PubMed Central (PMC3 - NLM DTD)
(2,081,148 recursos)
Archive of life sciences journal literature at the U.S. National Institutes of Health (NIH), developed and managed by NIH's National Center for Biotechnology Information (NCBI) in the National Library of Medicine (NLM).
Mostrando recursos 181 - 200 de 50,776
181.
Flowering of the Grass Lolium perenne. Effects of Vernalization and Long Days on Gibberellin Biosynthesis and Signaling1 - MacMillan, Colleen P.; Blundell, Cheryl A.; King, Rod W.
Almost 50 years ago, it was shown that gibberellin (GA) applications caused flowering in species normally responding to cold (vernalization) and long day (LD). The implication that GAs are involved with vernalization and LD responses is examined here with the grass Lolium perenne. This species has an obligatory requirement for exposure to both vernalization and LD for its flowering (inflorescence initiation). Specific effects of vernalization or LD on GA synthesis, content, and action have been documented using four treatment pairs: nonvernalized or vernalized plants exposed to short days (SDs) or LDs. Irrespective of vernalization status, exposure to two LDs increased...
185.
Plant Virus RNAs. Coordinated Recruitment of Conserved Host Functions by (+) ssRNA Viruses during Early Infection Events1 - Thivierge, Karine; Nicaise, Valérie; Dufresne, Philippe J.; Cotton, Sophie; Laliberté, Jean-François; Le Gall, Olivier; Fortin, Marc G.
Positive-sense single-stranded RNA viruses have developed strategies to exploit cellular resources at the expense of host mRNAs. The genomes of these viruses display a variety of structures at their 5? and 3? ends that differentiate them from cellular mRNAs. Despite this structural diversity, viral RNAs are still circularized by juxtaposition of their 5? and 3? ends, similar to the process used by cellular mRNAs. Also reminiscent of the mechanisms used by host mRNAs, translation of viral RNAs involves the recruitment of translation initiation factors. However, the roles played by these factors likely differ from those played by cellular mRNAs. In...
186.
Effect of Temperature on Geminivirus-Induced RNA Silencing in Plants1 - Chellappan, Padmanabhan; Vanitharani, Ramachandran; Ogbe, Francis; Fauquet, Claude M.
Short-interfering RNAs (siRNAs), the molecular markers of posttranscriptional gene silencing (PTGS), are powerful tools that interfere with gene expression and counter virus infection both in plants and animals. Here, we report the effect of temperature on geminivirus-induced gene silencing by quantifying virus-derived siRNAs and by evaluating their distribution along the virus genome for isolates of five species of cassava geminiviruses in cassava (Manihot esculenta, Crantz) and Nicotiana benthamiana. Cassava geminivirus-induced RNA silencing increased by raising the temperature from 25°C to 30°C, with the appearance of less symptomatic newly developed leaves, irrespective of the nature of the virus. Consequently, nonrecovery-type geminiviruses...
187.
An RNA-Dependent RNA Polymerase Prevents Meristem Invasion by Potato Virus X and Is Required for the Activity But Not the Production of a Systemic Silencing Signal1[w] - Schwach, Frank; Vaistij, Fabian E.; Jones, Louise; Baulcombe, David C.
One of the functions of RNA silencing in plants is antiviral defense. A hallmark of RNA silencing is spreading of the silenced state through the plant. Little is known about the nature of the systemic silencing signal and the proteins required for its production, transport, and reception in plant tissues. Here, we show that the RNA-dependent RNA polymerase RDR6 in Nicotiana benthamiana is involved in defense against potato virus X at the level of systemic spreading and in exclusion of the virus from the apical growing point. It has no effect on primary replication and cell-to-cell movement of the virus...
188.
The Tobacco Mosaic Virus 126-Kilodalton Protein, a Constituent of the Virus Replication Complex, Alone or within the Complex Aligns with and Traffics along Microfilaments1[w] - Liu, Jian-Zhong; Blancaflor, Elison B.; Nelson, Richard S.
Virus-induced cytoplasmic inclusion bodies (referred to as virus replication complexes [VRCs]) consisting of virus and host components are observed in plant cells infected with tobacco mosaic virus, but the components that modulate their form and function are not fully understood. Here, we show that the tobacco mosaic virus 126-kD protein fused with green fluorescent protein formed cytoplasmic bodies (126-bodies) in the absence of other viral components. Using mutant 126-kD:green fluorescent fusion proteins and viral constructs expressing the corresponding mutant 126-kD proteins, it was determined that the size of the 126-bodies and the corresponding VRCs changed in synchrony for each 126-kD...
189.
