Fundación Instituto Leloir

About: Fundación Instituto Leloir is a facility organization based out in Buenos Aires, Argentina. It is known for research contribution in the topics: Dentate gyrus & Neurogenesis. The organization has 702 authors who have published 1052 publications receiving 39299 citations.

Cellulose-rich secondary walls in wave-swept red macroalgae fortify flexible tissues.

Abstract: Cellulosic secondary walls evolved convergently in coralline red macroalgae, reinforcing tissues against wave-induced breakage, despite differences in cellulose abundance, microfibril orientation, and wall structure. Cellulose-enriched secondary cell walls are the hallmark of woody vascular plants, which develop thickened walls to support upright growth and resist toppling in terrestrial environments. Here we investigate the striking presence and convergent evolution of cellulosic secondary walls in coralline red algae, which reinforce thalli against forces applied by crashing waves. Despite ostensible similarities to secondary wall synthesis in land plants, we note several structural and mechanical differences. In coralline red algae, secondary walls contain three-times more cellulose (~ 22% w/w) than primary walls (~ 8% w/w), and their presence nearly doubles the total thickness of cell walls (~ 1.2 µm thick). Field emission scanning electron microscopy revealed that cellulose bundles are cylindrical and lack any predominant orientation in both primary and secondary walls. His-tagged recombinant carbohydrate-binding module differentiated crystalline and amorphous cellulose in planta, noting elevated levels of crystalline cellulose in secondary walls. With the addition of secondary cell walls, Calliarthron genicular tissues become significantly stronger and tougher, yet remain remarkably extensible, more than doubling in length before breaking under tension. Thus, the development of secondary walls contributes to the strong-yet-flexible genicular tissues that enable coralline red algae to survive along wave-battered coastlines throughout the NE Pacific. This study provides an important evolutionary perspective on the development and biomechanical significance of secondary cell walls in a non-model, non-vascular plant.

Estimación del area de las hojas en plantas de trigo bajo diferentes tipos de estrés abiótico

Abstract: En trigo, es posible estimar el area de las hojas (AF) utilizando el producto del largo, el ancho de la lamina (LxA) y un coeficiente de proporcionalidad (bm). Sin embargo, no hay informacion sobre la posibilidad de usar el mismo valor del coeficiente para estimar el area en plantas que sufren estres hidrico, luminico o nutricional. Para estudiar este punto se realizaron dos experimentos en los cuales se aplico sequia, sombreo y deficiencias de N y P a plantas de trigo.El coeficiente bm se calculo a partir de la regresion lineal entre AF y LxA y fue similar entre las plantas control y aquellas que sufrieron sequia o deficiencias de N o P, pero fue distinto en plantas sombreadas. El mayor valor de bm en las plantas sombreadas se debio a una mayor proporcion del sector medio de la lamina, definido por su forma rectangular. La validacion de la posibilidad de usar el bm del control para estimar AF en plantas estresadas se realizo por regresion lineal entre el AF medida y calculada. Se concluye que puede usarse el mismo coeficiente bm para estimar el AF en plantas no estresadas y en plantas que sufren sequia o deficiencias de N o P. El uso del mismo valor del coeficiente bm en plantas sombreadas llevo a una subestimacion del AF, la que fue mas pronunciada a medida que aumento el sombreo.

Hidden Structural Codes in Protein Intrinsic Disorder

Abstract: Intrinsic disorder is a major structural category in biology, accounting for more than 30% of coding regions across the domains of life, yet consists of conformational ensembles in equilibrium, a major challenge in protein chemistry. Anciently evolved papillomavirus genomes constitute an unparalleled case for sequence to structure–function correlation in cases in which there are no folded structures. E7, the major transforming oncoprotein of human papillomaviruses, is a paradigmatic example among the intrinsically disordered proteins. Analysis of a large number of sequences of the same viral protein allowed for the identification of a handful of residues with absolute conservation, scattered along the sequence of its N-terminal intrinsically disordered domain, which intriguingly are mostly leucine residues. Mutation of these led to a pronounced increase in both α-helix and β-sheet structural content, reflected by drastic effects on equilibrium propensities and oligomerization kinetics, and uncovers the ex...

Acidic pH triggers the phosphorylation of the response regulator NtrX in alphaproteobacteria

Abstract: Many signaling pathways that control cellular development, cell-cycle progression and nutritional versatility have been studied in Caulobacter crescentus. For example, it was suggested that the response regulator NtrX is conditionally essential for this bacterium and that it might be necessary for responding to a signal produced in phosphate-replete minimal medium. However, such signal has not been identified yet and the role of NtrX in C. crescentus biology remains elusive. Here, using wild-type C. crescentus and a strain with a chromosomally myc-tagged ntrX gene, we demonstrate that high concentrations of phosphate (10 mM) regulate ntrX transcription and the abundance of the protein. We also show that the pH of the medium acts as a switch able to regulate the phosphorylation status of NtrX, promoting its phosphorylation under mildly acidic conditions and its dephosphorylation at neutral pH. Moreover, we demonstrate that the ntrX gene is required for survival in environments with low pH and under acidic stress. Finally, we prove that NtrX phosphorylation is also triggered by low pH in Brucella abortus, a pathogenic alphaproteobacterium. Overall, our work contributes to deepen the general knowledge of this system and provides tools to elucidate the NtrX regulon.