Colorless Alga Research Articles

Prototheca filamenta: A fungus not an alga

The genusPrototheca is composed of colorless algae. Plastids, a characteristic feature of colorless algae, are absent fromP. filamenta cells. The growth pattern seen with light and scanning electron microscopes, and the ultrastructure observed with the transmission electron microscope suggest thatP. filamenta is a fungus. Consequently we recommend the removal ofP. filamenta from the genusPrototheca and subsequent investigation of this organism to determine its correct taxonomic placement among the fungi.

The properties and subcellular localization of acid phosphatases in the colourless alga, Polytomella caeca.

ABSTRACT The acid p-nitrophenyl phosphatase of homogenates of Polytomella caeca is a latent acid hydrolase, which is partially inhibited by NaF. Its distribution profile in density gradients (which is similar to that of naphthyl AS-TR phosphatase) suggests that this enzyme is partially lysosomal in location. Cytochemical evidence for the localization of acid phosphatases in fine subcellular structures is presented. Naphthyl AS-TR phosphatase is localized in vacuoles, points of focal degradation, Golgi bodies and dispersed throughout the cytosol. β-Glycero- phosphatase is confined to large vacuoles and the cytosol. The nature of acid phosphatase- containing organelles in P. caeca is discussed in view of the inability to detect eleven other latent acid hydrolases in cell-free homogenates.

Characterization of cytoplasmic and nuclear genomes in the colorless alga Polytoma. IV. Heterogeneity and complexity of the nuclear genome.

DNA isolated from purified nuclei of Polytoma obtusum has a buoyant density of 1.711 g/ml in CsCl, a Tm of 91.3° C in SSC, and a G + C content of 52.5% as determined by base composition analysis. Thermal dissociation and reassociation studies indicated that this nuclear DNA contains a considerable amount of heterogeneity. Under appropriate reannealing conditions for denatured DNA, about 15% of the DNA reannealed to form a satellite peak at a density of 1.711 g/ml within one hour. Native DNA fractions of different average buoyant densities, ranging from 1.723 to 1.708 g/ml were also obtained in a preparative CsCl gradient, indicating the presence of intermolecular heterogeneity at a molecular size of 8.5×106 daltons. The nuclear DNA reassociated as three distinct classes. The very fast species constituted about 20 % of the total hyperchromicity, the class of intermediate rate comprised roughly 10% of the nuclear DNA, while the remaining 70% consisted of unique sequences. The haploid genome set was estimated by renaturation kinetics studies to contain 5.0×1010 daltons of DNA or 7.5×107 nucleotide pairs. The analytical complexity of the total nuclear genome was found to be 9.35×1010 daltons, thus indicating that vegetative cells of P. obtusum are diploid.

Effect of growth rate on the macromolecular composition of Prototheca zopfii, a colorless alga which divides by multiple fission.

Prototheca zopfii, a eukaryote that divides by multiple fission, was investigated to determine how growth rate controls daughter cell number. The macromolecular composition, cell size, and number of nuclei per cell were determined in cultures during balanced growth in various media. Cellular mass, ribonucleic acid (RNA), deoxyribonucleic acid (DNA), carbohydrate, and nuclear number increased as positive linear functions of growth rate, whereas nuclear ploidy remained constant with a value of 0.098 pg of DNA/nucleus. The ratios of RNA to protein, protein to mass, and carbohydrate to mass were unaffected by growth rate, whereas the ratios of DNA to protein and RNA to DNA could be expressed as curvilinear functions of growth rate, the former negative and the latter positive. The dependency of normalized gene dosage (DNA/protein) on growth rate appeared as a distinguishing feature of multiple fission. Determination of the normalized rates of protein and RNA synthesis revealed that both increase linearly with growth rate. It is concluded that Prototheca zopfii may exist in a number of physiological states which are characterized by a unique size and macromolecular composition and which are dictated by growth rate.

Subcellular Fractionation of the Colourless Alga Polytomella caeca by Differential and Zonal Centrifugation

SUMMARY: Homogenates from Polytomella caeca were fractionated by differential centrifugation. All the mitochondria (located by measurement of cytochrome c oxidase) and most of the peroxisomes (located by measurement of catalase) sedimented at 105 g min. Most of the NADPH-cytochrome c oxidoreductase, IDPase and acid p-nitrophenyl phosphatase were still present in the supernatant. This supernatant also contained a cytochrome b, cytochromes P-450 and P-416. Zonal centrifugation indicated that catalase and cytochrome oxidase were entirely sedimentable at 6 × 106 g min and that NADPH- and antimycin A-insensitive NADH-cytochrome c oxidoreductases were not mitochondrial. Peroxisomes (ρ = 1.25) were separated from mitochondria (ρ = 1.20) by both rate and isopycnic-zonal centrifugation. Two zones of acid p-nitrophenyl phosphatase activity were detected, one at ρ = 1.15 and the other at ρ = 1.21, but no other acid hydrolases were found. Separation, of polysomes and various microsomal enzymes (IDPase, acid p-nitrophenyl phosphatase, NADH- and NADPH-cytochrome c oxidoreductases) was also achieved.

Infections Caused by Achloric Algae (Protothecosis)

Species of colorless algae of the genus<i>Prototheca</i>are recently being recognized as pathogens. Five human cases have been identified, three of them not previously reported. Algae are capable of growing in the skin, subcutaneous tissue, bursal sacs, and lymph nodes of man. Immunologic impairment was demonstrable in only one of the five patients.

