Preferential labeling of phosphatidylcholine during phospholipid synthesis by bovine mammary tissue

Abstract

Bovine mammary cells and tissue synthesize de novo the classes of phospholipids, found in mammary tissue and milk, from various precursor molecules. Several short term experiments were carried out in vitro, using labeled precursors, i.e., 1‐14C‐fatty acids; 2‐14C‐acetate; U‐14C‐glycerol; 1,2‐14C‐choline; 1,2‐14C‐ethanolamine; 2‐14C‐serine; and Me‐14C‐methionine. All the phospholipid classes were labeled. The specific activity of tissue phosphatidylcholine was consistently three to six‐fold greater than that of phosphatidylethanolamine. The results indicated that stepwise methylation of phosphatidylethanolamine with labeled methyl group of methionine was occurring to a minor extent, as was a negligible amount of choline exchange. Serine was incorporated into phosphatidylserine and sphingomyelin. Significant quantities of labeled phosphatidylserine were decarboxylated to phosphatidylethanolamine. Apparently phosphatidylcholine was synthesized de novo from choline via phosphorylcholine and CDP‐choline. Based on the present observations and other data, it is suggested that there may be two pools of phosphatidylcholine in lactating mammary cells.

A Novel Dynamic Impact Approach (DIA) for Functional Analysis of Time-Course Omics Studies: Validation Using the Bovine Mammary Transcriptome

“…Other top GO Biological process terms uncovered by the DIA also confirmed previous data. The production of phospholipids in bovine mammary during lactation is known to be high and indispensable for the synthesis of the fat globule membrane [39]. This finding supports the high impact of GO ‘Phosphatidylcholine biosynthesis process’ term (Figure 6).…”

The relationship between size and lipid composition of the bovine milk fat globule is modulated by lactation stage

“…In dairy farm animals like goats and cows, lactation stage is closely associated with energy balance, which is reflected in a higher concentration of long-chain fatty acids in milk produced in early compared with late lactation (Griinari, McGuire, Dwyer, Bauman, & Palmquist, 1997;Kinsella, 1973;Kinsella & McCarthy, 1968;Carriquiry et al, 2009;Duchacek, Vacek, Stadnik, Beran, & Okrouhla, 2012;Strzalkowska et al, 2009). Lactation stage was also shown to associate with decreased polar lipid concentration and altered composition (Bitman & Wood, 1990;Zou et al, 2012), and increased mean MFG diameter and decreased size distribution between mature and transition milk (Zou et al, 2012).…”

Comparative mammalian choline metabolism with emphasis on the high-yielding dairy cow

“…Following labelled choline infusion this was not recovered in the milk Met pool, but the contribution of choline to milk fat was ten times greater than that of Met. We can conclude therefore that, while Met may stimulate milk and milk fat production by enhancing lipoprotein synthesis, gluconeogenesis, and providing methyl groups for phospholipid synthesis in the liver, choline is required for the de novo synthesis of phospholipids in the mammary gland and to spare Met as a methyl donor (Kinsella, 1973;Emmanuel & Kennelly, 1984;Huber et al 1984). Lobley et al (1996) used radiolabelled Met to investigate the importance of transmethylation reactions in sheep infused with choline and creatine.…”