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Publication
Journal: Journal of Cell Science
April/25/2005
Abstract
The effect of trichostatin A (TSA)-induced histone acetylation on the interphase chromatin structure was visualized in vivo with a HeLa cell line stably expressing histone H2A, which was fused to enhanced yellow fluorescent protein. The globally increased histone acetylation caused a reversible decondensation of dense chromatin regions and led to a more homogeneous distribution. These structural changes were quantified by image correlation spectroscopy and by spatially resolved scaling analysis. The image analysis revealed that a chromatin reorganization on a length scale from 200 nm to >1 microm was induced consistent with the opening of condensed chromatin domains containing several Mb of DNA. The observed conformation changes could be assigned to the folding of chromatin during G1 phase by characterizing the effect of TSA on cell cycle progression and developing a protocol that allowed the identification of G1 phase cells on microscope coverslips. An analysis by flow cytometry showed that the addition of TSA led to a significant arrest of cells in S phase and induced apoptosis. The concentration dependence of both processes was studied.
Publication
Journal: Biochimica et Biophysica Acta - General Subjects
March/19/1985
Abstract
A cytochrome c-551 and a pair of 'high redox-potential' ferredoxins (iso-high-potential iron-sulfur proteins) were found to be the major soluble electron-transport proteins in Ectothiorhodospira halophila. Smaller amounts of 'bacterial' ferredoxin and cytochrome c' were also observed. With the exception of cytochrome c-551, these proteins are commonly encountered in the purple sulfur bacteria, family Chromatiaceae and less frequently in the purple bacteria, family Rhodospirillaceae. In addition to the cytochromes and ferredoxins, E. halophila synthesizes substantial amounts of a small yellow-colored protein, which has a chromophore spectrally similar to flavins having oxygen, nitrogen or sulfur substituents in place of the 8-methyl group such as roseoflavin and the methanogen cofactor F-420. A purple-colored protein was only partially purified, but it is spectrally similar to iron proteins having a tyrosine ligand, such as transferrin, catechuate dioxygenase, and especially the purple acid phosphatases. Neither the yellow protein nor the purple one has previously been observed in phototrophic bacteria, but may in some way be required for survival in extremely halophilic habitats. The only feature common to halophiles including E. halophila is the very acidic nature of their proteins.
Authors
Publication
Journal: PLoS Pathogens
January/4/2012
Abstract
West Nile (WNV), dengue (DENV) and yellow fever (YFV) viruses are (re)emerging, mosquito-borne flaviviruses that cause human disease and mortality worldwide. Alterations in mosquito gene expression common and unique to individual flaviviral infections are poorly understood. Here, we present a microarray analysis of the Aedes aegypti transcriptome over time during infection with DENV, WNV or YFV. We identified 203 mosquito genes that were ≥ 5-fold differentially up-regulated (DUR) and 202 genes that were ≥ 10-fold differentially down-regulated (DDR) during infection with one of the three flaviviruses. Comparative analysis revealed that the expression profile of 20 DUR genes and 15 DDR genes was quite similar between the three flaviviruses on D1 of infection, indicating a potentially conserved transcriptomic signature of flaviviral infection. Bioinformatics analysis revealed changes in expression of genes from diverse cellular processes, including ion binding, transport, metabolic processes and peptidase activity. We also demonstrate that virally-regulated gene expression is tissue-specific. The overexpression of several virally down-regulated genes decreased WNV infection in mosquito cells and Aedes aegypti mosquitoes. Among these, a pupal cuticle protein was shown to bind WNV envelope protein, leading to inhibition of infection in vitro and the prevention of lethal WNV encephalitis in mice. This work provides an extensive list of targets for controlling flaviviral infection in mosquitoes that may also be used to develop broad preventative and therapeutic measures for multiple flaviviruses.
