Charkterisierung eines phagenähnlichen Partikels aus Zellen von Nitrobacter

1. Phage-like particles Nb₁ isolated from cells of Nitrobacter agilis were characterized after freeze etching and after treatment by fixation agents.
2. Ethanol-acetic acid fixed particles can be digested by the proteolytic enzyme papain.
3. Ethanol-acetic acid fixed particles show a loss in mass and volume after treatment with DNase. Under the same conditions RNase has no influence.
4. The chemical composition of the phage-like particle Nb₁ is discussed.

     

Adenine nucleotide pool variations in intact Nitrobacter winogradskyi cells

1. The ATP pool in Nitrobacter winogradskyi cells was determined by means of the luciferin-luciferase enzyme system and the ADP and AMP pools were measured after enzymatic conversion into ATP.
2. In the fist 10 min after addition of nitrite to endogenously respiring cells, which had stood for 5–16 days after completion of the nitrite oxidation, the ATP pool dropped about 60%.
3. During the log phase the ATP pool was approx. 20–40 pmoles/5 μg cell-N. During growth it increased exponentially by 3–4 times the amount until the nitrite had been used up. Subsequently the ATP pool decreased at first rapidly and then more slowly without sinking to 0 in the first 2 months after nitrification.
4. Nitrite oxidizing cells had an energy charge of 0.37 during the log-phase. After approx. 90% of the substrate had been used up the energy charge had reached 0.57.
5. If the CO₂ assimilation was inhibited in growing cultures by increased oxygen partial pressure, nitrite oxidation continued but the ATP pool increased.
6. The ATP pool and the activity of the endogenous respiration decreased by more than 50% during the first hours after the substrate had been used up.

     

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.

     

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.

     

Study of the regulation of oxidation and CO2 assimilation in intact Nitrobacter winogradskyi cells

1. Changes of the adenine nucleotides in resting and growing Nitrobacter winogradskyi cells were measured in connection with regulating processes during nitrite oxidation and endogenous respiration.
2. After the addition of nitrite to endogenously respiring cells the ATP pool increased strongly during the first 60 sec at the expense of the ADP pool. At this point the energy charge was approx. 0.55. After the first 90 sec the ATP pool dropped, oscillating, to a lower level. The CO₂ assimilation began at this point.
3. Under a nitrogen atmosphere the AMP pool increased and the ATP pool decreased. With a value of approx. 0.17 the energy charge was extremely low. When oxygen was added the Nitrobacter cells began to oxidize stored NADH. The ATP pool increased in a few seconds whereas the AMP pool decreased. The P/O ratio of endogenously respiring cells equaled 0.6 under these conditions.
4. During the changeover from anaerobic to aerobic conditions and in the presence of nitrite the nitrite oxidation and CO₂ assimilation, opposed to aerobic conditions, were inhibited at first after the nitrite addition. The changeover of the respiratory chain enzymes from a reduced to an oxidized charge and the ATP increase were delayed in comparison with experiments without nitrite. According to these findings the endogenous respiration must be almost nil while nitrite oxidizing cells are growing.

     

Chemolithotrophic growth and regulation of hydrogenase formation in the coryneform hydrogen bacterium strain 11/x

1. The present paper deals with the chemolithotrophic growth of a Gram-positive hydrogen bacterium strain 11/x which shows the characteristic features of some coryneform bacteria.
2. Like other hydrogen bacteria, the strain 11/x is a facultative chemolithotroph and grows on many organic substrates faster than in a mineral medium under an atmosphere of knallgas+CO₂. Fully induced, autotrophically grown cells, subcultured mixotrophically on fructose show additive growth.
3. Cell-free extracts of autotrophically grown cells are able to reduce methylene blue, dichlorophenolindophenol, phenazine methosulphate, menadione, and FMN with hydrogen. Conditions for direct NAD(P) reduction could not be found.
4. Hydrogenase is formed under autotrophic as well as mixotrophic conditions. In the latter case the rate of hydrogenase formation is diminished depending on the organic substrate. Heterotrophically grown cells do not have any detectable hydrogenase activity. For the induction of hydrogenase in those cells a nitrogen source is a prerequisite.
5. The formation of ribulose-1,5-diphosphate carboxylase and phosphoribulokinase seems to be regulated in a way similar to that of hydrogenase: the enzymes could only be detected in autotrophically and mixotrophically grown cells but not in those grown heterotrophically.

