Clonaje, expresión y caracterización estructural de una nueva metalotioneína de crustáceos a partir de la langosta panulirus argus. Estudios de su función en la mitocondria

Las metalotieneinas constituyen una superfamilia de proteínas de bajo peso molecular (menos de 9 kg), ricas en residuos de cisteína, que le confieren una alta capacidad para enlazar iones metálicos. A pesar de que el primer miembro de esta gran familia fue descubierto en 1957, aun no se ha podido establecer con precisión el papel biológico de estas proteínas, existiendo muy pocos trabajos que hayan contribuido a esclarecer sus funciones invertebrados. El presente trabajo describe la caracterización de una nueva metalotioneina (mtpa) obtenida, por vía recombinante, a partir del hepatopáncreas de la langosta del Caribe panulirus argus. Mediante rt-pcr semicuantitativa se analiza la expresión de mtpa en hepatopancreas, intestino, tejido nervioso y musculo; detectándose mrna de mtpa en todos los tejidos examinados, aunque la mayor expresión se observa en el hepatopáncreas. Estos resultados demuestran por primera vez la expresión de mrna de metalotioneina en crustáceos, no solo en tejidos digestivos, sino también en musculo y tejido nervioso. Adicionalmente, se analiza la inducción por cd del mrna de mtpa en explantes de diferentes tejidos de la langosta, observándose el mayor nivel de inducción en el tejido nervioso. La secuencia aminoacidica de mtpa, deducida a partir del cdna obtenido, tiene 59 aminoácidos y presenta homología con el resto de las secuencias de metalotioneinas de crustáceos conocidas. Curiosamente, mtpa tiene una cisteina extra (19 en total) en la región correspondiente al dominio c-terminal, en comparación con la mayoría de las metalotioneinas de crustáceos, lo cual podría implicar una mayor capacidad para unir metales. Sin embargo, como se demuestra por 2 técnicas diferentes de análisis (esi-ms y txrf), esta profeina una 6 iones zn2+, al igual que las metalotioneinas de crustáceos que presentan 18 cisteínas. Por homología con las estructuras de los dominios c-terminal de mt-1 de calinectes sapidus (1dmc) y de la mt de homarus americanus (1j5l), se muestra un modelo preliminar de la estructura tridimensional del dominio c-terminal de mtpa, en el cual la cisteina extra estaria orientada hacia el exterior y por tanto no formaría parte del "cluster" zn-s. Por otro lado, mtpa-zn2+6 inhibe la cadena de transporte electrónico mitocondrial y, como consecuencia, aumenta los niveles intramitocondriales de ros, mientras que tpa tiene un efecto contrario. A pesar de esto, mtpa ejerce un efecto protector contra el estrés oxidativo, ya que la estimulación de la producción de ros por esta proteína, es mucho menor en comparación con la provocada por cantidades equivalentes de zn2+ libre. El hecho de que mtpa afecta al consumo de oxigeno mitocondrial es hepatopancreas de crustáceos constituye el primer estudio de este tipo en invertebrados y concuerda con otros resultados descritos en la literatura para mamíferos, que sugieren una relación de las metalotioneinas con el metabolismo energético

A KD-trees based method for fast radiation source representation for virtual reality dosimetry applications in nuclear safeguards and security

[EN] With the aim of demonstrating the concrete advantages that novel technologies such as Virtual (VR) can provide to the nuclear industry, the authors of this paper have been working on the development of a VR based simulator of a gamma dose rate detector for training purposes, to be applied in the field of nuclear security and safety. Historically in nuclear science, simulating gamma dose rate transport has had a series of requirements, most importantly the accuracy of the computation. When embedding this dose rate computation in the environment of a VR based application, a second and opposing key requirement appears: real time performance. Meeting this requirement is only possible if a fast method to compute gamma radiation is used. In order to achieve this target the authors have been working in ways of improving the efficiency of the Point-Kernel method by reducing its computational effort. This paper presents the latest step in this pursuit of efficiency; a novel method based on a non-regular kernel approach, combined with a KD-tree based volume division method. Devised to reduce as much as possible the number of points that represent the volume of the source while aiming at retaining sufficient dose computation accuracy. (C) 2016 Elsevier Ltd. All rights reserved.This project is fully funded by the Institute of Transuranium Elements of the European Commission's Joint Research Centre, Ispra site, Italy.Moltó-Caracena, T.; Vendrell Vidal, E.; Goncalves, JG.; Peerani, P. (2017). A KD-trees based method for fast radiation source representation for virtual reality dosimetry applications in nuclear safeguards and security. Progress in Nuclear Energy. 95:78-83. https://doi.org/10.1016/j.pnucene.2016.12.001S78839

A variable point kernel dosimetry method for virtual reality simulation applications in nuclear safeguards and security

© 2013 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper presents an algorithm to calculate gamma dose rates intended for virtual reality (VR) applications. It dynamically adapts the method to cope with both accuracy and time requirements. Given the real-time constraints imposed by VR applications, more accurate, but computationally intensive stochastic algorithms (e.g., Monte Carlo) are not suited to this task. On the opposite end, a Point Kernel (PK) method can be effective in some cases with as little as one point (mono PK) to define a source, in contrast with the millions of points that Monte Carlo computes. Simple mono PK codes may lack the desired accuracy in some circumstances, requiring a more detailed source representation. In this work, a novel method is presented which automatically estimates the appropriate level of detail for a source's volumetric representation, then generates a non-regular mesh model and subsequently computes the dose rate via a PK method, performing this three-step process in real time.This work was supported by the European Commission's Joint Research Centre Ph.D. grant program.Moltó Caracena, T.; Gonçalves, JGM.; Peerani, P.; Vendrell Vidal, E. (2013). A variable point kernel dosimetry method for virtual reality simulation applications in nuclear safeguards and security. IEEE Transactions on Nuclear Science. 60(5):3862-3871. doi:10.1109/TNS.2013.2279411S3862387160