Publication
Journal: Free Radical Biology and Medicine
September/27/2007
Abstract
Extensive research within the past half-century has indicated that curcumin (diferuloylmethane), a yellow pigment in curry powder, exhibits antioxidant, anti-inflammatory, and proapoptotic activities. We investigated whether the anti-inflammatory and proapoptotic activities assigned to curcumin are mediated through its prooxidant/antioxidant mechanism. We found that TNF-mediated NF-kappaB activation was inhibited by curcumin; and glutathione reversed the inhibition. Similarly, suppression of TNF-induced AKT activation by curcumin was also abrogated by glutathione. The reducing agent also counteracted the inhibitory effects of curcumin on TNF-induced NF-kappaB-regulated antiapoptotic (Bcl-2, Bcl-xL, IAP1), proliferative (cyclin D1), and proinflammatory (COX-2, iNOS, and MMP-9) gene products. The suppression of TNF-induced AP-1 activation by curcumin was also reversed by glutathione. Also, the direct proapoptotic effects of curcumin were inhibited by glutathione and potentiated by depletion of intracellular glutathione by buthionine sulfoximine. Moreover, curcumin induced the production of reactive oxygen species and modulated intracellular GSH levels. Quenchers of hydroxyl radicals, however, were ineffective in inhibiting curcumin-mediated NF-kappaB suppression. Further, N-acetylcysteine partially reversed the effect of curcumin. Based on these results we conclude that curcumin mediates its apoptotic and anti-inflammatory activities through modulation of the redox status of the cell.
Publication
Journal: Journal of General Virology
April/30/2017
Abstract
The Flaviviridae is a family of small enveloped viruses with RNA genomes of 9000-13 000 bases. Most infect mammals and birds. Many flaviviruses are host-specific and pathogenic, such as hepatitis C virus in the genus Hepacivirus. The majority of known members in the genus Flavivirus are arthropod borne, and many are important human and veterinary pathogens (e.g. yellow fever virus, dengue virus). This is a summary of the current International Committee on Taxonomy of Viruses (ICTV) report on the taxonomy of the Flaviviridae, which is available at www.ictv.global/report/flaviviridae.
Publication
Journal: PLoS Pathogens
February/13/2012
Abstract
DNA methylation is a fundamental epigenetic modification that regulates gene expression and represses endogenous transposons and invading DNA viruses. As a counter-defense, the geminiviruses encode proteins that inhibit methylation and transcriptional gene silencing (TGS). Some geminiviruses have acquired a betasatellite called DNA β. This study presents evidence that suppression of methylation-mediated TGS by the sole betasatellite-encoded protein, βC1, is crucial to the association of Tomato yellow leaf curl China virus (TYLCCNV) with its betasatellite (TYLCCNB). We show that TYLCCNB complements Beet curly top virus (BCTV) L2⁻ mutants deficient for methylation inhibition and TGS suppression, and that cytosine methylation levels in BCTV and TYLCCNV genomes, as well as the host genome, are substantially reduced by TYLCCNB or βC1 expression. We also demonstrate that while TYLCCNB or βC1 expression can reverse TGS, TYLCCNV by itself is ineffective. Thus its AC2/AL2 protein, known to have suppression activity in other geminiviruses, is likely a natural mutant in this respect. A yeast two-hybrid screen of candidate proteins, followed by bimolecular fluorescence complementation analysis, revealed that βC1 interacts with S-adenosyl homocysteine hydrolase (SAHH), a methyl cycle enzyme required for TGS. We further demonstrate that βC1 protein inhibits SAHH activity in vitro. That βC1 and other geminivirus proteins target the methyl cycle suggests that limiting its product, S-adenosyl methionine, may be a common viral strategy for methylation interference. We propose that inhibition of methylation and TGS by βC1 stabilizes geminivirus/betasatellite complexes.
Publication
Journal: Molecular Plant Pathology
June/18/2017
Abstract
Genome editing in plants has been boosted tremendously by the development of CRISPR/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats) technology. This powerful tool allows substantial improvement in plant traits in addition to those provided by classical breeding. Here, we demonstrate the development of virus resistance in cucumber (Cucumis sativus L.) using Cas9/subgenomic RNA (sgRNA) technology to disrupt the function of the recessive eIF4E (eukaryotic translation initiation factor 4E) gene. Cas9/sgRNA constructs were targeted to the N' and C' termini of the eIF4E gene. Small deletions and single nucleotide polymorphisms (SNPs) were observed in the eIF4E gene targeted sites of transformed T1 generation cucumber plants, but not in putative off-target sites. Non-transgenic heterozygous eif4e mutant plants were selected for the production of non-transgenic homozygous T3 generation plants. Homozygous T3 progeny following Cas9/sgRNA that had been targeted to both eif4e sites exhibited immunity to Cucumber vein yellowing virus (Ipomovirus) infection and resistance to the potyviruses Zucchini yellow mosaic virus and Papaya ring spot mosaic virus-W. In contrast, heterozygous mutant and non-mutant plants were highly susceptible to these viruses. For the first time, virus resistance has been developed in cucumber, non-transgenically, not visibly affecting plant development and without long-term backcrossing, via a new technology that can be expected to be applicable to a wide range of crop plants.