     

Oxaloacetate decarboxylase from Acetobacter aceti

An oxaloacetate (OAA) decarboxylase (EC 4.1.1.3) has been purified 72-fold from Acetobacter aceti cells grown on ethanol, and its molecular weight was estimated to be about 80,000 by gel filtration. Several properties distinguished this enzyme from the OAA decarboxylase from A. xylinum:

1. It was not a constitutive enzyme; the activity was 6- to 20-fold higher in cells grown on a C₂ substrate (acetate or ethanol) than in cells grown on a C₃ compound (pyruvate or propionate).
2. The optimum pH was 7.5; a value of 5.6 was reported for the enzyme from A. xylinum.
3. The enzyme did not need a divalent cation and was not inhibited by EDTA.
4. The K _mvalue for OAA was found to be 0.22 mM. It was not affected by the addition of nicotinamide adenine dinucleotide.
5. The enzyme activity was neither inhibited by acetate nor by L-malate.

In addition, the OAA decarboxylase from A. aceti was insensitive to monovalent cations, avidin or acetyl coenzyme A.     

Amino acid receptor sites in the facial taste system of the sea catfish Arius felis

1. The amino acid sensitivity and specificity of the facial taste system of the marine catfish, Arius felis, is characterized electrophysiologically.
2. The facial taste system of Arius felis responded to all 28 amino acids tested, but was highly sensitive to only a few. In general, acidic amino acids and neutral amino acids with short side chains were more effective than imino, basic and neutral amino acids with long side chains.
3. A reciprocal cross-adaptation protocol used to characterize the receptor sites identified at least some relatively independent receptor sites for L-arginine, L-histidine, L-proline, L-alanine, glycine, D-alanine and L-glutamate.
4. Of the 7 amino acids that were indicated to have relatively independent receptor sites, the median electrophysiological threshold for L-alanine, the most stimulatory, and L-proline, the least stimulatory compounds, were 10 nM and 10,000 nM, respectively. The integrated facial taste response did not saturate at test amino acid concentrations up to 10 mM.
5. The generalized depression in responsiveness to test stimuli observed during amino acid adaptation is proposed to be a result of the co-distribution of sensitivity at the level of single taste cells rather than high cross-reactivity of the respective amino acid receptor sites for the test stimuli.

     

Molybdenum and iron as functional constituents of the enzymes of the nitrate-reducing system of Azotobacter chroococcum

The roles of molybdenum and iron in the enzymes of the assimilatory nitrate-reducing system from Azotobacter chroococcum have been investigated.

1. By adding ⁹⁹Mo-molybdate to a cell culture of A. chroococcum with nitrate as the nitrogen source, it has been possible to inccrporate the radioactive metal into a purified preparation of the enzyme nitrare reductase.
2. When ¹⁸⁵W-tungstate was supplied to a culture medium lacking added molybdate, a ¹⁸⁵W-labelled nitrate reductase preparation with negligible activity could be obtained. This in vivo incorporation of tungsten was competitively hindered by molybdenum.
3. The cellular level of nitrite reductase activity gradually increased in response to the addition of increasing amounts of iron to the culture medium. Under the same conditions, the level of nitrate reductase activity was not affected.

     

A study on the rate of water transport of the clam katelysia opima in relation to environmental conditions

1. The neutral red technique was employed to study the rate of filtration in Katelysia opima.
2. The weight specific water filtration was found to be greater for younger clams compared to the older ones.
3. The rate of water filtration increased with decreasing salinity.
4. Water filtration was found to increase as temperature increased, reaching a maximum at 35°C. but then sharply decreasing at 39°C.
5. Light had no significant effect on the rate of filtration.
6. Suspended matter was found to affect the rate of water filtration.
7. The rate of filtration was low at high pH and high in low pH.
8. The rate of water filtration was found to be faster during high tide than during low tide.
9. The presence of the parasitic crab, Pennotheris sp., in the mantle cavity of clams had a marked effect on the particle filtration.
10. Accidental cut of the siphon tips had no effect on the rate of filtration.

