Introduction Gap junctions are dynamically modulated bridges allowing the transcellular passage of ions and small molecules with a molecular mass of up to 1 kDa, a mechanism utilized for molecular communication purposes by living cells. This same mechanism is also exploited by scientists to reveal the existence of gap junction contacts by the cell-to-cell movement of tracers. However, multiple labeling experiments require the availability of multiple gap junction-permeable tracers. Methods To this end, we utilized the well-known transient OFF alpha retinal ganglion cell (RGC)-coupled array as a model system to study and compare the transjunctional movement of neurobiotin (NB), a commonly used tracer, and serotonin, a recently identified tracer. Results Although the transjunctional movement of serotonin has been established in cell cultures, here we show, for the first time, that serotonin is also a potent tracer in in vitro tissue. In addition, serotonin is lighter than the classical gap junction-permeable NB, and thus, we expected that tracer movement would be comparable to or better than that of serotonin. We found that intracellular serotonin injections result in the labeling of the coupled transient OFF alpha RGC array very similar to those of the classical NB-labeled arrays. Both serotonin and NB-injected transient OFF alpha RGCs displayed the well-known pattern with coupled RGCs and a cohort of coupled wide-field amacrine cells (ACs). Discussion By using morphological characteristics, we confirm that the serotonin and the NB-coupled AC arrays are identical, and thereby confirm that serotonin is a potent gap junction-permeable tracer and can be readily used as an alternative to NB in in vitro tissue. Moreover, serotonin can be utilized in parallel with other dyes or tracers, enabling the use of multiple labels in the same material.

Gap junctions (GJs) are not static bridges; instead, GJs as well as the molecular building block connexin (Cx) proteins undergo major expression changes in the degenerating retinal tissue. Various progressive diseases, including retinitis pigmentosa, glaucoma, age-related retinal degeneration, etc., affect neurons of the retina and thus their neuronal connections endure irreversible changes as well. Although Cx expression changes might be the hallmarks of tissue deterioration, GJs are not static bridges and as such they undergo adaptive changes even in healthy tissue to respond to the ever-changing environment. It is, therefore, imperative to determine these latter adaptive changes in GJ functionality as well as in their morphology and Cx makeup to identify and distinguish them from alterations following tissue deterioration. In this review, we summarize GJ alterations that take place in healthy retinal tissue and occur on three different time scales: throughout the entire lifespan, during daily changes and as a result of quick changes of light adaptation.

The goal of the study was to evaluate the pollen spectrum, antioxidant capacity and mineral content of four Hungarian honey types, using multivariate statistical analysis. The light colored honeys were represented by milkweed honey and a multifloral (MF) honey with dominant pollen frequency of linden (MF-Tilia); the darker ones were goldenrod honey and a multifloral honey with Lamiaceae pollen majority (MF-Lamiaceae). The pollen spectrum of the samples was established with melissopalynological analysis. The absorbance of the honeys positively correlated with the antioxidant capacity determined with three of the used methods (TRC, TEAC, DPPH), but not with ORAC. The latter method correlated negatively also with other antioxidant methods and with most of the mineral values. MF-Tilia had high ORAC value, K and Na content. The MF-Lamiaceae had the highest K, Mg, P, S, Cu and Zn content, the last five elements showing strict correlation with the TRC method. The darker goldenrod honey had higher SET values and total mineral content, than the milkweed honey. The above character-sets facilitate identification of each honey type and serve as indicators of variety. The antioxidant levels and mineral content of honeys allowed their clear separation by principal component analysis (PCA).

