Quantitative aspects of glucose metabolism by Escherichia coli B/r,grown in the presence of pyrroloquinoline quinone

Escherichia coli B/r was grown in chemostat cultures under various limitations with glucose as carbon source. Since E. coli only synthesized the glucose dehydrogenase (GDH) apo-enzyme and not the appropriate cofactor, pyrroloquinoline quinone (PQQ), no gluconate production could be observed. However, when cell-saturating amounts of PQQ (nmol to mol range) were pulsed into steady state glucose-excess cultures of E. coli, the organisms responded with an instantaneous formation of gluconate and an increased oxygen consumption rate. This showed that reconstitution of GDH in situ was possible.Hence, in order to examine the influence on glucose metabolism of an active GDH, E. coli was grown aerobically in chemostat cultures under various limitations in the presence of PQQ. It was found that the presence of PQQ indeed had a sizable effect: at pH 5.5 under phosphate- or sulphate- limited conditions more than 60% of the glucose consumed was converted to gluconate, which resulted in steady state gluconate concentrations up to 80 mmol/l. The specific rate of gluconate production (0.3–7.6 mmol·h^-1·(g dry wt cells)^-1) was dependent on the growth rate and the nature of the limitation. The production rate of other overflow metabolites such as acetate, pyruvate, and 2-oxoglutarate, was only slightly altered in the presence of PQQ. The fact that the cells were now able to use an active GDH apparently did not affect apo-enzyme synthesis.Abbreviations HEPES N-2-hydroxy-ethylpiperazine-N-2-ethane sulphonic acid - MES 2-morpholinoethane sulphonic acid - PQQ pyrroloquinoline quinone (systematic name: 2,7,9-tricarboxy-1H-pyrrolo-(2,3-f)-quinoline-4,5-dione) - WB Wurster's Blue (systematic name: 1,4-bis-(dimethylamino)-benzene perchlorate     

Evolution of Volatile Sulfur Compounds during Laboratory-Scale Incubations and Indoor Preparation of Compost Used as a Substrate in Mushroom Cultivation

Volatile sulfur compounds are known to be produced during the preparation of compost used as a substrate in mushroom cultivation. Because they cause odor problems, attempts have been made to reduce the production of these compounds. The influences of temperature and various additions on the production of volatile sulfur compounds from composting material were tested on laboratory-scale preparations. The production of H₂S, COS, CH₃SH, and (CH₃)₂S was proven to be a biological process with an optimal temperature that coincides with the optimal temperature for biological activity. The formation of CS₂ and (CH₃)₂S₂ was shown to be a nonbiological process. The emission of volatile sulfur compounds during the indoor preparation of mushroom compost appeared to be remarkably reduced (about 90%) as compared with the emission during the conventional outdoor process. Introduction of this indoor composting process would result in a significant reduction in environmental pollution.     

Behavioral evaluation of exhibit modifications designed to accommodate an aged diana monkey

Modifications in a zoo exhibit were made to increase the arboreality of an aged female diana monkey, and to increase her use of the central portion of the exhibit where a new food shelf had been added. Branches, which formed ramps to this shelf, also were added. Following these changes, the aged female's arboreality increased slightly, and her use of the central portion of the exhibit increased significantly. Changes in habitat use following these modifications also were noted in the other two diana monkeys in the group. These results suggest that zoo habitats can be made more usable for individuals whose behavioral capabilities might be limited due to age or physical disability.     

Neue Aspekte zur zugzeitlichen Frugivorie der Gartengrasmücke (Sylvia borin)

