PubMed Central (PMC3 - NLM DTD)
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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 21 - 40 de 50,776
21.
Mutants of Arabidopsis Lacking a Chloroplastic Isoamylase Accumulate Phytoglycogen and an Abnormal Form of Amylopectin1[w] - Wattebled, Fabrice; Dong, Ying; Dumez, Sylvain; Delvallé, David; Planchot, Véronique; Berbezy, Pierre; Vyas, Darshna; Colonna, Paul; Chatterjee, Manash; Ball, Steven; D'Hulst, Christophe
Mutant lines defective for each of the four starch debranching enzyme (DBE) genes (AtISA1, AtISA2, AtISA3, and AtPU1) detected in the nuclear genome of Arabidopsis (Arabidopsis thaliana) were produced and analyzed. Our results indicate that both AtISA1 and AtISA2 are required for the production of a functional isoamylase-type of DBE named Iso1, the major isoamylase activity found in leaves. The absence of Iso1 leads to an 80% decrease in the starch content in both lines and to the accumulation of water-soluble polysaccharides whose structure is similar to glycogen. In addition, the residual amylopectin structure in the corresponding mutant lines displays...
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Functional Characterization and Expression Analysis of a Gene, OsENT2, Encoding an Equilibrative Nucleoside Transporter in Rice Suggest a Function in Cytokinin Transport1 - Hirose, Naoya; Makita, Nobue; Yamaya, Tomoyuki; Sakakibara, Hitoshi
We identified four genes for potential equilibrative nucleoside transporters (ENTs) from rice (Oryza sativa; designated OsENT1 through OsENT4). Growth analysis of budding yeast (Saccharomyces cerevisiae) cells expressing OsENTs showed that OsENT2 transported adenosine and uridine with high affinity (adenosine, Km = 3.0 ?m; uridine, Km = 0.7 ?m). Purine or pyrimidine nucleosides and 2?-deoxynucleosides strongly inhibited adenosine transport via OsENT2, suggesting that OsENT2 possesses broad substrate specificity. OsENT2-mediated adenosine transport was resistant to the typical inhibitors of mammalian ENTs, nitrobenzylmercaptopurine ribonucleoside, dilazep, and dipyridamole. The transport activity was maximal at pH 5.0 and decreased slightly at lower as well as...
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Localization of Soluble ?-Carbonic Anhydrase in the Marine Diatom Phaeodactylum tricornutum. Sorting to the Chloroplast and Cluster Formation on the Girdle Lamellae1[w] - Tanaka, Yuji; Nakatsuma, Daisuke; Harada, Hisashi; Ishida, Maki; Matsuda, Yusuke
A ?-carbonic anhydrase (CA) in the marine diatom Phaeodactylum tricornutum (PtCA1) is encoded by the nuclear genome. This enzyme was previously found to be important for the operation of photosynthesis with a high affinity for dissolved inorganic carbon. A cDNA sequence that encodes PtCA1 (ptca1) was shown to possess a presequence of 138 bp (pre138), which encodes an N-terminal sequence of 46 amino acids (Pre46AA) that does not exist in the mature PtCA1. In this study, pre138 was ligated with the enhanced green fluorescent protein (GFP) gene (egfp), and introduced into P. tricornutum by microprojectile bombardment. Subsequently, the expressed Pre46AA-GFP...
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Identification and Characterization of Endoplasmic Reticulum-Associated Degradation Proteins Differentially Affected by Endoplasmic Reticulum Stress1 - Kirst, Mariana E.; Meyer, David J.; Gibbon, Bryan C.; Jung, Rudolf; Boston, Rebecca S.
The disposal of misfolded proteins from the lumen of the endoplasmic reticulum (ER) is one of the quality control mechanisms present in the protein secretory pathway. Through ER-associated degradation, misfolded substrates are targeted to the cytosol where they are degraded by the proteasome. We have identified four maize (Zea mays) Der1-like genes (Zm Derlins) that encode homologs of Der1p, a yeast (Saccharomyces cerevisiae) protein implicated in ER-associated degradation. Zm Derlins are capable of functionally complementing a yeast Der1 deletion mutant. Such complementation indicates that the Der1p function is conserved among species. Zm Derlin genes are expressed at low levels throughout...
