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  1. Article ; Online: A novel molecular rotor facilitates detection of p53-DNA interactions using the Fluorescent Intercalator Displacement Assay

    Walter L. Goh / Min Yen Lee / Ting Xiang Lim / Joy S. Chua / Sydney Brenner / Farid J. Ghadessy / Yin Nah Teo

    Scientific Reports, Vol 8, Iss 1, Pp 1-

    2018  Volume 13

    Abstract: Abstract We have investigated the use of fluorescent molecular rotors as probes for detection of p53 binding to DNA. These are a class of fluorophores that undergo twisted intramolecular charge transfer (TICT). They are non-fluorescent in a freely ... ...

    Abstract Abstract We have investigated the use of fluorescent molecular rotors as probes for detection of p53 binding to DNA. These are a class of fluorophores that undergo twisted intramolecular charge transfer (TICT). They are non-fluorescent in a freely rotating conformation and experience a fluorescence increase when restricted in the planar conformation. We hypothesized that intercalation of a molecular rotor between DNA base pairs would result in a fluorescence turn-on signal. Upon displacement by a DNA binding protein, measurable loss of signal would facilitate use of the molecular rotor in the fluorescent intercalator displacement (FID) assay. A panel of probes was interrogated using the well-established p53 model system across various DNA response elements. A novel, readily synthesizable molecular rotor incorporating an acridine orange DNA intercalating group (AO-R) outperformed other conventional dyes in the FID assay. It enabled relative measurement of p53 sequence-specific DNA interactions and study of the dominant-negative effects of cancer-associated p53 mutants. In a further application, AO-R also proved useful for staining apoptotic cells in live zebrafish embryos.
    Keywords Medicine ; R ; Science ; Q
    Subject code 500
    Language English
    Publishing date 2018-08-01T00:00:00Z
    Publisher Nature Publishing Group
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Mouse transgenesis identifies conserved functional enhancers and cis-regulatory motif in the vertebrate LIM homeobox gene Lhx2 locus.

    Alison P Lee / Sydney Brenner / Byrappa Venkatesh

    PLoS ONE, Vol 6, Iss 5, p e

    2011  Volume 20088

    Abstract: The vertebrate Lhx2 is a member of the LIM homeobox family of transcription factors. It is essential for the normal development of the forebrain, eye, olfactory system and liver as well for the differentiation of lymphoid cells. However, despite the ... ...

    Abstract The vertebrate Lhx2 is a member of the LIM homeobox family of transcription factors. It is essential for the normal development of the forebrain, eye, olfactory system and liver as well for the differentiation of lymphoid cells. However, despite the highly restricted spatio-temporal expression pattern of Lhx2, nothing is known about its transcriptional regulation. In mammals and chicken, Crb2, Dennd1a and Lhx2 constitute a conserved linkage block, while the intervening Dennd1a is lost in the fugu Lhx2 locus. To identify functional enhancers of Lhx2, we predicted conserved noncoding elements (CNEs) in the human, mouse and fugu Crb2-Lhx2 loci and assayed their function in transgenic mouse at E11.5. Four of the eight CNE constructs tested functioned as tissue-specific enhancers in specific regions of the central nervous system and the dorsal root ganglia (DRG), recapitulating partial and overlapping expression patterns of Lhx2 and Crb2 genes. There was considerable overlap in the expression domains of the CNEs, which suggests that the CNEs are either redundant enhancers or regulating different genes in the locus. Using a large set of CNEs (810 CNEs) associated with transcription factor-encoding genes that express predominantly in the central nervous system, we predicted four over-represented 8-mer motifs that are likely to be associated with expression in the central nervous system. Mutation of one of them in a CNE that drove reporter expression in the neural tube and DRG abolished expression in both domains indicating that this motif is essential for expression in these domains. The failure of the four functional enhancers to recapitulate the complete expression pattern of Lhx2 at E11.5 indicates that there must be other Lhx2 enhancers that are either located outside the region investigated or divergent in mammals and fishes. Other approaches such as sequence comparison between multiple mammals are required to identify and characterize such enhancers.
    Keywords Medicine ; R ; Science ; Q
    Subject code 570
    Language English
    Publishing date 2011-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Characterization of the Runx gene family in a jawless vertebrate, the Japanese lamprey (Lethenteron japonicum).

    Giselle Sek Suan Nah / Boon-Hui Tay / Sydney Brenner / Motomi Osato / Byrappa Venkatesh

    PLoS ONE, Vol 9, Iss 11, p e

    2014  Volume 113445

    Abstract: The cyclostomes (jawless vertebrates), comprising lampreys and hagfishes, are the sister group of jawed vertebrates (gnathostomes) and are hence an important group for the study of vertebrate evolution. In mammals, three Runx genes, Runx1, Runx2 and ... ...

    Abstract The cyclostomes (jawless vertebrates), comprising lampreys and hagfishes, are the sister group of jawed vertebrates (gnathostomes) and are hence an important group for the study of vertebrate evolution. In mammals, three Runx genes, Runx1, Runx2 and Runx3, encode transcription factors that are essential for cell proliferation and differentiation in major developmental pathways such as haematopoiesis, skeletogenesis and neurogenesis and are frequently associated with diseases. We describe here the characterization of Runx gene family members from a cyclostome, the Japanese lamprey (Lethenteron japonicum). The Japanese lamprey contains three Runx genes, RunxA, RunxB, and RunxC. However, phylogenetic and synteny analyses suggest that they are not one-to-one orthologs of gnathostome Runx1, Runx2 and Runx3. The major protein domains and motifs found in gnathostome Runx proteins are highly conserved in the lamprey Runx proteins. Although all gnathostome Runx genes each contain two alternative promoters, P1 (distal) and P2 (proximal), only lamprey RunxB possesses the alternative promoters; lamprey RunxA and RunxC contain only P2 and P1 promoter, respectively. Furthermore, the three lamprey Runx genes give rise to fewer alternative isoforms than the three gnathostome Runx genes. The promoters of the lamprey Runx genes lack the tandem Runx-binding motifs that are highly conserved among the P1 promoters of gnathostome Runx1, Runx2 and Runx3 genes; instead these promoters contain dispersed single Runx-binding motifs. The 3'UTR of lamprey RunxB contains binding sites for miR-27 and miR-130b/301ab, which are conserved in mammalian Runx1 and Runx3, respectively. Overall, the Runx genes in lamprey seem to have experienced a different evolutionary trajectory from that of gnathostome Runx genes which are highly conserved all the way from cartilaginous fishes to mammals.
    Keywords Medicine ; R ; Science ; Q
    Subject code 572
    Language English
    Publishing date 2014-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Sequencing and analysis of full-length cDNAs, 5'-ESTs and 3'-ESTs from a cartilaginous fish, the elephant shark (Callorhinchus milii).

    Yue Ying Tan / Rimantas Kodzius / Boon-Hui Tay / Alice Tay / Sydney Brenner / Byrappa Venkatesh

    PLoS ONE, Vol 7, Iss 10, p e

    2012  Volume 47174

    Abstract: Cartilaginous fishes are the most ancient group of living jawed vertebrates (gnathostomes) and are, therefore, an important reference group for understanding the evolution of vertebrates. The elephant shark (Callorhinchus milii), a holocephalan ... ...

