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SummaryDue to the enhanced labeling capability of maleimide-based fluorescent probes, lysine-cysteine-lysine (KCK) tags are frequently added to proteins for visualization. In this study, we employedin vitrosingle-molecule DNA flow-stretching assay as a sensitive way to assess the impact of the KCK-tag on the property of DNA-binding proteins. UsingBacillus subtilisParB as an example, we show that, although no noticeable changes were detected byin vivofluorescence imaging and chromatin immunoprecipitation (ChIP) assays, the KCK-tag substantially altered ParB’s DNA compaction rates, its response to nucleotide binding and to the presence of the specific sequence (parS) on the DNA. While it is typically assumed that short peptide tags minimally perturb protein function, our results urge researchers to carefully validate the use of tags for protein labeling. Our comprehensive analysis can be expanded and used as a guide to assess the impacts of other tags on DNA-binding proteins in single-molecule assays.MotivationSingle-molecule fluorescence microscopy has been extensively used in modern biology to define the molecular action of proteins. Appending short peptide tags is a common strategy to enhance fluorescence labeling. In this Resources article, we evaluate the impact of a commonly used tag, the lysine-cysteine-lysine (KCK) tag, on protein behavior in single-molecule DNA flow-stretching assay, which is a sensitive and versatile method to understand the action of DNA-binding proteins. Our motivation is to provide researchers with an experimental framework to validate the fluorescently labeled DNA-binding proteins in single-molecule methods.

Background: Despite long-lasting efforts to disentangle the drivers of orchid pollination, pollination success in tropical dry forest orchids remains largely unknown. Questions and hypothesis: How successful are pollination in three tropical dry forest orchids? How is pollination influenced by floral display and floral rewards (as suggested by floral micromorphology)? We hypothesized a positive effect of floral display on pollinia removal and deposition rates. Studied species: Barkeria whartoniana (C. Schweinf.) Soto Arenas, Clowesia dodsoniana E. Aguirre, and Cyrtopodium macrobulbon (La Llave & Lex.) G.A. Romero & Carnevali. Study site and dates: Nizanda (Oaxaca), Mexico; flowering periods of 2013 and 2014. Methods: We calculated pollinia removal and deposition rates, identified floral visitors and analyzed flower microstructure to search for structures potentially producing rewards. Floral display was measured through number of open flowers, and number and length of inflorescences, and its effect on pollination success was assessed through linear modeling. Results: Pollinia removal rates were higher than deposition rates, and floral display was related to pollination success in C. dodsoniana only. Visitation rates were low for the three species and most visitors were not true pollinators. The three species possess potentially secreting structures, but for B. whartoniana and C. macrobulbon these rewards are likely part of the pollinator deception mechanism. Conclusions: The generalized low pollination success implies the need for high population densities of both interacting parts. We emphasize the need for integrated evaluations of different aspects of the plant-pollinator interaction.

Chloroperoxidase (CPO) is a haeme-thiolate enzyme able to catalyse the halogenation and oxidation of a wide range of organic substrates. In this work, the CPO-catalysed chlorination and bromination reaction of natural estrogens was characterised. Estradiol, estrone and equiline were efficiently converted to halogenated compounds in the presence of chloride or bromide and hydrogen peroxide. The catalytic efficiency of CPO in this reaction is similar to that measured for other aromatic substrates; as expected the bromination reaction proceeds more efficiently than the chlorination reaction. Three major products were detected for chlorination of estradiol; two of them were monohalogenated compounds while a third product was a dihalogenated compound at positions 2 and 4 of the aromatic ring A. Chlorinated compounds are not substrates for tyrosinase, suggesting that the halogenated form of estrogens is less susceptible to form

The design and simulation of a multifunctional system for the machining of mechanical parts and printing in 3D (x, y, z) using CAD software Solid works, was used to determine the static behavior of the system with the analysis of tension, deformation, displacement, safety factor, buckling, fatigue and frequency. For the above, it was determined that the lateral base supports a tension of 3.5x108Pa, causing a displacement of 25 mm and an equivalent unit strain (ESTRN) of 0.0012. And the base guiding a cumulative damage of 300% of deterioration that reduces its useful life to a range between 1x106and 1x1065utility cycles and a safety factor (F S) between 104.632 to 7869.86. On the other hand, the transverse base has a maximum cumulative damage percentage of4.10535 and a life cycle range ranging from 24358.5 to 1x106with a minimum SF of 5974

