High Auxin and High Phosphate Impact on RSL2 Expression and ROS-Homeostasis Linked to Root Hair Growth in Arabidopsis thaliana

Root hair size determines the surface area/volume ratio of the whole roots exposed to the nutrient and water pools, thereby likely impacting nutrient and water uptake rates. The speed at which they grow is determined both by cell-intrinsic factors like hormones (e.g., auxin) and external environmental signals like nutrient availability in the soil (e.g., phosphate). Overall root hair growth is controlled by the transcription factors RSL4 and RSL2. While high levels of auxin promote root hair growth, high levels of inorganic phosphate (Pi) in the media are able to strongly repress RSL4 and RSL2 expression linked to a decreased polar growth. In this work, we inquired the mechanism used by root hairs to integrate conflicting growth signals like the repressive signal of high Pi levels and a concomitant high auxin exposure that promotes growth and questioned whether these complex signals might activate known molecular players in root hair polar growth. Under these conditions, RSL2 expression (but not RSL4) is activated linked to ROS production and root hair growth. On the other hand, by blocking ROS production derived from the NADPH Oxidase C (or RBOHC for RESPIRATORY BURST OXIDASE HOMOLOG C) and ROS production from Secreted type-III Peroxidases (PERs), it was possible to repress the auxin growth-promoting effect. This study identifies a new layer of complexity between auxin, Pi nutrient availability and RSL2/RSL4 transcription factors all acting on ROS homeostasis and growth at the root hair level

Delayed Corneal Epithelial Healing after Intravitreal Bevacizumab: A Clinical and Experimental Study

Purpose: To report corneal epithelial defects (CEDs) and delayed epithelial healing after intravitreal bevacizumab (IVB) injection and to describe delayed corneal epithelial healing with topical administration of bevacizumab in an experimental rabbit model. Methods: A retrospective chart review was performed on 850 eyes of 850 patients with neovascular eye disease and diabetic macular edema who had received 1.25 to 2.5 mg IVB. In the experimental arm of the study, photorefractive keratectomy was used to create a 3 mm CED in the right eyes of 18 New Zealand rabbits which were then randomized to three equal groups. All rabbits received topical antibiotics, additionally those in group A received topical bevacizumab and animals in group B were treated with topical corticosteroids. The rate of epithelial healing was assessed at different time points using slitlamp photography. Results: In the clinical study, seven eyes of seven subjects developed CEDs the day after IVB injection. All of these eyes had preexisting corneal edema. The healing period ranged from 3 to 38 days (average 11 days) despite appropriate medical management. In the experimental study, topical bevacizumab and corticosteroids both significantly hindered corneal epithelial healing at 12 and 24 hours. Conclusion: Bevacizumab was demonstrated to cause CEDs in clinical settings. Moreover, corneal epithelial healing was delayed by topical application of bevacizumab, in the experimental model. These short-term results suggest that corneal edema may be considered as a risk factor for epithelial defects after IVB

Social perception on Science and Technology in the northeastern provinces of Argentina.

