Cristian Carrión

Background: Shoulder to Shoulder Global (STSG) recognizes anemia as a cause of morbidity among patients in Santo Domingo, Ecuador. Little research has been done to assess targetable anemia risk factors to serve as a foundation for future pharmacotherapeutic interventions. This study sought to characterize anemia in this population to lay the foundation for future preventive intervention. Methods: Cross-sectional data obtained from existing clinic records from 2010 to 2016 included hemoglobin/hematocrit, age, sex, pregnancy status, and respective community. Chi-square compared means to examine risk factors associated with anemia. Logistic regression and odds ratios (OR) were used to estimate risk factors associated with anemia. Results: Of the 1145 (86.2%) subjects with complete data for analysis, 67.2% were female, 33% were children under five, 1.6% were pregnant, and 42.8% were anemic. Subjects were distributed throughout the seven communities with 11.2% presenting from an indigenous community. Risk factors for anemia were age <5 years and presenting from the communities of Plan de Vivienda, Los Naranjos, or El Bua. Neither sex nor pregnancy were significantly associated risk factors with anemia. Conclusions: Risk factors for anemia in this population have not previously been determined. In this study, risk factors were age group <5 years and presentation from three different communities. This study pioneered the use of an electronic medical record database in this setting. A limitation of the study is its observational cross-sectional design with a study population that allows for selection bias. Additional research should evaluate the effectiveness of STSG health interventions on anemia.

Las carreras de Biología de la FCNyM de la UNLP poseen los mismos planes de estudios desde hace al menos 34 años. La ausencia de espacios institucionalizados y regulares de discusión respecto del perfil de formación, ha contribuido a la modificación de contenidos en los espacios fragmentarios de las cátedras, sin una mirada de conjunto. Es a partir del año 2008 que ha sido posible un proceso continuo de cambio curricular con la participación de todos los actores de esta unidad académica. En este trabajo se desarrolla una sistematización analítica y crítica sobre los antecedentes curriculares y los sujetos y discursos que predominan en el proceso actual de cambio curricular.

Este trabajo de tesis pretende profundizar el conocimiento de las vacuolas asociadas a la senescencia (VAS) a través de tres temáticas: - el desarrollo, entendido como la variación temporal de las VAS, su biogénesis y el efecto de moduladores de la senescencia; - la caracterización de la actividad biológica de las VAS participando en el desmantelamiento del aparato fotosintético; - y la relación entre el mecanismo de autofagia y el desarrollo de las VAS. En general, para abordar estos objetos de estudios se empleó un sistema sencillo y frecuentemente empleado en trabajos sobre senescencia foliar. El modelo de senescencia inducida permite trabajar en un sistema relativamente homogéneo y reproducible. Consiste en separar las hojas de la planta, tratarlas con un precursor de la hormona etileno, denominado etefón, y almacenarlas en oscuridad. De esta manera, la senescencia es inducida por el corte y la oscuridad, y sincronizada a nivel tisular por el tratamiento hormonal.

HvPAP14 is a cysteine protease found in association with thylakoid membranes. Among its putative substrates are proteins such as LHCB1, LHCB5, PSBO, and RbcL, as revealed in overexpressing barley plants.

Chlorophyll (Chl) loss is the main visible symptom of senescence in leaves. The initial steps of Chl degradation operate within the chloroplast, but the observation that “senescence‐associated vacuoles” (SAVs) contain Chl raises the question whether SAVs might also contribute to Chl breakdown. Previous confocal microscope observations (Martínez et al. 2008) showed many SAVs containing Chl. Isolated SAVs contained Chl a and b (with a Chl a/b ratio close to 5) and smaller amounts of chlorophyllide a. Pheophytin a and Pheophorbide a were formed after incubation of SAVs at 30°C in darkness, suggesting the presence of Chl‐degrading activities in SAVs. Chl in SAVs was bound to a number of “green bands”. In the most‐abundant green band of SAVs, Western blot analysis showed the presence of PSI Chl‐binding proteins, including the PsaA protein of PSI reaction center and the apoproteins of light‐harvesting complexes (Lhca 1‐4). This was confirmed by ‐1 measurements of 77K fluorescence emission spectra showing a single emission peak at around 730 nm in SAVs, ‐2 mass spectrometry of the most prominent green band with the slowest electrophoretic mobility, and ‐3 immunofluorescence detection of PsaA in SAVs observed through confocal microscopy. Incubation of SAVs at 30°C in darkness caused a steady decrease in PsaA levels. Overall, these results indicate that SAVs may be involved in the degradation of PSI proteins and their associated chlorophylls during senescence of leaves.

Degradation of chloroplasts and chloroplast components is a distinctive feature of leaf senescence. In spite of its importance in the nutrient economy of plants, knowledge about the mechanism(s) involved in the breakdown of chloroplast proteins is incomplete. A novel class of vacuoles, “senescence-associated vacuoles” (SAVs), characterized by intense proteolytic activity appear during senescence in chloroplast-containing cells of leaves. Since SAVs contain some chloroplast proteins, they are candidate organelles to participate in chloroplast breakdown. In this review we discuss the characteristics of SAVs, and their possible involvement in the degradation of Rubisco, the most abundant chloroplast protein. Finally, SAVs are compared with other extra-plastidial protein degradation pathways operating in senescing leaves.

Breakdown of leaf proteins, particularly chloroplast proteins, is a massive process in senescing leaves. In spite of its importance in internal N recycling, the mechanism(s) and the enzymes involved are largely unknown. Senescence-associated vacuoles (SAVs) are small, acidic vacuoles with high cysteine peptidase activity. Chloroplast-targeted proteins re-localize to SAVs during senescence, suggesting that SAVs might be involved in chloroplast protein degradation. SAVs were undetectable in mature, non-senescent tobacco leaves. Their abundance, visualized either with the acidotropic marker Lysotracker Red or by green fluorescent protein (GFP) fluorescence in a line expressing the senescence-associated cysteine protease SAG12 fused to GFP, increased during senescence induction in darkness, and peaked after 2–4 d, when chloroplast dismantling was most intense. Increased abundance of SAVs correlated with higher levels of SAG12 mRNA. Activity labelling with a biotinylated derivative of the cysteine protease inhibitor E-64 was used to detect active cysteine proteases. The two apparently most abundant cysteine proteases of senescing leaves, of 40kDa and 33kDa were detected in isolated SAVs. Rubisco degradation in isolated SAVs was completely blocked by E-64. Treatment of leaf disks with E-64 in vivo substantially reduced degradation of Rubisco and leaf proteins. Overall, these results indicate that SAVs contain most of the cysteine protease activity of senescing cells, and that SAV cysteine proteases are at least partly responsible for the degradation of stromal proteins of the chloroplast.