Tissue-specific effects of central leptin on the expression of genes involved in lipid metabolism in liver and white adipose tissue

Copyright (2007) The Endocrine Society .The paper can be found at the following URL on the website http://endo.endojournals.org

Regulation of insulin-stimulated glucose uptake in rat white adipose tissue upon chronic central leptin infusion: effects on adiposity

Copyright (2011) The Endocrine Society .The paper can be found at the following URL on the website http://endo.endojournals.org

Ageing alters the lipid sensing process in the hypothalamus of Wistar rats. Effect of food restriction

Lipids regulate a wide range of biological processes. The mechanisms by which fatty acids (FA) and its metabolites influence the hypothalamic regulation of energy homeostasis have been highly studied. However, the effect of ageing and food restriction (FR) on this process is unknown. Herein, we analyzed the gene expression, protein and phosphorylation levels of hypothalamic enzymes and transcription factors related to lipid metabolism. Experiments were performed in male Wistar rats of 3-, 8- and 24-month-old Wistar rats fed ad libitum (AL), as ageing model. Besides, 5- and 21-month-old rats were subjected to a moderate FR protocol (equivalent to ≈ 80% of normal food intake) for three months before the sacrifice. Aged Wistar rats showed a situation of chronic lipid excess as a result of an increase in de novo FA synthesis and FA levels that reach the brain, contributing likely to the development of central leptin and insulin resistance. We observe a hypothalamic downregulation of AMP-activated protein kinase (AMPK) and stearoyl-CoA desaturase (SCD1) and an increase of carnitine palmitoyltransferase-1c (CPT1c) expression

Polygenic contribution to the relationship of loneliness and social isolation with schizophrenia

Previous research suggests an association of loneliness and social isolation (LNL-ISO) with schizophrenia. Here, we demonstrate a LNL-ISO polygenic score contribution to schizophrenia risk in an independent case-control sample (N = 3,488). We then subset schizophrenia predisposing variation based on its effect on LNL-ISO. We find that genetic variation with concordant effects in both phenotypes shows significant SNP-based heritability enrichment, higher polygenic contribution in females, and positive covariance with mental disorders such as depression, anxiety, attention-deficit hyperactivity disorder, alcohol dependence, and autism. Conversely, genetic variation with discordant effects only contributes to schizophrenia risk in males and is negatively correlated with those disorders. Mendelian randomization analyses demonstrate a plausible bi-directional causal relationship between LNL-ISO and schizophrenia, with a greater effect of LNL-ISO liability on schizophrenia than vice versa. These results illustrate the genetic footprint of LNL-ISO on schizophrenia

A role for insulator elements in the regulation of gene expression response to hypoxia

Hypoxia inducible factor (HIF) up-regulates the transcription of a few hundred genes required for the adaptation to hypoxia. This restricted set of targets is in sharp contrast with the widespread distribution of the HIF binding motif throughout the genome. Here, we investigated the transcriptional response of GYS1 and RUVBL2 genes to hypoxia to understand the mechanisms that restrict HIF activity toward specific genes. GYS1 and RUVBL2 genes are encoded by opposite DNA strands and separated by a short intergenic region (~1 kb) that contains a functional hypoxia response element equidistant to both genes. However, hypoxia induced the expression of GYS1 gene only. Analysis of the transcriptional response of chimeric constructs derived from the intergenic region revealed an inhibitory sequence whose deletion allowed RUVBL2 induction by HIF. Enhancer blocking assays, performed in cell culture and transgenic zebrafish, confirmed the existence of an insulator element within this inhibitory region that could explain the differential regulation of GYS1 and RUVBL2 by hypoxia. Hence, in this model, the selective response to HIF is achieved with the aid of insulator elements. This is the first report suggesting a role for insulators in the regulation of differential gene expression in response to environmental signals

An insulator embedded in the chicken α-globin locus regulates chromatin domain configuration and differential gene expression

Genome organization into transcriptionally active domains denotes one of the first levels of gene expression regulation. Although the chromatin domain concept is generally accepted, only little is known on how domain organization impacts the regulation of differential gene expression. Insulators might hold answers to address this issue as they delimit and organize chromatin domains. We have previously identified a CTCF-dependent insulator with enhancer-blocking activity embedded in the 5′ non-coding region of the chicken α-globin domain. Here, we demonstrate that this element, called the αEHS-1.4 insulator, protects a transgene against chromosomal position effects in stably transfected cell lines and transgenic mice. We found that this insulator can create a regulated chromatin environment that coincides with the onset of adult α-globin gene expression. Furthermore, such activity is in part dependent on the in vivo regulated occupancy of CTCF at the αEHS-1.4 element. Insulator function is also regulated by CTCF poly(ADP-ribosyl)ation. Our results suggest that the αEHS-1.4 insulator contributes in organizing the chromatin structure of the α-globin gene domain and prevents activation of adult α-globin gene expression at the erythroblast stage via CTCF