Publication
Journal: Current Opinion in Plant Biology
November/28/2006
Abstract
Compared to other organisms, plants have expanded families of transporters that are involved in the uptake and efflux of metals. Fortunately, in many cases, the examination of double mutants has been sufficient to overcome the challenge of studying functionally redundant gene families. Plants that lack two heavy-metal-transporting P-type ATPase family members (HMA2 and HMA4) reveal a function for these transporters in Zn translocation from roots to shoots. Likewise, the phenotype of plants that lack two natural resistance associated macrophage protein (NRAMP) homologs (NRAMP3 and NRAMP4) implicate these metal uptake proteins in the mobilization of vacuolar Fe stores during seed germination. Most families of metal transporters are ubiquitous but the Yellow Stripe1-Like (YSL) family is plant specific and YSL family members have been implicated in the transport of metals that are complexed with a plant specific chelator called nicotianamine (NA).
Publication
Journal: Proceedings of the National Academy of Sciences of the United States of America
September/27/2009
Abstract
Maintenance of genome stability is essential for the accurate propagation of genetic information and cell growth and survival. Organisms have therefore developed efficient strategies to prevent DNA lesions and rearrangements. Much of the information concerning these strategies has been obtained through the study of bacterial and nuclear genomes. Comparatively, little is known about how organelle genomes maintain a stable structure. Here, we report that the plastid-localized Whirly ssDNA-binding proteins are required for plastid genome stability in Arabidopsis. We show that a double KO of the genes AtWhy1 and AtWhy3 leads to the appearance of plants with variegated green/white/yellow leaves, symptomatic of nonfunctional chloroplasts. This variegation is maternally inherited, indicating defects in the plastid genome. Indeed, in all variegated lines examined, reorganized regions of plastid DNA are amplified as circular and/or head-tail concatemers. All amplified regions are delimited by short direct repeats of 10-18 bp, strongly suggesting that these regions result from illegitimate recombination between repeated sequences. This type of recombination occurs frequently in plants lacking both Whirlies, to a lesser extent in single KO plants and rarely in WT individuals. Maize mutants for the ZmWhy1 Whirly protein also show an increase in the frequency of illegitimate recombination. We propose a model where Whirlies contribute to plastid genome stability by protecting against illegitimate repeat-mediated recombination.
Publication
Journal: Plant Cell
February/18/2017
Abstract
Seed coat color in soybean is determined by four alleles of the classically defined / (inhibitor) locus that controls the presence or absence as well as the spatial distribution of anthocyanin pigments in the seed coat. By analyzing spontaneous mutations of the / locus, we demonstrated that the / locus is a region of chalcone synthase (CHS) gene duplications. Paradoxically, deletions of CHS gene sequences allow higher levels of CHS mRNAs and restore pigmentation to the seed coat. The unusual nature of the / locus suggests that its dominant alleles may represent naturally occurring examples of homology-dependent gene silencing and that the spontaneous deletions erase the gene-silencing phenomena. Specifically, mutations from the dominant ii allele (yellow seed coats with pigmented hila) to the recessive i allele (fully pigmented) can be associated with the absence of a 2.3-kb Hindlll fragment that carries CHS4, a member of the multigene CHS family. Seven independent mutations exhibit deletions in the CHS4 promoter region. The dominant / allele (yellow seed coats) exhibits an extra 12.1-kb Hindlll fragment that hybridizes with both the CHS coding region and CHS1 promoter-specific probes. Mutations of the dominant / allele to the recessive i allele (pigmented seed coats) give rise to 10.4- or 9.6-kb Hindlll CHS fragments that have lost the duplicated CHS1 promoter. Finally, gene expression analysis demonstrated that heterozygous plants (I/i) with yellow seed coats have reduced mRNA levels, indicating that the 12.1-kb Hindlll CHS fragment associated with the dominant / allele inhibits pigmentation in a trans-dominant manner. Moreover, CHS gene-specific expression in seed coats shows that multiple CHS genes are expressed in seed coats.
