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Sundaresan V, Springer P, Volpe T, Haward S, Jones JD, Dean C, Ma H, Martienssen R. Patterns of gene action in plant development revealed by enhancer trap and gene trap transposable elements. Genes Dev 1995; 9:1797-810. [PMID: 7622040 DOI: 10.1101/gad.9.14.1797] [Citation(s) in RCA: 445] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 01/26/2023]
Abstract
The crucifer Arabidopsis thaliana has been used widely as a model organism for the study of plant development. We describe here the development of an efficient insertional mutagenesis system in Arabidopsis that permits identification of genes by their patterns of expression during development. Transposable elements of the Ac/Ds system carrying the GUS reporter gene have been designed to act as enhancer traps or gene traps. A novel selection scheme maximizes recovery of unlinked transposition events. In this study 491 plants carrying independent transposon insertions were generated and screened for expression patterns. One-half of the enhancer trap insertions and one-quarter of the gene trap insertions displayed GUS expression in seedlings or flowers, including expression patterns specific to organs, tissues, cell types, or developmental stages. The patterns identify genes that act during organogenesis, pattern formation, or cell differentiation. Transposon insertion lines with specific GUS expression patterns provide valuable markers for studies of Arabidopsis development and identify new cell types or subtypes in plants. The diversity of gene expression patterns generated suggests that the identification and cloning of Arabidopsis genes expressed in any developmental process is feasible using this system.
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30 |
445 |
2
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Yang WC, Ye D, Xu J, Sundaresan V. The SPOROCYTELESS gene of Arabidopsis is required for initiation of sporogenesis and encodes a novel nuclear protein. Genes Dev 1999; 13:2108-17. [PMID: 10465788 PMCID: PMC316961 DOI: 10.1101/gad.13.16.2108] [Citation(s) in RCA: 392] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/25/2022]
Abstract
The formation of haploid spores marks the initiation of the gametophytic phase of the life cycle of all vascular plants ranging from ferns to angiosperms. In angiosperms, this process is initiated by the differentiation of a subset of floral cells into sporocytes, which then undergo meiotic divisions to form microspores and megaspores. Currently, there is little information available regarding the genes and proteins that regulate this key step in plant reproduction. We report here the identification of a mutation, SPOROCYTELESS (SPL), which blocks sporocyte formation in Arabidopsis thaliana. Analysis of the SPL mutation suggests that development of the anther walls and the tapetum and microsporocyte formation are tightly coupled, and that nucellar development may be dependent on megasporocyte formation. Molecular cloning of the SPL gene showed that it encodes a novel nuclear protein related to MADS box transcription factors and that it is expressed during microsporogenesis and megasporogenesis. These data suggest that the SPL gene product is a transcriptional regulator of sporocyte development in Arabidopsis.
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research-article |
26 |
392 |
3
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Springer PS, McCombie WR, Sundaresan V, Martienssen RA. Gene trap tagging of PROLIFERA, an essential MCM2-3-5-like gene in Arabidopsis. Science 1995; 268:877-80. [PMID: 7754372 DOI: 10.1126/science.7754372] [Citation(s) in RCA: 218] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 01/27/2023]
Abstract
Gene trap transposon mutagenesis can identify essential genes whose functions in later development are obscured by an early lethal phenotype. In higher plants, many genes are required for haploid gametophyte viability, so that the phenotypic effects of their disruption cannot be readily observed in the diploid plant body. The PROLIFERA (PRL) gene, identified by gene trap transposon mutagenesis in Arabidopsis, is required for megaga-metophyte and embryo development. Reporter gene expression patterns revealed that PRL was expressed in dividing cells throughout the plant. PRL is related to the MCM2-3-5 family of yeast genes that are required for the initiation of DNA replication.
