Search results for "Fluorescence"

Advances in the Retrieval and Interpretation of Solar-Induced Vegetation Chlorophyll Fluorescence Using Passive Remote Sensing Techniques

2021

In the context of the development and implementation of the Fluorescence Explorer (FLEX) mission, selected in 2015 by the European Space Agency (ESA) as the 8th Earth Explorer, many recent developments in the field of vegetation chlorophyll fluorescence have taken place in the last years. These advances include new retrieval approaches, more accurate and robust, and a much better understanding of the variability of the signal, facilitating the interpretation of the dynamical changes and the usage of the fluorescence signal in Earth models and applications. Although chlorophyll fluorescence is related to the actual photosynthetic activity of the plants, the link between fluorescence and phot…

Mapping and structure of DMXL1, a human homologue of the DmX gene from Drosophila melanogaster coding for a WD repeat protein.

2000

The DmX gene was recently isolated from the X chromosome of Drosophila melanogaster. TBLASTN searches of the dbEST databases revealed sequences with a high level of similarity to DmX in a variety of different species, including insects, nematodes, and mammals showing that DmX is an evolutionarily highly conserved gene. Here we describe the cloning of the cDNA and the chromosomal localization of one of the human homologues of DmX, Dmx-like 1 (DMXL1). The human DMXL1 gene codes for a large mRNA of 11 kb with an open reading frame of 3027 amino acids. The putative protein belongs to the superfamily of WD repeat proteins, which have mostly regulatory functions. The DMXL1 protein contains an exc…

High-performance liquid chromatographic separation of modified and native melittin following transglutaminase-mediated derivatization with a dansyl f…

1991

Abstract The 26-amino acid linear, amphiphilic peptide melittin was enzymatically modified with the fluorescent probe monodansylcadaverine using guinea pig liver transglutaminase and a fluorescent derivative of stoichiometry 1:1 was obtained. Reversed-phase and size-exclusion high-performance liquid chromatographic modes were tested in order to resolve the labelled peptide and native species. The influence of several operational variables was analysed and the elution conditions were optimized so that a satisfactory resolution could be achieved in both instances in a rapid, easy manner. Both chromatographic modes offer the possibility of accurate monitoring of the time course of the enzyme-m…

Identification of a β-Dystroglycan Immunoreactive Subcompartment in Photoreceptor Terminals

2005

PURPOSE Mutations in the dystrophin-associated glycoprotein complex (DGC) cause various forms of muscular dystrophy. These diseases are characterized by progressive loss of skeletal muscle tissue and by dysfunctions in the central nervous system (CNS). The CNS deficits include an altered electroretinogram, caused by an impaired synaptic transmission between photoreceptors and their postsynaptic target cells in the outer plexiform layer (OPL). The DGC is concentrated in the OPL but its exact distribution is controversial. Therefore, the precise distribution of beta-dystroglycan, the central component of the DGC, within the OPL of the mature chick retina, was determined. METHODS Double immuno…

2013

Background To monitor viability of implanted genetically engineered and microencapsulated human stem cells (MicroBeads) in the mouse eye, and to study the impact of the beads and/or xenogenic cells on retinal integrity. Methodology/Principal Findings MicroBeads were implanted into the subretinal space of SV126 wild type mice using an ab externo approach. Viability of microencapsulated cells was monitored by noninvasive retinal imaging (Spectralis™ HRA+OCT). Retinal integrity was also assessed with retinal imaging and upon the end of the study by light and electron microscopy. The implanted GFP-marked cells encapsulated in subretinal MicroBeads remained viable over a period of up to 4 months…

Toward oxygen binding curves of single respiratory proteins

2004

Oxygen binding curves of single molecules promise to discriminate between different models describing cooperativity because load distributions are accessible. Individual tarantula hemocyanins could be detected by fluorescence correlation spectroscopy using intrinsic tryptophan fluorescence as sensor of bound oxygen. However, imaging of immobilized proteins was not possible due to fast photo-bleaching. It is shown that tetra-methyl-carboxy-rhodamine (TAMRA), commonly used as a fluorescence label in single-molecule spectroscopy, can also be applied to monitor bound oxygen. The dye's fluorescence is quenched due to Förster energy transfer to the oxygenated active sites of hemocyanin.

Differential expression and interaction with the visual G-protein transducin of centrin isoforms in mammalian photoreceptor cells.

2004

Photoisomerization of rhodopsin activates a heterotrimeric G-protein cascade leading to closure of cGMP-gated channels and hyperpolarization of photoreceptor cells. Massive translocation of the visual G-protein transducin, Gt, between subcellular compartments contributes to long term adaptation of photoreceptor cells. Ca(2+)-triggered assembly of a centrin-transducin complex in the connecting cilium of photoreceptor cells may regulate these transducin translocations. Here we demonstrate expression of all four known, closely related centrin isoforms in the mammalian retina. Interaction assays revealed binding potential of the four centrin isoforms to Gtbetagamma heterodimers. High affinity b…

Serological evidence for Borna disease virus infection in humans, wild rodents and other vertebrates in Finland

2005

Abstract Background Borna disease virus (BDV) can infect many vertebrate species, including humans. BDV infection may lead to meningoencephalomyelitis in animals. An association with human neuropsychiatric diseases has been reported, but the causal relationship between BDV and human disease remains unclear. Objectives and study design To find out whether BDV is present in Finland and to look for a potential reservoir, we examined a large panel of blood samples from different vertebrate species with immunofluorescence assay. Samples from horses, cats, dogs, sheep, cattle, large predators, grouse, wild rodents and humans were included. Most positive results were confirmed by other specific me…

Expanding the chemical scope of RNA:methyltransferases to site-specific alkynylation of RNA for click labeling.

2010

This work identifies the combination of enzymatic transfer and click labeling as an efficient method for the site-specific tagging of RNA molecules for biophysical studies. A double-activated analog of the ubiquitous co-substrate S-adenosyl-l-methionine was employed to enzymatically transfer a five carbon chain containing a terminal alkynyl moiety onto RNA. The tRNA:methyltransferase Trm1 transferred the extended alkynyl moiety to its natural target, the N2 of guanosine 26 in tRNA(Phe). LC/MS and LC/MS/MS techniques were used to detect and characterize the modified nucleoside as well as its cycloaddition product with a fluorescent azide. The latter resulted from a labeling reaction via Cu(I…

More accuracy to the EROD measurements—The resorufin fluorescence differs between species and individuals

2012

Ethoxyresorufin-O-deethylase (EROD) activity is a biomarker of exposure to planar aromatic hydrocarbons, and it is often measured from the S9 fraction. The effect of the liver S9 fraction of seven boreal freshwater fish species on the fluorescence of resorufin was studied. The S9 fractions diminished resorufin fluorescence by 40–80%, and there were large differences between species. Thus, using a resorufin standard curve without the S9 fraction leads to a large underestimation of the EROD activity. Therefore a microwell plate EROD method was developed that takes into account the effect of each sample on resorufin fluorescence. At least two mechanisms were involved in the decrease of the flu…