Metabolic fate of yolk fatty acids in the developing king penguin embryo

Rapid embryonic accretion of docosahexaenoic acid (DHA) in the brain of an altricial bird with an aquatic-based maternal diet

Docosahexaenoic acid (DHA) is an important and abundant fatty acid moiety in vertebrate brains. We measured brain phospholipid composition during development in red-winged blackbirds (Agelaius phoeniceus), an altricial species that breeds in aquatic habitats. We also manipulated diet by feeding nestlings fish oil or sunflower oil. Finally, we assessed selective uptake of yolk by comparing the yolk fatty acid composition of freshly laid eggs and day-old hatchlings. Relative to other altricial species, blackbirds achieved high DHA in brain phospholipids (20% of phospholipid fatty acids in day-old hatchlings). This was not a result of selective uptake from the yolk, but rather a consequence of a high proportion of DHA in the yolk (2.5% of total lipids) at laying. Our dietary study confirmed that nestling brains are sensitive to fatty acid supply. Red-winged blackbirds may be able to advance cognitive development relative to other altricial species due to their aquatic maternal diet.

Zebrafish lipid droplets regulate embryonic ATP homeostasis to power early development

In zebrafish embryos, the maternally supplied pool of ATP is insufficient to power even the earliest of developmental events (0-3 hpf) such as oocyte-to-embryo transition (OET). The embryos generate an additional pulse (2.5 h long) of ATP (1.25-4 hpf) to achieve the embryonic ATP homeostasis. We demonstrate that the additional pulse of ATP is needed for successful execution of OET. The maternally supplied yolk lipids play a crucial role in maintaining the embryonic ATP homeostasis. In this paper, we identify the source and trafficking routes of free fatty acids (FFAs) that feed the mitochondria for synthesis of ATP. Interestingly, neither the maternally supplied pool of yolk-FFA nor the yolk-FACoA (fatty acyl coenzyme A) is used for ATP homeostasis during 0-5 hpf in zebrafish embryos. With the help of lipidomics, we explore the link between lipid droplet (LD)-mediated lipolysis and ATP homeostasis in zebrafish embryos. Until 5 hpf, the embryonic LDs undergo extensive lipolysis that generates FFAs. We demonstrate that these newly synthesized FFAs from LDs are involved in the maintenance of embryonic ATP homeostasis, rather than the FFAs/FACoA present in the yolk. Thus, the LDs are vital embryonic organelles that maintain the ATP homeostasis during early developmental stages (0-5 hpf) in zebrafish embryos. Our study highlights the important roles carried on by the LDs during the early development of the zebrafish embryos.

A comparative assessment of fatty acids in Antarctic organisms from the Ross Sea: Occurrence and distribution

Lipids are important energy source and structural component for cellular membranes and tissues, involved in the osmoregulation and immune response, and are very important in the bioaccumulation of lipophilic chemicals too. Among lipids, fatty acids (FAs) give information on diet of organisms, since FA of consumer lipids can be related to those of diet; plants and animals vary in their FA signature because of differences in the synthesis of lipids. In this study, lipid content and FA composition in tissues of Antarctic organisms from the Ross Sea (Odontaster validus, Sterechinus neumayeri, Chionodraco hamatus, Trematomus bernacchii, Pygoscelis adèliae) were assessed. Differences in lipid characterisation were found between both species and tissues. The lipid content was highest in C. hamatus liver (3.51%), and lowest in T. bernacchii muscle (0.16%). The polyunsaturated fatty acids (PUFAs) prevailed in the C. hamatus muscle, and among FAs, the docosahexaenoic acid (DHA; C22:6n3) was the most abundant (20.93%). The C22:6n3 accumulated more in fish and penguin tissues than in invertebrate species. The high contribution of unsaturated fatty acids (>74%) in fish tissues wats related to the low environmental temperature. The fatty acid profile and the essential fatty acids occurrence were also discussed in the light of physiological adaptations and feeding habits of organisms; the relationships with contaminant bioaccumulation were also assessed. To the best of our knowledge, this is the first report of fatty acid composition and fingerprint in a Ross Sea trophic web and their correlation with contaminant concentration.

The role of mitochondrial function in the oocyte and embryo

Mitochondria have long been known to be the powerhouses of the cell but they also contribute to redox and Ca2+ homeostasis, provide intermediary metabolites and store proapoptotic factors. Mitochondria have a unique behavior during development. They are maternally transmitted with little (if any) paternal contribution, and they originate from a restricted founder population, which is amplified during oogenesis. Then, having established the full complement of mitochondria in the fully grown oocyte, there is no further increase of the mitochondrial population during early development. The localization of mitochondria in the egg during maturation and their segregation to blastomeres in the cleaving embryo are strictly regulated. Gradients in the distribution of mitochondria present in the egg have the potential to give rise to blastomeres receiving different numbers of mitochondria. Such maternally inherited differences in mitochondrial distribution are thought to play roles in defining the long-term viability of the blastomere in some cases and embryonic axes and patterning in others. Mitochondria may also regulate development by a number of other means, including modulating Ca2+ signaling, and the production of ATP, reactive oxygen species, and intermediary metabolites. If the participation of mitochondria in the regulation of sperm-triggered Ca2+ oscillations is now well established, the role of other properties of mitochondrial function during development remain largely unexplored probably due to the difficulty of accessing the mitochondrial compartment in an embryo. Maintaining a functional complement of maternally derived mitochondria is vital for the early embryo. Mitochondrial dysfunction may not only compromise developmental processes but also trigger apoptosis in the embryo. This dual role for mitochondria (to maintain life or to commit to cell death) may well represent a quality control system in the early embryo that will determine whether the embryo proceeds further into development or is quickly eliminated.

Developmental dynamics of some blood biochemical parameters in the growing turkey (Meleagris gallopavo)

Blood serum clinical biochemical parameters of fasted BUT Big 8 male turkeys were determined at the ages of 3 days, 4, 8, 12, 16 and 20 weeks, for a follow-up of the developmental changes of some serum metabolites, enzymes and ions. The serum protein content (total protein, albumin, globulin) increased with age, indicating also the moulting-associated metabolic changes in the age interval from the 8th to the 12th weeks. Creatinine was shown to have a peak at 3 days of age (role of muscle activity in thermogenesis), while urate concentration sensitively reflected the dietary protein amount. Serum triglycerides peaked at the time of yolk catabolism, while cholesterol was shown to indicate the moulting, as was serum malondialdehyde. Serum sodium content increased throughout the study. Alanine aminotransferase and aspartate aminotransferase activities increased along the ontogeny, while alkaline phosphatase activity decreased in parallel with the growth. Serum creatine kinase activity showed an over one-magnitude increase. General metabolic and enzymatic alterations were characteristic and applicable for the description of the ontogenetic development of a precocial (post-hatch triglyceride peak), large bodied, meat-type (lactate dehydrogenase, continuously increasing creatine kinase) bird species.