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30 |
218 |
4
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Andrews W, Liapi A, Plachez C, Camurri L, Zhang J, Mori S, Murakami F, Parnavelas JG, Sundaresan V, Richards LJ. Robo1 regulates the development of major axon tracts and interneuron migration in the forebrain. Development 2006; 133:2243-52. [PMID: 16690755 DOI: 10.1242/dev.02379] [Citation(s) in RCA: 196] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/20/2022]
Abstract
The Slit genes encode secreted ligands that regulate axon branching, commissural axon pathfinding and neuronal migration. The principal identified receptor for Slit is Robo (Roundabout in Drosophila). To investigate Slit signalling in forebrain development, we generated Robo1 knockout mice by targeted deletion of exon 5 of the Robo1 gene. Homozygote knockout mice died at birth, but prenatally displayed major defects in axon pathfinding and cortical interneuron migration. Axon pathfinding defects included dysgenesis of the corpus callosum and hippocampal commissure, and abnormalities in corticothalamic and thalamocortical targeting. Slit2 and Slit1/2 double mutants display malformations in callosal development, and in corticothalamic and thalamocortical targeting, as well as optic tract defects. In these animals, corticothalamic axons form large fasciculated bundles that aberrantly cross the midline at the level of the hippocampal and anterior commissures, and more caudally at the medial preoptic area. Such phenotypes of corticothalamic targeting were not observed in Robo1 knockout mice but, instead, both corticothalamic and thalamocortical axons aberrantly arrived at their respective targets at least 1 day earlier than controls. By contrast, in Slit mutants, fewer thalamic axons actually arrive in the cortex during development. Finally, significantly more interneurons (up to twice as many at E12.5 and E15.5) migrated into the cortex of Robo1 knockout mice, particularly in both rostral and parietal regions, but not caudal cortex. These results indicate that Robo1 mutants have distinct phenotypes, some of which are different from those described in Slit mutants, suggesting that additional ligands, receptors or receptor partners are likely to be involved in Slit/Robo signalling.
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Research Support, N.I.H., Extramural |
19 |
196 |
5
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Colasanti J, Yuan Z, Sundaresan V. The indeterminate gene encodes a zinc finger protein and regulates a leaf-generated signal required for the transition to flowering in maize. Cell 1998; 93:593-603. [PMID: 9604934 DOI: 10.1016/s0092-8674(00)81188-5] [Citation(s) in RCA: 188] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 02/07/2023]
Abstract
Flowering in plants is a consequence of the transition of the shoot apex from vegetative to reproductive growth in response to environmental and internal signals. The indeterminate1 gene (id1) controls the transition to flowering in maize. We show by cloning the id1 gene that it encodes a protein with zinc finger motifs, suggesting that the id1 gene product functions as a transcriptional regulator of the floral transition. id1 mRNA expression studies and analyses of transposon-induced chimeric plants indicate that id1 acts non-cell-autonomously to regulate the production of a transmissible signal in the leaf that elicits the transformation of the shoot apex to reproductive development. These results provide molecular and genetic data consistent with the florigen hypothesis derived from classical plant physiology studies.
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27 |
188 |
6
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Ruvkun GB, Sundaresan V, Ausubel FM. Directed transposon Tn5 mutagenesis and complementation analysis of Rhizobium meliloti symbiotic nitrogen fixation genes. Cell 1982; 29:551-9. [PMID: 6288262 DOI: 10.1016/0092-8674(82)90171-4] [Citation(s) in RCA: 188] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 01/19/2023]
Abstract
An 18 kb region adjacent to and surrounding the genes for nitrogenase (nif) was cloned from the genome of the symbiotic nitrogen-fixing species Rhizobium meliloti. A total of 31 Tn5 insertions in the nif region were constructed and assayed for their effect on symbiotic nitrogen fixation (Fix phenotype). Fix- insertions were found in two clusters, one 6.3 kb region not containing essential symbiotic genes. The locations of at least three transcription units containing Fix genes were deduced from complementation analysis between genomic nif::Tn5 insertions and nif::Tn5 insertions on mobilizable cloning vectors. The locations of R. meliloti genes nifH, nifD and nifK, which code for the single subunit of the nitrogenase Fe protein and for the two subunits of the nitrogenase MoFe protein respectively, were determined by DNA hybridization to cloned Klebsiella pneumoniae nif genes and by comparison of partial R. meliloti DNA sequences with K. pneumoniae nif gene sequences. R. meliloti nifH, D and K are located in the 6.3 kb fix-::Tn5 cluster and are transcribed in the order nifH, nifD, nifK, which is the same order as in K. pneumoniae.