Publication
Journal: Histochemistry
March/7/1990
Abstract
Polarization colors of various purified collagens were studied in fibers of similar thickness. Three different soluble collagens of type I, insoluble collagen type I, lathyritic collagen type I, two p-N-collagens type I, pepsin extract collagen type II, two soluble collagens type III, p-N-collagen type III, and soluble collagen type V were submitted to a routine histopathologic procedure of fixation, preparation of 5-microns-thick sections, staining with Picrosirius red and examination under crossed polars. Polarization colors were determined for thin fibers (0.8 micron or less) an thick fibers, (1.6-2.4 microns). Most thin fibers of collagens and p-N-collagens showed green to yellowish-green polarization colors with no marked differences between the various samples. Thick fibers of all p-N-collagens, lathyritic and normal 0.15 M NaCl-soluble collagens showed green to greenish-yellow polarization colors, while in all other collagens, polarization colors of longer wavelengths (from yellowish-orange to red) were observed. These data suggested that fiber thickness was not the only factor involved in determining the polarization colors of Picrosirius red-stained collagens. Tightly packed and presumably, better aligned collagen molecules showed polarization colors of longer wavelengths. Thus, packing of collagen molecules and not only fiber thickness plays a role in the pattern of polarization colors of Picrosirius red-stained collagens.
Publication
Journal: Journal of Cell Science
May/1/2005
Abstract
Annexin 2 is a Ca(2+)-regulated membrane protein and an F-actin-binding protein enriched at actin assembly sites both, on the plasma membrane and on endosomal vesicles. Here, we identify annexin 2 as a phosphatidylinositol (4,5)-bisphosphate (PtdIns(4,5)P(2))-interacting protein, thereby explaining this specific membrane association. Using the pleckstrin-homology (PH) domain of phospholipase Cdelta1 fused to yellow fluorescent protein as a marker for PtdIns(4,5)P(2), we show that annexin 2 and its ligand p11 (S100A10) are targeted to sites of PtdIns(4,5)P(2) enrichment where F-actin accumulates. At the plasma membrane, adhesion of pedestal-forming enteropathogenic Escherichia coli induces a recruitment of 1-phosphatidylinositol-4-phosphate 5-kinase (PtdIns4P 5-kinase) and an enrichment of PtdIns(4,5)P(2) and annexin 2-p11 at sites of bacterial adhesion. Induction of PtdIns(4,5)P(2)-enriched ruffles and PtdIns(4,5)P(2)-positive, actin-coated vacuoles by Arf6-mediated activation of PtdIns4P 5-kinase also leads to a concomitant accumulation of the annexin 2-p11 complex and the PH domain. Binding studies with immobilized phosphoinositides and phosphoinositide-containing liposomes reveal that the purified annexin 2-p11 complex directly and specifically binds to PtdIns(4,5)P(2) with an affinity comparable to that of the PH domain of phospholipase Cdelta1. Experiments using individual subunits identify annexin 2 as the PtdIns(4,5)P(2)-binding entity. Thus, the direct interaction of annexin 2 with PtdIns(4,5)P(2) is a means of specifically recruiting the annexin 2-p11 complex to sites of membrane-associated actin assembly.
