Noise Processing by MicroRNA-Mediated Circuits: the Incoherent Feed-Forward Loop, Revisited

The intrinsic stochasticity of gene expression is usually mitigated in higher eukaryotes by post-transcriptional regulation channels that stabilise the output layer, most notably protein levels. The discovery of small non-coding RNAs (miRNAs) in specific motifs of the genetic regulatory network has led to identifying noise buffering as the possible key function they exert in regulation. Recent in vitro} and in silico studies have corroborated this hypothesis. It is however also known that miRNA-mediated noise reduction is hampered by transcriptional bursting in simple topologies. Here, using stochastic simulations validated by analytical calculations based on van Kampen's expansion, we revisit the noise-buffering capacity of the miRNA-mediated Incoherent Feed Forward Loop (IFFL), a small module that is widespread in the gene regulatory networks of higher eukaryotes, in order to account for the effects of intermittency in the transcriptional activity of the modulator gene. We show that bursting considerably alters the circuit's ability to control static protein noise. By comparing with other regulatory architectures, we find that direct transcriptional regulation significantly outperforms the IFFL in a broad range of kinetic parameters. This suggests that, under pulsatile inputs, static noise reduction may be less important than dynamical aspects of noise and information processing in characterising the performance of regulatory elements.Comment: 25 pages (Main Text and Supplementary Information), 5 figure

Noise processing by microRNA-mediated circuits: The Incoherent Feed-Forward Loop, revisited

The intrinsic stochasticity of gene expression is usually mitigated in higher eukaryotes by post-transcriptional regulation channels that stabilise the output layer, most notably protein levels. The discovery of small non-coding RNAs (miRNAs) in specific motifs of the genetic regulatory network has led to identifying noise buffering as the possible key function they exert in regulation. Recent in vitro and in silico studies have corroborated this hypothesis. It is however also known that miRNA-mediated noise reduction is hampered by transcriptional bursting in simple topologies. Here, using stochastic simulations validated by analytical calculations based on van Kampen's expansion, we revisit the noise-buffering capacity of the miRNA-mediated Incoherent Feed Forward Loop (IFFL), a small module that is widespread in the gene regulatory networks of higher eukaryotes, in order to account for the effects of intermittency in the transcriptional activity of the modulator gene. We show that bursting considerably alters the circuit's ability to control static protein noise. By comparing with other regulatory architectures, we find that direct transcriptional regulation significantly outperforms the IFFL in a broad range of kinetic parameters. This suggests that, under pulsatile inputs, static noise reduction may be less important than dynamical aspects of noise and information processing in characterising the performance of regulatory elements

“Think about your math teachers”: a narrative bridge between future primary teachers’ identity and their school experience

Pre-service teachers approach their professional learning in mathematics with a complex set of needs and wants. These needs and wants are strongly affected by the tension deriving from the realisation of the gap between what an individual wants to become as a mathematics teacher (his/her ideal of mathematics teacher) and what he/she believes to be at present. Professional identity as a mathematics teacher can be seen as a continuous development arising from this gap. For these reason, both as researchers and as teacher educators, it appears significant to study what ideals of positive and negative mathematics teachers the future teachers have

Food Design as a Strategy for the Global Community

The paper aims to identify the role of Design Culture in adopting food and gastronomic practices as strategic tools to enhance dialogues between different cultures. The research analyses the cases in which contemporary Design Culture adopts food as a possibility of social inclusion, understanding of the global flows of people, transformation techniques, and novel rituals. Food and food cycles can be interpreted as "language", as well as an opportunity to create circular business activities based on the rediscovery and on the strengthening of the links between territories and communities in a globalised scenario increasingly attentive to the experiences of fusion between cultures. Design culture can become a mediator, a facilitator and a promoter of solutions and models of integration between cultural components we commonly consider "strong" and "weak", "host" and "settled", "traditional" and "modern", "slow" and "fast", "typical" and "atopic". Thus an "open" scenario is outlined in which projects and researches oriented to the diffusion of more sustainable and "community centred" food cultures are renewed and take on new meanings. New cultures emerge which, while keeping their cultural roots, evolve into a transcultural society. The Design Culture is called to recognise and co-design these new “food acts” of the contemporary transcultural societies

Imaging follow-up after liver transplantation

Liver transplantation (LT) represents the best treatment for end-stage chronic liver disease, acute liver failure and early stages of hepatocellular carcinoma. Radiologists should be aware of surgical techniques to distinguish a normal appearance from pathological findings. Imaging modalities, such as ultrasound, CT and MR, provide for rapid and reliable detection of vascular and biliary complications after LT. The role of imaging in the evaluation of rejection and primary graft dysfunction is less defined. This article illustrates the main surgical anastomoses during LT, the normal appearance and complications of the liver parenchyma and vascular and biliary structures.Liver transplantation (LT) represents the best treatment for end-stage chronic liver disease, acute liver failure and early stages of hepatocellular carcinoma. Radiologists should be aware of surgical techniques to distinguish a normal appearance from pathological findings. Imaging modalities, such as ultrasound, CT and MR, provide for rapid and reliable detection of vascular and biliary complications after LT. The role of imaging in the evaluation of rejection and primary graft dysfunction is less defined. This article illustrates the main surgical anastomoses during LT, the normal appearance and complications of the liver parenchyma and vascular and biliary structures