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Abstract
BACKGROUND Several processes of plant development, such as abscission, pollen release, fruit dehiscence, and seed dispersal, require organs or tissues to physically disassociate or split open. Due to the immobility of plant cells, these processes occur through coordinated mechanisms of cell separation that are not found in animals. Arabidopsis produces dry dehiscent fruits (siliques) making it a convenient system for the genetic study of cell separation associated with dehiscence. RESULTS We describe here a novel mutation in Arabidopsis called alcatraz (alc), which prevents dehiscence of fruit by specifically blocking the separation of the valve cells from the replum. The ALC gene is shown to encode a protein related to the myc/bHLH family of transcription factors and is expressed in the valve margins of the silique, which is the site of cell separation during dehiscence. Detailed studies using TEM indicates that ALC enables cell separation in Arabidopsis fruit dehiscence by promoting the differentiation of a strip of labile nonlignified cells sandwiched between layers of lignified cells. Transgenic plants expressing antisense or dominant-negative ALC are defective in silique dehiscence. CONCLUSIONS Cell separation in fruit dehiscence requires a specialized cell layer which is nonlignified and capable of autolysis, specified by a myc/bHLH protein encoded by ALC. These findings may have relevance to other processes requiring cell separation, as well as for the practical design of crops with reduced seed losses.
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177 |
8
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Parinov S, Sundaresan V. Functional genomics in Arabidopsis: large-scale insertional mutagenesis complements the genome sequencing project. Curr Opin Biotechnol 2000; 11:157-61. [PMID: 10753770 DOI: 10.1016/s0958-1669(00)00075-6] [Citation(s) in RCA: 165] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/25/2022]
Abstract
The ultimate goal of genome research on the model flowering plant Arabidopsis thaliana is the identification of all of the genes and understanding their functions. A major step towards this goal, the genome sequencing project, is nearing completion; however, functional studies of newly discovered genes have not yet kept up to this pace. Recent progress in large-scale insertional mutagenesis opens new possibilities for functional genomics in Arabidopsis. The number of T-DNA and transposon insertion lines from different laboratories will soon represent insertions into most Arabidopsis genes. Vast resources of gene knockouts are becoming available that can be subjected to different types of reverse genetics screens to deduce the functions of the sequenced genes.
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Review |
25 |
165 |
9
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Lu W, van Eerde AM, Fan X, Quintero-Rivera F, Kulkarni S, Ferguson H, Kim HG, Fan Y, Xi Q, Li QG, Sanlaville D, Andrews W, Sundaresan V, Bi W, Yan J, Giltay JC, Wijmenga C, de Jong TPVM, Feather SA, Woolf AS, Rao Y, Lupski JR, Eccles MR, Quade BJ, Gusella JF, Morton CC, Maas RL. Disruption of ROBO2 is associated with urinary tract anomalies and confers risk of vesicoureteral reflux. Am J Hum Genet 2007; 80:616-32. [PMID: 17357069 PMCID: PMC1852714 DOI: 10.1086/512735] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Received: 11/09/2006] [Accepted: 01/15/2007] [Indexed: 11/03/2022] Open
Abstract
Congenital anomalies of the kidney and urinary tract (CAKUT) include vesicoureteral reflux (VUR). VUR is a complex, genetically heterogeneous developmental disorder characterized by the retrograde flow of urine from the bladder into the ureter and is associated with reflux nephropathy, the cause of 15% of end-stage renal disease in children and young adults. We investigated a man with a de novo translocation, 46,X,t(Y;3)(p11;p12)dn, who exhibits multiple congenital abnormalities, including severe bilateral VUR with ureterovesical junction defects. This translocation disrupts ROBO2, which encodes a transmembrane receptor for SLIT ligand, and produces dominant-negative ROBO2 proteins that abrogate SLIT-ROBO signaling in vitro. In addition, we identified two novel ROBO2 intracellular missense variants that segregate with CAKUT and VUR in two unrelated families. Adult heterozygous and mosaic mutant mice with reduced Robo2 gene dosage also exhibit striking CAKUT-VUR phenotypes. Collectively, these results implicate the SLIT-ROBO signaling pathway in the pathogenesis of a subset of human VUR.
