Adenosine A1 receptor activation mediates the developmental shift at layer 5 pyramidal cell synapses and is a determinant of mature synaptic strength

During the first postnatal month glutamatergic synapses between layer 5 pyramidal cells in the rodent neocortex switch from an immature state exhibiting high probability of neurotransmitter release, large unitary amplitude and synaptic depression to a mature state with decreased probability of release, smaller unitary amplitude and synaptic facilitation. Using paired recordings, we demonstrate that the developmental shift in release probability at synapses between rat somatosensory layer 5 thick-tufted pyramidal cells is due to a higher and more heterogeneous activation of presynaptic adenosine A1 receptors. Immature synapses under control conditions exhibited distributions of CV, failure rate and release probability that were almost coincident with the A1 receptor blocked condition; however, mature synapses under control conditions exhibited much broader distributions that spanned those of both the A1 receptor agonised and antagonised conditions. Immature and mature synapses expressed A1 receptors with no observable difference in functional efficacy and therefore the heterogeneous A1 receptor activation seen in the mature neocortex is due to increased adenosine concentrations that vary between synapses. Given the central role demonstrated for A1 receptor activation in determining synaptic amplitude and the statistics of transmission between mature layer 5 pyramidal cells, the emplacement of adenosine sources and sinks near the synaptic terminal could constitute a novel form of long-term synaptic plasticity

Visfatin reduces gap junction mediated cell-to-cell communication in proximal tubule-derived epithelial cells

Background/Aims: In the current study we examined if the adipocytokine, visfatin, alters connexin-mediated intercellular communication in proximal tubule-derived epithelial cells. Methods: The effects of visfatin (10-200ng/mL) on cell viability and cytotoxicity in HK2-cells were assessed by MTT, crystal violet and lactate dehydrogenase assays. Western blot analysis was used to confirm expression of Cx26, Cx40 and Cx43. The effect of visfatin (10-200ng/mL) on TGF-β1 secretion was confirmed by ELISA, and the effects of both TGF-β1 (2-10ng/mL) and visfatin (10-200ng/mL) on connexin expression were assessed by western blot. Functional intercellular communication was determined using transfer of Lucifer Yellow and paired-whole cell patch clamp electrophysiology. Results: In low glucose (5mM), visfatin (10-200ng/mL) did not affect membrane integrity, cytotoxicity or cell viability at 48hrs, but did evoke a concentration-dependent reduction in Cx26 and Cx43 expression. The expression of Cx40 was unaffected. At 48hrs, visfatin (10-200ng/mL) increased the secretion of TGF-β1 and the visfatin-evoked changes in connexin expression were mimicked by exogenous application of the pro-fibrotic cytokine (2-10ng/ml). Visfatin reduced dye transfer between coupled cells and decreased functional conductance, with levels falling by 63% as compared to control. Although input resistance was increased following visfatin treatment by 166%, the change was not significant as compared to control. The effects of visfatin on Cx-expression and cell-coupling were blocked in the presence of a TGF-β1 specific neutralizing antibody. Conclusions: The adipocytokine visfatin selectively evoked a non-toxic reduction in connexin expression in HK2-cells. The loss in gap-junction associated proteins was mirrored by a loss in functional conductance between coupled cells. Visfatin increased TGF-β secretion and the pattern of change for connexins expression was mimicked by exogenous application of TGF-β1. The effect of visfatin on Cx-expression and dye transfer were negated in the presence of a TGF-β1 neutralising antibody. These data suggest that visfatin reduces connexin-mediated intercellular communication in proximal tubule-derived epithelial cells via a TGF-β dependent pathway. © 2013 S. Karger AG, Base

Visfatin reduces gap junction mediated cell-to-cell communication in proximal tubule-derived epithelial cells

