2,140 research outputs found
Free-living ciliates from a perturbed marsh in Central Mexico: some notes about taxonomy and ecology
En éste artículo se da a conocer el primer inventario de Ciliados en el lago Atarasquillo una de las Cíenegas del Lerma. México.Ciliates are a morphologically diverse group of eukaryotes inhabiting aquatic and terrestrial ecosystems. We studied the taxonomy and ecology of free-living ciliates from a freshwater marsh in Central Mexico during the period from 2012 to 2013 during both dry and rainy seasons. We found 30 ciliate species recorded for the first time from Atarasquillo marsh in Mexico, most of which are common species in freshwater ecosystems. The species richness was higher during the dry season than rainy season. Five trophic groups were observed: bacterivorous, bacteria-algae-heterotrophic flagellate consumers (BAF-consumers), omnivorous, predators, and myxotrophic species. The trophic group composition changed according of the season and the environmental conditions, e.g. vegetation and water level. Generally bacterivorous ciliates were more frequent during the rainy season, meanwhile the omnivorous were during the dry season, thus the feeding strategies in ciliates are different between both seasons. Due to the fact that Atarasquillo marsh is in deterioration process, ciliate records could be used to assess water quality.Secretaría de Investigación, UAEM. Proyecto de Investigación: 3429/2013 CHT
In vitro Study of the Survival, Reproduction and Morphology of Daphnia pulicaria irradiated with a Low Energy Laser
Articulo científico en open accesDaphnia is a genus of crustaceans that is representative of freshwater communities. The species exhibit a high sensitivity to a wide range of toxic compounds so that they have been used internationally as biomonitors in toxicity tests to evaluate ecosystem conditions such as water quality. It is also a model genus in genetics, epigenetics and reproductive ecology. In this work, we used Daphnia pulicaria as a model to measure the effects of low-energy laser irradiation on survival, reproduction, and morphology variables of parental organisms and their offspring. We used (1) a single clone line of organisms to eliminate interindividual genetic variability; (2) individuals from more than 50 generations after the clone line was established, and offspring from the third brood onwards to dissipate maternal and epigenetic effects, and (3) neonates, those individuals of the species that have less than 48 hours of life, because they are the most sensitive stage to optical stimuli. We analyzed number of deaths, longevity, age at first reproduction, number of offspring per week, number of total offspring during all their life cycle, body size, size of the antennules, and length of the apical spine of the 4th and 5th brood of the irradiated individuals, who were exposed to a blue laser stimulus of 405 nm for 25 minutes with a power of 40 mW at a distance of 50 cm, compared to those of the control (non-irradiated) group
(Serie: Conservación y Manejo de Áreas Naturales Protegidas del Altiplano Mexicano)
El Programa de Manejo del Área Natural Protegida Parque Estatal Otomí – Mexica es un instrumento de planeación incluyente, dinámico, flexible y congruente con lo que establece el Código para la Biodiversidad del Estado de México (CBEM) y la Ley General del Equilibrio Ecológico y la Protección al Ambiente (LGEEPA), teniendo como propósito cumplir con los objetivos de su decreto.El Programa de Manejo del Área Natural Protegida Parque Estatal Otomí – Mexica es un instrumento de planeación incluyente, dinámico, flexible y congruente con lo que establece el Código para la Biodiversidad del Estado de México (CBEM) y la Ley General del Equilibrio Ecológico y la Protección al Ambiente (LGEEPA), teniendo como propósito cumplir con los objetivos de su decreto.Gobierno del Estado de México Universidad Autónoma del Estado de México Colegio de Ciencias Geográficas del Estado de México, A. C
Composición de leche caprina de área serrana y llana
El objetivo del presente trabajo fue medir y comparar grasa, proteína y sólidos totales de leche caprina de establecimientos de los llanos y de las sierras del sur de La Rioja.EEA La RiojaFil: Mendez, Carla Rebeca. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria La Rioja. Agencia de Extensión Rural Chepes; ArgentinaFil: Cabral Ortiz, Daniel Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Centro Regional Catamarca - La Rioja; ArgentinaFil: Chavez, Mónica Esther. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Salta; ArgentinaFil: Orosco, Silvia Marisol. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Salta; ArgentinaFil: Sanchez Allendes, Maria Virginia. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Salta; Argentin
Study protocol and rationale of the “Cogniaction project” a cross-sectional and randomized controlled trial about physical activity, brain health, cognition, and educational achievement in schoolchildren
Background: Education and health are crucial topics for public policies as both largely determine the future
wellbeing of the society. Currently, several studies recognize that physical activity (PA) benefits brain health
in children. However, most of these studies have not been carried out in developing countries or lack the
transference into the education field. The Cogni-Action Project is divided into two stages, a cross-sectional
study and a crossover-randomized trial. The aim of the first part is to establish the associations of PA,
sedentarism, and physical fitness with brain structure and function, cognitive performance and academic
achievement in Chilean schoolchildren (10–13 years-old). The aim of the second part is to determinate the
acute effects of three PA protocols on neuroelectric indices during a working memory and a reading task.
Methods: PA and sedentarism will be self-reported and objectively-assessed with accelerometers in a representative
subsample, whilst physical fitness will be evaluated through the ALPHA fitness test battery. Brain structure and function
will be assessed by magnetic resonance imaging (MRI) in a randomized subsample. Cognitive performance will be
assessed through the NeuroCognitive Performance Test, and academic achievement by school grades. In the second part
32 adolescents (12–13 year-old) will be cross-over randomized to these condition (i) “Moderate-Intensity Continuous
Training” (MICT), (ii) “Cooperative High-Intensity Interval Training” (C-HIIT), and (iii) Sedentary condition. Neuroelectric
indices will be measures by electroencephalogram (EEG) and eye-tracking, working memory by n-back task and reading
comprehension by a reading task
Single step syntheses of (1 S)-aryltetrahydroisoquinolines by norcoclaurine synthases
The 1-aryl-tetrahydroisoquinoline (1-aryl-THIQ) moiety is found in many biologically active
molecules. Single enantiomer chemical syntheses are challenging and although some biocatalytic
routes have been reported, the substrate scope is limited to certain structural motifs.
The enzyme norcoclaurine synthase (NCS), involved in plant alkaloid biosynthesis, has been
shown to perform stereoselective Pictet–Spengler reactions between dopamine and several
carbonyl substrates. Here, benzaldehydes are explored as substrates and found to be
accepted by both wild-type and mutant constructs of NCS. In particular, the variant M97V
gives a range of (1 S)-aryl-THIQs in high yields (48–99%) and e.e.s (79–95%). A cocrystallised
structure of the M97V variant with an active site reaction intermediate analogue
is also obtained with the ligand in a pre-cyclisation conformation, consistent with (1 S)-THIQs
formation. Selected THIQs are then used with catechol O-methyltransferases with exceptional
regioselectivity. This work demonstrates valuable biocatalytic approaches to a range of
(1 S)-THIQ
Vitamin C supplement use may protect against gallstones: an observational study on a randomly selected population
<p>Abstract</p> <p>Background</p> <p>Animal experiments have shown a protective effect of vitamin C on the formation of gallstones. Few data in humans suggest an association between reduced vitamin C intake and increased prevalence of gallstone disease. The aim of this study was to assess the possible association of regular vitamin C supplementation with gallstone prevalence.</p> <p>Methods</p> <p>An observational, population-based study of 2129 subjects aged 18-65 years randomly selected from the general population in southern Germany was conducted. Abdominal ultrasound examination, completion of a standardized questionnaire, compilation of anthropometric data and blood tests were used. Data were collected in November and December 2002. Data analysis was conducted between December 2005 and January 2006.</p> <p>Results</p> <p>Prevalence of gallstones in the study population was 7.8% (167/2129). Subjects reporting vitamin C supplementation showed a prevalence of 4.7% (11/232), whereas in subjects not reporting regular vitamin C supplementation, the prevalence was 8.2% (156/1897). Female gender, hereditary predisposition, increasing age and body-mass index (BMI) were associated with increased prevalence of gallstones. Logistic regression with backward elimination adjusted for these factors showed reduced gallstone prevalence for vitamin C supplementation (odds ratio, OR 0.34; 95% confidence interval, CI 0.14 to 0.81; P = 0.01), increased physical activity (OR 0.62; 95% CI, 0.42 to 0.94; P = 0.02), and higher total cholesterol (OR 0.65; 95% CI, 0.52 to 0.79; P < 0.001).</p> <p>Conclusion</p> <p>Regular vitamin C supplementation and, to a lesser extent, increased physical activity and total cholesterol levels are associated with a reduced prevalence of gallstones. Regular vitamin C supplementation might exert a protective effect on the development of gallstones.</p
Performance of the CMS Cathode Strip Chambers with Cosmic Rays
The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device
in the CMS endcaps. Their performance has been evaluated using data taken
during a cosmic ray run in fall 2008. Measured noise levels are low, with the
number of noisy channels well below 1%. Coordinate resolution was measured for
all types of chambers, and fall in the range 47 microns to 243 microns. The
efficiencies for local charged track triggers, for hit and for segments
reconstruction were measured, and are above 99%. The timing resolution per
layer is approximately 5 ns
Search for supersymmetry in events with b-quark jets and missing transverse energy in pp collisions at 7 TeV
Results are presented from a search for physics beyond the standard model
based on events with large missing transverse energy, at least three jets, and
at least one, two, or three b-quark jets. The study is performed using a sample
of proton-proton collision data collected at sqrt(s) = 7 TeV with the CMS
detector at the LHC in 2011. The integrated luminosity of the sample is 4.98
inverse femtobarns. The observed number of events is found to be consistent
with the standard model expectation, which is evaluated using control samples
in the data. The results are used to constrain cross sections for the
production of supersymmetric particles decaying to b-quark-enriched final
states in the context of simplified model spectra.Comment: Submitted to Physical Review
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