6,584 research outputs found
A VACCINE PROTOTYPE USING BACULOVIRUS EXPRESSION SYSTEM FOR THE CONTROL OF AVIAN INFLUENZA VIRUS
A clade 1 sequence of H5 haemaglutinin from an Asian Avian H5N1 isolate was used as a the template to chemically synthetize a codon optimized version for expression in insect cells. A single clone was chosen for expression optimization and changes were introduced in order to maximize the amount of protein to be produced and to resemble another sequence demonstrated to be present in an isolate causing disease in Humans.
Preliminary analysis at lab scale have shown promising yields of the haemaglutinin using an activity titration assay and an ELISA-based detection method. Optimization of the cell seeding, MOI, and time of harvest have provided valuable data to ensure sufficient production of the protein compatible with scale up application.
In order to test the biological activity of the expressed protein and its ability to trigger an immune response, oil/water emulsions of different amounts of the protein were administered to SPF chickens and antibodies levels were detected using an ELISA-based system and HI titration. Both approaches were able to demonstrate seroconvertion and a dose-response curve was observed among the different doses. Altogether, results support the feasibility of the genetic contruct and the expression platform to produce bulk amounts of protein which could be used for different purposes
Growth responses of Macrocystis pyrifera (Laminariales), Southern Chile, juvenile sporophytes to nutrient limitation
1st Mares Conference on Marine Ecosystems Health and Conservation. Olhão, Portugal 17-21 November 2014.Kelp forests represent some of the most conspicuous coastal habitats and today we recognize only one giant kelp species (Macrocystis pyrifera) distributed globally [1, 2]. M. pyrifera is recognized as a perennial kelp species with a low capacity of energy storage, whereas its high productivity is associated the availability of nitrogen from the water column [3]. The relation between M. pyrifera growth and biomass production results from a plastic response of the sporophytes to temporal and spatial variability in nitrogen availability [4, 5]. However, the low storage capacity of giant kelp [6, 7] is clearly disadvantageous during periods of suboptimal environmental conditions; as those that occur seasonally in California and the inland waters of southern Chile. Due to an increased demand for kelp biomass in Chile for the world alginate industry and abalone farming in Chile [8, 9] there is an increased demand of raw material and interest for developing kelp aquaculture technologies [10].
The present study evaluates the effect of different nitrogen availability on the growth and regeneration of juvenile fronds of M. pyrifera sporophytes from southern Chile and explore its consequences for the development of seeding strategies of kelp farming in southern Chile
Paleo and historical seismicity in Mallorca (Baleares, Spain): a preliminary approach
The island of Mallorca is subject to low seismic activity. The instrumental record shows that current seismicity is surficial (La isla de Mallorca presenta una actividad sísmica baja. El registro instrumental muestra que la sismicidad actual es superficial
The RoPES project with HARPS and HARPS-N. I. A system of super-Earths orbiting the moderately active K-dwarf HD 176986
We report the discovery of a system of two super-Earths orbiting the
moderately active K-dwarf HD 176986. This work is part of the RoPES RV program
of G- and K-type stars, which combines radial velocities (RVs) from the HARPS
and HARPS-N spectrographs to search for short-period terrestrial planets. HD
176986 b and c are super-Earth planets with masses of 5.74 and 9.18
M, orbital periods of 6.49 and 16.82 days, and distances of 0.063
and 0.119 AU in orbits that are consistent with circular. The host star is a
K2.5 dwarf, and despite its modest level of chromospheric activity (log(R'hk) =
- 4.90 +- 0.04), it shows a complex activity pattern. Along with the discovery
of the planets, we study the magnetic cycle and rotation of the star. HD 176986
proves to be suitable for testing the available RV analysis technique and
further our understanding of stellar activity.Comment: 21 pages, 24 figures, 7 table
Contribution of the Residual Body in the Spatial Organization of Toxoplasma gondii Tachyzoites within the Parasitophorous Vacuole
Toxoplasma gondii proliferates and organizes within a parasitophorous vacuole in rosettes around a residual body and is surrounded by a membranous nanotubular network whose function remains unclear. Here, we characterized structure and function of the residual body in intracellular tachyzoites of the RH strain. Our data showed the residual body as a body limited by a membrane formed during proliferation of tachyzoites probably through the secretion of components and a pinching event of the membrane at the posterior end. It contributes in the intravacuolar parasite organization by the membrane connection between the tachyzoites posterior end and the residual body membrane to give place to the rosette conformation. Radial distribution of parasites in rosettes favors an efficient exteriorization. Absence of the network and presence of atypical residual bodies in a ΔGRA2-HXGPRT knock-out mutant affected the intravacuolar organization of tachyzoites and their exteriorization
