The salt relations of Dunaliella

Dunaliella tertiolecta (marine) and D. viridis (halophilic) were each trained by serial transfer to growth at salt concentrations previously regarded as the other's domain. D. viridis then had a salt optimum at 1.0–1.5 M sodium chloride whereas that for D. tertiolecta was less than 0–2 M. Nevertheless D. tertiolecta grew faster than the halophil at all salt concentrations up to 3.5 M, the highest at which they were compared.Both species accumulate glycerol, which is necessary for growth at elevated salinities and which responds in its content to water activity (a _w ) rather than specifically to salt concentration. Variation in glycerol content is a metabolic process which occurs in the dark from accumulated starch as well as photosynthetically. Regulation of glycerol content by a _w does not require protein synthesis. The NADP-specific glycerol dehydrogenase of each of the algae is likely to be directly involved in the regulation of glycerol content. Kinetic studies, together with those described in an earlier publication, show that the enzyme has regulatory properties, and that both glycerol and dihydroxyacetone act as effectors as well as reactants. A mechanism of the reaction is tentatively proposed.     

Seasonal variation in the biochemical composition of Mytilus viridis at Ratnagiri on the West Coast of India

1. The seasonal variation in the water, protein, fat and glycogen contents of the mussel, Mytilus viridis has been studied for the year March, 1974 to March, 1975.
2. The water level increased during the monsoon season and decreased in summer.
3. The level of protein, fat and glycogen showed correlation with the reproductive cycle of the mussel.
4. The protein level was high when the mussels were mature and dropped during the breeding period.
5. During sex change from male to female in May the protein level remained high whereas during sex change from female to male in October and November it was low.
6. The fat level was high in mature mussels and declined on spawning.
7. The glycogen level was at its peak in immature mussels and low in mature.

     

Anuran amphibia which are not acclimable to high salt,tolerate high plasma urea

• 1.1. The capacity of five anuran Amphibians (Bufo viridis B. regularis, Rana ridibunda, Hyla arborea and Pelobates syriacus) to acclimate to NaCl and urea solutions was investigated.
• 2.2. All species could be acclimated to relatively high concentrations of urea solutions, while only Bufo viridis and Hyla arborea could be acclimated to 500 mOsm/kg or higher NaCl solutions.
• 3.3. The plasma urea concentration in B. viridis and H. arborea was elevated to levels over 140 mmol/1.
• 4.4. The sum of plasma sodium and chloride concentrations did not increase over 400 mmol/l in any species.
• 5.5. Urine osmolality, which was normally low, increased, but never exceeded the plasma osmolality.
• 6.6. In the urea acclimation conditions, urine electrolytes diminished, similarly in all species in this study.
• 7.7. It is concluded that anuran Amphibians can tolerate high plasma urea concentrations, but only those species which can elevate it, either through retention or net synthesis, can be acclimated to high salt solutions.

     

Aerobic and anaerobic growth of Paracoccus denitrificans on methanol

1. The dye-linked methanol dehydrogenase from Paracoccus denitrificans grown aerobically on methanol has been purified and its properties compared with similar enzymes from other bacteria. It was shown to be specific and to have high affinity for primary alcohols and formaldehyde as substrate, ammonia was the best activator and the enzyme could be linked to reduction of phenazine methosulphate.
2. Paracoccus denitrificans could be grown anaerobically on methanol, using nitrate or nitrite as electron acceptor. The methanol dehydrogenase synthesized under these conditions could not be differentiated from the aerobically-synthesized enzyme.
3. Activities of methanol dehydrogenase, formaldehyde dehydrogenase, formate dehydrogenase, nitrate reductase and nitrite reductase were measured under aerobic and anaerobic growth conditions.
4. Difference spectra of reduced and oxidized cytochromes in membrane and supernatant fractions of methanol-grown P. denitrificans were measured.
5. From the results of the spectral and enzymatic analyses it has been suggested that anaerobic growth on methanol/nitrate is made possible by reduction of nitrate to nitrite using electrons derived from the pyridine nucleotide-linked dehydrogenations of formaldehyde and formate, the nitrite so produced then functioning as electron acceptor for methanol dehydrogenase via cytochrome c and nitrite reductase.