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A Novel Short-Root Gene Encodes a Glucosamine-6-Phosphate Acetyltransferase Required for Maintaining Normal Root Cell Shape in Rice1 - Jiang, Huawu; Wang, Shaomin; Dang, Lei; Wang, Shoufeng; Chen, Hanmin; Wu, Yunrong; Jiang, Xinhang; Wu, Ping
Glycosylation is a posttranslational modification occurring in many secreted and membrane-associated proteins in eukaryotes. It plays important roles in both physiological and pathological processes. Most of these protein modifications depend on UDP-N-acetylglucosamine. In this study, a T-DNA insertional rice (Oryza sativa) mutant exhibiting a temperature-sensitive defect in root elongation was isolated. Genetic and molecular analysis indicated that the mutated phenotype was caused by loss of function of a gene encoding a glucosamine-6-P acetyltransferase (designated OsGNA1), which is involved in de novo UDP-N-acetylglucosamine biosynthesis. The aberrant root morphology of the gna1 mutant includes shortening of roots, disruption of microtubules, and shrinkage...
26.
Molecular Cloning of GA 2-Oxidase3 from Spinach and Its Ectopic Expression in Nicotiana sylvestris1 - Lee, Dong Ju; Zeevaart, Jan A.D.
Previous work has shown that 13-hydroxylated gibberellins (GAs) are predominant in the long-day (LD) plant spinach (Spinacia oleracea; GA53, GA44, GA19, GA20, GA1, GA8, and GA29). Also present in spinach are 2?-hydroxylated C20-GAs: GA97, GA98, GA99, and GA110. Levels of the most abundant GA, GA97, decreased when plants were transferred from short photoperiods (SD) to LD. When [14C]GA53 was fed to spinach plants, more GA53 was converted to GA97 in SD than in LD, and more radioactive GA20 was formed in LD than in SD. SoGA2ox3, encoding a GA 2-oxidase, was isolated from spinach. The recombinant protein converted only two...
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Ethylene-Regulated Floral Volatile Synthesis in Petunia Corollas1[w] - Underwood, Beverly A.; Tieman, Denise M.; Shibuya, Kenichi; Dexter, Richard J.; Loucas, Holly M.; Simkin, Andrew J.; Sims, Charles A.; Schmelz, Eric A.; Klee, Harry J.; Clark, David G.
In many flowering plants, such as petunia (Petunia × hybrida), ethylene produced in floral organs after pollination elicits a series of physiological and biochemical events, ultimately leading to senescence of petals and successful fertilization. Here, we demonstrate, using transgenic ethylene insensitive (44568) and Mitchell Diploid petunias, that multiple components of emission of volatile organic compounds (VOCs) are regulated by ethylene. Expression of benzoic acid/salicylic acid carboxyl methyltransferase (PhBSMT1 and 2) mRNA is temporally and spatially down-regulated in floral organs in a manner consistent with current models for postpollination ethylene synthesis in petunia corollas. Emission of methylbenzoate and other VOCs after...
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Ethylene Insensitivity Conferred by the Green-ripe and Never-ripe 2 Ripening Mutants of Tomato1 - Barry, Cornelius S.; McQuinn, Ryan P.; Thompson, Andrew J.; Seymour, Graham B.; Grierson, Donald; Giovannoni, James J.
The ripening of a fleshy fruit represents the summation of an array of biochemical processes that are regulated by interactions between developmental programs and environmental inputs. Analysis of tomato (Solanum lycopersicum) mutants and inhibitor studies indicate that ethylene is necessary for full development of the ripening program of climacteric fruit such as tomato, yet ethylene alone is not sufficient. This suggests that an interaction between ethylene and nonethylene (or developmental) pathways mediates ripening. In this study, we have examined the physiological basis for ripening inhibition of the dominant Green-ripe (Gr) and Never-ripe 2 (Nr-2) mutants of tomato. Our data suggest...