Effects of Calreticulin on Viral Cell-to-Cell Movement1 - Chen, Min-Huei; Tian, Guo-Wei; Gafni, Yedidya; Citovsky, Vitaly
Cell-to-cell tobacco mosaic virus movement protein (TMV MP) mediates viral spread between the host cells through plasmodesmata. Although several host factors have been shown to interact with TMV MP, none of them coresides with TMV MP within plasmodesmata. We used affinity purification to isolate a tobacco protein that binds TMV MP and identified it as calreticulin. The interaction between TMV MP and calreticulin was confirmed in vivo and in vitro, and both proteins were shown to share a similar pattern of subcellular localization to plasmodesmata. Elevation of the intracellular levels of calreticulin severely interfered with plasmodesmal targeting of TMV MP,...
190.
The Potato Virus X TGBp2 Movement Protein Associates with Endoplasmic Reticulum-Derived Vesicles during Virus Infection1 - Ju, Ho-Jong; Samuels, Timmy D.; Wang, Yuh-Shuh; Blancaflor, Elison; Payton, Mark; Mitra, Ruchira; Krishnamurthy, Konduru; Nelson, Richard S.; Verchot-Lubicz, Jeanmarie
The green fluorescent protein (GFP) gene was fused to the potato virus X (PVX) TGBp2 gene, inserted into either the PVX infectious clone or pRTL2 plasmids, and used to study protein subcellular targeting. In protoplasts and plants inoculated with PVX-GFP:TGBp2 or transfected with pRTL2-GFP:TGBp2, fluorescence was mainly in vesicles and the endoplasmic reticulum (ER). During late stages of virus infection, fluorescence became increasingly cytosolic and nuclear. Protoplasts transfected with PVX-GFP:TGBp2 or pRTL2-GFP:TGBp2 were treated with cycloheximide and the decline of GFP fluorescence was greater in virus-infected protoplasts than in pRTL2-GFP:TGBp2-transfected protoplasts. Thus, protein instability is enhanced in virus-infected protoplasts, which...
193.
RNA Silencing of Single and Multiple Members in a Gene Family of Rice1[w] - Miki, Daisuke; Itoh, Rika; Shimamoto, Ko
RNA silencing with inverted repeat (IR) constructs has been used to suppress gene expression in various organisms. However, the transitive RNA-silencing effect described in plants may preclude the use of RNA silencing for a gene family. Here, we show that, in rice (Oryza sativa), transitive RNA silencing (spreading of double-stranded RNA along the target mRNA) occurred with the green fluorescent protein transgene but not with the endogenous phytoene desaturase gene. We fused IR copies of unique 3? untranslated regions derived from the rice OsRac gene family to a strong promoter and stably introduced them into rice. Each of the seven...
194.
Dragon Plant Biology Explorer. A Text-Mining Tool for Integrating Associations between Genetic and Biochemical Entities with Genome Annotation and Biochemical Terms Lists[w] - Bajic, Vladimir B.; Veronika, Merlin; Veladandi, Pardha Sarathi; Meka, Archana; Heng, Mok-Wei; Rajaraman, Kanagasabai; Pan, Hong; Swarup, Sanjay
We introduce a tool for text mining, Dragon Plant Biology Explorer (DPBE) that integrates information on Arabidopsis (Arabidopsis thaliana) genes with their functions, based on gene ontologies and biochemical entity vocabularies, and presents the associations as interactive networks. The associations are based on (1) user-provided PubMed abstracts; (2) a list of Arabidopsis genes compiled by The Arabidopsis Information Resource; (3) user-defined combinations of four vocabulary lists based on the ones developed by the general, plant, and Arabidopsis GO consortia; and (4) three lists developed here based on metabolic pathways, enzymes, and metabolites derived from AraCyc, BRENDA, and other metabolism databases....
195.
Functional Analysis of the Pyrimidine de Novo Synthesis Pathway in Solanaceous Species1 - Schröder, Michael; Giermann, Norbert; Zrenner, Rita
Pyrimidines are particularly important in dividing tissues as building blocks for nucleic acids, but they are equally important for many biochemical processes, including sucrose and cell wall polysaccharide metabolism. In recent years, the molecular organization of nucleotide biosynthesis in plants has been analyzed. Here, we present a functional analysis of the pyrimidine de novo synthesis pathway. Each step in the pathway was investigated using transgenic plants with reduced expression of the corresponding gene to identify controlling steps and gain insights into the phenotypic and metabolic consequences. Inhibition of expression of 80% based on steady-state mRNA level did not lead to...
196.