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MESH Headings
- Amino Acid Sequence
- Animals
- Blotting, Southern
- Blotting, Western
- Cell Line
- Chromosomes, Human, Pair 3/genetics
- Chromosomes, Human, Y/genetics
- DNA Mutational Analysis
- DNA Primers
- Genetic Predisposition to Disease
- Humans
- In Situ Hybridization, Fluorescence
- Male
- Mice
- Molecular Sequence Data
- Mutation, Missense/genetics
- Nerve Tissue Proteins/metabolism
- Pedigree
- Receptors, Immunologic/genetics
- Receptors, Immunologic/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Signal Transduction/genetics
- Translocation, Genetic/genetics
- Urinary Tract/abnormalities
- Vesico-Ureteral Reflux/genetics
- Vesico-Ureteral Reflux/pathology
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Comparative Study |
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156 |
10
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Colasanti J, Tyers M, Sundaresan V. Isolation and characterization of cDNA clones encoding a functional p34cdc2 homologue from Zea mays. Proc Natl Acad Sci U S A 1991; 88:3377-81. [PMID: 2014258 PMCID: PMC51450 DOI: 10.1073/pnas.88.8.3377] [Citation(s) in RCA: 154] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 12/29/2022] Open
Abstract
We describe the isolation of cDNA clones encoding a p34cdc2 homologue from a higher plant, Zea mays (maize). A full-length cDNA clone, cdc2ZmA, was isolated, sequenced, and shown to complement a cdc28 mutation in Saccharomyces cerevisiae. Comparison of the deduced amino acid sequence of the maize p34cdc2 protein with other homologues showed that it was 64% identical to human p34cdc2 and 63% identical to Schizosaccharomyces pombe and S. cerevisiae p34cdc2 proteins. Studies of expression of the maize cdc2 gene(s) by Northern blot analysis indicated a correlation between the abundance of cdc2 mRNA and the proliferative state of the tissue. Southern blot analysis, as well as isolation of another cDNA clone, cdc2ZmB, which is 96% identical to cdc2ZmA, indicates that maize has multiple cdc2 genes.
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research-article |
34 |
154 |
11
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Tantikanjana T, Yong JW, Letham DS, Griffith M, Hussain M, Ljung K, Sandberg G, Sundaresan V. Control of axillary bud initiation and shoot architecture in Arabidopsis through the SUPERSHOOT gene. Genes Dev 2001; 15:1577-88. [PMID: 11410537 PMCID: PMC312715 DOI: 10.1101/gad.887301] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 12/19/2022]
Abstract
The aerial architecture of flowering plants is determined to a large extent by shoot growth and shoot branching arising from the initiation and growth of axillary meristems. We have identified an Arabidopsis mutant, supershoot (sps), which is characterized by a massive overproliferation of shoots, such that a single plant can generate 500 or more inflorescences. Analysis of the mutant plants shows that the primary defect is because of an increase in the number of meristems formed in leaf axils, together with release of bud arrest, resulting in reiterative branch formation from rosette and cauline leaves. The SPS gene is shown here to encode a cytochrome P450, and together with a 3- to 9-fold increase in levels of Z-type cytokinins in sps mutant plants, indicate a role for SPS in modulating hormone levels. The expression pattern of SPS, with strong expression at the leaf axils, correlates well with the phenotypic defects. Our results indicate that control of shoot branching in Arabidopsis may be accomplished in part by suppression of axillary meristem initiation and growth through the localized attenuation of cytokinin levels at sites of bud initiation.
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research-article |
24 |
144 |
12
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Abstract
We have characterized a Rhizobium meliloti regulatory gene required for the expression of two closely linked symbiotic operons, the nitrogenase operon (nifHDK genes) and the "P2" operon. This regulatory gene maps to a 1.8 kb region located 5.5 kb upstream of the nifHDK operon. The regulatory gene is required for the accumulation of nifHDK and P2 mRNA and for the derepression of an R. meliloti nifH-lacZ fusion plasmid during symbiotic growth. The nifH and P2 promoters can be activated in free-living cultures of R. meliloti containing plasmids that produce the Escherichia coli ntrC(glnG) or the Klebsiella pneumoniae nifA regulatory gene products constitutively. The R. meliloti regulatory gene hybridizes to E. coli ntrC(glnG) and, to a lesser extent, to K. pneumoniae nifA DNA. Our results suggest that the R. meliloti regulatory gene acts as a positive transcriptional activator and that it is related to the K. pneumoniae nif regulatory genes.