29.
The Pivotal Roles of the Plant S-Adenosylmethionine Decarboxylase 5? Untranslated Leader Sequence in Regulation of Gene Expression at the Transcriptional and Posttranscriptional Levels1 - Hu, Wen-Wei; Gong, Haibiao; Pua, Eng Chong
S-Adenosylmethionine decarboxylase (SAMDC; EC 4.1.1.50) is a key rate-limiting enzyme located in the polyamine biosynthesis pathway. When compared with other organisms, the plant SAMDC genes possess some distinct features because they are devoid of introns in the main open reading frame (ORF) but have an intron(s) in their 5? untranslated leader sequences, in which two overlapping tiny and small upstream ORFs (uORFs) are present. Our results show that the presence of the 5? leader sequence plays important roles in transcriptional and posttranscriptional regulation of SAMDC expression. This sequence may help to keep the transcript of its downstream cistron at a...
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Citrate Secretion Coupled with the Modulation of Soybean Root Tip under Aluminum Stress. Up-Regulation of Transcription, Translation, and Threonine-Oriented Phosphorylation of Plasma Membrane H+-ATPase1 - Shen, Hong; He, Long Fei; Sasaki, Takayuki; Yamamoto, Yoko; Zheng, Shao Jian; Ligaba, Ayalew; Yan, Xiao Long; Ahn, Sung Ju; Yamaguchi, Mineo; Sasakawa, Hideo; Matsumoto, Hideaki
The aluminum (Al)-induced secretion of citrate has been regarded as an important mechanism for Al resistance in soybean (Glycine max). However, the mechanism of how Al induces citrate secretion remains unclear. In this study, we investigated the regulatory role of plasma membrane H+-ATPase on the Al-induced secretion of citrate from soybean roots. Experiments performed with plants grown in full nutrient solution showed that Al-induced activity of plasma membrane H+-ATPase paralleled secretion of citrate. Vanadate and fusicoccin, an inhibitor and an activator, respectively, of plasma membrane H+-ATPase, exerted inhibitory and stimulatory effects on the Al-induced secretion of citrate. Higher activity of...
31.
Immobilization of Aluminum with Phosphorus in Roots Is Associated with High Aluminum Resistance in Buckwheat1 - Zheng, Shao Jian; Yang, Jian Li; He, Yun Feng; Yu, Xue Hui; Zhang, Lei; You, Jiang Feng; Shen, Ren Fang; Matsumoto, Hideaki
Oxalic acid secretion from roots is considered to be an important mechanism for aluminum (Al) resistance in buckwheat (Fygopyrum esculentum Moench). Nonetheless, only a single Al-resistant buckwheat cultivar was used to investigate the significance of oxalic acid in detoxifying Al. In this study, we investigated two buckwheat cultivars, Jiangxi (Al resistant) and Shanxi (Al sensitive), which showed significant variation in their resistance to Al stress. In the presence of 0 to 100 ?m Al, the inhibition of root elongation was greater in Shanxi than that in Jiangxi, and the Al content of root apices (010 mm) was much lower in...
32.
Systems Rebalancing of Metabolism in Response to Sulfur Deprivation, as Revealed by Metabolome Analysis of Arabidopsis Plants1[w] - Nikiforova, Victoria J.; Kopka, Joachim; Tolstikov, Vladimir; Fiehn, Oliver; Hopkins, Laura; Hawkesford, Malcolm J.; Hesse, Holger; Hoefgen, Rainer
Sulfur is an essential macroelement in plant and animal nutrition. Plants assimilate inorganic sulfate into two sulfur-containing amino acids, cysteine and methionine. Low supply of sulfate leads to decreased sulfur pools within plant tissues. As sulfur-related metabolites represent an integral part of plant metabolism with multiple interactions, sulfur deficiency stress induces a number of adaptive responses, which must be coordinated. To reveal the coordinating network of adaptations to sulfur deficiency, metabolite profiling of Arabidopsis has been undertaken. Gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry techniques revealed the response patterns of 6,023 peaks of nonredundant ion traces and relative concentration levels...
