Regulation of Myc transcription by an enhancer cluster dedicated to pluripotency and early embryonic expression.

MYC plays various roles in pluripotent stem cells, including the promotion of somatic cell reprogramming to pluripotency, the regulation of cell competition and the control of embryonic diapause. However, how Myc expression is regulated in this context remains unknown. The Myc gene lies within a ~ 3-megabase gene desert with multiple cis-regulatory elements. Here we use genomic rearrangements, transgenesis and targeted mutation to analyse Myc regulation in early mouse embryos and pluripotent stem cells. We identify a topologically-associated region that homes enhancers dedicated to Myc transcriptional regulation in stem cells of the pre-implantation and early post-implantation embryo. Within this region, we identify elements exclusively dedicated to Myc regulation in pluripotent cells, with distinct enhancers that sequentially activate during naive and formative pluripotency. Deletion of pluripotency-specific enhancers dampens embryonic stem cell competitive ability. These results identify a topologically defined enhancer cluster dedicated to early embryonic expression and uncover a modular mechanism for the regulation of Myc expression in different states of pluripotency.

P53 and BCL-2 family proteins PUMA and NOXA define competitive fitness in pluripotent cell competition.

Cell Competition is a process by which neighboring cells compare their fitness. As a result, viable but suboptimal cells are selectively eliminated in the presence of fitter cells. In the early mammalian embryo, epiblast pluripotent cells undergo extensive Cell Competition, which prevents suboptimal cells from contributing to the newly forming organism. While competitive ability is regulated by MYC in the epiblast, the mechanisms that contribute to competitive fitness in this context are largely unknown. Here, we report that P53 and its pro-apoptotic targets PUMA and NOXA regulate apoptosis susceptibility and competitive fitness in pluripotent cells. PUMA is widely expressed specifically in pluripotent cells in vitro and in vivo. We found that P53 regulates MYC levels in pluripotent cells, which connects these two Cell Competition pathways, however, MYC and PUMA/NOXA levels are independently regulated by P53. We propose a model that integrates a bifurcated P53 pathway regulating both MYC and PUMA/NOXA levels and determines competitive fitness.

Obtention of fatty acids and phenolic compounds from Colombian cashew (Anacardium occidentale) nut shells using pyrolysis: towards a sustainable biodiesel production.

Sustainable management of non-edible agricultural residues of cashew nut production is a concern in Colombia. Therefore, this study aimed to study the fatty acid content of a pyrolytic liquid obtained from cashew nut shells (CNSs) from the Vichada region in Colombia. Transesterification of pyrolytic liquid was conducted to obtain biodiesel at the micro-scale as the first approach for this valorization route. Proximal analysis of samples was carried out using advanced analytical techniques (UHPLC-MS and CG-MS) whereas phenolic content and antioxidant activity were determined. The production yield of pyrolytic liquid was 69.15 ± 5.07% weight (wt.), at 550 °C and 2h of pyrolysis and the liquid was rich in fatty acids (∼70% wt.) and long-chain phenols (∼18% wt.). Among the phenolic compounds in liquid, mainly unsaturated C15:4 cardanol was identified (82.1 ± 5.5 mg/g), whereas the antioxidant activity of pyrolytic liquid was 0.714 ± 0.030 TE/g. Moreover, the biodiesel yield was 81% using catalyst sodium methoxide (12% v), and 50 °C and 26 min for the reaction. The obtained biodiesel in the hexane fraction was rich in methyl trans-8-octadecanoate (20.9 % wt.) and methyl palmitate (14.3 % wt.), being the representative compounds in the biodiesel. Therefore, the results indicated that thermal conversion of CNSs for obtaining biodiesel on a one-step process is a suitable strategy for the management of toxic and non-edible cashew residues. Finally, this is the first work of its kind that propose in detail the composition of pyrolytic liquid obtained from Colombian cashew nut residues under the proximate analysis approach and using advanced analytical techniques.

Chemical composition and bioactive compounds of cashew (Anacardium occidentale) apple juice and bagasse from Colombian varieties.