Se presentan datos de la percepción social  de  la  Ciencia  y  la  Tecnología  de  los habitantes  de  la  región  nordeste  de  Argentina  que  reflejan  una  sociedad  con moderada  cultura  científica  y  tecnológica. La  cuestión  "que  imagen  tiene  de  la  ciencia"   se  utilizó  para  realizar  una valoración general donde más de la mitad de  los  encuestados  tuvo  una  opinión positiva.  Sin  embargo,  solo  el  14%  de  la muestra  considera  que  la  Ciencia  y  la Tecnología  mejoran  la  calidad  de  la  vida  humana.  Se  propone  la  generación  de cultura  científica  a  través  de  la  participación  de  los  actores  sociales involucrados,  estimulados  por  los  organismos  públicos  responsables  del desarrollo  científico  y  tecnológico.  Los  resultados  pueden  ser  utilizados  para  la toma  de  decisiones  bien informadas en  el  desenvolvimiento  social  y  la  participación ciudadana;  además,  para  orientar  la  política científica y tecnológica.This paper presents data related to the social perception of science and technology to the people of the northeast of Argentina of the country that reflect a society with moderate scientific and technological culture. The question "what image has of science" was used to make a general assessment where more than half of surveyed had a positive opinion. However, only 14% of the sample believes that science and technology improve the quality of human life.We propose the generation of scientific culture through the participation of the social actors involved, stimulated by public agencies responsible for the scientific and technological development. The results can be used for making informed decisions in the social development and citizen participation, in addition to guide scientific and technological policy.Fil: Juarez, Rolando Pablo. Universidad Nacional del Nordeste. Facultad de Odontologia. Secretaria de Investigacion. Gabinete de Inv.interd.de Prevencion Salud y Epidemologia; Argentina;Fil: Martinez, Sandra Edda. Universidad Nacional del Nordeste. Facultad de Odontologia. Departamento de Clinicas Integradas;Fil: Dho, María Silvina. Universidad Nacional del Nordeste. Facultad de Odontologia. Secretaria de Investigacion. Gabinete de Inv.interd.de Prevencion Salud y Epidemologia;Fil: Vaculik, Patricia. Universidad Nacional del Nordeste. Facultad de Odontologia. Secretaria de Investigacion. Gabinete de Inv.interd.de Prevencion Salud y Epidemologia;Fil: Llarens, Adriana N.. Universidad Nacional del Nordeste. Facultad de Odontologia. Secretaria de Investigacion. Gabinete de Inv.interd.de Prevencion Salud y Epidemologia;Fil: Cúndom, Juan M.. Universidad Nacional del Nordeste. Facultad de Odontologia. Secretaria de Investigacion. Gabinete de Inv.interd.de Prevencion Salud y Epidemologia;Fil: Almirón, María. Universidad Nacional del Nordeste. Facultad de Odontologia. Secretaria de Investigacion. Gabinete de Inv.interd.de Prevencion Salud y Epidemologia

Complex regulation of prolyl-4-hydroxylases impacts root hair expansion.

Root hairs are single cells that develop by tip growth, a process shared with pollen tubes, axons, and fungal hyphae. However, structural plant cell walls impose constraints to accomplish tip growth. In addition to polysaccharides, plant cell walls are composed of hydroxyproline-rich glycoproteins (HRGPs), which include several groups of O-glycoproteins, including extensins (EXTs). Proline hydroxylation, an early post-translational modification (PTM) of HRGPs catalyzed by prolyl 4-hydroxylases (P4Hs), defines their subsequent O-glycosylation sites. In this work, our genetic analyses prove that P4H5, and to a lesser extent P4H2 and P4H13, are pivotal for root hair tip growth. Second, we demonstrate that P4H5 has in vitro preferred specificity for EXT substrates rather than for other HRGPs. Third, by P4H promoter and protein swapping approaches, we show that P4H2 and P4H13 have interchangeable functions but cannot replace P4H5. These three P4Hs are shown to be targeted to the secretory pathway, where P4H5 forms dimers with P4H2 and P4H13. Finally, we explore the impact of deficient proline hydroxylation on the cell wall architecture. Taken together, our results support a model in which correct peptidyl-proline hydroxylation on EXTs, and possibly in other HRGPs, is required for proper cell wall self-assembly and hence root hair elongation in Arabidopsis thaliana

Complex regulation of prolyl-4-hydroxylases impacts root hair expansion.

Root hairs are single cells that develop by tip growth, a process shared with pollen tubes, axons, and fungal hyphae. However, structural plant cell walls impose constraints to accomplish tip growth. In addition to polysaccharides, plant cell walls are composed of hydroxyproline-rich glycoproteins (HRGPs), which include several groups of O-glycoproteins, including extensins (EXTs). Proline hydroxylation, an early post-translational modification (PTM) of HRGPs catalyzed by prolyl 4-hydroxylases (P4Hs), defines their subsequent O-glycosylation sites. In this work, our genetic analyses prove that P4H5, and to a lesser extent P4H2 and P4H13, are pivotal for root hair tip growth. Second, we demonstrate that P4H5 has in vitro preferred specificity for EXT substrates rather than for other HRGPs. Third, by P4H promoter and protein swapping approaches, we show that P4H2 and P4H13 have interchangeable functions but cannot replace P4H5. These three P4Hs are shown to be targeted to the secretory pathway, where P4H5 forms dimers with P4H2 and P4H13. Finally, we explore the impact of deficient proline hydroxylation on the cell wall architecture. Taken together, our results support a model in which correct peptidyl-proline hydroxylation on EXTs, and possibly in other HRGPs, is required for proper cell wall self-assembly and hence root hair elongation in Arabidopsis thaliana