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.

     

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.

     

Brisures de symetrie hierarchisant les niveaux d'organisation

1. The sequence of the organisation levels is regarded as originating from a sequence of symmetry breakings. Each breaking generates a more improbable structure. In addition to the Euclidian symmetries, homogeneity, isotropy, translation, rotation, helix displacement, neutrality and even indiscernibility can be broken. Here are considered the initial (§ 2) and the subatomic breaking molecular morphogenesis (§ 3, 4) and other higher breakings.2.1 HOMOGENEITY BREAKING OF THE VACUUM SPACE. We studied this as a new model of wave-corpuscle relation. Every noticeable point breaks the space homogeneity. Directed by a momentum this breaking operates as a fissure.2. Postulate of the corpuscle. The quantum mechanical corpuscle is the end of a fissure, the momentum of which characterises direction and velocity.2.2. Postulate of the wave. The associate wave comes from the end of the fissure and works to split the medium.2.3. Corollary to the trajectory. The fissure prefers continuity and a straight line. Nevertheless the fissure can stop at a point and then start from an other point. This discontinuity and any momentum possible discontinuity are limited only by uncertainty relationships; frequency of discontinuity is limited by the first one. Vacuum has no memory of the fissures. 2.4.Corollary to the localisation. The fissure diminishes the medium constraints and allows the medium to vibrate in a domain surrounding the end of the fissure.2.5. Physical analogies.

- Photo-elastic studies of the fissuration of solids (Corten & Park, 1963) show a little sphere and a wavelike perturbation at the end of the fissure.

- A fragile and resonating object can be broken by a sound wave. This crack emits a sound wave. Here we consider one associated wave, emitted and absorbed.

- Broken panes picture an emission of rays.

li]2.6. Consequences of the fissure model (without modifying the laws of quantum mechanics).

1. The corpuscle generates a fractal trajectory. From literature (Abott & Wise, 1981; Nelson, 1966) or from the present model we can calculate a fractal dimension, namely 2. But this numerical value corresponds to the simplest assumptions. Inhomogeneity or rapid changes in time could increase this value. The actual fractal dimension is a physical property which was neglected until now. It can govern the probability of collision between corpuscles, hence the probability of nuclear fusion between corpuscles, like deuton, the enhancement of which at low energies was recently discovered (Fleischman & Pons 1989).
2. The difficulties linked with the extrapolation from macroscopic structure vanish. No wave is indefinitely extended. Corpuscle can disappear and reappear again (e.g. it can pass through a nodal surface). The indiscernibility is included in the model.

li]3. ATOM HYBRIDIZATION. The calculated value of the entropy (Chantelot & Laforgue, 1966) demonstrates that the hybridization is a physical phenomenon. It corresponds to the breaking of the spherical symmetry into a polyhedral symmetry. Hybridized orbitals can be a priori determined by equiprobability of the different angular momenta for the atom (which cannot be measured into a molecule). The independently determined eigenfunction enables one to find the same symmetry. li]3.1. Image of the molecule on the basis of a constituent atom. The “natural orbitals” of the molecular wave function of such a basis describe pertinently the atom symmetry breaking and the supplementary deformation by the molecular surrounding. li]3.2. The criterion of the so-called “maximum ponderated overlapping” leads to the “image orbitals”. Hence we obtain a generalization of the well known criterion of Pauling. li]3.3. Physical sense of the “image orbitals”. They describe the molecule from the point of view of the atom. They are adapted to the bonding of the atom with its molecular surrounding. li]4. THE CHIRAL BREAKNG. Referring to previous publications (Laforgue, 1983, 1988, 1989a, b, c, d, 1990) asymmetrical molecules oscillate or break depending on the height of inversion and destruction barriers. Fig. 1 pictures the domains of stability. Fig. 2 pictures the so-called “Path of Easiest Destruction and Inversion”. li]4.1. Equations of the chiral breaking. The more general case is the endothermic one (Fig. 3). Some equations are proposed. The so-called destruction time {Eq A} and inversion time {Eq B} determine by {Eq Z} process the final symmetry {Eq C} or final chirality {Eq D}. A more accurate treatment is the application of the Bohr-Heisenberg principle. If the inversion barrier is higher than the destructive one, the classical solution is confined to the right or to the left; hence the quantum behaviour is a random tunnelling and not a periodical oscillation (at low quantum numbers the amount of inversion is negligible). The results are experimentally verified because no evolution in chiral structure other than random inversion was ever observed. li]4.2. Chiral molecule is a pseudo-stationary state. Two enantiomers are distinct molecules. They do not have the symmetry of the Hamiltonian because they are not a solution of the Schrödinger's amplitude equation. li]4.3. Chiral constraint. The complete error potential is formulated. It follows an electronic oscillation and intra-molecular forces on the nuclei. In an oscillating molecule these forces affect the oscillation. The forces become permanent by chiral breaking, which explains asymmetrical properties. li]4.4. Chiral medium. A molecule submitted to asymmetrical forces has asymmetrical properties. Some of these effects have not yet been formulated but should be postulated (e.g. induced electronic circular dichroïsm). Quantum measurement theory shows that the effective inversion time increases when chiral interactions become more frequent. li]4.5. Biological role of chirality. Racemic life cannot work, hence there is optical symmetry breaking of the biosphere. It demands an initial preference and global autocatalysis, which can take the form of molecular recognition followed by defense mechanisms. The set of chiral molecules can be characterised as an intermediate level between matter and life. li]5. BREAKING OF THE CHIRAL LEVEL AND OF THE HIGHER ONES.