Este estudio busca profundizar en el conocimiento de la segregación escolar por nivel socioeconómico (NSE) en Lima Metropolitana. Para ello, se estimó la magnitud de la segregación socioeconómica en las escuelas de este ámbito considerando el nivel educativo (primaria / secundaria), tipo de gestión (pública / privada), costo de pensiones (escuelas privadas) y zonificación geográfica. Se utilizó el índice socioeconómico de los estudiantes recogido en la Evaluación Censal de Estudiantes 2018. La estimación de la segregación se realizó a través del Índice de Disimilitud, del Coeficiente de Correlación Intraclase y del Índice de Aislamiento. También se categorizó a las escuelas por su condición de segregación socioeconómica. Aunque los resultados varían según el índice utilizado, en general se encontró que existe una mayor segregación socioeconómica en las escuelas primarias que en las secundarias. La segregación no es un fenómeno uniforme, pues se manifiesta de manera diferenciada según el tipo de gestión de la escuela. Si bien se registran fuertes indicios de segregación tanto en escuelas públicas como privadas, en estas últimas son mayores para ambos niveles educativos. Respecto a las zonas geográficas, los índices de segregación tienden a valores más elevados en aquellas que concentran una mayor proporción de estudiantes de NSE más alto. No obstante, los estudiantes con NSE más bajo tienen una mayor probabilidad de coincidir con pares de su mismo estatus socioeconómico que asisten a escuelas de los distritos periféricos de Lima Metropolitana. En todos los distritos analizados al menos la tercera parte de las escuelas primarias y la cuarta parte de las de secundaria se encuentran en condición de segregación.

Clenbuterol is present in animal tissues and organs and, therefore, potentially present in gelatin derived from animal sources. The objective of this study was to develop a method for identify an quantify traces of clenbuterol in gelatin and jellies. The clenbuterol calibration curve showed linearity in the range of 20–1000 pg mL−1. The detection and quantification limits were 5 pg g−1 and 10 pg g−1, respectively. The recovery of the analyte ranged from 93.4 to 98.7% with an intra-day RSD% (n = 4) of 1.25%-3.25%, and an inter-day RSD% (n = 12) of 0.5%-2.25%, with good linearity (R2 = 0.99). The method developed and validated was successfully applied in 54 gelatin samples, 57.4% of which showed clenbuterol. This UHPLC-MS/MS method combines high sensitivity with good selectivity and short chromatographic run time.

Blastose, a natural disaccharide found in honey, is usually found as a byproduct of fructo-oligosaccharide synthesis from sucrose with fructosyltransferases. In this study, we describe a novel two-step biosynthetic route to obtain blastose, designed from a detailed observation of B. subtilis levansucrase (SacB) acceptor structural requirements for fructosylation. The strategy consisted first in the synthesis of the trisaccharide O-β-d-Fruf-(2↔6)-O-α-d-Glcp-(1↔1)-α-d-Glcp, through a regioselective β-d-transfructosylation of trehalose (Tre) which acts as acceptor in a reaction catalyzed by SacB using sucrose or levan as fructosyl donor. In this reaction, levansucrase (LS) transfers regioselectively a fructosyl residue to either C6-OH group of the glucose residues in Tre. The resulting trisaccharide obtained in 23% molar yield based on trehalose, was purified and fully characterized by extensive NMR studies. In the second step, the trisaccharide is specifically hydrolyzed by trehalase, to obtain blastose in 43.2% molar yield based on the trisaccharide. This is the first report describing the formation of blastose through a sequential transfuctosylation-hydrolysis reaction.

BACKGROUND Cyclic aromatic disulfides (CAD) can be used as cross-linking agents or precursors for the synthesis of high temperature resistant polymers such as poly(phenylene disulfides) (PPD). Chemical synthesis of CAD relies on the use of corrosive agents, detrimental for the environment. This paper reports an environment friendly chemoenzymatic procedure to obtain PPD starting from simple aromatic dithiols. RESULTS The enzymatic reaction was carried out in an aqueous mixture with acetonitrile as co-solvent, using 1,4- and 1,3-benzenedithiol as monomers and a fungal laccase (EC 1.10.3.2) as catalyst. The products obtained were identified as mainly cyclic aromatic disulfides. Thermal analysis suggested that the enzymatically-synthesized CAD display thermal stability and are amenable precursors of high molecular weight sulfur-containing polymers through solvent-free, melt ring opening polymerization (mROP). After mROP, polymeric molecules around 12.8 kDa were obtained and identified as PPD. The resultant PPD shows uniform size, resistance to temperatures up to 400 °C and electrical insulating properties. CONCLUSION Laccase-catalyzed synthesis of CAD represents a novel reaction, not previously described elsewhere for oxidoreductases. A 100% substrate conversion was achieved under mild reaction conditions and no over-oxidation of CAD was observed, representing an advantage over chemical synthesis. The CAD products precipitated completely from the reaction medium, thus simplifying the purification process. © 2017 Society of Chemical Industry