Aim: Associated with obesity, visfatin may have a role in the pathogenesis of diabetic nephropathy in type II diabetes. This study identifies a link between the visfatin, TGF-β1 and reduced cell-to-cell coupling in proximal tubule derived epithelial cells. Methods: Western blot analysis confirmed changes in expression of connexins Cx26, Cx40 and Cx43 in HK2-cells +/- visfatin &/or TGF-β1. Visfatin evoked increases in TGF-β1 secretion were determined by ELISA, and functional intercellular communication assessed via Lucifer yellow dye transfer and paired-whole cell patch clamp electrophysiology. Results: Visfatin (10, 100 and 200ng/mL) decreased expression of Cx26 to 58±11%, 40± 3% and 21±2% and Cx43 to 73±5%, 44± 4% and 29±6% as compared to control at 48hrs (n=3; P<0.01). The effects were not dependent on changes in membrane integrity, cytotoxicity or cell viability as assessed by MTT, crystal-violet and lactate-dehydrogenase assays. Expression of Cx40 was unaffected by the adipocytokine. Visfatin (200ng/ml) increased TGF-β1 secretion by 154% of control (n=3; p<0.01). Visfatin-evoked changes in Cx26 and Cx43 expression were mimicked by exogenous application of TGF-β1 (2-10ng/ml, p<0.001 n=3). Visfatin reduced dye transfer between coupled-cells and decreased functional conductance by 63% as compared to control (n=6; p<0.01). Conclusions: Visfatin reduced connexin expression in HK2-cells, an effect mirrored by a loss in functional conductance between coupled cells. Visfatin increased TGF-β secretion and the pattern of change for connexin expression was mimicked by exogenous application of the pro-fibrotic cytokine. These data suggest that visfatin reduces connexin-mediated intercellular communication in proximal tubule-derived epithelial cells via a TGF-β dependent pathway. This work is supported by a grant from Diabetes UK (BDA: 11/0004215)

Framing Ethnic Variations in Alcohol Outcomes from Biological Pathways to Neighborhood Context

Background Health disparities research seeks to eliminate disproportionate negative health outcomes experienced in some racial/ethnic minority groups. This brief review presents findings on factors associated with drinking and alcohol‐related problems in racial/ethnic groups. Methods Those discussed are as follows: (i) biological pathways to alcohol problems, (ii) gene × stress interactions, (iii) neighborhood disadvantage, stress, and access to alcohol, and (iv) drinking cultures and contexts. Results These factors and their interrelationships are complex, requiring a multilevel perspective. Conclusions The use of interdisciplinary teams and an epigenetic focus are suggested to move the research forward. The application of multilevel research to policy, prevention, and intervention programs may help prioritize combinations of the most promising intervention targets

Gene capture prediction and overlap estimation in EST sequencing from one or multiple libraries

BACKGROUND: In expressed sequence tag (EST) sequencing, we are often interested in how many genes we can capture in an EST sample of a targeted size. This information provides insights to sequencing efficiency in experimental design, as well as clues to the diversity of expressed genes in the tissue from which the library was constructed. RESULTS: We propose a compound Poisson process model that can accurately predict the gene capture in a future EST sample based on an initial EST sample. It also allows estimation of the number of expressed genes in one cDNA library or co-expressed in two cDNA libraries. The superior performance of the new prediction method over an existing approach is established by a simulation study. Our analysis of four Arabidopsis thaliana EST sets suggests that the number of expressed genes present in four different cDNA libraries of Arabidopsis thaliana varies from 9155 (root) to 12005 (silique). An observed fraction of co-expressed genes in two different EST sets as low as 25% can correspond to an actual overlap fraction greater than 65%. CONCLUSION: The proposed method provides a convenient tool for gene capture prediction and cDNA library property diagnosis in EST sequencing

ChloroplastDB: the Chloroplast Genome Database

The Chloroplast Genome Database (ChloroplastDB) is an interactive, web-based database for fully sequenced plastid genomes, containing genomic, protein, DNA and RNA sequences, gene locations, RNA-editing sites, putative protein families and alignments (). With recent technical advances, the rate of generating new organelle genomes has increased dramatically. However, the established ontology for chloroplast genes and gene features has not been uniformly applied to all chloroplast genomes available in the sequence databases. For example, annotations for some published genome sequences have not evolved with gene naming conventions. ChloroplastDB provides unified annotations, gene name search, BLAST and download functions for chloroplast encoded genes and genomic sequences. A user can retrieve all orthologous sequences with one search regardless of gene names in GenBank. This feature alone greatly facilitates comparative research on sequence evolution including changes in gene content, codon usage, gene structure and post-transcriptional modifications such as RNA editing. Orthologous protein sets are classified by TribeMCL and each set is assigned a standard gene name. Over the next few years, as the number of sequenced chloroplast genomes increases rapidly, the tools available in ChloroplastDB will allow researchers to easily identify and compile target data for comparative analysis of chloroplast genes and genomes

