El ciclo de Randle, el precario vínculo entre azúcares y grasas

Obesity is a growing global health concern, closely related to cardiovascular diseases. Understanding the correlation between excessive sugar consumption and the formation of fat deposits, described in the Randle cycle, will allow us to have a better grasp on metabolic processes that disrupt the balance between fat formation and degradation processes. The goal of this review is to expand and update the information about the Randle cycle and describe their different levels of regulation. In addition, the participation of mTORC1 and the AMP dependent Kinase (AMPK) during the postprandial and fasting states is described.La obesidad es un problema de salud global, asociada con enfermedades cardiovasculares. El análisis de la relación existente entre el elevado consumo de glucosa y la concomitante formación de depósitos de grasa, descrita por el ciclo de Randle, permitirá desarrollar una comprensión de los procesos metabólicos involucrados en el balance entre la formación y la degradación de los lípidos. Esta revisión tiene como objetivo, proporcionar una actualización del ciclo y de sus diferentes niveles de regulación, así como la participación de mTORC1 y la cinasa dependiente de AMP (AMPK) durante el estado postprandial y de ayuno.

Levaduras adaptadas al frío: el tesoro biotecnológico de la Antártica

Yeasts are microscopic organisms that are distributed in the biomes of the whole Earth, so some yeasts species exhibit diverse metabolic adaptations that allow them to proliferate in extreme environments. Yeasts that inhabit the Antarctica represent a relatively unexplored group of cold-adapted fungi. This review describes some of the metabolic adaptations that allow yeasts to inhabit extreme environments such as those in the Antarctica. This review also addresses the relevant considerations to know whether a yeast is extremophilic, as well as the criteria used to classify by its growth and temperature. The role of carotenoid and lipid biosynthesis pathways to mitigate reactive oxygen species generated by oxidative stress in pigmented and oleaginous yeasts including the Rhodotorula genus is described. Further, this review also considers the importance of basic research in oleaginous yeast from Antarctica and the development of biotechnological applications.Las levaduras son organismos microscópicos que están distribuidos en toda la Tierra, de modo que algunas han adaptado su metabolismo para proliferar en ambientes extremos. Las levaduras que habitan en la Antártica son un grupo de microorganismos adaptados al frío que han sido poco estudiadas. En esta revisión se describen algunas de las adaptaciones metabólicas que les permiten habitar en ambientes extremos, por ejemplo, el de la Antártica. También se abordan las consideraciones relevantes para saber si una levadura es extremófila, así como los criterios utilizados para clasificar a las levaduras por crecimiento y temperatura. Además, se explica el papel de las vías de biosíntesis de carotenoides y lípidos que están involucradas en contrarrestar a las especies reactivas de oxígeno generadas por estrés oxidante en levaduras pigmentadas y oleaginosas del género Rhodotorula. La revisión también considera aspectos de investigación básica y la importancia de las levaduras oleaginosas de la Antártica para el desarrollo de algunas aplicaciones biotecnológicas

DNA Methyltransferases: From Evolution to Clinical Applications

DNA methylation is an epigenetic mark that living beings have used in different environments. The MTases family catalyzes DNA methylation. This process is conserved from archaea to eukaryotes, from fertilization to every stage of development, and from the early stages of cancer to metastasis. The family of DNMTs has been classified into DNMT1, DNMT2, and DNMT3. Each DNMT has been duplicated or deleted, having consequences on DNMT structure and cellular function, resulting in a conserved evolutionary reaction of DNA methylation. DNMTs are conserved in the five kingdoms of life: bacteria, protists, fungi, plants, and animals. The importance of DNMTs in whether methylate or not has a historical adaptation that in mammals has been discovered in complex regulatory mechanisms to develop another padlock to genomic insurance stability. The regulatory mechanisms that control DNMTs expression are involved in a diversity of cell phenotypes and are associated with pathologies transcription deregulation. This work focused on DNA methyltransferases, their biology, functions, and new inhibitory mechanisms reported. We also discuss different approaches to inhibit DNMTs, the use of non-coding RNAs and nucleoside chemical compounds in recent studies, and their importance in biological, clinical, and industry research

