NK and T cells constitute two major, functionally distinct intestinal epithelial lymphocyte subsets in the chicken

Non-mammalian NK cells have not been characterized in detail; however, their analysis is essential for the understanding of the NK cell receptor phylogeny. As a first step towards defining chicken NK cells, several tissues were screened for the presence of NK cells, phenotypically defined as CD8(+) cells lacking T- or B-lineage specific markers. By this criteria, approximately 30% of CD8(+) intestinal intraepithelial lymphocytes (IEL), but <1% of splenocytes or peripheral blood lymphocytes were defined as NK cells. These CD8(+)CD3(-) IEL were used for the generation of the 28-4 mAb, immunoprecipitating a 35-kDa glycoprotein with a 28-kDa protein core. The CD3 and 28-4 mAb were used to separate IEL into CD3(+) IEL T cells and 28-4(+) cells, both co-expressing the CD8 antigen. During ontogeny, 28-4(+) cells were abundant in the IEL and in the embryonic spleen, where two subsets could be distinguished according to their CD8 and c-kit expression. Most importantly, 28-4(+) IEL lysed NK-sensitive targets, whereas intestinal T cells did not have any spontaneous cytolytic activity. These results define two major, phenotypically and functionally distinct IEL subpopulations, and imply an important role of NK cells in the mucosal immune system

More on the universal equation for Efimov states

Efimov states are a sequence of shallow three-body bound states that arise when the two-body scattering length is much larger than the range of the interaction. The binding energies of these states are described as a function of the scattering length and one three-body parameter by a transcendental equation involving a universal function of one angular variable. We provide an accurate and convenient parametrization of this function. Moreover, we discuss the effective treatment of range corrections in the universal equation and compare with a strictly perturbative scheme.Comment: 13 pages, 5 figure

Application of Cathodoluminescence in Paint Analysis

When solving cases of burglary or investigating ship collisions, the forensic scientist frequently has to examine several layers of paint of the same color, often white. As a rule, the usual microscopic and spectroscopic methods [fluorescence microscopy, FT-IR (Fourier Transform Infrared Spectroscopy), pyrolysis, GC/MS (Gas Chromatography - Mass Spectrometry), etc.] are not sufficient to prove that the paint traces found on the scene, which are often only available in the form of fragments, originated from the same source as the reference material. It is possible to achieve convincing proof of this using either an optical cathodoluminescence-microscope or a cathodoluminescence-scanning electron microscope, both of which can be coupled to a visible (VIS)-spectrometer

Cytokines of Birds: Conserved Functions

Targeted disruptions of the mouse genes for cytokines, cytokine receptors, or components of cytokine signaling cascades convincingly revealed the important roles of these molecules in immunologic processes. Cytokines are used at present as drugs to fight chronic microbial infections and cancer in humans, and they are being evaluated as immune response modifiers to improve vaccines. Until recently, only a few avian cytokines have been characterized, and potential applications thus have remained limited to mammals. Classic approaches to identify cytokine genes in birds proved difficult because sequence conservation is generally low. As new technology and high throughput sequencing became available, this situation changed quickly. We review here recent work that led to the identification of genes for the avian homologs of interferon-a/b (IFNa/b) and IFN-g, various interleukins (IL), and several chemokines. From the initial data on the biochemical properties of these molecules, a picture is emerging that shows that avian and mammalian cytokines may perform similar tasks, although their primary structures in most cases are remarkably different

Chicken BAFF

Members of the tumor necrosis factor (TNF) family play key roles in the regulation of inflammation, immune responses and tissue homeostasis. Here we describe the identification of the chicken homologue of mammalian B cell activating factor of the TNF family (BAFF/BLyS). By searching a chicken EST database we identified two overlapping cDNA clones that code for the entire open reading frame of chicken BAFF (chBAFF), which contains a predicted transmembrane domain and a putative furin protease cleavage site like its mammalian counterparts. The amino acid identity between soluble chicken and human BAFF is 76%, considerably higher than for most other known cytokines. The chBAFF gene is most strongly expressed in the bursa of Fabricius. Soluble recombinant chBAFF produced by human 293T cells interacted with the mammalian cell-surface receptors TACI, BCMA and BAFF-R. It bound to chicken B cells, but not to other lymphocytes, and it promoted the survival of splenic chicken B cells in culture. Furthermore, bacterially expressed chBAFF induced the selective expansion of B cells in the spleen and cecal tonsils when administered to young chicks. Our results suggest that like its mammalian counterpart, chBAFF plays an important role in survival and/or proliferation of chicken B cells

