RESUMEN
BACKGROUND: Although radiographs have been widely used in the evaluation of patients with suspected bone tumors, the lack of an objective radiological assessment method leads to a challenge in reaching correct diagnosis. The study aimed to propose a Radiological Evaluation Score for Bone Tumors (REST) which includes eight radiological factors [characteristics, content, cortical breach, distinctiveness, distribution, periosteal reaction, fracture, and soft tissue swelling] to form a single score along with its validation by multidisciplinary observers. METHODS: We reviewed the radiographs of 100 patients with a primary bone tumor which were selected at random from the database between January 2017 and January 2019 of a tertiary cancer center. Four reviewers (two orthopedic oncologists and two surgical oncologists) independently assessed the radiographs, based on the reporting system of REST. We constituted two groups according to the probable diagnosis of bone tumor (suspected benign tumor and suspected malignant tumor). RESULTS: The mean score in the suspected benign tumor group was 1.1 (range 0-3, 95% CI 0.8-1.3) and in malignant tumor group was 6.1 (range 2-8, 95% CI 5.8-6.4). A receiver operator characteristic (ROC) curve for REST was with a cutoff of 3.5, with the most diagnostic value area under curve (AUC) of 0.99. The sensitivity was 98% and specificity was 100% with a positive predictive value of 100% and a negative predictive value of 98%. The inter-observer correlation coefficient was 0.985 (p value < 0.05), and Fleiss kappa value for the prediction of the benign or malignant lesion was 0.97 (p value < 0.05). The characteristics and content of tumor, cortical erosion, distinctiveness, distribution, periosteal reaction, and soft tissue mass had a significant correlation with the aggressiveness of bone lesion p value < 0.05. CONCLUSIONS: The Radiological Evaluation Score for Bone Tumors (REST) is a structured reporting and objective method for the assessment of radiographs in patients with suspected bone tumors. This method is a reliable and helpful tool for clinicians in their outdoor patient department to differentiate a radiograph of a suspected benign tumor from a malignant bone tumor.
Asunto(s)
Neoplasias Óseas , Humanos , Neoplasias Óseas/diagnóstico , Radiografía , Valor Predictivo de las Pruebas , Estudios RetrospectivosRESUMEN
INTRODUCTION: We propose a ''A to Z RAM (Radiograph Assessment Method)'' for evaluation of Radiograph of patients with a suspected bone tumour. METHODS: In the current study, ten radiological features with letters 'A, B, C, D, E, F and Z' were used and which included the age of the patient, involved part of the bone, characteristics, content, distinctiveness, the exterior of the bone, fracture, and zone of transition. Four independent observers (orthopaedic oncologists and surgical oncologists) evaluated a set of 30 radiographs of bone tumour selected at random from our hospital database based on A to Z RAM. We classified the lesions into two groups according to the traffic signal system; Green (suspected benign lesion) and Red (suspected malignant lesion). RESULTS: There were 18 (60%) benign bone lesions and 12 (40%) malignant lesions in the current study. 91.6% of malignant tumours and 88.8% of the benign tumours were identified correctly by the four observers. The inter-observer variability with Fleiss kappa was 0.884 (95% CI 0.7-1.03 p-value < 0.05), suggestive of agreement not by chance. These radiographs were again reassessed by the four observers after 3 months. The interobserver variability by Fleiss kappa was 1.0 (95% CI 0.8-1.1) suggesting complete agreement amongst the observers. Both orthopaedic oncologists had intra-observer kappa as 1.0 each and both surgical oncologists had 0.795 and 0.930 respectively. CONCLUSION: The proposed A to Z RAM is an easy to use and reproducible method for reviewing radiographs in the out-patient department along with clinical findings for better management of patients with suspected bone lesions. The A to Z RAM can be a medical triage tool and subdivide bone lesions into two subgroups i.e. suspected benign lesion with a suggestion of further investigations with MRI and biopsy and suspected malignant lesion with a suggestion of MRI or early referral to a tertiary cancer center with expertise in orthopaedic oncology. IMPLICATIONS FOR PRACTICE: The A to Z RAM (Radiologic Assessment Method) is a reproducible method for reviewing radiographs in the out-patient department and can be an aid for better management of patients. A to Z RAM is useful as a medical triage system, subdividing patients according to the probable diagnosis into a suspected benign lesion and suspected malignant lesion.
