bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of temperature, friction, and random forces on folding of the B‐domain of staphylococcal protein A: All‐atom molecular dynamics in implicit solvent
Authors: Jagielska Anna , Scheraga Harold A.
Published: February 2007

The influences of temperature, friction, and random forces on the folding of protein A have been analyzed. A series of all‐atom molecular dynamics folding simulations with the Amber ff99 potential and Generalized Born solvation, starting from the fully extended chain, were carried out for temperatures from 300 to 500 K, using (a) the Berendsen thermostat (with no explicit friction or random forces) and (b) Langevin dynamics (with friction and stochastic forces explicitly present in the system). The simulation temperature influences the relative time scale of the major events on the folding pathways of protein A. At lower temperatures, helix 2 folds significantly later than helices 1 and 3. However, with increasing temperature, the folding time of helix 2 approaches the folding times of helices 1 and 3. At lower temperatures, the complete formation of secondary and tertiary structure is significantly separated in time whereas, at higher temperatures, they occur simultaneously. These results suggest that some earlier experimental and theoretical observations of folding events, e.g., the order of helix formation, could depend on the temperature used in those studies. Therefore, the differences in temperature used could be one of the reasons for the discrepancies among published experimental and computational studies of the folding of protein A. Friction and random forces do not change the folding pathway that was observed in the simulations with the Berendsen thermostat, but their explicit presence in the system extends the folding time of protein A. © 2007 Wiley Periodicals, Inc. J Comput Chem 2007
Accuracy of distributed multipoles and polarizabilities: Comparison between the LoProp and MpProp models
Authors: Söderhjelm P. , Krogh J. W. , Karlström G. , Ryde U. , Lindh R.
Published: February 2007

Localized multipole moments up to the fifth moment as well as localized dipole polarizabilities are calculated with the MpProp and the newly developed LoProp methods for a total of 20 molecules, predominantly derived from amino acids. A comparison of electrostatic potentials calculated from the multipole expansion obtained by the two methods withab initioresults shows that both methods reproduce the electrostatic interaction with an elementary charge with a mean absolute error of ∼1.5 kJ/mol at contact distance and less than 0.1 kJ/mol at distances 2 Å further out when terms up to the octupole moments are included. The polarizabilities are tested with homogenous electric fields and are found to have similar accuracy. The MpProp method gives better multipole moments unless diffuse basis sets are used, whereas LoProp gives better polarizabilities. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
A 45‐ns molecular dynamics simulation of hemoglobin in water by vectorizing and parallelizing COSMOS90 on the earth simulator: Dynamics of tertiary and quaternary structures
Authors: Saito Minoru , Okazaki Isao
Published: February 2007

Molecular dynamics (MD) simulations of human adult hemoglobin (HbA) were carried out for 45 ns in water with all degrees of freedom including bond stretching and without any artificial constraints. To perform such large‐scale simulations, one of the authors (M.S.) accelerated his own software COSMOS90 on the Earth Simulator by vectorization and parallelization. The dynamical features of HbA were investigated by evaluating root‐mean‐square deviations from the initial X‐ray structure (an oxy T‐state hemoglobin with PDB code: 1GZX) and root‐mean‐square fluctuations around the average structure from the simulation trajectories. The four subunits (α1, α2, β1, and β2) of HbA maintained structures close to their respective X‐ray structures during the simulations even though no constraints were applied to HbA in the simulations. Dimers α1β1 and α2β2 also maintained structures close to their respective X‐ray structures while they moved relative to each other like two stacks of dumbbells. The distance between the two dimers (α1β1 and α2β2) increased by 2 Å (7.4%) in the initial 15 ns and stably fluctuated at the distance with the standard deviation 0.2 Å. The relative orientation of the two dimers fluctuated between the initial X‐ray angle −100° and about −105° with intervals of a few tens of nanoseconds. © 2007 Wiley Periodicals, Inc. J Comput Chem 2007
“Quasi flexible” automatic docking processing for studying stereoselective recognition mechanisms, part 2: Prediction of ΔΔG of complexation and 1H‐NMR NOE correlation
Authors: Alcaro S. , Gasparrini F. , Incani O. , Caglioti L. , Pierini M. , Villani C.
Published: February 2007

The purpose of this work is to apply the global molecular interaction evaluation (“Glob‐MolInE”) computational protocol to the study of two molecular complexes characterized by a chiral selector and a couple of enantiomeric selectands experimentally known to give large difference in the free energy of complexation much higher than the experimental error normally associated to the molecular mechanic calculations. We have considered the well known diastereomeric complexes between the selector (S)‐N‐(3,5‐dinitrobenzoyl)‐leucine‐n‐propylamide (S)‐1 and the selectands (R) or (S)‐N‐(2‐naphthyl)‐alanine methyl ester 2, widely studied by enantioselective HPLC, NMR and X‐ray. The experimental difference of free energy of complexation between [(S)‐1•(R)‐2] and [(S)‐1•(S)‐2] (−1.34 kcal/mol) was reproduced by the new computational protocol with an excellent confidence error. Detailed results about the conformational search, the “quasi‐flexible” docking and the thermodynamic estimation are presented in this work. A remarkable correlation between the theoretical results and experimental data (NOE measurements, X‐ray crystallographic structure of the [(S)‐1•(S)‐2] complex and the free energy of complexation) supports the validity of the computational approach and underline the importance of the conformational multiplicity in the definition of the macroscopic properties of the complex in solution. © 2007 Wiley Periodicals, Inc. J Comput Chem 2007
Commentaries on the placebo concept in psychotherapy
Authors: Thorn Beverly
Published: February 2007