Zusammenfassung Freilandbeobachtungen und frühere Laboruntersuchungen (Berthold 1976) führten bisher zu einer widersprüchlichen Bewertung der zugzeitlichen Frugivorie bei der Gartengrasmücke. Deshalb wurden das Wahlverhalten gegenüber verschiedenen Beeren und Früchten in deren natürlichem Gehänge in einer Voliere geprüft sowie die Auswirkung unterschiedlich frugivorer Ernährung auf Körpermasse und tägliche Nahrungsaufnahme unter kontrollierten Laborbedingungen untersucht. Zwischen dem Präferenzverhalten gegenüber bestimmten Beeren und Früchten und deren Profitabilität bzw. Nährstoffgehalt bestand kein eindeutiger Zusammenhang. Demnach ist die Wahl zwischen verschiedenen Vegetabilien nicht einfach abhängig von ihrer Größe oder dem Nährstoffgehalt. Erhebliche Unterschiede zwischen den getesteten Beeren und Früchten zeigten sich bei der täglichen Aufnahmerate und den Auswirkungen auf die Körpermasse. Während bestimmte Beeren nur als Zusatzfutter zu einem immer, wenn auch geringfügig notwendigen, animalischen Standardfutter verabreicht werden konnten, waren die Gartengrasmücken mit Schwarzem Holunder und Feige auch bei ausschließlicher Gabe nicht nur in der Lage, ihre Körpermasse zu halten, sondern konnten dabei sogar normale Fettdeposition vollziehen. Offensichtlich sind bestimmte Vegetabilien für die Gartengrasmücke wesentlich bedeutsamer als bisher angenommen. Die Ergebnisse stimmen somit mit Beobachtungen aus dem Freiland überein. Die beobachteten qualitativen Unterschiede zwischen den Früchten und deren Wirkung auf die Körpermasse der Versuchsvögel ließen sich nicht allein mit dem Nährstoffgehalt der Beeren erklären. Vermutlich spielen die spezifische Qualität der Nährstoffe (z. B. Fettsäurezusammensetzung) und möglicherweise auch sekundäre Pflanzenstoffe eine wichtige Rolle.

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The significance of seasonal frugivory in migratory Garden WarblersSylvia borin

Summary In contrast to field observation, exhibiting an important role of seasonal frugivory,Berthold (1976) concluded that fruits are only a supplementary food, and he rejected the hypothesis that songbirds shift to a fruit diet during migration in order to render or to accelerate fat deposition.We investigated the preference of Garden Warblers upon various berries and pulpy fruits in an outdoor aviary. Furthermore, the effects of frugivory on body mass and food intake is measured in caged specimens under controlled laboratory conditions.In almost all feeding trials a significant selection between the two alternative fruit diets are obvious. However, no clearcut relationship between profitability or nutritive content of the various fruits and food choice is evident.In the experiments under controlled laboratory conditions the effects of varying extends of frugivory on body mass and food intake of captive Garden Warblers reveal a considerable difference between various berries and fruits. In some berries, the birds were not able to compensate for a reduction of the standard animal food by increasing frugivory. With Black Elder berries or figs, however, they did not only compensate for to maintain body mass rather they were able to gain mass during migratory fat deposition, even kept on an exclusive fruit diet.These results clearly exhibit a significant role of fruit diets in migrating Garden Warblers, with particular regards to Black Elder berries and figs, respectively.The observed differences between the various fruit diets do not correspond to the crude nutritive content of the pulp. Presumably, the specific quality of nutrients (for instance, fatty acid composition) or even secondary plant compounds have to be considered.The experimental results agree with field observations, indicating the importance of frugivory for the Garden Warbler, and they contradict Berthold's suggestion that fruits are only a least important supplementary food to an always necessary animal food.

     

Neutrophil hyperpolarization in response to a chemotactic peptide

The chemotactic peptide formylmethionyl-leucyl-phenylalanine (fMLP), at concentrations below 10(-9) M, elicits a sustained increase in the human neutrophil's membrane potential within 10 s of its addition. This hyperpolarization, detected with the fluorescent cationic potentiometric probes, 3,3'-dipentyloxacarbocyanine (diO-C5-(3)), and 1,1'-dipropyl-3,3,3',3'-tetramethylindocarbocyanine iodide (diI-C3-(3)), and with the anionic probe bis-(1,3-diethylthiobarbituric)trimethine oxonol (bis-oxonol), is immediately followed by a large depolarization when [fMLP] greater than 10(-9) M. By extracellular substitution of sodium ions with potassium ions or choline or by pretreatment of the cells with ionophores, we report here that the hyperpolarization is primarily dependent on an intact potassium ion gradient and is accompanied by a concurrent acidification of the cytoplasm (approximately 0.05 pH unit) Although the latter occurs simultaneously with a large, transient increase in cytosolic Ca2+ at [fMLP] greater than 10(-10) M, it occurs without a detectable increase in cytosolic Ca2+ at [fMLP] less than 10(-10) M. The hyperpolarization is neither affected nor initiated by the chemotactic peptide antagonist tert-butyloxycarbonyl-methionyl-leucyl-phenylalanine, whereas the depolarization is completely inhibited. Neutrophils isolated from patients with X-linked chronic granulomatous disease exhibit normal hyperpolarizations and cytosolic Ca2+ increases in response to chemotactic peptides but exhibit no depolarization or oxidative burst. The hyperpolarization appears earlier in the ontogeny of differentiating myeloid precursor cells than either the rise in cytosolic Ca2+ or the depolarization response. Together, these findings indicate that an increase in transmembrane potential is one of the earliest events in the neutrophil response to chemotactic peptides, coinciding temporally with increases in cytoplasmic Ca2+ and H+ concentrations but preceding detectable oxidative burst activity.     

