The Institute for Biotechnology and Bioengineering (IBB)

The Laboratório Associado Institute for Biotechnology and Bioengineering (IBB) is a research unit aiming to be a strategic infrastructure for the development of the Portuguese R&D and innovation policies in the areas of Biotechnology, Bioengineering, Biomaterials and Life, Biomedical and Agricultural Sciences. IBB combines its R&D activities with advanced higher education, technology transfer, consulting and services, with the aim of fostering the industrial, health, agriculture and environmental sectors

Acoustic determination of thermophysical properties and critical parameters for R404A and critical line of x CO2+(1− x) R404A

The thermophysical properties and critical parameters for the alternative refrigerant R404A (52 wt % of 1,1,1- trifluoroethane (R143a) + 44 wt % of pentafluoroethane (R125) + 4 wt % of 1,1,1,2-tetrafluoroethane (R134a)) were investigated using two different acoustic techniques. The critical behavior of the system xCO2 + (1 - x)R404A was also investigated. Experimental data of speed of sound in liquid R404A from 258 K to 338 K and pressures up to 65 MPa were measured using a pulse-echo method. Derived thermodynamic properties are calculated, combining our experimental data with density and isobaric heat capacity values published by other authors. Measurements of the critical temperature Tc and pressure pc on (R404A) and mixtures of xCO2 + (1 - x)R404A were performed using another simple ultrasonic time-delay technique. The binary critical line was determined over the whole composition range showing that this system deviates only slightly from ideality since the critical line is a continuous line. The Peng-Robinson equation of state with conventional mixing and combining rules was used to correlate the binary experimental data.info:eu-repo/semantics/publishedVersio

Acoustic determination of thermophysical properties and critical parameters for R410A and critical line of x CO2+(1− x) R410A

The thermophysical properties and critical parameters for the alternative refrigerant R410A (a near azeotropic refrigerant mixture containing difluoromethane (R32) and pentafluoroethane (R125) (50 wt % of each)) were investigated using two different acoustic techniques. The critical behavior of the system xCO2 + (1 - x)R410A was also investigated. Experimental data of speed of sound in liquid R410A from (253 to 338) K and pressures up to 65 MPa were measured using a pulse-echo method. Derived thermodynamic properties were calculated, combining our experimental data with density and isobaric heat capacity values published by other authors. Measurements of the critical temperature Tc and pressure pc on (R410A) and mixtures of xCO2 + (1 - x)R410A were performed using another simple ultrasonic time-delay technique. The binary critical line was determined over the whole composition range, showing that this system deviates only slightly from ideality since the critical line is a continuous line. The Peng-Robinson equation of state with conventional mixing and combining rules was used to correlate the binary experimental data.info:eu-repo/semantics/publishedVersio

Preimplantation development regulatory pathway construction through a text-mining approach

BACKGROUND: The integration of sequencing and gene interaction data and subsequent generation of pathways and networks contained in databases such as KEGG Pathway is essential for the comprehension of complex biological processes. We noticed the absence of a chart or pathway describing the well-studied preimplantation development stages; furthermore, not all genes involved in the process have entries in KEGG Orthology, important information for knowledge application with relation to other organisms. RESULTS: In this work we sought to develop the regulatory pathway for the preimplantation development stage using text-mining tools such as Medline Ranker and PESCADOR to reveal biointeractions among the genes involved in this process. The genes present in the resulting pathway were also used as seeds for software developed by our group called SeedServer to create clusters of homologous genes. These homologues allowed the determination of the last common ancestor for each gene and revealed that the preimplantation development pathway consists of a conserved ancient core of genes with the addition of modern elements. CONCLUSIONS: The generation of regulatory pathways through text-mining tools allows the integration of data generated by several studies for a more complete visualization of complex biological processes. Using the genes in this pathway as "seeds" for the generation of clusters of homologues, the pathway can be visualized for other organisms. The clustering of homologous genes together with determination of the ancestry leads to a better understanding of the evolution of such process

Determinantes Nacionais e Setoriais da Estrutura de Capital na América Latina

This study identified the role of the national environment (the Macroeconomy, Financial Development and Institutional Quality) and industry characteristics (Munificence, Dynamism, Concentration, Life Cycle, Technological Efficiency Dispersion, Product Quality Dispersion, Customer Bargaining Power and Supplier Bargaining Power) on debt of 612 listed companies from 7 Latin American countries (Argentina, Brazil, Chile, Colombia, Mexico, Peru and Venezuela). For comparison purposes, the analysis is also extended to 847 U.S. companies. The period of study is 1996-2009 and the analysis employed a Hierarchical Linear Model, which controls the effects according to the level of the variables (country, industry, time and firm). The results suggest that Financial Development eases access to external funds and Institutional Quality is negatively related to firm Leverage. The research also finds evidence that institutional quality can promote asymmetrical development between stock markets and credit markets

Hidden heterochromatin: Characterization in the Rodentia species Cricetus cricetus, Peromyscus eremicus (Cricetidae) and Praomys tullbergi (Muridae)

The use of in situ restriction endonuclease (RE) (which cleaves DNA at specific sequences) digestion has proven to be a useful technique in improving the dissection of constitutive heterochromatin (CH), and in the understanding of the CH evolution in different genomes. In the present work we describe in detail the CH of the three Rodentia species, Cricetus cricetus, Peromyscus eremicus (family Cricetidae) and Praomys tullbergi (family Muridae) using a panel of seven REs followed by C-banding. Comparison of the amount, distribution and molecular nature of C-positive heterochromatin revealed molecular heterogeneity in the heterochromatin of the three species. The large number of subclasses of CH identified in Praomys tullbergi chromosomes indicated that the karyotype of this species is the more derived when compared with the other two genomes analyzed, probably originated by a great number of complex chromosomal rearrangements. The high level of sequence heterogeneity identified in the CH of the three genomes suggests the coexistence of different satellite DNA families, or variants of these families in these genomes

Antioxidant pathways are up-regulated during biological nitrogen fixation to prevent ROS-induced nitrogenase inhibition in Gluconacetobacter diazotrophicus

Gluconacetobacter diazotrophicus, an endophyte isolated from sugarcane, is a strict aerobe that fixates N2. This process is catalyzed by nitrogenase and requires copious amounts of ATP. Nitrogenase activity is extremely sensitive to inhibition by oxygen and reactive oxygen species (ROS). However, the elevated oxidative metabolic rates required to sustain biological nitrogen fixation (BNF) may favor an increased production of ROS. Here, we explored this paradox and observed that ROS levels are, in fact, decreased in nitrogen-fixing cells due to the up-regulation of transcript levels of six ROS-detoxifying genes. A cluster analyses based on common expression patterns revealed the existence of a stable cluster with 99.8% similarity made up of the genes encoding the α-subunit of nitrogenase Mo–Fe protein (nifD), superoxide dismutase (sodA) and catalase type E (katE). Finally, nitrogenase activity was inhibited in a dose-dependent manner by paraquat, a redox cycler that increases cellular ROS levels. Our data revealed that ROS can strongly inhibit nitrogenase activity, and G. diazotrophicus alters its redox metabolism during BNF by increasing antioxidant transcript levels resulting in a lower ROS generation. We suggest that careful controlled ROS production during this critical phase is an adaptive mechanism to allow nitrogen fixation