This editorial note introduces the next five commentaries on the placebo effect in psychotherapy. These commentaries follow the July, 2005 publication of a special series of articles in the Journal of Clinical Psychology, entitled “The Placebo Concept in Psychotherapy.” © 2007 Wiley Periodicals, Inc. J Clin Psychol 63: 371–372, 2007.
Stability of negative self‐structures: A longitudinal comparison of depressed, remitted, and nonpsychiatric controls
Authors: Dozois David J. A.
Published: February 2007

To be considered a vulnerability marker for depression, a variable should, in addition to demonstrating sensitivity and specificity, also show evidence of temporal stability (i.e., remain present in the absence of depressive symptomatology). Although many cognitive factors are associated with depression, the majority of them appear to be episode rather than vulnerability markers. This study examined cognitive organization of positive and negative interpersonal and achievement content in clinically depressed, remitted, and nonpsychiatric controls. At initial assessment, a sample of 54 clinically depressed individuals and 37 never‐depressed controls completed self‐report measures of positive and negative automatic thoughts and two cognitive organizational tasks. They were retested 6 months later when half of the depressed group no longer met diagnostic criteria for major depression. Negative automatic thoughts decreased and positive automatic thoughts increased significantly in individuals who had improved clinically. The organization of negative interpersonal content remained stable despite symptom amelioration, but negative achievement content was less interconnected at follow‐up in those patients who had improved. The structure of relational schemas, in particular, appears to be stable and may be an important cognitive vulnerability factor for depression. © 2007 Wiley Periodicals, Inc. J Clin Psychol 63: 319–338, 2007.
The placebo effect: “Relatively large” and “robust” enough to survive another assault
Authors: Wampold Bruce E. , Imel Zac E. , Minami Takuya
Published: February 2007

The evidence related to the placebo effect is discussed, and it is emphasized that the descriptors “relatively large” and “robust” are appropriate in the context in which they were used. Basic science and clinical trials, when interpreted properly, have revealed that the placebo effect is indeed a real phenomenon. J. Hunsley and R. Westmacott (this issue) as well as A. Hróbjartsson and P. C. Gøtzsche (this issue) are concerned that B. E. Wampold, T. Minami, S. C. Tierney, T. W. Baskin, and K. S. Bhati (2005) overstated the clinical effects of placebo when it was never B. E. Wampold et al.'s (2005) intention to make inferences about clinical utility; however, it is shown that the placebo effect exceeds many accepted medical interventions. © 2007 Wiley Periodicals, Inc. J Clin Psychol 63: 401–403, 2007.
Interpreting the magnitude of the placebo effect: Mountain or molehill?
Authors: Hunsley John , Westmacott Robin
Published: February 2007

The ambiguity involved in interpreting numbers and words is central to Hróbjartsson and Gøtzsche's (this issue) claim of “powerful spin” in the Wampold, Minami, Tierney, Baskin, and Bhati (2005) re‐analysis of their meta‐analytic findings on the placebo effect in medicine. Meta‐analytic results reported by the two sets of authors are nearly identical, yet their conclusions differ dramatically. In our comment, we discuss the findings of the respective authors and consider options for representing and interpreting the magnitude of meta‐analytic effect size estimates. We conclude that although the meta‐analyses described indicate that placebo effects do exist and cannot be dismissed as unimportant, given contextual information, it is consistent with existing research to describe the obtained mean effect size for placebos in medicine as small in magnitude. © 2007 Wiley Periodicals, Inc. J Clin Psychol 63: 391–399, 2007.
Good grief and not‐so‐good grief: Countertransference in bereavement therapy
Authors: Hayes Jeffrey A. , Yeh Yun‐Jy , Eisenberg Alanna
Published: February 2007

This study examined the relationship between therapists' grief related to the death of a loved one and clients' perceptions of the process of bereavement therapy. Mail survey data were obtained from 69 client–therapist dyads. Results indicated that the extent to which therapists missed deceased loved ones was inversely related to client perceptions of therapist empathy, but not to client ratings of the alliance, session depth, or therapist credibility. Therapist acceptance of the death of a loved one was unrelated to any of the dependent measures. Results are discussed in terms of countertransference and its management. © 2007 Wiley Periodicals, Inc. J Clin Psychol 63: 345–355, 2007.
The story of placebo effects in medicine: Evidence in context
Authors: Wampold Bruce E. , Imel Zac E. , Minami Takuya
Published: February 2007

In 2005, in an article reviewing the evidence related to the placebo effect that was derived from clinical trials in medicine and psychotherapy, B. E. Wampold, T. Minami, S. C. Tierney, T. W. Baskin, and K. S. Bhati re‐analyzed studies contained in A. Hróbjartsson and P. C. Gøtzsche's (2001) meta‐analysis of trials that contained placebo and no‐treatment conditions. Whereas Hróbjartsson and Gøtzsche (2001) concluded that the placebo effect was weak at best, Wampold et al. (2005) concluded that it was “robust.” Hróbjartsson and Gøtzsche (this issue) challenged Wampold et al.'s (2005) conclusion, claiming essentially that the results of clinical trials containing placebo and no‐treatment conditions are not sufficient to claim that the placebo effect exists to any substantial degree. In this article, it is shown that when properly interpreted by considering theory, method, context, and related research, the results of clinical trials support the existence of a placebo effect. In short, the placebo effect appears in those instances where it is expected. © 2007 Wiley Periodicals, Inc. J Clin Psychol 63: 379–390, 2007.
Imaging and analysis of 3‐D structure using a dual beam FIB
Authors: McGrouther D. , Munroe P.R.
Published: February 2007

