Colonia del Valle, Mexico

University of Tlaxcala
Colonia del Valle, Mexico
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Hernandez-Samano A.C.,Metropolitan Autonomous University | Guzman-Garcia X.,Metropolitan Autonomous University | Garcia-Barrientos R.,University of Tlaxcala | Guerrero-Legarreta I.,Metropolitan Autonomous University
Revista de Biologia Tropical | Year: 2017

Enzymatic activity of proteases from Cyprinus carpio (Cypriniformes: Cyprinidae) captured in a polluted lagoon in Mexico. Common carp (Cyprinus carpio) is an aquatic organism of commercial value able to survive in polluted environments; carps contain proteolytic enzymes of physiological importance and potential industrial application. The objective of this work was partially purify and study the proteolytic activity at different pH of carp proteases living in a polluted environment. Three carps were captured in different zones of Zumpango polluted lagoon (Mexico) at 1 m of maximum deep. Protease crude extracts were obtained from dorsal muscle by aqueous extraction and fractionated by 20 %, 50 %, 80 %-saturated (NH4)2SO4. Fractions extracted with 50 % and 80 %-saturated (NH4)2SO4 were selected for their high proteolytic activity and concentrated by ultrafiltration through 100 kDa molecular weight cutoff membranes and analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The crude proteolytic extract had significantly higher activity (19.7 - 20.3 U/mg) at pH 2, 5, and 7 (P < 0.001). Fractions obtained with 20 %, 50 % and 80 % - saturated (NH4)2SO4 showed peak activity at pH 5 (2.8 U/mg) and pH 6 (2.2 U/mg); pH 6 (4.3 U/mg) and pH 3 - 4 (3.6 - 3.7 U/mg); pH 3 (10.8 U/mg) and pH 10 (10.6 U/mg); respectively. Subfractions of < 100 kDa, obtained with 50 % and 80 %-saturated (NH4)2SO4, had peak proteolytic activity at alkaline pH. A < 100 kDa fraction, obtained with 80 %-saturated (NH4)2SO4, had the highest proteolytic activity (37.3 - 43.7 U/mg) at pH 8 - 10, purification factor of 3 and 19.1 % recovery. Thirteen proteins between 9.8 to 104.8 kDa were identified in the crude extract. Peak protein concentration was observed for 31 - 33 and 39 - 41 kDa, suggesting the possibility predominance of serine- and aspartyl- proteases, respectively. We suggest this protease with maximum activity at alkaline pH is related to the adaptation of C. carpio to polluted waters with high pH. Although unsuitable for human consumption, these organisms can be a source of protease production aimed to several uses as in the industry and waste water treatment among others. © 2017, Universidad de Costa Rica. All rights reserved.

Lopez-Juarez R.,University of Tlaxcala | Zempoalteca R.,University of Tlaxcala | Corona-Quintanilla D.L.,University of Tlaxcala | Jimenez-Estrada I.,CNR Institute of Biophysics | And 2 more authors.
Neurourology and Urodynamics | Year: 2017

Aims: To characterize the contractile properties of the bulbospongiosus (Bsm), isquiocavernosus (Ism), and pubococcygeus muscles (Pcm), and their involvement in the genesis of vaginal pressure in nulliparous and multiparous rabbits. Methods: Age-matched nulliparous and multiparous rabbits were used to record the isometric contractile responses of each muscle as well as the intravaginal pressure evoked by single square electrical pulses and stimulation trains of ascending frequency. To establish significant differences between groups, two-tail unpaired Student t tests were carried out. The linear correlation between intravaginal pressure and muscle contractile force was analyzed with Pearson correlation tests. For all cases, a P≤0.05 was set as statistically significant. Results: Multiparity decreased the contractile force of Bsm and Ism generated by high-frequency stimulation trains. The normalized force of the Pcm increased when evoked at 1, 4, and 10Hz while this decreased at higher frequencies (20, 50, and 100 Hz). The contraction of both Bsm and Ism raised particularly the pressure on the perineal vagina while that of the Pcm increased the pressure in the pelvic vagina. Such a functional segregation is still present in multiparous rabbits albeit it was modified. Conclusions: Multiparity induces changes in the contractile responses of Bsm, Ism, and Pcm, which alterates the vaginal pressure. © 2017 Wiley Periodicals, Inc.

