The effect of excess mevalonic acid on ubiquinone and tetrahymanol biosynthesis in Tetrahymena pyriformis.
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ABSTRACT:
SUBMITTER: Wilton DC
PROVIDER: S-EPMC1145090 | biostudies-other | 1985 Jul
REPOSITORIES: biostudies-other
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Project description:The biosynthesis of ubiquinone-8 from radioactive mevalonate by cultures of Tetrahymena pyriformis is demonstrated. Under normal conditions the incorporation of this radioactive precursor into ubiquinone and the triterpenoid alcohol tetrahymanol reflects the amounts of these two compounds in the cell. Growth of T. pyriformis in the presence of cholesterol results in a complete inhibition of incorporation of radioactive mevalonate into tetrahymanol while there is a corresponding increase of radioactive incorporation into ubiquinone. This increased incorporation of mevalonic acid into ubiquinone must reflect a reduced level of mevalonic acid in the cell under these conditions and is not due to increased ubiquinone biosynthesis, indicating tight regulation of the pathway prior to mevalonate formation.
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Project description:The behavior of ciliates has been studied for many years through environmental biology and the ethology of microorganisms, and recent hydrodynamic studies of microswimmers have greatly advanced our understanding of the behavioral dynamics at the single-cell level. However, the association between single-cell dynamics captured by microscopic observation and pattern dynamics obtained by macroscopic observation is not always obvious. Hence, to bridge the gap between the two, there is a need for experimental results on swarming dynamics at the mesoscopic scale. In this study, we investigated the spatial population dynamics of the ciliate, Tetrahymena pyriformis, based on quantitative data analysis. We combined the image processing of 3D micrographs and machine learning to obtain the positional data of individual cells of T. pyriformis and examined their statistical properties based on spatio-temporal data. According to the 3D spatial distribution of cells and their temporal evolution, cells accumulated both on the solid wall at the bottom surface and underneath the air-liquid interface at the top. Furthermore, we quantitatively clarified the difference in accumulation levels between the bulk and the interface by creating a simple behavioral model that incorporated quantitative accumulation coefficients in its solution. The accumulation coefficients can be compared under different conditions and between different species.
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Project description:1. Mitochondrial DNA from Tetrahymena pyriformis strain T has a buoyant density (rho) of 1.685 compared with rho1.688 for whole cell DNA. Mitochondrial preparations from T. pyriformis strain W show an enrichment of a light satellite (rho1.686), although this is not obtained free from nuclear DNA (rho1.692). 2. T. pyriformis mitochondrial DNA renatures rapidly and the kinetics of this process indicate a complexity of approx. 3x10(7) daltons. 3. The base-pairing in the renaturation product is of a precise nature, since the ;melting' temperature (80.5 degrees C) is indistinguishable from that of the native DNA (80.5 degrees C). 4. Centrifugation of mitochondrial DNA in an alkaline caesium chloride density gradient gives two bands, implying the separation of the complementary strands.
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Project description:The cytochrome c of Tetrahymena pyriformis GL (Phenoset A) had an isoelectric point of 6.5 and by sequence the following composition: Asp(7) Asn(2) Thr(4) Ser(8) Glu(6) Gln(2) Pro(7) Gly(13) Ala(13) Val(7) Met(2) Ile(5) Leu(6) Tyr(2) Phe(5) Lys(11) His(3) Trp(1) Arg(3) Cys(2) (total 109 residues). The peptides derived from the protein afforded complete overlap, so a complete sequence could be determined without reference of homologous proteins. Alignment with other mitochondrial cytochromes c required two internal deletions totalling three residues and an N-terminal region two residues longer than, and a C-terminal region one residue shorter than, the previously known limits. The sequence was the most divergent of the known mitochondrial cytochromes c, suggesting a distant relationship of ciliates to other eukaryotes. Details of the sequence data have been deposited as Supplementary Publication no. SUP 50068 (37 pages) at The British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7 BQ, U.K., from whom copies can be obtained on the terms given in Biochem. J. (1976) 153,5.
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Project description:A soluble dolichyl phosphate phosphatase from Tetrahymena pyriformis was purified about 68-fold. The enzyme appeared to be specific for dolichyl phosphate and existed in two interrelated forms, one of mol.wt. about 500000 and the other of mol.wt. about 63000. The enzyme was strongly inhibited by 5 mM-Mn2+ and was strongly stimulated by Mg2+. Tetrahymena in the exponential growth phase contained more of this enzymic activity than cells in stationary or lag phase. The dolichyl phosphate phosphatase may be loosely bound to mitochondrial membranes. Two roles proposed for this enzyme are (1) that of releasing dolichol from its phosphorylated biosynthetic form for its use in the cell as unesterified dolichol or dolichyl ester and/or (2) that of regulation of synthesis of glycoproteins or some other glycosylated compound.
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Project description:A method is described that enables a chromatin fraction containing ribosomal DNA (DNA containing sequences coding for rRNA) to be prepared from the macronuclei of growing or stationary cultures of Tetrahymena pyriformis. This material is obtained in yields of between 25 and 75% of the theoretical maximum. The DNA in this fraction was identified as ribosomal DNA on the basis of its density and molecular weight, and it appears not to be appreciably contaminated by other DNA. The method relies on the approximate assumption that ribosomal DNA is the smallest species of DNA in chromatin in the nucleus, and avoids the use of mechanical force, or enzyme action, to fractionate chromatin.
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