The application of focused ion beam instrumentation in the generation of three‐dimensional microstructural data is described. The methodologies used to acquire and manipulate this data are explained, and the technique is illustrated by a number of examples from the material sciences. The limitations of this method, and practical pointers to the generation of meaningful data, are also discussed. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Subcellular imaging of isotopically labeled carbon compounds in a biological sample by ion microprobe (NanoSIMS)
Authors: Clode Peta L. , Stern Richard A. , Marshall Alan T.
Published: February 2007

Here we demonstrate the technique of nanoscale secondary ion mass spectrometry, utilizing the Cameca NanoSIMS50® ion microprobe, to detect and image the metabolism of an isotopically labeled compound (NaH13CO3) in a biological sample. In particular, we have designed and verified protocols for imaging the subcellular distribution and determining the relative abundance of labeled 13C, within the coral Galaxea fascicularis. Analyses were conducted on 1‐μm thick sections of resin‐embedded material, using both scanned (mapping) and static (spot analysis) Cs+ primary ion beam of ∼100 nm diameter. Using these samples we establish that NanoSIMS has adequate mass resolution to reliably distinguish 13C from potential isobaric interference by 12C1H and that data extracted from ion maps are comparable to those acquired by spot analyses. Independent of the method of acquisition, ratioing of 13C to the naturally abundant 12C is essential if meaningful data, which can be statistically compared to standard and control samples, are to be obtained. These results highlight the potential of NanoSIMS for intracellular tracking of a variety of organic and inorganic compounds labeled with stable isotopes of C, N, O, S, P, and halogens. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
New bounds on the edge number of ak‐map graph
Authors: Chen Zhi‐Zhong
Published: February 2007

It is known that for every integerk ≥ 4, eachk‐map graph withnvertices has at mostkn− 2kedges. Previously, it was open whether this bound is tight or not. We show that this bound is tight fork = 4, 5. We also show that this bound is not tight for large enoughk(namely,k ≥ 374); more precisely, we show that for every$0 < \epsilon < {3 \over 328}$and for every integer$k \ge {140 \over {41\epsilon}}$, eachk‐map graph withnvertices has at most$({325 \over 328} + \epsilon){kn} - 2{k}$edges. This result implies the first polynomial (indeed linear) time algorithm for coloring a givenk‐map graph with less than 2kcolors for large enoughk. We further show that for every positive multiplekof 6, there are infinitely many integersnsuch that somek‐map graph withnvertices has at least$({11 \over 12}{k} + {1 \over 3}) {n}$edges. © 2007 Wiley Periodicals, Inc. J Graph Theory 55: 267–290, 2007
Anatomical and metabolic assessment of prostate using a 3‐Tesla MR scanner with a custom‐made external transceive coil: Healthy volunteer study
Authors: Kaji Yasushi , Kuroda Kagayaki , Maeda Takaki , Kitamura Yuri , Fujiwara Toshitaka , Matsuoka Yuichiro , Tamura Mitsuru , Takei Naoyuki , Matsuda Tsuyoshi , Sugimura Kazuro
Published: February 2007

Purpose

To examine the possibility of using a 3 Tesla (T) magnetic resonance (MR) scanner with a custom‐made external coil to obtain ductal details of the prostate, high‐quality spectra, and metabolite mapping corresponding to prostate zonal anatomy in healthy volunteers.

Materials and Methods

MRI and two‐dimensional (2D) chemical shift imaging (CSI) were performed in 16 healthy volunteers using a 3T scanner with a custom‐made external transmit‐receive (transceive) coil. Visualization of the prostatic duct‐like structure was analyzed on T2‐weighted (T2W) images. The resolution of the metabolite peaks and the distribution of metabolites in CSI were also assessed.

Results

In the axial plane, 3‐mm‐thick images were better than 4‐mm‐thick images with the same voxel volume for assessing duct‐like structures and prostatic urethra. Differentiation between inner and outer citrate (Cit) peaks was frequently observed (29 out of 30). The mean peak area ratio of choline (Cho) plus creatine (Cr) over Cit in the peripheral zone (PZ) was significantly lower than in the transition zone (TZ) (P = 0.014).

Conclusion

3T MR examinations of the prostate using an external coil allow information to be collected about the details of duct‐like structures, the high‐quality spectra of Cit, and the zone‐specific distribution of metabolites. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Effects of RF inhomogeneity at 3.0T on ramped RF excitation: Application to 3D time‐of‐flight MR angiography of the intracranial arteries
Authors: Eissa Amir M. , Wilman Alan H.
Published: February 2007

Purpose

To demonstrate the effects of inherent RF inhomogeneity on ramped RF excitation at 3.0T, and to introduce a simple correction for improving visualization of distal intracranial arteries in three‐dimensional time‐of‐flight MR angiography (3D‐TOF‐MRA).

Materials and Methods

At 3.0T, the effects of RF inhomogeneity arising from RF interference were demonstrated for ramped RF excitation in intracranial 3D‐TOF‐MRA. Computer simulations and experiments on phantoms and eight normal volunteers were performed. Four different ramp shapes were tested as a possible means of countering the reduced RF field that affects the distal intracranial arteries.

Results

RF destructive interference alters the ramp pulse shape, which is problematic for vessels that proceed from the center to the edge of the brain. Increasing the ramp pulse slope was shown to be an effective yet simple correction to counter the falling‐off of the RF field toward the periphery of the head. With this approach, circle‐of‐Willis 3D‐TOF‐MRA studies had improved distal visibility.