    Abstract Cartilaginous fishes are the most ancient group of living jawed vertebrates (gnathostomes) and are, therefore, an important reference group for understanding the evolution of vertebrates. The elephant shark (Callorhinchus milii), a holocephalan cartilaginous fish, has been identified as a model cartilaginous fish genome because of its compact genome (∼910 Mb) and a genome project has been initiated to obtain its whole genome sequence. In this study, we have generated and sequenced full-length enriched cDNA libraries of the elephant shark using the 'oligo-capping' method and Sanger sequencing. A total of 6,778 full-length protein-coding cDNA and 10,701 full-length noncoding cDNA were sequenced from six tissues (gills, intestine, kidney, liver, spleen, and testis) of the elephant shark. Analysis of their polyadenylation signals showed that polyadenylation usage in elephant shark is similar to that in mammals. Furthermore, both coding and noncoding transcripts of the elephant shark use the same proportion of canonical polyadenylation sites. Besides BLASTX searches, protein-coding transcripts were annotated by Gene Ontology, InterPro domain, and KEGG pathway analyses. By comparing elephant shark genes to bony vertebrate genes, we identified several ancient genes present in elephant shark but differentially lost in tetrapods or teleosts. Only ∼6% of elephant shark noncoding cDNA showed similarity to known noncoding RNAs (ncRNAs). The rest are either highly divergent ncRNAs or novel ncRNAs. In addition to full-length transcripts, 30,375 5'-ESTs and 41,317 3'-ESTs were sequenced and annotated. The clones and transcripts generated in this study are valuable resources for annotating transcription start sites, exon-intron boundaries, and UTRs of genes in the elephant shark genome, and for the functional characterization of protein sequences. These resources will also be useful for annotating genes in other cartilaginous fishes whose genomes have been targeted for whole genome sequencing.
    Keywords Medicine ; R ; Science ; Q
    Subject code 572
    Language English
    Publishing date 2012-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article ; Online: Aptamer selection by high-throughput sequencing and informatic analysis

    Shawn Hoon / Bin Zhou / Kim D. Janda / Sydney Brenner / Jonathan Scolnick

    BioTechniques, Vol 51, Iss 6, Pp 413-

    2011  Volume 416

    Abstract: Traditional methods for selecting aptamers require multiple rounds of selection and optimization in order to identify aptamers that bind with high affinity to their targets. Here we describe an assay that requires only one round of positive selection ... ...

    Abstract Traditional methods for selecting aptamers require multiple rounds of selection and optimization in order to identify aptamers that bind with high affinity to their targets. Here we describe an assay that requires only one round of positive selection followed by high-throughput DNA sequencing and informatic analysis in order to select high-affinity aptamers. The assay is flexible, requires less hands on time, and can be used by laboratories with minimal expertise in aptamer biology to quickly select high-affinity aptamers to a target of interest. This assay has been utilized to successfully identify aptamers that bind to thrombin with dissociation constants in the nanomolar range.
    Keywords aptamer ; high throughput sequencing ; informatics ; Biology (General) ; QH301-705.5
    Language English
    Publishing date 2011-12-01T00:00:00Z
    Publisher Future Science Ltd
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article: A survey of ancient conserved non-coding elements in the PAX6 locus reveals a landscape of interdigitated cis-regulatory archipelagos

    Bhatia, Shipra / Byrappa Venkatesh / Dirk A. Kleinjan / Emma Murdoch / Jack Monahan / Philippe Gautier / Sydney Brenner / Veronica van Heyningen / Vydianathan Ravi

    Developmental biology. 2014 Mar. 15, v. 387, no. 2

    2014  

    Abstract: Biological differences between cell types and developmental processes are characterised by differences in gene expression profiles. Gene-distal enhancers are key components of the regulatory networks that specify the tissue-specific expression patterns ... ...