Characterization of Vacuolar Transport of the Endogenous Alkaloid Berberine in Coptis japonica1 - Otani, Mihoko; Shitan, Nobukazu; Sakai, Kyoko; Martinoia, Enrico; Sato, Fumihiko; Yazaki, Kazufumi
Alkaloids comprise one of the largest groups of plant secondary metabolites. Many of them exhibit strong biological activities, and, in most cases, they are accumulated in the central vacuole of alkaloid-producing plants after synthesis. However, the mechanisms involved in alkaloid transport across the tonoplast are only poorly understood. In this study, we analyzed the vacuolar transport mechanism of an isoquinoline alkaloid, berberine, which is produced and accumulated in the vacuole of cultured cells of Coptis japonica. The characterization of berberine transport using intact vacuoles and a tonoplast vesicle system showed that berberine uptake was stimulated by Mg/ATP, as well as...
197.
Molecular Identification and Characterization of the Arabidopsis ?3,5,?2,4-Dienoyl-Coenzyme A Isomerase, a Peroxisomal Enzyme Participating in the ?-Oxidation Cycle of Unsaturated Fatty Acids1 - Goepfert, Simon; Vidoudez, Charles; Rezzonico, Enea; Hiltunen, J. Kalervo; Poirier, Yves
Degradation of unsaturated fatty acids through the peroxisomal ?-oxidation pathway requires the participation of auxiliary enzymes in addition to the enzymes of the core ?-oxidation cycle. The auxiliary enzyme ?3,5,?2,4-dienoyl-coenzyme A (CoA) isomerase has been well studied in yeast (Saccharomyces cerevisiae) and mammals, but no plant homolog had been identified and characterized at the biochemical or molecular level. A candidate gene (At5g43280) was identified in Arabidopsis (Arabidopsis thaliana) encoding a protein showing homology to the rat (Rattus norvegicus) ?3,5,?2,4-dienoyl-CoA isomerase, and possessing an enoyl-CoA hydratase/isomerase fingerprint as well as aspartic and glutamic residues shown to be important for catalytic activity...
198.
Functional Redundancy of AtFtsH Metalloproteases in Thylakoid Membrane Complexes1 - Yu, Fei; Park, Sungsoon; Rodermel, Steven R.
FtsH is an ATP-dependent metalloprotease found in bacteria, mitochondria, and plastids. Arabidopsis (Arabidopsis thaliana) contains 12 AtFtsH proteins, three in the mitochondrion and nine in the chloroplast. Four of the chloroplast FtsH proteins are encoded by paired members of closely related genes (AtFtsH1 and 5, and AtFtsH2 and 8). We have previously reported that AtFtsH2 and 8 are interchangeable components of AtFtsH complexes in the thylakoid membrane. In this article, we show that the var1 variegation mutant, which is defective in AtFtsH5, has a coordinate reduction in the AtFtsH2 and 8 pair, and that the levels of both pairs are...
199.
Arabidopsis Peroxin 16 Coexists at Steady State in Peroxisomes and Endoplasmic Reticulum1 - Karnik, Sheetal K.; Trelease, Richard N.
Homologs of peroxin 16 genes (PEX16) have been identified only in Yarrowia lipolytica, humans (Homo sapiens), and Arabidopsis (Arabidopsis thaliana). The Arabidopsis gene (AtPEX16), previously reported as the SSE1 gene, codes for a predicted 42-kD membrane peroxin protein (AtPex16p). Lin et al. (Y. Lin, J.E. Cluette-Brown, H.M. Goodman [2004] Plant Physiol 135: 814827) reported that SSE1/AtPEX16 was essential for endoplasmic reticulum (ER)-dependent oil and protein body biogenesis in peroxisome-deficient maturing seeds and likely also was involved in peroxisomal biogenesis based on localization of stably expressed green fluorescent protein::AtPex16p in peroxisomes of Arabidopsis plants. In this study with Arabidopsis suspension-cultured cells,...
200.
Analysis of the Rice Mutant dwarf and gladius leaf 1. Aberrant Katanin-Mediated Microtubule Organization Causes Up-Regulation of Gibberellin Biosynthetic Genes Independently of Gibberellin Signaling - Komorisono, Masahiko; Ueguchi-Tanaka, Miyako; Aichi, Ikuko; Hasegawa, Yasuko; Ashikari, Motoyuki; Kitano, Hidemi; Matsuoka, Makoto; Sazuka, Takashi
Molecular genetic studies of plant dwarf mutants have indicated that gibberellin (GA) and brassinosteroid (BR) are two major factors that determine plant height; dwarf mutants that are caused by other defects are relatively rare, especially in monocot species. Here, we report a rice (Oryza sativa) dwarf mutant, dwarf and gladius leaf 1 (dgl1), which exhibits only minimal response to GA and BR. In addition to the dwarf phenotype, dgl1 produces leaves with abnormally rounded tip regions. Positional cloning of DGL1 revealed that it encodes a 60-kD microtubule-severing katanin-like protein. The protein was found to be important in cell elongation and...
181.