- The chain of identical chiral monomers can be submitted to an helix displacement breaking (i.e. non identical monomers) leading to a memory organisation level.

- If the electronic fluctuation through chemical bounding is broken, two systems of electrons become mutually discernable. That occurs on the organisation level of the super molecule.

- Following breakings generate spacial forms and acting mechanisms, as well known.

li]6. CONCLUSION. The reviewed breakings can be interpreted in terms of living requirements. There common cause is symmetry fragility. Matter and life derive from the vacuum space by successive spontaneous symmetry breakings. Finally, the question of an upper limit of organisation arises.     

Growth of Nitrobacter in the presence of organic matter

1. Culture filtrates of heterotrophic bacteria were tested for their stimulatory effect on nitrification of three strains of Nitrobacter.
2. Yeast extract-peptone solution, in which Pseudomonas fluorescens had grown, after removal of the cells was added to autotrophically growing cultures of Nitrobacter agilis; it caused a stimulated nitrite oxidation and growth of Nitrobacter agilis.
3. The degree of stimulation depended on: a) the proportion of the culture filtrate to the autotrophic medium; b) the composition of the complex medium in which Pseudomonas fluorescens had been grown; c) the time the heterotrophic bacterium had been grown in the complex medium.
4. The stimulatory effect was highest with Nitrobacter agilis, less with Nitrobacter winogradskyi and negligible with Nitrobacter K ₄.
5. It was possible to adapt nitrifying cells of Nitrobacter agilis to higher concentrations of yeast extract and peptone. After the nitrite had been completely oxidized the cell-N still increased up to 30% before growth stopped.

     

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.

     

A study of the relationship between mechanical characteristics and the coastal vegetation among several broad-leaf trees in Miura Peninsula in Japan

The mechanical properties of broad-leaf tree species in a maritime-wind exposed habitat in central Japan were examined. The broad-leaf trees studied were Celtis sinensis var. japonica, Ilex integra, Eurya japonica, Pittosporum tobira, Euonymus japonicus and Cinnamomum japonicum. The results obtained can be summarized briefly as follows:

1. At places with weaker wind, the number of species increased and the height of the canopy increased.
2. The fracture strength σ_m showed no dependence on tree part or branch thickness, but was constant.
3. The order of strength was Celtis sinensis var. japonica > Ilex integra > Eurya japonica > Pittosporum tobira > Euonymus japonicus > Cinnamomum japonicum, and these six species could best adapt to the wind pressure in the study area.
4. Within species, fracture strength varied directly with wind strength.
5. The strain ε_m decreased as the trunk became thicker.
6. Within species, strain energy U_m varied directly with wind strength.

     

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.     

Changes in cell composition and viability of Bdellovibrio bacteriovorus during starvation

1. Washed cell suspensions of Bdellovibrio bacteriovorus harvested shortly after lysis of their substrate organisms and shaken in buffer have a constant and high endogenous respiration rate for a bout 6 h which then declines sharply to a rate approximately 10% of the original. Viability of cell suspensions shows little change over the first 4–6 h and then decreases by some 50% in 10 h.
2. Over the first 5–6 h of starvation there is a loss of about 50% of total cell carbon. This loss is distributed about equally between CO₂ and small molecules released into the suspending buffer. The protein and nucleic acid contents of the cells decrease concomitantly from time zero during starvation while DNA content remains constant. Ribosomal profiles show a rapid degradation of ribosomes.
3. In the presence of glutamate or glutamate plus a balanced amino acid mixture, loss of cell material and loss of viability is partially or completely prevented. There is extensive protein turnover when glutamate and an amino acid mixture are available to the bdellovibrio.
4. The pattern of changes observed in B. bacteriovorus during starvation is compared to reported changes in other species of bacteria, and the significances of its high endogenous respiration and sensitivity to starvation are discussed.