Asunto(s)
Neoplasias Óseas , Fracturas Óseas , Neoplasias Óseas/diagnóstico por imagen , Humanos , Variaciones Dependientes del Observador , Radiografía , TriajeRESUMEN
BACKGROUND AND AIMS: Bioenergy crops are central to climate mitigation strategies that utilize biogenic carbon, such as BECCS (bioenergy with carbon capture and storage), alongside the use of biomass for heat, power, liquid fuels and, in the future, biorefining to chemicals. Several promising lignocellulosic crops are emerging that have no food role - fast-growing trees and grasses - but are well suited as bioenergy feedstocks, including Populus, Salix, Arundo, Miscanthus, Panicum and Sorghum. SCOPE: These promising crops remain largely undomesticated and, until recently, have had limited germplasm resources. In order to avoid competition with food crops for land and nature conservation, it is likely that future bioenergy crops will be grown on marginal land that is not needed for food production and is of poor quality and subject to drought stress. Thus, here we define an ideotype for drought tolerance that will enable biomass production to be maintained in the face of moderate drought stress. This includes traits that can readily be measured in wide populations of several hundred unique genotypes for genome-wide association studies, alongside traits that are informative but can only easily be assessed in limited numbers or training populations that may be more suitable for genomic selection. Phenotyping, not genotyping, is now the major bottleneck for progress, since in all lignocellulosic crops studied extensive use has been made of next-generation sequencing such that several thousand markers are now available and populations are emerging that will enable rapid progress for drought-tolerance breeding. The emergence of novel technologies for targeted genotyping by sequencing are particularly welcome. Genome editing has already been demonstrated for Populus and offers significant potential for rapid deployment of drought-tolerant crops through manipulation of ABA receptors, as demonstrated in Arabidopsis, with other gene targets yet to be tested. CONCLUSIONS: Bioenergy is predicted to be the fastest-developing renewable energy over the coming decade and significant investment over the past decade has been made in developing genomic resources and in collecting wild germplasm from within the natural ranges of several tree and grass crops. Harnessing these resources for climate-resilient crops for the future remains a challenge but one that is likely to be successful.
Asunto(s)
Sequías , Árboles , Clima , Productos Agrícolas , Estudio de Asociación del Genoma CompletoRESUMEN
Agriculture contributes 18% of India's greenhouse gas (GHG) emissions. Yet, little is known about the energy requirements of individual crops, making it difficult to link nutrition-enhancing dietary changes to energy consumption and climate change. We estimate the energy and CO2 intensity of food grains (rice, wheat, sorghum, maize, pearl millet and finger millet) taking into account their irrigation requirements, water source, dependence on groundwater, yields, fertilizer and machinery inputs. Rice is the most energy-intensive cereal, while millets are the least. Total energy use contributes 16% of GHG emissions for rice, due to its high methane emissions, and 56% for wheat. Fertilizer production and use dominates GHG emissions from all crops, contributing 52% of GHGs from cereals. Energy intensities vary by up to a factor of four across the country, due to varying water requirements, irrigation sources and groundwater table depths. The results suggest that replacing rice with other cereals has the potential to reduce energy consumption and GHGs, though the spatial variation of production shifts would influence the extent of this reduction and the possible trade-offs with total production.
Asunto(s)
Contaminantes Atmosféricos/análisis , Producción de Cultivos , Grano Comestible/crecimiento & desarrollo , Gases de Efecto Invernadero/análisis , Metano/análisis , Óxido Nitroso/análisis , Riego Agrícola , Fertilizantes/análisis , Agua Subterránea/análisis , IndiaRESUMEN
In temperate and boreal ecosystems, seasonal cycles of growth and dormancy allow perennial plants to adapt to winter conditions. We show, in hybrid aspen trees, that photoperiodic regulation of dormancy is mechanistically distinct from autumnal growth cessation. Dormancy sets in when symplastic intercellular communication through plasmodesmata is blocked by a process dependent on the phytohormone abscisic acid. The communication blockage prevents growth-promoting signals from accessing the meristem. Thus, precocious growth is disallowed during dormancy. The dormant period, which supports robust survival of the aspen tree in winter, is due to loss of access to growth-promoting signals.
Asunto(s)
Ácido Abscísico/fisiología , Comunicación Celular/fisiología , Fotoperiodo , Latencia en las Plantas/fisiología , Reguladores del Crecimiento de las Plantas/fisiología , Populus/crecimiento & desarrollo , Árboles/crecimiento & desarrollo , Ritmo Circadiano , Meristema/citología , Meristema/crecimiento & desarrollo , Populus/citología , Populus/genética , Estaciones del Año , Árboles/citología , Árboles/genéticaRESUMEN
We report the draft genome of the black cottonwood tree, Populus trichocarpa. Integration of shotgun sequence assembly with genetic mapping enabled chromosome-scale reconstruction of the genome. More than 45,000 putative protein-coding genes were identified. Analysis of the assembled genome revealed a whole-genome duplication event; about 8000 pairs of duplicated genes from that event survived in the Populus genome. A second, older duplication event is indistinguishably coincident with the divergence of the Populus and Arabidopsis lineages. Nucleotide substitution, tandem gene duplication, and gross chromosomal rearrangement appear to proceed substantially more slowly in Populus than in Arabidopsis. Populus has more protein-coding genes than Arabidopsis, ranging on average from 1.4 to 1.6 putative Populus homologs for each Arabidopsis gene. However, the relative frequency of protein domains in the two genomes is similar. Overrepresented exceptions in Populus include genes associated with lignocellulosic wall biosynthesis, meristem development, disease resistance, and metabolite transport.
Asunto(s)
Duplicación de Gen , Genoma de Planta , Populus/genética , Análisis de Secuencia de ADN , Arabidopsis/genética , Mapeo Cromosómico , Biología Computacional , Evolución Molecular , Etiquetas de Secuencia Expresada , Expresión Génica , Genes de Plantas , Análisis de Secuencia por Matrices de Oligonucleótidos , Filogenia , Proteínas de Plantas/química , Proteínas de Plantas/genética , Polimorfismo de Nucleótido Simple , Populus/crecimiento & desarrollo , Populus/metabolismo , Estructura Terciaria de Proteína , ARN de Planta/análisis , ARN no Traducido/análisisRESUMEN
Recent research has highlighted the importance of auxin concentration gradients during plant development. Establishment of these gradients is believed to involve polar auxin transport through specialized carrier proteins. We have used an experimental system, the wood-forming tissue of hybrid aspen, which allows tissue-specific expression analysis of auxin carrier genes and quantification of endogenous concentrations of the hormone. As part of this study, we isolated the putative polar auxin transport genes, PttLAX1-PttLAX3 and PttPIN1-PttPIN3, belonging to the AUX1-like family of influx and PIN1-like efflux carriers, respectively. Analysis of PttLAX and PttPIN expression suggests that specific positions in a concentration gradient of the hormone are associated with different stages of vascular cambium development and expression of specific members of the auxin transport gene families. We were also able demonstrate positive feedback of auxin on polar auxin transport genes. Entry into dormancy at the end of a growing season leads to a loss of auxin transport capacity, paralleled by reduced expression of PttLAX and PttPIN genes. Furthermore, data from field experiments show that production of the molecular components of the auxin transport machinery is governed by environmental controls. Our findings collectively demonstrate that trees have developed mechanisms to modulate auxin transport in the vascular meristem in response to developmental and environmental cues.