Cashew nut production generates large amounts of cashew apple as residue. In Colombia, cashew cultivation is increasing together with the concerns on residue management. The objective of this study was to provide the first chemical, physical and thermal decomposition characterization of cashew apple from Colombian varieties harvested in Vichada, Colombia. This characterization was focused to identify the important bioactive and natural compounds that can be further valorized in the formulation of food, nutraceuticals, and pharmacological products. The results obtained in this study are helpful to portray the cashew apple as a potential by-product due to its renewable nature and valuable composition, instead of seeing it just as an agricultural residue. For that, cashew apples of Regional 8315 and Mapiria varieties were studied. The natural juice (cashew apple juice) that was extracted from the cashew apples and the remanent solids (cashew apple bagasse) were separately analyzed. The HPLC analytical technique was used to determine the concentration of bioactive compounds, structural carbohydrates, and soluble sugars that constitute this biomass. Spectrophotometric techniques were used to determine the concentration of tannins, carotenoids, and total polyphenols. Mineral content and antioxidant activity (DPPH and ABTS assays) were determined in the biomass. Also, the thermal decomposition under an inert atmosphere or pyrolysis was performed on cashew apple bagasse. The varieties of cashew apple studied in this work showed similar content of bioactive compounds, total phenolic content, and structural carbohydrates. However, the Mapiria variety showed values slightly higher than the Regional 8315. Regarding cashew apple juice, it is rich in tannins and ascorbic acid with values of 191 mg/100 mL and 70 mg/100 mL, respectively, for Mapiria variety. Additionally, the principal reservoir of bioactive compounds and constitutive carbohydrates was the cashew apple bagasse. About 50 wt.% of it was composed of cellulose and hemicellulose. Also, in the bagasse, the ascorbic acid content was in a range of 180-200 mg/100 g, which is higher than other fruits and vegetables. Moreover, alkaloids were identified in cashew apples. The maximum value of antioxidant activity (DPPH assay: 405 TEs/g) was observed in the bagasse of Mapiria variety. The bagasse thermal decomposition started around 150 °C when the structural carbohydrates and other constitutive substances started to degrade. After thermogravimetric analysis, a remanent of 20% of the initial weight suggested the formation of a rich-carbon solid, which could correspond to biochar. Therefore, the cashew apple harvested in Vichada is a valuable reservoir of a wide range of biomolecules that potentially could be valorized into energy, foods, and pharmacologic applications. Nevertheless, future work is necessary to describe the complex compounds of this residual biomass that are still unknown.

Effect of Nutritional Factors and Copper on the Regulation of Laccase Enzyme Production in Pleurotus ostreatus.

This research aimed to establish the relationship between carbon-nitrogen nutritional factors and copper sulfate on laccase activity (LA) by Pleurotus ostreatus. Culture media composition was tested to choose the nitrogen source. Yeast extract (YE) was selected as a better nitrogen source than ammonium sulfate. Then, the effect of glucose and YE concentrations on biomass production and LA as response variables was evaluated using central composite experimental designs with and without copper. The results showed that the best culture medium composition was glucose 45 gL-1 and YE 15 gL-1, simultaneously optimizing these two response variables. The fungal transcriptome was obtained in this medium with or without copper, and the differentially expressed genes were found. The main upregulated transcripts included three laccase genes (lacc2, lacc6, and lacc10) regulated by copper, whereas the principal downregulated transcripts included a copper transporter (ctr1) and a regulator of nitrogen metabolism (nmr1). These results suggest that Ctr1, which facilitates the entry of copper into the cell, is regulated by nutrient-sufficiency conditions. Once inside, copper induces transcription of laccase genes. This finding could explain why a 10-20-fold increase in LA occurs with copper compared to cultures without copper when using the optimal concentration of YE as nitrogen sources.

Regulation of Mother-to-Offspring Transmission of mtDNA Heteroplasmy.

mtDNA is present in multiple copies in each cell derived from the expansions of those in the oocyte. Heteroplasmy, more than one mtDNA variant, may be generated by mutagenesis, paternal mtDNA leakage, and novel medical technologies aiming to prevent inheritance of mtDNA-linked diseases. Heteroplasmy phenotypic impact remains poorly understood. Mouse studies led to contradictory models of random drift or haplotype selection for mother-to-offspring transmission of mtDNA heteroplasmy. Here, we show that mtDNA heteroplasmy affects embryo metabolism, cell fitness, and induced pluripotent stem cell (iPSC) generation. Thus, genetic and pharmacological interventions affecting oxidative phosphorylation (OXPHOS) modify competition among mtDNA haplotypes during oocyte development and/or at early embryonic stages. We show that heteroplasmy behavior can fall on a spectrum from random drift to strong selection, depending on mito-nuclear interactions and metabolic factors. Understanding heteroplasmy dynamics and its mechanisms provide novel knowledge of a fundamental biological process and enhance our ability to mitigate risks in clinical applications affecting mtDNA transmission.

