Mutational Analysis of the Conserved Cysteine Residues in the Simian Immunodeficiency Virus Matrix Protein

AbstractThe matrix protein (MA) of human and simian immunodeficiency viruses (HIV and SIV) is encoded by the amino-terminal region of the Gag precursor and has been suggested to be involved in different processes during the early and rate stages of the virus life cycle. The MA protein of SIV contains three cysteine residues at positions 57, 83, and B7, which are also highly conserved among HIV-2 isolates. In order to study the functional significance of these residues in virus morphogenesis, a series of mutations affecting the cysteines of SIV MA were introduced into a gag-protease construct and expressed in the vaccinia vector system. The MA mutants were assayed for their ability to synthesize and process the Gag polyprotein precursor as well as to release particles into the culture medium. In addition, the incorporation of the envelope glycoprotein (Env) into the Gag-made particles was investigated. Substitution of alanine for cysteine 87 had little effect on particle release and Env glycoprotein association. By contrast, the individual replacement of cysteines 57 or 83 by alanine, as well as the simultaneous mutation of cysteines 83 and 87, significantly reduced the ability of Gag polypeptides to produce extracellular particles. Assembly into particles appeared to be also affected, albeit to a lesser extent, when both cysteines 57 and 83 were replaced by alanine. Furthermore, substitution of cysteine 83 in the SIV MA domain was found to be detrimental to Gag polyprotein processing. Analysis of the Env glycoprotein association with recombinant particles revealed that this process was moderately affected in the case of the double mutants lacking cysteines 57 and 83, or cysteines 57 and 87, and the cysteine-minus triple mutant. Our results suggest that the Conserved cysteines 57 and 83 in the MA domain are important for efficient SIV Gag particle production

Integration of biophysical connectivity in the spatial optimization of coastal ecosystem services

Ecological connectivity in coastal oceanic waters is mediated by dispersion of the early life stages of marine organisms and conditions the structure of biological communities and the provision of ecosystem services. Integrated management strategies aimed at ensuring long-term service provision to society do not currently consider the importance of dispersal and larval connectivity. A spatial optimization model is introduced to maximise the potential provision of ecosystem services in coastal areas by accounting for the role of dispersal and larval connectivity. The approach combines a validated coastal circulation model that reproduces realistic patterns of larval transport along the coast, which ultimately conditions the biological connectivity and productivity of an area, with additional spatial layers describing potential ecosystem services. The spatial optimization exercise was tested along the coast of Central Chile, a highly productive area dominated by the Humboldt Current. Results show it is unnecessary to relocate existing management areas, as increasing no-take areas by 10% could maximise ecosystem service provision, while improving the spatial representativeness of protected areas and minimizing social conflicts. The location of protected areas was underrepresented in some sections of the study domain, principally due to the restriction of the model to rocky subtidal habitats. Future model developments should encompass the diversity of coastal ecosystems and human activities to inform integrative spatial management. Nevertheless, the spatial optimization model is innovative not only for its integrated ecosystem perspective, but also because it demonstrates that it is possible to incorporate time-varying biophysical connectivity within the optimization problem, thereby linking the dynamics of exploited populations produced by the spatial management regime.Comment: 30 pages, 5 figures, 2 tables; 1 graphical abstract. In this version: numbering of figures corrected, updated figure 2, typos corrected and references fixe

CRECIMIENTO Y CONTENIDO TOTAL DE CAROTENOIDES EN CUATRO CEPAS CHILENAS DE HAEMATOCOCCUS PLUVIALIS FLOTOW, BAJO CONDICIONES DE LABORATORIO

