Abstract
A rapid series of synchronous cell divisions initiates embryogenesis in many animal species, including the frog Xenopus laevis. After many of these cleavage cycles, the nuclear to cytoplasmic ratio increases sufficiently to somehow cause cell cycles to elongate and become asynchronous at the mid-blastula transition (MBT). We have discovered that an unanticipated remodeling of core metabolic pathways occurs during the cleavage cycles and the MBT in X.laevis, as evidenced by widespread changes in metabolite abundance. While many of the changes in metabolite abundance were consistently observed, it was also evident that different female frogs laid eggs with different levels of at least some metabolites. Metabolite tracing with heavy isotopes demonstrated that alanine is consumed to generate energy for the early embryo. dATP pools were found to decline during the MBT and we have confirmed that maternal pools of dNTPs are functionally exhausted at the onset of the MBT. Our results support an alternative hypothesis that the cell cycle lengthening at the MBT is triggered not by a limiting maternal protein, as is usually proposed, but by a decline in dNTP pools brought about by the exponentially increasing demands of DNA synthesis.
Highlights
The metabolic pathways that route the traffic of small molecules through cells arose very early in evolution and have been strongly conserved
The deep conservation of metabolic pathways does not imply that all animal cells have the same metabolism
Following up on some of the most intriguing changes led to insights into energy metabolism in early embryos, as well as support for an alternative model of the cell cycle lengthening at the mid-blastula transition (MBT)
Summary
The metabolic pathways that route the traffic of small molecules through cells arose very early in evolution and have been strongly conserved. Following up on some of the most intriguing changes led to insights into energy metabolism in early embryos, as well as support for an alternative model of the cell cycle lengthening at the MBT.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.