     

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.

     

The distribution ofActinocyclus normanii (Bacillariophyceae) in estuaries: Field observations and laboratory investigations

Combining the results of field observations from the Eider, Elbe, Weser and Ems estuaries and laboratory experiments it was found that:

1. in German North Sea estuaries the tidal freshwater reaches are the main habitat of the diatomActinocyclus normanii.
2. the residence time within the tidal freshwater reaches is a key factor controlling not only seasonal and spatial densities within one estuary, but also density differences between estuaries;
3. A. normanii is well adapted to strongly changing light situations and thus adapted to estuaries with high vertical turbulent mixing and low values of Zeu/Zmix;
4. the downstream limit of the habitat ofA. normanii is mainly determined by light limitation rather than by hyperosmotic stress.

     

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.

     

Reverse electron flow in chloroplasts

Energy dependent reverse electron flow reactions in isolated thylakoids provide a unique tool to study, in the dark, the coupling between the ATP synthase, proton transport and the electron transfer system. Appropriate experimental conditions have been established to follow experimentally the following reactions:

1. ATP driven proton uptake into the inner-thylakoid space, which requires preactivation of the ATP synthase.
2. ATP driven reverse electron transport, which involves proton transport as an intermediate, and results in the reduction of Q_A by an externally added electron donor.
3. ATP driven luminescence, which requires the presence of an oxidized partner on the water side of photosystem II, and involves electron transport from Q_B to Q_A.
4. ΔpH driven reverse electron flow, which does not require the participation of the ATP synthase, and uses reduced intermediates between the two photosystems as electron donors for the reduction of Q_A.
5. ΔpH driven luminescence which again uses reduced intermdiates between the two photosystems as electron donors for Q_A reduction, and requires the presence of an oxidized partner on the water side of photosystem II.

Several of these reactions have been shown to occur in intact chloroplasts and may provide an important regulatory mechanism in vivo.     

Growth of a floating aquatic weed,Salvinia under standard conditions

1. Growth of the floating aquatic weed, Salvinia, in sterile culture was exponential for at least 2 weeks under standardized conditions.
2. Increase in light intensity or in CO₂ resulted in increases in growth rate, but did not extend the exponential period of growth.
3. This aquatic plant, like many others, discriminates against calcium relative to strontium.
4. In culture Salvinia exhibited luxury consumption of N and P.
5. Because of high C/N ratios, Salvinia may not be a favorable source of animal food, but might be useful in nutrient removal schemes.
6. In sterile culture, S. molesta produced fewer leaves than S. minima, but maintained a significant increase in leaf area and dry weight. This may be correlated with the ability of the first species to rapidly spread over tropical waterways.

     

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.

     

On the mechanism and possible therapeutic application of delayed adaptation of the heart to stress situations

Mild (not harmful) stress may initiate anadaptive mechanism, protecting the heart from harmful consequences of a more severe stress. There are at least three known types of cardiac adaptation to stress such as:

1. the gradually developing long lasting adaptation to chronic mechanical overload, leading to cardiac hypertrophy, later to cardiomyopathy and heart failure,
2. the rapidly developing adaptation to moderate stress initiated by ‘preconditioning’ brief coronary occlusion(s) or brief periods of rapid cardiac pacing, protecting for less than 1 h against consequences of a subsequent, severe stress,
3. the later appearing, more prolonged cardio-protective adaptation, described by us in 1983, induced by various forms of more severe but not injurious stimuli, such as an optimal dose of prostacyclin or its stable analogues; or a series of brief periods of rapid pacings.

This form of cardiac adaptation to stress protects for 24–48 h against consequences of a more severe stress such as:

1. myocardial ischaemia;
2. early and late postocclusion and reperfusion arrhythmias;
3. early morphologic changes secondary to ischaemia and reperfusion;
4. ischaemia induced myocadial loss of K⁺ and accumulation of Na⁺ and Ca⁺⁺;
5. it may increase the tolerance to the toxic effects of cardiac glycosides.

A reduced response to beta-adrenergic stimuli and a concomitant increase in activity and amount of PDE I and IV was shown by us earlier. The hypothesis that these factors may play a role in the mechanism of delayed protection was confirmed by our present findings according to which 7-oxo-PgI₂-treatment greatly attenuated the dose dependent isoprenaline-induced increase in contractility, relaxation and myocardial cAMP level in rat hearts isolated 48h after 7-oxo-PgI₂. In addition all these values are in close correlation with each other. The endogenous ‘self-defence’ of the heart based on adaptation represents anew therapeutic concept, different from the classical drug-receptor interaction produced protection. Its possible exploitation to therapeutic use requires that the adaptation inducing stress should beapplicable topatients, furthermore prolongation of duration of protection should be possible. As a first step in testing applicability to therapy we had to show that drug induced adaptive protection is existing in the conscious animal. In our present study we found an attenuation of rapid pacing induced elevation of the ST-segment in the endocardial electrogram and in the left ventricular end diastolic pressure in conscious rabbits 24–48 h after treatment with Iloprost. Besides we found an attenuation of tachycardia and arrhythmias due to two stage coronary artery ligation in conscious dog 48 h after pretreatment with 7-oxo-PgI₂. Finally we were able to demonstrate that protection against coronary artery occlusion-induced ST segment elevation and arrhythmias can be prolonged at will by periodically repeated maintenance doses.     

