Molecular characterization of the level of sialic acids N-acetylneuraminic acid, N-glycolylneuraminic acid, and ketodeoxynonulosonic acid in porcine milk during lactation

Abstract

Sialic acids (Sia) are key monosaccharide constituents of sialylated glycoproteins (Sia-GP), human sialylated milk oligosaccharide (Sia-MOS), and gangliosides. Human milk sialylated glycoconjugates (Sia-GC) are bioactive compounds known to act as prebiotics and promote neurodevelopment, immune function, and gut maturation in newborns. Only limited data are available on the Sia content of porcine milk. The objective of this study was to quantitatively determine the total level of Sia N-acetylneuraminic acid (Neu5Ac), N-glycolylneuraminic acid (Neu5Gc), and ketodeoxynonulosonic acid (KDN) in porcine milk and to compare these levels in gilt and sow milk during lactation. Milk from 8 gilts and 22 sows was collected at 3 stages of lactation (colostrum, transition, and mature milk). Standard and experimental samples were derivatized using 1,2-diamino-4,5-methylenedioxy-benzene and analyzed by ultra-high-performance liquid chromatography using a fluorescence detector. The following new findings are reported: (1) Gilt and sow milk contained significant levels of total Sia, with the highest concentration in colostrum (1,238.5 mg/L), followed by transition milk (778.3 mg/L) and mature milk (347.2 mg/L); (2) during lactation, the majority of Sia was conjugated to Sia-GP (41-46%), followed by Sia-MOS (31-42%) and a smaller proportion in gangliosides (12-28%); (3) Neu5Ac was the major form of Sia (93-96%), followed by Neu5Gc (3-6%) and then KDN (1-2%), irrespective of milk fraction or stage of lactation; (4) the concentration of Sia in Sia-GP and Sia-MOS showed a significant decline during lactation, but the level of ganglioside Sia remained relatively constant; (5) mature gilt milk contained a significantly higher concentration of Sia-GP than sow milk. The high concentration of total Sia in porcine milk suggests that Sia-GC are important nutrients that contribute to the optimization of neurodevelopment, immune function, and growth and development in piglets. These findings provide an important rationale for the inclusion of Sia-GC in pig milk replacers to mimic porcine milk composition for the optimal growth and development of piglets.

Sequential One-Pot Multienzyme Chemoenzymatic Synthesis of Glycosphingolipid Glycans

“…40,41 Kdn-containing gangliosides have been found in the sperm, 42 ovarian fluid, 43 testis 44 of rainbow trouts as well as in yak milk 45 and possibly in porcine milk. 46 Neu5Ac8OMe has been found in starfish as the components of gangliosides 47,48 and human erythrocyte membrane. 49 Its unique property of resistance to sialidases makes the glycans containing Neu5Ac8OMe moiety interesting for biofunctional studies.…”

Characterization of porcine milk oligosaccharides over lactation between primiparous and multiparous female pigs

“…The details of milk sample collection from sow and gilts was the same as our published method 51 . Milk samples were collected from gilts and sows on colostrum at day 1, transitional milk at day 3 and mature milk at day 15 of lactation by manual expression during the same time period each morning (0900–1200 h).…”

Intestine specific regulation of pig cytidine-5′-monophospho-N-acetylneuraminic acid hydroxylase gene for N-glycolylneuraminic acid biosynthesis

“…Although CMAH gene expression is basically regulated by development-derived factors and pathogenic infectious environments, the molecular mechanism(s) underlying the regulation of the CMAH gene, particularly in the viewpoint of directly control of Neu5Gc biosynthesis, is still unclear in any organism. In a recent report describing Sia levels in porcine milk during lactation, Neu5Ac has been found to be the major form of Sia (93–96%) while Neu5Gc (3–6%) is a minor form based on their contents irrespective of milk lactation stage 26 . However, Neu5Gc was unexpectedly the major Sia form in the porcine spleen (67–79%) and lung (36–49%) based on their contents.…”