[SPA] En los últimos años se ha experimentado un notable interés en los germinados de semillas por ser productos muy nutritivos y saludables, siendo incluso más ricos en compuestos beneficiosos para la salud que la planta desarrollada como es el caso de las crucíferas. El presente trabajo estudia el efecto del metil jasmonato (MJ), como elicitor químico, durante la germinación de brotes de mostaza en condiciones de ciclo de luz normal y oscuridad. Los germinados CTRL presentaron la mayor longitud de hipocótilo tanto bajo condiciones de luz (6,31 cm) como de oscuridad (9,51 cm), mientras que las diferentes concentraciones de MJ supusieron una disminución, siendo mayores bajo la condición de luz. El porcentaje de germinación en el CTRL fue del 97,3% tanto en condiciones de luz y oscuridad mientras que con MJ disminuyeron hasta valores de 93,5-95% en condición de oscuridad. Mientras, que en condiciones de luz se mantuvo constante. Según estos datos preliminares, el MJ no influyó significativamente en la productividad, siendo por tanto muy interesante su estudio como estrés abiótico para potenciar los compuestos bioactivos en futuros ensayos. [ENG] In recent years there has been a notable interest in sprouts for being very nutritious and healthy products. The sprouts are richer in bioactive compounds than the developed plant. The propose of this work was to study the effect of methyl jasmonate (MJ), as a chemical elicitor, during the germination of mustard seeds under the normal light and dark conditions. The CTRL sprouts had the longest hypocotyl length under both light (6.31) and dark (9.51 cm) conditions, while the different concentrations of MJ resulted in a decrease of the hypocotyl length, being greater under the light condition. The percentage of germination in the CTRL was 97.3% in both light and dark conditions while with MJ they tended to decrease to values of 93.5-95% in dark condition. However, the germination percentage remained constant in light conditions. According to these preliminary data, MJ did not significantly influence in the productivity, being therefore very interesting its study as abiotic stress to enhance bioactive compounds in future trials. Se agradece la financiación a la Comunidad Autónoma de la Región de Murcia a través del Programa Regional de Fomento de la Investigación Científica y Técnica de la Fundación Séneca-Agencia de Ciencia y Tecnología de la Región de Murcia (Proyecto Ref 20849/PI/18). Se agradece igualmente al Ministerio de Economía y Competitividad la concesión de un contrato predoctoral a Noelia Castillejo (FPU/04763).

Deep Eutectic Solvents (DES) were investigated as new reaction media for the synthesis of alkyl glycosides catalyzed by the thermostable α-amylase from Thermotoga maritima Amy A. The enzyme was almost completely deactivated when assayed in a series of pure DES, but as cosolvents, DES containing alcohols, sugars, and amides as hydrogen-bond donors (HBD) performed best. A choline chloride:urea based DES was further characterized for the alcoholysis reaction using methanol as a nucleophile. As a cosolvent, this DES increased the hydrolytic and alcoholytic activity of the enzyme at low methanol concentrations, even when both activities drastically dropped when methanol concentration was increased. To explain this phenomenon, variable-temperature, circular dichroism characterization of the protein was conducted, finding that above 60 °C, Amy A underwent large conformational changes not observed in aqueous medium. Thus, 60 °C was set as the temperature limit to carry out alcoholysis reactions. Higher DES contents at this temperature had a detrimental but differential effect on hydrolysis and alcoholysis reactions, thus increasing the alcoholyisis/hydrolysis ratio. To the best of our knowledge, this is the first report on the effect of DES and temperature on an enzyme in which structural studies made it possible to establish the temperature limit for a thermostable enzyme in DES.

