 61 3.2.3 Polymerase Chain Reaction (PCR) 62 3.2.4 Sequencing 63 3.3 Results 63 3.3.1 Candidate Genes 63 3.3.1.1 Catalase 64 iv 3.3.1.2 Aldolase B 66 3.3.1.3 Adenylate Kinase 1 67 3.3.1.4 Superoxide Dismutase 1 68 3.3.1.5 Succinyl Co A Synthetase 69 3.3.1.6 Superoxide Dismutase 2 71 3.3.1.7 Ghrelin 71 3.3.1.8 NADH Dehydrogenase (Ubiquinone) I Beta Subcomplex, 5, 16kDa 72 3.3.1.9 NADH Dehydrogenase (Ubiquinone) I Alpha Subcomplex, 8, 19kDa 73 3.3.1.10 Hydroxyacyl-CoA Dehydrogenase-β Subunit 73 3.3.2 Sequencing variants 74 3.4 Discussion 80 3.5 Summary 83 Chapter 4 : Candidate Gene Associations 85 4.1 Introduction 86 4.2 Methods 88 4.2.1 Genotyping 88 4.2.1.1 High Resolution Melt (HRM) 89 4.2.1.2 Data analysis 90 4.3 Results 90 4.3.1 High Resolution Melt (HRM) 90 4.3.2 SNP association studies 96 4.3.3 Haplotype effects 105 4.4 Discussion 108 4.5 Summary 114 Chapter 5 : Candidate Gene Pathways and Epistatic Effects 116 5.1 Introduction 117 5.2 Methods 117 5.3 Results 118 v 5.3.1 Pathway analysis 118 5.3.2 Epistatic effects 122 5.3.2.1 Candidate gene epistatic interactions 122 5.3.2.2 Additional epistatic interactions on RFI and fat traits 130 5.4 Discussion 131 5.5 Summary 134 Chapter 6 : Mitochondrial enzyme assays 136 6.1 Introduction 137 6.2 Materials and Methods 139 6.2.1 Liver samples 140 6.2.2 Analysis for biochemical assays 141 6.3 Results 141 6.3.1 Bradford assay 141 6.3.2 Complex I enzyme assay 142 6.3.3 Complex III enzyme assay 144 6.3.4 Complex IV enzyme assay 146 6.3.5 Protein carbonyl assay 148 6.4 Discussion 150 6.5 Summary 155 Chapter 7 : General discussion 156 7.1 Introduction 157 7.2 Residual feed intake and mitochondrial function 160 7.3 Residual feed intake candidate genes 163 7.4 Residual feed intake and body composition 166 7.5 Conclusion 168 Appendices 169 References 195 vi INDEX OF FIGURES Figure 1.1 Relationship between feed intake and the expected weight gain 9 Figure 1.2 Contribution of biological mechanisms to variation in residual feed intake as determined from experiments on divergently selected cattle 19 Figure 1.3 Mitochondria structure 20 Figure 1.4 The reactions of glycolysis convert glucose to pyruvate 23 Figure 1.5 Reactions of the Krebs cycle 26 Figure 1.6 Electron transport chain 30 Figure 2.1 Davies cattle QTL mapping backcross design 42 Figure 3.1 Mechanism of oxidative cellular damage 65 Figure 3.2 Fructose utilisation in the liver showing its interrelationship with glucose and fatty acid metabolism 67 Figure 3.3 Regulation of energy homeostasis by the AMPK system 68 Figure 3.4 The disproportionation of superoxide is a two-step oxidation-reduction reaction that involves the cycling of the copper atom in SOD1 from Cu2+ to Cu+ and back to Cu+2 69 Figure 3.5 Krebs cycle and methylmalonate metabolism 70 Figure 4.1 Melt curve of SOD2SNP3, a transversion SNP with two genotypes, GC and GG 92 Figure 4.2 Melt profile analysis of SOD2SNP3, a transversion SNP with two genotypes, GC and GG 92 Figure 4.3 Melt curve of HADSNP7, a transversion SNP with three genotypes, AT, TT and AA 93 Figure 4.4 Melt profile analysis of HADSNP7, a transversion SNP with three genotypes, AT, TT and AA 93 Figure 4.5 Melt curve of HADSNP2, a transition SNP with three genotypes, AA, GG and AG 94 Figure 4.6 Melt profile analysis of HADSNP2, a transition SNP with three genotypes, AA, GG