Myc is dispensable for cardiomyocyte development but rescues Mycn-deficient hearts through functional replacement and cell competition.

Myc is considered an essential transcription factor for heart development, but cardiac defects have only been studied in global Myc loss-of-function models. Here, we eliminated Myc by recombining a Myc floxed allele with the Nkx2.5Cre driver. We observed no anatomical, cellular or functional alterations in either fetuses or adult cardiac Myc-deficient mice. We re-examined Myc expression during development and found no expression in developing cardiomyocytes. In contrast, we confirmed that Mycn is essential for cardiomyocyte proliferation and cardiogenesis. Mosaic Myc overexpression in a Mycn-deficient background shows that Myc can replace Mycn function, recovering heart development. We further show that this recovery involves the elimination of Mycn-deficient cells by cell competition. Our results indicate that Myc is dispensable in cardiomyocytes both during cardiogenesis and for adult heart homeostasis, and that Mycn is exclusively responsible for cardiomyocyte proliferation during heart development. Nonetheless, our results show that Myc can functionally replace Mycn We also show that cardiomyocytes compete according to their combined Myc and Mycn levels and that cell competition eliminates flawed cardiomyocytes, suggesting its relevance as a quality control mechanism in cardiac development.

Metabolomic profile and nucleoside composition of Cordyceps nidus sp. nov. (Cordycipitaceae): A new source of active compounds.

Cordyceps sensu lato is a genus of arthropod-pathogenic fungi, which have been used traditionally as medicinal in Asia. Within the genus, Ophiocordyceps sinensis is the most coveted and expensive species in China. Nevertheless, harvesting wild specimens has become a challenge given that natural populations of the fungus are decreasing and because large-scale culture of it has not yet been achieved. The worldwide demand for products derived from cultivable fungal species with medicinal properties has increased recently. In this study, we propose a new species, Cordyceps nidus, which parasitizes underground nests of trapdoor spiders. This species is phylogenetically related to Cordyceps militaris, Cordyceps pruinosa, and a sibling species of Cordyceps caloceroides. It is found in tropical rainforests from Bolivia, Brazil, Colombia and Ecuador. We also investigated the medicinal potential of this fungus based on its biochemical properties when grown on four different culture media. The metabolic profile particularly that of nucleosides, in polar and non-polar extracts was determined by UPLC, and then correlated to their antimicrobial activity and total phenolic content. The metabolome showed a high and significant dependency on the substrate used for fungal growth. The mass intensities of nucleosides and derivative compounds were higher in natural culture media in comparison to artificial culture media. Among these compounds, cordycepin was the predominant, showing the potential use of this species as an alternative to O. sinensis. Furthermore, methanol fractions showed antimicrobial activity against gram-positive bacteria, and less than 3.00 mg of gallic acid equivalents per g of dried extract were obtained when assessing its total phenolic content by modified Folin-Ciocalteu method. The presence of polyphenols opens the possibility of further exploring the antioxidant capacity and the conditions that may enhance this characteristic. The metabolic composition and biochemical activity indicate potential use of C. nidus in pharmaceutical applications.

Myc overexpression enhances of epicardial contribution to the developing heart and promotes extensive expansion of the cardiomyocyte population.