Asunto(s)
Ácidos Indolacéticos/metabolismo , Árboles/metabolismo , Secuencia de Bases , Transporte Biológico Activo/genética , Clonación Molecular , ADN de Plantas/genética , Ambiente , Expresión Génica , Genes de Plantas , Datos de Secuencia Molecular , Estaciones del Año , Árboles/genética , Árboles/crecimiento & desarrolloRESUMEN
Embryonal sarcoma of the liver is an unusual tumor. The cystic form is rare and can mimic hydatid disease. We present a case that was mistakenly treated as a hydatid cyst for 3 months. Surgery was successful in removing the mass.
Asunto(s)
Equinococosis Hepática/diagnóstico , Neoplasias Hepáticas/diagnóstico , Neoplasias de Células Germinales y Embrionarias/diagnóstico , Niño , Errores Diagnósticos , Humanos , Neoplasias Hepáticas/cirugía , Masculino , Neoplasias de Células Germinales y Embrionarias/cirugíaRESUMEN
The distribution and biosynthesis of indole-3-acetic acid (IAA) was investigated during early plant development in Arabidopsis. The youngest leaves analysed, less than 0.5 mm in length, contained 250 pg mg(-1) of IAA and also exhibited the highest relative capacity to synthesize this hormone. A decrease of nearly one hundred-fold in IAA content occurred as the young leaves expanded to their full size, and this was accompanied by a clear shift in both pool size and IAA synthesis capacity. The correlation between high IAA content and intense cell division was further verified in tobacco leaves, where a detailed analysis revealed that dividing mesophyll tissue contained ten-fold higher IAA levels than tissue growing solely by elongation. We demonstrated that all parts of the young Arabidopsis plant can potentially contribute to the auxin needed for growth and development, as not only young leaves, but also all other parts of the plant such as cotyledons, expanding leaves and root tissues have the capacity to synthesize IAA de novo. We also observed that naphthylphthalamic acid (NPA) treatment induced tissue-dependent feedback inhibition of IAA biosynthesis in expanding leaves and cotyledons, but intriguingly not in young leaves or in the root system. This observation supports the hypothesis that there is a sophisticated tissue-specific regulatory mechanism for auxin biosynthesis. Finally, a strict requirement for maintaining the pool sizes of IAA was revealed as reductions in leaf expansion followed both decreases and increases in the IAA levels in developing leaves. This indicates that leaves are not only important sources for IAA synthesis, but that normal leaf expansion depends on rigorous control of IAA homeostasis.
Asunto(s)
Arabidopsis/crecimiento & desarrollo , Ácidos Indolacéticos/metabolismo , Reguladores del Crecimiento de las Plantas/metabolismo , División Celular , Retroalimentación Fisiológica , Homeostasis , Mutación , Ftalimidas , Hojas de la Planta/citología , Brotes de la Planta , Nicotiana/crecimiento & desarrolloRESUMEN
The large vascular meristem of poplar trees with its highly organized secondary xylem enables the boundaries between different developmental zones to be easily distinguished. This property of wood-forming tissues allowed us to determine a unique tissue-specific transcript profile for a well defined developmental gradient. RNA was prepared from different developmental stages of xylogenesis for DNA microarray analysis by using a hybrid aspen unigene set consisting of 2,995 expressed sequence tags. The analysis revealed that the genes encoding lignin and cellulose biosynthetic enzymes, as well as a number of transcription factors and other potential regulators of xylogenesis, are under strict developmental stage-specific transcriptional regulation.