Retinal ganglion cells (RGCs) encrypt stimulus features of the visual scene in action potentials and convey them toward higher visual centers in the brain. Although there are many visual features to encode, our recent understanding is that the ~46 different functional subtypes of RGCs in the retina share this task. In this scheme, each RGC subtype establishes a separate, parallel signaling route for a specific visual feature (e.g., contrast, the direction of motion, luminosity), through which information is conveyed. The efficiency of encoding depends on several factors, including signal strength, adaptational levels, and the actual efficacy of the underlying retinal microcircuits. Upon collecting inputs across their respective receptive field, RGCs perform further analysis (e.g., summation, subtraction, weighting) before they generate the final output spike train, which itself is characterized by multiple different features, such as the number of spikes, the inter-spike intervals, response delay, and the rundown time (transience) of the response. These specific kinetic features are essential for target postsynaptic neurons in the brain in order to effectively decode and interpret signals, thereby forming visual perception. We review recent knowledge regarding circuit elements of the mammalian retina that participate in shaping RGC response transience for optimal visual signaling.

Vision is our primary sense as the human eye is the gateway for more than 65% of information reaching the human brain. Today’s increased exposure to different wavelengths and intensities of light from light emitting diode (LED) sources could induce retinal degeneration and accompanying neuronal cell death. Damage induced by chronic phototoxic reactions occurring in the retina accumulates over years and it has been suggested as being responsible for the etiology of many debilitating ocular conditions. In this work, we examined how LED stimulation affects vision by monitoring changes in the expression of death and survival factors as well as microglial activation in LED-induced damage (LID) of the retinal tissue. We found an LED-exposure-induced increase in the mRNA levels of major apoptosis-related markers BAX, Bcl-2, and Caspase-3 and accompanying widespread microglial and Caspase-3 activation. Everyday LED light exposure was accounted for in all the described changes in the retinal tissue of mice in this study, indicating that overuse of non-filtered direct LED light can have detrimental effects on the human retina as well.

ABSTRACT The compound eye of the fruit fly Drosophila melanogaster is one of the most intensively studied and best understood model organs in the field of developmental genetics. Herein we demonstrate that autophagy, an evolutionarily conserved selfdegradation process of eukaryotic cells, is essential for eye development in this organism. Autophagic structures accumulate in a specific pattern in the developing eye disc, predominantly in the morphogenetic furrow (MF) and differentiation zone. Silencing of several autophagy genes (Atg) in the eye primordium severely affects the morphology of the adult eye through triggering ectopic cell death. In Atg mutant genetic backgrounds however genetic compensatory mechanisms largely rescue autophagic activity in, and thereby normal morphogenesis of, this organ. We also show that in the eye disc the expression of a key autophagy gene, Atg8a, is controlled in a complex manner by the anterior Hox paralog Lab (Labial), a master regulator of early development. Atg8a transcription is repressed in front of, while activated along, the MF by Lab. The amount of autophagic structures then remains elevated behind the moving MF. These results indicate that eye development in Drosophila depends on the cell death-suppressing and differentiating effects of the autophagic process. This novel, developmentally regulated function of autophagy in the morphogenesis of the compound eye may shed light on a more fundamental role for cellular self-digestion in differentiation and organ formation than previously thought. Abbreviations: αTub84B, α-Tubulin at 84B; Act5C, Actin5C; AO, acridine orange; Atg, autophagy-related; Ato, Atonal; CASP3, caspase 3; Dcr-2; Dicer-2; Dfd, Deformed; DZ, differentiation zone; eGFP, enhanced green fluorescent protein; EM, electron microscopy; exd, extradenticle; ey, eyeless; FLP, flippase recombinase; FRT, FLP recognition target; Gal4, gene encoding the yeast transcription activator protein GAL4; GFP, green fluorescent protein; GMR, Glass multimer reporter; Hox, homeobox; hth, homothorax; lab, labial; L3F, L3 feeding larval stage; L3W, L3 wandering larval stage; lf, loss-of-function; MAP1LC3, microtubule-associated protein 1 light chain 3; MF, morphogenetic furrow; PE, phosphatidylethanolamine; PBS, phosphate-buffered saline; PI3K/PtdIns3K, class III phosphatidylinositol 3-kinase; PZ, proliferation zone; Ref(2)P, refractory to sigma P, RFP, red fluorescent protein; RNAi, RNA interference; RpL32, Ribosomal protein L32; RT-PCR, reverse transcription-coupled polymerase chain reaction; S.D., standard deviation; SQSTM1, Sequestosome-1, Tor, Target of rapamycin; TUNEL, terminal deoxynucleotidyl transferase mediated dUTP nick end labeling assay; UAS, upstream activation sequence; qPCR, quantitative real-time polymerase chain reaction; w, white

