title: Does the respiratory rate in sea urchin embryos increase during early development without proliferation of mitochondria?
abstract: During early development of the sea urchin, the respiratory rate, enhanced upon fertilization, is maintained up to hatching (pre-hatching period) and then gradually increases to a maximum at the gastrula stage (post-gastrula period). Except for a short duration after fertilization, respiration in embryos is strongly inhibited by CN- and antimycin A. During the whole span of early development, the amounts of proteins, cytochromes and the specific activities of cytochrome c oxidase and reduced nicotinamide adenine dinucleotide (NADH) cytochrome c reductase in mitochondria are practically the same as in unfertilized eggs. A marked augmentation of mitochondrial respiration after hatching probably occurs without net increase in whole mitochondrial intrinsic capacities. Carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP) or tetramethyl p-phenylenediamine (TMPD) enhances the respiratory rate in the pre-hatching period but hardly augments the respiration in the post-gastrula period. In the presence of both FCCP and TMPD, the respiratory rate in the pre-hatching period was as high as in the post-gastrula period. Probably, electron transport in the mitochondrial respiratory chain is regulated by acceptor control and limitation of cytochrome c reduction in the pre-hatching period and released from those regulations in the post-gastrula period. Acceptor control of respiration is experimentally reproduced in isolated mitochondria by making adenine nucleotide levels as those levels in the pre-hatching period.
authors.affiliation: Department of Biology, School of Education, Waseda University, Shinjuku-ku, Tokyo, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Fujiwara
authors.forename: I
authors.initials: I
authors.lastname: Yasumasu
mesh_terms: D000818:Animals; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D002499:Centrifugation, Density Gradient; D002701:Chloramphenicol / Q000494:pharmacology; D003486:Cyanides / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000378:metabolism; D007202:Indicators and Reagents / Q000494:pharmacology; D008928:Mitochondria / Q000201:enzymology / Q000502:physiology*; D009245:NADH Dehydrogenase / Q000378:metabolism; D009840:Oligomycins / Q000494:pharmacology; D010101:Oxygen Consumption; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012617:Sea Urchins / Q000196:embryology*; D013384:Succinate Cytochrome c Oxidoreductase / Q000378:metabolism; D013772:Tetramethylphenylenediamine / Q000494:pharmacology; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D003486:Cyanides; D007202:Indicators and Reagents; D009840:Oligomycins; D011500:Protein Synthesis Inhibitors; D014475:Uncoupling Agents; D003609:Dactinomycin; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D002701:Chloramphenicol; D003513:Cycloheximide; D013384:Succinate Cytochrome c Oxidoreductase; D009245:NADH Dehydrogenase; D003576:Electron Transport Complex IV; D013772:Tetramethylphenylenediamine