The fatty acid desaturase 3 gene encodes for different FADS3 protein isoforms in mammalian tissues.

In 2000, Marquardt et al. (A. Marquardt, H. Stöhr, K. White, and B. H. F. Weber. 2000. cDNA cloning, genomic structure, and chromosomal localization of three members of the human fatty acid desaturase family. Genomics. 66: 176-183.) described the genomic structure of the fatty acid desaturase (FADS) cluster in humans. This cluster includes the FADS1 and FADS2 genes encoding, respectively, for the Delta 5- and Delta 6-desaturases involved in polyunsaturated fatty acid biosynthesis. A third gene, named FADS3, has recently been identified but no functional role has yet been attributed to the putative FADS3 protein. In this study, we investigated the FADS3 occurrence in rat tissues by using two specific polyclonal antibodies directed against the N-terminal and C-terminal ends of rat FADS3. Our results showed three potential protein isoforms of FADS3 (75 kDa, 51 kDa, and 37 kDa) present in a tissue-dependent manner. The occurrence of these FADS3 isoforms did not depend on the mRNA level determined by real-time PCR. In parallel, mouse tissues were also tested and showed the same three FADS3 isoforms but with a different tissue distribution. Finally, we reported the existence of FADS3 in human cells and tissues but different new isoforms were identified. To conclude, we showed in this study that FADS3 does exist under multiple protein isoforms depending on the mammalian tissues. These results will help further investigations to determine the physiological function of FADS3.

Intrauterine growth restriction modifies the developmental pattern of intestinal structure, transcriptomic profile, and bacterial colonization in neonatal pigs.

Neonates with intrauterine growth restriction (IUGR) are prone to suffer from digestive diseases. Using neonatal pigs with IUGR, we tested the hypothesis that IUGR may induce alterations in the developmental pattern of intestinal barrier and thereby may be responsible for IUGR-associated increased morbidity. Piglets with a birth weight near the mean birth weight (+/-0.5 SD) were identified as normal birth weight (control) and piglets with a mean -2 SD lower birth weight (-30%) were defined as piglets with IUGR. The developmental pattern of intestinal structure, transcriptomic profile, and bacterial colonization was investigated from birth to d 5 postnatal. At birth, intestinal weight and length, ileal and colonic weight per unit of length, and villous sizes were lower (P < 0.05) in piglets with IUGR than in same-age control piglets. These IUGR-induced intestinal alterations further persisted, although they were less marked at d 5. Counts of adherent bacteria to ileal and colonic mucosa were greater (P < 0.05) in 2-d-old piglets with IUGR than in same-age control piglets. Dynamic analyses of the transcriptomic profile of the intestine revealed molecular evidence of IUGR-induced intestinal growth impairment that may result from a change in the cell proliferation-apoptosis balance during the first days of life, while a protective process would occur later on. In addition, changes in the expression of several genes suggest a pivotal role of both glucocorticoids and microbiota in driving IUGR intestinal development during the neonatal period.

Deposition of dietary fatty acids, de novo synthesis and anatomical partitioning of fatty acids in finishing pigs.

Predicting aspects of pork quality becomes increasingly important from both a nutritional and technological point of view. The aim of the present study was to provide quantitative information on the relation between nutrient intake and whole-body fatty acid (FA) depositions. This information is essential to develop mechanistic models predicting the FA content of tissues. A serial slaughter study was carried out in which thirty pigs were slaughtered between 90 and 150 kg. The diet included 15 g/kg soyabean oil and contained 44 g/kg fat. Only 0.31 and 0.40 of the digested n-6 and n-3 FA were deposited, respectively. Approximately one-third of the n-3 supply that was deposited resulted from the conversion of 18:3 to other metabolites (i.e. EPA, docosapentaenoic acid and DHA). This proportion was affected by the pig genotype. De novo-synthesised FA represented 0.86 of the total non-essential FA deposition, and its average composition corresponded to 0.017, 0.286, 0.025, 0.217 and 0.454 for 14:0, 16:0, 16:1, 18:0 and 18:1, respectively. Although the average whole-body FA composition was relatively constant during the finishing period, this was not so for the tissues. In the carcass (without backfat), the content of 18:1 increased during the finishing period, whereas that of 16:0 and 18:0 decreased. Backfat captured a proportionally greater fraction of 18:2 than did the carcass of the residual tissues. In contrast, a proportionally greater fraction of the dietary 18:3 supply was deposited in the carcass compared to other tissues.

Deposition of dietary fatty acids and of de novo synthesised fatty acids in growing pigs: effects of high ambient temperature and feeding restriction.

Predicting aspects of pork quality becomes increasingly important from both a nutritional and a technological point of view. Little information is, however, available concerning the quantitative relation between nutrient intake and fatty acid (FA) deposition at the whole-animal level. In this study, eight blocks of five littermate barrows were used in a comparative slaughter trial. At 24 kg body weight (BW), one pig from each litter was slaughtered to determine the initial FA composition. The other littermates were assigned to one of four feeding levels (ranging from 70 % to 100 % of intake ad libitum) and were given a diet containing 0.36 g/kg lipid and 0.22 g/kg FA. The temperature for each block was maintained at either 23 or 30 degrees C. At 65 kg, the pigs were slaughtered and the body lipid and FA composition was determined. Seventy per cent of the digested n-6 FA and 50 % of the n-3 FA were deposited. The average composition of de novo synthesised FA corresponded to 1.7, 30.3, 2.4, 19.7 and 45.9 % for 14 : 0, 16 : 0, 16 : 1, 18 : 0 and 18 : 1 FA, respectively. At 23 degrees C and for feeding ad libitum, 33 % of 16 : 0 FA was deposited, 1.7 % shortened to 14 : 0, 63 % elongated to 18 : 0 and 2.8 % unsaturated to 16 : 1. Twenty-eight per cent of 18 : 0 FA was deposited and 72 % unsaturated to 18 : 1. At 30 degrees C, 18 : 0 FA desaturation was reduced by 3.5 %. Feed intake and temperature independently affected the elongation of 16 : 0 FA. A reduction in feed intake increased the elongation rate, whereas the increase in temperature reduced the elongation rate.