Identification of a Candidate CD5 Homologue in the Amphibian Xenopus laevis

We identified a novel T cell Ag in the South African clawed toad (Xenopus laevis) by a mAb designated 2B1. This Ag is present in relatively high levels on most thymocytes, approximately 65% of splenocytes, 55% of PBL, and 65% of intestinal lymphocytes, but is rarely seen on IgM+ B cells in any of these tissues. Lymphocytes bearing the 2B1 Ag proliferate in response to stimulation with Con A or PHA, whereas the 2B1- lymphocytes are reactive to LPS. Biochemical analysis indicates that this Ag is a differentially phosphorylated glycoprotein of 71 to 82 kDa. The protein core of 64 kDa bears both N- and O-linked carbohydrate side chains. The amino-terminal protein sequence of the 2B1 Ag shares significant homology with both the macrophage scavenger receptor type 1 motif and the mammalian CD5/CD6 family. The biochemical characteristics and cellular distribution of the 2B1 Ag suggest that it represents the CD5 homologue in X. laevis. While T cells constitutively express this highly conserved molecule, Xenopus B cells acquire the CD5 homologue only when they are stimulated in the presence of T cell

Identification of T-cell receptor a-chain genes in the chicken

T-cell receptor (TCR) -chain (TCR) and ß-chain (TCRß) genes are well characterized in mammals, while only TCRß genes have been identified in other vertebrates. To identify avian TCR genes, we used monoclonal anti-CD3 antibodies to isolate chicken TCR for peptide sequence analysis. Degenerate oligonucleotide probes were then used to isolate a candidate TCR cDNA clone that hybridized with a 1.7-kb mRNA species present only in ß T cells and in tissues populated by these cells. Southern blot analysis revealed gene rearrangement in thymocytes and ß T-cell lines. The TCR cDNA candidate encoded an openreading frame of 275 amino acids, the predicted variable (V)-, joining (J)-, and constant (C)-region amino acid sequences of which shared 40%, 60%, and 25% homology with corresponding mammalian sequences. A single C gene and 25 V genes were identified by using region-specific probes. The V cDNA probe isolated from a Vß1+ cell line reacted with transcripts from one of five Vß2+ cell lines, suggesting shared use of V genes by Vß1+ and Vß2+ T cells and the existence of other V gene families. A genomic V sequence was flanked by classical recombination signal sequences but, unlike previously defined V genes, the leader and V region were encoded by a single exon. The data indicate evolutionary conservation of the basic TCR gene structure in birds and mammal

The neural correlates of semantic richness : Evidence from an fMRI study of word learning

We investigated the neural correlates of concrete nouns with either many or few semantic features. A group of 21 participants underwent two days of training and were then asked to categorize 40 newly learned words and a set of matched familiar words as living or nonliving in an MRI scanner. Our results showed that the most reliable effects of semantic richness were located in the left angular gyrus (AG) and middle temporal gyrus (MTG), where activation was higher for semantically rich than poor words. Other areas showing the same pattern included bilateral precuneus and posterior cingulate gyrus. Our findings support the view that AG and anterior MTG, as part of the multimodal network, play a significant role in representing and integrating semantic features from different input modalities. We propose that activation in bilateral precuneus and posterior cingulate gyrus reflects interplay between AG and episodic memory systems during semantic retrieval

Stochastic optimization of a cold atom experiment using a genetic algorithm

We employ an evolutionary algorithm to automatically optimize different stages of a cold atom experiment without human intervention. This approach closes the loop between computer based experimental control systems and automatic real time analysis and can be applied to a wide range of experimental situations. The genetic algorithm quickly and reliably converges to the most performing parameter set independent of the starting population. Especially in many-dimensional or connected parameter spaces the automatic optimization outperforms a manual search.Comment: 4 pages, 3 figure

Time-resolved measurements of fluorescence from reaction centres of Rhodopseudomonas viridis and the effect of menaquinone reduction

AbstractThe kinetics of the fluorescence emitted by the ‘special pair’ of bacteriochlorophyll b molecules in reaction centres from Rhodopseudomonas viridis was recorded in the near infrared, with a time resolution of 1 ns. In nonreduced reaction centres two decay components were resolved with lifetimes of <0.5 and 2.5 ns. Upon reduction of the menaquinone electron acceptor three decay components were detected with lifetimes of < 0.5, 2.5 and 15ns