     

The anaerobic metabolism of malate of Saccharomyces bailii and the partial purification and characterization of malic enzyme

1. The main pathway of the anaerobic metabolism of l-malate in Saccharomyces bailii is catalyzed by a l-malic enzyme.
2. The enzyme was purified more than 300-fold. During the purification procedure fumarase and pyruvate decarboxylase were removed completely, and malate dehydrogenase and oxalacetate decarboxylase were removed to a very large extent.
3. Manganese ions are not required for the reaction of malic enzyme of Saccharomyces bailii, but the activity of the enzyme is increased by manganese.
4. The reaction of l-malic enzyme proceeds with the coenzymes NAD and (to a lesser extent) NADP.
5. The K _m-values of the malic enzyme of Saccharomyces bailii were 10 mM for l-malate and 0.1 mM for NAD.
6. A model based on the activity and substrate affinity of malic enzyme, the intracellular concentration of malate and phosphate, and its action on fumarase, is proposed to explain the complete anaerobic degradation of malate in Saccharomyces bailii as compared with the partial decomposition of malate in Saccharomyces cerevisiae.

     

Correlation of the effects of citric acid cycle metabolites on succinate oxidation by rat liver mitochondria and submitochondrial particles

1. Succinate dehydrogenase is inhibited by citrate and β-hydroxybutyrate in a complex manner, both in mitochondria and submitochondrial particles. Kinetics of inhibition in the particles points to a competitive component in the mechanism involved.
2. Pyruvate, α-ketoglutarate, malate, and glutamate stimulate oxidation of succinate by mitochondria.
3. Stimulation by α-ketoglutarate and glutamate is not influenced by the presence of rotenone.
4. Stimulation by pyruvate is higher in the absence of rotenone and increases significantly in the presence of K⁺ and valinomycin. Pyruvate supplies in mitochondria reducing equivalents for malate dehydrogenase operating in the reverse direction-reduction of oxaloacetate to malate.
5. Stimulation by malate is higher in the presence of rotenone.

     

Metabolism of the anaerobic formation of succinic acid bySaccharomyces cerevisiae

1. Succinic acid is formed in amounts of 0.2–1.7 g/l by fermenting yeasts of the genusSaccharomyces during the exponential growth phase. No differences were observed between the various species, respiratory deficient mutants and wild type strains.
2. At low glucose concentrations the formation of succinic acid depended on the amount of sugar fermented. However, the nitrogen source was found to be of greater importance than the carbon source.
3. Of all nitrogen sources, glutamate yielded the highest amounts of succinic acid. Glutamate led to an oxidative and aspartate to a reductive formation of succinic acid.
4. A reductive formation of succinic acid by the citric acid cycle enzymes was observed with malate. This was partially inhibited by malonate. No evidence was obtained that the glyoxylate cycle is involved in succinic acid formation by yeasts.
5. Anaerobically grown cells ofSaccharomyces cerevisiae contained α-ketoglutarate dehydrogenase. Its activity was found in the 175000 x g sediment after fractionated centrifugation. The specific activity increased 6-fold after growth on glutamate as compared with cells grown on ammonium sulfate.
6. The specific activities of malate dehydrogenase, fumarase, succinate dehydrogenase, succinylcoenzymeA synthetase, α-ketoglutarate dehydrogenase and glutamate dehydrogenase (nicotinamide adenine dinucleotide dependent) were determined in yeast cells grown on glutamate or ammonium sulfate. Similar results were obtained with a wild type strain and a respiratory deficient mutant. The latter did not contain succinate dehydrogenase.
7. In fermenting yeasts succinic acid is mainly formed from glutamate by oxidation.

     

Control of derepressed β-galactosidase synthesis inEscherichia coli

1. The synthesis of β-galactosidase in a constitutive mutant ofEscherichia coli (ML 308, i^-z⁺y⁺a⁺) responds to the nutritional environment. Repression can be reversed by cyclic AMP.
2. The greatest degree (%) of repression by metabolisable compounds is obtained when cells utilising glycerol (0%) are given, in addition, pyruvate (67%), serine (57%) which can be converted to pyruvate, or substrates of phosphotransferase systems (20–40%) which liberate pyruvate in their operation. Furthermore, pyruvate represses β-galactosidase synthesis in a phosphoenolpyruvate synthaseless mutant. Pyruvate, however, does not repress in a pyruvate dehydrogenaseless mutant and it follows that pyruvate itself is not the agent of repression.
3. Raffinose, a non-metabolisable galactoside, represses synthesis of β-galactosidase during growth on glycerol. Over a wide range, repression depends on raffinose concentration as does a lowered pool of ATP, rate of oxygen consumption and growth rate. All these parameters are inter-related but, in particular, β-galactosidase synthesis depends on the size of the ATP-pool presumably because this also limits synthesis of cyclic AMP under these conditions.