Asunto(s)
Árboles/crecimiento & desarrollo , Árboles/genética , Madera , Pared Celular/metabolismo , Celulosa/biosíntesis , Etiquetas de Secuencia Expresada , Perfilación de la Expresión Génica , Regulación del Desarrollo de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Lignina/biosíntesis , Meristema/genética , Meristema/crecimiento & desarrollo , Datos de Secuencia Molecular , Análisis de Secuencia por Matrices de Oligonucleótidos , Transcripción Genética , Árboles/metabolismoRESUMEN
Lateral root development in Arabidopsis provides a model for the study of hormonal signals that regulate postembryonic organogenesis in higher plants. Lateral roots originate from pairs of pericycle cells, in several cell files positioned opposite the xylem pole, that initiate a series of asymmetric, transverse divisions. The auxin transport inhibitor N-1-naphthylphthalamic acid (NPA) arrests lateral root development by blocking the first transverse division(s). We investigated the basis of NPA action by using a cell-specific reporter to demonstrate that xylem pole pericycle cells retain their identity in the presence of the auxin transport inhibitor. However, NPA causes indoleacetic acid (IAA) to accumulate in the root apex while reducing levels in basal tissues critical for lateral root initiation. This pattern of IAA redistribution is consistent with NPA blocking basipetal IAA movement from the root tip. Characterization of lateral root development in the shoot meristemless1 mutant demonstrates that root basipetal and leaf acropetal auxin transport activities are required during the initiation and emergence phases, respectively, of lateral root development.
Asunto(s)
Arabidopsis/crecimiento & desarrollo , Ácidos Indolacéticos/metabolismo , Raíces de Plantas/crecimiento & desarrollo , Arabidopsis/metabolismo , Arabidopsis/fisiología , Transporte Biológico , Diferenciación Celular , División Celular , Polaridad Celular , Ácidos Indolacéticos/antagonistas & inhibidores , Ácidos Indolacéticos/fisiología , Meristema/anatomía & histología , Meristema/crecimiento & desarrollo , Meristema/metabolismo , Ftalimidas/farmacología , Raíces de Plantas/anatomía & histología , Raíces de Plantas/metabolismo , Transducción de SeñalRESUMEN
Genetic screens have been performed to identify mutants with altered auxin homeostasis in Arabidopsis. A tagged allele of the auxin-overproducing mutant sur2 was identified within a transposon mutagenized population. The SUR2 gene was cloned and shown to encode the CYP83B1 protein, which belongs to the large family of the P450-dependent monooxygenases. SUR2 expression is up-regulated in sur1 mutants and induced by exogenous auxin in the wild type. Analysis of indole-3-acetic acid (IAA) synthesis and metabolism in sur2 plants indicates that the mutation causes a conditional increase in the pool size of IAA through up-regulation of IAA synthesis.
Asunto(s)
Arabidopsis/enzimología , Sistema Enzimático del Citocromo P-450/metabolismo , Ácidos Indolacéticos/metabolismo , Oxigenasas de Función Mixta/metabolismo , Alelos , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis , Sistema Enzimático del Citocromo P-450/genética , ADN de Plantas/aislamiento & purificación , Regulación de la Expresión Génica , Genes de Plantas , Homeostasis , Concentración de Iones de Hidrógeno , Indoles/metabolismo , Oxigenasas de Función Mixta/genética , Mutagénesis Insercional , Fenotipo , Raíces de Plantas , Reacción en Cadena de la Polimerasa/métodos , Semillas/metabolismoRESUMEN
cDNAs encoding cyclin H homologs were isolated from poplar (Populus tremula X tremuloides) and rice (Oryza sativa) plants, and were designated Pt;cycH;1 and Os;cycH;1, respectively. The deduced amino-acid sequences showed 40-60% similarity to human cyclin H and Schizosaccharomyces pombe Mcs2, with higher similarity in the cyclin box region. While Pt;cycH;1 and Os;cycH;1 were expressed in all tissues examined, the transcripts accumulated abundantly in dividing cells. Expression of Os;cycH;1 was abundant in the S-phase in partially synchronized suspension cells, and was induced by submergence in internodes of deepwater rice. A yeast two-hybrid assay demonstrated that both Pt;CycH;1 and Os;CycH;1 were able to interact with rice R2 kinase, which is structurally and functionally similar to cyclin-dependent kinase (CDK)-activating kinase (CAK) of vertebrates. Moreover, an in vitro pull-down assay showed that Os;CycH;1 specifically bound to R2 but not to other rice CDKs. When R2 was expressed in budding yeast CAK mutant, the suppression activity in terms of temperature-sensitivity was enhanced by co-expression with Os;cycH;1. Furthermore, in vitro kinase assay indicated that the kinase activities of R2 on CDKs and the carboxy-terminal domain (CTD) of the largest subunit of RNA polymerase II were markedly elevated by binding to Os;CycH;1. Our results suggest that cyclin H is a regulatory subunit of CAK, which positively controls CDK- and CTD-kinase activities in plant cells.