DNA methylation is a decisive regulator of gene expression. Differentially methylated promoters were described in rheumatoid arthritis (RA), but we do not know how these epimutations can trigger a proinflammatory cytokine milieu. B cell-focused DNA methylome studies identified a group of genes that had undergone disease-associated changes in a murine model of RA. An arthritis-specific epimutation (hypomethylation) was detected in the promoter region of the Zbtb38 gene, which encodes a transcriptional repressor. Gene expression studies revealed that hypomethylation of the Zbtb38 promoter was accompanied by disease-specific repressor expression, and two anti-inflammatory factors interleukin 1 receptor 2 gene (IL1r2) and interleukin-1 receptor antagonist (IL1rn) were among the downregulated genes. We hypothesized that Zbtb38 repressor could induce downregulated expression of these anti-inflammatory genes and that this could significantly contribute to arthritis pathogenesis. Our studies demonstrate that Zbtb38 forms a molecular bridge between an arthritis-associated epimutation (DNA hypomethylation in Zbtb38 promoter) and transcriptional silencing of the IL1r2 gene in B cells. In this way, disease-associated DNA hypomethylation can support autoimmune arthritis by interfering with an anti-inflammatory pathway.

Objective: Disease- and drug-related biomarkers are the basis of personalized medicine by guiding patient-specific clinical decisions. The methylene-tetrahydrofolate reductase (MTHFR) gene-associated C677T polymorphism has garnered particular attention because it can lead to an amino acid change resulting in a catalytically compromised enzyme. Here, we provide an alternative interpretation of C677T-associated MTHFR phenotypes that does not exclude the original hypothesis but rather places it in a different context. Our duon-based theory has practical implications as it facilitates the development of a new predictive biomarker for Rheumatoid Arthritis (RA) and Systemic Lupus Erythematosus (SLE).Methods: The new MTHFR promoter was identified using the 5’RACE method and functionally characterized in transient expression studies. Western blotting and confocal microscopy were used to investigate the subcellular localization of MTHFR isoforms. Expression of MTHFR transcript variants was monitored by qRT-PCR and a gene expression index (Li/Si score) was calculated from the Ct values.Results: A new MTHFR isoform was identified, driven by a novel promoter region that overlaps with the site of the C677T polymorphism. Quantitative monitoring of the catalytically active and the catalytically inactive isoforms’ expression revealed that the proportion of MTHFR isoforms could be altered in PBMCs in a disease-specific manner. The calculated Li/Si scores were found to be characteristic for specific subgroups of RA and SLE patients.Conclusion: Differential expression of MTHFR isoforms provides a foundation on which a predictive biomarker (Li/Si score) could be developed for RA and SLE reflecting disease susceptibility and drug response.

The effects of population bottlenecks, from both the population and conservation genetics point of view, have attracted great interest. Heterozygosity and allelic diversity are basic components of the evolutionary potential of populations. Many endangered species go through bottlenecks from time to time. The consequences are important because in the resulting small populations the stochastic processes are more pronounced and, by strengthening each other, they can lead to extinction. Within the framework of the global climate change the question emerges of how the different species, primarily susceptible ones and those depending on protection measures, react to the climate extremities. It is well known that a large proportion of Barn Owl Tyto alba populations die following an unfavourable period. In the study reported here we genotyped 24 microsatellite loci of 58 unrelated Barn Owl individuals originating from a continuous population of three neighbouring Hungarian counties. We then performed the Wilcoxon sign-rank test, the L test and Monte Carlo simulation of the loss of alleles and heterozygosity. We also attempted to infer past population dynamics using two likelihood-based Bayesian methods. Although a 74% reduction of this population is well documented following the harsh winter of 2002/2003 and the sampling and resolution of the methods used are standard and considered to be commonly satisfactory, none of the tests showed pronounced signs of a recent bottleneck. These results are discussed in terms of the imminent and apparent drawbacks of the models and methods used, the roles of absolute numbers of survivors versus genotype percentages and the conservation biological viewpoint.

