4,752 research outputs found
Frugivory and spatial patterns of seed deposition by carnivorous mammals in anthropogenic landscapes: A multi-scale approach
Background: Knowledge about how frugivory and seed deposition are spatially distributed is valuable to understand the role of dispersers on the structure and dynamics of plant populations. This may be particularly important within anthropogenic areas, where either the patchy distribution of wild plants or the presence of cultivated fleshy-fruits may influence plant-disperser interactions. Methodology/Principal Findings: We investigated frugivory and spatial patterns of seed deposition by carnivorous mammals in anthropogenic landscapes considering two spatial scales: 'landscape' (~10 km2) and 'habitat type' (~1-2 km2). We sampled carnivore faeces and plant abundance at three contrasting habitats (chestnut woods, mosaics and scrublands), each replicated within three different landscapes. Sixty-five percent of faeces collected (n = 1077) contained seeds, among which wild and cultivated seeds appeared in similar proportions (58% and 53%) despite that cultivated fruiting plants were much less abundant. Seed deposition was spatially structured among both spatial scales being different between fruit types. Whereas the most important source of spatial variation in deposition of wild seeds was the landscape scale, it was the habitat scale for cultivated seeds. At the habitat scale, seeds of wild species were mostly deposited within mosaics while seeds of cultivated species were within chestnut woods and scrublands. Spatial concordance between seed deposition and plant abundance was found only for wild species. Conclusions/Significance: Spatial patterns of seed deposition by carnivores differed between fruit types and seemed to be modulated by the fleshy-fruited plant assemblages and the behaviour of dispersers. Our results suggest that a strong preference for cultivated fruits by carnivores may influence their spatial foraging behaviour and lower their dispersal services to wild species. However, the high amount of seeds removed within and between habitats suggests that carnivores must play an important role - often overlooked - as 'restorers' and 'habitat shapers' in anthropogenic areas.Conselleria de Educacion Xunta de Galicia PGIDIT 05RFO 20001 P
The loss of the inducible Aspergillus carbonarius MFS transporter MfsA leads to ochratoxin A overproduction
Ochratoxin A (OTA), a nephrotoxic compound produced by certain Aspergillus and Penicillium species, is one of the most abundant mycotoxins in food commodities. Aspergillus carbonarius is the main source of OTA in wine, grape juice and dried vine fruits. Although many studies have focused on OTA production by A. carbonarius, little is known about the genes related to OTA production and transport. We have found a transporter that belongs to the major facilitator superfamily (MfsA) which is highly expressed with a 102-fold induction in an ochratoxigenic A. carbonarius strain compared to a low OTA producer strain. The encoding mfsA gene shows similarity to the multidrug efflux transporter flu1 from Candida albicans. A high number of putative transcription factor binding sites involved in the response to stress were identified within the promoter of mfsA. Phenotypical analysis of δ. mfsA deletion mutants revealed that the loss of mfsA leads to a slight growth reduction and increased OTA production. We therefore hypothesize that MfsA could be a stress response transporter whose disruption could cause an increase in oxidative stress together with a stimulation of mycotoxin production. •A. carbonarius mfsA expression is induced over 100 fold in an OTA producing strain.•mfsA gene has been cloned and sequenced.•An A. carbonarius δmfsA null mutant has been obtained by ATMT.•The δmfsA null mutants produce more OTA than the parental strain.•The expression of mfsA is up regulated by hydrogen peroxide.A. Crespo-Sempere was recipient of a FPI fellowship from the Spanish Government. This research was supported by grants AGL2005-00707 and AGL2008-04828-C03-02 from the Spanish Government.Peer Reviewe
Structural and Magnetic Properties of Ni0.8Fe0.2/Ti Nanoscale Multilayers
The influence of the thickness of the Ni0.8Fe0.2 (Permalloy, Py) layers on the structural and magnetic properties of magnetron sputtered Py/Ti multilayers was studied. The thickness of the Py layers was varied in the interval of 8 to 30 angstrom. X-ray reflectivity scans evidence the existence of a well-defined layered structure in all the samples considered, but also the presence of a complex intermixed interface. The shape of both the temperature dependence of magnetization and the hysteresis loops of the multilayered structures depends strongly on Py thickness. Magnetic and reflectivity measurements were comparatively analyzed in order to better understand the structure of the samples, and specifically, their interfaces. In particular, the presence of small superparamagnetic Py at the interfaces of the samples, especially evident in the samples with the thinnest Py layers, seems confirmed by the magnetic measurements, agreeing well with the reflectivity results.The research was supported by the Ministry of Education and Science of the Russian Federation (Agreement No. 02.A03.21.0006) and by the Spanish projects MAT2014-58034-R (MINECO/AEI/FEDER, EU) and PEII-2014-042-P (JCCM/FEDER, EU)
Characterization and disruption of the cipC gene in the ochratoxigenic fungus Aspergillus carbonarius
