Repositorio Digital Ikiam (Univ. Regional Amazónica)
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Efectos in vitro del veneno y componentes aislados de Lachesis muta en neuroblastoma humano
Get PDFEl neuroblastoma es el cáncer sólido más común en la infancia y pese que posee terapias
dirigidas, cirugía o quimioterapia, su tratamiento no es eficaz. Es por eso que urge la
necesidad de promover la búsqueda de alternativas que mejoren o reemplacen la terapia
convencional. El veneno de las serpientes es de interés para el desarrollo de fármacos
contra el cáncer, debido a que son mezclas complejas de proteínas, enzimas y péptidos.
El objetivo de estudio es evaluar la actividad citotóxica del veneno crudo y sus
componentes mayoritarios L. muta sobre SH-SY5Y y eritrocitos humanos para contribuir
en los estudios toxinológicos de Ecuador. La citotoxicidad y la caracterización enzimática
se realizó a partir de ensayos colorimétricos MTT, RP-HPLC, electroforesis SDS-PAGE,
espectrometría de masas en tándem y espectrofotometría. La caracterización enzimática
se realizó de las fracciones más abundantes del veneno. Los resultados revelaron que 300
µg/mL de veneno tiene un 56 % de inhibición para la línea celular SH-SY5Y.
Microscópicamente, las células se redondearon y formaron agregados celulares. El
porcentaje de hemólisis fue significativamente bajo (4,54 %) respecto al control positivo.
Se tuvo cuatro fracciones de mayor abundancia relativa, donde F16 y F26 tuvieron un
significativo efecto citotóxico, disminuyendo la viabilidad celular a 83 % y 56 %,
respectivamente. La evaluación de la actividad enzimática demostró que el contenido del
veneno y las fracciones tienen actividad L-amino oxidasa, fosfolipasa, serinproteasa y
metaloproteasa. Estos hallazgos brindan la primera evidencia del efecto citotóxico en SH SY5Y de los componentes del veneno L. muta ecuatorian
Literature Circles in EFL Classrooms: The Impact on College Students in the Amazon Region from the Students' Perspective
Get PDFThis study aims to explore the effects of implementing the literature circles strategy for teaching English as a Foreign Language (EFL) in levels 2, 3, 4, 5, and 6 of a public university in the Amazon Region of Ecuador. For this purpose, three English language teachers conducted some action research. Two hundred fourteen students of English Arts made up the sample. Teachers formed groups of students in each classroom and provided them with hard copies of classic readers and free online books. Students were assigned to read one or more chapters per week and were asked to prepare for group discussions according to different roles: summarizer, predictor, connector, vocabulary manager, illustrator, and questioner. Then, the students had to present their parts and discuss the content of the chapter in groups. To analyze the impact of this strategy on students, teachers systematically collected information by using Likert scale questionnaires and interviews. Despite some challenges to be overcome, results from data collected showed that this was a positive experience that enhanced not only the students’ language abilities, but also other skills such as critical thinking, cooperative work, and autonomous learning
Can the bioturbation activity of the fiddler crab Minuca rapax modify the distribution of microplastics in sediments?
Get PDFFiddler crabs are known as "eco-engineers" who maintain habitat health through sediment bioturbation. They regularly interact with microplastics (MPs) due to their contact with the sediment. In this study we compared MPs concentration between burrows and pellets resulting from bioturbation, and MPs bioaccumulation in the soft tissues of Minuca rapax (Smith, 1870), along a gradient of urbanization in Isla del Carmen, southern Gulf of Mexico. Overall, MPs shape and color in the pellets and in the tissues reflected those of the burrow's sediments. MPs were more abundant and diverse in burrows (9 ± 12 MPs.g-1) than in pellets (5 ± 5 MPs.g-1) or in the soft tissues (1.3 ± 1.2 MPs.g-1). Bioturbation can concentrate MPs in pellets and tissues, depending on the MPs contamination and urbanization level. M. rapax is an important structuring agent of sedimentary MPs, showing a strong top-down translocation of MPs in subtropical tidal flats
The synergistic effect of microplastic and malathion exposure on fiddler crab Minuca ecuadoriensis microplastic bioaccumulation and survival
Get PDFWe assessed the combined effects of polyethylene microplastic (MP) and malathion (MLT) on the survival of the
fiddler crab Minuca ecuadoriensis, and MP tissue bioaccumulation in four treatments following 120 h exposure:
T1) Control; T2) MLT 50 mg L− 1
; T3) MP 200 mg L− 1
; and T4) MLT (50 mg L− 1
) + MP (200 mg L− 1
). The highest
mortality (80%) was in T4, followed by T2 (28%) and no mortality was in T3. Higher MP bioaccumulation was
observed in T4 (572 items g tissue− 1
) followed by T3 (70 items g tissue− 1
). Our findings indicate that the
synergistic effect of MLT and MP increased M. ecuadoriensis bioaccumulative capacity and decreases survival.