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137 |
13
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Parinov S, Sevugan M, Ye D, Yang WC, Kumaran M, Sundaresan V. Analysis of flanking sequences from dissociation insertion lines: a database for reverse genetics in Arabidopsis. THE PLANT CELL 1999; 11:2263-70. [PMID: 10590156 PMCID: PMC144131 DOI: 10.1105/tpc.11.12.2263] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Academic Contribution Register] [Indexed: 04/14/2023]
Abstract
We have generated Dissociation (Ds) element insertions throughout the Arabidopsis genome as a means of random mutagenesis. Here, we present the molecular analysis of genomic sequences that flank the Ds insertions of 931 independent transposant lines. Flanking sequences from 511 lines proved to be identical or homologous to DNA or protein sequences in public databases, and disruptions within known or putative genes were indicated for 354 lines. Because a significant portion (45%) of the insertions occurred within sequences defined by GenBank BAC and P1 clones, we were able to assess the distribution of Ds insertions throughout the genome. We discovered a significant preference for Ds transposition to the regions adjacent to nucleolus organizer regions on chromosomes 2 and 4. Otherwise, the mapped insertions appeared to be evenly dispersed throughout the genome. For any given gene, insertions preferentially occurred at the 5' end, although disruption was clearly possible at any intragenic position. The insertion sites of >500 lines that could be characterized by reference to public databases are presented in a tabular format at http://www.plantcell. org/cgi/content/full/11/12/2263/DC1. This database should be of value to researchers using reverse genetics approaches to determine gene function.
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research-article |
26 |
116 |
14
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Andrews W, Barber M, Hernadez-Miranda LR, Xian J, Rakic S, Sundaresan V, Rabbitts TH, Pannell R, Rabbitts P, Thompson H, Erskine L, Murakami F, Parnavelas JG. The role of Slit-Robo signaling in the generation, migration and morphological differentiation of cortical interneurons. Dev Biol 2008; 313:648-58. [PMID: 18054781 DOI: 10.1016/j.ydbio.2007.10.052] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Received: 07/03/2007] [Revised: 10/12/2007] [Accepted: 10/31/2007] [Indexed: 10/22/2022]
Abstract
Cortical interneurons in rodents are generated in the ventral telencephalon and migrate tangentially into the cortex. This process requires the coordinated action of many intrinsic and extrinsic factors. Here we show that Robo1 and Robo2 receptor proteins are dynamically expressed throughout the period of corticogenesis and colocalize with interneuronal markers, suggesting that they play a role in the migration of these cells. Analysis of Robo mutants showed a marked increase in the number of interneurons in the cortices of Robo1(-/-), but not Robo2(-/-), animals throughout the period of corticogenesis and in adulthood; this excess number of interneurons was observed in all layers of the developing cortex. Using BrdU incorporation in dissociated cell cultures and phosphohistone-3 labeling in vivo, we demonstrated that the increased number of interneurons in Robo1(-/-) mice is, at least in part, due to increased proliferation. Interestingly, a similar increase in proliferation was observed in Slit1(-/-)/Slit2(-/-) mutant mice, suggesting that cell division is influenced by Slit-Robo signaling mechanisms. Morphometric analysis of migrating interneurons in Robo1(-/-), Robo2(-/-) and Slit1(-/-)/Slit2(-/-), but not in Slit1(-/-) mice, showed a differential increase in neuronal process length and branching suggesting that Slit-Robo signaling also plays an important role in the morphological differentiation of these neurons.
