RESUMEN
Resumen: La apropiada organogénesis de las plantas, durante su ciclo de vida, propicia su desarrollo y la adaptación a diferentes condiciones am bientales. Diversas fitohormonas regulan el desarrollo vegetal, pero la auxina denominada ácido indol-3-acético (AIA) es una de las más importantes. El AIA se sintetiza en la parte aérea de la planta y se moviliza a los tejidos demandantes por un transporte rápido que utiliza el floema y por el transporte polar de auxinas (TPA). Recientemente, se ha demostrado que las auxinas también se movilizan mediante el transporte simplástico (TS) a través de los plasmodesmos (PD), cuya apertura o cierre está regulada respectivamente por la degradación o la deposición de la callosa. El objetivo del presente trabajo fue profundizar en los avances sobre la participación del transporte simplástico de las auxinas durante el desarrollo vegetal, así como la degradación o deposición de la callosa, en el cierre o apertura de los PD, para regular el desarrollo de algunos órganos de Arabidopsis thaliana. La intervención de las proteínas PDLP5 es determinante para la deposición de la callosa en los PD, lo que regula la distribución de la auxina e impacta en la formación radicular, especialmente en las raíces laterales. La participación del TS es importante para desarrollar la actividad de las auxinas, lo cual favorece la formación radicular, necesaria en la mejora de absorción de nutrientes de las plantas. Este conocimiento puede ser utilizado para mejorar las plantas de interés agronómico.
Abstract: The appropriate organogenesis of plants during their life cycle promotes their development and adaptation to different environmental conditions. Various phytohormones regulate plant development but auxin, called Indole-3-Acetic Acid (IAA), is one of the most important. IAA is synthesized in the aerial part of plant and is mobilized to the demanding tissues by a rapid transport using the phloem and by the polar auxin transport (PAT). Recently, it has been shown that auxins also are mobilized by a symplastic transport (ST) through plasmodesmata (PD), which opening or closing is regulated by the callose degradation or deposition respectively. The objective of the present work was to deepen the analysis on the participation of symplastic transport of auxins during plant development, as well in the callose degradation or deposition, in the closing or opening of the PD, that regulates the development of some organs of Arabidopsis thaliana. The intervention of PDLP5 proteins is decisive for the callose deposition in the PD, which regulates the auxin distribution and impacts root formation, especially at the lateral roots. The participation of TS is important to develop the auxin activity, which favors root formation, necessary for the improvement plant nutrient absorption. This knowledge can be used to improve development plants of agronomic interest.
RESUMEN
Superoxide dismutase (SOD) activities of the oomycete Phytophthora cinnamomi were examined. Five polypeptides with manganese superoxide dismutase (MnSOD) activity were found in mycelium growing in liquid culture with relative molecular weights ranging from approximately 25 to 100 kDa. Comparison with characterized avocado SODs showed no evidence for the presence of either iron or copper/zinc SODs in P. cinnamomi. The level of activity of the MnSOD polypeptides decreased in the presence of avocado root or cell wall components. Growth of P. cinnamomi, measured as dry weight, increased when the mycelium was grown in the presence of superoxide anion (O(2) (-)), which was added exogenously. Our results suggest that the metabolism of O(2) (-) has an important role in the development of P. cinnamomi.
Asunto(s)
Proteínas Fúngicas/química , Micelio/enzimología , Phytophthora/enzimología , Superóxido Dismutasa/química , Pared Celular/química , Proteínas Fúngicas/antagonistas & inhibidores , Proteínas Fúngicas/metabolismo , Peróxido de Hidrógeno/química , Isoenzimas/antagonistas & inhibidores , Isoenzimas/química , Isoenzimas/metabolismo , Micelio/efectos de los fármacos , Micelio/crecimiento & desarrollo , Oxidantes/farmacología , Persea/microbiología , Phytophthora/efectos de los fármacos , Phytophthora/crecimiento & desarrollo , Raíces de Plantas/microbiología , Cianuro de Potasio/química , Superóxido Dismutasa/antagonistas & inhibidores , Superóxido Dismutasa/metabolismo , Superóxidos/farmacologíaRESUMEN
In the last decades, the incidence of type 2 diabetes has increased alarmingly worldwide including Mexico, and particularly among Mexican-Americans. The etiology of type 2 diabetes is multiple, in which there is a complex interaction between environmental and genetic risk factors. The kidney is a target organ that is damaged when type 2 diabetes occurs. The genetic predisposition for kidney disease in type 2 diabetes patients is the end result of the cumulative effects of multiple genetic and environmental factors. The components of the renin-angiotensin system and its genetic polymorphisms represent an area of intense research due to its association with kidney disease. Early identification of genetic risk factors for developing kidney disease could lead to timely treatment and may influence the response of the patients to drug therapy and diet recommendations.
Asunto(s)
Diabetes Mellitus Tipo 2/complicaciones , Nefropatías Diabéticas/etiología , Sistema Renina-Angiotensina/fisiología , Diabetes Mellitus Tipo 2/genética , Nefropatías Diabéticas/genética , Humanos , Peptidil-Dipeptidasa A/genética , Peptidil-Dipeptidasa A/fisiología , Sistema Renina-Angiotensina/genéticaRESUMEN
Auxin is known to stimulate protein synthesis in many plant tissues, but the mechanisms involved in this process are unknown. The present research inquires whether auxin might regulate selective translation of mRNAs by inducing S6 ribosomal protein phosphorylation on the 40S ribosomal subunit in maize (Zea mays L.). Maize embryonic axes auxin-stimulated by natural (IAA) or synthetic (Dicamba or 1-NAA) auxins, selectively increased ribosomal protein synthesis. This effect was not reproduced by auxin inactive analogue 2-NAA. Enhanced S6 ribosomal protein phosphorylation on the 40S ribosomal subunit was also observed after auxin stimulation, as measured by [32P] incorporation into this protein. This increment did not occur when stimulation was performed with the inactive auxin analogue. Further, increased recruitment into polysomes of two 5'TOP-like mRNAs, encoding for the initiation translation factor eIF-iso4E and the S6 ribosomal protein, was also found after auxin stimulation of maize axes. A positive correlation was established between the levels of S6 ribosomal protein phosphorylation and the S6 ribosomal protein transcript recruitment into polysomes by means of okadaic acid or heat shock application to maize axes. These data indicate that auxin stimulates S6 ribosomal protein phosphorylation on maize ribosomes, concomitant to the recruitment of specific mRNAs (5'TOP-like mRNAs) into polysomes for translation. It is proposed that by this mechanism auxin regulate the synthesis of specific proteins in maize tissues.