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T Mayr

Publications and source records attributed to T Mayr.

12 recordsLinked to original sources
PubMed2006

Filter cubes with built-in ultrabright light-emitting diodes as exchangeable excitation light sources in fluorescence microscopy.

The use of ultrabright light-emitting diodes as a potential substitute for conventional excitation light sources in fluorescence microscopy is demonstrated. We integrated ultrabright light-emitting diodes in the filter block of a conventional fluorescence microscope together with a collimating Fresnel lens, a holographic diffuser and emission filters. This setup enabled convenient changes between different excitation light sources and resulted in high excitation efficiencies. Quantitative comparison of image intensities of test samples revealed that light-emitting diodes yielded intensities in the range of a mercury arc lamp depending on the wavelength. The use of ultrabright light-emitting diodes also enabled luminescence lifetime imaging without the need for image intensification.

Journal Article↗
PubMed2001

Fluorimetric determination of copper(II) in aqueous solution using lucifer yellow CH as selective metal reagent.

Lucifer yellow CH is shown to be a highly selective fluorescent reagent for the determination of Cu(III) in the microg L(-1) concentration range. The fluorophore is statically quenched by Cu(II); the carbohydrazide group was assigned as the complexing part of the dye molecule. A total range of Cu(II) determination from 0.06 mg L(-1) (1 micromol L(-1)) to 6.3 mg L(-2) (100 micromol L(-1)) with a limit of detection of 0.019 mg L(-1) (0.3 micromol L(-1)) was obtained, along with surprisingly high selectivity. There was no interference from alkaline and earth alkaline metal ions. The cross sensitivity to heavy metal ions was evaluated by the separate solution method and by competitive binding experiments. Calibration plots are shown for Cu(II) determination at different pH and the dissociation constant was determined. The application of the reagent was demonstrated by the determination of the Cu(II) content of tap water samples.

Journal Article↗
PubMed2000

Cloning and characterization of zebrafish smad2, smad3 and smad4.

smad genes encode transcription factors involved in the signal transduction of members of the TGFbeta superfamily. We report here the cloning, characterization and genomic mapping of smad2, smad3 and smad4 from the zebrafish, Danio rerio. In Xenopus, smad2 overexpression has been shown to interfere with gastrulation and dorsal cell fate specification. However, full-length zebrafish smad2, although functionally active in Xenopus explants, has no effect when overexpressed in zebrafish embryos. In contrast, an N-terminally truncated, constitutively active version of Smad2 protein causes severe dorsalization or partial secondary axis formation, pointing to a role of Smad2 during mesoderm and axis formation. The temporal and spatial expression patterns of zebrafish smad2, 3 and 4 were investigated by developmental RT-PCR and whole mount in-situ hybridization. All three genes show strong and ubiquitous maternal expression. Zygotic expression is weak and ubiquitous in the case of smad2, and strong and ubiquitious in the case of smad4, while smad3 shows a spatially restricted zygotic expression pattern. It is expressed in migrating neural crest cells of the trunk and a subset of cells in the diencephalon in close proximity to the expression domain of the Nodal-related protein Cyclops/Ndr2/Znr1, a potential signal upstream of Smad2/3 required for eye-field separation and floor plate specification. Overexpression of truncated smad2 in cyclops mutant embryos leads to a rescue of the eye and floorplate defects. These data suggest that Smad2 acts as a mediator of Nodal signals during zebrafish midline signaling, while Smad3 might be involved in later steps of eye field separation.

Amino Acid Sequence↗
PubMed1997

Fritz: a secreted frizzled-related protein that inhibits Wnt activity.

Signaling molecules of the Wnt gene family are involved in the regulation of dorso-ventral, segmental and tissue polarity in Xenopus and Drosophila embryos. Members of the frizzled gene family, such as Drosophila frizzled-2 and rat frizzled-1, have been shown encode Wnt binding activity and to engage intracellular signal transduction molecules known to be part of the Wnt signaling pathway. Here we describe the cloning and characterization of Fritz, a mouse (mfiz) and human (hfiz) gene which codes for a secreted protein that is structurally related to the extracellular portion of the frizzled genes from Drosophila and vertebrates. The Fritz protein antagonizes Wnt function when both proteins are ectopically expressed in Xenopus embryos. In early gastrulation, mouse fiz mRNA is expressed in all three germ layers. Later in embryogenesis fiz mRNA is found in the central and peripheral nervous systems, nephrogenic mesenchyme and several other tissues, all of which are sites where Wnt proteins have been implicated in tissue patterning. We propose a model in which Fritz can interfere with the activity of Wnt proteins via their cognate frizzled receptors and thereby modulate the biological responses to Wnt activity in a multitude of tissue sites.

Amino Acid Sequence↗
PubMed1992

[Stability of shy-anxious-inhibited behavior in kindergarten children].

The stability of internalizing disorders was studied over a period of 15 months in a sample of three- to five-year-old children attending preschool (N = 280). Stability coefficients for shyness/inhibition (rT1-T2 = .65/.77), oversensitivity (rT1-T2 = .49/.69) and dependency (rT1-T2 = .43/.64) showed a high to moderate (normative) continuity during this stage of development. There were no sex differences but there were significant age variations: The stability of shyness/inhibition was about twice as high in the oldest cohort as in the youngest age group. Persistence of internalizing behavior dimensions was much stronger in a withdrawn-aggressive group than in a withdrawn-nonaggressive group. Peer status had some predictive utility, but for the sample as a whole there was only a low correlation between sociometric variables (T1) and internalizing scores (T2); the level of correlation was strongly dependent on the children's age and sex.

Aggression↗
PubMed1989

[Handicapped children and children at risk for handicaps in Bavarian integrated kindergartens--initial results of a survey].

The survey "integrative preschool education - an inquiry in Bavarian preschools/kindergartens" aimed to obtain a representative picture of the situation of handicapped children in regular preschool settings - as opposed to special institutions. In this paper we present information regarding distribution among different group-sizes as well as different defining/diagnosing systems. We also investigated the influence of certain ecological conditions such as size of place where the preschool is situated and distance between preschool and the nearest special institution. Furthermore we gained insight into the conditions which hinder and those which promote the admission of handicapped children.

Child, Preschool↗
PubMedDate not supplied

Optical sensor for seawater salinity.

An optical sensor for the measurement of salinity in seawater has been developed. It is based on a chloride-quenchable fluorescent probe (lucigenin) immobilized on a Nafion film. Two approaches for measuring salinity via chloride concentration are presented. In the first, a change in salinity corresponds to a change in the fluorescence intensity of lucigenin. In the second, the fluorescence intensity information is converted into a phase angle information by adding an inert phosphorescent reference luminophore (a ruthenium complex entrapped in poly(acrylonitrile) beads). Under these conditions, the chloride-dependent fluorescence intensity of lucigenin can be converted into a chloride-dependent fluorescence phase shift which serves as the analytical information. This scheme is referred to as dual lifetime referencing (DLR). The sensor was used to determine the salinity in seawater and brackish water of the North Sea.

Journal Article↗