     

Succession in Zoo- and phytoplankton in a sewage stabilization pond

The investigations pertaining to zoo- and phytoplankton succession during prestabilization and stabilization of domestic waste water in a facultative pond operating at 1.22 meters depth with an average BOD loading of 336.3 kg per hectare per day and a retention period of 10 days revealed the following:

1. A photosynthetic sulphur bacterium Thiocystis violacea has been recorded during the second and third day along with a considerable population of ciliate protozoa and algae.
2. Chlorophytes were followed by euglenoids in the ecological succession and the latter became predominant after the pond stabilized.
3. Of the twelve protozoan species Halteria grandinella, Bursaria truncatella and Perispira ovum were associated with peaks of algae and vigorous photosynthesis in the stabilized pond water.
4. There ia a gradual improvement in the quality of the waste water with respect to reduction in bacteria and biochemical oxygen demand and enhancement in changes in physico-chemical factors till a relatively stable community is evolved.

     

Summer algal communities and primary productivity in fish ponds

The paper presents data on primary productivity and phytoplankton communities in new experimental ponds which received the following treatments; ammonium nitrate and triplesuperphosphate, triplesuperphosphate, cracked corn (10% crude protein) and Auburn No. 3 fish feed (36% crude protein). Comparative data on algal communities were also obtained from production ponds which received feeds or fertilizers. Basic ecological data on macro-algae are also presented.

1. All nutrient additions to experimental ponds resulted in higher levels of gross photosynthesis and greater concentrations of chlorophyll a than were found in the control treatments. Fertilization with both nitrogen and phosphorus gave the highest values. Chlorophyll a and gross photosynthesis were higher in ponds receiving high protein content feed (Auburn No. 3) than in ponds to which low protein content feed (corn) was applied.
2. Persistent blooms of blue-green algae occurred in ponds receiving nitrogen and phosphorus fertilization. Phosphorus only fertilization produced blooms of blue-greens, but these blooms did not persist as in the ponds to which nitrogen was also added. Control ponds were dominated by green algae. Blue-green algae were seldom abundant in feed treatments.
3. Production ponds had high level of gross photosynthesis and large concentrations of chlorophyll a.
4. Many of the production ponds which received feed applications developed heavy blooms of blue-green algae.
5. The major species of blue-green algae observed in the present study were Oscillatoria sp., Raphidiopsis curvata, Anacystis nidulans, A. aeruginosa, Spirulina sp., and Anabaena circinalis. Heterocyst bearing forms, which can presumably fix nitrogen, were seldom noted in ponds that received continuous additions of nitrogen from fish feeds.
6. Macro-algae are abundant in many fish ponds. Data illustrating the competition of macro-algae with phytoplankton are presented.

     

Peculiarities of growth of the monocellular green algae culture after the influence of electromagnetic field in deuterated water-containing media

Exposing the inoculum of monocellular green algae Dunaliella tertiolecta and Tetraselmis viridis to 50 Hz electromagnetic field for several hours resulted in a reduced growth rate in both cultures. It was ascertained that heavy water inhibited growth of algae Dunaliella tertiolecta. The light water activated growth of the culture in the exponential phase only.     

Function of laccase in the white-rot fungus Fomes annosus

1. Thioglycolic acid, a Cu-chelating agent, totally inhibited extracellular laccase activity without affecting growth and morphology of Fomes annosus.
2. In the presence of thioglycolic acid Fomes annosus cleaved high molecular weight lignosulfonate with a molecular weight range of 2×10⁶ to 1000. In the absence of thioglycolic acid the polymerizing activity of laccase prevented the detection of lignosulfonate breakdown products.
3. Oxidative polymerization of a lignin monomer, coniferyl alcohol, occurred in the presence but not in the absence of laccase activity.
4. Catechol and guaiacol added to the medium at a concentration of 2 mmol, are normally oxidized by fungal laccase and strongly inhibit growth. Presence of thioglycolic acid prevented the oxidation of these phenols and simultaneously permitted normal growth.