Inhibition of [3H]Diazepam and [3H]3-Carboethoxy-β-Carboline Binding by Irazepine: Evidence for Multiple "Domains" of the Benzodiazepine Receptor

The binding of [3H]diazepam and [3H]3-carboethoxy-beta-carboline was examined in rat brain synaptosomal membranes treated with irazepine, an alkylating benzodiazepine. Under incubation conditions that resulted in a 25-33% reduction in the Bmax of [3H]diazepam binding, only modest (less than 8.5%) reductions in the Bmax of [3H]3-carboethoxy-beta-carboline were observed. The differential effects of irazepine on the binding of these two compounds may be explained by the presence of multiple areas or "domains" on the benzodiazepine receptor.     

Preparation and application of a photoreactive thrombin analogue: binding to human platelets

alpha-Thrombin has previously been shown to bind to specific, saturable glycoproteins on the platelet surface. Modification of the thrombin active site with tosyllysyl chloromethyl ketone (TosLysCH2Cl) does not alter thrombin's binding characteristics. Interaction of alpha-thrombin with high-affinity binding sites (KD = 10(-9) M) initiates the platelet response which involves proteolytic hydrolysis of this glycoprotein. Although TosLysCH2Cl--thrombin binds to and competes for the same sites as alpha-thrombin, it cannot induce platelet stimulation because it is enzymatically inactive. In this study, we describe the preparation and application of photoreactive tritium-labeled thrombin analogues. The alpha-thrombin derivative retains its platelet-stimulating and enzymatic activities and, upon photoactivation, covalently binds to specific platelet membrane components. When freshly washed human platelets are exposed to less than saturation doses (less than or equal to 2 nM) of the thrombin derivatives in the dark and photoactivated, a single labeled complex is detected. The same experiment with greater than saturating doses (greater than or equal to 20 nM) of the thrombin derivative yields a similar complex as well as two additional ones. Molecular weight estimates of these thrombin-bound complexes were obtained by gel filtration and NaDodSO4--polyacrylamide gel electrophoresis. The low dose (high affinity) complex with TosLysCH2Cl--thrombin has an approximate molecular weight of 200 000, while that with active alpha-thrombin is smaller, approximately 120 000, due to enzymatic cleavage. The additional complexes detected with the high thrombin dose had estimated molecular weights of 400 000 and 46 000, respectively, and appeared to be the same for TosLysCH2Cl--thrombin and for the alpha-thrombin coupled platelets. These isolated complexes appear to correspond to the two previously detected populations of thrombin binding sites on the platelet.     

Micropithecus clarki, a small ape from the Miocene of Uganda.

Micropithecus clarki, from Miocene sediments of Napak, Uganda, is the smallest known hominoid primate, living or fossil. In facial morphology it is very similar to extant gibbons. Dentally, it is most similar to the small apes from the Miocene of Kenya, Dendropithecus and Limnopithecus. All of the apes from the early Miocene of East Africa seem to represent a single phyletic group that could be easily derived from the Oligocene apes known from the Fayum of Egypt. Pliopithecus from the Miocene of Europe is more closely allied with the Oligocene radiation than with the later East African radiation.     

The use of amino acid sequence analysis in assessing evolution

The thirteen year history of assessing evolution by amino acid sequence analysis has made apparent the limitations imposed upon this system by the finite nature of the characters. This finiteness exists on several levels and ultimately expresses itself as parallelism, back mutation and the retention of primitive characters in the sequences of proteins from present day species and the putative ancestral protein chains. Sequence analysis shares these problems with other molecular approaches, but because it is concerned both with the nucleotide substitutions in the genome and with the functional roles of proteins, it has unique advantages. For example, the large fluctuation in the rate of fixation of mutations in a protein's evolution can be detected and used to point out the unreliability of any molecular clock for estimating divergence dates. Moreover, when consideration is given to studies which assign functional significance to specific amino acid sites in a protein, changes in function during the descent of a protein can be appreciated and their significance correlated with organismal evolution.