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MESH Headings
- Animals
- Biomarkers
- Calbindins
- Cell Culture Techniques
- Cell Differentiation
- Cell Movement
- Cell Proliferation
- Cells, Cultured
- Cerebral Cortex/cytology
- DNA, Complementary
- Electroporation
- Embryo, Mammalian
- Embryonic Stem Cells/chemistry
- Embryonic Stem Cells/metabolism
- Genetic Markers
- Genetic Vectors
- Genomic Library
- Immunohistochemistry
- Integrases/metabolism
- Intercellular Signaling Peptides and Proteins/genetics
- Intercellular Signaling Peptides and Proteins/metabolism
- Intercellular Signaling Peptides and Proteins/physiology
- Interneurons/cytology
- Interneurons/physiology
- Kinetics
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Mutation
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Nerve Tissue Proteins/physiology
- Receptors, Immunologic/genetics
- Receptors, Immunologic/metabolism
- Receptors, Immunologic/physiology
- S100 Calcium Binding Protein G/metabolism
- Selection, Genetic
- Signal Transduction
- Telencephalon/cytology
- Transfection
- Roundabout Proteins
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114 |
15
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Hivert B, Liu Z, Chuang CY, Doherty P, Sundaresan V. Robo1 and Robo2 are homophilic binding molecules that promote axonal growth. Mol Cell Neurosci 2002; 21:534-45. [PMID: 12504588 DOI: 10.1006/mcne.2002.1193] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/22/2022] Open
Abstract
In the present study we show that following transfection in 3T3 cells, human Robo1 and Robo2 stimulate neurite outgrowth from Robo-positive neurons (retinal neurons and olfactory neurons), but have no effect on Robo-negative neurons (cerebellar granule cells). The neurite outgrowth response was inhibited by an antibody raised against the first Ig domain of Robo1/2 or by soluble Robo-Fc chimera. Furthermore, we show that the extracellular domains of Robo1 and Robo2 are homophilic adhesion molecules that can also interact with each other. These data suggest a wider range of functions for the Robo family in the development of the nervous system and provide novel insights into the molecular basis for the phenotypes observed in Robo mutants in Drosophila, C. elegans, and zebrafish.
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23 |
113 |
16
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Sundaresan V, Jones JD, Ow DW, Ausubel FM. Klebsiella pneumoniae nifA product activates the Rhizobium meliloti nitrogenase promoter. Nature 1983; 301:728-32. [PMID: 6338395 DOI: 10.1038/301728a0] [Citation(s) in RCA: 101] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 01/19/2023]
Abstract
Bacteria in the genus Rhizobium normally fix nitrogen only when they interact with leguminous plants to produce on the roots a highly differentiated structure, the nodule, within which the bacteria differentiate into nitrogen-fixing bacteroids. By contrast, the enteric bacterium Klebsiella pneumoniae reduces nitrogen in a free-living state in conditions of low oxygen tension and deficiency of fixed nitrogen. In K. pneumoniae, the overall circuitry by which nitrogen-fixation (nif) genes are regulated has been elucidated. In response to ammonia starvation, the product of the glnG gene activates transcription of the nifLA operon; this activation is dependent on the product of glnF (ref. 4). The nifA gene product is in turn required for transcription of all the other nif genes, including the nifHDK operon which codes for the subunits of nitrogenase. In contrast, very little is known about the sequence of events involved in the regulated change in rhizobial nif gene expression associated with bacteroid differentiation. In the work described here, we identify the K. pneumoniae and Rhizobium meliloti nifHDK promoters by mapping the in vivo start points of transcription. By defining and comparing the DNA sequences of these two promoters, we find that they share an unexpected degree of homology. Further, by constructing fusions of each of the two promoters to the lacZ gene from Escherichia coli, we show that both promoters are activated by the product of the K. pneumoniae nifA gene.
