Phosphorylation Dynamics in a flg22-Induced, G Protein-Dependent Network Reveals the AtRGS1 Phosphatase.

The microbe-associated molecular pattern flg22 is recognized in a flagellin-sensitive 2-dependent manner in root tip cells. Here, we show a rapid and massive change in protein abundance and phosphorylation state of the Arabidopsis root cell proteome in WT and a mutant deficient in heterotrimeric G-protein-coupled signaling. flg22-induced changes fall on proteins comprising a subset of this proteome, the heterotrimeric G protein interactome, and on highly-populated hubs of the immunity network. Approximately 95% of the phosphorylation changes in the heterotrimeric G-protein interactome depend, at least partially, on a functional G protein complex. One member of this interactome is ATBα, a substrate-recognition subunit of a protein phosphatase 2A complex and an interactor to Arabidopsis thaliana Regulator of G Signaling 1 protein (AtRGS1), a flg22-phosphorylated, 7-transmembrane spanning modulator of the nucleotide-binding state of the core G-protein complex. A null mutation of ATBα strongly increases basal endocytosis of AtRGS1. AtRGS1 steady-state protein level is lower in the atbα mutant in a proteasome-dependent manner. We propose that phosphorylation-dependent endocytosis of AtRGS1 is part of the mechanism to degrade AtRGS1, thus sustaining activation of the heterotrimeric G protein complex required for the regulation of system dynamics in innate immunity. The PP2A(ATBα) complex is a critical regulator of this signaling pathway.

Single-cell proteomics differentiates Arabidopsis root cell types.

Single-cell proteomics (SCP) is an emerging approach to resolve cellular heterogeneity within complex tissues of multi-cellular organisms. Here, we demonstrate the feasibility of SCP on plant samples using the model plant Arabidopsis thaliana. Specifically, we focused on examining isolated single cells from the cortex and endodermis, which are two adjacent root cell types derived from a common stem cell lineage. From 756 root cells, we identified 3763 proteins and 1118 proteins/cell. Ultimately, we focus on 3217 proteins quantified following stringent filtering. Of these, we identified 596 proteins whose expression is enriched in either the cortex or endodermis and are able to differentiate these closely related plant cell types. Collectivity, this study demonstrates that SCP can resolve neighboring cell types with distinct functions, thereby facilitating the identification of biomarkers and candidate proteins to enable functional genomics.

Medicamentos genéricos ¿buenos y usables? La percepción de los estudiantes de medicina en un estado mexicano

Introducción: el conocimiento y la percepción hacia los medicamentos genéricos son temas que surgen como un factor importante a explorar en los estudiantes de medicina. Objetivo: determinar las diferencias entre los estudiantes de medicina de universidades públicas y privadas sobre la percepción y el uso de las Especialidades Farmacéuticas Genéricas (EFG). Materiales y métodos: se realizó un estudio cuantitativo de tipo observacional, transversal, analítico y comparativo en un universo de 858 estudiantes matriculados durante 2019-2020 en cinco escuelas de medicina del estado mexicano de Tabasco. A través de Google Forms se recolectaron los datos de un formulario auto aplicado con base a un cuestionario previamente validado. Se emplearon estadísticas descriptivas para evaluar las percepciones de los estudiantes y pruebas no paramétricas a través de un modelo de análisis de diferencia de medias para comparar el resultado entre las universidades. Resultados: la percepción de las dimensiones de calidad (8= 12,51) y eficacia (8=6,06) muestran una postura indecisa en general. En la fiabilidad (8=6,99), los alumnos estuvieron de acuerdo. Las dimensiones de preferencia-experiencia (8=10,649) y la de accesibilidad (X=7,01), colocan a los alumnos en el grupo de indecisos. En la comparación de medias de la escala de percepción de EFG (prueba t de estudent), la universidad pública presentó una media baja (8=24,72), mientras que en el grupo de universidades privadas fue mayor (8=26,06). En cuanto al uso de EFG, la universidad pública presentó una media 8=38,22, mientras que el grupo de universidades privadas fue menor (8=36,70). Conclusiones: se requiere incluir en los contenidos curriculares de los futuros profesionales de la medicina, mayor información sobre calidad, seguridad y eficacia de las EFG, lo que contribuirá a elevar el nivel de confianza en su prescripción.

Introduction: Knowledge and perception towards generic drugs are topics that emerge as an important factor to explore in medica students. Objective: To determine the differences between medical students from public and private universities on the perception and use of Generic Pharmaceutical Specialties (GFE). Materials and methods: A quantitative observational, cross-sectional, analytica and comparative study was conducted in a universe of 858 students enrolled during 2019-2020 in five medical schools in the Mexican state of Tabasco. Through Google Forms, data were collected from a self-applied form based on a previously validated questionnaire Descriptive statistics were used to assess student perceptions, and nonparametric tests through an analysis model for difference of means to compare the result between universities. Results: The perception of the dimensions of quality (8= 12,51) and efficacy (8=6,06) shows an indecisive position in general. On reliability (8=6,99), students agreed. The dimensions of preference-experience (8=10.649) and accessibility (8=7,01), place students in the group of undecideds. In the comparison of means of the GFE perception scale (student's t test), the public university presented a low mean (8=24,72), while in the group of private universities it was higher (8=26,06). Regarding the use of GFE, the public university presented a mean 8=38,22, while the group of private universities was lower (8=36,70). Conclusions: It is necessary to include in the curricular contents of future medical professionals more information on quality, safety and efficacy of GFE, which will contribute to raising the level of confidence in their prescription.

Production of phenolic metabolites by Deschampsia antarctica shoots using UV-B treatments during cultivation in a photobioreactor

Deschampsia antarctica (DA), the only species in the Gramineae family endemic to the Antarctic territory, is characterized by a combination of high levels of free endogenous phenylpropanoid compounds under normal in situ and in vitro growth conditions. In this article, we describe the design and use of a specific temporary immersion photobioreactor to produce both increased DA biomass and secondary metabolite accumulation by UV-B elicitation during cultivation. Three min-long immersions in an induction medium applied every 4 hrs at 14ºC +/- 1 and 20/4 hrs light/darkness photoperiod increased DA biomass production over previous in vitro reports. Biomass duplication was obtained at day 10.7 of culturing, and maximum total phenolics and antioxidant activity were observed after 14 day of culturing. The addition of UV-B radiation pulses for 0.5 hrs at 6 hrs intervals increased total phenolics and antioxidant activity more than 3- and 1.5- fold, respectively, compared to controls with no UV-B. Significant accumulation of scopoletin, chlorogenic acid, gallic acid and rutin was found in these plantlets. This is the first bioreactor designed to optimize biomass and phenylpropanoid production in DA.