33.
The LPB1 Gene Is Important for Acclimation of Chlamydomonas reinhardtii to Phosphorus and Sulfur Deprivation1[w] - Chang, Chiung-Wen; Moseley, Jeffrey L.; Wykoff, Dennis; Grossman, Arthur R.
Organisms exhibit a diverse set of responses when exposed to low-phosphate conditions. Some of these responses are specific for phosphorus limitation, including responses that enable cells to efficiently scavenge phosphate from internal and external stores via the production of high-affinity phosphate transporters and the synthesis of intracellular and extracellular phosphatases. Other responses are general and occur under a number of different environmental stresses, helping coordinate cellular metabolism and cell division with the growth potential of the cell. In this article, we describe the isolation and characterization of a mutant of Chlamydomonas reinhardtii, low-phosphate bleaching (lpb1), which dies more rapidly than...
34.
Antifreeze Proteins Modify the Freezing Process In Planta12 - Griffith, Marilyn; Lumb, Chelsey; Wiseman, Steven B.; Wisniewski, Michael; Johnson, Robert W.; Marangoni, Alejandro G.
During cold acclimation, winter rye (Secale cereale L. cv Musketeer) plants accumulate antifreeze proteins (AFPs) in the apoplast of leaves and crowns. The goal of this study was to determine whether these AFPs influence survival at subzero temperatures by modifying the freezing process or by acting as cryoprotectants. In order to inhibit the growth of ice, AFPs must be mobile so that they can bind to specific sites on the ice crystal lattice. Guttate obtained from cold-acclimated winter rye leaves exhibited antifreeze activity, indicating that the AFPs are free in solution. Infrared video thermography was used to observe freezing in...
35.
Arabidopsis CBF3/DREB1A and ABF3 in Transgenic Rice Increased Tolerance to Abiotic Stress without Stunting Growth1[w] - Oh, Se-Jun; Song, Sang Ik; Kim, Youn Shic; Jang, Hyun-Jun; Kim, Soo Young; Kim, Minjeong; Kim, Yeon-Ki; Nahm, Baek Hie; Kim, Ju-Kon
Rice (Oryza sativa), a monocotyledonous plant that does not cold acclimate, has evolved differently from Arabidopsis (Arabidopsis thaliana), which cold acclimates. To understand the stress response of rice in comparison with that of Arabidopsis, we developed transgenic rice plants that constitutively expressed CBF3/DREB1A (CBF3) and ABF3, Arabidopsis genes that function in abscisic acid-independent and abscisic acid-dependent stress-response pathways, respectively. CBF3 in transgenic rice elevated tolerance to drought and high salinity, and produced relatively low levels of tolerance to low-temperature exposure. These data were in direct contrast to CBF3 in Arabidopsis, which is known to function primarily to enhance freezing tolerance....
36.
Transcriptional Profiling of Sorghum Induced by Methyl Jasmonate, Salicylic Acid, and Aminocyclopropane Carboxylic Acid Reveals Cooperative Regulation and Novel Gene Responses1[w] - Salzman, Ron A.; Brady, Jeff A.; Finlayson, Scott A.; Buchanan, Christina D.; Summer, Elizabeth J.; Sun, Feng; Klein, Patricia E.; Klein, Robert R.; Pratt, Lee H.; Cordonnier-Pratt, Marie-Michèle; Mullet, John E.
We have conducted a large-scale study of gene expression in the C4 monocot sorghum (Sorghum bicolor) L. Moench cv BTx623 in response to the signaling compounds salicylic acid (SA), methyl jasmonate (MeJA), and the ethylene precursor aminocyclopropane carboxylic acid. Expression profiles were generated from seedling root and shoot tissue at 3 and 27 h, using a microarray containing 12,982 nonredundant elements. Data from 102 slides and quantitative reverse transcription-PCR data on mRNA abundance from 171 genes were collected and analyzed and are here made publicly available. Numerous gene clusters were identified in which expression was correlated with particular signaling compound...