ObjectiveTo identify epigenetic factors that are implicated in the pathogenesis of rheumatoid arthritis (RA), and to explore the therapeutic potential of the targeted inhibition of these factors.MethodsPolymerase chain reaction (PCR) arrays were used to investigate the expression profile of genes that encode key epigenetic regulator enzymes. Mononuclear cells from RA patients and mice were monitored for gene expression changes, in association with arthritis development in murine models of RA. Selected genes were further characterized by quantitative reverse transcription-PCR, Western blot, and flow cytometry methods. The targeted inhibition of the up-regulated enzymes was studied in arthritic mice.ResultsA set of genes with arthritis-specific expression was identified by the PCR arrays. Aurora kinases A and B, both of which were highly expressed in arthritic mice and treatment-naive RA patients, were selected for detailed analysis. Elevated aurora kinase expression was accompanied by increased phosphorylation of histone H3, which promotes proliferation of T lymphocytes. Treatment with VX-680, a pan-aurora kinase inhibitor, promoted B cell apoptosis, provided significant protection against disease onset, and attenuated inflammatory reactions in arthritic mice.ConclusionArthritis development is accompanied by changes in expression of a number of epigenome-modifying enzymes. Drug-induced down-regulation of the aurora kinases, among other targets, seems to be sufficient to treat experimental arthritis. Development of new therapeutics that target aurora kinases can potentially improve RA management.

Morphological and functional changes of cells are important for adapting to environmental changes and associated with continuous regulation of gene expressions. Genes are regulated–in part–by epigenetic mechanisms resulting in alternating patterns of gene expressions throughout life. Epigenetic changes responding to the environmental and intercellular signals can turn on/off specific genes, but do not modify the DNA sequence. Most epigenetic mechanisms are evolutionary conserved in eukaryotic organisms, and several homologs of epigenetic factors are present in plants and animals. Moreover, in vitro studies suggest that the plant cytoplasm is able to induce a nuclear reassembly of the animal cell, whereas others suggest that the ooplasm is able to induce condensation of plant chromatin. Here, we provide an overview of the main epigenetic mechanisms regulating gene expression and discuss fundamental epigenetic mechanisms and factors functioning in both plants and animals. Finally, we hypothesize that animal genome can be repro-grammed by epigenetic factors from the plant protoplast.

Former studies have shown that the Great Reed Warbler ( Acrocephalus arundinaceus ) has two genetically distinguishable haplogroups (a “western” and an “eastern” clade). The species occurs in South Africa from January to late March, yet, in the whole database of EURING, there are no recoveries to the south of the Congo. There are at least three hypotheses concerning which birds are seen wintering in South Africa: (1) the European breeders reach South Africa, but there are no ringing recoveries; (2) a mixed population of birds originating from Turkey, Iran and Kazakhstan (Near and Middle East) winters in South Africa; and (3) birds from Europe and the Near and Middle Eastern populations both reach South Africa. We have sequenced a 492-bp part of the mtDNA control region II in 146 samples from five European breeding and one South African wintering population of Great Reed Warblers. The results show that over 60% of the wintering birds in South Africa carry European haplotypes, belonging to both “eastern” and “western” clades. Since the exact haplotypic constitution of the Near and Middle Eastern populations are not known to us, we cannot exclude that a mixed wintering population is formed from birds originating from these regions, but it seems more likely that the European breeders reach South Africa.