     

The use of a continuous assay system to show the stimulation of phosphoenolpyruvate production in intact mitochondria by valinomycin and by Mn2+

1. A method for the direct recording of the PEP efflux from isolated mitochondria is described.
2. This method has been used to show the stimulation of PEP efflux by externally added Mn⁺⁺ ions.
3. Valinomycin, uncoupler and oleate were also shown to stimulate PEP efflux.
4. Valinomycin caused an increase in the internal concentration of both PEP and citrate.
5. The results indicate that the major pathway of PEP synthesis in isolated mitochondria is via PEP carboxykinase and the results do not call for an unknown pathway of metabolism.
6. Two interactions between PEP and citrate are described; competition for the mitochondrial interior and the stimulation of PEP production by citrate.

     

Effects of the discharge of thermal effluent from a power station on Lake Wabamun,Alberta, Canada — The epipelic and epipsamic algal communities

1. The epipelic algal standing crops were increased by the discharge of thermal effluent into Lake Wabamun, particularly in the discharge canal at station (03–04) and 05.
2. The increase in the standing crop size of the epipelon was due to Oscillatoria amoena and O. borneti in the heated area, while the discharge canal provided the inoculum of the algae for the heated area of the lake.
3. At station (03–04) the increased standing crop size was also a function of increased light penetration to the sediment due to the heated effluent keeping an area of the lake free of ice during the winter.
4. The species composition of the diatoms was similar at all stations except in the discharge canal where there was a reduction in the number of diatom species.
5. Navicula cuspidate developed best in the discharge canal in the summer where water temperatures of 31°C were recorded.
6. Amphora ovalis var. pediculus was the dominant diatom species during the winter under ice-cover.
7. The heated effluent had no effect upon the standing crop or species composition of the epipsammon.
8. Results obtained from the sediment core study showed that the shallow littoral zone of the lake is very disturbed due to wind-induced wave action.

     

The role of mitochondria in modifying the cellular inoc environment: Studies of the kinetic accumulation of calcium by rat liver mitochondria

1. The affinity of ATP-supported Ca²⁺ accumulation for both Ca²⁺ and ATP was determined from initial rate studies employing isolated rat liver mitochondria. TheK _m values for “free” Ca²⁺ and ATP were calculated to be of the order of 2 μM and 100 μM, respectively. TheK _m for ATP decreased as the Ca²⁺ concentration was increased.
2. The curve relating initial rates of Ca²⁺ accumulation to Ca²⁺ concentration was singmoidal in shape; values obtained for the Hill coefficient were in the range 1.5–1.9.
3. Concomitant with the ATP-stimulated accumulation of Ca²⁺, ATP translocation was itselt increased in the presence of Ca²⁺. This stimulation took place independently of Ca²⁺ accumulation.
4. Decreasing the pH of the incubation medium decreased the rate of Ca²⁺ accumulation. This inhibition was competitive in that the affinity of mitochondrial for Ca²⁺ could be altered. The maximal rate of accumulation did not change with change in pH.
5. The permeant anions inorganic phosphate and acetate stimulated the accumulation of Ca²⁺ in a non-competitive manner. Both theV _max and K_m varied when either of the anions were present.
6. The data are discussed in relation to the role that mitochondria play in controlling the cellular ionic environment.

     

Charakterisierung eines phagenähnlichen Partikels aus Zellen von Nitrobacter

1. Polyhedral particles were isolated from cells of Nitrobacter winogradskyi and of Nitrobacter strains K₁, K₄ and α₁. Their physical and biological properties are characterized.
2. The investigated strains contain polyhedral particles, 1000–1200 Å in size. With increasing age of the culture more particles are found in cells of Nitrobacter. Simultaneously the number of colony producing nitritoxidants decreases.
3. In strain α₁ the loss of the capability to form colonies is connected with partial lysis of the cell and release of particles.
4. A homogeneous fraction of particles was obtained by zone density gradient centrifugation in Tris-Mg-SH-buffer.
5. The polyhedral particles have a sedimentation coefficient of s _w,20 ⁰ =825S and a CsCl-buoyant density of ?²⁵ g/cm³.
6. Based on the determined properties the particles are classified as phage-like Nitrobacter particles Nb₁.

