Ammonium and nitric oxide condition the establishment of Arabidopsis Ler/Kas-2 immune-related hybrid incompatibility.

MAIN CONCLUSION: High ammonium suppresses hybrid incompatibility between Ler and Kas-2 accessions through lowering nitric oxide levels and nitrate reductase activity required for autoimmunity. The immune-related hybrid incompatibility (HI) between Landsberg erecta (Ler) and Kashmir-2 (Kas-2) accessions is due to a deleterious genetic interaction between the RPP1 (RECOGNITION OF PERONOSPORA PARASITICA1)-like Ler locus and Kas-2 alleles of the receptor-like kinase SRF3 (STRUBBELIG RECEPTOR FAMILY 3). The genetic incompatibility is temperature-dependent and leads to constitutive activation of the salicylic acid (SA) pathway, dwarfism and cell death at 14-16 °C. Here we investigated the effect of nutrition on the occurrence of Ler/Kas-2 HI and found that high ammonium suppresses Ler/Kas-2 incompatible phenotypes independently of the ammonium/nitrate ratio. Ammonium feeding leads to compromised disease resistance to Pseudomonas syringae pv. tomato DC3000, lower total SA, nitric oxide and nitrate reductase activity in Ler/Kas-2 incompatible hybrids. In addition, we find that Ler/Kas-2 incompatibility is dependent on NPR1 (NONEXPRESSER OF PR GENES 1) and nitric oxide production. Overall, this work highlights the effect of nutrition on the expression of incompatible phenotypes independently of temperature.

RGS14414 treatment induces memory enhancement and rescues episodic memory deficits.

Memory deficits affect a large proportion of the human population and are associated with aging and many neurologic, neurodegenerative, and psychiatric diseases. Treatment of this mental disorder has been disappointing because all potential candidates studied thus far have failed to produce consistent effects across various types of memory and have shown limited to no effects on memory deficits. Here, we show that the promotion of neuronal arborization through the expression of the regulator of G-protein signaling 14 of 414 amino acids (RGS14414) not only induced robust enhancement of multiple types of memory but was also sufficient for the recovery of recognition, spatial, and temporal memory, which are kinds of episodic memory that are primarily affected in patients or individuals with memory dysfunction. We observed that a surge in neuronal arborization was mediated by up-regulation of brain-derived neurotrophic factor (BDNF) signaling and that the deletion of BDNF abrogated both neuronal arborization activation and memory enhancement. The activation of BDNF-dependent neuronal arborization generated almost 2-fold increases in synapse numbers in dendrites of pyramidal neurons and in neurites of nonpyramidal neurons. This increase in synaptic connections might have evoked reorganization within neuronal circuits and eventually supported an increase in the activity of such circuits. Thus, in addition to showing the potential of RGS14414 for rescuing memory deficits, our results suggest that a boost in circuit activity could facilitate memory enhancement and the reversal of memory deficits.-Masmudi-Martín, M., Navarro-Lobato, I., López-Aranda, M. F., Delgado, G., Martín-Montañez, E., Quiros-Ortega, M. E., Carretero-Rey, M., Narváez, L., Garcia-Garrido, M. F., Posadas, S., López-Téllez, J. F., Blanco, E., Jiménez-Recuerda, I., Granados-Durán, P., Paez-Rueda, J., López, J. C., Khan, Z. U. RGS14414 treatment induces memory enhancement and rescues episodic memory deficits.

Optimización de la conservación in vitro de germoplasma de Dioscorea spp por crecimiento mínimo / Optimization of in vitro conservation of Dioscorea spp germplasm by minimal growth

El ñame Criollo (Dioscorea alata) y el ñame Espino (Dioscorea rotundata) se constituyen como las dos especies mayormente cultivadas en el departamento de Sucre, Colombia. Por esta razón en la Universidad de Sucre se han implementado técnicas para lograr su conservación mediante la propagación in vitro, sin embargo esta metodología conserva las accesiones por un periodo no mayor a los 4 meses, provocando continuos subcultivos, aumento de costos y mano de obra. Por ello la presente investigación tuvo como objetivo establecer medios de cultivo óptimos para la conservación in vitro por crecimiento mínimo de diferentes accesiones (D. alata y D. rotundata) pertenecientes al banco de germoplasma de la Universidad de Sucre, durante un periodo de 8 meses. Esto mediante la modificación del medio de cultivo base MS; con los siguientes osmolitos: sacarosa, manitol y sorbitol. Se avaluaron 8 tratamientos (T) en los siguientes porcentajes T1 (control) (3:0:0), T2 (0:1,5:0), T3 (0:0:2), T4 (0:1,5:2), T5 (0:0:1) y T6 (0:0:3), T7 (0:1,5:1) y T8 (0:1,5:3). Cada 30 días se evaluó: supervivencia (%), hojas expandidas (%), longitud del tallo y raíz, número de nudos y raíces, oxidación (%), senescencia foliar (%) y callo (%). Los resultados mostraron que las especies D. alata y D. rotundata, se conservan de forma óptima, en la combinación T4 (0:1,5:2), donde se evidencia un alto porcentaje de supervivencia, un mínimo porcentaje de senescencia foliar y un desarrollo restringido en el resto de variables. Garantizando así la disponibilidad y el desarrollo normal de las accesiones en un periodo superior a 4 meses.

Dioscorea alata cv. "Criollo" and Dioscorea rotundata cv. "Espino" are constituted as the two cultivars mostly cultivated in the department of Sucre, Colombia. For this reason the University of Sucre has been implementing tissue culture techniques for their multiplication throughout in vitro propagation. However, this methodology support accessions for a period about 4 months, causing continuous subcultures, increased costs and labor. Therefore the objective of the present investigation was to establish an optimal culture media for in vitro minimal growth conservation of different accessions (D. alata and D. rotundata) from the University of Sucre yam´s genebank , for a period of 8 months by modifying the basic MS culture medium. The following osmolytes were used: sucrose, mannitol and sorbitol in different percentages (S:M:S). Eight treatments (T) in the following percentages were evaluated: T1 (control) (3:0:0), T2 (0:1,5:0), T3(0:0:2), T4 (0:1,5:2), T5 (0:0:1) y T6 (0:0:3), T7 (0:1,5:1) y T8 (0:1,5:3). Every 30 days data was recorded for: survival (%), expanded leaves (%), length of stem and roots, number of leaves and roots, phenolization (%), leaf senescence (%) and callus presence (%). The best results for D. alata and D. rotundata, were observed in treatment T4 (0:1,5:2), where a high percentage of survival evidence, a minimum percentage of leaf senescence and a limited response for the other variables. Therefore, these results indicate the potential of this media, to increase 100% in vitro growth conservation over the conventional media, and ensuring the viability and normal development of the accessions for more than four months period.