     

Les brisures de symetrie du temps

Introduction

Atoms theory and symmetry theory dominated physics. Symmetry propagation and interactions verify the Curie principle. But its violation by symmetry breaking is spontaneous.Fragility is creative. An information breaks a generalized symmetry. Results on symmetry breakings are not valid for fuzzy symmetries. The breaking of a fuzzy symmetry leads only to a pour symmetry (Fig.1). Homogeneity breaking, and atom of time are not usual concepts. We examine in this work symmetry breakings which generate the living time.

Relativistic Time-Space Breaking

1. Medium and environment of living define ordinary referential of space and referential of time. Astronomical phenomena following classical mechanics and microphysical phenomena following quantum mechanics can be written with the same t coordinate.
2. Relativity corrections. Schrödinger's Quantum mechanics (Eq.0) approximately governs molecular systems (Relativity corrections can be expressed as physical effects in the above defined referential).
3. Time reversal symmetry. The well-known Wigner's transformation determines the microscopic reversibility.
4. The three essential particle-vacancy equilibria. This transformation is verified by all particle-vacancy reciprocity. Vacancy moves like particle but with negative moment and positive kinetic energies. Only three biochemical equilibria admit this time reversal symmetry, namely: oxydo-reduction, acido-basicity, fluidity-viscosity. In these case, reacting electron, solvated proton, water molecule are respectively antagonist of the corresponding vacancy.
5. Fuzzy character of time reversal symmetry. Dirac's equation does not admit this symmetry which only appears at the “non relativistic” limit of quantum phenomena. Hence particle-vacancy reciprocity is fuzzy according to the experimental evidence. (Laforgue et al., 1988).

Oriented Time

1. From the universal reversible time, an additional breaking generates the oriented time, both in the astronomical and in the living matter.
2. Irreversibility for the environment. We refer to Prigogine and Stengers (1988).
3. Irreversibility for the living matter. We refer to Lochak (1986). Because equation (0), above discussed, is “microreversible” the second breaking could come from an additional term vanishing in the stationary states but increasing with time in evolutionary processes.
4. Negative times. Taking into account the fuzzy character of the time reversed symmetry, the third breaking cannot suppress completely the occurrence of negative times. Reversed time is controlled by direct time. Except in the three above reported cases, time reversal symmetry is not verified by the medium. Free motion of the particle following eg.(0) or of the vacancy following time reversal reciprocal equation takes place only during short jumps from an interaction site to an other. Fig. 2 schematizes the law of motion of the electric charge corresponding to the transport by proton or by proton vacancy in an unitary field (fluctuations are neglected). The reserved jumps are estimated in the range of 10^?12s. It is not excluded that such a jump can control a direct phenomenon.
5. The living time. Biological phenomenon appears as an oriented set of events. Nevertheless latency or exaltation phases could be perceived. This modulation could be described by positive and negative times additional to the basic time. (Negative can be interpreted as above)

Living produces Time

1. That were not understandable, if time was only a frame, in which change occurs. Taking chance as frame and time as effect, we regard biological activity as integrating reversible and irreversible time. Living synchronizes internal and external time by its own effort as it results (Lestienne, 1990) from Chronobiology.
2. Time modulation. Let us consider the dy₁...dy_i...dy_p changes in the variables of the systems, dy={dy_i} has produced dt. We proof (eq.(1) to (4)) that time is modulated by a φ_(y) speed coefficient depending on the medium. t_modulated=tφ _(y) ^?1
3. The production of reversible time (e.g.acido-basicity) determines time modulation. As above reported it remains some reversibility effects (jumps of negative time) which modulate time. E.G., if an important amount of reagent is necessary to modify an acid-base equilibrium, φ_(y) is small.
4. Time modulation and activation-repression reciprocity. As well-known, long t_modulated means repression, short t_modulated means exaltation. Extrema of ? are symmetrical because particle and vacancy are reciprocal. Nevertheless reciprocity is not perfect. E.g., on fig. 3, the wet receptor determines the cell increasing, the dry receptor the cell senescence of a certain alga (Lück, 1962).
5. Irreversible time production. Medium accepts entropy. Hence it acts in the second breaking of time. Living extracts the free energy from the medium, like a dissipative structure. That insures an operative point far from the thermodynamical equilibrium.

