Phylogenetic analysis of a bacterial aerobic degrader of azo dyes.

Eubacterial consensus oligonucleotide primers were used to amplify by polymerase chain reaction the nearly full-length 16S rRNA gene of isolate C7, a gram-negative rod capable of aerobic degradation of azo dyes. The DNA product was cloned and sequenced. Phylogenetic analysis based upon this DNA sequence places C7 within the alpha subdivision of proteobacteria, most closely related to Caulobacter subvibrioides. The phospholipid fatty acid pattern resembles that of caulobacters, with monounsaturated 16- and 18-carbon fatty acids predominating. C7 is unusual in having a monounsaturated branched fatty acid in the phospholipids and exclusively 2-hydroxy fatty acids in the lipid-extracted residue. This organism is of potential use in bioreactors operated for azo dye degradation.     

Patterns of cellular proliferation and migration in the developing tectum mesencephali of the frog Rana temporaria and the salamander Pleurodeles waltl

The development of the tectum mesencephali was studied in the frog Rana temporaria and the salamander Pleurodeles waltl by means of nuclear staining and by labeling of cells with bromodeoxyuridine (BrdU). The general spatial and temporal pattern of cell proliferation and cell migration is the same in both species, despite drastic differences in overall tectal morphology. However, the salamander species differs from the frog species by (1) a generally lower cell proliferation rate, (2) a reduction in the activity of the lateral proliferation zone, and (3) a reduction in the formation of superficial cellular layers. Because point (3) affects processes that occur late in ontogeny, our experiments provide evidence that the simple morphology of the tectum of Pleurodeles waltl, compared with the multilayered tectum of Rana, is a consequence of a paedomorphic alteration of the ancestral developmental pattern of the amphibian tectum.     

Clinical pharmacology of the new COMT inhibitor CGP 28 014

CGP 28 014 is a specific inhibitor of catechol-O-methyltransferase (COMT) in vivo. In humans, the inhibition was assessed by measuring urinary excretion of isoquinolines and with the levodopa test. Following administration of CGP 28 014, urinary excretion of isoquinolines was significantly increased. In rats, CGP 28 014 reduced plasma and striatal concentrations of 3-O-methyldopa (30MD) in a dose-dependent manner. Acute and subchronic administration of CGP 28 014 alone or in combination with the peripherally acting decarboxylase inhibitor benserazide decreased plasma 30MD as an index of COMT inhibition by about 50%. There seems to be a close relationship between the time-course of plasma concentrations of CGP 28 014 and the extent of COMT inhibition assessed by the 30MD/DOPA ratio in plasma.     

PocketOptimizer 2.0: A modular framework for computer-aided ligand-binding design

The ability to design customized proteins to perform specific tasks is of great interest. We are particularly interested in the design of sensitive and specific small molecule ligand-binding proteins for biotechnological or biomedical applications. Computational methods can narrow down the immense combinatorial space to find the best solution and thus provide starting points for experimental procedures. However, success rates strongly depend on accurate modeling and energetic evaluation. Not only intra- but also intermolecular interactions have to be considered. To address this problem, we developed PocketOptimizer, a modular computational protein design pipeline, that predicts mutations in the binding pockets of proteins to increase affinity for a specific ligand. Its modularity enables users to compare different combinations of force fields, rotamer libraries, and scoring functions. Here, we present a much-improved version––PocketOptimizer 2.0. We implemented a cleaner user interface, an extended architecture with more supported tools, such as force fields and scoring functions, a backbone-dependent rotamer library, as well as different improvements in the underlying algorithms. Version 2.0 was tested against a benchmark of design cases and assessed in comparison to the first version. Our results show how newly implemented features such as the new rotamer library can lead to improved prediction accuracy. Therefore, we believe that PocketOptimizer 2.0, with its many new and improved functionalities, provides a robust and versatile environment for the design of small molecule-binding pockets in proteins. It is widely applicable and extendible due to its modular framework. PocketOptimizer 2.0 can be downloaded at https://github.com/Hoecker-Lab/pocketoptimizer .     

Entwicklungsgeschichtliche untersuchungen an einer Blattmutante vonHyoscyamus niger L.

