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 chemical identification of root promoters extracted from avocado tissues

From the Avocado Rooting Promoter (ARP) 4 compounds were isolated and identified as:

1. 1 acetoxy - 2,4 dihydroxy-n-heptadeca-16-en;
2. 1 acetoxy - 2,4 dihydroxy-n-heptadeca-16-yn;
3. 1,2,4 trihydroxy-n-heptadeca-16-en;
4. 1,2,4 trihydroxy-n-heptadeca-16-yn.

The rooting activity of the pure compounds was verified using the mung bean rooting bioassay. Compound 2II is the most active.     

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.

     

LCA in decision-making processes

Synthetic sulfuric acid is used in a wide range of applications in fine chemical industry. Despite an already performed optimization of input amounts, used sulfuric acid is still a quantitatively important waste by-product. As a result, different utilization technologies for used sulfuric acid exist:

1. production of gypsum
2. thermal reductive cracking
3. thermal cracking and oxidation

This makes an LCA study of this waste by-product quite interesting. In this paper:

? the starting point for a comparative LCA of the above mentioned utilization technologies at a concrete situation is explained, in a work of Ciba-Geigy Corp.

? a short summary of the comparative LCA is presented

? lessons learned from performing the LCA and using it in a decision process are described.

     

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.

     

Survival,osmoregulatory ability,and respiration of idotea chelipes (Crustacea,Isopoda) from lake veere in different salinities and temperatures

1. An ecological and physiological study ofI. chelipes from Lake Veere, The Netherlands, was made.
2. Both osmoregulatory capacity and survival decrease with increasing temperature as well as with decreasing salinity.
3. Respiration experiments suggest that the need of energy by osmoregulatory activity may be supplied at the cost of other physiological processes, at any rate at temperatures of 10°C and higher.
4. It may be expected that, if temperatures higher than 15°C and salinities lower than 8‰ coincide, the population ofI. chelipes will be affected negatively.

     

An analysis of amino acid composition of a few oxidoreductases by different methods

1. All methods used to analyze amino acid composition of different enzymes agree well with each other.
2. They lead to a relationship between amino acid composition and function of proteins.
3. Cytochrome oxidase is in a class by itself; copper-containing oxidases are closely related as expected.

     

Effects of prenatal cocaine exposure in the prefrontal cortex of the rat

This work was undertaken in order to assess the organization of the prelimbic area of the medial prefrontal cortex of rats exposed prenatally to cocaine. Pregnant Wistar rats were assigned to the following groups:

1. Cocaine—60 mg/kg body wt/d sc, from gestational days 8–22; 0131
2. Saline;
3. Pair-fed; and
4. Nonmanipulated.

Male offspring were perfused on postnatal days 14 and 30. Six brains per group and per age were embedded in celloidin to calculate the volumes of the prelimbic area; sections from the other six brains were embedded in resin and processed for electron microscopy. Using semithin sections (2 μm) of layers II–III and V–VI, the following parameters were calculated:

1. The fraction of the neuropil occupied by neurons (V_V);
2. The packing (N_A) density; and
3. The numerical (N_V) density.

Qualitative alterations consisted of dispersed profiles of degenerated neurons and dendrites in the medial prefrontal cortex. No significant differences were found in the gross morphometric parameters when the cocaine group was compared with the other groups. A high interanimal variation was shown in the prelimbic volumes of postnatal day (PND) 14 cocaine-treated rats, and a decrease in volumes was detected at PND30. Although there are some alterations in the main afferent cortical target area for dopaminergic input, its gross morphometric parameters do not seem to be sufficiently affected to account for the behavioral alterations referred to as being dependent on this brain region.     

Acetylcholinesterase kinetics

Three mechanisms have been suggested to describe the inhibition of acetylcholinesterase (EC. 3.1.1.7) by an excess of acetylcholine.

1. Substrate inhibition occurs through the reaction of acetylcholine with acetylated enzyme. The deacetylation of this ternary complex is supposed to be completely inhibited.
2. A ternary complex is formed as in (i). However, the deacetylation is not completely inhibited.
3. A two-site-mechanism is discussed. Acetylcholine binds either to the active site or to the modifier site. Binding to the latter changes the activity of the active site.