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42 |
101 |
17
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Renaudin JP, Doonan JH, Freeman D, Hashimoto J, Hirt H, Inzé D, Jacobs T, Kouchi H, Rouzé P, Sauter M, Savouré A, Sorrell DA, Sundaresan V, Murray JA. Plant cyclins: a unified nomenclature for plant A-, B- and D-type cyclins based on sequence organization. PLANT MOLECULAR BIOLOGY 1996; 32:1003-1018. [PMID: 9002599 DOI: 10.1007/bf00041384] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Academic Contribution Register] [Indexed: 05/22/2023]
Abstract
The comparative analysis of a large number of plant cyclins of the A/B family has recently revealed that plants possess two distinct B-type groups and three distinct A-type groups of cyclins. Despite earlier uncertainties, this large-scale comparative analysis has allowed an unequivocal definition of plant cyclins into either A or B classes. We present here the most important results obtained in this study, and extend them to the case of plant D-type cyclins, in which three groups are identified. For each of the plant cyclin groups, consensus sequences have been established and a new, rational, plant-wide naming system is proposed in accordance with the guidelines of the Commission on Plant Gene Nomenclature. This nomenclature is based on the animal system indicating cyclin classes by an upper-case roman letter, and distinct groups within these classes by an arabic numeral suffix. The naming of plant cyclin classes is chosen to indicate homology to their closest animal class. The revised nomenclature of all described plant cyclins is presented, with their classification into groups CycA1, CycA2, CycA3, CycB1, CycB2, CycD1, CycD2 and CycD3.
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Review |
29 |
91 |
18
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Liu Z, Patel K, Schmidt H, Andrews W, Pini A, Sundaresan V. Extracellular Ig domains 1 and 2 of Robo are important for ligand (Slit) binding. Mol Cell Neurosci 2004; 26:232-40. [PMID: 15207848 DOI: 10.1016/j.mcn.2004.01.002] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Received: 10/10/2003] [Revised: 12/23/2003] [Accepted: 01/05/2004] [Indexed: 11/27/2022] Open
Abstract
Robo, the receptor for the midline repellent Slit, is a member of the cell adhesion molecule (CAM) Ig superfamily. We have recently demonstrated that members of the Robo family (Robo1 and Robo2) interact homophilically and heterophilically, thereby functioning to promote neurite outgrowth. Here, we describe a series of in vitro experiments to dissect the Robo ligand-interacting domains by deleting specific extracellular regions of the Robo1 molecule, generating a series of mutant proteins. Using these, we demonstrate that Ig domains 1 and 2 of Robo1 are important for Robo-Slit interaction and provide functional data using the Slit-mediated olfactory bulb repulsion assay. To investigate whether homophilic binding properties of Robo are domain specific, we used Robo1-Fc mutant deletion proteins in an aggregation assay and observed a reduction in homophilic binding when any one Ig or all the fibronectin domains were deleted, although homophilic binding was never completely abolished.
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21 |
91 |
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Sundaresan V, Chung G, Heppell-Parton A, Xiong J, Grundy C, Roberts I, James L, Cahn A, Bench A, Douglas J, Minna J, Sekido Y, Lerman M, Latif F, Bergh J, Li H, Lowe N, Ogilvie D, Rabbitts P. Homozygous deletions at 3p12 in breast and lung cancer. Oncogene 1998; 17:1723-9. [PMID: 9796701 DOI: 10.1038/sj.onc.1202103] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/09/2022]
Abstract
We have constructed a physical map of the region homozygously deleted in the U2020 cell line at 3p12, including the location of putative CpG islands. Adjacent to one of these islands, we have identified and cloned a new gene (DUTT1) and used probes from this gene to detect two other homozygous deletions occurring in lung and breast carcinomas: the smallest deletion is within the gene itself and would result in a truncated protein. The DUTT1 gene is a member of the neural cell adhesion molecule family, although its widespread expression suggests it plays a less specialized role compared to other members of the family.
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Kidner C, Sundaresan V, Roberts K, Dolan L. Clonal analysis of the Arabidopsis root confirms that position, not lineage, determines cell fate. PLANTA 2000; 211:191-199. [PMID: 10945213 DOI: 10.1007/s004250000284] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Academic Contribution Register] [Indexed: 05/23/2023]
Abstract
The cellular organization of the Arabidopsis thaliana (L.) Heynh. root meristem suggests that a regular pattern of cell divisions occurs in the root tip. Deviations from this pattern of division might be expected to disrupt the organization of cells and tissues in the root. A clonal analysis of the 3-d-old primary root meristem was carried out to determine if there is variability in division patterns, and if so to discover their effect on cellular organization in the root. Clones induced in the seedling meristem largely confirmed the predicted pattern of cell divisions. However, the cellular initials that normally give rise to the different cell files in the root were shown to exhibit some instability. For example, it was calculated that a lateral root cap/epidermal initial is displaced every 13 d. Furthermore, the existence of large marked clones that included more than two adjacent cell layers suggests that intrusive growth followed by cell division may occur at low frequency, perhaps in response to local cell deaths in the meristem. These findings support the view that even in plant organs with stereotypical cell division patterns, positional information is still the key determinant of cell fate.