Ringing databases of the EURING Data Bank and the Hungarian Bird Ringing Centre were analysed in order to investigate the philopatry of the great reed warbler ( Acrocephalus arundinaceus ) in three European regions. The aim of the study was to find out if there are continent-scale geographic trends in philopatry with respect to the age of the birds. Three clusters were assigned according to their geographic positions: (i) southern part of Europe (Region 1: between 36°–43° latitudes), (ii) middle part of Europe (Region 2: between 43°–49° latitudes) and (iii) northern part of Europe, (Region 3: between 49°–56° latitudes). No significant differences were found between the natal and breeding philopatry in any Regions, except Region 3. The birds ringed as adults in Region 3 were less faithful to their breeding site than those of the other two regions. Natal philopatry of juveniles did not differ between Region 1 and Region 2, but both of them differed in this respect from Region 3. A method for choosing appropriate breeding periods in philopatry studies is also proposed.

We have identified 15 polymorphic microsatellite loci for the barn owl (Tyto alba), five from testing published owl loci and 10 from testing non-owl loci, including loci known to be of high utility in passerines and shorebirds. All 15 loci were sequenced in barn owl, and new primer sets were designed for eight loci. The 15 polymorphic loci displayed two to 26 alleles in 56-58 barn owls. When tested in 10 other owl species (n = 1-6 individuals), between four and nine loci were polymorphic per species. These loci are suitable for studies of population structure and parentage in owls.

In Baranya County (Southern Hungary), tawny owls (Strix aluco) and barn owls (Tyto alba) sequentially use the same nest boxes in a significant number of cases. A total of 460 broods were observed between 1996 and 2003 and, in 12 cases, whole broods of dead tawny owl chicks were registered that had apparently been killed. On investigating the reproductive life characteristics, population sizes, and frequency of killing in these two species, it was concluded that: (1) with growing barn owl population, the number of sequential broods increases but changes in tawny owl population size have no effect on the frequency of sequential broods; (2) the number of killings depends on the number of sequential broods; and (3) with growing barn owl population, the number of killings also grows and this change is unaffected by the size of the tawny owl population. However, no killing occurs as long as 50-60% of the nest boxes are unoccupied. There is no killing either until the percentage of nest boxes occupied by barn owls reaches 40%, although a threshold value like this cannot be shown for the tawny owl. In the cases when a barn owl breeding follows the tawny owl's, the percentage of killing is significantly higher compared to that when barn owls do not breed in the same box. These results indicate that barn owls kill the offspring of tawny owls. By these means, they obtain a breeding place earlier than without killing the chicks of the other species, and this results in higher reproductive success. (c) 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95, 488-494.

Hoszu tavu celunk, hogy megertsuk a szimbiotikus nitrogenkotő gumő kifejlődeset, es azonositsuk az invazioban fontos bakterialis geneket. E palyazatban feladatunk volt, hogy (i) elemezzuk azon rkp geneket, melyek a Sinorhizobium meliloti 41 torzs specifikus KR5 kapszularis poliszacharidjanak bioszinteziseben vesznek reszt, (ii) meghatarozzuk pontos funkciojat a pha geneknek, melyekről felteteleztuk, hogy a pH-homeosztazisban fontosak. Fagreceptorban hibas bakterium es host range fag mutansok molekularis genetikai elemzese reven kimutattuk, hogy a 16-3 fag receptoranak fontos alkotoja az RkpM feherje, es azonositottuk a fag h genjet, mely a farki rost feherjet kodolja. A KR5 antigenről kimutattuk, hogy csak a szimbiotikus gumő invaziojakor fontos, de nem alkotoja a fagreceptornak. Befejeztuk a DNS-szekvencia meghatarozast az rkp-3 regioban, es vizsgaltuk az azonositott genek szerepet. Egyes es kettős rkpY mutansok segitsegevel, amelyekben a masodik mutacio kulonboző rkp genekben volt kimutattuk, hogy (i) az rkpY mutansok altal termelt poliszacharid nem prekurzora a KR5 antigennek, es hogy (ii) az rkpR gen ennek az uj poliszacharidnak a bioszinteziseben jatszik szerepet. A pha genek szerepet kiforditott membran vezikulakon vegzett fiziologiai kiserletekben vizsgaltuk. Kimutattuk, hogy a K+ adas proton kiaramlast eredmenyez, ami alatamasztja korabbi feltetelezesunket, hogy e genek egy K+/H+ antiportert kodolnak. | Our long term goal is to understand the development of nitrogen fixing symbiotic nodule and to identify bacterial genes involved in the invasion. In this project we focus on (i) the analysis of the rkp genes involved in the biosynthesis of the strain specific KR5 polysaccharide of Sinorhizobium meliloti 41, and (ii) analysis of function of pha gene clusters presumed to be important in pH-homeostasis. The molecular genetic analysis of phage receptor bacterial and host-range phage mutants resulted in the identification of the RkpM protein as an essential part of the 16-3 phage receptor, and in the identification of h gene of the phage encoding the tail-fiber protein. The KR5 antigen were shown only to be important in the invasion of symbiotic nodule but not in the structure of phage receptor. DNA-sequence analysis of the rkp-3 region was completed and the role of the identified genes were examined. Using single and double rkpY mutants, where the second mutations were in different rkp genes, it was shown that (i) the polysaccharide produced by the rkpY mutant was not a precursor of the KR5 antigen, (ii) the rkpR gene is involved in the synthesis of this new polysaccharide. The role of the pha genes were examined on everted membrane vesicles. It was shown that addition of K+ results in proton efflux supporting our hypothesis that pha genes encode for a K+/H+ antiporter.

