Algae-Bacteria Consortia as a Strategy to Enhance H2 Production

Biological hydrogen production by microalgae is a potential sustainable, renewable and clean source of energy. However, many barriers limiting photohydrogen production in these microorganisms remain unsolved. In order to explore this potential and make biohydrogen industrially affordable, the unicellular microalga Chlamydomonas reinhardtii is used as a model system to solve barriers and identify new approaches that can improve hydrogen production. Recently, Chlamydomonas–bacteria consortia have opened a new window to improve biohydrogen production. In this study, we review the different consortia that have been successfully employed and analyze the factors that could be behind the improved H2 production

Arginine is a component of the ammonium- CYG56 signalling cascade that represses genes of the nitrogen assimilation pathway in Chlamydomonas reinhardtii

Nitrogen assimilation and metabolism are essential processes for all living organisms, yet there is still much to be learnt on how they are regulated. The use of Chlamydomonas reinhardtii as a model system has been instrumental not only in identifying conserved regulation mechanisms that control the nitrogen assimilation pathway, but also in understanding how the intracellular nitrogen status regulates metabolic processes of industrial interest such as the synthesis of biolipids. While the genetic regulators that control the nitrogen pathway are successfully being unravelled, other layers of regulation have received less attention. Amino acids, for example, regulate nitrogen assimilation in certain organisms, but their role in Chlamydomonas has not thoroughly been explored. Previous results had suggested that arginine might repress key genes of the nitrogen assimilation pathway by acting within the ammonium negative signalling cascade, upstream of the nitric oxide (NO) inducible guanylate cyclase CYG56. We tested this hypothesis with a combination of genetic and chemical approaches. Antagonising the effects of arginine with an arginine biosynthesis mutant or with two chemical analogues released gene expression from ammonium mediated repression. The cyg56 and related non1 mutants, which are partially insensitive to ammonium repression, were also partially insensitive to repression by arginine. Finally, we show that the addition of arginine to the medium leads to an increase in intracellular NO. Our data reveal that arginine acts as a negative signal for the assimilation of nitrogen within the ammonium-CYG56 negative signalling cascade, and provide a connection between amino acid metabolism and nitrogen assimilation in microalgae

Credit Risk transmission in the European Banking Sector: The Case of the Subprime and the Eurozone Debt Crisis

El objetivo del presente trabajo es analizar en profundidad la transmisión del riesgo de crédito, aproximado por los CDS spreads, en el sector bancario europeo durante el periodo 2006-2012, intentando dar respuesta a diversas cuestiones: (i) ¿existe evidencia de transmisión del riesgo de crédito entre las entidades financieras europeas de la Eurozona y las que no pertenecen a dicha zona?, (ii) ¿es esta transmisión bidireccional o unidireccional?, (iii) concretamente, ¿qué países han liderado dicha transmisión?, y (iv) ¿cómo se ha visto afectada dicha transmisión con las recientes crisis financieras? Los resultados indican un cambio significativo en la transmisión del riesgo de crédito con el estallido de la crisis subprime, con un efecto notable proveniente de los bancos de la Eurozona hacia los que no pertenecen a dicha zona

Stenotrophomonas goyi sp. nov., a novel bacterium associated with the alga Chlamydomonas reinhardtii [version 2; peer review: 2 approved]

Background: A culture of the green algae Chlamydomonas reinhardtii was accidentally contaminated with three different bacteria in our laboratory facilities. This contaminated alga culture showed increased algal biohydrogen production. These three bacteria were independently isolated. Methods: The chromosomic DNA of one of the isolated bacteria was extracted and sequenced using PacBio technology. Tentative genome annotation (RAST server) and phylogenetic trees analysis (TYGS server) were conducted. Diverse growth tests were assayed for the bacterium and for the alga-bacterium consortium. Results: Phylogenetic analysis indicates that the bacterium is a novel member of the Stenotrophomonas genus that has been termed in this work as S. goyi sp. nov. A fully sequenced genome (4,487,389 base pairs) and its tentative annotation (4,147 genes) are provided. The genome information suggests that S. goyi sp. nov. is unable to use sulfate and nitrate as sulfur and nitrogen sources, respectively. Growth tests have confirmed the dependence on the sulfur-containing amino acids methionine and cysteine. S. goyi sp. nov. and Chlamydomonas reinhardtii can establish a mutualistic relationship when cocultured together. Conclusions: S. goyi sp. nov. could be of interest for the design of biotechnological approaches based on the use of artificial microalgae-bacteria multispecies consortia that take advantage of the complementary metabolic capacities of their different microorganisms

Giant cell granuloma of the maxilla: global management, review of literature and case report

Giant cell granuloma is a relatively rare benign entity but can be locally aggressive. Histologically characterized by intense proliferation of multinucleated giant cells and fibroblasts. Affects bone supported tissues. Definitive diagnosis is given by biopsy. Clinically manifest as a mass or nodule of reddish color and fleshy, occasionally ulcerated surface. They can range from asymptomatic to destructive lesions that grow quickly. It is a lesion to be considered in the differential diagnosis of osteolytic lesions affecting the maxilla or jaw. Its management passed from conservative treatment with intralesional infiltration of corticosteroids, calcitonin or interferon, to the surgical resection and reconstruction, for example with microvascular free flaps. Keywords: giant cell granuloma, intralesional injection, microvascular free flap, fibula

Is it possible to make the study of Biochemistry fun and enjoyable? The gamification to learn