Characterization of DNA components from some colorless algae

The DNA components of five colorless algae were characterized by their buoyant densities in cesium chloride. Two DNA components were detected in Polytoma obtusum and Polytoma uvella. Upon renaturation of the thermally denatured DNA the minor and approx. 15% of the major DNA component returned to their native densities. The buoyant densities of the major and minor DNA of P. obtusum and P. uvella are different from that of the morphologically and biochemically similar green alga Chlamydomonas reinhardtii. A major and a minor DNA component with the same buoyant densities as that of the green alga Euglena were also found in Astasia longa, which is morphologically similar to Euglena. The renaturation of the minor but not the major component was readily detectable by the change in buoyant density. Only one DNA component was detected in Polytomella agilis and Polytomella caeca. After thermal denaturation approx. 5% of each of these DNA components were renatured readily. Based on these data, the possible evolutionary origin of these colorless algae is discussed.

Fermentation of glucose by Chlorella.

1. It was confirmed that the colourless alga, Prototheca zopfii converts glucose completely to lactic acid during fermentation. 2. Lactic acid was the only acidic product of glucose fermentation by Chlorella strain 211/1e, 1.4 moles being formed for each mole glucose fermented. This strain produced negligible carbon dioxide and hydrogen; other fermentation products were not identified. 3. In regard to capacity for fermenting glucose, the Chlorella strains examined fell into 4 groups, namely (a) those producing about 0.75 moles lactic acid/mole glucose (strains 8b, 8p, 11f, 11n), (b) those producing about 1.3 mole lactic acid/mole glucose (strains 1e and 11b), (c) those producing acid but not lactic acid (strain 11g), (d) those unable to ferment glucose (strains 1a, 1d and 9a). This grouping of strains agrees well with groupings based on other biochemical criteria.

Level of Vitamin B12 in Propionate-grown Prototheca zopfii

THE colourless alga Prototheca zopfii does not require vitamin B12 as a growth factor, whereas at least half the marine algal flagellates and diatoms which have been investigated in pure culture1, the protozoan flagellate Ochromonas malhamensis2, and Euglena gracilis3, have all been shown to have a growth requirement for this compound.

Inhibition of electron transport in Prototheca zopfii

The effects of a number of inhibitors on the respiration of the colourless alga, Prototheca zopfii, have been studied, and twenty-six compounds related to rotenone tested as inhibitors of NADH oxidase. The results are compared with those obtained with other algal systems and the mammalian respiratory chain.

An Adaptive Butyrase Enzyme System in the Alga Prototheca zopfii

ANDERSON1 reported that Prototheca zopfii, which is a colourless alga, was able to assimilate most of the monosaccharides, and all the fatty acids with the exception of formic, isovaleric and pyruvic acids. Pyruvate could, however, become assimilated if the pH. were lowered to 4.5, and this also affected the rate of oxidation of the carbon energy source.

The purification and properties of malonic semialdehyde oxidative decarboxylase from Prototheca zopfii

1. An enzyme, which in the presence of NAD(+) and CoA oxidizes malonic semialdehyde to acetyl-CoA, has been purified from an extract of the colourless alga Prototheca zopfii. 2. The purified enzyme has optimum pH7.5, is specific for NAD(+) and requires a thiol compound for maximum activity. 3. The enzyme is inhibited by arsenite, N-ethylmaleimide and urea. 4. The results are discussed in relation to those obtained by other workers with a similar bacterial enzyme, and a possible reaction sequence is proposed.

Reversal by Histidine of the Inhibition of Prototheca Growth due to 3-Amino-1,2,4-triazole

3-AMINO-l,2,4-triazole (amitrole) is used as a systemic herbicide. It also inhibits the growth of a number of micro-organisms including several algae. Organic acids have long been known to inhibit the growth of algae by combining with iron1. Aaronson2 concluded that amitrole was also working in this way as the inhibition of Ochromonas danica could be abolished by the supply of extra iron to cultures in the presence of the inhibitor. Later Wolf3, examining Chlorella pyrenoidosa, and Boney4 certain marine red algae, reported that the inhibition by amitrole could be reversed by adenine. In this the algae are similar to Escherichia coli5. Histidine is effective in releasing the inhibition of Torula cremoris5 and of Saccharomyces cerevisiae6. Since the standard medium used by Aaronson contained histidine7, an investigation of the reversal of amitrole toxicity towards Prototheca zopfii was carried out. This colourless alga is believed to be closely related to Chlorella and it will grow in a mineral medium supplemented with glucose and thiamine8. Aaronson and Scher7 showed that there was no significant difference in the concentration of amitrole required to achieve inhibition of Euglena and Ochromonas growth in the presence of an organic substrate in the dark as compared with the light although chlorophyll synthesis was inhibited.

NATURE OF THE GROWTH FACTOR FOR THE COLORLESS ALGA PROTOTHECA ZOPFII

Barker's study on the nutritive requirements of Prototheca zopfii indicated that this colorless alga fails to grow in the absence of small amounts of yeast extract. A study of the growth factor requirements of Prototheca has shown that the active constituent of yeast extract necessary for the growth of this organism is thiamin (vitamin B(1)). Thiamin can fully replace the complex yeast material and allows, in the basal medium used, a maximum cell yield in concentrations of 1-3 x 10(-7)M. Thiamin as such, however, is not essential for the growth of Prototheca zopfii. The alga can develop equally well if supplied with both the thiazole and pyrimidine constituents of this vitamin. These appear to be needed in equimolar proportions. Maximum cell yield is obtained with 3 x 10(-8)M concentrations of the two components.