Molecular and biochemical analyses of the role of nutrition and body condition in Holstein cows and the developing fetus

Aboragah, Ahmad Abdullah A

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https://hdl.handle.net/2142/117589 Copy

Description

Title

Molecular and biochemical analyses of the role of nutrition and body condition in Holstein cows and the developing fetus

Author(s)

Aboragah, Ahmad Abdullah A

Issue Date

2022-12-02

Director of Research (if dissertation) or Advisor (if thesis)

Loor, Juan

Doctoral Committee Chair(s)

Loor, Juan

Committee Member(s)

• Pan, Yuan-Xiang
• McCann, Joshua
• Alolimy, Ahmed

Department of Study

Animal Sciences

Discipline

Animal Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

Gestation, mTOR signaling, one-carbon metabolism

Abstract

The objective of the studies in this dissertation was to use molecular (mRNA, protein, metabolites, microbiota, DNA methylation) and biochemical [cystathionine-β-synthase (CBS), betaine-homocysteine S-methyltransferase (BHMT), gamma-glutamyl transferase, glutathione] correlates of tissue function to assess the impact of body condition and stage of lactation on the cow and the fetus. Targets evaluated were the mTOR signaling, one-carbon metabolism, and antioxidant mechanisms in tissues, and microbiota in the vagina and uterine. In the first objective, term uteroplacental tissue from 22 multiparous Holstein cows retrospectively divided by prepartal BCS into high BCS (HBCS  3.25; n = 9) or normal BCS (NBCS  3.17; n = 13) was used for analyses. After natural delivery, 4 placentomes per cow were collected and used for analyses. Compared with NBCS, dry matter intake (DMI) was greater in the prepartum for HBCS cows, but neither birth calf weight nor DMI or milk production postpartum differed. Placental translation initiation factor eIF2a (p-eIF2a:total eIF2a) was upregulated and the BCKDH enzyme complex downregulated in HBCS cows, suggesting greater protein synthetic capacity driven in part by sparing of the catabolism of branched-chain amino acids. There was greater concentration of betaine and lower concentrations of dimethylglycine, cystathionine, hypotaurine, and cysteine in the HBCS placenta suggesting reduced flux through BHMT and transsulfuration pathway. In the second objective, cows calving at NBCS were used to study temporal changes in microbiota profiles (16S rRNA sequencing) in the vagina during the periparturient period and endometrium after calving. Vaginal swabs were collected on days -15, +15, and +30 relative to parturition, whereas endometrial swabs were collected on days 0, +4, and +30 after parturition. In the vagina, there was a lack of difference based on beta diversity level with only a significant difference in microbiota diversity in the Chao1 alpha diversity index. In contrast, beta diversity analysis (but not Chao1) revealed differences in microbiota in the endometrium on day 0 after calving. At the genus level, Streptococcus, Family XIII ADokpp group, and unculture_Bacteriodales_bacterium were in greater abundance in the endometrium on day 0 compared with days +4 and +30, suggesting a greater abundance of pathogenic bacteria likely due to opening of the cervix during parturition. In the third objective, molecular correlates of development and function were studied in the liver, placentome, and fetal liver of Holstein dairy cows sacrificed at mid-gestation (Mid-G= 8 cows) and late-gestation (late-G=5 cows). The protein abundance of p-RPS6 was greater in the placentome at Mid-G suggesting a potential down-regulation of protein synthesis. In contrast, the protein abundance of GSTM1 (glutathione-related detoxification enzyme) and HSP-70 (stress-triggered protein) was greater in the placentome at late-G suggesting a potential involvement of both proteins in anti-stress mechanisms. Protein abundance of AKT and some mTOR pathway components was greater in the fetal liver at Mid-G suggesting a potential increase in insulin and/or growth factor signaling to activate cellular mechanisms associated with cell growth, proliferation, and/or metabolism. In the last objective, molecular correlates of tissue development (n = 6 fetuses/tissue) were evaluated in liver, intestine, and hind-leg muscle from fetuses collected at slaughter from clinically-healthy lactating multiparous Holstein dairy cows (37 ± 6 kg milk/d, 100 ± 3 d of gestation). The fetal liver had a greater protein abundance of amino acid transporters, insulin-induced glucose transport, p-AKT and p-eEF2 suggesting this organ has a more active protein synthesis machinery relative to the intestine and muscle. Other unique features of the fetal liver included a marked capacity for fatty acid oxidation (mRNA abundance of PPARA, CPT1A, HMGCS2), one-carbon metabolism activity (CBS, BHMT, and MTR), glutathione metabolism (GPX1), and non-insulin dependent glucose transport (SLC2A1). The intestine had greater protein abundance of p-mTOR, BCKDK, mRNA abundance of CDP-choline pathway components, and concentrations of phosphoethanolamine (precursor of phosphatidylethanolamine). These data suggested greater capacity for protein synthesis and phospholipid synthesis. The mRNA abundance suggested a greater capacity for uptake of carnitine (SLC22A5), glutamate (SLC1A1), and other non-essential amino acids (SLC7A8, SLC38A7). In addition, the 13-fold greater abundance of the Na-dependent transporter (SLC5A1) agreed with its known function in nonruminants as primary mediator of intestinal dietary glucose and galactose uptake. Activation of the antioxidant transcription factor NFE2L2 (p-NFE2L2:NFE2L2) was ~10-fold greater in muscle than liver or intestine. This underscores not only the essentiality of antioxidant mechanisms in the developing muscle, but that the NFE2L2 pathway (as in non-ruminants) regulates glutathione-related antioxidant mechanisms. The 2-fold greater abundance of a mitochondrial amino acid transporter (SLC25A29) along with greater concentrations of glycolytic intermediates, lower lactate, and lower leucine corresponded with greater activation of p-eEF2 suggesting a more active anabolic state. These data contrasted with the ~20-fold greater mRNA abundance of a key regulator of muscle mass (TRIM63). The fact that another key ubiquitin ligase (UBE2G) was also markedly greater in fetal muscle seemed to underscore a delicate balance between protein synthesis and degradation. In summary, the present data indicated that key organs of the cow and the fetus are equipped to respond to external cues such as nutrient supply in part through molecular mechanisms. Future studies could address how environmental inputs such as increases in specific nutrients or stressful periods (e.g. heat stress, weaning) alter the pathways studied, and how they can be manipulated to obtain positive outcomes on the cow and the calf.

Graduation Semester

2022-12

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Ahmad Aboragah

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