Conclusion

Ramped RF excitation is severely affected by RF interference at 3.0T, which makes the ramp profile suboptimal for distal intracranial blood vessels. A simple correction of the ramp slope can make a marked improvement. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Malignant‐lesion segmentation using 4D co‐occurrence texture analysis applied to dynamic contrast‐enhanced magnetic resonance breast image data
Authors: Woods Brent J. , Clymer Bradley D. , Kurc Tahsin , Heverhagen Johannes T. , Stevens Robert , Orsdemir Adem , Bulan Orhan , Knopp Michael V.
Published: February 2007

Purpose

To investigate the use of four‐dimensional (4D) co‐occurrence‐based texture analysis to distinguish between nonmalignant and malignant tissues in dynamic contrast‐enhanced (DCE) MR images.

Materials and Methods

4D texture analysis was performed on DCE‐MRI data sets of breast lesions. A model‐free neural network‐based classification system assigned each voxel a “nonmalignant” or “malignant” label based on the textural features. The classification results were compared via receiver operating characteristic (ROC) curve analysis with the manual lesion segmentation produced by two radiologists (observers 1 and 2).

Results

The mean sensitivity and specificity of the classifier agreed with the mean observer 2 performance when compared with segmentations by observer 1 for a 95% confidence interval, using a two‐sided t‐test with α = 0.05. The results show that an area under the ROC curve (Az) of 0.99948, 0.99867, and 0.99957 can be achieved by comparing the classifier vs. observer 1, classifier vs. union of both observers, and classifier vs. intersection of both observers, respectively.

Conclusion

This study shows that a neural network classifier based on 4D texture analysis inputs can achieve a performance comparable to that achieved by human observers, and that further research in this area is warranted. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Connexin 43 gap junction proteins are up‐regulated in remyelinating spinal cord
Authors: Roscoe W.A. , Messersmith E. , Meyer‐Franke A. , Wipke B. , Karlik S.J.
Published: February 2007

Alterations in the expression of gap junction proteins have previously been observed in several diseases affecting the central nervous system; however, the status of connexin 43 (Cx43) has not yet been reported in spinal cord remyelination. We studied Cx43 expression in demyelination and remyelination by using a chronic guinea pig model of experimental allergic encephalomyelitis (EAE). Hartley guinea pigs were immunized with homogenized whole CNS and complete Freund's adjuvant. Animals became chronically ill by day 40 postimmunization, and animals with paralysis were entered into the study. Animals were treated on days 40–60 postimmunization with either saline or drugs that promote remyelination: an adenosine amine congener (100 μg/kg), an anti‐α4‐integrin blocker (CT301; ELN 69299; 30 mg/kg), or a combination of both drugs. Remyelination was induced in all drug‐treated groups. Cx43 expression was virtually absent in demyelinated lesions of saline‐treated controls compared with healthy tissue and normal appearing white matter (P < 0.001), whereas Cx43 was considerably increased (300–500%) in remyelinating lesions of all treatment groups (P < 0.001), most notably in CT301‐treated animals. These changes in Cx43 expression indicate that Cx43 may beimportant for recovery from neuroinflammation. © 2007 Wiley‐Liss, Inc.
Yield coefficients in dependence on milieu conditions and cell states IV. Ethanol production by yeasts. Yield coefficients. IV
Authors: Heinritz B. , Ghildyal N. P. , Ringpfeil M.
Published: February 2007

The effect of yeast‐cell state on the rate and yield of ethanol synthesis in semicontinuous and continuous fermentation of carbohydrates was investigated in order to increase the ethanol production rates and to obtain ethanol yields close to theoretically calculated values.

Differences between the initiation of ethanol synthesis in cells of the single‐cell state and of the budding‐cell state were obtained. It could be shown that it is advantageous to switch to anaerobic conditions for ethanol production when yeast cells enter the budding‐cell state during aerobic cultivation.

Thus, by considering cell‐state distribution of yeast population the specific ethanol production rate and the total ethanol yield could be improved in continuous sucrose fermentation by Saccharomyces cerevisiae H 155. The cell‐state distribution was changed by replacement of aged cells in the single‐cell state by aerobically precultivated budding cells which caused an increased process stability.

These results show that investigations of the dependence of yield and rate of ethanol production on cell states are a powerful means to intensify the ethanol production.
Metabolism of sulfur‐containing amino acids in the dermatophyte Microsporum gypseum I. Neutral amino acids
Authors: Kunert J.
Published: February 2007

The dermatophyte Microsporum gypseum was cultivated on a glucose‐arginine medium to which on out of six sulfur‐containing amino acids was added (l‐cystine, l‐djenkolic acid, dl‐lanthionine dl‐homocystine, l‐methionine, or l‐methionine‐sulfone at a concentration of 5 mm with respect to sulfur content). The addition of these substances did not stimulate the growth and some amino acids (djenkolic acid and particularly methionine and methionine‐sulfone) were inhibitory. All tested compounds were utilized during the growth not only as sulfur source but as a source of carbon and nitrogen as well. In four substrates excess sulfur was excreted after oxidation into the medium in the form of sulfate. Small amounts of sulfite were also observed. It usually reacted with remaining disulfides in the medium forming S‐sulfo compounds (R‐S.SO3H). Cystine and djenkolic acid were oxidized rapidly and completely. In contrast, lanthionine and particularly homocystine were oxidized slowly and only after a longer adaptation. To some extent lanthionine was already oxidized extracellularly in the medium. With methionine and its sulfone, excess sulfur was not removed by oxidation but by demethiolation to methane thiol and further volatile products.
Geförderte Plaquebildung in RNA‐Phagen/Bakterien‐Systemen unter dem Einfluß oberflächenaktiver Präparate
Authors: Menzel G.
Published: February 2007

The effect of 21 surfactants on the plaque formation was tested in three RNA‐phages/Escherichia coli systems and in one RNA‐phage/Psedomonas aeruginosa system. Especially anionic detergents proved to be able to influence the plaque formation substantially. In high concentrations of Metaupon, Fekunil 602, Fekunil S‐BA, Emulgator W 270, and Emulgator O‐BA the plaque formation by the phages M 12 and f 2 was inhibited and in low concentrations it was promoted. In the system Qβ/E. coli AB 301 the effect of the detergents mentioned was restricted to the prevention of the appearance of plaques. The detergent E 30 brought about only plaque inhibitions, too, in all used RNA‐phages/E. coli systems. The treatment with effective detergents in the system PP7/P. aeruginosa, however, increased only the number of plaques.