Summary The leaf shape of the mutantfiliformis (fil) ofHyoscyamus niger L. is strongly modified by external factors (like nutrition and light) as well as by the height of insertion. The name filiformis refers to thread-like leaves which always occur in the inflorencence; they may also be formed in the vegetative region, especially under short day conditions. Other leaves may have a small rhombic blade or a larger blade with irregular edges and deep incisions. Even pinnate leaves have been found. In contrast to the leaves of normalHyoscyamus, all mutant leaves (hypsophylls included) have a stalk-like basal portion that seems to be homologous to the basal part of the normal blade. This mutant is caused by one recessive factor which is linked neither toann nor topall.the submarginal initials of the normalHyoscyamus blade were always found dividing according to the periclinal-anticlinal type, while in the mutant the activity of the submarginal initials frequently resulted in a primarily biseriate mesophyll (so-called double-edged segmentation).This is apparently the first time that gene control of the mode of submarginal blade growth has been observed. Further differences between mutant and normalHyoscyamus concern the venation, the lengths of palisade cells and of stomata guard cells, the frequency of stomata per mm², and the thickness of the blade.

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Mit 7 Textabbildungen     

Rindenzellen von Federn im Elektronenmikroskop

Zusammenfassung An Querschnitten von Federästen zweier Vögel (Gallus und Pharomacrus) wurden die Rindenzellen im Elektronenmikroskop untersucht. Sie treten in zwei durch übergänge verbundenen Querschnittsformen auf: einerseits stark abgeplattet mit dichtem Keratinmantel und spaltförmigem Intramoenialraum, andererseits unregelmäßig polygonal umrissen mit Zerklüftung der Tonofibrillenmasse Über das ganze Zellareal hin in grobe Bündel. In beiderlei Zellen verlaufen die Tonofibrillen nach der Länge des Federastes, in Übereinstimmung mit der Aussage der Polarisationsoptik. Die Rindenzellen sind mit Membran bekleidet. An den Grenzen sich berührender Zellen erscheint zwischen den beiden Membranen eine Mittellamelle (central component von Filshie u. Rogers, 1962), die als Kittschicht gedeutet wird, welche die Nachbaren zusammenhält. Auf beiden Seiten der Mittellamelle findet sich eine helle Zone von etwa 8 nm Dicke, die bis zur Membran reicht; ihre Deutung ist fraglich. Die geschilderte Zellgrenzstruktur gilt sowohl für den flächigen Kontakt benachbarter Zellen als auch für die Verzahnung längs aufeinanderfolgender. Verzahnung gibt sich am Zellquerschnitt in der Anwesenheit von rundlichen intrazellulären Arealen zu erkennen, die von der Zellgrenzstruktur umschlossen sind; es handelt sich bei ihnen um Querschnitte von Zellfortsätzen, mit denen die eine Zelle in die andere eindringt.Bei beiden untersuchten Formen finden sich luftführende Melaningranula, über deren Bau später berichtet werden soll.     

A measuring device for calculating electrical impedance of the heart in clinical conditions]

Changes in the electrical impedance of tissue can indicate structural changes. This suggests a technique for the noninvasive detection of allograft rejection after heart transplantation. The direct electrical connection to the heart and the application of a measuring current to the myocardium requires a high standard of safety. A device was developed for measuring cardiac impedance using a sinusoidal current of 20 microA at a frequency of 15 kHz. The control logic ensures a slow current onset and also an immediate cessation in case of conductor fracture or excessive voltage. Initial results in patients with normal recovery after heart transplantation revealed a rapid drop in impedance to about 70% of the initial value in the 1st 48 hours and then a stable course. In the sole rejection episode observed so far, the impedance increased again to 85% of the initial value. This paper discusses the technical safety requirements and the design of the device, and presents initial results of clinical examinations.     

Cell Cycle Timing of Replication of the Nuclear Gene Encoding Chloroplastic NADP-Specific Glutamate Dehydrogenase Isoenzymes in Chlorella sorokiniana

In synchronized Chlorella sorokiniana cells, the NH₄⁺ inducibleNADP-specific glutamate dehydrogenase enzyme (NADP-GDH) accumulatedin a linear manner throughout the first cell cycle. Early inthe following second cell cycle, an increase in its rate ofaccumulation occurred that was proportional to the increasein total cellular DNA in the previous cell cycle. In synchronizedbacterial cells, increases in rate of linear accumulation ofinducible enzymes coincide with the time of replication of theirstructural genes. To determine whether the rate change in NADPGDHaccumulation resulted from a delay in replication of its nuclearstructural gene (gdhN) in fully induced C. sorokiniana cells,the cell cycle timing of replication of this gene was comparedto that of another nuclear gene, nitrate reductase (nia), andof a chloroplast gene, ribulose bisphosphate carboxylase large-subunit(rbcL), in synchronized cells cultured in NH₄⁺ or NO₃^–(uninduced) medium. The gdhN and nia genes replicated withinthe period of nDNA synthesis and rbcL within the period of ctDNAsynthesis in cells growing in either nitrogen source. Therefore,the delayed rate change in enzyme accumulation results froma process that regulates expression of the gdhN gene after itsreplication. (Received July 16, 1994; Accepted November 28, 1994)