Respiration and Energy Metabolism

Yanagisawa, Tomio

doi:10.1007/978-3-642-65964-5_19

Cited by 12 publications

(5 citation statements)

References 196 publications

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“…This did not seem to affect the embryos adversely, in that the overall amount of O 2 consumption measured was 12.3 0.569 nmoles O 2 /1000 embryos/h (n = 9). This falls into the range of values of respiration by urchin embryos reported by other workers (Yanagisawa, 1975). The value for O 2 consumption was computed based on the slope of the curves over the first 1 5 minutes of an assay.…”

Section: Table IImentioning

confidence: 78%

THE ORGANIC MATRIX FROM OYSTER SHELL AS A REGULATOR OF CALCIFICATIONIN VIVO

Sikes¹,

Wheeler²

1986

The Biological Bulletin

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Exogenously supplied, C-14 labeled organic matrix from oyster shell inhibited spicule formation by embryos of the sea urchin, Arbacia punctulata, as measured by simultaneous incorporation of inorganic C-14. Analysis of isolated spicules showed that the matrix reached the site of crystal growth and became incorporated into crystals. Comparison of the amount of matrix in spicules to inhibitory levels for matrix in an in vitro, pH-stat crystallization assay showed that the matrix became incorporated into spicules in an amount sufficient to account for the observed in vivo inhibition. The matrix did not act as a general metabolic inhibitor, as measured by respirometry, but rather seemed to have only the specific effect on spicule formation. Calculated and measured values of natural levels of matrix in spicules and urchin tests matched reasonably well with experimentally determined levels that regulated the rate of crystallization in vivo. Overall, the results support the idea that matrix fulfills a direct, regulatory role in biomineralization.

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Section: Table IImentioning

confidence: 78%

THE ORGANIC MATRIX FROM OYSTER SHELL AS A REGULATOR OF CALCIFICATIONIN VIVO

Sikes¹,

Wheeler²

1986

The Biological Bulletin

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“…For reasons which are not clear, this class of molecules also appears to include the polypeptides specified by mtDNA, whose synthesis almost certainly contributes to the large increase in respiratory capacity seen over the time course of embryogenesis (31).…”

Section: Discussionmentioning

confidence: 99%

Mutually exclusive synthetic pathways for sea urchin mitochondrial rRNA and mRNA.

Elliott¹,

Jacobs²

1989

Mol. Cell. Biol.

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The structure and abundance of mitochondrial transcripts in sea urchin embryos were investigated by a combination of RNA blot-hybridization, SI mapping, and primer extension assays. Between the egg and blastula stages, the relative abundance of mitochondrial rRNAs declined slightly, while that of mitochondrial mRNAs increased up to 10-fold. Fine mapping of the termini of the rRNAs and of the adjacent transcripts indicated that, although they appeared to be butt-joined at their 5' ends to the upstream transcripts, tRNA-Phe 5' to the small subunit (12S) rRNA and NADH dehydrogenase subunit 2 mRNA 5' to the large subunit (16S) rRNA, respectively, their 3' ends were found to overlap the 5' ends of the downstream transcripts. 12S rRNA was found to extend 7 to 13 nucleotides into the sequence of tRNA-Glu; 16S rRNA was shown to terminate 3 to 5 nucleotides inside the coding region of cytochrome oxidase subunit I (COI) and 8 to 10 nucleotides from the mapped 5' end of COI mRNA. The rRNAs and the downstream transcripts must therefore be synthesized by distinct pathways, either by alternative processing of the same primary transcript(s) or by processing of different precursors. In either case, the events which select the ribosomal 3' ends preclude the production of functional transcripts of the downstream genes from the same precursor molecule. No developmental alterations in transcript structure were detected. We propose that mitochondrial RNA levels are regulated in early development by the selection of alternate and mutually exclusive RNA-processing pathways.Efficient protein synthesis in all cells and organelles depends on the maintenance of a large excess of rRNA over mRNA. In mammalian mitochondria, rRNA levels are up to 50 to 100 times those of individual mRNAs (2). This appears to be achieved by differential rates of synthesis of the two classes of transcript, with control exercised at the level of transcriptional termination (2, 9, 11, 13, 24). Transcription of the major coding strand of mammalian mitochondrial DNA (mtDNA) commences at the gene for tRNA-Phe (23, 24) just upstream of the effectively contiguous rRNA genes, which are separated only by tRNA-Val. Early termination of transcription at the 3' end of the large subunit (16S) rRNA gene results in the production of a subgenomic transcript which acts as a precursor to both rRNAs and probably to the two tRNAs. Relatively infrequent readthrough of this terminator is believed to result in the production of a genome-length transcript which is processed to the remaining mRNAs and tRNAs encoded on this strand.In sea urchins (Fig. 1) represented in the RNA populations of eggs and embryos (7,28), and at least one mRNA, encoding cytochrome oxidase subunit I (COI), accumulates during embryogenesis (28), whereas the level of the large subunit (16S) rRNA remains approximately constant. The ratio of mitochondrial mRNA to rRNA would therefore appear to be under developmental regulation.In order to gain insight into the mechanism by which this ratio is determined and modula...

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“…Many biological systems sustain more-or-less constant metabolic rates down to low O 2 concentrations (Yanigasawa, 1975;Palumbi and Johnson, 1982). For example, embryos of the sea urchin Arbacia have constant metabolic rates down to approximately 10%…”

Section: Model Developmentmentioning

confidence: 99%

Oxygen profiles in egg masses predicted from a diffusion–reaction model

Woods

Moran

2008

Journal of Experimental Biology

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SUMMARYWe developed a novel diffusion-reaction model to describe spatial and temporal changes in oxygen concentrations in gelatinous egg masses containing live, respiring embryos. We used the model in two ways. First, we constructed artificial egg masses of known metabolic density using embryos of the Antarctic sea urchin Sterechnius neumayeri, measured radial oxygen profiles at two temperatures, and compared our measurements to simulated radial oxygen profiles generated by the model. We parameterized the model by measuring the radius of the artificial masses, metabolic densities (=embryo metabolic rateϫembryo density) and oxygen diffusion coefficients at both ambient (-1.5°C) or slightly warmer (+1. 5

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Respiration and Energy Metabolism

Cited by 12 publications

References 196 publications

THE ORGANIC MATRIX FROM OYSTER SHELL AS A REGULATOR OF CALCIFICATIONIN VIVO

THE ORGANIC MATRIX FROM OYSTER SHELL AS A REGULATOR OF CALCIFICATIONIN VIVO

Mutually exclusive synthetic pathways for sea urchin mitochondrial rRNA and mRNA.

Oxygen profiles in egg masses predicted from a diffusion–reaction model

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