Los isoprenoides como fuente de biocombustibles

The fossil fuels have negative effects on the environment thus in last years the concern about the supplies of petroleum has increased, therefore the implementation of renewable energies is a necessity, these energies also have to be economic and environment-friendly. The biofuels, are environment-friendly energy that can be obtained from renewable sources as corn, lignocellulose, citrus peel, or from the lipids of microorganism as cyanobacteria, genetically modified bacteria Escherichia coli and yeast as Yarrowia lipolytica and Rhodosporidium toruloides. Both yeasts have the capacity to accumulate 70% of lipid in dry biomass, unlike Y. lipolytica, the R. toruloides accumulate carotenoids, a kind of terpenoid with many applications in pharmaceutics and food industries. Moreover, this yeast has the ability to metabolize a variety of sugars as glucose, xylose, mannose, and sucrose, while the yeasts Y. lipolytic and Saccharomyces cerevisiae are unable to metabolize the pentose xylose. The R. toruloides also can tolerate variations in temperature and pH reason why is one of the yeast more explored to achieve the production of biomolecules as lipids and terpenoids, from which is possible to obtain biofuels and biofuels additives. The biofuels obtained from yeast, due to its origin, are classified as biofuels of third generation, and energetic and structurally are similar to fossil fuels, therefore some isoprenoids are used in the aviation industry and can be used for diesel engines. In this review, we describe some properties of the isoprenoids as precursors of biofuels and additives.Los combustibles fósiles tienen efectos negativos sobre el medio ambiente y, en los últimos años, la preocupación por el agotamiento de las fuentes de este tipo de energía se ha incrementado, por lo que es necesario la implementación de energías alternas que sean amigables con el medio ambiente, que sean económicas y similares o mejores en cuanto al rendimiento energético que las actuales. Los biocombustibles son una fuente de energía que se obtienen de los lípidos de plantas como el maíz, o de los lípidos de microorganismos como las cianobacterias, las bacterias y las levaduras oleaginosas como Rhodosporidium toruloides y Yarrowia lipolytica, estas últimas con una capacidad de acumular hasta el 70% de lípidos en relación a su peso seco. R. toruloides también tiene la particularidad de acumular carotenoides, un tipo de terpeno que tiene importancia comercial. Los biocombustibles que se obtienen de las levaduras, por su origen, se clasifican como de tercera generación, y son energética y estructuralmente similares a los que se extraen de los fósiles, por lo que algunos isoprenoides pueden ser utilizados en la industria de la aviación y automotiz para motores diesel.R. toruloides tiene la ventaja de integrar a su metabolismo una amplia variedad de azúcares: glucosa, xilosa, manosa, sacarosa, mientras que S. cerevisiae y Y. lipolytica son incapaces de asimilar la xilosa. R. toruloides también tolera variaciones en la temperatura y el pH. Después de Y. lipolytica, R. toruloides es una de las levaduras más exploradas para la producción de biomoléculas, como los lípidos y los terpenos, a partir de los cuales es posible obtener combustibles y aditivos de combustibles. En esta revisión nos enfocamos en describir algunas propiedades de los isoprenoides y sus aplicaciones como combustibles y aditivos de combustible

Carbon and Nitrogen Sources Have No Impact on the Organization and Composition of <i>Ustilago maydis</i> Respiratory Supercomplexes

Respiratory supercomplexes are found in mitochondria of eukaryotic cells and some bacteria. A hypothetical role of these supercomplexes is electron channeling, which in principle should increase the respiratory chain efficiency and ATP synthesis. In addition to the four classic respiratory complexes and the ATP synthase, U. maydis mitochondria contain three type II NADH dehydrogenases (NADH for reduced nicotinamide adenine dinucleotide) and the alternative oxidase. Changes in the composition of the respiratory supercomplexes due to energy requirements have been reported in certain organisms. In this study, we addressed the organization of the mitochondrial respiratory complexes in U. maydis under diverse energy conditions. Supercomplexes were obtained by solubilization of U. maydis mitochondria with digitonin and separated by blue native polyacrylamide gel electrophoresis (BN-PAGE). The molecular mass of supercomplexes and their probable stoichiometries were 1200 kDa (I1:IV1), 1400 kDa (I1:III2), 1600 kDa (I1:III2:IV1), and 1800 kDa (I1:III2:IV2). Concerning the ATP synthase, approximately half of the protein is present as a dimer and half as a monomer. The distribution of respiratory supercomplexes was the same in all growth conditions. We did not find evidence for the association of complex II and the alternative NADH dehydrogenases with other respiratory complexes

The mitochondrial alternative oxidase Aox1 is needed to cope with respiratory stress but dispensable for pathogenic development in <i>Ustilago maydis</i>

<div><p>The mitochondrial alternative oxidase is an important enzyme that allows respiratory activity and the functioning of the Krebs cycle upon disturbance of the respiration chain. It works as a security valve in transferring excessive electrons to oxygen, thereby preventing potential damage by the generation of harmful radicals. A clear biological function, besides the stress response, has so far convincingly only been shown for plants that use the alternative oxidase to generate heat to distribute volatiles. In fungi it was described that the alternative oxidase is needed for pathogenicity. Here, we investigate expression and function of the alternative oxidase at different stages of the life cycle of the corn pathogen <i>Ustilago maydis</i> (Aox1). Interestingly, expression of Aox1 is specifically induced during the stationary phase suggesting a role at high cell density when nutrients become limiting. Studying deletion strains as well as overexpressing strains revealed that Aox1 is dispensable for normal growth, for cell morphology, for response to temperature stress as well as for filamentous growth and plant pathogenicity. However, during conditions eliciting respiratory stress yeast-like growth as well as hyphal growth is strongly affected. We conclude that Aox1 is dispensable for the normal biology of the fungus but specifically needed to cope with respiratory stress.</p></div

Expression of Aox1-Gfp.

<p><b>A)</b> Expression of Aox1-Gfp dependent on OD and growth phase. Aox1-Gfp is expressed in the stationary phase. Aox1-Gfp was detected by anti-Gfp. Tub1 serves as loading control. <b>B)</b> Expression of Aox1-Gfp is not dependent on acidification of the media. Western Blot, growth curve, and pH values of the media (unbuffered = CM; buffered = CM + 100 mM MOPS) depending on time. <b>C)</b> Sporidia of FB2, FB2Potef:aox1-Gfp, and FB2Potef:5'UTR-aox1-Gfp showing that aox1-Gfp under the control of the otef-promoter is expressed irrespective of the growth phase.</p