Asunto(s)
Quinasas CDC2-CDC28 , Ciclo Celular , Ciclinas/genética , Ciclinas/metabolismo , Oryza/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Árboles/metabolismo , Secuencia de Aminoácidos , Animales , Clonación Molecular , Quinasa 2 Dependiente de la Ciclina , Quinasas Ciclina-Dependientes/genética , Quinasas Ciclina-Dependientes/metabolismo , Ciclinas/química , Activación Enzimática , Humanos , Datos de Secuencia Molecular , Oryza/citología , Oryza/genética , Filogenia , Proteínas Serina-Treonina Quinasas/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Saccharomyces cerevisiae , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Árboles/citología , Árboles/genética , Quinasa Activadora de Quinasas Ciclina-DependientesRESUMEN
Yeast Snf4 is a prototype of activating gamma-subunits of conserved Snf1/AMPK-related protein kinases (SnRKs) controlling glucose and stress signaling in eukaryotes. The catalytic subunits of Arabidopsis SnRKs, AKIN10 and AKIN11, interact with Snf4 and suppress the snf1 and snf4 mutations in yeast. By expression of an Arabidopsis cDNA library in yeast, heterologous multicopy snf4 suppressors were isolated. In addition to AKIN10 and AKIN11, the deficiency of yeast snf4 mutant to grown on non-fermentable carbon source was suppressed by Arabidopsis Myb30, CAAT-binding factor Hap3b, casein kinase I, zinc-finger factors AZF2 and ZAT10, as well as orthologs of hexose/UDP-hexose transporters, calmodulin, SMC1-cohesin and Snf4. Here we describe the characterization of AtSNF4, a functional Arabidopsis Snf4 ortholog, that interacts with yeast Snf1 and specifically binds to the C-terminal regulatory domain of Arabidopsis SnRKs AKIN10 and AKIN11.
Asunto(s)
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Factor de Unión a CCAAT/genética , Proteínas Portadoras , Genes Supresores , Proteínas Quinasas/genética , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Factores de Transcripción/genética , Proteínas Quinasas Activadas por AMP , Secuencia de Aminoácidos , Proteínas de Arabidopsis/química , Secuencia de Bases , Factor de Unión a CCAAT/química , Cartilla de ADN , ADN Complementario , Datos de Secuencia Molecular , Proteínas Quinasas/química , Homología de Secuencia de Aminoácido , Factores de Transcripción/químicaRESUMEN
Mutation of the PRL1 gene, encoding a regulatory WD protein, results in glucose hypersensitivity and derepression of glucose-regulated genes in Arabidopsis. The yeast SNF1 protein kinase, a key regulator of glucose signaling, and Arabidopsis SNF1 homologs AKIN10 and AKIN11, which can complement the Deltasnf1 mutation, were found to interact with an N-terminal domain of the PRL1 protein in the two-hybrid system and in vitro. AKIN10 and AKIN11 suppress the yeast Deltasnf4 mutation and interact with the SNF4p-activating subunit of SNF1. PRL1 and SNF4 bind independently to adjacent C-terminal domains of AKIN10 and AKIN11, and these protein interactions are negatively regulated by glucose in yeast. AKIN10 and AKIN11, purified in fusion with glutathione S-transferase, undergo autophosphorylation and phosphorylate a peptide of sucrose phosphate synthase in vitro. The sucrose phosphate synthase-peptide kinase activity of AKIN complexes detected by immunoprecipitation is stimulated by sucrose in light-grown Arabidopsis plants. In comparison with wild type, the activation level of AKIN immunocomplexes is higher in the prl1 mutant, suggesting that PRL1 is a negative regulator of Arabidopsis SNF1 homologs. This conclusion is supported by the observation that PRL1 is an inhibitor of AKIN10 and AKIN11 in vitro.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis/genética , Proteínas Portadoras/genética , Regulación de la Expresión Génica de las Plantas , Péptidos y Proteínas de Señalización Intracelular , Proteínas Nucleares/genética , Proteínas de Plantas/genética , Proteínas Serina-Treonina Quinasas/genética , Secuencia de Aminoácidos , Arabidopsis/metabolismo , Proteínas Portadoras/metabolismo , Genes Fúngicos , Genes de Plantas , Datos de Secuencia Molecular , Mutación , Proteínas Nucleares/metabolismo , Proteínas de Plantas/metabolismo , Unión Proteica , Proteínas Serina-Treonina Quinasas/metabolismo , Alineación de SecuenciaRESUMEN
