Natural abundance stable carbon isotope evidence for the routing and de novo synthesis of bone FA and cholesterol

Abstract

This research reported in this paper investigated the relationship between diet and bone FA and cholesterol in rats raised on a variety of isotopically controlled diets comprising 20% C3 or C4 protein (casein) and C3 and/or C4 nonprotein or energy (sucrose, starch, and oil) macronutrients. Compound-specific stable carbon isotope analysis (delta13C) was performed on the FA (16:0, 18:0, 18:1, and 18:2) and cholesterol isolated from the diet (n = 4) and bone (n = 8) of these animals. The dietary signals reflected by the bone lipids were investigated using linear regression analysis. delta13C values of bone cholesterol and stearic (18:0) acid were shown to reflect whole-diet delta13C values, whereas the delta13C values of bone palmitic (16:0), oleic (18:1), and linoleic (18:2) acids reflected dietary FA delta13C values. Dietary signal differences are a result of the balance between direct incorporation (or routing) and de novo synthesis of each of these bone lipids. Estimates of the degree of routing of these bone lipids gleaned from correlations between delta13C(dlipid-wdiet) (= delta13C(diet lipid) - delta13C(whole diet)) spacings and delta13C(blipid-wdiet) (= delta13C(bone lipid) - delta13C(whole diet)) fractionations demonstrated that the extent of routing, where 18:2 > 16:0 > 18:1 > 18:0 > cholesterol, reflected the relative abundances of these lipids in the diet. These findings provide the basis for more accurate insights into diet when the delta13C analysis of bone fatty FA or cholesterol is employed.

Compound-specific isotopes of fatty acids as indicators of trophic interactions in the East China Sea ecosystem

“…This fi nding is consistent with the relative depletion in 13 C that occurs during lipid biosynthesis compared with other biochemical pathways (Jim et al, 2003). Figure 2 shows the diff erence in δ 13 C values between total organic carbon and individual fatty acids (C16:0 and C22:6n3).…”

“…Statistical analyses of the entire fatty acid profi le may resolve this problem (Jim et al, 2003). Zooplanktivores (such as Acetes chinensis and T .…”

“…The 16:0, 18:0, 18:1n9, 20:1n7 and 22:1n9 fatty acids are non-essential fatty acids (non-EFAs) that can be synthesized de novo by the Δ9 desaturase enzyme, which inserts a double bond at the ninth carbon from the carboxyl end (Jim et al, 2003). The variation in non-EFA carbon isotopes among diff erent species has a smaller range, which may be due to their utilization of similar organic materials and the same biosynthetic process.…”

Heterotrophic and autotrophic assimilation of fatty acids by two scleractinian corals, Montastraea faveolata and Porites astreoides

“…This mass balance model assumes that the transfer of the specific fatty acids from the zooxanthellae via translocation to the host, and from external food sources through heterotrophic feeding, both occur with little (, 1% propagated experimental error) or no isotopic fractionation and that there is no endogenous synthesis of these particular fatty acids. For EFAs (including DHA, EPA, and ARA) and C 16:0 SAFA, minimal isotopic fractionations occur during translocation in symbiotic associations (Johnston et al 1995;Treignier et al 2009) and during direct assimilation from external food sources by heterotrophs (Rieley et al 1999;Jim et al 2003). The second assumption is also valid for EFAs, as invertebrates are generally unable to endogenously synthesize EFAs in any appreciable quantity (Bell et al 2007).…”

Short- and long-term foraging and foddering strategies of domesticated animals from Qasr Ibrim, Egypt

“…It is through controlled feeding experiments that further understanding of the relationship between dietary macronutrients and d 13 C values of the bone components have been achieved [2,39,40,67,68]. These studies suggest that the essential amino acids are preferentially routed directly from dietary protein.…”