Análisis económico de la evolución de un agrosistema de manejo agroecológico en etapa de consolidación

Los agrosistemas de manejo agroecológico suelen ser reconocidos por su contribución hacia la sustentabilidad desde las dimensiones Ambiental y Social, mas suele señalarse como un desafío el mejorar su contribución desde la dimensión Económica. En este trabajo se describe la evaluación económica de un agrosistema fruti hortícola de manejo agroecológico en etapa de consolidación, en dos años sucesivos. Para ello se midieron las variables Eficiencia, Productividad y Seguridad a través de una serie de indicadores. Como principales resultados se observa que la familia cumple sus objetivos, que son la autosuficiencia alimentaria y la generación de excedentes, en ese orden prioritario. También se observó que, en el camino de la consolidación, los indicadores económicos han mejorado de un año al otro, lo que puede señalar una tendencia positiva.Agroecological management agricultural systems are often recognized for their contribution to sustainability from environmental and social dimensions, most often noted as a challenge to improve its contribution from the Economic dimension. In this paper the economic evaluation of horticultural farms with agroecological management in a consolidation phase, in two successive years is described. To do the Efficiency, Productivity and Safety variables were measured through a series of indicators. The main results shows that the family fulfills its objectives, which are food self-sufficiency and generating surpluses, in that order of priority. It was also noted that in the way of consolidation, economic indicators have improved from one year to another, which may indicate a positive trend.Eje: A1: Sistemas de producción de base agroecológicaFacultad de Ciencias Agrarias y Forestale

Budding yeast ATM/ATR control meiotic double-strand break (DSB) levels by down-regulating Rec114, an essential component of the DSB-machinery

An essential feature of meiosis is Spo11 catalysis of programmed DNA double strand breaks (DSBs). Evidence suggests that the number of DSBs generated per meiosis is genetically determined and that this ability to maintain a pre-determined DSB level, or "DSB homeostasis", might be a property of the meiotic program. Here, we present direct evidence that Rec114, an evolutionarily conserved essential component of the meiotic DSB-machinery, interacts with DSB hotspot DNA, and that Tel1 and Mec1, the budding yeast ATM and ATR, respectively, down-regulate Rec114 upon meiotic DSB formation through phosphorylation. Mimicking constitutive phosphorylation reduces the interaction between Rec114 and DSB hotspot DNA, resulting in a reduction and/or delay in DSB formation. Conversely, a non-phosphorylatable rec114 allele confers a genome-wide increase in both DSB levels and in the interaction between Rec114 and the DSB hotspot DNA. These observations strongly suggest that Tel1 and/or Mec1 phosphorylation of Rec114 following Spo11 catalysis down-regulates DSB formation by limiting the interaction between Rec114 and DSB hotspots. We also present evidence that Ndt80, a meiosis specific transcription factor, contributes to Rec114 degradation, consistent with its requirement for complete cessation of DSB formation. Loss of Rec114 foci from chromatin is associated with homolog synapsis but independent of Ndt80 or Tel1/Mec1 phosphorylation. Taken together, we present evidence for three independent ways of regulating Rec114 activity, which likely contribute to meiotic DSBs-homeostasis in maintaining genetically determined levels of breaks

Quasistatic delamination of sandwich-like Kirchhoff-Love plates

A quasistatic rate-independent adhesive delamination problem of laminated plates with a finite thickness is considered. By letting the thickness of the plates go to zero, a rate-independent delamination model for a laminated Kirchhoff-Love plate is obtained as limit of these quasistatic processes. The same dimension reduction procedure is eventually applied to processes which are sensitive to delamination modes, namely opening vs. shearing is distinguishe

Recruitment of the mitotic exit network to yeast centrosomes couples septin displacement to actomyosin constriction

The Mitotic Exit Network (MEN) promotes mitotic exit and cytokinesis but if and how MEN independently controls these two processes is unclear. Here, the authors report that MEN displaces septins from the cell division site to promote actomyosin ring constriction, independently of MEN control of mitotic exit

Cdc7p-Dbf4p Regulates Mitotic Exit by Inhibiting Polo Kinase

Cdc7p-Dbf4p is a conserved protein kinase required for the initiation of DNA replication. The Dbf4p regulatory subunit binds Cdc7p and is essential for Cdc7p kinase activation, however, the N-terminal third of Dbf4p is dispensable for its essential replication activities. Here, we define a short N-terminal Dbf4p region that targets Cdc7p-Dbf4p kinase to Cdc5p, the single Polo kinase in budding yeast that regulates mitotic progression and cytokinesis. Dbf4p mediates an interaction with the Polo substrate-binding domain to inhibit its essential role during mitosis. Although Dbf4p does not inhibit Polo kinase activity, it nonetheless inhibits Polo-mediated activation of the mitotic exit network (MEN), presumably by altering Polo substrate targeting. In addition, although dbf4 mutants defective for interaction with Polo transit S-phase normally, they aberrantly segregate chromosomes following nuclear misorientation. Therefore, Cdc7p-Dbf4p prevents inappropriate exit from mitosis by inhibiting Polo kinase and functions in the spindle position checkpoint