Aspergillus carbonarius is considered the most important ochratoxin A (OTA) producing fungi among those causing OTA contamination in grapes and grape-derived products. CipC is a small protein with unknown function that was previously found to be highly up-regulated in an OTA producer strain of A. carbonarius in comparison to a non OTA producer strain. In this study, cipC was characterized and disrupted via Agrobacterium tumefaciens-mediated transformation in an ochratoxigenic A. carbonarius strain in order to study whether this gene has a role in OTA production. Sequence analysis indicated that the promoter region of cipC contains putative binding sites for transcription factors that regulate the utilization of nutrients, the stress response and detoxification processes, all factors that can influence mycotoxin biosynthesis. Although the {increment}. cipC mutant grew similarly to the wild type strain, the null mutant showed a much higher OTA production. Moreover, when A. carbonarius was grown under the oxidative stress conditions imposed by the presence of hydrogen peroxide, cipC gene expression was up-regulated. These results indicate that cipC is not directly involved in OTA biosynthesis, but sequence analysis of the A. carbonarius cipC gene promoter and the phenotype of the δ cipC disrupted mutant suggests that CipC could be a stress response protein that would be up-regulated concomitantly with OTA production. © 2013 Elsevier Ltd.A. Crespo-Sempere was recipient of a FPI fellowship from the Spanish Government. This research was supported by grants AGL2005-00707 and AGL2008-04828-C03-02 from the Spanish Government.Peer Reviewe
Modelos de control quimioterapéutico contra Fasciola hepatica en ganado bovino en pastoreo en clima cálido húmedo
2 páginas.-- Trabajo presentado al XIII Congreso Latinoamericano de ParasitologĂa ( La Habana, Cuba, 11 al 23 de Noviembre, 1997).La fasciolosis en bovinos en el estado de Veracruz, MĂ©xico, tiene una alta prevalencia, por lo que se considera una necesidad generar informaciĂłn sobre modelos de control. Con el objetivo de evaluar 3 modelos de tratamientos fasciolicidas aplicados de manera estratĂ©gica en base a las condiciones climatolĂłgicas locales, se emplearon 3 grupos de 23 vacunos cada uno, hembras cruces de cebĂş con suizo pardo, homogĂ©neos en las cantidades de huevos de 5 g de heces. Se utilizĂł el triclabendazol a dosis de 12 mg/kg. El grupo 1 fue tratado en enero, el 2 en enero y junio, y el 3 en enero, junio y octubre. Cada 45 dĂas se les practicaron exámenes coprolĂłgicos cuantitativos (hpg) por la tĂ©cnica de sedimentaciĂłn durante un año. Los bovinos se encontraban localizados en una finca situada en el municipio de Nautla, Estado de Veracruz. Se encontrĂł en el grupo 1 la prevalencia al inicio de 100%, en los siguientes 5 muestreos fue de 21.7 a 91.3 % y en el resto de 100%, mientras que el x de hpg al inicio fue de 13.23.14 se redujo en 5 muestreos de 0.560.26 a 12.12.02 mientras que en 4 se incrementĂł de 14.63.87 a 21.1 3.06 con diferencia (P0.01) entre el primer muestreo y los siguientes. En el grupo 2 la prevalencia al inicio fue de 100%, posteriormente se redujo en 8 muestreos de 8.6% a 95.6%, mientras que el Ăşltimo muestreo fue de 100%, el x de hpg al inicio fue de 15.043.62 se redujo en 8 muestreos de 0.170.13 a 14.102.13 mientras que el penĂşltimo muestreo fue de 15.733.07 con diferencia entre el primer muestreo hasta el 8, pero sin diferencia con el 9 y el 10 (P0.01). En el grupo 3 la prevalencia al inicio fue de 100% en los siguientes muestreos se redujo de 15.07% a 94.4%, mientras el x de hpg al inicio fue de 13.132.24 disminuyĂł en los subsecuentes muestreos 0.270.13 a 11.554.56 se encontrĂł que hubo diferencia entre el primer muestreo con todos los subsecuentes (P0.01). Al comparar entre grupos mediante la prueba de Kruskall-Wallis se encontrĂł que hay diferencia (P0.01) del muestreo 8 al 10.Peer reviewe
Development of a green fluorescent tagged strain of Aspergillus carbonarius to monitor fungal colonization in grapes
An enhanced green fluorescent protein has been used to tag an OTA-producing strain of Aspergillus carbonarius (W04-40) isolated from naturally infected grape berries. Transformation of the fungus was mediated by Agrobacterium tumefaciens. The most efficient transformation occurred when the co-cultivation was done with 104 conidia due to higher frequency of resistance colonies (894 per 104 conidia) and lower background obtained. To confirm the presence of the hph gene in hygromycin resistant colonies, 20 putative transformants were screened by PCR analysis. The hph gene was identified in all the transformants. Variation on the expression levels of the eGFP was detected among the transformants and 50% of them appeared bright green fluorescent under the microscope. Microscopic analysis of all the bright fluorescent transformants revealed homogeneity of the fluorescent signal, which was clearly visible in the hyphae as well as in the conidia. eGFP expression in A. carbonarius was shown to be stable in all transformants. Confocal Laser scanning microscopy images of grape berries infected with the eGFP transformant demonstrated fungal penetration into the berry tissues. OTA production was importantly increased in the eGFP transformant in comparison with the wild type strain and pathogenicity on grape berries was slightly decreased after four days of inoculation. However, no differences in virulence were found after seven days of inoculation, thus allowing utilization of this eGFP mutant for in situ analysis of A. carbonarius infection of grape berries. To our knowledge, this is the first report describing the construction of a GFP-tagged strain belonging to Aspergillus section Nigri for monitoring Aspergillus rot on grape berries.This research was supported by AGL2005-00707/ALI and AGL2008-04828-C03-02 grants from the Spanish Government.Peer Reviewe
Quantum state of the multiverse
A third quantization formalism is applied to a simplified multiverse
scenario. A well defined quantum state of the multiverse is obtained which
agrees with standard boundary condition proposals. These states are found to be
squeezed, and related to accelerating universes: they share similar properties
to those obtained previously by Grishchuk and Siderov. We also comment on
related works that have criticized the third quantization approach.Comment: 15 pages, 2 figure
Expression and characterization of the Trypanosoma cruzi dihydrofolate reductase domain
We have cloned and expressed in Escherichia coli a 702-base pair gene coding for the dihydrofolate reductase (DHFR) domain of the bifunctional dihydrofolate reductase-thymidylate synthase (DHFR-TS) from Trypanosoma cruzi. The DHFR domain was purified to homogeneity by methotrexate-Sepharose chromatography followed by an anion-exchange chromatography step in a mono Q column, and displayed a single 27-kDa band on SDS-PAGE. Gel filtration showed that the catalytic domain was expressed as a monomer. Kinetic parameters were similar to those reported for the wild-type bifunctional enzyme with Km values of 0.75 microM for dihydrofolate and 16 microM for NADPH and a kcat value of 16.5 s-1. T. cruzi DHFR is poorly inhibited by trimethoprim and pyrimethamine and the inhibition constants were always lower for the bifunctional enzyme. The binding of methotrexate was characteristic of a class of inhibitors that form an initial complex which isomerizes slowly to a tighter complex and are referred to as 'slow, tight-binding' inhibitors. While the slow-binding step of inhibition was apparently unaffected in the individually expressed DHFR domain, the overall inhibition constant was two-fold higher as a consequence of the superior inhibition constant value obtained for the initial inhibitory complex
Responsabilidad social. De la toma de decisiones a la educación del carácter: percepciones de docentes y no docentes de un establecimiento educacional chileno
La actual crisis de valores que experimenta la sociedad ha conducido al estudio de la responsabilidad social como un mĂ©todo testimonial para la educaciĂłn del carácter. Esta investigaciĂłn pretende analizar la percepciĂłn que tienen los docentes y no docentes sobre las polĂticas de responsabilidad social implementadas por una instituciĂłn de educaciĂłn en Chile. Para ello se ha utilizado un cuestionario aplicado a funcionarios de un establecimiento de nivel secundario ubicado en la regiĂłn de Ă‘uble. Finalmente, se han presentado brechas positivas y negativas entre ambos subgrupos, demostrando que los docentes presentan una percepciĂłn favorable en acciones ligadas a ciudadanĂa y participaciĂłn.The current crisis of values experienced by society has led to the study of social responsibility as a testimonial method for character education. This research aims to analyze the perception that teachers and non-teachers have of the social responsibility policies implemented by an educational institution in Chile. To do so, the questionnaire was addressed to employees of a secondary school in the Ă‘uble region. Finally, positive and negative gaps were found between the two subgroups, and showed that the teachers look favorably on actions linked to citizenship and participation
Improving Cognitive Visual-Motor Abilities in Individuals with Down Syndrome
Down syndrome causes a reduction in cognitive abilities, with visual-motor skills being
particularly affected. In this work, we have focused on this skill in order to stimulate better learning.
The proposal relies on stimulating the cognitive visual-motor skills of individuals with Down
Syndrome (DS) using exercises with a gestural interaction platform based on the KINECT sensor
named TANGO:H, the goal being to improve them. To validate the proposal, an experimental
single-case study method was designed using two groups: a control group and an experimental
one, with similar cognitive ages. Didactic exercises were provided to the experimental group using
visual cognitive stimulation. These exercises were created on the TANGO:H Designer, a platform that
was designed for gestural interaction using the KINECT sensor. As a result, TANGO:H allows for
visual-motor cognitive stimulation through the movement of hands, arms, feet and head. The “Illinois
Test of Psycholinguistic Abilities (ITPA)” was applied to both groups as a pre-test and post-test in its
four reference sections: visual comprehension, visual-motor sequential memory, visual association,
and visual integration. Two checks were made, one using the longitudinal comparison of the
pre-test/post-test of the experimental group, and another that relied on comparing the difference of the
means of the pre-test/post-test. We also used an observational methodology for the working sessions
from the experimental group. Although the statistical results do not show significant differences
between the two groups, the results of the observations exhibited an improvement in visual-motor
cognitive skills
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