Fatty acid composition of lipids in immature cattle, pig and sheep oocytes with intact zona pellucida

Abstract

Cattle, pig and sheep oocytes isolated from healthy cumulus-oocyte complexes were pooled, within species, to provide samples of immature denuded oocytes with intact zona pellucida (n = 1000 per sample) for determination of fatty acid mass and composition in total lipid, constituent phospholipid and triglyceride. Acyl-containing lipid extracts, transmethylated in the presence of a reference penta-decaenoic acid (15:0), yielded fatty acid methyl esters which were analysed by gas chromatography. Mean (± SEM) fatty acid content in samples of pig oocytes (161 ± 18 µg per 1000 oocytes) was greater than that in cattle (63 ± 6 µg; P < 0.01) and sheep oocytes (89 ± 7 µg; P < 0.05). Of 24 fatty acids detected, palmitic (16:0; 25-35%, w/w), stearic (18:0; 14-16%) and oleic (18:1n-9; 22-26%) acids were most prominent in all three species. Saturated fatty acids (mean = 45-55%, w/w) were more abundant than mono-(27-34%) or polyunsaturates (11-21%). Fatty acids of the n-6 series, notably linoleic (18:2n-6; 5-8%, w/w) and arachidonic acid (20:4n-6; 1-3%), were the most abundant polyunsaturates. Phospholipid consistently accounted for a quarter of all fatty acids in the three species, but ruminant oocytes had a lower complement of polyunsaturates (14-19%, w/w) in this fraction than pig oocytes (34%, w/w) which, for example, had a three-to fourfold greater linoleic acid content. An estimated 74 ng of fatty acid was sequestered in the triglyceride fraction of individual pig oocytes compared with 23-25 ng in ruminant oocytes (P < 0.01). It is concluded that the greater fatty acid content of pig oocytes is primarily due to more abundant triglyceride reserves. Furthermore, this speciesspecific difference, and that in respect of polyunsaturated fatty acid reserves, may underlie the contrasting chilling, culture and cryopreservation sensitivities of embryos derived from pig and ruminant (cattle, sheep) oocytes.

The impact of obesity on egg quality

“…The lipid droplet protein, perlipin-2 was co-localized with these lipid droplets; and perlipin-2 mRNA increased after hCG administration in mice [67]. In some species such as cattle, sheep, and pigs lipid content is relatively high in the oocyte under normal conditions [68]. In follicular fluid of women the most abundant free fatty acids detected were oleic, palmitic, linoleic, and stearic acids; respectively [69].…”

Fat area and lipid droplet morphology of porcine oocytes during in vitro maturation with trans-10, cis-12 conjugated linoleic acid and forskolin

“…LD in porcine oocytes form a dark mass reaching almost all cytoplasm, but their function and importance are scarcely known. This dark appearance of porcine oocytes and embryos, compared with others species, has been attributed to an increased lipid -E-mail: rosalnp@gmail.com content (McEvoy et al, 2000;Genicot et al, 2005). On the other hand, the intermediate filaments of the cytoskeleton interact directly with these special organelles (Zehmer et al, 2009).…”

Antioxidants rescue stressed embryos at a rate comparable with co-culturing of embryos with human umbilical cord mesenchymal cells

“…These include enzymes such as superoxide dismutase, which generates hydrogen peroxide from superoxide radicals, and glutathione peroxidase and catalase, which convert hydrogen peroxide to water [5,6]. There are also low molecular weight antioxidants that function as ROS scavengers such as glutathione, vitamin C (ascorbic acid), alpha-tocopherols, and β-mercaptoethanol [7,8].…”