Identification of shared single copy nuclear genes in Arabidopsis, Populus, Vitis and Oryza and their phylogenetic utility across various taxonomic levels

<p>Abstract</p> <p>Background</p> <p>Although the overwhelming majority of genes found in angiosperms are members of gene families, and both gene- and genome-duplication are pervasive forces in plant genomes, some genes are sufficiently distinct from all other genes in a genome that they can be operationally defined as 'single copy'. Using the gene clustering algorithm MCL-tribe, we have identified a set of 959 single copy genes that are shared single copy genes in the genomes of <it>Arabidopsis thaliana, Populus trichocarpa, Vitis vinifera </it>and <it>Oryza sativa</it>. To characterize these genes, we have performed a number of analyses examining GO annotations, coding sequence length, number of exons, number of domains, presence in distant lineages, such as <it>Selaginella </it>and <it>Physcomitrella</it>, and phylogenetic analysis to estimate copy number in other seed plants and to demonstrate their phylogenetic utility. We then provide examples of how these genes may be used in phylogenetic analyses to reconstruct organismal history, both by using extant coverage in EST databases for seed plants and <it>de novo </it>amplification via RT-PCR in the family Brassicaceae.</p> <p>Results</p> <p>There are 959 single copy nuclear genes shared in <it>Arabidopsis</it>, <it>Populus</it>, <it>Vitis </it>and <it>Oryza </it>["APVO SSC genes"]. The majority of these genes are also present in the <it>Selaginella </it>and <it>Physcomitrella </it>genomes. Public EST sets for 197 species suggest that most of these genes are present across a diverse collection of seed plants, and appear to exist as single or very low copy genes, though exceptions are seen in recently polyploid taxa and in lineages where there is significant evidence for a shared large-scale duplication event. Genes encoding proteins localized in organelles are more commonly single copy than expected by chance, but the evolutionary forces responsible for this bias are unknown.</p> <p>Regardless of the evolutionary mechanisms responsible for the large number of shared single copy genes in diverse flowering plant lineages, these genes are valuable for phylogenetic and comparative analyses. Eighteen of the APVO SSC single copy genes were amplified in the Brassicaceae using RT-PCR and directly sequenced. Alignments of these sequences provide improved resolution of Brassicaceae phylogeny compared to recent studies using plastid and ITS sequences. An analysis of sequences from 13 APVO SSC genes from 69 species of seed plants, derived mainly from public EST databases, yielded a phylogeny that was largely congruent with prior hypotheses based on multiple plastid sequences. Whereas single gene phylogenies that rely on EST sequences have limited bootstrap support as the result of limited sequence information, concatenated alignments result in phylogenetic trees with strong bootstrap support for already established relationships. Overall, these single copy nuclear genes are promising markers for phylogenetics, and contain a greater proportion of phylogenetically-informative sites than commonly used protein-coding sequences from the plastid or mitochondrial genomes.</p> <p>Conclusions</p> <p>Putatively orthologous, shared single copy nuclear genes provide a vast source of new evidence for plant phylogenetics, genome mapping, and other applications, as well as a substantial class of genes for which functional characterization is needed. Preliminary evidence indicates that many of the shared single copy nuclear genes identified in this study may be well suited as markers for addressing phylogenetic hypotheses at a variety of taxonomic levels.</p

Drivers of success in implementing sustainable tourism policies in urban areas

The existing literature in the field of sustainable tourism highlights a number of barriers that impede the implementation of policies in this area. Yet, not many studies have so far considered the factors that would contribute to putting this concept into practice, and few address the case of urban areas. The concept of sustainability has only received limited attention in urban tourism research, even though large cities are recognised as one of the most important tourist destinations that attract vast numbers of visitors. Adopting a case study approach, this paper discusses a number of drivers of success identified by policy-makers in London to contribute to the implementation of sustainable tourisms policies at the local level, and briefly looks at the relationship between these drivers and the constraints perceived by the respondents to hinder the implementation of such policies in practice. These findings may help policy-makers in other large cities to successfully develop and implement policies towards sustainable development of tourism in their area

The Amborella genome: an evolutionary reference for plant biology

The nuclear genome sequence of Amborella trichopoda, the sister species to all other extant angiosperms, will be an exceptional resource for plant genomics