Consumption of Time

1. The three followings correspond to the more trivial time consumption.
2. Rhythmical time. Free energy flux is favourable to the arising of order in space or time. This later gives a structure to the living time.
3. Mutual dependence of reversible time and rhythms. Time irreversible structure can be controlled by the above considered particle-vacancy equilibrium. Consequently the living time (modulated and structured) is a chemical time connected to molecular properties and to statistical thermodynamics. Practically, the connection between chronobiology and chemistry is important. The use of drugs could be interpreted as a response to an aggression against biorhythms.
4. Lifetime. The dead-birth rythm can be broken in two ways: evolution or indefinite life. This later is non exceptional for the living matter, e.g. in the vegetals where it is connected with the chlorophyllic assimilation; the time reversal significance of which is evident.
5. The plan of the alchemist. Indefinitely life has fascinated individuals. Do the human species becomes better adapted by a longer life?

Conclusions

1. Atoms of time could exist.
2. Biological time is defined by the breaking of five generalized symmetries, namely: Minkovski's space symmetry, reversibility, homogeneity, rhythmicity, generations reproduction.
3. Environment and medium determine non relativistic, oriented, structured time.
4. At the microphysical scale, a fuzzy time reversal symmetry takes place, the breaking of which is not complete. Reversible time and dominating irreversible time are integrated in living phenomena.
5. Three fundamental particle-vacancy reciprocities admit a part of reversibity. Irreversibility governs the all others phenomena.
6. Time is produced chemically.
7. A new perspective is the connection between chemical equilibria and rhythms including the time of the life.

     

Les brisures de symetrie du temps

Introduction

Atoms theory and symmetry theory dominated physics. Symmetry propagation and interactions verify the Curie principle. But its violation by symmetry breaking is spontaneous.Fragility is creative. An information breaks a generalized symmetry. Results on symmetry breakings are not valid for fuzzy symmetries. The breaking of a fuzzy symmetry leads only to a pour symmetry (Fig.1). Homogeneity breaking, and atom of time are not usual concepts. We examine in this work symmetry breakings which generate the living time.

Relativistic Time-Space Breaking

1. Medium and environment of living define ordinary referential of space and referential of time. Astronomical phenomena following classical mechanics and microphysical phenomena following quantum mechanics can be written with the same t coordinate.
2. Relativity corrections. Schrödinger's Quantum mechanics (Eq.0) approximately governs molecular systems (Relativity corrections can be expressed as physical effects in the above defined referential).
3. Time reversal symmetry. The well-known Wigner's transformation determines the microscopic reversibility.
4. The three essential particle-vacancy equilibria. This transformation is verified by all particle-vacancy reciprocity. Vacancy moves like particle but with negative moment and positive kinetic energies. Only three biochemical equilibria admit this time reversal symmetry, namely: oxydo-reduction, acido-basicity, fluidity-viscosity. In these case, reacting electron, solvated proton, water molecule are respectively antagonist of the corresponding vacancy.
5. Fuzzy character of time reversal symmetry. Dirac's equation does not admit this symmetry which only appears at the “non relativistic” limit of quantum phenomena. Hence particle-vacancy reciprocity is fuzzy according to the experimental evidence. (Laforgue et al., 1988).

Oriented Time

1. From the universal reversible time, an additional breaking generates the oriented time, both in the astronomical and in the living matter.
2. Irreversibility for the environment. We refer to Prigogine and Stengers (1988).
3. Irreversibility for the living matter. We refer to Lochak (1986). Because equation (0), above discussed, is “microreversible” the second breaking could come from an additional term vanishing in the stationary states but increasing with time in evolutionary processes.
4. Negative times. Taking into account the fuzzy character of the time reversal symmetry, the third breaking cannot suppress completely the occurrence of negative times. Reversed time is controlled by direct time. Except in the three above reported cases, time reversal symmetry is not verified by the medium. Free motion of the particle following eg.(0) or of the vacancy following time reversal reciprocal equation takes place only during short jumps from an interaction site to an other. Fig. 2 schematizes the law of motion of the electric charge corresponding to the transport by proton or by proton vacancy in an unitary field (fluctuations are neglected). The reserved jumps are estimated in the range of 10^?12s. It is not excluded that such a jump can control a direct phenomenon.
5. The living time. Biological phenomenon appears as an oriented set of events. Nevertheless latency or exaltation phases could be perceived. This modulation could be described by positive and negative times additional to the basic time. (Negative can be interpreted as above.)

Living produces Time

1. That were not understandable, if time was only a frame, in which change occurs. Taking change as frame and time as effect, we regard biological activity as integrating reversible and irreversible time. Living synchronizes internal and external time by its own effort as it results (Lestienne, 1990) from Chronobiology.
2. Time modulation. Let us consider the dy₁...dy_i...dy_p changes in the variables of the system, dy={dy_i} has produced dt. We proof (eq.(1) to (4)) that time is modulated by a Φ_(y) speed coefficient depending on the medium. t_modulated=tΦ^-1 _(y)
3. The production of reversible time (e.g.acido-basicity) determines time modulation. As above reported it remains some reversibility effects (jumps of negative time) which modulate time. E.g., if an important amount of reagent is necessary to modify an acid-base equilibrium, Φ_(y) is small.
4. Time modulation and activation-repression reciprocity. As well-known, long t_modulated means repression, short t_modulated means exaltation. Extrema of ? are symmetrical because particle and vacancy are reciprocal. Nevertheless reciprocity is not perfect. E.g., on fig. 3, the wet receptor determines the cell increasing, the dry receptor the cell senescence of a certain alga (Lück, 1962).
5. Irreversible time production. Medium accepts entropy. Hence it acts in the second breaking of time. Living extracts the free energy from the medium, like a dissipative structure. That insures an operative point far from the thermodynamical equilibrium.

Consumption of Time

1. The three followings correspond to the more trivial time consumption.
2. Rhythmical time. Free energy flux is favourable to the arising of order in space or time. This later gives a structure to the living time.
3. Mutual dependence of reversible time and rhythms. Time irreversible structure can be controlled by the above considered particle-vacancy equilibrium. Consequently the living time (modulated and structured) is a chemical time connected to molecular properties and to statistical thermodynamics. Practically, the connection between chronobiology and chemistry is important. The use of drugs could be interpreted as a response to an aggression against biorhythms.
4. Lifetime. The dead-birth rhythm can be broken in two ways: evolution or indefinite life. This later is non exceptional for the living matter, e.g. in the vegetals where it is connected with the chlorophyllic assimilation; the time reversal significance of which is evident.
5. The plan of the alchemist. Indefinitely life has fascinated individuals. Do the human species becomes better adapted by a longer life?

Conclusions

1. Atoms of time could exist.
2. Biological time is defined by the breaking of five generalized symmetries, namely: Minkovski's space symmetry, reversibility, homogeneity, rhythmicity, generations reproduction.
3. Environment and medium determine non relativistic, oriented, structured time.
4. At the microphysical scale, a fuzzy time reversal symmetry takes place, the breaking of which is not complete. Reversible time and dominating irreversible time are integrated in living phenomena.
5. Three fundamental particle-vacancy reciprocities admit a part of reversibility. Irreversibility governs the all others phenomena.
6. Time is produced chemically.
7. A new perspective is the connection between chemical equilibria and rhythms including the time of the life.

     

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.

     

Semiaerobic induction of a nitrate reductase activity in growing cultures of Rhodopseudomonas capsulata E1F1 containing NH 4 + ions as nitrogen source

Rhodopseudomonas capsulata E₁F₁ growing under chemo- or photoorganotrophic conditions shows nitrate reductase activity which:

1. Is not repressed by ammonium ions;
2. Is governed by the partial pressure of oxygen in the gas phase.

Upon induction of nitrate reductase activity under optimum conditions, and also in the presence of amonium ions, subsequent addition of nitrate does not result in nitrite production. The specific activity of the enzyme increases by a factor of 10, when the growth medium is supplemented by the addition of nitrate. The physiological role of this ammonium resistant activity is not known.     