Myc is an essential regulator of cell growth and proliferation. Myc overexpression promotes the homeostatic expansion of cardiomyocyte populations by cell competition, however whether this applies to other cardiac lineages remains unknown. The epicardium contributes signals and cells to the developing and adult injured heart and exploring strategies for modulating its activity is of great interest. Using inducible genetic mosaics, we overexpressed Myc in the epicardium and determined the differential expansion of Myc-overexpressing cells with respect to their wild type counterparts. Myc-overexpressing cells overcolonized all epicardial-derived lineages and showed increased ability to invade the myocardium and populate the vasculature. We also found massive colonization of the myocardium by Wt1Cre-derived Myc-overexpressing cells, with preservation of cardiac development. Detailed analyses showed that this contribution is unlikely to derive from Cre activity in early cardiomyocytes but does not either derive from established epicardial cells, suggesting that early precursors expressing Wt1Cre originate the recombined cardiomyocytes. Myc overexpression does not modify the initial distribution of Wt1Cre-recombined cardiomyocytes, indicating that it does not stimulate the incorporation of early expressing Wt1Cre lineages to the myocardium, but differentially expands this initial population. We propose that strategies using epicardial lineages for heart repair may benefit from promoting cell competitive ability.

Validez en test adaptativos informatizados: alternativa para evaluar población con limitaciones visuales / Validade em testes adaptativos computadorizados: alternativa para avaliar população com deficiência visual / Validity in computerized adaptive testing: An alternative to assess visually impaired individuals

Este artículo centra su interés en la importancia de la validez dentro de los procesos de evaluación psicológica cuando se pretende evaluar a personas invidentes o con baja visión, y en el desarrollo de los Test Adaptativos Informatizados (TAI) como una alternativa para la evaluación de esta población. Se presenta una revisión sobre el concepto de validez a partir de las aproximaciones contemporáneas dominantes, y se habla acerca del desarrollo de los TAI, el problema de su validez y los alcances de esta tecnología como una alternativa para evaluar personas con baja visión o invidentes. Finalmente, este trabajo deja abierta la posibilidad para futuros desarrollos e investigaciones en torno a otras alternativas de evaluación con equidad para poblaciones con discapacidad física.(AU)

Este artigo centra o seu interesse na importância da validade dentro dos processos de avaliação psicológica de pessoas cegas ou com baixa visão e no desenvolvimento dos Testes Adaptativos Computadorizados (TAC) como uma alternativa para a avaliação dessa população. Apresenta-se uma revisão sobre o conceito de validade a partir das abordagens contemporâneas dominantes e sobre o desenvolvimento dos TAC, o problema da sua validade e os alcances dessa tecnologia como uma alternativa para avaliar pessoas cegas. Finalmente, o trabalho deixa em aberto a possibilidade de futuros desenvolvimentos e pesquisas sobre alternativas de avaliação com equidade para a população com deficiência física.(AU)

This article focuses on the importance of validity in the process of psychological evaluation, especially when the evaluation is intended for people with visual impairment, and about the development of the Computerized Adaptive Testing (CAT) as an alternative for the assessment of this population. First, a review of the main controversies about the concept of validity and the development of Computerized Adaptive Test is presented. Then, topics related to validity in CAT and scope, technological limitations, and the challenges of its use as an alternative to evaluate the visual impairment population are discussed. Finally, possibilities for future developments and research on high quality alternative assessment for populations with physical disabilities are set forth.(AU)

Validez en test adaptativos informatizados: alternativa para evaluar población con limitaciones visuales / Validade em testes adaptativos computadorizados: alternativa para avaliar população com deficiência visual / Validity in computerized adaptive testing: an alternative to assess visually impaired individuals

Este artículo centra su interés en la importancia de la validez dentro de los procesos de evaluación psicológica cuando se pretende evaluar a personas invidentes o con baja visión, y en el desarrollo de los Test Adaptativos Informatizados (TAI) como una alternativa para la evaluación de esta población. Se presenta una revisión sobre el concepto de validez a partir de las aproximaciones contemporáneas dominantes, y se habla acerca del desarrollo de los TAI, el problema de su validez y los alcances de esta tecnología como una alternativa para evaluar personas con baja visión o invidentes. Finalmente, este trabajo deja abierta la posibilidad para futuros desarrollos e investigaciones en torno a otras alternativas de evaluación con equidad para poblaciones con discapacidad física.

Este artigo centra o seu interesse na importância da validade dentro dos processos de avaliação psicológica de pessoas cegas ou com baixa visão e no desenvolvimento dos Testes Adaptativos Computadorizados (TAC) como uma alternativa para a avaliação dessa população. Apresenta-se uma revisão sobre o conceito de validade a partir das abordagens contemporâneas dominantes e sobre o desenvolvimento dos TAC, o problema da sua validade e os alcances dessa tecnologia como uma alternativa para avaliar pessoas cegas. Finalmente, o trabalho deixa em aberto a possibilidade de futuros desenvolvimentos e pesquisas sobre alternativas de avaliação com equidade para a população com deficiência física.