     

Uptake of guanine by synchronizedChlorella fusca

1. The transport of guanine in autospores of light-dark synchronizedChlorella fusca was studied using radioactive guanine in the concentration range of 4 nM to 50 μM.
2. The transport system was constitutive, it had high specificity for the permeant, and theQ ₁₀ value was in the range of 1.5 to 2.2. At concentrations lower than 0.2 μM the half saturating constant, S_0.5 was 1 μM both for cells kept in dark and cells kept in light. At higher concentrations the S_0.5 of darkened cells was about 0.23 μM, while that of illuminated cells was unchanged. Only above 0.2 μM guanine did illumination of the cells or addition of glucose increase the transport rate.
3. Guanine which had accumulated did not leak out at temperatures below 45°C or by treatment with 10 μM dinitrophenol, which completely inhibited transport. Furthermore, the accumulated guanine did not exchange with exogenous guanine.
4. The guanine accumulated, more than 10⁵-fold over the external concentration, showing that the transport, was active.
5. The initial transport rate per cell revealed annual fluctuations.

     

An ecological study of three freshwater ponds of hyderabad-India III. The phytoplankton (Volvocales,Chlorococcales, and Desmids)

The present paper deals with the ecological behaviour of green algae (Volvocales, Chlorococcales and desmids) of certain freshwater ponds, studied over a period of two years. The distributional patterns and periodicity of the various forms were compared with the changes in chemical constituents of water. The following conclusions were drawn.

1. Volvocales preferred eutrophic waters having high salt content. Their periodicity was possibly dependent upon the concentrations of nitrates and phosphates.
2. Chlorococcales were present in both, the calcium-rich and Calcium-poor ponds but the species composition was totally different from each other.
3. The ecology of desmids was possibly linked with the iron content and Divalent Monovalent ratio of water.

     

Field studies on the variability of populations of Aster tripolium L. in relation to saltmarsh zonation

1. Aster tripolium is a very variable species of which a number of types have been described both on a morphological and ecological level.
2. In permanent plots along the height gradient in the salt marsh it appeared that differences in the A. tripolium subpopulations occur.
3. In the lowest zone of the marsh, dominated by Spartina anglica (Spartinion), the mean life expectancy of individual adult plants is relatively high but it is relatively low for seedlings.
4. In the higher zones of the marsh the mean life expectancy is relatively lower, but for the seedlings it is higher (Puccinellion maritimae).
5. In the Spartina-zone individual A. tripolium plants have about twice the number of shoots as the plants from the other zones.
6. The plants from the Spartina zone produce per individual more generative shoots (absolute) but these have less capitula than elsewhere in the marsh. The number of ripe seeds per head is almost constant everywhere in the marsh.

     

Acid-base titration across the plasma membrane ofMicrococcus denitrificans: Factors affecting the effective proton conductance and the respiratory rate

The object of this work was to measure the effective proton conductance of the plasma membrane ofMicrococcus denitrificans under various conditions and to investigate possible connections between respiration and proton translocation.

1. Pulsed acid-base titrations of suspensions ofM. denitrificans in a medium containing the permeant thiocyanate ion, or when K⁺ ion permeability was induced by valinomycin in a KCl medium, showed that the normal effective proton conductance of the membrane system was less than 1 μmho/cm².
2. A pH-overshoot artefact was suppressed by adding carbonic anhydrase.
3. The effective proton conductance was increased by the uncoupler FCCP in the same concentration range as was required to stimulate respiration. Concentrations of FCCP above 1·5 μM inhibited respiration after an initial stimulation.
4. The effective proton conductance in presence of 2 μM FCCP was at least 17 μmho/cm².
5. The quantitative relationships between the respiratory rate, the stoichiometry of respiration-driven proton translocation, and the effective proton conductance of the membrane of the cells are compatible with the suggestion that stimulation of respiration by FCCP is due to a release of back-pressure exerted by a protonmotive potential on the respiratory chain system in the membrane. Only one amongst other possible explanations of the stimulation of respiration by FCCP is, however, excluded.