This phenomenon was evident in the formation of radiate plaque patterns in the lawn of bacteria. In the case of RNA‐phages of E. coli the formation of such trains of lysis depends on the choice of the nutritive medium. The addition of the detergent Fekunil 602 at different times after the contact between phages and host bacteria affects the length of the beams of lysis. The ionogenity of surfactants seems to be of importance for the formation of radiate plaque patterns, since the tested cationic compound and the nonionic surfactants, contrary to anionic surfactants, did not cause any beams of lysis.
An electrochemical method for determination of cell respiration
Authors: Riedel K. , Liebs P. , Renneberg R.
Published: February 2007

The respiration of microorganisms was determined with a sensor composed of microorganisms and an oxygen electrode. The microorganisms (suspensions of about 100 μl) are sedimented by centrifugation in a special tube on a very thin paper layer (diameter 4 mm). This paper layer is sandwiched between a polyethylene membrane and a dialysis membrane. A linear relationship is obtained between the current and the cell mass of Bacillus subtilis (between 0.05–0.35 mg dry weight per electrode preparation). When an assimilable substrate is added to the measuring solution the respiration rate is increased. It is possible to determine very fast changes in the respiration rates (1–5 sec). The application of this electrode system for investigations of the physiological state of cells during the growth cyclus is demonstrated.
Proteine der Zellwand von Escherichia coli: Eine dem thermolabilen Enterotoxin (LT) ähnliche Substanz
Authors: Seltmann G. , Beer W. , Voigt W. , Wolter E.‐J. , Grahlow W.‐D.
Published: February 2007

In ultrasonic extracts of all 19 investigated non‐enterotoxigenic E. coli strains a substance (LTLS) could be detected reacting positively in all tests which are commonly used to detect specifically E. coli thermolabile enterotoxin (LT). Culture supernatants of these strains in general did not contain LTLS in detectable amounts. LTLS can be found in the whole cell, however, the membrane fraction contains the highest quantities. Released LTLS appears mainly aggregated with components of the cell wall, especially with lipopolysaccharides. This fact in combination with the very low quantities produced by the bacteria renders very difficult purification of LTLS.
Denitrifikation mit Cellulose als einzigem Wasserstoffdonator
Authors: Sommer K. , Ottow J. C. G.
Published: February 2007

With cellulose as a single energy source (hydrogen donator) and nitrate as an electron acceptor, 18 strains of denitrifying bacteria were isolated by enrichment technique and identified as members of Cellulomonas sp. (6 strains), Pseudomonas fluorescens (6) and Acinetobacter‐Moraxella sp. (3). Three gram‐negative rods could not be classified so far. In model experiments (Fig. 1) with a synthetic cellulose‐KNO3‐broth (pH 7.3) denitrification (N2, N2O) was followed (Fig. 2 and 3) using Cellulomonas sp. strain 20 and Pseudomonas fluorescens nr. 15, respectively, as test organisms. Under complete anaerobic conditions, no denitrification occurred. However, in the presence of oxygen (12.5 vol.‐% O2) both respiration and denitrification (N2 and N2O) could be ascertained by gaschromatography. Rapid increase in CO2 confirmed active cellulolytic activity (Fig. 2 and 3).
Untersuchungen zur Regulation der Ammoniumassimilation von Candida maltosa
Authors: Casper P. , Bode R. , Birnbaum D.
Published: February 2007

Activities of ammonia‐metabolizing enzymes from Candida maltosa were measured. The synthesis of glutamate and glutamine involves three primary enzymes: glutamate dehydrogenase (GDH), glutamine synthetase (GS), and glutamate synthase (GOGAT). This yeast has two distinct GDH, the first responsible for glutamate catabolism, and the second solely biosynthetic. The GS is derepressed during growth on low ammonia or on a variety of alternative nitrogen sources, whereas the catabolic GDH (NAD) is repressed under this conditions. Ammonia limitation did not significantly affect GOGAT as well as biosynthetic GDH (NADP) levels. The relatively low Km‐value for ammonia suggest that the GS is catalytically active during cell growth on low concentrations of ammonia. It seems that under N‐limitation ammonia assimilation is achieved via GS/GOGAT and under N‐excess via GDH/GS.
Metabolism of sulfur‐containing amino acids in the dermatophyte Microsporum gypseum II. Acidic amino acid derivatives
Authors: Kunert J.
Published: February 2007