La Gamificación es el empleo de mecánicas de juego con el fin de potenciar la motivación, la concentración, el esfuerzo y otros valores positivos comunes a todos los juegos. Se trata de una nueva y poderosa estrategia para influir y motivar a grupos de estudiantes. Memrise es una herramienta gratuita de aprendizaje online con cursos creados por su comunidad. Memrise permite aumentar la rapidez y la facilidad del aprendizaje, realizándose además de una forma amena. También, fomenta la competitividad entre los estudiantes a través de un sistema de puntuación. Los cursos Memrise son también de autoaprendizaje, a través de las Mems, que son frases cortas o bien imágenes que los estudiantes adjuntan de forma individual a cada una de las preguntas. Gracias a este proyecto se ha creado un curso Memrise de 1081 preguntas que puede ser utilizado para cualquier asignatura de bioquímica fundamental. Este curso se ha empleado en la asignatura bioquímica de primero de Enfermería y se ha analizado la utilización por parte del alumnado. Llegándose a la conclusión que su utilización ha sido muy notable por parte del alumnado y que ha repercutido positivamente en la preparación de los exámenes por parte del estudiante.Gamification is the use of game mechanics in order to enhance motivation, concentration, effort and other positive values common to all games. It is a new and powerful strategy to influence and motivate groups of students. Memrise is a free online learning tool with courses created by the community. Memrise allows you to increase the speed and ease of learning, done in an enjoyable way. Also, it encourages competitiveness among students through a scoring system. The Memrise courses are also self-learning, through the Mems, which are short sentences or images that students attach individually to each of the questions. Thanks to this project, a Memrise course has been created for any subject of fundamental Biochemistry. This course consists of 1081 questions for the subject Biochemistry of Nursing and has analyzed the use by students. Arriving at the conclusion that its use has been very remarkable on the part of the students and that it has had a positive impact on the student's preparation for the exams

Glucose uptake in Prochlorococcus: diversity of kinetics and effects on the metabolism

We have previously shown that Prochlorococcus sp. SS120 strain takes up glucose by using a multiphasic transporter encoded by the Pro1404 gene. Here, we studied the glucose uptake kinetics in multiple Prochlorococcus strains from different ecotypes, observing diverse values for the Ks constants (15–126.60 nM) and the uptake rates (0.48–6.36 pmol min-1 mg prot-1). Multiphasic kinetics was observed in all studied strains, except for TAK9803-2. Pro1404 gene expression studies during the 21st Atlantic Meridional Transect cruise showed positive correlation with glucose concentrations in the ocean. This suggests that the Pro1404 transporter has been subjected to diversification along the Prochlorococcus evolution, in a process probably driven by the glucose availabilities at the different niches it inhabits. The glucose uptake mechanism seems to be a primary transporter. Glucose addition induced detectable transcriptomic and proteomic changes in Prochlorococcus SS120, but photosynthetic efficiency was unaffected. Our studies indicate that glucose is actively taken up by Prochlorococcus, but its uptake does not significantly alter the trophic ways of this cyanobacterium, which continues performing photosynthesis. Therefore Prochlorococcus seems to remain acting as a fundamentally phototrophic organism, capable of using glucose as an extra resource of carbon and energy when available in the environment

Functional reconstruction after subtotal glossectomy in the surgical treatment of an uncommon and aggressive neoplasm in this location: primary malignant melanoma in the base of the tongue

Primary malignant melanoma of the oral cavity is a rare neoplasm, especially on the tongue. We report a case of mucosal melanoma at the base of the tongue, an extremely rare location (only about 30 cases have been reported in literature). The extension study doesn't revealed distant metastatic lesions. The patient was treated by subtotal glossectomy and bilateral functional neck dissection. Tongue is one of the most difficult structures to reconstruct, because of their central role in phonation, swallowing and airway protection. The defect was reconstructed with anterolateral thigh free flap. Surgical treatment was supplemented with adjuvant immunotherapy. The post-operative period was uneventful. At present, 24 months after surgery, patient is asymptomatic, there isn't evidence of recurrence of melanoma and he hasn't any difficulty in swallowing or phonation

Low oxygen levels contribute to improve photohydrogen production in mixotrophic non‑stressed Chlamydomonas cultures

Background: Currently, hydrogen fuel is derived mainly from fossil fuels, but there is an increasing interest in clean and sustainable technologies for hydrogen production. In this context, the ability of some photosynthetic microorganisms, particularly cyanobacteria and microalgae, to produce hydrogen is a promising alternative for renewable, clean-energy production. Among a diverse array of photosynthetic microorganisms able to produce hydrogen, the green algae Chlamydomonas reinhardtii is the model organism widely used to study hydrogen production. Despite the well-known fact that acetate-containing medium enhances hydrogen production in this algae, little is known about the precise role of acetate during this process. Results: We have examined several physiological aspects related to acetate assimilation in the context of hydrogen production metabolism. Measurements of oxygen and CO2 levels, acetate uptake, and cell growth were performed under different light conditions, and oxygenic regimes. We show that oxygen and light intensity levels control acetate assimilation and modulate hydrogen production. We also demonstrate that the determination of the contribution of the PSII-dependent hydrogen production pathway in mixotrophic cultures, using the photosynthetic inhibitor DCMU, can lead to dissimilar results when used under various oxygenic regimes. The level of inhibition of DCMU in hydrogen production under low light seems to be linked to the acetate uptake rates. Moreover, we highlight the importance of releasing the hydrogen partial pressure to avoid an inherent inhibitory factor on the hydrogen production. Conclusion: Low levels of oxygen allow for low acetate uptake rates, and paradoxically, lead to efficient and sustained production of hydrogen. Our data suggest that acetate plays an important role in the hydrogen production process, during non-stressed conditions, other than establishing anaerobiosis, and independent of starch accumulation. Potential metabolic pathways involved in hydrogen production in mixotrophic cultures are discussed. Mixotrophic nutrient-replete cultures under low light are shown to be an alternative for the simultaneous production of hydrogen and biomass