Tres adiciones al genero Baccharis (Compositae) en Mexico

1. -Bigelowia pyramidata Rob. & Greenm. from Oaxaca proves to be a dioecious plant and is therefore transferred to the genusBaccharis.
2. -Baccharis matudae sp. nov. is described on the basis of material collected in Zacatecas and San Luis Potosí. The species is closely related toB. pyramidata (Rob. & Greenm.) Rzedowski.
3. -Baccharis zamoranensis sp. nov. is described on the basis of material collected on the border of Querétaro and Guanajuato. The taxon is related toB. multiflora H.B.K., known from central and southern Mexico.

     

EPR characterization of oxide supported transition metal ions: Relevance to catalysis

EPR spectroscopy is a powerful tool to identify at a molecular level, the different steps of catalyst preparation, and of catalytic reactions:

1. Deposition of paramagnetic transition metal ions onto a support is monitored, and the coordination sphere of the metallic center is characterized by EPR.
2. The catalyst is also characterized after activation (thermal oxidation or reduction):

- the distribution among the different sites in zeolites can be determined;

- the dispersion of the active phase may be appreciated;

- the unsaturation degree of the active site may be evaluated using probe molecules such as water or¹³C enriched carbon monoxide.

1. The catalytic mechanisms can be investigated by studying the elementary steps of the catalytic reaction, as illustrated for methanol oxidation over Mo/SiO₂ catalysts whose EPR results have extended the reaction mechanism proposed on the basis of kinetic data. In addition, reaction intermediates may be isolated inquasi-in situ conditions as in the case of olefin oligomerization catalyzed by Ni/SiO₂ systems.

     

Coordination of energy and carbon metabolism in lysine producing Brevibacterium strains

The present paper deals with the coordination of energy metabolism, glucose consumption rate, glycolytic and TCA cycle enzyme activities in the lysine-producing bacterium Brevibacterium flavum. It is shown, that inhibition of the elctron transport chain causes changes of the following sequence:

at first, TCA cycle enzymes are activated;

secondly, TCA cycle enzyme activity decreases, and glycolytic enzyme activities as well as glucose transport rate increase; there is a slight increase in Q_o2 and a considerable one of O₂ consumption in cyanide-resistant respiration pathway;

thirdly, TCA cycle enzyme activities and glucose transport rate decrease.

It is supposed, that coordination of carbon and energy metabolism in B. flavum depends on intracellular ATP concentration or energy charge value.     

Biosynthetic pathways of Vibrio succinogenes growing with fumarate as terminal electron acceptor and sole carbon source

1. With fumarate as the terminal electron acceptor and either H₂ or formate as donor, Vibrio succinogenes could grow anaerobically in a mineral medium using fumarate as the sole carbon source. Both the growth rate and the cell yield were increased when glutamate was also present in the medium.
2. Glutamate was incorporated only into the amino acids of the glutamate family (glutamate, glutamine, proline and arginine) of the protein. The residual cell constituents were synthesized from fumarate.
3. Pyruvate and phosphoenolpyruvate, as the central intermediates of most of the cell constituents, were formed through the action of malic enzyme and phosphoenolpyruvate synthetase. Fructose-1,6-bisphosphate aldolase was present in the bacterium suggesting that this enzyme is involved in carbohydrate synthesis.
4. In the absence of added glutamate the amino acids of the glutamate family were synthesized from fumarate via citrate. The enzymes involved in glutamate synthesis were present.
5. During growth in the presence of glutamate, net reducing equivalents were needed for cell synthesis. Glutamate and not H₂ or formate was used as the source of these reducing equivalents. For this purpose part of the glutamate was oxidized to yield succinate and CO₂.
6. The α-ketoglutarate dehydrogenase involved in this reaction was found to use ferredoxin as the electron acceptor. The ferredoxin of the bacterium was reoxidized by means of a NADP-ferredoxin oxidoreductase. Enzymes catalyzing the reduction of NAD, NADP or ferredoxin by H₂ or formate were not detected in the bacterium.