Levan is a fructan polymer that offers a variety of applications in the chemical, health, cosmetic and food industries. Most of the levan applications depend on levan molecular weight, which in turn depends on the source of the synthesizing enzyme and/or on reaction conditions. Here we demonstrate that in the particular case of levansucrase from Bacillus subtilis 168, enzyme concentration is also a factor defining the molecular weight levan distribution. While a bimodal distribution has been reported at the usual enzyme concentrations (1 U/ml equivalent to 0.1 μM levansucrase) we found that a low molecular weight normal distribution is solely obtained al high enzyme concentrations (>5 U/ml equivalent to 0.5 μM levansucrase) while a high normal molecular weight distribution is synthesized at low enzyme doses (0.1 U/ml equivalent to 0.01 μM of levansucrase).

A new potassium permanganate–based ethylene (C2H4) scavenger was developed using sepiolite as support material. The effects of the scavenger on the main quality attributes of ‘Mirlo naranja’ apricots were evaluated in combination with modified atmosphere packaging (MAP) at 2 °C and under air packaging conditions at 15 °C. In–package gas composition, physicochemical traits (weight loss, fruit firmness, skin colour, pH, titratable acidity (TA), soluble solid content (SSC) and SSC/TA ratio, fungal incidence and sensory analysis), were monitored throughout storage. Results were compared with those obtained by using a commercial scavenger. As control, no scavengers were used. The results showed that both scavengers could achieve undetectable C2H4 concentrations within MAP packages at 2 °C. Overall, C2H4 removal resulted in a significant decrease in fruit weight loss, delayed TA decrease and led to lower SSC/TA ratio increase, while no effect was observed on fruit softening. In addition, the 15 °C–stored apricots also exhibited a lower pH increase, a decrease in C* colour parameter and less fungal incidence as a consequence of a C2H4–free environment. Furthermore, the developed scavenger reduced SSC changes of 15 °C–stored fruit, delayed fungal incidence at 2 °C, and maintained higher sensory quality during storage, maintaining good quality up to 36 d at 2 °C or 14 d at 15 °C. Accordingly, the developed C2H4 scavenger could be a good mean to delay ripening process of fresh apricots, and probably other C2H4 sensitive fruit, prolonging their postharvest storability and improving consumer acceptability.

a b s t r a c t In the present work we describe an enzymatic production method to obtain 2-6 fructose oligosaccha- rides (levan-type FOS) through a sequential reaction in which a bacterial endolevanase is applied to levan produced from sucrose by bacterial levansucrases. A putative gene encoding an endolevanase, designated as LevBl, was identified through a bioinformatics search, isolated from a strain of Bacillus licheniformis IBt1 from our own collection and expressed in Escherichia coli. LevB1 showed a specific activity of 1.8 U/mg protein at 35 ◦C in 50 mM phosphate buffer pH 6.0. A first order kinetic behavior was found when up to 150 g/L of low molecular weight levan (8.3 kDa) was used as the substrate. The product profile was determined by HPAEC-PAD and consisted of levan-type FOS with a polymerization degree between 2 and 8, with levanbiose as the major product after long reaction times. Yields of 97% of levan-type FOS were obtained when 1.0 U/mL of LevB1 reacted with 100 g/L of levan produced by the levansucrase from Bacillus subtilis. Finally, it was observed that levan-type FOS are efficiently fermented by probiotic lactic acid bacteria. © 2014 Elsevier Ltd. All rights reserved.

International audience; Levansucrases from Bacillus subtilis (BS-LVS) and Leuconostoc mesenteroides ssp. mesenteroides ATCC 8293 (LevC), inulosucrase from Leuconostoc citreum (IslA) and an invertase from Saccharomyces cerevisiae (Inv) were evaluated in acceptor reactions with non-sugar acceptors. Among them, BS-LVS was selected for the fructosylation of aromatic or aliphatic alcohols due to its high activity and stability. The effects of acceptor concentration, enzyme concentration and the presence of a co-solvent in the fructosylation efficiency of hydroquinone were evaluated. It was demonstrated that this reaction is kinetically controlled, producing the best yields of phenolic fructosides when 500 mM of acceptor and 5 U mL(-1) of enzyme were employed. Higher enzyme loads resulted in the rapid hydrolysis of the products. Increased amounts of organic co-solvent up to 50% (v/v) reduced fructoside yield due to a concomitant decrease in the thermodynamic activity of the acceptor, as confirmed by theoretical calculations using COSMO-RS; moreover, increased fructose transfer to levan and reduced hydrolysis were observed. It was found that BS-LVS preferentially fructosylates aromatic over aliphatic alcohols. A maximum fructoside production (19-35 mM) was obtained with dihydroxybenzene acceptors such as hydroquinone, whereas reactions with primary alcohols, such as benzyl alcohol resulted in lower fructosylation efficiency. This selectivity was also demonstrated by the fact that 4-hydroxybenzylalcohol, a bifunctional acceptor, was fructosylated at a rate ten times faster on its aromatic hydroxyl group. BS-LVS selectivity over phenol fructosylation was inversely correlated with the acceptor pK(a) value. (C) 2011 Elsevier B.V. All rights reserved.