Publication
Journal: Proceedings of the National Academy of Sciences of the United States of America
June/29/2010
Abstract
We constructed a 9.9-kilobase cloning vector, designated pKBY2, for isolating genes by complementation of mutations in Aspergillus nidulans. pKBY2 contains the bacteriophage lambda cos site, to permit in vitro assembly of phage particles; a bacterial origin of replication and genes for resistance to ampicillin and chloramphenicol, to permit propagation in Escherichia coli; the A. nidulans trpC(+) gene, to permit selection in Aspergillus; and a unique BamHI restriction site, to permit insertion of DNA fragments produced by digestion with restriction endonucleases BamHI, BglII, Mbo I, or Sau3A. We used this cosmid to form a quasirandom recombinant DNA library containing 35- to 40-kilobase DNA fragments from a wild-type strain of A. nidulans. DNA from this library transformed a yellow-spored (yA(-)) pabaA(-)trpC(-)Aspergillus strain (FGSC237) to trpC(+) at frequencies of approximately 10 transformants per mug of DNA. Three of approximately 1000 trpC(+)pabaA(-) colonies obtained were putative yA(+) transformants, because they produced wild-type (green) spores. DNA from each of the green-spored transformants contained pKBY2 sequences and DNA from two transformants transduced E. coli to ampicillin resistance following treatment in vitro with a lambda packaging extract. The cosmids recovered in E. coli had similar restriction patterns and both yielded trpC(+) transformants of A. nidulans FGSC237, 85% of which produced green spores. Several lines of evidence indicate that the recovered cosmids contain a wild-type copy of the yA gene.
Publication
Journal: Journal of Virology
June/10/2008
Abstract
We report here the construction of a triply fluorescent-tagged herpes simplex virus 1 (HSV-1) expressing capsid protein VP26, tegument protein VP22, and envelope protein gB as fusion proteins with monomeric yellow, red, and cyan fluorescent proteins, respectively. The recombinant virus enabled us to monitor the dynamics of these capsid, tegument, and envelope proteins simultaneously in the same live HSV-1-infected cells and to visualize single extracellular virions with three different fluorescent emissions. In Vero cells infected by the triply fluorescent virus, multiple cytoplasmic compartments were found to be induced close to the basal surfaces of the infected cells (the adhesion surfaces of the infected cells on the solid growth substrate). Major capsid, tegument, and envelope proteins accumulated and colocalized in the compartments, as did marker proteins for the trans-Golgi network (TGN) which has been implicated to be the site of HSV-1 secondary envelopment. Moreover, formation of the compartments was correlated with the dynamic redistribution of the TGN proteins induced by HSV-1 infection. These results suggest that HSV-1 infection causes redistribution of TGN membranes to form multiple cytoplasmic compartments, possibly for optimal secondary envelopment. This is the first real evidence for the assembly of all three types of herpesvirus proteins-capsid, tegument, and envelope membrane proteins-in TGN.
Publication
Journal: Journal of Cell Science
December/14/1992
Abstract
Although coated vesicles can mediate both solute and receptor-mediated endocytosis, there are other kinds of endocytic vesicles that contribute to these processes. The relative contributions of these other organelles, particularly regarding solute influx, remains unsettled. Here we describe a physiological uncoupling of solute and receptor-mediated endocytosis that occurs during growth factor-stimulated macropinocytosis. We examined how recombinant human macrophage colony-stimulating factor (rM-CSF), which rapidly stimulates solute endocytosis in murine bone marrow-derived macrophages, affected ligand internalization via receptor-mediated endocytosis. Although rM-CSF stimulated internalization and accumulation of Lucifer Yellow (LY), a probe for solute endocytosis, it had no effect on accumulation of fluorescent acetylated low-density lipoprotein (acLDL), a ligand for the macrophage scavenger receptor, or on the endocytosis of 125I-labelled diferric transferrin. Video microscopy revealed that rM-CSF immediately induced active cell ruffling and the formation of phase-bright macropinosomes. Nocodazole pretreatment of macrophages inhibited both ruffling and macropinocytosis. Macropinosomes were fluorescently labelled by incubating macrophages briefly with probes for both solute endocytosis (fluorescent dextrans) and ligand endocytosis (fluorescein-labelled transferrin or diI-labelled acLDL). Macrophages incubated for one or two minutes formed macropinosomes that were labelled predominantly with the fluorescent solute probes but with little or none of the ligand probes; the latter were localized within smaller pinosomes. When cells pulsed with the fluorescent probes were washed and chased for an additional two minutes, solute and ligand probes occasionally co-localized in macropinosomes. Nocodazole inhibited macropinocytosis with little apparent effect on endocytosis via smaller vesicles. These experiments show that macropinosome formation is dependent on microtubules and also that the macropinosomes induced by rM-CSF are solute-rich and receptor-poor. Macropinosomes differ from coated vesicles in these respects, and therefore provide a physiologically regulated mechanism for uncoupling solute and receptor-mediated endocytosis.
