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Lipid metabolism during embryonic and early postembryonic development of Xenopus laevis
Insights
Lipid synthesis in Xenopus laevis embryos dramatically increases at the feeding stage, with phosphatidylcholine, phosphatidylethanolamine, and sterol esters doubling. Non-lipid reserves fuel this de novo lipid synthesis before feeding begins.
Area of Science:
- Developmental Biology
- Biochemistry
- Xenopus laevis Research
Background:
- Lipid metabolism is crucial for embryonic development.
- Understanding lipid dynamics during early development is essential for identifying growth requirements.
Purpose of the Study:
- To investigate changes in lipid content and synthesis during Xenopus laevis embryonic development.
- To determine the timing and sources of lipid accumulation before the feeding stage.
Main Methods:
- Analysis of major lipid classes (phosphatidylcholine, phosphatidylethanolamine, sterol esters) in Xenopus embryos.
- Incorporation studies using [14C]acetate to trace de novo lipid synthesis.
- Pulse-chase experiments to investigate lipid reserve mobilization.
Main Results:
- Major lipid amounts remained stable until after hatching.
- Phosphatidylcholine, phosphatidylethanolamine, and sterol esters doubled at the feeding stage.
- [14C]acetate incorporation shifted from fatty acyl chains to glycerol backbones and non-glycerol lipids post-hatching, indicating active synthesis.
Conclusions:
- Xenopus laevis embryos exhibit significant de novo lipid synthesis just before the onset of feeding.
- Mobilization of non-lipid reserves provides substrates for this lipid synthesis, supporting early development and transition to exogenous feeding.
Abstract:
Xenopus laevis embryos were analyzed for their lipid content from fertilization to feeding stage. The amounts of the major lipids did not change until after hatching, but at the feeding stage the amounts of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and sterol esters (SE) increased approximately twofold. Prior to hatching, [14C]acetate label was incorporated primarily into the fatty acyl chains of PE. After hatching, increasing amounts of label were found in other phospholipids, in their glycerol backbones, and in nonglycerol lipids. The most marked changes occurred just before the onset of feeding, and pulse-chase experiments suggest that nonlipid reserves are mobilized at this stage for de novo lipid synthesis.