Contributions of direct incorporation from diet and microbial amino acids to protein synthesis in Nile tilapia
By S. Newsome, M. Fogel, L. Kelly, C. Martínez Del Rio. 2011
128 citations recorded by the source corpus.
Summary 1. Further advancement in the use of stable isotope analysis in animal ecology and physiology requires a better understanding of how organisms incorporate the macromolecular elements they consume into the tissues they biosynthesize. 2. Mixing models used to infer diets from isotopic data assume that assimilated macromolecules are dissembled into elements and then reassembled in animal tissues. 3. To test this assumption, we fed Nile tilapia diets with contrasting levels of protein and in which the carbon isotopic composition of protein differed from that of other macronutrients (carbohydrates and lipids). We then analysed the d 13 C values of individual tilapia amino acids using compound-specific stable isotope analysis (CSIA). 4. The incorporation of dietary protein carbon was dependent on dietary protein content and on each amino acid’s biosynthesis pathway. The d 13 C values of glycolytic amino acids, such as glycine, serine and alanine, had roughly constant values that reflected a large contribution of dietary carbohydrates and a small contribution of dietary protein. The d 13 C values of aspartate and glutamate that are biosynthesized from Krebs cycle intermediaries paralleled bulk diet. 5. The d 13 C values of indispensable amino acids resembled that of carbohydrates at low protein intakes but tended asymptotically to that of the d 13 C values of their corresponding dietary amino acid as protein intake increased. This pattern is consistent with assimilation of indispensable amino acids of microbial origin by tilapias fed low protein food. 6. Our results suggest that the assumptions of mixing models are sound in situations where omnivores consume protein-deficient diets, as the elemental constituents used to biosynthesize amino acids in tissues may be derived from various ingested macromolecules (e.g. protein, carbohydrates, or lipids) and their elemental components. In contrast, for omnivores that consume sufficient amounts of protein, macromolecular (e.g. protein) routing likely occurs and mixing model assumptions are violated. 7. Our study shows that CSIA is a novel method to quantify the contribution of symbiotic microbes to the amino acid homeostasis of animals.
Subfields: Ecology, Global and Planetary Change
View Paper: https://www.semanticscholar.org/paper/9c11944057a84bc91e19d470ab22c135a3a4389f
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Citations in the corpus
- Embracing variability in amino acid δ15N fractionation: mechanisms, implications, and applications for trophic ecology (2016, background): “De novo synthesized source AAs from gut microbes can be an important secondary supply of source AAs, particularly in organisms feeding on low protein diets (McBee 1971, Harris 1993, Clements et al. 2009, Newsome et al. 2011).”
- Macronutrient-based model for dietary carbon routing in bone collagen and bioapatite (2012, background): “However, evidence from single amino acid analyses and dietary feeding experiments, support a largely routed model (Hare et al. 1991; Ambrose et al. 1997; Schwarcz 2001; Howland et al. 2003; Corr et al. 2005; Jim et al. 2006; Froehle et al. 2010; Newsome et al. 2011).”
- Use of Probiotics in Diets of Tilapia (2011, background): “[44] found that tilapia appeared to be able to acquire their essential amino acid requirements directly from the GI microbiota when dietary sources were insufficient.”