Versiani M.A.,University of Sao Paulo | Versiani M.A.,University of Warwick | De-Deus G.,Grande Rio University | Vera J.,University of Tlaxcala | And 4 more authors.
Clinical Oral Investigations | Year: 2015

Objectives: The aim of this study was to introduce a methodology to map irrigant spreadability within the root canal space using micro-computed tomography (micro-CT).Materials and methods: Mandibular molars presenting Vertucci’s types I and II canal configurations were selected, and four scans using isotropic resolution of 19.5 μm were accomplished per tooth: prior to treatment (S1), after glide path (S2) and after root canal preparation (S3 and S4). A contrast solution (CS) was used to irrigate the canals at stages S2 and S4. The touched and untouched surface areas of the canals, the volume of irrigant-free areas and the percentage volume occupied by the CS were calculated. Density, surface tension and the spread pattern of the CS and 2.5 % NaOCl were also evaluated.Results: In the type I mesial root, there was an increase in the percentage volume of free-irrigated areas from S2 to S4 preparation steps, whilst in the distal roots and type II mesial root, a decrease of irrigant-free areas was observed. The use of CS allowed the quantification of the touched surface area and the volume of the root canal occupied by the irrigating solution. Density (g/mL) and surface tension (mN/m) of the CS and 2.5 % NaOCl were 1.39 and 47.5, and 1.03 and 56.2, respectively. Besides, a similar spread pattern of the CS and 2.5 % NaOCl in a simulated root canal environment was observed.Conclusions: This study introduced a new methodology for mapping the irrigating solution in the different stages of the root canal preparation and proved useful for in situ volumetric quantification and qualitative evaluation of irrigation spreading and irrigant-free areas.Clinical relevance: Micro-computed tomographic technology may provide a comprehensive knowledge of the flush effectiveness by different irrigants and delivery systems in order to predict the optimal cleaning and disinfection conditions of the root canal space. © 2014, Springer-Verlag Berlin Heidelberg.

Lara C.,University of Tlaxcala | Martinez-Garcia V.,University of Tlaxcala | Ornelas J.F.,Institute Ecologia
Acta Ornithologica | Year: 2015

Hummingbird vocalizations are usually displayed in two contexts. When foraging or defending territories, males and females usually display relative simple calls as territorial advertisement, while during courtship males perform individually elaborate songs to mate attraction or through singing assemblies (leks). About 15% of all described hummingbird species form leks or singing assemblies during the breeding season. However, the vocal repertoire displayed by males in these arenas has been rarely described. Here we studied the songs of Green Violetear Colibri thalassinus in a temperate forest from central Tlaxcala, Mexico, to document structure and variation within and between singing assemblies established over 3 years. We found 41 well differentiated and structurally complex syllable types across eleven recorded singing groups of Green Violetears (≈12 syllable types per singing group). The songs of most birds were repeats of the same 3-4 syllables, but the syllables types emitted can vary. Birds from the same lek tend to have similar song. Comparison of syllable sharing within-groups showed a Jaccard'similarity coefficient averaging 0.51 ± 0.09 (mean ± SD), and 0.24 ± 0.01 for among groups comparisons. These differences were corroborated by bootstrapping tests finding no significant similarity among males from different leks. However, significant similarity in syllable sharing was found between males from the same lek. No significant correlation was found between song similarity and geographic distances between leks. We have documented that static songs of lekking Green Violetears are more complex than had previously suggested. The variation of vocal repertoire among leks indicates the apparent presence of "vocal dialects" that are variable across time and space. The song variation in the context of discrimination ability in vocal neighborhoods requires further research.