The dermatophyte Microsporum gypseum was cultivated on a glucose‐arginine medium supplemented with five strongly acidic derivatives of cysteine (l‐cysteine sulfinic acid, l‐cysteic acid, l‐serine‐0‐sulfate and taurine at a concentration of 5 mmol/l, and l‐S‐sulfocysteine at a concentration of 2.5 mmol/l). The addition of these substances did not stimulate the growth as compared with the control containing 0.5 mmol/l cystine. Cysteine sulfinic acid and cysteic acid showed rather inhibitory effects. A strong inhibition of the growth was caused by the presence of serine sulfate. During the growth, all substances investigated were gradually consumed and utilized not only as a source of sulfur but of nitrogen and carbon as well. Cysteine sulfinic acid and S‐sulfo‐cysteine were utilized most rapidly. Cysteic acid was also rapidly utilized but after a certain adaptation. Taurine was utilized slowly and serine sulfate very slowly. Excess sulfur contained in the substances used was excreted into the medium in the form of sulfate. Sulfate excretion was most rapid with cysteine sulfinic acid and slowest with taurine. With cysteine sulfinic acid, S‐sulfocysteine and cysteic acid, small amounts of sulfite were found in the medium. The results obtained are in accordance with the presumption that cysteine sulfinic acid (but not cysteic acid and taurine) is an intermediate of cysteine catabolism in dermatophytes.
Transformation of the industrially important yeasts Candida maltosa and Pichia guilliermondii
Authors: Kunze G. , Petzoldt C. , Bode R. , Samsonova I. A. , Böttcher F. , Birnbaum D.
Published: February 2007

Saccharomyces cerevisiae, Candida maltosa and Pichia guilliermondii have been transformed at different frequencies by the plasmid p Ye(ARG4)411 which carried the Sacch. cerevisiae ARG4 gene inserted into pBR322. Our results strongly suggest that the transformants possessed extrachromosomally maintained and autonomously replicating plasmid DNA from which ARG4 gene and β‐lactamase gene were expressed.
Electron microscopic study of purified polysaccharide components glucans and mannan of the cell walls in the yeast Saccharomyces cerevisiae
Authors: Kopecká Marie
Published: February 2007

In this study electron‐microscopic characteristics of platinum shadowed or negatively stained preparations of purified β‐(1 → 3)‐d‐glucan, β‐(1 → 6)‐d‐glucan, and mannan were examined. These polysaccharides were isolated from cell walls of the yeast Saccharomyces cerevisiae. While purified samples of β‐(1 → 6)‐d‐glucan and mannan proved to be amorphous in structure and homogenous in appearance, the purified β‐(1 → 3)‐d‐glucan, isolated and presented to us as alkali‐insoluble yeast glucan A2, was not homogenous. It consisted of (i) fibrillar component, (ii) amorphous matrix, and (iii) chitin bud scars. The ultrastructure of β‐(1 → 3)‐d‐glucan present in the glucan A2 sample did not change after treatment with 0.5 m acetic acid at 75°C for 2 hours. After treatment with 1 m NaOH for 3 days at 4 °C scar material was removed by centrifugation and after a subsequent acidification of supernatant with acetic acid both the microfibrillar and the amorphous components were still present. It was concluded that β‐(1 → 3)‐d‐glucan component consists of molecules probably differing in their physico‐chemical properties such as D. P., the degree of branching, conformation, and that cannot be separated by the methods currently used for their isolation.
Charakterisierung und Differenzierung fluoreszierender Pseudomonaden mit Hilfe von Substratverwertungsstudien
Authors: Schöpp W. , Toaspern Cornelia , Tauchert H.
Published: February 2007

A rapid procedure is described for detecting and differentiating pseudomonads by their ability to degrade substrates with diverse physico‐chemical properties, including volatile and non‐volatile water‐insoluble compounds, strong organic acids and bases, surfactants, disinfectants, and other toxic substances. The bacteria are embedded in an agar medium containing mineral salts and exposed to about 5 mg amounts of six to eight different substrates placed on the surface of an agar plate. After incubation at 25°C for 24 hrs, growth zones around utilizable substrates may be used to differentiate various Pseudomonas strains and species.
Säureausscheidung und Kaliumaufnahme der Hefe Hansenula henricii Hg 48‐2 in Chemostat‐Kulturen bei verschiedenen pH‐Werten
Authors: Uebel B. , Huth J.
Published: February 2007

Proton release and K+‐content of biomass in chemostat cultures of the yeast Hansenula henricii Hg 48‐2 were measured in 12 steady states at different K+‐concentrations in the medium reservoire (sR) and at different pH‐values in the culture. Competitive inhibition of K+‐uptake by H+‐ions, described for non‐growing yeast cultures, could not be found. The growing cultures show H+/K+ exchange quotients between 8:1 and 40:1. The actual value of the H+/K+ exchange quotient is determined by the relation between the NH+4‐and the K+‐content in the medium reservoire. The exchange quotient is not influenced by the concentration of biomass and slightly modulated by the pH‐value in the culture. The difference between the H+ excretion and the K+ uptake is caused mainly by the growth‐dependent NH+4 demand. The K+ content of the biomass increases non‐linear with increasing K+ concentrations sR constant pH values. There exists a linear relationship between the yield coefficient YH+ and the biomass concentration in the steady state χ. These findings are discussed as a result of interactions between potassium‐, nitrogen‐and oxygen‐limitation.
Synergistic effect of cobalt on the induction by A‐factor of the formation of aerial mycelium and anthracyclines by a blocked mutant of Streptomyces griseus
Authors: Gräfe U. , Eritt I. , Riesenberg D.
Published: February 2007

Cobalt ions synergistically supported the inducing effect of A‐factor 1a on the formation of aerial mycelium and anthracyclines by the blocked S. griseus mutant 86. This suggested an involvement of effector 1a in the transport or metabolism of this trace element. In accordance with the proposed role of 1a as an autoregulatory secondary metabolite, the parent strain S. griseus JA 3933 secreted 1a into the medium after a decrease of the specific growth rate and before the onset of antibiotic production.
An esterase as marker enzyme on the outer membrane of Acinetobacter calcoaceticus
Authors: Claus R. , Fischer B. , Kleber H.‐P.
Published: February 2007