    Abstract Biological differences between cell types and developmental processes are characterised by differences in gene expression profiles. Gene-distal enhancers are key components of the regulatory networks that specify the tissue-specific expression patterns driving embryonic development and cell fate decisions, and variations in their sequences are a major contributor to genetic disease and disease susceptibility. Despite advances in the methods for discovery of putative cis-regulatory sequences, characterisation of their spatio-temporal enhancer activities in a mammalian model system remains a major bottle-neck. We employed a strategy that combines gnathostome sequence conservation with transgenic mouse and zebrafish reporter assays to survey the genomic locus of the developmental control gene PAX6 for the presence of novel cis-regulatory elements. Sequence comparison between human and the cartilaginous elephant shark (Callorhinchus milii) revealed several ancient gnathostome conserved non-coding elements (agCNEs) dispersed widely throughout the PAX6 locus, extending the range of the known PAX6 cis-regulatory landscape to contain the full upstream PAX6-RCN1 intergenic region. Our data indicates that ancient conserved regulatory sequences can be tested effectively in transgenic zebrafish even when not conserved in zebrafish themselves. The strategy also allows efficient dissection of compound regulatory regions previously assessed in transgenic mice. Remarkable overlap in expression patterns driven by sets of agCNEs indicates that PAX6 resides in a landscape of multiple tissue-specific regulatory archipelagos.
    Keywords Danio rerio ; disease resistance ; embryogenesis ; genes ; genetic disorders ; genomics ; humans ; intergenic DNA ; loci ; mice ; models ; regulatory sequences ; sequence analysis ; sharks ; surveys ; transgenic animals
    Language English
    Dates of publication 2014-0315
    Size p. 214-228.
    Publishing place Elsevier Inc.
    Document type Article
    ZDB-ID 1114-9
    ISSN 1095-564X ; 0012-1606
    ISSN (online) 1095-564X
    ISSN 0012-1606
    DOI 10.1016/j.ydbio.2014.01.007
    Database NAL-Catalogue (AGRICOLA)

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  7. Article ; Online: Evolution and functional characterisation of melanopsins in a deep-sea chimaera (elephant shark, Callorhinchus milii).

    Wayne I L Davies / Boon-Hui Tay / Lei Zheng / Janine A Danks / Sydney Brenner / Russell G Foster / Shaun P Collin / Mark W Hankins / Byrappa Venkatesh / David M Hunt

    PLoS ONE, Vol 7, Iss 12, p e

    2012  Volume 51276

    Abstract: Non-visual photoreception in mammals is primarily mediated by two splice variants that derive from a single melanopsin (OPN4M) gene, whose expression is restricted to a subset of retinal ganglion cells. Physiologically, this sensory system regulates the ... ...

    Abstract Non-visual photoreception in mammals is primarily mediated by two splice variants that derive from a single melanopsin (OPN4M) gene, whose expression is restricted to a subset of retinal ganglion cells. Physiologically, this sensory system regulates the photoentrainment of many biological rhythms, such as sleep via the melatonin endocrine system and pupil constriction. By contrast, melanopsin exists as two distinct lineages in non-mammals, opn4m and opn4x, and is broadly expressed in a wide range of tissue types, including the eye, brain, pineal gland and skin. Despite these findings, the evolution and function of melanopsin in early vertebrates are largely unknown. We, therefore, investigated the complement of opn4 classes present in the genome of a model deep-sea cartilaginous species, the elephant shark (Callorhinchus milii), as a representative vertebrate that resides at the base of the gnathostome (jawed vertebrate) lineage. We reveal that three melanopsin genes, opn4m1, opn4m2 and opn4x, are expressed in multiple tissues of the elephant shark. The two opn4m genes are likely to have arisen as a result of a lineage-specific duplication, whereas "long" and "short" splice variants are generated from a single opn4x gene. By using a heterologous expression system, we suggest that these genes encode functional photopigments that exhibit both "invertebrate-like" bistable and classical "vertebrate-like" monostable biochemical characteristics. We discuss the evolution and function of these melanopsin pigments within the context of the diverse photic and ecological environments inhabited by this chimaerid holocephalan, as well as the origin of non-visual sensory systems in early vertebrates.
    Keywords Medicine ; R ; Science ; Q
    Subject code 612
    Language English
    Publishing date 2012-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: Integrative Genome-wide Analysis Reveals Cooperative Regulation of Alternative Splicing by hnRNP Proteins

    Stephanie C. Huelga / Anthony Q. Vu / Justin D. Arnold / Tiffany Y. Liang / Patrick P. Liu / Bernice Y. Yan / John Paul Donohue / Lily Shiue / Shawn Hoon / Sydney Brenner / Manuel Ares, Jr. / Gene W. Yeo

    Cell Reports, Vol 1, Iss 2, Pp 167-

    2012  Volume 178

    Abstract: Understanding how RNA binding proteins control the splicing code is fundamental to human biology and disease. Here, we present a comprehensive study to elucidate how heterogeneous nuclear ribonucleoparticle (hnRNP) proteins, among the most abundant RNA ... ...