Molecular analysis of Arabidopsis mutants displaying hypocotyl elongation defects in both the dark and light revealed recently that steroids play an essential role as hormones in plants. Deficiencies in brassinosteroid biosynthesis and signalling permit photomorphogenic development and light-regulated gene expression in the dark, and result in severe dwarfism, male sterility and de-repression of stress-induced genes in the light. A cytochrome P450 steroid hydroxylase (CYP90) controls a rate limiting step in brassinosteroid biosynthesis and appears to function as a signalling factor in stress responses. Another key step in steroid biosynthesis is controlled by the Arabidopsis SNF1 kinases that phosphorylate the 3-hydroxy-3methylglutaryl-CoA reductase. The activity of SNF1 kinases is regulated by PRL1, an evolutionarily conserved alpha-importin-binding nuclear WD-protein. The prl1 mutation results in cell elongation defects, de-repression of numerous stress-induced genes, and augments the sensitivity of plants to glucose, cold stress and several hormones, including cytokinin, ethylene, auxin, and abscisic acid.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis/citología , Arabidopsis/metabolismo , Péptidos y Proteínas de Señalización Intracelular , Arabidopsis/efectos de la radiación , Carbono/metabolismo , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Tamaño de la Célula/efectos de los fármacos , Tamaño de la Célula/efectos de la radiación , Sistema Enzimático del Citocromo P-450/metabolismo , Genes de Plantas , Luz , Modelos Biológicos , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Transducción de Señal , Esteroide Hidroxilasas/metabolismo , Esteroides/metabolismoRESUMEN
A rapidly growing area of genome research is the generation of expressed sequence tags (ESTs) in which large numbers of randomly selected cDNA clones are partially sequenced. The collection of ESTs reflects the level and complexity of gene expression in the sampled tissue. To date, the majority of plant ESTs are from nonwoody plants such as Arabidopsis, Brassica, maize, and rice. Here, we present a large-scale production of ESTs from the wood-forming tissues of two poplars, Populus tremula L. x tremuloides Michx. and Populus trichocarpa 'Trichobel.' The 5,692 ESTs analyzed represented a total of 3,719 unique transcripts for the two cDNA libraries. Putative functions could be assigned to 2,245 of these transcripts that corresponded to 820 protein functions. Of specific interest to forest biotechnology are the 4% of ESTs involved in various processes of cell wall formation, such as lignin and cellulose synthesis, 5% similar to developmental regulators and members of known signal transduction pathways, and 2% involved in hormone biosynthesis. An additional 12% of the ESTs showed no significant similarity to any other DNA or protein sequences in existing databases. The absence of these sequences from public databases may indicate a specific role for these proteins in wood formation. The cDNA libraries and the accompanying database are valuable resources for forest research directed toward understanding the genetic control of wood formation and future endeavors to modify wood and fiber properties for industrial use.
