An Evolutionary Perspective on Linoleic Acid Synthesis in Animals

Abstract

The diet of organisms generally provides a sufficient supply of energy and building materials for healthy growth and development, but should also contain essential nutrients. Species differ in their exogenous requirements, but it is not clear why some species are able to synthesize essential nutrients, while others are not. The unsaturated fatty acid, linoleic acid (LA; 18:2n-6) plays an important role in functions such as cell physiology, immunity, and reproduction, and is an essential nutrient in diverse organisms. LA is readily synthesized in bacteria, protozoa and plants, but it was long thought that all animals lacked the ability to synthesize LA de novo and thus required a dietary source of this fatty acid. Over the years, however, an increasing number of studies have shown active LA synthesis in animals, including insects, nematodes and pulmonates. Despite continued interest in LA metabolism, it has remained unclear why some organisms can synthesize LA while others cannot. Here, we review the mechanisms by which LA is synthesized and which biological functions LA supports in different organisms to answer the question why LA synthesis was lost and repeatedly gained during the evolution of distinct invertebrate groups. We propose several hypotheses and compile data from the available literature to identify which factors promote LA synthesis within a phylogenetic framework. We have not found a clear link between our proposed hypotheses and LA synthesis; therefore we suggest that LA synthesis may be facilitated through bifunctionality of desaturase enzymes or evolved through a combination of different selective pressures.Electronic supplementary materialThe online version of this article (doi:10.1007/s11692-017-9436-5) contains supplementary material, which is available to authorized users.

Effect of nucleotides supplementation to low‐fish meal feed on long‐chain polyunsaturated fatty acid composition of juvenile rainbow troutOncorhynchus mykiss

“…In the present study, among dietary nucleotides, dietary GMP, UMP and CMP significantly increased hepatic linoleic acid (LA, 18:2n-6) and α-linolenic acid (LNA, 18:3n-3) contents (Table 8). It has been known that most of the animals are not able to synthesize LA de novo from oleic acid (OA) and synthesis of LNA from LA due to lack of ∆12 (or ω6) and ∆15 (or ω3) desaturates, and thus required a dietary sources of those fatty acids (Malcicka, Visser, & Ellers, 2018;Venegas-Calerón, Sayanova, & Napier, 2010). Moreover, the fatty acid composition of liver and muscle in rainbow trout is well known to be influenced by the composition of dietary fatty acids (Caballero et al, 2002;Fonseca-Madrigal, Karalazos, Campbell, Bell, & Tocher, 2005).…”

Chemical composition, antioxidant, and antiproliferative activities of nine Chinese proso millet varieties

“…D and N8 had the highest linolenic acid (64.23%) and linolenic acid (2.51%) among all proso millet cultivars, respectively. Linolenic acid and linolenic acids are essential fatty acid and must be supplied via the diet (Kim, Nam, Kim, Hayes, & Lee, 2014;Malcicka, Visser, & Ellers, 2017). It is reported that linolenic acid has many benefits for human health, such as cardiovascular-protective, anti-cancer, neuroprotective, and anti-inflammatory effects (Kim et al, 2014).…”

Cloning and Functional Analysis of the FAD2 Gene Family from Desert Shrub Artemisia sphaerocephala

“…According to the location in the endoplasmic reticulum (ER) or plastids, Δ 12 FADs are divided into microsomal (FAD2) and plastid (FAD6) enzymes. In recent years, FAD2 genes have been identified and functionally analyzed in a variety of organisms, including plants, fungi, and some other lower animals [ 1,10]. To date, the FAD2 gene has been cloned from many plant species.…”