Steady state treatment was applied to (i)–(iii). A least squares fit led to catalytic parameters. It is demonstrated that mechanism (ii) is the most simple one which can describe satisfactorily the experimental data. Limits for a set of rate constants are derived from the catalytic parameters. A numerical integration shows that the steady state approximation may be used even when the mechanisms are rather complex.     

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.

     

Vocalizatons of chimpanzees in non-caged captivity

1. The chimpanzee vocal system is an emotionally linked vocal response developed on a standard pre-symbolic primate system.
2. Differences in number of sounds recorded by different observers may be due to personal choice, or due actual presence or absence of certain sound types in different living situations. Further research is needed in this case before comparisons can be made.
3. Idiosyncratic use of certain signals may serve as a basis for growth of local dialects in different areas. Spread of such dialects may be related to the amount of respect accorded to dominant animals. More study may shed light on the growth and development of pre-symbolic systems.

     

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.

     

Erecteur a dépression (Vacuum erection device): Mise au point

The vacuum erection device (VED) is a nonsurgical alternative for the treatment of erectile dysfunction. This method is based on 2 phenomena:

1. an erection-like state occurs when the penis is placed in a vacuum
2. this state can be maintained by a constricting band placed around the base of the penis

The erection-like state thus obtained differs from a normal erection in the following ways:

1. blood flow into the penis decreases
2. penile skin temperature falls
3. congestion of extra-corporeal penile tissues occurs
4. the penis pivots at its base
5. the ejaculate is trapped in the proximal urethra

About 30 to 60% of men who trie the device at home purchase it for continued use. The others are unable to achieve sufficient rigidity, experience side-effects or dislike the use of the device despite good result. About 60 to 80% of the men who purchased the device continue to use it regulary at short or middle term. The VED seems to have lesser drop-out rate than the self injection therapy. The most frequently encountered side-effects of the device are pain, petechiaes, bruising and ecchymosis.     

Numerical integration of a stochastic model for the Volterra-Lotka reaction

Time-integration of the master equation governing the birth-and-death model of the Volterra-Lotka reaction is carried out for three different initial conditions, with the results:

1. Fluctuations destroy the deterministic steady state in a manner quantitatively predicted from a cumulant expansion;
2. The sustained oscillatory behavior predicted by the deterministic model degenerated after 1/4 cycle in the stochastic model;
3. It is possible to select initial distributions such that the asymptotic distribution is a spike at the origin of the plane of reactants.

     

Anaerobic respiration in latex ofHevea brasiliensis substrate and limiting factors

The site of anaerobic respiration in the latex is the serum. The main respiratory substrate is fructose. The CO₂ formation in serum is increased by additional fructose on the average about 2.5–3 times. Glucose does not influence CO₂ evolution by serum but slightly increases O₂ consumption. With respect to sugars, latex serum contains essentially only sucrose and a low amount of raffinose. During the incubation of serum sucrose is hydrolysed, the fructose component is immediately utilized in respiration and glucose accumulates. The rate of CO₂ formation in latex as influenced by fructose is negatively related to the rubber content of the latex. Latex with a high rubber content reacts only slightly or not at all on additional fructose. The main limiting factors of latex respiration and sugar utilization are the following:

1. The deficiency of substrate, due to low activity of β-fructofuranosidase.
2. The rate of glucose phosphorylation (D'Auzac, Jacob 1967).
3. Presumably the low activity of phosphoglucoisomerase.
4. The rubber content of the latex.
5. The concentration of CO₂ in latex; this factor may be important in vivo, in the laticiferous system.

     

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.

     

Age-at-death diagnosis and age-at-death distribution estimate: Two different problems with many aspects in common

A quantitative or qualitative trait detected on human skeletons can be used to solve two inferential problems:

1. Diagnosing age-at-death
2. Estimating age-at-death distribution in the human community which the skeletons belong to.

The Bayesian solutions of A) and B) are rather different and we think useful an accurate discussion about that subject.     