Netzahuatl-Munoz A.R.,National Polytechnic Institute of Mexico | Netzahuatl-Munoz A.R.,University of Tlaxcala | Del Carmen Cristiani-Urbina M.,Autonomous University of Chiapas | Cristiani-Urbina E.,National Polytechnic Institute of Mexico
PLoS ONE | Year: 2015

The present study investigated the kinetics, equilibrium and thermodynamics of chromium (Cr) ion biosorption from Cr(VI) aqueous solutions by Cupressus lusitanica bark (CLB). CLB total Cr biosorption capacity strongly depended on operating variables such as initial Cr(VI) concentration and contact time: as these variables rose, total Cr biosorption capacity increased significantly. Total Cr biosorption rate also increased with rising solution temperature. The pseudo-second-order model described the total Cr biosorption kinetic data best. Langmuir's model fitted the experimental equilibrium biosorption data of total Cr best and predicted a maximum total Cr biosorption capacity of 305.4 mg g-1. Total Cr biosorption by CLB is an endothermic and non-spontaneous process as indicated by the thermodynamic parameters. Results from the present kinetic, equilibrium and thermodynamic studies suggest that CLB biosorbs Cr ions from Cr(VI) aqueous solutions predominantly by a chemical sorption phenomenon. Low cost, availability, renewable nature, and effective total Cr biosorption make CLB a highly attractive and efficient method to remediate Cr(VI)-contaminated water and wastewater. Copyright: © 2015 Netzahuatl-Muñoz et al.

Jimenez-Aguilar D.M.,Monterrey Institute of Technology | Ortega-Regules A.E.,University of Tlaxcala | Lozada-Ramirez J.D.,Universidad de Las Americas Puebla | Perez-Perez M.C.I.,Celaya Institute of Technology | And 2 more authors.
Journal of Food Composition and Analysis | Year: 2011

Blueberry is an important source of anthocyanins, which are highly colored substances recognized for their antioxidant activity. One of the drawbacks of using anthocyanins as food colorant is their low stability. The objective of this study was to evaluate the variations found in color and concentration of the compounds (which produce the color) on spray-dried powders, obtained from blueberry extracts with added mesquite gum. Ethanolic blueberry extracts were concentrated until reaching 35% of soluble solids. They were then spray-dried using mesquite gum as an encapsulating agent at 140 and 160 °C of air inlet temperature and 8.5, 9.1 and 9.6. mL/min of feeding rates. The lowest losses in the content of total phenolics, total anthocyanins, and color of the samples were found in samples dried at 140 °C and 9.1. mL/min. The microencapsulates that were stored for 4 weeks at 4 °C in the absence of light presented low degradation of phenolics (10%), anthocyanins (7%) and antioxidant activity (15%). Final color values were L= 39.87, C= 47.83 and H° = 28.59, with a total color difference Δ E= 5. © 2011 Elsevier Inc.

Netzahuatl-Munoz A.R.,University of Tlaxcala | Netzahuatl-Munoz A.R.,National Polytechnic Institute of Mexico | Guillen-Jimenez F.D.M.,National Polytechnic Institute of Mexico | Chavez-Gomez B.,Mexican Institute of Petroleum | And 2 more authors.
Water, Air, and Soil Pollution | Year: 2012

Solution pH is among the most important parameters that influence heavy metal biosorption. This work presents a kinetic study of the effects of pH on chromium biosorption onto Cupressus lusitanica Mill bark from aqueous Cr(VI) or Cr(III) solutions and proposes a mechanism of adsorption. At all assayed contact times, the optimum pH for chromium biosorption from the Cr(III) solution was 5.0; in contrast, optimum pH for chromium biosorption from the Cr(VI) solution varied depending on contact time. The kinetic models that satisfactorily described the chromium biosorption processes from the Cr(III) and Cr (VI) solutions were the Elovich and pseudo second-order models, respectively. Diffuse reflectance infrared Fourier transform spectroscopy studies suggest that phenolic compounds present on C. lusitanica Mill bark play an important role in chromium biosorption from the Cr(III) solution. On the other hand, chromium biosorption from the Cr(VI) solution involved carboxyl groups produced on the bark by redox reactions between oxygen-containing groups and Cr(VI), and these were in turn responsible for the biosorption of Cr (III) produced by Cr(VI) reduction. © Springer Science+Business Media B.V. 2011.