Publication
Journal: Gastroenterology
October/25/2005
Abstract
OBJECTIVE
Epithelial cells of the small intestine migrate to the tip of the villus at which they are shed. It is not understood how the intestinal barrier is maintained during this high cell turnover. The aim of this study was to use high-resolution in vivo light microscopy to investigate the mechanism of epithelial shedding and the site of the permeability barrier during cell shedding.
METHODS
A laparotomy was performed on anesthetized mice, and a segment of small intestine was opened. The exposed epithelial surface of the intestine was imaged by multiphoton microscopy. Nuclei, cytosol, and cell membranes were imaged using the dyes Hoescht 33258, BCECF, a transgenically expressed fluorescent protein, and the membrane dye DiI. The fluorescent caspase substrate PhiPhiLux was used to detect apoptosis.
RESULTS
In the epithelial monolayer, gaps were observed that lacked nuclei or cytosol but appeared to be filled with an impermeable substance. Studies with membrane impermeant fluorophores (Lucifer Yellow and Alexa-dextran) showed that the impermeable substance completely fills the void left by the absent cell. Only a fraction of gaps have either ZO-1 staining or cytoplasmic extensions from neighboring cells at the basal pole. Time-lapse studies reveal that cell shedding results in genesis of a gap and that shedding usually occurs prior to detectable cellular activation of caspase 3 or nuclear condensation.
CONCLUSIONS
Results suggest that epithelial barrier function is sustained at the apical pole of the epithelial layer, despite discontinuities in the cellular layer.
Publication
Journal: Journal of Experimental Psychology: Learning Memory and Cognition
August/21/2008
Abstract
The item-specific proportion congruent (ISPC) effect refers to the observation that the Stroop effect is larger for words that are presented mostly in congruent colors (e.g., BLUE presented 75% of the time in blue) and smaller for words that are presented mostly in a given incongruent color (e.g., YELLOW presented 75% of the time in orange). One account of the ISPC effect, the modulation hypothesis, is that participants modulate attention based on the identity of the word (i.e., participants allow the word to influence responding when it is presented mostly in its congruent color). Another account, the contingency hypothesis, is that participants use the word to predict the response that they will need to make (e.g., if the word is YELLOW, then the response is probably "orange"). Reanalyses of data from L. L. Jacoby, D. S. Lindsay, and S. Hessels (2003), along with results from new experiments, are inconsistent with the modulation hypothesis but entirely consistent with the contingency hypothesis. A response threshold mechanism that uses contingency information provides a sufficient account of the data.
Publication
Journal: Journal of chromatography
March/30/1977
Abstract
The chromogenic reagent described has been tested with seventy-nine indole derivatives and found to be very sensitive and indole-specific. The lower limit of detection on silica gel thin-layer plates was between 25 and 50 ng for most indoles. Phenols and hydroxy-, and amino-benzoic acids, hydroxy-, and methoxy-cinnamic acids did not yield chromophores with the exception of p-amino-benzoic acid and p-hydroxy-cinnamic acid which gave yellow and pink chromophores at concentrations greater than 1 and 2 mug. Although many of the C-3 substituted indoles such as indole-3-acetic acid and tryptamine had colors in the reddish-violet-blue color region, most exhibited sufficient color differentiation to allow their identification by thin-layer chromatography. The procedure was simple and required only 10 min from the time of spraying the thin-layer plate until full color development was reached. The colors had a wide spectral range from yellow of the indole-3-glyoxylamide chromophore to blue of the melatonin chromophore, and were extremely stable.
