Impact of diets rich in unsaturated fatty acids on blood and milk metabolites and relationship with micro RNA and micro RNA-messenger RNA co-expression patterns in Holstein cow mammary gland
Notice bibliographique
Résumé
Abstract: The effect of unsaturated fatty acids (USFA) as dietary supplement on the expression of genes or set of co-expressed genes that eventually direct the expression of phenotypes (blood and milk metabolites) are not fully understood. Considering the importance of USFA for human, different techniques (dietary and genetics) have been used to increase the proportion of beneficial FA in milk. Dietary supplementation with LSO and SFO has been used but it is not clear what residual effects these nutrients have on the physiology of the animal, including blood metabolites and milk components, or for how long effects are active after withdrawal from the diet. In the first part of my Ph.D. study (Chapter 1), I presented general background information, notably on bovine milk, milk fat and its origin, mammary gland transcriptome profiling, naming, classification and importance of FA, factors that inlfunece milk fatty acid composition and blood components. In the second part (Chapter 2), I examined the treatment and post treatment effects of supplementation of cows’ diet with 5% LSO or 5% SFO on milk composition and blood metabolites of lactating Holstein cows. Thirdly (Chapter 3), I determined the relationship between the blood and milk metabolites and high interacting microRNA (miRNA) modules and evaluated mRNA/miRNA co-expression from the mammary gland of the same animals. The mRNA transcriptome analysis identified 1,006 (460 up and 546 down-regulated) and 199 (127 up and 72 down-regulated) genes that were significantly differentially regulated by LSO and SFO, respectively. Meanwhile the miRNA transcriptome analysis detected 14 and 22 miRNAs that were significantly differentially regulated by LSO and SFO, respectively. Since a network of genes and regulatory factors work in concert to influence the phenotypic expression of traits, assessment of gene expression without considering the factors that regulate their activities may not adequately explain the complex biological mechanisms underlying the expression of milk components and blood metabolites. Moreover, miRNA interact with mRNA to regulate their expression and consequently biological processes, so it is important to study their synergistic effects on the phenotypic expression of traits (blood and milk components). Therefore, the relationship between these traits and miRNA modules and also the association of miRNA and mRNA following dietary supplementation with 5% LSO or 5% SFO were studied. In the fouth part (Chapter 3) of my PhD study, I investigated the co-expression patterns of high interacting miRNAs and miRNA-mRNA pairs and the key regulatory network of genes that influence blood and milk phenotypes following dietary supplementation with USFA. Dietary modifications through feeding trials is an effective way to rapidly modify milk fat composition. However, the effects of dietary supplementation are totally revocable when feeding conditions change, coupled with low conversion efficiency of dietary FA into milk USFA due to ruminal biohydrogenation of dietary FA in the rumen of the animal. Furthermore, candidate gene studies have demonstrated that SNP in some key lipogenic genes like diacylglycerol o-acyltransferase 1 (DGAT1), sterol regulatory element binding protein-1 (SREBP1) and stearoyl-CoA desaturase (SCD) influence milk fat composition, which also explains part of the genetic variation of milk fat unsaturation indices seen in Holsteins and Brown Swiss cows. Therefore, I investigated the associations between SNPs on genes that were differentially expressed as a result of dietary supplementation with USFA with de novo synthesized fatty acid profiles of Canadian Holstein cows as the fifth part of my Ph.D. study (Chapter 4). To achieve this, SNPs in genes that were differentially expressed as a result of dietary supplementation with USFA were studied for their association with milk de novo synthesized FA in milk from Holstein cows in 18 herds in Quebec. In conclusion, this study provides insights on the molecular mechanisms that occur in the bovine mammary gland following dietary supplementation with 5% LSO and 5% SFO.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».