Castro-Ramirez J.,University of Tlaxcala | Martinez-Guerra R.,CINVESTAV | Cruz-Victoria J.C.,University of Tlaxcala
Chaos | Year: 2015

This paper deals with the master-slave synchronization scheme for partially known nonlinear chaotic systems, where the unknown dynamics is considered as the master system and we propose the slave system structure which estimates the unknown states. It introduced a new reduced order observer, using the concept of Algebraic Observability; we applied the results to a Sundarapandian chaotic system, and by means of some numerical simulations we show the effectiveness of the suggested approach. Finally, the proposed observer is utilized for encryption, where encryption key is the master system and decryption key is the slave system. © 2015 AIP Publishing LLC.

Lado C.,Real Jardin Botanico de Madrid | Wrigley De Basanta D.,Real Jardin Botanico de Madrid | Estrada-Torres A.,University of Tlaxcala | Stephenson S.L.,University of Arkansas
Fungal Diversity | Year: 2013

The results obtained from two expeditions to survey the biodiversity of myxomycetes in Central Chile are reported in this paper. The surveys were carried out as part of Global Biodiversity of Eumycetozoans project funded by the National Science Foundation (USA) and the Myxotropic project funded by the Spanish Government. The expeditions were made to the temperate zone of the central part of the country between 23 and 39 South latitudes, which is characterized by Mediterranean vegetation, as well as to the transition areas between the arid and semi-arid regions of northern Chile, and the humid, cold Valdivian and Andean-Patagonian forests of the far South. Eight of the fifteen regions of the country, from Antofagasta to Araucanía, in selected areas where the native vegetation is well preserved, were included in these surveys. Over 600 collections were obtained, and a total of 110 species of myxomycetes representing 29 genera have been identified. Two of these (Dianema succulenticola, Didymium chilense) are species new to science and are described in this paper, 12 species (Collaria nigricapillitia, Comatricha alta, Cribraria oregana, Dianema depressum, Didymium eximium, D. nivicolum, Enerthenema melanospermum, Lepidoderma chailletii, Macbrideola ovoidea, Physarum clavisporum, Ph. newtonii and Trichia alpina) were previously unknown for either the Neotropics or South America, and 49 additional species are new records for Chile. Comments are provided on the morphology, distribution and ecology of selected species and light and SEM micrographs of the most significant species are included. An evaluation of the biodiversity of myxomycetes in Chile, with special emphasis on the endemic plants that provided the substrates with which they were associated, and a comparative analysis of our results with those from other countries of South America is presented. © 2012 The Mushroom Research Foundation.

PubMed | University of Tlaxcala, Metropolitan Autonomous University, UPAEP University and Autonomous University of Tlaxcala
Type: | Journal: The Science of the total environment | Year: 2016

Di(2-ethylhexyl) phthalate (DEHP) is a plasticizer widely used in the manufacture of plastics, and it is an environmental contaminant. The specific growth rate (), maximum biomass (Xmax), biodegradation constant of DEHP (k), half-life (t1/2) of DEHP biodegradation and removal efficiency of DEHP, esterase and laccase specific activities, and enzymatic yield parameters were evaluated for Fusarium culmorum grown on media containing glucose and different concentrations of DEHP (0, 500 and 1000mg/L). The greatest and the largest Xmax occurred in media supplemented with 1000mg of DEHP/L. F. culmorum degraded 95% of the highest amount of DEHP tested (1000mg/L) within 60h of growth. The k and t1/2 were 0.024h(-1) and 28h, respectively, for both DEHP concentrations. The removal efficiency of DEHP was 99.8% and 99.9% for 1000 and 500mg/L, respectively. Much higher specific esterase activity than specific laccase activity was observed in all media tested. The compounds of biodegradation of DEHP were identified by GC-MS. A DEHP biodegradation pathway by F. culmorum was proposed on the basis of the intermolecular flow of electrons of the identified intermediate compounds using quantum chemical modeling. DEHP was fully metabolized by F. culmorum with butanediol as the final product. This fungus offers great potential in bioremediation of environments polluted with DEHP.

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