The monoglucosyl-inositols a-D-glucopyranosyl-(1?4)-4D-myo-inositol 3 and a-D-glucopyranosyl(1?1)-1D-myo-inositol 4 were synthesized by a combined enzymatic transglucosylation and hydrolysis strategy, using cyclodextrin glucosyl transferase (CGTase) from Thermoanaerobacter sp., followed by hydrolysis with Aspergillus niger glucoamylase. The glucosides were separated by preparative HPLC and fully characterized by extensive 1D and 2D NMR studies. The structure of the regioisomer 4 was confirmed by X-ray crystallography of its perbenzoylated derivative 4a. Both isomers demonstrated in vivo anti-inflammatory activity at comparative levels to corticosterone on mouse ear oedema induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) and in rat hind paw oedema induced by carrageenan. 2009 Elsevier Ltd. All rights reserved.

En los debates científicos de hoy se ha generado una rigurosa y sistemática reflexión con respecto a la complejidad y su relación con el saber. Desde diferentes ópticas, se observa un debate teórico que se acercan al estudio del conocimiento complejo para la educación del futuro, localizándose entre estos, la historia. En esta disciplina de enseñanza y aprendizaje, los estudiantes deben establecer redes de conocimiento para la compresión del tejido social, muy vinculado a las concepciones del enfoque profundo de aprendizaje. Cumplir con esta finalidad en el contexto del aula, supone diseñar las estrategias de aprendizaje para enseñar a pensar históricamente.

We report the screening and characterization of EPS produced by LAB identified as Leuconostoc kimchii isolated from pulque, a traditional Mexican fermented, non-distilled alcoholic beverage produced by the fermentation of the sap extracted from several (Agave) maguey species. EPS-producing LAB constitutes an abundant bacterial group relative to total LAB present in sap and during fermentation, however, only two EPS-producing colony phenotypes (EPSA and EPSB, respectively) were detected and isolated concluding that despite the high number of polymer-producing LAB their phenotypic diversity is low. Scanning electron microcopy analysis during EPS-producing conditions revealed that both types of EPS form a uniform porous structure surrounding the bacterial cells. The structural characterization of the soluble and cell-associated EPS fractions of each polymer by enzymatic and acid hydrolysis, as by 1D- and 2D-NMR, showed that polymers produced by the soluble and cell-associated fractions of EPSA strain are dextrans consisting of a linear backbone of linked α-(1→6) Glcp in the main chain with α-(1→2) and α-(1→3)-linked branches. The polymer produced by the soluble fraction of EPSB strain was identified as a class 1 dextran with a linear backbone containing consecutive α-(1→6)-linked D-glucopyranosyl units with few α-(1→3)-linked branches, whereas the cell-associated EPS is a polymer mixture consisting of a levan composed of linear chains of (2→6)-linked β-D-fructofuranosyl residues with β-(2→6) connections, and a class 1 dextran. According to our knowledge this is the first report of dextrans and a levan including their structural characterization produced by L. kimchii isolated from a traditional fermented source.