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Renaudin JP, Colasanti J, Rime H, Yuan Z, Sundaresan V. Cloning of four cyclins from maize indicates that higher plants have three structurally distinct groups of mitotic cyclins. Proc Natl Acad Sci U S A 1994; 91:7375-9. [PMID: 8041798 PMCID: PMC44402 DOI: 10.1073/pnas.91.15.7375] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 01/28/2023] Open
Abstract
While a large number of cyclins have been described in animals and yeasts, very limited information is available regarding cyclins in plants. We describe here the isolation of cDNA clones encoding four putative mitotic cyclins from maize. All four cyclins were able to induce maturation of Xenopus oocytes, demonstrating that they can act as mitotic cyclins in this system. Northern analysis showed that all four cyclins were expressed only in actively dividing tissues and organs, with a stronger correlation between expression and mitotic activity than is observed with cdc2. The deduced protein sequences suggest that the four maize cyclins belong to the cyclin A and B families identified from animal and yeast studies but that they cannot be described easily as either A-type or B-type cyclins. However, comparison with previously cloned plant cyclins shows that cyclins in higher plants form three distinct structural groups that have been conserved in both monocotyledonous and dicotyledonous species and that cyclins from all three groups are present within a single plant species.
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Sundaresan V, Ausubel F. Nucleotide sequence of the gene coding for the nitrogenase iron protein from Klebsiella pneumoniae. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)69686-9] [Citation(s) in RCA: 70] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/29/2022] Open
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Abstract
We have prepared a robust polymer that can be used to measure glucose concentrations in complex biological media. At alkaline pH, the metal-complexing polymer binds glucose and instantly releases protons in proportion to the glucose concentration over a clinically relevant range (0 to 25 mM). The inexpensive polymer is sufficiently selective to provide an easily measurable response to glucose in porcine plasma. The polymer's ability to function at nonphysiological pH (at which the buffer capacity of biological samples is small) makes it possible to design simple and inexpensive sensing devices based on measurement of changes in proton concentration.
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Khanuja SP, Shasany AK, Pawar A, Lal R, Darokar M, Naqvi A, Rajkumar S, Sundaresan V, Lal N, Kumar S. Essential oil constituents and RAPD markers to establish species relationship in Cymbopogon Spreng. (Poaceae). BIOCHEM SYST ECOL 2005. [DOI: 10.1016/j.bse.2004.06.011] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/15/2022]
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Sundaresan V, Reeve JG, Stenning S, Stewart S, Bleehen NM. Neuroendocrine differentiation and clinical behaviour in non-small cell lung tumours. Br J Cancer 1991; 64:333-8. [PMID: 1654075 PMCID: PMC1977503 DOI: 10.1038/bjc.1991.301] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 12/28/2022] Open
Abstract
The present study examines the relationship between neuroendocrine (NE) differentiation and the clinical behaviour of non-small cell lung cancer (NSCLC). Retrospective (n = 315) and prospective (n = 44) cohorts of non-small cell tumours were obtained from surgically treated cases of lung cancer, comprising 218 squamous cell carcinomas, 65 adenocarcinomas, 51 adenosquamous carcinomas, and 25 large cell undifferentiated carcinomas. Paraffin wax embedded and fresh frozen tissue sections were stained for the NE markers neurone specific enolase, creatine kinase-BB, bombesin, neurotensin, chromogranin A, synaptophysin and UJ-13A. The expression of two or more markers was observed in 30% of cases, and was taken to identify NE-NSCLC. A statistically significant correlation between nodal status and NE differentiation (P = 0.05), and disease stage and NE differentiation (P = 0.04) was observed. However, there was no correlation between NE differentiation and survival. These findings suggest that NE-NSCLC, analogous to SCLC is more highly metastatic than non-NE-NSCLC.
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