ATP-driven succinate oxidation in the catabolism of Desulfuromonas acetoxidans

The oxidation of succinate with elemental sulphur in Desulfuromonas acetoxidans was investigated using a membrane preparation of this bacterium. The following results were obtained:

1. The preparation catalyzed the oxidation of succinate with sulphur and NAD. These reactions were dependent on ATP and were abolished by the presence of protonophores or dicyclohexylcarbodiimide (DCCD).
2. The membrane preparation also catalyzed the reduction of fumarate with H₂S or with NADH. These activities were not dependent on ATP and were not affected by protonophores or DCCD.
3. By extraction-reincorporation experiments it could be shown that menaquinone is involved in electron transport between H₂S and fumarate and between NADH and fumarate.
4. The membrane fraction catalyzed the reduction of the water-soluble menaquinone-analogue dimethylnaphthoquinone (DMN) by succinate, H₂S, or NADH, and the oxidation of DMNH₂ by fumarate. These activities were not dependent on the presence of menaquinone and were not influenced by ATP.
5. The activities involving succinate oxidation or fumarate reduction were similarly sensitive to 2(n-nonyl)-4-hydroxyquinoline-N-oxide, while H₂S and NADH oxidation by DMN were not affected by the inhibitor.

It is concluded that the catabolism of D. acetoxidans involves the energy-driven oxidation of succinate with elemental sulphur or NAD as electron acceptors and that menaquinone is a component of the electron transport chain catalyzing these reactions.     

The role of microorganisms in mobilization and fixation of phosphorus in sediments

Cycling of phosphorus (P) at the sediment/water interface is generally considered to be an abiotic process. Sediment bacteria are assumed to play only an indirect role by accelerating the transfer of electron from electron donors to electron acceptors, thus providing the necessary conditions for redox-and pH-dependent, abiotic sorption/desorption or precipitation/dissolution reactions. Results summarized in this review suggest that

1. in eutrophic lakes, sediment bacteria contain as much P as settles with organic detritus during one year
2. in oligotrophic lakes, P incorporated in benthic bacterial biomass may exceed the yearly deposition of bioavailable P several times
3. storage and release of P by sediment bacteria are redox-dependent processes
4. an appreciable amount of P buried in the sediment is associated with the organic fraction
5. sediment bacteria not only regenerate PO₄, they also contribute to the production of refractory, organic P compounds, and
6. in oligotrophic lakes, a larger fraction of the P settled with organic detritus is converted to refractory organic compounds by benthic microorganisms than in eutrophic lakes.

From this we conclude that benthic bacteria do more than just mineralize organic P compounds. Especially in oligotrophic lakes, they also may regulate the flux of P across the sediment/water interface and contribute to its terminal burial by the production of refractory organic P compounds.     

Habitability of the early earth: Clues from the physiology of nitrogen fixation and photosynthesis

In the absence of direct evidence concerning the nature of the early Earth environments, it is acceptable under the uniformitarian principle to attempt to define primitive habitats from modern procaryotic physiology. Combining the rock and fossil record with present phylogenetic reconstuctions, application of this paleoecological approach to the evolutionary biochemistry and physiology of nitrogen fixation and photosynthesis leads to several inferences about the nature of Archean environments:

1. To stimulate nitrogenase evolution and avoid its repression, the activity of the NH ₄ ⁺ ion was less than 10^?3, and probably lower.
2. To be consistent with a moderately protective ozone screen, while not also repressing nitrogenase activity, incursions of abiotic dissolved oxygen at levels in the range 10^?1.2?10^?3.5 PAL would have been acceptable.
3. To induce the formation and activity of RuBP carboxylase, the pCO₂ was less than 100 PAL.
4. To support Photosystem I activity, sulfide concentrations of at least 10^?4 M were present in the photic zone.
5. To avoid a too-rapid oxidation of sulfide, the pH was probably between 6–7, where H₂S exceeds HS^?.

Evolutionary ‘pressure’ to stimulate the later development of oxygenic photosynthesis (Photosystem II), would require several subsequent habitat modifications:

1. Lowering the sulfide to < 10^?4 M to inhibit Photosystem I.
2. Raising the pH above neutral (HS^? > H₂S), to mediate more rapid oxidation of HS^?.
3. Maintaining either an illumination below 300–400 lux (to avoid photosynthetic O₂ self-repression of nitrogen fixation), or an adequate local source of combined nitrogen (aNH ₄ ⁺ > 10^?4) to repress nitrogen fixation entirely.