A super-Earth orbiting the nearby M-dwarf GJ 536
We report the discovery of a super-Earth orbiting the star GJ 536 based on
the analysis of the radial-velocity time series from the HARPS and HARPS-N
spectrographs. GJ 536 b is a planet with a minimum mass M sin of 5.36 +-
0.69 Me with an orbital period of 8.7076 +- 0.0025 days at a distance of
0.066610(13) AU, and an orbit that is consistent with circular. The host star
is the moderately quiet M1 V star GJ 536, located at 10 pc from the Sun. We
find the presence of a second signal at 43 days that we relate to stellar
rotation after analysing the time series of Ca II H&K and H alpha spectroscopic
indicators and photometric data from the ASAS archive. We find no evidence
linking the short period signal to any activity proxy. We also tentatively
derived a stellar magnetic cycle of less than 3 years.Comment: 14 pages, 14 figures, 5 tables, Accepted in A&
Control of quality and silo storage of sunflower seeds using near infrared technology
En este trabajo se evalúa la espectroscopía de infrarrojo
cercano para su uso en el control de calidad y almacenamiento
de semillas de girasol. Los resultados indican que
el método analítico empleado puede utilizarse como método
de determinación rápida de humedad, grasa y contenidos
altos/bajos de ácido oleico. Los rangos de aplicación
son comparables con los valores que se han determinado
mediante métodos clásicos de análisis, encontrándose entre
4.6-21.4% la humedad, 38.4-49.6% la grasa y 60.0-
93.1% de ácido oleico del total de los ácidos grasos. Además
se ha utilizado un análisis discriminarte lineal por
pasos determinando las longitudes de onda más adecuadas
para la clasificación de semillas de girasol en los grupos
alto/bajo oleico. El modelo generado permitió la clasificación
de semillas de girasol en los grupos alto y bajo
oleico con unos porcentajes de muestras correctamente
clasificadas de un 90.5% en validación interna y de un
89.4% en validación cruzadaThis work assesses the application of near infrared
spectroscopy technology for the quality control of
sunflower seeds direct from farmers and from a storage
silo. The results show that the analytical method
employing near infrared spectroscopy can be used as a
rapid and non-destructive tool for the determination of
moisture, fat and high/low oleic acid contents in samples
of sunflower seeds. The ranges obtained were comparable
to those reported for classic chemical methods, and were
between 4.6-21.4% for moisture; 38.4-49.6% for fat, and
60.0-93.1% for oleic acid expressed as percentage of
total fatty acids. A stepwise discriminant analysis was
performed to determine the most useful wavelengths for
classifying sunflower seeds in terms of their (high/low)
oleic acid composition. The discriminant model allows the
classification of sunflower seeds with high or low oleicacid contents, with a prediction rate of 90.5% for internal
validation and of 89.4% for cross-validatio
Testing the chemical tagging technique with open clusters
Context. Stars are born together from giant molecular clouds and, if we
assume that the priors were chemically homogeneous and well-mixed, we expect
them to share the same chemical composition. Most of the stellar aggregates are
disrupted while orbiting the Galaxy and most of the dynamic information is
lost, thus the only possibility of reconstructing the stellar formation history
is to analyze the chemical abundances that we observe today.
Aims. The chemical tagging technique aims to recover disrupted stellar
clusters based merely on their chemical composition. We evaluate the viability
of this technique to recover co-natal stars that are no longer gravitationally
bound.
Methods. Open clusters are co-natal aggregates that have managed to survive
together. We compiled stellar spectra from 31 old and intermediate-age open
clusters, homogeneously derived atmospheric parameters, and 17 abundance
species, and applied machine learning algorithms to group the stars based on
their chemical composition. This approach allows us to evaluate the viability
and efficiency of the chemical tagging technique.
Results. We found that stars at different evolutionary stages have distinct
chemical patterns that may be due to NLTE effects, atomic diffusion, mixing,
and biases. When separating stars into dwarfs and giants, we observed that a
few open clusters show distinct chemical signatures while the majority show a
high degree of overlap. This limits the recovery of co-natal aggregates by
applying the chemical tagging technique. Nevertheless, there is room for
improvement if more elements are included and models are improved.Comment: accepted for publication in Astronomy and Astrophysics. Corrected
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