Thus, as MP contamination in aquatic environments is ubiquitous, our study raises a warning on the synergistic
effects of MP with other environmental contaminants and serves as a baseline for further studies
New insights into the decadal variability in glacier volume of a tropical ice cap, Antisana (0◦290 S, 78◦090 W), explained by the morpho-topographic and climatic contex
Get PDFAbstract. We present a comprehensive study of the evolu tion of the glaciers on the Antisana ice cap (tropical An des) over the period 1956–2016. Based on geodetic ob servations of aerial photographs and high-resolution satel lite images, we explore the effects of morpho-topographic
and climate variables on glacier volumes. Contrasting be haviour was observed over the whole period, with two pe riods of strong mass loss, 1956–1964 (−0.72 m w.e. yr−1
)
and 1979–1997 (−0.82 m w.e. yr−1
), and two periods with
slight mass loss, 1965–1978 (0.10 m w.e. yr−1
) and 1998–
2016 (−0.26 m w.e. yr−1
). There was a 42 % reduction in
the total surface area of the ice cap. Individually, glacier re sponses were modulated by morpho-topographic variables
(e.g. maximum and median altitude and surface area), par ticularly in the case of the small tongues located at low ele vations (Glacier 1, 5 and 16) which have been undergoing ac celerated disintegration since the 1990s and will likely disap pear in the coming years. Moreover, thanks to the availability
of aerial data, a surging event was detected on the Antisana
Glacier 8 (G8) in the 2009–2011 period; such an event is ex tremely rare in this region and deserves a dedicated study.
Despite the effect of the complex topography, glaciers have
reacted in agreement with changes in climate forcing, with a
stepwise transition towards warmer and alternating wet–dry
conditions since the mid s. Long-term decadal variabil-ity is consistent with the warm–cold conditions observed inthe Pacific Ocean represented by the Southern Oscillation in-de
XPS characterization of Vanadium Carbide species formed during the atomization process in Electrothermal Atomic Absorption Spectroscopy
Get PDFSolid state surface phases formed on pyrolytic graphite platforms during the atomization of vanadium in ETAAS have been characterized by means of X-ray photoelectron spectroscopy. Vanadium carbide V 8 C 7 , usually described..
Highest bush dog Speothos venaticus record for Ecuador with a potential association to a palm tree Socratea rostrata
Get PDFThe bush dog (Speothos venaticus) is one of the rarest canids in Central and South America. Very little is known about its distribution or its ecological behavior. However, there are ongoing scientific efforts to compile updated data on this species. By using line transect surveys, interviews with local people and camera traps, we studied mammals and their association with four palm-tree species (Oenocarpus bataua Socratea spp., Iriartea deltoidea, and Wettinia maynensis). Three transects, of approximately 3 kilometers each, were used to survey the piedmont of Colonso-Chalupas Biological Reserve (CCBR) in Eastern Ecuador; a recently established biological reserve (93,246 ha with an altitudinal gradient from 560 to 4432 m asl). We recorded two independent events of bush dog at 1200 m asl, using line transect surveys (one event from 91 line transect surveys) and camera trapping (two photographs from 1759 trap-nights) from September 2016 to March 2017. Both occurred at the same location, where the ground was completely covered by mature S. rostrata fruits. This is the first scientific report which confirms: the presence of bush dog in the reserve, the highest elevation of its range in Ecuador, and provides relevant data on a direct or indirect association between bush dog and a palm tree
Comparación entre los métodos EPIK y DRASTIC para evaluar la vulnerabilidad de la Formación Kárstica Napo, cuenca occidental del río Amazonas (Ecuador)
Get PDFLos ambientes kársticos son susceptibles a la contaminación, afectados directamente por presiones
antropogénicas como la minería, la extracción de petróleo y la agricultura extensiva. Los mapas de
vulnerabilidad permiten generar zonas de protección considerando que el proceso de remediación
podría ser costoso y largo. Por lo tanto, este estudio tiene como objetivo evaluar la vulnerabilidad
de la Formación Kárstica Napo utilizando índices de vulnerabilidad. Para esto se consideraron dos
índices: (i) EPIK, (ii) DRASTIC, y un DRASTIC modificado, DRASTIC-LUC.
