It was the purpose of this study to investigate the effect of various concentrations of IAA on the nucleic acids of Chlorella pyrenoidosa TX 7-11-05. The time during the life cycle when the greatest effect occurred was investigated by the use of synchronous cultures.

Ball State University LibrariesLibrary services and resources for knowledge buildingMasters ThesesThere is no abstract available for this thesis.

Ball State University LibrariesLibrary services and resources for knowledge buildingMasters ThesesThere is no abstract available for this thesis.

Synchronous cultures of a high temperature strain of Chlorella pyrenoidosa have been used to determine the activity of the TMP kinase during cellular development. It was observed that the apparent enzyme activity was closely correlated with the rate of DNA biosynthesis. During the period of nuclear division, when DNA synthesis is at its maximum apparent TMP kinase activity is highest. The maximum in enzyme activity, however, slightly precedes the peak in DNA synthesis. These results support the hypothesis that TMP kinase activity is a factor controlling the rate of DNA biosynthesis. It appeared that the dramatic shifts in the level of TMP kinase activity were a result of variations in the rate of enzyme synthesis rather than control of enzyme activity by small molecule inhibitors or activators. / Ph. D.

The factors which regulate enzyme activity in the growing cell have been the subject of active research during the past decade and are generally considered under the heading of "metabolic control". At least three control parameters must be considered as regulating the active level of a given enzyme: control of enzyme synthesis at the gene level, control of enzyme activity by small molecule metabolites once the enzyme has been synthesized, and control of enzyme activity imposed by its structural orientation within the cell and/or its organelles (which would affect permeability of substrates, cofactors, etc.). It can be hypothesized that periodism in the intracellular level of a given metabolite must be accompanied by periodism in the active level of one or more of the enzymes responsible for the synthesis or breakdown of this metabolite. Synchronized cultures of microorganisms afford a unique tool for studying periodic changes in the intracellular levels of metabolites during cell growth. The studies presented in this thesis were designed to elucidate the relationships between the activity of Aspartate Transcarbamylase and factors which affect and are affected by the activity of this enzyme in synchronized cultures of Chlorella pyrenoidosa. Aspartate Transcarbamylase, the first enzyme in pyrimidine biosynthesis, has been reported to be controlled by a phenomenon known as " product-inhibition". This enzyme was located in the soluble supernatant of a 100,000 x g preparation of sonicated C. pyrenoidosa ceils. The pH optimum (9.2), temperature optimum (approx. 37°), and stability characteristics of this enzyme from this organism are reported. Aspartate Transcarbamylase when measured during two consecutive synchronous growth cycles in C. pyrenoidosa under continuous illumination was found to increase at alternating exponential rates in each growth cycle. When the increase in Aspartate Transcarbamylase was expressed in its logarithmic form, a plot with linear segments was obtained, each segment having a different slope. The rate of increase of Aspartate Transcarbamylase activity during early daughter cell development changes (increases) at the 5th h. The 5th through 9th h of cell growth, where Aspartate Transcarbamylase activity is increasing at an accelerated rate, corresponds to the premitotic and nuclear division stages in the cell. Correlated with this period of increased Aspartate Transcarbamylase activity (5th through 9th h) there is an increase in the rate of accumulation of RNA and DNA concurrent with increase in the rate of accumulation of intermediates in the acid-soluble, Norit-A adsorbable-P pool (which contains the nucleotide-P fraction). At. approximately the 9th h of cell growth there is a decrease in the rate of increase of Aspartate Transcarbamylase activity. Evidence is presented indicating that the depression of activity during this period is at least partly due to the presence of Norit-A adsorbable compound(s) present in the cell (pyrimidine nucleotides, the principal inhibitors of this enzyme, would be Norit-A adsorbable). At the 8th h of cell growth ( 1h prior to the period of depressed Aspartate Transcarbamylase activity) the acid-soluble, Norit-A adsorbable-P pool reaches a maximum value (as % of total cellular-P). These data together with inhibition studies with a variety of nucleoside mono-, di-, and tri-phosphates suggest that pyrimidine nucleotides may be factors regulating Aspartate Transcarbamylase activity during cellular development. / Ph. D.

M.S.

Live green microalgae Chlorella pyrenoidosa was introduced in the anode of microbial fuel cell (MFC) to act as an electron donor. The electrogenic capability of algae Chlorella pyrenoidosa was investigated in two models of algal microbial fuel cells (MFCs) constructed with carbon electrodes and no mediator. The mechanism was studied by results of ATP inhibitor (Resveratrol) and protonophore (2, 4-dinitrophenol), which supporting the important role of mitochondria in electricity generation. The results of different light intensity and algae concentration indicate that low concentration of 106 (OD680nm) and low light intensity (2500 Lux) generated higher electricity. In the oxygen controlled study, it was found that oxygen generated by algae in anode was a limiting factor for electricity generation. Electricity generation was observed in two chamber algae MFC lasting at least for 24 hours. Results might provide a platform for the development of self-sustainable algal culturing microbial fuel cell (MFC). Electricity was found to increase in response to 4-nitrophenol (4NP) and 4-nitroanaline (4NA) for both measurements of current and open circle voltage (OCV). The positive response of algae to 4NP in increasing the 4NP production and electricity generation in MFC proposed the possible application in the detection of E.coli, as 4NP is involved in the intermediate step of the detection process. Results indicate Algae MFC was suitable for the detection of E. coli. of concentration higher than 106 using OCV measurement. Keywords: Electricity generation, Chlorella pyrenoidosa, Microbial fuel cell.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第22849号 / 農博第2432号 / 新制||農||1082(附属図書館) / 学位論文||R2||N5309(農学部図書室) / 京都大学大学院農学研究科応用生物科学専攻 / (主査)教授 佐藤 健司, 教授 澤山 茂樹, 教授 菅原 達也 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM