Oxidative Phosphorylation-Dependent and -Independent Oxygen Consumption by Individual Preimplantation Mouse Embryos1

Abstract

The self-referencing electrode technique was employed to noninvasively measure gradients of dissolved oxygen in the medium immediately surrounding developing mouse embryos and, thereby, characterized changes in oxygen consumption and utilization during development. A gradient of depleted oxygen surrounded each embryo and could be detected >50 microm from the embryo. Blastocysts depleted the surrounding medium of 0.6+/-0.1 microM of oxygen, whereas early cleavage stage embryos depleted the medium of only 0.3+/-0.1 microM of oxygen, suggesting a twofold increase in oxygen consumption at the blastocyst stage. Mitochondrial oxidative phosphorylation (OXPHOS) accounted for 60-70% of the oxygen consumed by blastocysts, while it accounted for only 30% of the total oxygen consumed by cleavage-stage embryos. The amount of oxygen consumed by non-OXPHOS mechanisms remained relatively constant throughout preimplantation development. By contrast, the amount of oxygen consumed by OXPHOS in blastocysts is greater than that consumed by OXPHOS in cleavage-stage embryos. The amount of oxygen consumed by one-cell embryos was modulated by the absence of pyruvate from the culture medium. Treatment of one-cell embryos and blastocysts with diamide, an agent known to induce cell death in embryos, resulted in a decline in oxygen consumption, such that the medium surrounding dying embryos was not as depleted of oxygen as that surrounding untreated control embryos. Together these results validate the self-referencing electrode technique for analyzing oxygen consumption and utilization by preimplantation embryos and demonstrate that changes in oxygen consumption accompany important physiological events, such as development, response to medium metabolites, or cell death.

Impact of a long-term complex rehabilitation on chronic fatigue and cardiorespiratory parameters in patients with chronic heart failure

“…Ventiliaciniai ekvivalentai rodo ventiliacijos efektyvumą, tai yra kiek O 2 organizmas geba pasisavinti ir kiek CO 2 pašalina iš minutinės ventiliacijos oro tūrio (14,16). 20 a. septintojo ir aštuntojo dešimtmečio angliarūgštės biocheminiai tyrimai (13,15) parodė didelę jos svarbą medžiagų apykaitos reguliacijai ir biosintezei. Tyrimais įrodyta, kad pažeistų biologinių mikrostruktūrų atsikūrimui (energijos tiekimui, naujų baltymų, riebalų ir angliavandenių komponentų biologinei sintezei, Krebso ciklo greičiui) labai svarbus pakankamas anglies dioksido ir angliarūgštės kiekis audiniuose.…”

“…Todėl, esant lėtiniams ir nedideliems kvėpavimo sutrikimams, pCO 2 slėgis ir kraujo dujų rodmenys ne visada būna nukrypę nuo normos (16,17). Bet pacientas gali jausti energijos trūkumą ir nuovargį dėl CO 2 metabolizmo sutrikimo ląstelėje (13,15). Ląstelės apykaitoje CO 2 molekulė dalyvauja biosintezės reakcijose ir nuo CO 2 koncentracijos tiesiogiai priklauso jų greitis.…”

“…Koreliacinė analizė parodė, kad anglies dioksido apykaita susijusi su nuovargiu labiau nei deguonies. Remiantis teorinėmis prielaidomis (13,15), galima teigti, kad, esant didesniam anglies dioksido ir bikarbonatų kiekiui, greitėja baltymų (purino ir pirimidino bazių sintezė, ATF susidarymas), angliavandenių (pirovynuogių rūgšties karboksilinimas ir Krebso ciklo dikarboninių rūgščių susidarymas) ir riebalų (riebalų rūgščių sintezės pradžia -acetil KoA karboksilinimas) biosintezė, greitėja Krebso ciklas ir gerėja ląstelės aprūpinimas energija. Anglies dioksidas ir bikarbonatai taip pat yra pagrindinė organizmo buferinė sistema.…”

Nitric oxide modulates mitochondrial activity and apoptosis through protein S-nitrosylation for preimplantation embryo development

“…Although the "immature" mitochondria in mammalian fertilized eggs differ from the "mature" mitochondria in somatic cells, the "immature" mitochondria are also involved in the early phase of oxidative stress-induced apoptosis [23]. In mouse oocytes and embryos, constant levels of ATP are maintained by active mitochondrial oxidative phosphorylation [9,38].…”

Does serum cause lipid-droplet accumulation in bovine embryos produced in vitro, during developmental days 1 to 4?

“…Then, from 16 cells stage, the consumption of glucose increases and appears to be essential for further development [7,22]. Through the mitochondrial pathway glucose is metabolized giving a small contribution to the energy requirements in cleavage stage [58] increasing to the blastocyst stage [8]. However, it would be the pentose phosphate pathway which leads to the accumulation of lipids obtained by de novo lipidogenesis [9].…”