An esterase activity which hydrolyses palmitoyl‐CoA was found in the membrane fraction of Acinetobacter calcoaceticus 69/V. Other tested strains of Acinetobacter also possessed this enzyme activity. The esterase is constitutive, fully active on the surface of intact cells and located on the outer membrane of the bacteria. Besides palmitoyl‐CoA some oxy‐esters and p‐nitrophenyl palmitate were also hydrolyzed. In contrast triglycerides, short‐chain acyl‐CoA esters (C2—C10) and p‐nitrophenyl acetate were not hydrolyzed. The enzyme activity was not influenced by inhibitors of mammalian esterases.
Influence of inorganic phosphate on the lipid synthesis of a phosphate‐deregulated mutant of Streptomyces noursei
Authors: Hänel F. , Gräfe U. , Roth M. , Bormann E. J. , Krebs D.
Published: February 2007

Phosphate‐dependent changes of the mycelial lipid composition were studied in the streptothricin‐producing parental strain Streptomyces noursei JA 3890 b/2 and its mutant RG 2. In contrast to its ancestor, the mutant was capable of producing the antibiotic nourseothricin even when large quantities of inorganic phosphate were present in the medium. The apparent insensitivity of the secondary metabolism to phosphate inhibition corresponds to a decreased level of phospholipids in the presence of excessive inorganic phosphate and, during phosphate limitation, to a much higher production of the alkaline phosphatases. A model is discussed which proposed the control by a common genetic element of both the phospholipid and antibiotic production.
Interactions between three blue‐green algae and herbicide 2,4‐D in culture media
Authors: Kobbia I. A. , El‐Sharouny H. M.
Published: February 2007

Nostoc muscorum, Tolypothrix lanata and Aulosira laxa showed different responses to 2,4‐D herbicide at all concentrations. Low concentrations of the herbicide stimulated chlorophyll a synthesis and promoted growth in all species. The maximum values of chlorophyll a contents were recorded at 50 ppm for Nostoc muscorum and Tolypothrix lanata, and at 10 ppm for Aulosira laxa. Above these levels, chlorophyll accumulation was steadily inhibited in all organisms.

The nitrogenase activities in the three species were markedly inhibited and the degree of inhibition increased with increasing concentrations. Nitrogenase activities were always higher at anaerobic than at aerobic conditions, a phenomenon that was reversed at higher concentrations of 2,4‐D in Nostoc muscorum.
Expression in Escherichia coli of streptococcal plasmid‐determined erythromycin resistance directed by the cat gene promoter of pACYC 184
Authors: Malke H. , Ferretti J. J.
Published: February 2007

The streptococcal erythromycin resistance (Emr) plasmid pSM7 (6.4 kb) and the E. coli vector pACYC184 (4.0 kb) were fused at their single EcoRI sites to form the bifunctional chimeric plasmid pSM7184 (10.4 kb) in which the Emr determinant was placed under control of the chloramphenicol acetyl transferase (cat) promoter of pACYC184. In the sense orientation (orientation I) of pSM7, the cat promoter directed expression of Emr in the E. coli host strains 294 and DB11 more efficiently than did the indigenous transcription signals of pSM7, which were functional in the opposite orientation II. In Streptococcus sanguis (Challis), the level of Emr was independent of the orientation of pSM7 in pACYC184, showing that the cat promoter was not recognized in the grampositive host. The growth of E. coli (pSM7184I) in a defined medium containing glycerol as carbon source, or containing glucose plus extraneous cyclic 3′–5′ adenosine monophosphate (cAMP) led to an Emr level which was 15–30 times higher than that of cultures grown on glucose. These results showed that under control of the cat promoter, Emr is subject to cAMP‐mediated catabolite repression and provided conclusive evidence that the enhancement of Emr expression in E. coli carrying pSM7184I is controlled at the transcriptional level.

Besides enabling us to determine the orientation of transcription of the Emr gene in pSM7 and related vectors, this work also made available new bifunctional cloning vehicles able to replicate in both E. coli and S. sanguis.
Enzym‐Inhibitoren aus Actinomyceten II. Inhibitoren saurer Proteinasen
Authors: Passarge Margrit , Fleck W. F.
Published: February 2007

In the course of a screening program directed toward the isolation and evaluation of inhibitors of carboxyl (acid) proteinases, we have found 0.39% of the investigated strains of microorganisms as producers of pepsin inhibitors. In more than 1543 strains which were isolated from various geographical areas and deposited with the IMET Culture Collection, Jena‐GDR, and which belong to different genera of actinomycetes such as Streptomyces, Actinomadura, Actinoplanes, Micromonospora and non‐identified strains, we have found 6 Streptomyces strains only. Surprisingly, the screening efficiency of the used casein agar spot test and the fibrin‐blue‐technique was very low. As compared with the inhibitor activity of pepstatin the yield of the fermentation broth of 3 wild type strains ranged from 6 to 27 μg/ml. A significant influence of the composition of culture fluids on the inhibitor yield was observed. Supplements by crude glutamine or mixtures of amino acids in culture fluids increased the yield from 3 to 15 times as compared with that of fermentation broth without supplements. After NMG‐mutagenic treatment and use of familiar selection procedures 3.1% inhibitor‐blocked mutants were detected among 480 strains selected.
Modification of ultraviolet sensitivity of the green alga Scenedesmus obliquus (Turpin) Kuetzing by acriflavine
Authors: Rai U. N. , Agrawal S. B.
Published: February 2007