37.
Unique Translation Initiation at the Second AUG Codon Determines Mitochondrial Localization of the Phage-Type RNA Polymerases in the Moss Physcomitrella patens1 - Kabeya, Yukihiro; Sato, Naoki
The nuclear genome of the moss Physcomitrella patens contains two genes encoding phage-type RNA polymerases (PpRPOT1 and PpRPOT2). Each of the PpRPOT1 and PpRPOT2 transcripts possesses two in-frame AUG codons at the 5? terminus that could act as a translational initiation site. Observation of transient and stable Physcomitrella transformants expressing the 5? terminus of each PpRPOT cDNA fused with the green fluorescent protein gene suggested that both PpRPOT1 and PpRPOT2 are not translated from the first (upstream) AUG codon in the natural context but translated from the second (downstream) one, and that these enzymes are targeted only to mitochondria, although...
38.
Nematode Infection Triggers the de Novo Formation of Unloading Phloem That Allows Macromolecular Trafficking of Green Fluorescent Protein into Syncytia1 - Hoth, Stefan; Schneidereit, Alexander; Lauterbach, Christian; Scholz-Starke, Joachim; Sauer, Norbert
Syncytial feeding complexes induced by the cyst nematode Heterodera schachtii represent strong metabolic sinks for photoassimilates. These newly formed structures were described to be symplastically isolated from the surrounding root tissue and their mechanism of carbohydrate import has repeatedly been under investigation. Here, we present analyses of the symplastic connectivity between the root phloem and these syncytia in nematode-infected Arabidopsis (Arabidopsis thaliana) plants expressing the gene of the green fluorescent protein (GFP) or of different GFP fusions under the control of the companion cell (CC)-specific AtSUC2 promoter. In the same plants, phloem differentiation during syncytium formation was monitored using cell-specific...
39.
A Stilbene Synthase Gene (SbSTS1) Is Involved in Host and Nonhost Defense Responses in Sorghum1 - Yu, Christine K.Y.; Springob, Karin; Schmidt, Jürgen; Nicholson, Ralph L.; Chu, Ivan K.; Yip, Wing Kin; Lo, Clive
A chalcone synthase (CHS)-like gene, SbCHS8, with high expressed sequence tag abundance in a pathogen-induced cDNA library, was identified previously in sorghum (Sorghum bicolor). Genomic Southern analysis revealed that SbCHS8 represents a single-copy gene. SbCHS8 expression was induced in sorghum mesocotyls following inoculation with Cochliobolus heterotrophus and Colletotrichum sublineolum, corresponding to nonhost and host defense responses, respectively. However, the induction was delayed by approximately 24 h when compared to the expression of at least one of the other SbCHS genes. In addition, SbCHS8 expression was not induced by light and did not occur in a tissue-specific manner. SbCHS8, together with...
40.
Identification of a Long-Chain Polyunsaturated Fatty Acid Acyl-Coenzyme A Synthetase from the Diatom Thalassiosira pseudonana1 - Tonon, Thierry; Qing, Renwei; Harvey, David; Li, Yi; Larson, Tony Robert; Graham, Ian Alexander
The draft genome of the diatom Thalassiosira pseudonana was searched for DNA sequences showing homology with long-chain acyl-coenzyme A synthetases (LACSs), since the corresponding enzyme may play a key role in the accumulation of health-beneficial polyunsaturated fatty acids (PUFAs) in triacylglycerol. Among the candidate genes identified, an open reading frame named TplacsA was found to be full length and constitutively expressed during cell cultivation. The predicted amino acid sequence of the corresponding protein, TpLACSA, exhibited typical features of acyl-coenzyme A (acyl-CoA) synthetases involved in the activation of long-chain fatty acids. Feeding experiments carried out in yeast (Saccharomyces cerevisiae) transformed with...
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