Ueber die systematische Stellung desAlyssum Dörfleri m.

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Dynamics of “neuron ring”

Summary Dynamics of neuron ring has been studied by means of computer simulation. The ring is formed of some number of identical neurons which loop together with lateral inhibitions and are stimulated by a command neuron. In this model, we assumed that each neuron has individual activity intrinsically without any inputs. The function of each neuron is essentially the same as that of Reiss' model; each neuron receives one excitatory and two inhibitory signals and when the membrane potential exceeds the instantaneous values of threshold, the neuron fires and sends out signals. Fatigue effect is also introduced in this model; after firing, the threshold level rises up for a period. This report is mainly concerned with the mechanism by which the individual activities of each neuron transit into an ordered behavior as a whole when they are externally stimulated. Results can be summarized as follows: The individual random activities of neurons can be organized and transfered into an ordered behavior on a completely symmetrical neuron ring if externally stimulated and the following conditions are satisfied; 1. the individual inherent activity is within a moderate range, 2. the fatigue effect is large enough, 3. external stimulation is high enough and 4. neurons in the ring are laterally inhibited. The individual activity and the lateral inhibition are essential to generate a meaningful output pattern as a group and fatigue effect acts as a stabilizing factor of the generated pattern.     

Neuere Beobachtungen über die Ursachen der Dörrfleckenkrankheit beim Hafer

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Somatische Mutationen an Flügelschuppen der DörrobstmottePlodia interpunctella Hübner nach Röntgenbestrahlung der Raupen

Ohne ZusammenfassungMit Unterstützung durch die Deutsche Forschungsgemeinschaft. Herrn Dr. A.Wehrmaker danke ich für die Einführung in die praktische Arbeit anPlodia und die Überlassung der Zucht. Herrn Dr.von Woellwarth und Herrn Prof.Krause danke ich für die Unterstützung bei der kritischen Durchsicht des Manuskripts.     

Does “ring syndrome” exist? An analysis of 207 case reports on patients with a ring autosome

Summary Analysis of 207 case reports on patients with ring autosome showed that: (1) Forty patients, a fifth of the total, had extreme growth failure together with an otherwise almost-normal appearance, viz. no major malformation, no specific deletion syndrome, no or only a few unspecific minor anomalies. This phenotype may be regarded as the ring syndrome, a term proposed by Cote et al. (1981) since it is independent of what chromosome is involved. (2) Severe growth failure, the sole major physical abnormality in the ring syndrome, was seen significantly more often among patients with ring of larger chromosomes than among patients with a smaller ring, indicating that the greater the chromosome involved in ring formation, the higher is the probability of severe growth failure. (3) Larger ring chromosomes showed significantly more often instability than smaller rings, suggesting that there may be a correlation between ring instability and the size of the chromosome involved. (4) Growth failure was present in significantly more patients with a labile ring than with a stable ring, indicating that a correlation may exist between ring instability and growth failure. It is suggested that the ring syndrome observed in many cases with ring autosome may result from end-to-end fusion of chromosome ends, an event not involving deletion in the genetic sense. It is also suggested that the ring syndrome is caused by a continuous generation of secondary aneuploid cells with increased mortality, i.e. structural ring instability which seems to be a function of the size of the chromosome involved. Thus, formation of a ring chromosome in certain cases might be regarded as a structural mutation, i.e. an alteration in the structure of the genetic material per se, rather than a loss or gain of genetic dosages.     

Does the 'Ring of Life' ring true?

In a recent stimulating paper, Rivera and Lake applied a new phylogenetic method to study the evolution of genomes, which challenges the classical representation of the Tree of Life. Acknowledging the evolutionary importance of lateral gene transfer, they used the conditioned genome approach to reconstruct the Tree of Life, and in the end proposed a Ring of Life. They explained that the Ring of Life structure is a result of a single fusion event between two prokaryotic genomes at the base of the eukaryotic tree, probably between the ancestors of a photosynthetic bacterium and an archaeon. Because this constitutes an important conclusion with regards to the evolutionary process and origin of the eukaryotic cell, their work deserves further attention before these conclusions can be accepted. Here we question the reconstruction and the meaning of the Ring of Life. In addition to general problems associated with gene-content-based phylogenetic analyses, we discuss some implicit premises and potential weaknesses of the conditioned genome method and conclude that, although Rivera and Lake's conclusions might be right, they have not been established by their current approach.     

ψ-esters of depsidones with a lactole ring

The reaction of stictic, norstictic and salazinic acids with methanol, ethanol and tert-butanol has been investigated. 8′-O-Methylstictic acid is identical with methylstictic acid from Lobaria oregana. Ingolfdottir's vesuvianic acid from Stereocaulon vesuvianum and Handong's cetrariastrumin from Cetrariastrum nepalensis have been shown to be 8′-O-ethylstictic acid and 8′,9′-di-O-ethylsalazinic acid, respectively, by reaction of stictic and salazinic acids with ethanol.     

Chromosome cohesion: ring around the sisters?

Sister chromatid cohesion is a key aspect of accurate chromosome transmission during mitosis, yet little is known about the structure of cohesin, the protein complex that links the two sister chromatids. Recent studies shed light on the structure of the cohesin complex, leading to intriguing models that could explain how sister chromatids are held together.     

Die von J. Dörfler im Jahre 1904 auf Kreta gesammelten Moose

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Standortsuntersuchungen und Neufunde vonHalacsya sendtneri (Boiss.)Dörfl. in Bosnien

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Studien über eine kleine,endemische Bevölkerung in Dänemark

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RINGS — a general program to build ring systems

RINGS is a computer program for the general and rapid construction of ring skeletons. Prestored molecules are connected together by various operations, such as joining along one bond, fusion of one or more bonds, spiro joining, and carbon-bridge building. RINGS uses full 3D molecular structure information from the outset and offers the user full control of all geometrical features at each step of construction. The program is user-friendly, with a graphical man-machine interface (PLOT10-compatible) and extensive checking for possible input errors.     

γ-Tubulin ring complexes regulate microtubule plus end dynamics

γ-Tubulin is critical for the initiation and regulation of microtubule (MT) assembly. In Drosophila melanogaster, it acts within two main complexes: the γ-tubulin small complex (γ-TuSC) and the γ-tubulin ring complex (γ-TuRC). Proteins specific of the γ-TuRC, although nonessential for viability, are required for efficient mitotic progression. Until now, their role during interphase remained poorly understood. Using RNA interference in Drosophila S2 cells, we show that the γ-TuRC is not critical for overall MT organization. However, depletion of any component of this complex results in an increase of MT dynamics. Combined immunofluorescence and live imaging analysis allows us to reveal that the γ-TuRC localizes along interphase MTs and that distal γ-tubulin spots match with sites of pause or rescue events. We propose that, in addition to its role in nucleation, the γ-TuRC associated to MTs may regulate their dynamics by limiting catastrophes.