Isocitritase, Glycine-Alanine Transaminase, and Development in Blastocladiella Emersonii

1962

SUMMARYImproved methods are described for growing about lo8 to lo9 synchronized single generations of ordinary-colourless (OC) cells of the aquatic fungus Blastocladiella emersonii in submerged liquid 1200 ml. cultures at 24' . The stimulatory effect of white light on the synthesis of the internal pool of soluble protein and soluble polysaccharide, and on the dry wt./cell during ontogeny was assessed. Soluble protein was characterized by fractionation on DEAE-cellulose into a number of components : the quantities/cell were affected differentially by illumination. Light caused a sharp decrease in total glucose-6-phosphate dehydrogenase activity/cell during the last stages of growth, when the light-induced formation of soluble polysaccharide/cell was most pronounced.

mentioning

confidence: 99%

Light-Stimulated Polysaccharide and Protein Synthesis by Synchronized, Single Generations of Blastocladiella emersonii

Goldstein

1962

“…It is particularly noteworthy that during the development of an RS plant, bicarbonate also induces, simultaneously, an immediate exponential synthesis of isocitritase, a crucial enzyme required for removal of the isocitrate following its formation from a-ketoglutarate via isocitric dehydrogenase. This does not occur in the absence of bicarbonate during the early stages of development in an ordinary colourless (OC) plant (McCurdy & Cantino, 1960;Cantino, 1961). …”

Section: Discussionmentioning

confidence: 99%

Reversible Bicarbonate-Induced Enzyme Activity and the Point of no Return during Morphogenesis in Blastocladiella

Lovett

1961

SUMMARYWith synchronous single-generation cultures of the non-filamentous water fungus Blastocladiella emersonii the activities of isocitric dehydrogenase, a-ketoglutaric dehydrogenase, and cytochrome oxidase were studied during morphogenesis. The total isocitric dehydrogenase activity per plant increased rapidly following germination of the spore and reached its peak at the point of no return in ontogeny; this increase was about seven times greater than the increase in total cc-ketoglutaric dehydrogenase activity. During growth from the spore stage to the stage of irreversibility, the specific activity of isocitric dehydrogenase increased 850 yo while that of a-ketoglutaric dehydrogenase decreased 50 yo. By removing the external bicarbonate before the point of no return was reached, and thus reversing the morphogenetic pathway, the specific activity of isocitric dehydrogenase, which was in the process of increasing, decreased immediately, while the a-ketoglutaric dehydrogenase activity, which had decreased sharply, increased quickly once again, Similarly, the total activity of isocitric dehydrogenase per plant decreased precipitously while, without reversal, it continued to rise. Conversely, reversal of the morphogenetic path caused an immediate rise in the total a-ketoglutaric dehydrogenase activity per plant while, in the absence of reversal, enzyme activity remained on a level plateau, Thus, removal of bicarbonate induced a new morphogenetic path and, simultaneously, a 250% increase in the activity of one key enzyme and a 35 yo decrease in the activity of a second; on the other hand, the total protein and total activity of two other ' control ' enzymes (glucose-6-phosphate dehydrogenase and cytochrome oxidase) remained essentially constant, In contrast to the above, removal of bicarbonate immediately after the point of no return in morphogenesis had no significant effect on these same enzymes. The data provide substantial evidence that a reversible bicarbonate-induced enzyme synthesis is involved in morphogenesis ; i.e. in the mechanism of the bicarbonate-induced formation of resistant-sporangial plants in Blastocladiella.

“…A s soon as discharge of spores began irz situ (the exact time depending upon temperature and population density; see Results), plates were flooded with distilled water to accelerate spore liberation (for general procedures and discussion, see McCurdy & Cantino, 1960;Cantino & Lovett, 1968). Such suspensions of swimming spores were either used directly for light microscopy or centrifuged for electron microscopy, for which exceptionally dense spore populations were needed and obtained as follows: a Petri plate of mature plants was flooded with about 20 d. of water; the spore suspension thus obtained was used to flood a second plate of BlastocZudieZZa emersmii; the new spore suspension, now much denser, was used to flood a third plate of the fungus, and so on until an adequate concentration was obtained.…”

Section: Preparation Of Sporesmentioning

confidence: 99%

The Single Mitochondrion, Fine Structure, and Germination of the Spore of Blastocladiella emersonii

Lovett

Leak

et al. 1963

SUMMARYThe motile spore of the water fungus, BlatocladkZZu emersmii, contains a single, large, posterior, eccentrically disposed mitochondrion; some 6-12 prominent, strongly osmiophilic, lipid-like organelles, bordered by a double membrane, occur along its outer edge. A single flagellum with the classical 9-plus-2 fibrillar structure is attached by at least one banded rootlet to the mitochondrion. The nuclear cap (a package of ribosomes) overlies the nucleus and is separated from it by a double membrane. The cytoplasm is somewhat granular, contains structures believed to be organelles (previously described as y particles), but is devoid of any obvious cytoplasmic reticulum. Before spore germination, the flagellum undergoes a series of characteristic movements. Following this, the nuclear apparatus rotates through some 270°, but the spore itself does not turn. The flagellum is then retracted into the cell. Subsequently, the spore germinates by formation of a germ tube and the nuclear cap disintegrates.