Formation of Transient Protein Aggregate-like Centers Is a General Strategy Postponing Degradation of Misfolded Intermediates.

When misfolded intermediates accumulate during heat shock, the protein quality control system promotes cellular adaptation strategies. In Schizosaccharomyces pombe, thermo-sensitive proteins assemble upon stress into protein aggregate-like centers, PACs, to escape from degradation. The role of this protein deposition strategy has been elusive due to the use of different model systems and reporters, and to the addition of artificial inhibitors, which made interpretation of the results difficult. Here, we compare fission and budding yeast model systems, expressing the same misfolding reporters in experiments lacking proteasome or translation inhibitors. We demonstrate that mild heat shock triggers reversible PAC formation, with the collapse of both reporters and chaperones in a process largely mediated by chaperones. This assembly postpones proteasomal degradation of the misfolding reporters, and their Hsp104-dependent disassembly occurs during stress recovery. Severe heat shock induces formation of cytosolic PACs, but also of nuclear structures resembling nucleolar rings, NuRs, presumably to halt nuclear functions. Our study demonstrates that these distantly related yeasts use very similar strategies to adapt and survive to mild and severe heat shock and that aggregate-like formation is a general cellular scheme to postpone protein degradation and facilitate exit from stress.

Jarzynski equality on work and free energy: Crystal indentation as a case study.

Mathematical relations concerning particle systems require knowledge of the applicability conditions to become physically relevant and not merely formal. We illustrate this fact through the analysis of the Jarzynski equality (JE), whose derivation for Hamiltonian systems suggests that the equilibrium free-energy variations can be computational or experimentally determined in almost any kind of non-equilibrium processes. This apparent generality is surprising in a mechanical theory. Analytically, we show that the quantity called "work" in the Hamiltonian derivation of the JE is neither a thermodynamic quantity nor mechanical work, except in special circumstances to be singularly assessed. Through molecular dynamics simulations of elastic and plastic deformations induced via nano-indentation of crystalline surfaces that fall within the formal framework of the JE, we illustrate that the JE cannot be verified and that the results of this verification are process dependent.

Statistics of dislocation avalanches in FCC and BCC metals: dislocation mechanisms and mean swept distances across microsample sizes and temperatures.

Plastic deformation in crystalline materials consists of an ensemble of collective dislocation glide processes, which lead to strain burst emissions in micro-scale samples. To unravel the combined role of crystalline structure, sample size and temperature on these processes, we performed a comprehensive set of strict displacement-controlled micropillar compression experiments in conjunction with large-scale molecular dynamics and physics-based discrete dislocation dynamics simulations. The results indicate that plastic strain bursts consist of numerous individual dislocation glide events, which span over minuscule time intervals. The size distributions of these events exhibit a gradual transition from an incipient power-law slip regime (spanning [Formula: see text] 2.5 decades of slip sizes) to a large avalanche domain (spanning [Formula: see text] 4 decades of emission probability) at a cut-off slip magnitude [Formula: see text]. This cut-off slip provides a statistical measure to the characteristic mean dislocation swept distance, which allows for the scaling of the avalanche distributions vis-à-vis the archetypal dislocation mechanisms in face-centered cubic (FCC) and body-centered cubic (BCC) metals. Our statistical findings provide a new pathway to characterizing metal plasticity and towards comprehension of the sample size effects that limit the mechanical reliability in small-scale structures.

Comparing RAS with and without biofloc: Transcriptional response of immune-related genes in Litopenaeus vannamei post-larvae / Comparación de SAR con y sin biofloc: Respuesta transcripcional de genes relacionados con el sistema inmune en postlarvas de Litopenaeus vannamei / Comparando o SAR com e sem biofloc: Resposta transcricional de genes relacionados ao sistema imune em pós-larvas de Litopenaeus vannamei

Abstract Background: Shrimp farming is evolving from semi-intensive to hyper-intensive systems with biofloc technology and water recirculation systems. Objective: To evaluate the transcriptional response promoted by biofloc on shrimp (Litopenaeus vannamei) under a recirculating aquaculture system (RAS). Methods: Quantitative real-time RT-PCR was used to monitor seven key genes related to the immune system in shrimp post-larvae, reared in a RAS with and without biofloc (BF and no- BF). In addition, we present for the first time nucleotide sequences of ADP-ribosylation factor 4 (LvArf4) from Litopenaeus vannamei. Results: Transcripts for penaeidin3 (Pen3), penaeidin4 (Pen4), crustin, and Toll receptor (LvToll) genes were up-regulated between 3 and 24 h in both systems, and tumor necrosis factor receptor-associated factor 6 (TRAF6) in no-BF as an early response. Regarding differential expression between treatments, 13 occurrences were encountered. Nine that were higher in BF than in no-BF and four higher in no-BF than in BF. In some sample times, expression of Pen3, crustin, LvToll, TRAF6, IMD, and LvArf4 was higher in BF than in no-BF and in others, expression of Pen3, Pen4, and TRAF6 was higher in no-BF than in BF. Conclusions: BF modulates the transcription of genes related to the immune response in shrimp as an early response. However, the RAS with no-BF promotes a similar response.

