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LC-PUFA biosynthesis in rainbow trout is substrate limited: use of the whole body fatty acid balance method and different 18:3n-3/18:2n-6 ratios.
Lipids 2011; 46(12):1111-27L

Abstract

Five experimental diets with constant total C(18) PUFA and varying 18:3n-3/18:2n-6 ratios were fed to rainbow trout over an entire production cycle. The whole-body fatty acid balance method demonstrated a clear trend of progressively reduced fatty acid bioconversion activity along the n-3 and n-6 pathways, up to the production of 20:5n-3 and 20:4n-6, respectively. This suggests that the pathway exhibits a "funnel like" progression of activity rather than the existence of a single rate limiting step. The production of 22:5n-3 and 22:6n-3 was more active than that of 20:5n-3. However, despite this trend in reduced apparent in vivo net enzyme activity, the efficiency of the various bioconversion steps (measured as % of bioconverted substrate) confirmed an opposing trend. A 3.2-fold higher Δ-6 desaturase affinity towards 18:3n-3 over 18:2n-6 and an 8-fold greater Δ-5 desaturase affinity towards 20:4n-3 over 20:3n-6 were recorded. The main results of the study were that (1) rainbow trout are quite efficient at bioconverting 18:3n-3 to 22:6n-3, and (2) the LC-PUFA biosynthetic pathway is substrate limited. Fillet n-3 LC-PUFA concentrations increased with the increasing dietary supply of 18:3n-3. Despite an almost identical dietary supply of n-3 LC-PUFA, originating from the fish meal fraction of the diets, the fillets of trout fed the diet richest in 18:3n-3 were 2-fold higher in n-3 LC-PUFA than fish fed low 18:3n-3 diets. Nevertheless, fillets of trout fed a fish oil control diet contained more than double the amount of n-3 LC-PUFA compared to fish fed the diets richest in 18:3n-3.

Authors+Show Affiliations

School of Life and Environmental Sciences, Deakin University, Warrnambool, VIC, Australia.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

21892784

Citation

Thanuthong, T, et al. "LC-PUFA Biosynthesis in Rainbow Trout Is Substrate Limited: Use of the Whole Body Fatty Acid Balance Method and Different 18:3n-3/18:2n-6 Ratios." Lipids, vol. 46, no. 12, 2011, pp. 1111-27.
Thanuthong T, Francis DS, Senadheera SP, et al. LC-PUFA biosynthesis in rainbow trout is substrate limited: use of the whole body fatty acid balance method and different 18:3n-3/18:2n-6 ratios. Lipids. 2011;46(12):1111-27.
Thanuthong, T., Francis, D. S., Senadheera, S. P., Jones, P. L., & Turchini, G. M. (2011). LC-PUFA biosynthesis in rainbow trout is substrate limited: use of the whole body fatty acid balance method and different 18:3n-3/18:2n-6 ratios. Lipids, 46(12), pp. 1111-27. doi:10.1007/s11745-011-3607-4.
Thanuthong T, et al. LC-PUFA Biosynthesis in Rainbow Trout Is Substrate Limited: Use of the Whole Body Fatty Acid Balance Method and Different 18:3n-3/18:2n-6 Ratios. Lipids. 2011;46(12):1111-27. PubMed PMID: 21892784.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - LC-PUFA biosynthesis in rainbow trout is substrate limited: use of the whole body fatty acid balance method and different 18:3n-3/18:2n-6 ratios. AU - Thanuthong,T, AU - Francis,D S, AU - Senadheera,S P S D, AU - Jones,P L, AU - Turchini,G M, Y1 - 2011/09/04/ PY - 2011/06/09/received PY - 2011/08/11/accepted PY - 2011/9/6/entrez PY - 2011/9/6/pubmed PY - 2012/3/1/medline SP - 1111 EP - 27 JF - Lipids JO - Lipids VL - 46 IS - 12 N2 - Five experimental diets with constant total C(18) PUFA and varying 18:3n-3/18:2n-6 ratios were fed to rainbow trout over an entire production cycle. The whole-body fatty acid balance method demonstrated a clear trend of progressively reduced fatty acid bioconversion activity along the n-3 and n-6 pathways, up to the production of 20:5n-3 and 20:4n-6, respectively. This suggests that the pathway exhibits a "funnel like" progression of activity rather than the existence of a single rate limiting step. The production of 22:5n-3 and 22:6n-3 was more active than that of 20:5n-3. However, despite this trend in reduced apparent in vivo net enzyme activity, the efficiency of the various bioconversion steps (measured as % of bioconverted substrate) confirmed an opposing trend. A 3.2-fold higher Δ-6 desaturase affinity towards 18:3n-3 over 18:2n-6 and an 8-fold greater Δ-5 desaturase affinity towards 20:4n-3 over 20:3n-6 were recorded. The main results of the study were that (1) rainbow trout are quite efficient at bioconverting 18:3n-3 to 22:6n-3, and (2) the LC-PUFA biosynthetic pathway is substrate limited. Fillet n-3 LC-PUFA concentrations increased with the increasing dietary supply of 18:3n-3. Despite an almost identical dietary supply of n-3 LC-PUFA, originating from the fish meal fraction of the diets, the fillets of trout fed the diet richest in 18:3n-3 were 2-fold higher in n-3 LC-PUFA than fish fed low 18:3n-3 diets. Nevertheless, fillets of trout fed a fish oil control diet contained more than double the amount of n-3 LC-PUFA compared to fish fed the diets richest in 18:3n-3. SN - 1558-9307 UR - https://www.unboundmedicine.com/medline/citation/21892784/LC_PUFA_biosynthesis_in_rainbow_trout_is_substrate_limited:_use_of_the_whole_body_fatty_acid_balance_method_and_different_18:3n_3/18:2n_6_ratios_ L2 - https://link.springer.com/article/10.1007/s11745-011-3607-4 DB - PRIME DP - Unbound Medicine ER -