The effect of pre‐ and post‐irradiation treatments with acriflavine on the kinetics of ultraviolet inactivation of the green alga Scenedesmus obliquus (Turpin) Kuetzing has been studied. Acriflavine is found to modify the UV‐doses. Pre‐irradiation treatment of the alga lessens but post‐irradiation treatment adds to the extent of UV‐inactivation. Incorporation of the dye in the algal suspension during irradiation also elicits a protective effect against UV‐inactivation. The observations are suggestive of an instantaneous uptake and incorporation of the dye in UV‐sensitive components of algal cells‐resulting in altered response of the pre‐, during‐, and post‐irradiation dye‐treated alga to UV and provide evidence for the operativity of two repair system, i.e. light‐independent and light‐dependent repair of the lesions in this alga.
The effect of the sugar‐chain on the bioconversion of tomatines by Nocardia restricta
Authors: Belič I. , Karlovšek M. , Kralj B.
Published: February 2007

Tomatines are bioconverted by Nocardia restricta to less polar products by conjugation with l (+)‐lactic acid. The yields of these bioconversions decrease from 50% with α‐tomatine to 5% with δ‐tomatine, depending on the length of the sugar‐chain.
Biotransformation of pinenes XVII. Transformation of α‐and β‐pinenes by means of Armillariella mellea (honey fungus), a parasite of woodlands
Authors: Draczyńska B. , Cagara Cz. , Siewiński A. , Rymkiewicz A. , Zabźa A. , Leufvèn A.
Published: February 2007

A culture of Armillariella mellea species was adapted to carry out microbial transformations of (+), (‐), and (±)‐α‐pinene magnified image and (‐)‐β‐pinene magnified image. The composition of products obtained indicated that allylic hydroxylation of all substrates was the most characteristic reaction for Armillariella mellea species. The hydroxylation occurred either directly in unchanged pinane skeleton yielding among other compounds verbenol (magnified image) and verbenone (magnified image) or was preceded by a cleavage of four‐membered rings in substrates to form a menthane skeleton. The latter reaction leads to allylic alcohols and diols, mainly trans‐sobrerol (magnified image) and 7‐hydroxy‐α‐terpineol (magnified image).
Freeze‐fracture observations of Corynebacterium glutamicum: the occurrence of an outer membrane‐like structure and the influence of temperature on the cytoplasmic membrane
Authors: Richter W. , Hänel F. , Hilliger M.
Published: February 2007

In order to elucidate temperature‐dependent morphological changes in the cell envelope of the Gram‐positive L‐lysine‐overproducing Corynebacterium glutamicum 9366 we carried out freeze‐fracture investigations of native cells and studied their fatty acid composition. In addition to the cytoplasmic membrane C. glutamicum possesses at the periphery of the cell an additional fracture plane which is unusual in Gram‐positive bacteria and is designated here as outer membrane‐like structure. The fracture faces of this layer display a distinguishable appearance in several regions of the cell. Bacteria grown at various temperatures showed changes in the relation of the saturated to unsaturated fatty acids. We demonstrated that the cytoplasmic membrane was affected by these changes in the fatty acid composition.
Nachweis von Eisen‐Transport‐Aktivität in Pasteurella multocida‐Kulturen
Authors: Flossmann K.‐D. , Grajetzki Ch. , Rosner H.
Published: February 2007

It has been established that Pasteurella multocida cultures possess pronounced iron transport activities to accumulate the iron necessary for growth.

Experiments with Fe‐59 confirmed that the bacterial cells are able to acquire iron without direct contact from high molecular iron substrates, such as iron dextrane, ferritine or transferrine. Microbial siderophores of the hydroxamate and phenolate types, such as desferrioxamin B and enterobactine as well as other iron chelators (phenanthroline, citrate and nitrilotriacetate) decrease the bacterial cell growth or iron incorporation and are not relevant for iron transport in P. multocida. The direct analytical identification of siderophores using the reactions by Csaky (hydroxamate type) and Arnow (phenolate type) has proved unsuccessful.

The importance of the mannan cell wall polysaccharide is discussed with respect to the iron transport. Thus in terms of iron accumulation, P. multocida is similar to Yersinia, which also possess an efficient transport system for iron not involving siderophores.
Morphogenetic behaviour of two Streptomyces strains analyzed by the use of chemostats
Authors: Kretschmer S.
Published: February 2007

Streptomyces granaticolor ETH 7347 and Streptomyces hygroscopicus IMET JA 6599 were cultivated in Casamino acids‐limited chemostats. Amino acids served as sole source of energy, carbon and nitrogen, but their limitation affected primarily the catabolism of the mycelia. At different specific growth rates (μ) samples were withdrawn. After staining the cell walls of the mycelia the average length of the cells (mycelial length per cross wall: L/C) and of the hyphal growth units (mycelia‐length per branch: L/N) were determined.

L/C was only slightly influenced by μ. In S. granaticolor the cells were on average 11.5 μm and in S. hygroscopicus about 18.5 μm long.

However, L/N was dependent on μ. Upon a shift from μ = 0.6 to μ = 0.1 L/N was reduced 1.2 fold in S. granaticolor and 1.8 fold in S. hygroscopicus. Especially growth rates below 0.2 stimulated branching. The opposite response of L/N to changes of μ was, however, observed in glucose‐limited chemostat cultures (Riesenberg and Bergter 1979). Thus, the average length of the growth units is not determined by μ per se — even if in both cases the energy source was limited — but by specificities of the nutirent‐dependent metabolism.

Comparison of L/C and L/N showed that in all samples of S. granaticolor cells were smaller than the hyphal growth units, while they were larger in S. hygroscopicus. From a cellular point of view, thus there exist different mechanisms of branching — the single and the multiple branching — which were discussed.