Authors
Publication
Journal: Insect Biochemistry and Molecular Biology
June/12/2008
Abstract
Male reproductive gland proteins (mRGPs) impact the physiology and/or behavior of mated females in a broad range of organisms. We sought to identify mRGPs of the yellow fever mosquito, Aedes aegypti, the primary vector of dengue and yellow fever viruses. Earlier studies with Ae. aegypti demonstrated that "matrone" (a partially purified male reproductive accessory gland substance) or male accessory gland fluid injected into virgin female Ae. aegypti affect female sexual refractoriness, blood feeding and digestion, flight, ovarian development, and oviposition. Using bioinformatic comparisons to Drosophila melanogaster accessory gland proteins and mass spectrometry of proteins from Ae. aegypti male accessory glands and ejaculatory ducts (AG/ED) and female reproductive tracts, we identified 63 new putative Ae. aegypti mRGPs. Twenty-one of these proteins were found in the reproductive tract of mated females but not of virgin females suggesting that they are transferred from males to females during mating. Most of the putative mRGPs fall into the same protein classes as mRGPs in other organisms, although some appear to be evolving rapidly and lack identifiable homologs in Culex pipiens, Anopheles gambiae, and D. melanogaster. Our results identify candidate male-derived molecules that may have an important influence on behavior, survival, and reproduction of female mosquitoes.
Publication
Journal: Neuroscience
August/3/2011
Abstract
Glucagon-like peptide 1 (GLP-1) and its analogue exendin-4 inhibit food intake, reduce blood glucose levels and increase blood pressure and heart rate by acting on GLP-1 receptors in many brain regions. Within the CNS, GLP-1 is produced only by preproglucagon (PPG) neurons. We suggest that PPG neurons mediate the central effects of GLP-1 by modulating sympathetic and vagal outflow. We therefore analysed the projections of PPG neurons to brain sites involved in autonomic control. In transgenic mice expressing yellow fluorescent protein (YFP) under the control of the PPG promoter, we assessed YFP-immunoreactive innervation using an anti-GFP antiserum and avidin-biotin-peroxidase. PPG neurons were intensely YFP-immunoreactive and axons could be easily discriminated from dendrites. YFP-immunoreactive cell bodies occurred primarily within the caudal nucleus tractus solitarius (NTS) with additional somata ventral to the hypoglossal nucleus, in raphé obscurus and in the intermediate reticular nucleus. The caudal NTS contained a dense network of dendrites, some of which extended into the area postrema. Immunoreactive axons were widespread throughout NTS, dorsal vagal nucleus and reticular nucleus with few in the hypoglossal nucleus and pyramids. The dorsomedial and paraventricular hypothalamic nuclei, ventrolateral periaqueductal grey and thalamic paraventricular nucleus exhibited heavy innervation. The area postrema, rostral ventrolateral medulla, pontine central grey, locus coeruleus/Barrington's nucleus, arcuate nucleus and the vascular organ of the lamina terminalis were moderately innervated. Only a few axons occurred in the amygdala and subfornical organ. Our results demonstrate that PPG neurons innervate primarily brain regions involved in autonomic control. Thus, central PPG neurons are ideally situated to modulate sympathetic and parasympathetic outflow through input at a variety of central sites. Our data also highlight that immunohistochemistry improves detection of neurons expressing YFP. Hence, animals in which specific populations of neurons have been genetically-modified to express fluorescent proteins are likely to prove ideal for anatomical studies.
Publication
Journal: Plant Journal
February/4/2009
Abstract
Yellowing, which is related to the degradation of chlorophyll and chlorophyll-protein complexes, is a notable phenomenon during leaf senescence. NON-YELLOW COLORING 1 (NYC1) in rice encodes a membrane-localized short-chain dehydrogenase/reductase (SDR) that is thought to represent a chlorophyll b reductase necessary for catalyzing the first step of chlorophyll b degradation. Analysis of the nyc1 mutant, which shows the stay-green phenotype, revealed that chlorophyll b degradation is required for the degradation of light-harvesting complex II and thylakoid grana in leaf senescence. Phylogenetic analysis further revealed the existence of NYC1-LIKE (NOL) as the most closely related protein to NYC1. In the present paper, the nol mutant in rice was also found to show a stay-green phenotype very similar to that of the nyc1 mutant, i.e. the degradation of chlorophyll b was severely inhibited and light-harvesting complex II was selectively retained during senescence, resulting in the retention of thylakoid grana even at a late stage of senescence. The nyc1 nol double mutant did not show prominent enhancement of inhibition of chlorophyll degradation. NOL was localized on the stromal side of the thylakoid membrane despite the lack of a transmembrane domain. Immunoprecipitation analysis revealed that NOL and NYC1 interact physically in vitro. These observations suggest that NOL and NYC1 are co-localized in the thylakoid membrane and act in the form of a complex as a chlorophyll b reductase in rice.
