Changes in Energy Metabolism during the Early Development of &lt;i&gt;Xenopus laevis&lt;/i&gt;

Løvtrup-Rein, Huguette; Nelson, Lennart

doi:10.1159/000163142

Cited by 4 publications

(6 citation statements)

References 10 publications

(16 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…ranging from I 1 to 70 pU/pg [12,25]. The value of maximal activity of PDHc measured in the present work is about twentyfold higher than the value derived from the rate of decarboxylation of radioac tive exogenous pyruvate in Xenopus [2], Ac cording to several reports [2][3][4][5]26], glutamic acid, aspartate and alanine represent impor tant sources of energy for amphibian em bryos up to early gastrula. However, at later stages, as carbohydrates (mainly glycogen) become the predominant endogenous oxidizable substrate [1,[27][28][29], the mitochondrial production of reducing equivalents by the Krebs cycle should be increasingly dependent upon the formation of acetyl-CoA via PDHc.…”

Section: Thoman and Gerhartsupporting

confidence: 49%

“…The above calculations of Qmax/Qad hold only if glucose is completelyoxidized to COj and H^O. Since more than 80% of the glucose is known to be metabo lized through the pentose shunt during early development [2,4], a 5-6 times higher HK activity may be required than the one re vealed by oxygen consumptions.…”

Section: Discussionmentioning

confidence: 99%

“…Several studies on the energy metabolism of amphibian embryos have shown that the Embden-Meyerhof pathway, the Krebs cycle and the pentose shunt are functional from the first cleavage onwards, but their relative con tribution depends on the period of develop ment [1][2][3][4][5]. In the pregastrular stages the energy demand seems to be low and the met abolic processes are supplied mainly with en dogenous pools of nucleotide triphosphates (e.g.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Changes in Activity of the Regulatory Glycolytic Enzymes and of the Pyruvate-Dehydrogenase Complex during the Development of <i>Xenopus laevis</i>

Raddatz

Løvtrup-Rein²

1986

Pathobiology

View full text Add to dashboard Cite

In this study we investigated the variations of the maximal activities of the rate-controlling glycolytic enzymes (i.e., hexokinase, HK; phosphofructokinase, PFK; pyruvate kinase, PK) and of the pyruvate-dehydrogenase complex (PDHc) during the early embryogenesis of Xenopus laevis (from cleavage through hatching). All the enzymatic assays, using different coupled reactions, were performed spectrophotometrically on cytosolic and mitochondrial fractions. The maximal HK activity increases markedly from neurulation onwards, PFK activity presents a peak around gastrulation, PK activity remains relatively constant throughout the period studied and the highest PDHc activity is observed during cleavage. The specific activities display the same temporal pattern. Furthermore, in the sequence of reactions by which glucose is degraded to form acetyl-CoA, the maximal activities of PFK and PK are not limiting while those of HK and PDHc could be rate-limiting at relatively late developmental stages (hatching).

show abstract

Section: Thoman and Gerhartsupporting

confidence: 49%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Changes in Activity of the Regulatory Glycolytic Enzymes and of the Pyruvate-Dehydrogenase Complex during the Development of <i>Xenopus laevis</i>

Raddatz

Løvtrup-Rein²

1986

Pathobiology

View full text Add to dashboard Cite

show abstract

“…The changes in activity of GOT during development are in good agreement with the changes in respiration with glutamate as substrate (27) and in oxidation of glutamate in the whole embryo (30).…”

Section: Resultssupporting

confidence: 76%

Changes in Activity of Mitochondrial Enzymes during the Development of Xenopus laevis

Nelson

Løvtrup-Rein

1983

Dev Growth Differ

View full text Add to dashboard Cite

Changes in activity of mitochondrial enzymes were studied during the embryonic development of Xenopus laevis.The following enzymes were determined: malate dehydrogenase (MDH), isocitrate dehydrogenase (NAD+-dependent) (IDH), aspartate aminotransferase (GOT), cytochrome oxidase (COX), succinate dehydrogenase (SDH), rotenone-insensitive NADH cytochrome c reductase (NADH-red) and monoamine oxidase (MAO). IDH is constant throughout the period studied. COX and SDH, two enzymes of the inner membrane, are constant in pregastrula stages, and subsequently decrease significantly. MDH and NADH-red are highly active in the pregastrula stages and decline thereafter, while M A 0 is undetectable during early development and increases significantly only in the larvae. GOT increases during the cleavage stages, being most active in the gastrula stages, and decreases subsequently.The results are discussed in the sense of mitochondrial differentiation during the early development of the amphibian embryo.

show abstract

“…Between the first embryonic cleavage and gastrulation, embryos use amino acids from yolk in preference to carbohydrates from stored glycogen as the primary carbon source (18), with mitochondrial glutamate oxidation playing a major role (19,20). Glycolysis is not active during early embryonic cleavage even though the glycolytic machinery is intact (21)(22)(23).…”

Section: Discussionmentioning

confidence: 99%

Mitochondrial Gene Expression Is Regulated at the Level of Transcription during Early Embryogenesis of Xenopus laevis

Ammini

Hauswirth

1999

Journal of Biological Chemistry

View full text Add to dashboard Cite

Mitochondrial transcription in the early Xenopus laevis embryo resumes several hours before active mtDNA replication, effectively decoupling mtDNA transcription and replication. This developmental feature makes Xenopus embryogenesis an appealing model system to investigate the regulation of mitochondrial transcription. Studies reported here refine our understanding of the timing, magnitude, and mechanism of this transcriptional induction event. Northern analyses of six mitochondrial mRNAs (normalized to mtDNA) reveal that transcript levels remain basal between fertilization and gastrulation and then undergo a coordinate induction, culminating in a 20 -28-fold increase over egg levels by 48 h of development. Measurement of mitochondrial run-on transcription rates demonstrates a good correlation between transcription rates and transcript levels, showing that transcription itself is the primary determinant of transcript abundance. Experimental increases in mitochondrial ATP and energy charge also correlate with patterns of transcript levels and transcription rates, suggesting that developmental changes in the biochemical composition of the mitochondrial matrix could be regulating transcriptional activity. Consistent with this idea, transcriptional run-on rates in mitochondria of early embryos can be stimulated by the addition of tricarboxylic acid cycle intermediates to the run-on reaction. However, mitochondria of later stages do not show this response to the addition of metabolite. In combination, these data suggest that mitochondrial transcription is under metabolic regulation during early Xenopus embryogenesis.

show abstract

Changes in Energy Metabolism during the Early Development of <i>Xenopus laevis</i>

Cited by 4 publications

References 10 publications

Changes in Activity of the Regulatory Glycolytic Enzymes and of the Pyruvate-Dehydrogenase Complex during the Development of <i>Xenopus laevis</i>

Changes in Activity of the Regulatory Glycolytic Enzymes and of the Pyruvate-Dehydrogenase Complex during the Development of <i>Xenopus laevis</i>

Changes in Activity of Mitochondrial Enzymes during the Development of Xenopus laevis

Mitochondrial Gene Expression Is Regulated at the Level of Transcription during Early Embryogenesis of Xenopus laevis

Contact Info

Product

Resources

About