This article focuses on the importance of validity in the process of psychological evaluation, especially when the evaluation is intended for people with visual impairment, and about the development of the Computerized Adaptive Testing (CAT) as an alternative for the assessment of this population. First, a review of the main controversies about the concept of validity and the development of Computerized Adaptive Test is presented. Then, topics related to validity in CAT and scope, technological limitations, and the challenges of its use as an alternative to evaluate the visual impairment population are discussed. Finally, possibilities for future developments and research on high quality alternative assessment for populations with physical disabilities are set forth.

Cell competition promotes phenotypically silent cardiomyocyte replacement in the mammalian heart.

Heterogeneous anabolic capacity in cell populations can trigger a phenomenon known as cell competition, through which less active cells are eliminated. Cell competition has been induced experimentally in stem/precursor cell populations in insects and mammals and takes place endogenously in early mouse embryonic cells. Here, we show that cell competition can be efficiently induced in mouse cardiomyocytes by mosaic overexpression of Myc during both gestation and adult life. The expansion of the Myc-overexpressing cardiomyocyte population is driven by the elimination of wild-type cardiomyocytes. Importantly, this cardiomyocyte replacement is phenotypically silent and does not affect heart anatomy or function. These results show that the capacity for cell competition in mammals is not restricted to stem cell populations and suggest that stimulated cell competition has potential as a cardiomyocyte-replacement strategy.

Myc-driven endogenous cell competition in the early mammalian embryo.

The epiblast is the mammalian embryonic tissue that contains the pluripotent stem cells that generate the whole embryo. We have established a method for inducing functional genetic mosaics in the mouse. Using this system, here we show that induction of a mosaic imbalance of Myc expression in the epiblast provokes the expansion of cells with higher Myc levels through the apoptotic elimination of cells with lower levels, without disrupting development. In contrast, homogeneous shifts in Myc levels did not affect epiblast cell viability, indicating that the observed competition results from comparison of relative Myc levels between epiblast cells. During normal development we found that Myc levels are intrinsically heterogeneous among epiblast cells, and that endogenous cell competition refines the epiblast cell population through the elimination of cells with low relative Myc levels. These results show that natural cell competition in the early mammalian embryo contributes to the selection of the epiblast cell pool.

Effect of culture conditions and signal peptide on production of human recombinant N-acetylgalactosamine-6-sulfate sulfatase in Escherichia coli BL21.

The production and characterization of an active recombinant N-acetylgalactosamine-6-sulfate sulfatase (GALNS) in Escherichia coli BL21(DE3) has been previously reported. In this study, the effect of the signal peptide (SP), inducer concentration, process scale, and operational mode (batch and semi-continuous) on GALNS production were evaluated. When native SP was presented, higher enzyme activity levels were observed in both soluble and inclusion bodies fractions, and its removal had a significant impact on enzyme activation. At shake scale, the optimal IPTG concentrations were 0.5 and 1.5 mM for the strains with and without SP, respectively, whereas at bench scale, the highest enzyme activities were observed with 1.5 mM IPTG for both strains. Noteworthy, enzyme activity in the culture media was only detected when SP was presented and the culture was carried out under semi-continuous mode. We showed for the first time that the mechanism that in prokaryotes recognizes the SP to mediate sulfatase activation can also recognize a eukaryotic SP, favoring the activation of the enzyme, and could also favor the secretion of the recombinant protein. These results offer significant information for scaling-up the production of human sulfatases in E. coli.

Process and technoeconomic analysis of leading pretreatment technologies for lignocellulosic ethanol production using switchgrass.