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.

     

The salt relations of marine and halophilic species of the unicellular green alga,Dunaliella

1. Comparisons were made of the effects of salt on the exponential growth rates of two unicellular algae,Dunaliella tertiolecta (marine) andDunaliella viridis (halophilic).
2. The algae contained glycerol in amounts which varied directly with the salt concentration of the growth media. The highest measured glycerol content ofD. tertiolecta was approximately equivalent to 1.4 molal and occurred in algae grown in 1.36 M sodium chloride. The highest glycerol content measured inD. viridis was approximately equivalent to 4.4 molal and occurred in algae grown in 4.25 M sodium chloride. Lower concentrations of free glucose, which varied inversely with extracellular salt concentration, were also detected.
3. It is inferred that Na⁺ is effectively excluded from the two algae. There was some evidence of a moderate uptake of K⁺.
4. Comparisons were made of erude preparations of the glucose-6-phosphate dehydrogenase and an NADP-specific glycerol dehydrogenase from each species and of the effects of salt and glycerol on the activities of these enzymes. It is concluded that the different salt tolerances of the two algae cannot be explained by generalized differences between their enzyme proteins.
5. Although intracellular glycerol must necessarily contribute to the osmotic status of the algae, its primary function in influencing their salt relations is considered to be that of a compatible solute, whereby glycerol maintains enzyme activity under conditions of high extracellular salt concentration and hence low (thermodynamic) water activity.

     

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.

     

Studien über die Testaceenbesiedlung der Seen und Tümpel des Abisko-Gebietes (Schwedisch-Lappland)

1. From 40 waters of the Abisko-district (Sweden, Lapland) 58 samples were collected (essentially samples from sediments).
2. It is not possible to clear the origin of all discovered tests of sediments. The bottom of most waters was covered with mosses, from which vegetation, tests can come into the sediments. But also tests from other biotopes, can be found at the bottom.
3. Nevertheless we can recognize typical characters of those species living in sediments. The prevalent type is the “Difflugia-type”. Those species of Centropyxis which immigrated into sediments demonstrate a trend towards the “Difflugia-type”. The immigration is possible from Aufwuchs, mosses and soils. 62,7% of the recorded tests belong to Difflugia, 17,8% to Centropyxis.
4. The prevalent species in the sediments of the Abisko-district is Difflugia elegans var. teres, the next is D. glubolosa.
5. A great number of investigated waters contained the oligotrophic species Centropyxis aërophila. Only one lake (Ruontenjaure) shows the association of dystrophic lakes.
6. Some species are described taxonomically, for instance: Centropyxis nauwercki n.sp. C. nauwercki is very much like Difflugia, but is also connected with C. platystoma. The new species shows a trend from Centropyxis to Difflugia.
7. C. aërophila can also immigrate into the Aufwuchs. There the species has membraneous tests.
8. Geographical aspects of the sediment colonization are discussed.

     

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.

     

Somatic embryogenesis and plant regeneration in garden leek

High frequency plant regeneration via somatic embryogenesis has been induced from in vitro shoot-base cultures of seedlings of garden leek (Allium porrum L.). Four main steps are involved in the procedure using BDS medium:

- shoot multiplication with 17.6 mM benzyladenine;

- induction of nodular callus from the in vitro shoot base with 9 mM 2,4-dichlorophenoxyacetic acid;

- initiation of embryogenic callus from nodular callus with 9 mM 2,4-dichlorophenoxyacetic acid +7.6 mM abscisic acid;

- plant regeneration from embryogenic callus with 9.8 mM N⁶-(2-isopentenyl)adenine.

The presence of 2,4-dichlorophenoxyacetic acid in the medium and light conditions were shown to be essential for nodular callus induction and somatic embryogenesis. Abscisic acid was not a prerequiste for somatic embryogenesis, but it significantly increased the frequency.