and AG 94 Figure 6.1 Standard curve at 595 nm for low RFI samples 142 vii Figure 6.2 Correlation between mid-parent RFI EBV and Complex I activity 144 Figure 6.3 Correlation between mid-parent RFI EBV and Complex III activity 146 Figure 6.4 Correlation between mid-parent RFI EBV and Complex IV activity 148 Figure 6.5 Correlation between mid-parent RFI EBV and ROS activity 149 viii INDEX OF TABLES Table 1.1 Heritability estimates for net feed efficiency in different species 11 Table 1.2 Genetic correlation for measures of body composition with residual feed intake 14 Table 1.3 NFE QTL identified in the Davies Jersey x Limousin herd 16 Table 2.1 PCR reagents concentration 45 Table 2.2 Sequencing reagents 47 Table 2.3 High resolution melt reagents concentration 50 Table 3.1 F1 mapping sires and their parents identification number 61 Table 3.2 Primer sets for neighbouring exons 62 Table 3.3 Primer sets for exon > 500bp 62 Table 3.4 Selected candidate genes and their function 64 Table 3.5 DNA variants identified in the candidate genes 75 Table 3.6 Summary of DNA variants found in candidate genes 78 Table 3.7 Synonymous and non-synonymous SNPs 78 Table 4.1 List of genotyped SNPs 89 Table 4.2 Summary data of the 14 genotyped SNPs 91 Table 4.3 Number of progeny with each genotype and allele frequencies 95 Table 4.4 Residual feed intake related traits 96 Table 4.5 Specific fat depot traits for association studies 97 Table 4.6 Traits affected by SNPs without and with MSTN F94L genotype in the model 98 Table 4.7 Number of SNPs affecting each trait with and without MSTN F94L genotype in the model 100 Table 4.8 Fat traits affected by SNPs without and with MSTN F94L genotype in the model 101 Table 4.9 Number of SNPs affecting fat depot trait with and without MSTN F94L genotype in the model 102 ix Table 4.10 SNP effects on daily feed intake (DFI) and residual feed intake (RFI) with and without MSTN F94L genotype in the model 103 Table 4.11 Additional SNPs analysed for effects on RFI with and without MSTN F94L genotype in the model 104 Table 4.12 Additional SNPs with significant effects on residual feed intake with and without MSTN F94L genotype in the model 105 Table 4.13 SNP interactions within genes without MSTN F94L genotype in the model 107 Table 4.14 SNP interactions within genes with MSTN F94L genotype in the model 107 Table 5.1 Protein state interactions 120 Table 5.2 Gene expression interactions 121 Table 5.3 Tests of significance for SNP interactions between candidate genes affecting RFI related traits 125 Table 5.4 Tests of significant for SNP interactions between candidate genes affecting specific fat depot traits 128 Table 5.5 SNP interactions between genes for RFI and DFI with and without the MSTN F94L genotype in the model 129 Table 5.6 Additional SNPs interactions with selected fat traits without MSTN F94L genotype in the model 130 Table 5.7 Additional SNPs interactions with selected fat traits with MSTN F94L genotype in the model 130 Table 6.1 Complex I enzyme activity of high and low residual feed intake animals 142 Table 6.2 Regression analysis for RFI related traits and Complex I enzyme activity with correlation and test of significant slope 143 Table 6.3 Complex III enzyme activity of high and low residual feed intake animals 144 Table 6.4 Regression analysis for RFI