Cyclodextrin glycosyltransferases (CGTase) are reported to selectively catalyze α(1→4)-glycosyl transfer reactions besides showing low hydrolytic activity. Here, the effect of the anomeric configuration of the glycosyl acceptor on the regioselectivity of CGTase catalyzed glycosylations was investigated. For this purpose, the α and β anomers of p-nitrophenyl- d -glucopyranoside were used as glycosyl acceptors, Bacillus macerans and Thermoanaerobacter sp. CGTases were used as biocatalysts and β-cyclodextrin as the glycosyl donor. As expected, p-nitrophenyl-α- d -glucopyranosyl-(1→4)-O-α- d -glucopyranoside was produced when p-nitrophenyl-α- d -glucopyranoside was used as acceptor with B. macerans CGTase. Surprisingly, when p-nitrophenyl-β- d -glucopyranoside was used as glycosyl acceptor, besides the expected α(1→4)-glycosylation products both α(1→3)- and α(1→6)-transfer products were also obtained. This unexpected change in B. macerans CGTase regioselectivity leading to α(1→4)-, α(1→3)- and α(1→6)-glycosylation products was also observed for Thermoanaerobacter sp. CGTase with the β anomer. It is shown, applying time course analyses, that all isomers can be synthesized efficiently by adequate selection of enzyme and reaction conditions. In fact, when using Thermoanaerobacter sp. CGTase the yield of p-nitrophenyl-β- d -isomaltoside (the α(1→6)-transfer product) was the highest at long reaction time (19% yield). The previously unknown capacity of α(1→6)-glycosidic linkages formation by CGTases demonstrates an unexpected broader regioselectivity of CGTases in glycosyl-transfer reactions as well as an acceptor dependent transfer selectivity.

FadD is an acyl coenzyme A (CoA) synthetase responsible for the activation of exogenous long-chain fatty acids (LCFA) into acyl-CoAs. Mutation of fadD in the symbiotic nitrogen-fixing bacterium Sinorhizobium meliloti promotes swarming motility and leads to defects in nodulation of alfalfa plants. In this study, we found that S. meliloti fadD mutants accumulated a mixture of free fatty acids during the stationary phase of growth. The composition of the free fatty acid pool and the results obtained after specific labeling of esterified fatty acids with a Δ5-desaturase (Δ5-Des) were in agreement with membrane phospholipids being the origin of the released fatty acids. Escherichia coli fadD mutants also accumulated free fatty acids released from membrane lipids in the stationary phase. This phenomenon did not occur in a mutant of E. coli with a deficient FadL fatty acid transporter, suggesting that the accumulation of fatty acids in fadD mutants occurs inside the cell. Our results indicate that, besides the activation of exogenous LCFA, in bacteria FadD plays a major role in the activation of endogenous fatty acids released from membrane lipids. Furthermore, expression analysis performed with S. meliloti revealed that a functional FadD is required for the upregulation of genes involved in fatty acid degradation and suggested that in the wild-type strain, the fatty acids released from membrane lipids are degraded by β-oxidation in the stationary phase of growth., This work was supported by grants from CONACyT/Mexico (49738-Q and 82614), from the Spanish MICINN(BIO2007-62988), and from Consejería de Innovación, Ciencia y Empresa (Junta de Andalucía; CVI 03541) to M.J.S. and from Laboratorio Nacional de Estructura de Macromoléculas (2006-C01-56431) to L.A. J.N. was supported by a postdoctoral contract from Consejería de Innovación, Ciencia y Empresa (Junta de Andalucía). A.P.-C. was supported during a Ph.D. program (Programa de Doctorado en Ciencias Biomédicas, Universidad Nacional Autónoma de México) by a scholarship from Consejo Nacional de Ciencia y Tecnología (Mexico).

Se reportan los resultados de un estudio documental, enmarcado en la sociología crítica de la política educativa, que indaga sobre las nivelaciones en la Educación Superior. A partir de la selección de 180 ponencias presentadas entre los últimos 9 años en la Conferencia Latinoamericana sobre el Abandono en la Educación Superior (CLABES), se indaga sobre la problematización de la equidad en la permanencia y sus procesos formativos que se movilizan en nombre de la “nivelación”. Como principales hallazgos se describe temáticamente el problema representado, desde una traducción de los estudios estadounidenses de deserción que homogeneiza las tensiones entre la propedéutica y la remediación, y entre lo curricular y lo suplementario. Más aun, con una fuerte influencia de discursos del déficit, la nivelación se presenta como un compromiso institucional con la equidad, que representa al sistema educativo como de baja calidad y a estudiantes de grupos históricamente marginados como académicamente vulnerables, por medio de metáforas de brechas y desniveles. En suma, se discute la relación entre los objetos, sujetos y lugares de nivelación, como una relación contingente, y por lo tanto, posible y necesaria de problematizar de manera diferente desde otros campos de investigación, también presentes en el espacio universitario