The white Barn Owl subspecies (Tyto alba alba) is found in southern Europe and the reddish-brown subspecies (T a. guttata) in northern and eastern Europe. In central Europe, the two subspecies interbreed producing a large range of phenotypic variants. Because of the different ratios of the subspecies in different geographic regions, we predict that genetic variation should be greater in Switzerland than in Hungary. We tested this hypothesis by measuring genetic variation with the RAPD method. As predicted, the genetic differentiation within a Swiss population of Barn Owls was significantly greater than the variation within a Hungarian population. This suggests that gene flow is greater in central Europe than at the eastern limit of the Barn Owl distribution in Hungary. In both countries genetic variation was more pronounced in females than in males. As in other birds, this is probably because female Barn Owls are less philopatric than males. The number of migrants between Hungary and Switzerland is ca. 1 individual per generation; if calculated separately for the sexes, then 0.525 for males and ca. I for females (Nm values). The difference in the number of migrants between genders again is likely a consequence of higher male philopatry. The sexual differentiation is greater in the Swiss population than in the Hungarian and the genetic substructuring of the populations of the species is substantial. The reason for the considerable population substructuring could be the nonmigratory behavior and socially monogamous pairing of the species, as well as the geographical barriers (Alps) between the populations examined.

ABSTRACT The strain-specific capsular polysaccharide KR5 antigen of Sinorhizobium meliloti 41 is required both for invasion of the symbiotic nodule and for the adsorption of bacteriophage 16-3 . In order to know more about the genes involved in these events, bacterial mutants carrying an altered phage receptor were identified by using host range phage mutants. A representative mutation was localized in the rkpM gene by complementation and DNA sequence analysis. A host range phage mutant isolated on these phage-resistant bacteria was used to identify the h gene, which is likely to encode the tail fiber protein of phage 16-3 . The nucleotide sequences of the h gene as well as a host range mutant allele were also established. In both the bacterial and phage mutant alleles, a missense mutation was found, indicating a direct contact between the RkpM and H proteins in the course of phage adsorption. Some mutations could not be localized in these genes, suggesting that additional components are also important for bacteriophage receptor recognition.

The colouration of the underparts of the Barn Owl ranges in Europe from reddish-brown to white. This character, that shows a clinal variation, is thought to be a marker of subspecies identity. The subspecific identity or transitional state of a total 64 Barn Owl Tyto alba pairs was determined on the basis of their phenotypic characteristics. The present authors investigated the breadth of the transition zone in Hungary on the basis of the distribution of the white-chested subspecies and the transitional phenotype, and it was found to be at least 500 km wide. The width of the transition zone may result from the lack of preferences in mating pair choice. The observed pattern of phenotypic distribution is due to the marginal location of the studied population in the transition zone.