RESUMO
Plant scientists usually record several indicators in their abiotic factor experiments. The common statistical management involves univariate analyses. Such analyses generally create a split picture of the effects of experimental treatments since each indicator is addressed independently. The Euclidean distance combined with the information of the control treatment could have potential as an integrating indicator. The Euclidean distance has demonstrated its usefulness in many scientific fields but, as far as we know, it has not yet been employed for plant experimental analyses. To exemplify the use of the Euclidean distance in this field, we performed an experiment focused on the effects of mannitol on sugarcane micropropagation in temporary immersion bioreactors. Five mannitol concentrations were compared: 0, 50, 100, 150 and 200 mM. As dependent variables we recorded shoot multiplication rate, fresh weight, and levels of aldehydes, chlorophylls, carotenoids and phenolics. The statistical protocol which we then carried out integrated all dependent variables to easily identify the mannitol concentration that produced the most remarkable integral effect. Results provided by the Euclidean distance demonstrate a gradually increasing distance from the control in function of increasing mannitol concentrations. 200 mM mannitol caused the most significant alteration of sugarcane biochemistry and physiology under the experimental conditions described here. This treatment showed the longest statistically significant Euclidean distance to the control treatment (2.38). In contrast, 50 and 100 mM mannitol showed the lowest Euclidean distances (0.61 and 0.84, respectively) and thus poor integrated effects of mannitol. The analysis shown here indicates that the use of the Euclidean distance can contribute to establishing a more integrated evaluation of the contrasting mannitol treatments.
Assuntos
Reatores Biológicos , Manitol/farmacologia , Saccharum/crescimento & desenvolvimento , Manitol/administração & dosagem , Matemática , Meristema/efeitos dos fármacos , Meristema/crescimento & desenvolvimento , Saccharum/efeitos dos fármacosRESUMO
The Anaphase Promoting Complex (APC) controls CDK activity by targeting the ubiquitin-dependent proteolysis of S-phase and mitosis-promoting cyclins. Here, we report that the ectopic expression of the Arabidopsis CDC27a, an APC subunit, accelerates plant growth and results in plants with increased biomass production. CDC27a overexpression was associated to apical meristem restructuration, protoplasts with higher (3)H-thimidine incorporation and altered cell-cycle marker expression. Total protein extracts immunoprecipitated with a CDC27a antibody showed ubiquitin ligase activity, indicating that the Arabidopsis CDC27a gets incorporated into APC complexes. These results indicate a role of AtCDC27a in regulation of plant growth and raise the possibility that the activity of the APC and the rates of plant cell division could be regulated by the concentration of the CDC27a subunit.
Assuntos
Proteínas de Arabidopsis/genética , Proteínas de Ciclo Celular/genética , Regulação da Expressão Gênica de Plantas , Nicotiana/genética , Plantas Geneticamente Modificadas/genética , Proteínas de Arabidopsis/metabolismo , Western Blotting , Proteínas de Ciclo Celular/metabolismo , Divisão Celular , Linhagem Celular , Tamanho Celular , Flores/genética , Flores/crescimento & desenvolvimento , Flores/metabolismo , Perfilação da Expressão Gênica , Imunoprecipitação , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/metabolismo , Protoplastos/citologia , Protoplastos/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Timidina/metabolismo , Nicotiana/citologia , Nicotiana/metabolismo , Trítio/metabolismo , UbiquitinaçãoRESUMO
Sister-chromatid separation and exit from mitosis require ubiquitin-mediated proteolysis of cell cycle regulators such as cyclin B and securin. The specificity of the reaction is controlled by an ubiquitin-ligase multiprotein complex known as APC (Anaphase Promoting Complex). Comparison of the coding sequences of Arabidopsis genes with the Genbank database reveals extensive homology of the predicted ORFs with the corresponding proteins of other eukaryotes, indicating that the APC is well conserved in plants. However, different from other eukaryotes, the Arabidopsis genes have some particular characteristics, such as the presence of two copies of the CDC27 gene. Furthermore, expression analyses of the AtAPC genes disclose complex profiles that differ, depending on the tissue examined. In actively dividing cell suspensions there is a direct correspondence between the rates of proliferation and mRNA levels from the AtAPC components. On the other hand, in plant organs, dark-grown seedlings and during leaf growth, this correlation is lost and the AtAPC genes are highly expressed in tissues with low overall cell division. Moreover, expression patterns diverge between the subunit genes, raising the possibility that there could be more than one form of the APC, which would execute distinct functions during plant development. The results suggest that an important layer of regulation of APC/C in plants could operate through subunit availability in specific tissues and/or cellular compartments.