Resumen Antecedentes: Los cultivos de camarón están evolucionando de sistemas semi-intensivos a hiper-intensivos con biofloc y con recirculación. Objetivo: Evaluar la respuesta transcripcional promovida por el biofloc en un sistema acuícola con recirculación (SAR). Métodos: Monitoreamos mediante RT-PCR cuantitativo siete genes relacionados con el sistema inmune en postlarvas de camarón cultivadas en un SAR con y sin biofloc (BF y no-BF). Además, presentamos por primera vez la secuencia de nucleótidos del factor de ribosilación 4 de ADP (LvArf4) de Litopenaeus vannamei. Resultados: Los genes penaeidina3 (Pen3), penaeidina4 (Pen4), Crustina y Toll (LvToll) se sobre-expresaron entre las 3 y 24 h en ambos sistemas, y el factor 6 asociado al factor de necrosis tumoral (TRAF6) en BF como una respuesta temprana. Con respecto a la expresión diferencial entre los tratamientos, se presentaron 13 ocurrencias. Nueve donde el BF fue mayor que sin-BF y cuatro donde el no-BF fue mayor que el BF. La expresión fue más alta en BF que en no-BF en Pen3, Crustin, LvToll, TRAF6, IMD y LvArf4. En contraste, la expresión fue mayor en no-BF en Pen3, Pen4 y TRAF6. Conclusión: el BF modula la transcripción de los genes relacionados con la respuesta inmune en camarón como una respuesta temprana. Sin embargo, el SAR sin-BF promueve una respuesta similar.

Resumo Antecedentes: A criação de camarões está evoluindo de sistemas semi-intensivos para hiper-intensivos como tecnologia de bioflocos e sistemas de recirculação. Objetivo: Avaliar a resposta transcricional promovida pelo biofloco em um sistema de aquicultura recirculante (SAR). Métodos: Utilizamos RT-PCR quantitativo em tempo real para monitorar sete genes-chave relacionados ao sistema imune em pós-larvas de camarão, criados em SAR com e sem bioflocos (BF e no-BF). Além disso, apresentamos pela primeira vez sequências nucleotídicas do fator de ribosilação do ADP 4 (LvArf4) de Litopenaeus vannamei. Resultados: Os resultados mostraram que o Penaeidina3 (PEN3), Penaeidina4 (Pen4), Crustina e Toll genes (LvToll) foram sobre-expressos entre 3 e 24 h em ambos os sistemas, e o Factor de Necrose do Receptor 6 associado e protuberância (TRAF6) no BF como uma resposta precoce. Com relação à expressão diferencial entre tratamentos, 13 ocorrências foram apresentadas. Nove onde o BF foi maior do que os não-BF e quatro onde o não-BF foi maior do que o BF. A expressão foi maior do que em BF não-BF em Pen3, Crustin, LvToll, TRAF6, IMD e LvArf4. Em contraste, a expressão foi mais elevada no não-BF em Pen3, Pen4 e TRAF6. Conclusões: O BF modula a transcrição de resposta imune relacionada no camarão como um genes de resposta precoce. No entanto, o SAR não BF promove uma resposta semelhante.

Comportamiento sexual y conocimiento sobre infecciones de transmisión sexual en estudiantes venezolanos de un liceo del municipio de Miranda / Sexual behavior and knowledge of sexually transmitted infections in Venezuelan students from a high school in municipality of Miranda

Se realizó un estudio descriptivo y comparativo, de corte longitudinal, de 201 estudiantes entre 11-17 años (de un universo de 220), de un liceo público de la localidad de Quisiro, del municipio de Miranda, en la República Bolivariana de Venezuela, con vistas a evaluar el comportamiento sexual y el conocimiento de infecciones de transmisión sexual, previo consentimiento informado de los padres y de la muestra en cuestión. El análisis de los datos se efectuó con el paquete estadístico SAS R, versión 9.3.1. En los integrantes de la serie, la actividad sexual era bastante común, con predominio de los que la iniciaron activamente entre los 14 y 15 años, poco uso de métodos anticonceptivos, mayor número de parejas sexuales en los varones, así como un mejor conocimiento acerca de las infecciones de transmisión sexual en el caso de las chicas.

A descriptive and longitudinal controlled study in 201 students aged 11-17 years (from a total of 220) of a public high school in Quisiro town, Miranda municipality in the Bolivarian Republic of Venezuela was conducted to evaluate sexual behavior and knowledge of sexually transmitted infections, with previous informed consent of the parents and of the sample in question. Data were analyzed using the SAS R statistical package, version 9.3.1. In the members of the series the sexual activity was quite common, with predominance of those that actively started it between 14 and 15 years, little use of birth-control methods, higher number of sexual partners for boys and a better knowledge of sexually transmitted infections for girls.

Planar defect nucleation and annihilation mechanisms in nanocontact plasticity of metal surfaces.

The incipient contact plasticity of metallic surfaces involves nucleation of crystalline defects. The present molecular dynamics simulations and nanoindentation experiments demonstrate that the current notion of nanocontact plasticity in fcc metals does not apply to high-strength bcc metals. We show that nanocontact plasticity in Ta-a model bcc metal-is triggered by thermal and loading-rate dependent (dynamic) nucleation of planar defects such as twins and unique {011} stacking fault bands. Nucleation of different planar defects depending on surface orientation leads to distinct signatures (pop ins) in the nanoindentation curves. Nanoscale plasticity is then ruled by an outstanding dynamical mechanism governing twin annihilation and subsequent emission of linear defects (full dislocations). While this investigation concerns Ta crystals, the present are landmark findings for other model bcc metals.