    Abstract Understanding how RNA binding proteins control the splicing code is fundamental to human biology and disease. Here, we present a comprehensive study to elucidate how heterogeneous nuclear ribonucleoparticle (hnRNP) proteins, among the most abundant RNA binding proteins, coordinate to regulate alternative pre-mRNA splicing (AS) in human cells. Using splicing-sensitive microarrays, crosslinking and immunoprecipitation coupled with high-throughput sequencing (CLIP-seq), and cDNA sequencing, we find that more than half of all AS events are regulated by multiple hnRNP proteins and that some combinations of hnRNP proteins exhibit significant synergy, whereas others act antagonistically. Our analyses reveal position-dependent RNA splicing maps, in vivo consensus binding sites, a surprising level of cross- and autoregulation among hnRNP proteins, and the coordinated regulation by hnRNP proteins of dozens of other RNA binding proteins and genes associated with cancer. Our findings define an unprecedented degree of complexity and compensatory relationships among hnRNP proteins and their splicing targets that likely confer robustness to cells.
    Keywords Biology (General) ; QH301-705.5
    Subject code 570
    Language English
    Publishing date 2012-02-01T00:00:00Z
    Publisher Elsevier
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  9. Article ; Online: Survey sequencing and comparative analysis of the elephant shark (Callorhinchus milii) genome.

    Byrappa Venkatesh / Ewen F Kirkness / Yong-Hwee Loh / Aaron L Halpern / Alison P Lee / Justin Johnson / Nidhi Dandona / Lakshmi D Viswanathan / Alice Tay / J Craig Venter / Robert L Strausberg / Sydney Brenner

    PLoS Biology, Vol 5, Iss 4, p e

    2007  Volume 101

    Abstract: Owing to their phylogenetic position, cartilaginous fishes (sharks, rays, skates, and chimaeras) provide a critical reference for our understanding of vertebrate genome evolution. The relatively small genome of the elephant shark, Callorhinchus milii, a ... ...

    Abstract Owing to their phylogenetic position, cartilaginous fishes (sharks, rays, skates, and chimaeras) provide a critical reference for our understanding of vertebrate genome evolution. The relatively small genome of the elephant shark, Callorhinchus milii, a chimaera, makes it an attractive model cartilaginous fish genome for whole-genome sequencing and comparative analysis. Here, the authors describe survey sequencing (1.4x coverage) and comparative analysis of the elephant shark genome, one of the first cartilaginous fish genomes to be sequenced to this depth. Repetitive sequences, represented mainly by a novel family of short interspersed element-like and long interspersed element-like sequences, account for about 28% of the elephant shark genome. Fragments of approximately 15,000 elephant shark genes reveal specific examples of genes that have been lost differentially during the evolution of tetrapod and teleost fish lineages. Interestingly, the degree of conserved synteny and conserved sequences between the human and elephant shark genomes are higher than that between human and teleost fish genomes. Elephant shark contains putative four Hox clusters indicating that, unlike teleost fish genomes, the elephant shark genome has not experienced an additional whole-genome duplication. These findings underscore the importance of the elephant shark as a critical reference vertebrate genome for comparative analysis of the human and other vertebrate genomes. This study also demonstrates that a survey-sequencing approach can be applied productively for comparative analysis of distantly related vertebrate genomes.
    Keywords Biology (General) ; QH301-705.5
    Subject code 572
    Language English
    Publishing date 2007-04-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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