Los resultados muestran que DRASTIC (45.76%) y EPIK (35.38%) consideran a la zona de estudio
como altamente vulnerable mientras que DRASTIC-LUC la muestra como moderadamente
vulnerable (57.47%). La diferencia entre los métodos radica en los parámetros que modelo emplea
y como calcula cada uno la vulnerabilidad. Además, es necesario considerar que la asignación de
cada parámetro está sujeta a la subjetividad porque depende del conocimiento del autor y de los
datos disponibles. El análisis de sensibilidad para evaluar la subjetividad en conjunto con el análisis
espacial muestra que DRASTIC-LUC es el mejor método que se adapta a la zona de estudio porque
el error en los datos empleados es menor e incluye un parámetro importante como la cobertura y
uso de suelo. Los resultados obtenidos pueden servir de base para futuros estudios centrados en la
validación de la metodología empleada. De igual forma, pueden incluirse en estudios técnicos para
la toma de decisiones sobre actuaciones que puedan afectar directamente a la calidad de las aguas
superficiales y subterránea
A vectorial approach to generalize the remainder theorem
Get PDFWe propose a new computational proof for the division algorithm that, usingvector algebra, generalizes the remainder theorem to divisions for polynomials of any degreeover a generic integral domain. Then, we extend this result to calculate the pseudo-divisions.Later, starting from the previous theorems, we obtain some algorithms that calculate thepseudo-remainder and the pseudo-quotient while avoiding long division. Finally, we provideexamples and comparisons indicating that these algorithms are efficient in divisions by sparsepolynomials and their divisors, as cyclotomic polynomials.2010 Mathematics Subject Classification. Primary 13B25; Secondary 13F20.Key words and phrases. polynomial pseudo-division, pseudo-remainder, algorithm, matlabcode
High rates of mercury biomagnification in fish from Amazonian floodplain-lake food webs
Get PDFDespite a global phase out of some point sources, mercury (Hg) remains elevated in aquatic food webs, posing health risks for fish-eating consumers. Many tropical regions have fast growing organisms, potentially short food chains, and few industrial point sources, suggesting low Hg baselines and low rates of trophic magnification with limited risk to people. Nevertheless, insufficient work on food-web Hg has been undertaken in the tropics and fish consumption is high in some regions. We studied Hg concentrations in fishes from floodplain lakes of the Juruá River, Amazonas, Brazil with three objectives: 1) determine rates of Hg trophic magnification, 2) assess whether Hg concentrations are high enough to impact humans eating fish, and 3) determine whether there are seasonal differences in fish Hg concentrations. A total of 377 fish-muscle samples were collected from 12 floodplain lakes during the low-water (September 2018) and falling-water (June 2019) seasons and analysed for total Hg and stable nitrogen (N) isotopes. The average trophic magnification factor (increase per trophic level) was 10.1 in the low-water season and 5.4 in the falling-water season, both well above the global average for freshwaters. This high rate of trophic magnification, coupled with higher-than-expected Hg concentrations in herbivorous species, led to high concentrations (up to 17.6 ng/g dry weight) in predatory pirarucu and piranha. Nearly 70% of all samples had Hg concentrations above the recommended human-consumption guidelines. Average concentrations were 42% higher in the low-water season than the falling-water season, but differences varied by species. Since Hg concentrations are higher than expected and fish consumption in this region is high, future research should focus on Hg exposure for human populations here and in other tropical-rainforest regions, even in the absence of local point sources of Hg