Interdisciplinariedad universitaria: una propuesta según Leonardo Polo

Resumen: En este trabajo se presenta una propuesta sobre la interdisciplinariedad universitaria. Generalmente la interdisciplinariedad se aborda de modo analítico, este estudio pretende ofrecer un enfoque sistémico. De esta manera se entiende que es mucho más probable —especialmente en el momento actual— obtener mayor extensión y hondura en el planteamiento de modo tal que logre quizás encontrar un camino para reunificar los diversos aportes de cada disciplina en la búsqueda de soluciones de fondo. Se evita el análisis porque se considera que aborda la cuestión de modo parcial y no llega a integrar. Se considera que los aportes del filósofo español Leonardo Polo, podrían ofrecer algunas claves para atisbar luz en este difícil momento, al tema presentado. El autor ofrece una descripción de la universidad y de las raíces de la crisis en la que se encuentra. Concretamente, explica cómo el desgajamiento de los saberes superiores y la ruptura de la unidad entre ellos, sería, según él, el origen de esta desvinculación de las ciencias entre sí y sus consecuencias. Su propuesta se plantea en dos sentidos. Polo ofrece una teoría del conocimiento que, se considera que podría resolver la cuestión desde lo teórico. Su teoría del conocimiento —por cierto amplia y reunitiva— intenta dar cuenta de la importancia de la interdisciplinariedad en vinculación con los diversos niveles del conocer humano, de un modo ordenado y vinculante. A la vez, el autor plantea que hay una vertiente personal o subjetiva que entronca con el modo en que se dan las interrelaciones entre los miembros de la comunidad universitaria. Polo explica que la falta de interdisciplinariedad, más que un problema teórico —que indudablemente lo es—, es una cuestión de orden superior, personal. Las personas que investigan en las diversas ciencias son superiores a los saberes; unir a las personas entre sí es un asunto de apertura y aceptación personal. Se exponen estas claves para que puedan ser consideradas por los docentes universitarios y quizás logren otorgar alguna pista que permita superar la situación actual

Interdisciplinariedad universitaria: una propuesta según Leonardo Polo

This paper presents a proposal on university interdisciplinarity from a methodical systemic approach. It is understood that this method can provide amplitude and depth to reunify the diverse contributions of each discipline. The approach of the Spanish philosopher Leonardo Polo, could offer some keys to shed light on the subject. It will offer a description of the university and the roots of its crisis. The breakup of superior knowledge and the rupture of unity among them would be, according to Polo, the origin of this separation of sciences from each other and their consequences. His proposal is presented in two ways. It offers a theory of knowledge - broad and reuniting - that links the different levels of human knowledge. But he points out that what is relevant is the personal side that connects with the interrelationships between university professors.En este trabajo se presenta una propuesta sobre la interdisciplinariedad universitaria. Generalmente la interdisciplinariedad se aborda de modo analítico, este estudio pretende ofrecer un enfoque sistémico. De esta manera se entiende que es mucho más probable -especialmente en el momento actual- obtener mayor extensión y hondura en el planteamiento de modo tal que logre quizás encontrar un camino para reunificar los diversos aportes de cada disciplina en la búsqueda de soluciones de fondo. Se evita el análisis porque se considera que aborda la cuestión de modo parcial y no llega a integrar. Se considera que los aportes del filósofo español Leonardo Polo, podrían ofrecer algunas claves para atisbar luz en este difícil momento, al tema presentado. El autor ofrece una descripción de la universidad y de las raíces de la crisis en la que se encuentra. Concretamente, explica cómo el desgajamiento de los saberes superiores y la ruptura de la unidad entre ellos, sería, según él, el origen de esta desvinculación de las ciencias entre sí y sus consecuencias. Su propuesta se plantea en dos sentidos. Polo ofrece una teoría del conocimiento que, se considera que podría resolver la cuestión desde lo teórico. Su teoría del conocimiento - por cierto amplia y reunitiva - intenta dar cuenta de la importancia de la interdisciplinariedad en vinculación con los diversos niveles del conocer humano, de un modo ordenado y vinculante. A la vez, el autor plantea que hay una vertiente personal o subjetiva que entronca con el modo en que se dan las interrelaciones entre los miembros de la comunidad universitaria. Polo explica que la falta de interdisciplinariedad, más que un problema teórico - que indudablemente lo es -, es una cuestión de orden superior, personal. Las personas que investigan en las diversas ciencias son superiores a los saberes; unir a las personas entre sí es un asunto de apertura y aceptación personal. Se exponen estas claves para que puedan ser consideradas por los docentes universitarios y quizás logren otorgar alguna pista que permita superar la situación actual