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.

Sensing the dissociation of a polymeric enzyme by means of an engineered intrinsic probe.

Abstract: One of the most remarkable characteristics of Brucella lumazine synthase (BLS) is its versatility to undergo reversible dissociation and reassociation as a polymeric scaffold. We have proposed a mechanism of dissociation and unfolding of BLS. Using static light scattering (SLS) analysis, we were able to demonstrate that the decameric assembly dissociates into two different conditions [pH 5 or 2M guanidinium chloride (GdnHCl) pH 7] forming stable folded pentamers. The transition from folded pentamers to unfolded monomers by GdnHCl denaturation is highly cooperative and can be measured by different spectroscopic techniques. In this work, we show the successful insertion of an intrinsic probe to study in more detail the equilibria described in previous publications. For that purpose, we performed single-point mutations of Phe residues 121 and 127, located at the pentamer-pentamer and monomer-monomer interface, respectively, to Trp residues. These mutations produced only a marginal perturbation of the BLS structure. We analyzed the unfolding and stability of the mutants through different techniques: far-and near-UV CD, SLS, dynamic light scattering, and fluorescence spectroscopy. The introduced intrinsic probe could be used to gain insights into the detailed folding and assembly mechanism of this protein.

Characterization of Intellectual disability and Autism comorbidity through gene panel sequencing

Abstract: Intellectual disability (ID) and autism spectrum disorder (ASD) are clinically and genetically heterogeneous diseases. Recent whole exome sequencing studies indicated that genes associated with different neurological diseases are shared across disorders and converge on common functional pathways. Using the Ion Torrent platform, we developed a low-cost next generation sequencing (NGS) gene panel that has been transferred into clinical practice, replacing single disease gene analyses for the early diagnosis of individuals with ID/ASD. The gene panel was designed using an innovative in silico approach based on disease networks and mining data from public resources to score disease-gene associations. We analyzed 150 unrelated individuals with ID and/or ASD and a confident diagnosis has been reached in 26 cases (17%). Likely pathogenic mutations have been identified in another 15 patients, reaching a total diagnostic yield of 27%. Our data also support the pathogenic role of genes recently proposed to be involved in ASD. Although many of the identified variants need further investigation to be considered disease-causing, our results indicate the efficiency of the targeted gene panel on the identification of novel and rare variants in patients with ID and ASD.

Response of the fungus Pseudocercospora griseola f. mesoamericana to Tricyclazole

Abstract: Pseudocercospora griseola, an anamorph of Mycosphaerella, causes Angular Leaf Spot (ALS). The mycelia and conidia from P. griseola are coloured due to the synthesis of 1,8 dihydroxynaphthalene (DHN)-melanin. The aim of this work was to identify in P. griseola f. mesoamericana isolate T4, a highly pigmented fungus, intermediary compounds as a result of the inhibition of melanin synthesis by tricyclazole, and to analyze at the structural level the localization of these dark pigments. The main metabolites were analyzed using ultraviolet matrix-assisted laser desorption-ionization mass spectrometry (UV–MALDI MS). Tricyclazole affected P. griseola f. mesoamericana in several different ways. The most evident effect was the reduction of melanin synthesis, and therefore diffusible shunt products were found and identified. Flaviolin was the main intermediate metabolite found in cultures supplemented with tricyclazole. This inhibitor, which affected pigmentation and the cell wall structure of mycelium, revealed macroscopically by the reduction in growth, decreased the stratification and deposition of melanin in the hyphal wall. These results suggest a possible role of tricyclazole to control ALS.

Calcium dynamics in tomato pollen tubes using the Yellow Cameleon 3.6 sensor

Abstract: In vitro tomato pollen tubes show a cytoplasmic calcium gradient that oscillates with the same period as growth. Pollen tube growth requires coordination between the tip-focused cytoplasmic calcium concentration ([Ca2+]cyt) gradient and the actin cytoskeleton. This [Ca2+]cyt gradient is necessary for exocytosis of small vesicles, which contributes to the delivery of new membrane and cell wall at the pollen tube tip. The mechanisms that generate and maintain this [Ca2+]cyt gradient are not completely understood. Here, we studied calcium dynamics in tomato (Solanum lycopersicum) pollen tubes using transgenic tomato plants expressing the Yellow Cameleon 3.6 gene under the pollen-specific promoter LAT52. We use tomato as an experimental model because tomato is a Solanaceous plant that is easy to transform, and has an excellent genomic database and genetic stock center, and unlike Arabidopsis, tomato pollen is a good system to do biochemistry. We found that tomato pollen tubes showed an oscillating tip-focused [Ca2+]cyt gradient with the same period as growth. Then, we used a pharmacological approach to disturb the intracellular Ca2+ homeostasis, evaluating how the [Ca2+]cyt gradient, pollen germination and in vitro pollen tube growth were affected. We found that cyclopiazonic acid (CPA), a drug that inhibits plant PIIA-type Ca2+-ATPases, increased [Ca2+]cyt in the subapical zone, leading to the disappearance of the Ca2+ oscillations and inhibition of pollen tube growth. In contrast, 2-aminoethoxydiphenyl borate (2-APB), an inhibitor of Ca2+ released from the endoplasmic reticulum to the cytoplasm in animals cells, completely reduced [Ca2+]cyt at the tip of the tube, blocked the gradient and arrested pollen tube growth. Although both drugs have antagonistic effects on [Ca2+]cyt, both inhibited pollen tube growth triggering the disappearance of the [Ca2+]cyt gradient. When CPA and 2-APB were combined, their individual inhibitory effects on pollen tube growth were partially compensated. Finally, we found that GsMTx-4, a peptide from spider venom that blocks stretch-activated Ca2+ channels, inhibited tomato pollen germination and had a heterogeneous effect on pollen tube growth, suggesting that these channels are also involved in the maintenance of the [Ca2+]cyt gradient. All these results indicate that tomato pollen tube is an excellent model to study calcium dynamics.

Draft Genome Sequence of Methylobacterium sp. Strain V23, Isolated from Accretion Ice of the Antarctic Subglacial Lake Vostok

Abstract: Here, we report the draft genome sequence of Methylobacterium sp. strain V23, a bacterium isolated from accretion ice of the subglacial Lake Vostok (3,592 meters below the surface). This genome makes possible the study of ancient and psychrophilic genes and proteins from a subglacial environment isolated from the surface for at least 15 million years.