Asunto(s)
Etiquetas de Secuencia Expresada , Genes de Plantas , Árboles/genética , Arabidopsis/genética , Brassica/genética , Clonación Molecular , Cruzamientos Genéticos , ADN Complementario , Enzimas/genética , Expresión Génica , Biblioteca de Genes , Datos de Secuencia Molecular , Oryza/genética , Proteínas de Plantas/genética , Árboles/anatomía & histología , Árboles/citología , Zea mays/genéticaRESUMEN
The prl1 mutation localized by T-DNA tagging on Arabidopsis chromosome 4-44 confers hypersensitivity to glucose and sucrose. The prl1 mutation results in transcriptional derepression of glucose responsive genes defining a novel suppressor function in glucose signaling. The prl1 mutation also augments the sensitivity of plants to growth hormones including cytokinin, ethylene, abscisic acid, and auxin; stimulates the accumulation of sugars and starch in leaves; and inhibits root elongation. PRL1 encodes a regulatory WD protein that interacts with ATHKAP2, an alpha-importin nuclear import receptor, and is imported into the nucleus in Arabidopsis. Potential functional conservation of PRL1 homologs found in other eukaryotes is indicated by nuclear localization of PRL1 in monkey COS-1 cells and selective interaction of PRL1 with a nuclear protein kinase C-betaII isoenzyme involved in human insulin signaling.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis/genética , Proteínas Portadoras/fisiología , Glucosa/fisiología , Péptidos y Proteínas de Señalización Intracelular , Proteínas Nucleares/fisiología , Reguladores del Crecimiento de las Plantas/fisiología , Proteínas de Plantas , Secuencia de Aminoácidos , Arabidopsis/fisiología , Proteínas Portadoras/genética , Citocininas/fisiología , Regulación de la Expresión Génica de las Plantas , Humanos , Isoenzimas/metabolismo , Carioferinas , Datos de Secuencia Molecular , Mutación , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Proteína Quinasa C/metabolismo , Proteína Quinasa C beta , Semillas/crecimiento & desarrollo , Semillas/metabolismo , Alineación de SecuenciaRESUMEN
The metabolism of indole-3-acetic acid (IAA) was investigated in 14-d-old Arabidopsis plants grown in liquid culture. After ruling out metabolites formed as an effect of nonsterile conditions, high-level feeding, and spontaneous interconversions, a simple metabolic pattern emerged. Oxindole-3-acetic acid (OxIAA), OxIAA conjugated to a hexose moiety via the carboxyl group, and the conjugates indole-3-acetyl aspartic acid (IAAsp) and indole-3-acetyl glutamate (IAGlu) were identified by mass spectrometry as primary products of IAA fed to the plants. Refeeding experiments demonstrated that none of these conjugates could be hydrolyzed back to IAA to any measurable extent at this developmental stage. IAAsp was further oxidized, especially when high levels of IAA were fed into the system, yielding OxIAAsp and OH-IAAsp. This contrasted with the metabolic fate of IAGlu, since that conjugate was not further metabolized. At IAA concentrations below 0.5 microM, most of the supplied IAA was metabolized via the OxIAA pathway, whereas only a minor portion was conjugated. However, increasing the IAA concentrations to 5 microM drastically altered the metabolic pattern, with marked induction of conjugation to IAAsp and IAGlu. This investigation used concentrations for feeding experiments that were near endogenous levels, showing that the metabolic pathways controlling the IAA pool size in Arabidopsis are limited and, therefore, make good targets for mutant screens provided that precautions are taken to avoid inducing artificial metabolism.