Publication
Journal: Journal of Pharmacology and Experimental Therapeutics
August/27/2003
Abstract
The sigma-1 receptors bind diverse kinds of psychoactive compounds, including cocaine, and translocate upon stimulation by these compounds. However, the exact intracellular localization and dynamics of sigma-1 receptors have been unclear. We recently found that sigma-1 receptors specifically localize on cholesterol-enriched loci on the endoplasmic reticulum (ER) membrane that function as neutral lipid storage sites (i.e., ER lipid droplets or ER-LDs) from which neutral lipids bud out to form cytosolic lipid droplets. By combining immunocytochemistry and real-time monitoring of enhanced yellow fluorescent protein (EYFP)-tagged sigma-1 receptors (Sig-1R-EYFP) in living cells, we characterized the sigma-1 receptor translocation in this study. (+)-Pentazocine, a selective sigma-1 receptor agonist, causes a significant decrease of sigma-1 receptors in ER-LDs and a diffused distribution of sigma-1 receptors over the entire endoplasmic reticulum reticular network in NG108-15 cells. In the presence of sigma-1 receptor agonists, Sig-1R-EYFP move out from ER-LDs and slide along the endoplasmic reticulum network toward nuclear envelope and the tip of neurites. Fluorescence recovery after photobleaching analysis demonstrates that Sig-1R-EYFP on endoplasmic reticulum reticular network are highly mobile compared with those in ER-LDs. A sucrose gradient fractionation study shows that (+)-pentazocine shifts sigma-1 receptors from ER-LD membranes to higher density membranes. These results indicate that sigma-1 receptors localize on ER-LDs and upon stimulation translocate on continuous endoplasmic reticulum reticular network toward peripheries of cells. Because sigma-1 receptors specifically target ER lipid storage sites and compartmentalize neutral lipids therein, these results suggest that sigma-1 receptors' dynamic translocation might affect lipid transport and distribution in neuronal cells.
Publication
Journal: Expert Review of Vaccines
June/5/2006
Abstract
Yellow fever, a mosquito-borne viral hemorrhagic fever, is one of the most lethal diseases of humankind. The etiologic agent is the prototype member of the genus Flavivirus, family Flaviviridae, a group of small, enveloped, positive-sense, single-strand RNA viruses. Approximately one in seven people who become infected develop a rapidly progressive illness, with hepatitis, renal failure, hemorrhage and cardiovascular shock, with a case fatality rate of 20-50%. Yellow fever occurs in sub-Saharan Africa and tropical South America, where it remains a continuing public health problem of varying magnitude, depending on the level of vaccination coverage in the human population and cyclical, ecologic and climatic factors that influence virus transmission.
Publication
Journal: Proceedings of the National Academy of Sciences of the United States of America
February/27/2013
Abstract
To better understand how innate immune responses to vaccination can lead to lasting protective immunity, we used a systems approach to define immune signatures in humans over 1 wk following MRKAd5/HIV vaccination that predicted subsequent HIV-specific T-cell responses. Within 24 h, striking increases in peripheral blood mononuclear cell gene expression associated with inflammation, IFN response, and myeloid cell trafficking occurred, and lymphocyte-specific transcripts decreased. These alterations were corroborated by marked serum inflammatory cytokine elevations and egress of circulating lymphocytes. Responses of vaccinees with preexisting adenovirus serotype 5 (Ad5) neutralizing antibodies were strongly attenuated, suggesting that enhanced HIV acquisition in Ad5-seropositive subgroups in the Step Study may relate to the lack of appropriate innate activation rather than to increased systemic immune activation. Importantly, patterns of chemoattractant cytokine responses at 24 h and alterations in 209 peripheral blood mononuclear cell transcripts at 72 h were predictive of subsequent induction and magnitude of HIV-specific CD8(+) T-cell responses. This systems approach provides a framework to compare innate responses induced by vectors, as shown here by contrasting the more rapid, robust response to MRKAd5/HIV with that to yellow fever vaccine. When applied iteratively, the findings may permit selection of HIV vaccine candidates eliciting innate immune response profiles more likely to drive HIV protective immunity.
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