Six biomass pretreatment processes to convert switchgrass to fermentable sugars and ultimately to cellulosic ethanol are compared on a consistent basis in this technoeconomic analysis. The six pretreatment processes are ammonia fiber expansion (AFEX), dilute acid (DA), lime, liquid hot water (LHW), soaking in aqueous ammonia (SAA), and sulfur dioxide-impregnated steam explosion (SO(2)). Each pretreatment process is modeled in the framework of an existing biochemical design model so that systematic variations of process-related changes are consistently captured. The pretreatment area process design and simulation are based on the research data generated within the Biomass Refining Consortium for Applied Fundamentals and Innovation (CAFI) 3 project. Overall ethanol production, total capital investment, and minimum ethanol selling price (MESP) are reported along with selected sensitivity analysis. The results show limited differentiation between the projected economic performances of the pretreatment options, except for processes that exhibit significantly lower monomer sugar and resulting ethanol yields.

Comparative study on enzymatic digestibility of switchgrass varieties and harvests processed by leading pretreatment technologies.

Feedstock quality of switchgrass for biofuel production depends on many factors such as morphological types, geographic origins, maturity, environmental and cultivation parameters, and storage. We report variability in compositions and enzymatic digestion efficiencies for three cultivars of switchgrass (Alamo, Dacotah and Shawnee), grown and harvested at different locations and seasons. Saccharification yields of switchgrass processed by different pretreatment technologies (AFEX, dilute sulfuric acid, liquid hot water, lime, and soaking in aqueous ammonia) are compared in regards to switchgrass genotypes and harvest seasons. Despite its higher cellulose content per dry mass, Dacotah switchgrass harvested after wintering consistently gave a lower saccharification yield than the other two varieties harvested in the fall. The recalcitrance of upland cultivars and over-wintered switchgrass may require more severe pretreatment conditions. We discuss the key features of different pretreatment technologies and differences in switchgrass cultivars and harvest seasons on hydrolysis performance for the applied pretreatment methods.

Selectivity and delignification kinetics for oxidative and nonoxidative lime pretreatment of poplar wood, part III: long-term.

Lime pretreatment is an effective method for improving lignocellulose digestibility by removing lignin. For several weeks, mixtures of poplar wood, water, and calcium hydroxide (lime) were submitted to temperatures from 25 to 65°C, with and without aeration. Kinetic models for lignin and carbohydrate degradation were obtained as functions of temperature, time, and aeration using first-order kinetics in lignin and carbohydrates. Model 1 considered two reacting moieties (slow and fast), and Model 2 considered three (slow, medium, and fast). Model 1 was statistically better and was employed to determine differential and integral selectivities, which measure the ability of pretreatment to retain carbohydrates while removing lignin. During the first 2 weeks, when lignin content ≥ 0.80 g/g lignin in raw biomass, both glucan and xylan differential and integral selectivities decreased rapidly. Afterwards, selectivities were nearly constant ranging between 0 and 3 g lignin removed/g carbohydrate degraded.

Effect of biodiesel glycerol type and fermentor configuration on mixed-acid fermentations.

The MixAlco process biologically converts biomass to carboxylate salts that may be converted to a variety of chemicals and fuels. This study examines the viability of different types of glycerol as a potential feedstock. Batch fermentations of crude biodiesel glycerol were compared to distilled and refined glycerol. Continuous fermentations were performed in a CSTR and a packed-bed fermentor with refined glycerol. While crude and distilled glycerol are difficult to process industrially, all types of glycerol performed well during MixAlco fermentations, producing acid concentrations above 22 g/L and conversions of greater than 65%. The CSTR configuration produced excellent acid concentrations (16 g/L) while the packed-bed configuration produced high amounts of cell material for use in cell extract products or starter cultures.

Lime pretreatment.

Lime pretreatment has proven to be a useful method for selectively reducing the lignin content of lignocellulosic biomass without significant loss in carbohydrates, thus realizing an important increase in biodigestibility. In lime pretreatment, the biomass is pretreated with calcium hydroxide and water under different conditions of temperature and pressure. It can be accomplished in one of three fashions: (1) short-term pretreatment that lasts up to 6 h, requires temperatures of 100-160 degrees C, and can be applied with or without oxygen (pressure approximately 200 psig); (2) long-term pretreatment taking up to 8 weeks, requiring only 55-65 degrees C, and capable of running with or without air (atmospheric pressure); and (3) simple pretreatment requiring 1 h in boiling water, without air or oxygen. Nonoxidative conditions are effective at low lignin contents (below approximately 18% lignin), whereas oxidative conditions are required for high lignin contents (above approximately 18% lignin).