Haematococcus pluvialis is a unicellular green microalga cultivated on a large scale as a natural source of astaxanthin, aketocarotenoid of high commercial value due to its colorant and antioxidant properties. The aim of this study was tocompare growth and total carotenoids among four strains of H. pluvialis isolated from different microhabitats in twogeographical locations in Chile. Growth was carried out under autotrophic and mixotrophic conditions and under twophoton flux densities (PFD) (20 and 85 µmol m-2s -1). Total carotenoid content was estimated on day 45. Most of thestrains grew better under the autotrophic conditions; the highest exponential growth rates were exhibited at the high PFDin all the strains (ranging from 0.73 to 1.20 div day-1) with the exception of CCM-UDEC 023 which showed the sameexponential growth rate with either PFD (0.73 div day-1). However, the cell density estimated on day 14 was higher at thelow PFD in CCM-UDEC 022 and CCM-UDEC 023 (4.4 x 105 and 8.9 x 104 cells ml-1, respectively). The mixotrophiccondition slightly improved the growth rate of the strain CCM-UDEC 021 at the high PFD (from 1.04 div day-1 atautotrophic condition to 1.25 and 1.14 div day-1 at 2mMand 10mM sodium acetate, respectively). The algal dry weightestimated on day 14 was not significantly correlated with the cell density, but it was, to a certain extent, related to theproportion and size of the different cell types quantified on that day. The strain with the highest dry weight at the endof the experimental period and under all the assayed conditions was CCM-UDEC 023. It was also the strain thatproduced the highest total carotenoid content under both autotrophic (5.6 mg l-1 and 95.6 pg cell-1 at the high PFD) andmixotrophic (with 2mM acetate) conditions (10.8 mg l-1 and 297 pg cell-1 at the high PFD). A high intraspecific variabilityin the physiological attributes analyzed existed among the strains under study. Even though the mixotrophic conditionassayed did not substantially improve the growth rate of any strain, it did improve the total carotenoid yield in the strainCCM-UDEC 023.Haematococcus pluvialis es una microalga unicelular verde cultivada masivamente como fuente natural de astaxantina,un cetocarotenoide de alto valor comercial debido a sus propiedades como colorante y antioxidante. El objetivo de esteestudio fue comparar el crecimiento y el contenido de carotenoides totales en 4 cepas de H. pluvialis aisladas dediferentes microhabitats de dos regiones geográficas de Chile. El crecimiento se llevó a cabo en condiciones autotróficasy mixotróficas a dos densidades de flujo fotónico (DFF) (20 y 85 µmol m-2s -1). El contenido de carotenoides totales seestimó el día 45. La mayoría de las cepas crecieron mejor en condiciones autotróficas; las más altas tasas de crecimientoexponencial se presentaron a la mayor DFF en todas las cepas (fluctuó entre 0,73 y 1,20 div día-1) a excepción de lacepa CCM-UDEC 023 la cual mostró la misma tasa de crecimiento exponencial a cualquier DFF (0,73 div día-1). Sinembargo, la densidad celular estimada el día 14 fue mayor a la menor DFF en CCM-UDEC 022 y CCM-UDEC 023(4,4 x 105 y 8,9 x 104 céls ml-1, respectivamente). La condición mixotrófica mejoró levemente la tasa de crecimiento dela cepa CCM-UDEC 021 a la mayor DFF (de 1,04 div día-1 en condición autotrófica a 1,25 y 1,14 div día-1 a 2mM y10mM de acetato de sodio, respectivamente). El peso seco algal estimado el día 14 no mostró correlación significativa con la densidad celular, pero sí, en un cierto sentido, con la proporción y el tamaño de los diferentes tipos celulares a esedía. La cepa que presentó el mayor peso seco al final del periodo experimental y bajo todas las condiciones ensayadas fueCCM-UDEC 023. Esta fue también la cepa que produjo la cantidad de carotenoides totales más alta, tanto en condicionesautotróficas (5,6 mg l-1 y 95,6 pg cél-1 a la mayor DFF) como mixotróficas (con 2mM acetato) (10,8 mg l-1 y 297 pg cél-1 a lamayor DFF). Las cepas en estudio presentaron una alta variabilidad intraespecífica en los atributos fisiológicos analizados.Aún cuando las condiciones mixotróficas ensayadas no aumentaron sustancialmente las tasas de crecimiento de alguna de lascepas (CCM-UDEC 020, CCM-UDEC 022), esta condición sí mejoró la producción de carotenoides totales en la cepaCCM-UDEC 023

Functional relationship between the matrix proteins of feline and simian immunodeficiency viruses

AbstractTo investigate the functional relationship between the matrix (MA) proteins of feline and simian immunodeficiency viruses (FIV and SIV, respectively), we generated chimeric proviruses in which the MA-coding region of an SIV infectious molecular clone was partially or fully replaced by its FIV counterpart. Chimeric SIV proviruses containing the amino-terminal 36 residues or the central and carboxy-terminal regions of the FIV MA assembled into virions as efficiently as wild-type SIV. However, the resulting virions were noninfectious in single-cycle infectivity assays. Furthermore, a chimeric SIV provirus containing the entire FIV MA was found to be severely impaired in virion production due to inefficient membrane binding of the chimeric Gag polyprotein. Interestingly, the assembly defective phenotype of this chimeric Gag precursor could be reversed either by introducing the G31K/G33K double amino acid substitution in the FIV-derived MA domain or by coexpression with wild-type SIV Gag. Of note, a chimeric FIV provirus expressing the SIV MA not only assembled into particles as efficiently as wild-type FIV, but also replicated in feline T cells with wild-type kinetics. Our results thus provide novel information about the functional homology between the MA proteins of distantly related lentiviruses

Spitzer-IRS high resolution spectroscopy of the 12\mu m Seyfert galaxies: I. First results

The first high resolution Spitzer IRS 9-37um spectra of 29 Seyfert galaxies (about one quarter) of the 12um Active Galaxy Sample are presented and discussed. The high resolution spectroscopy was obtained with corresponding off-source observations. This allows excellent background subtraction, so that the continuum levels and strengths of weak emission lines are accurately measured. The result is several new combinations of emission line ratios, line/continuum and continuum/continuum ratios that turn out to be effective diagnostics of the strength of the AGN component in the IR emission of these galaxies. The line ratios [NeV]/[NeII], [OIV]/[NeII], already known, but also [NeIII]/[NeII] and [NeV]/[SiII] can all be effectively used to measure the dominance of the AGN. We extend the analysis, already done using the 6.2um PAH emission feature, to the equivalent width of the 11.25um PAH feature, which also anti-correlates with the dominance of the AGN. We measure that the 11.25um PAH feature has a constant ratio with the H_2 S(1) irrespective of Seyfert type, approximately 10 to 1. Using the ratio of accurate flux measurements at about 19um with the two spectrometer channels, having aperture areas differing by a factor 4, we measured the source extendness and correlated it with the emission line and PAH feature equivalent widths. The extendness of the source gives another measure of the AGN dominance and correlates both with the EWs of [NeII] and PAH emission. Using the rotational transitions of H$_2$ we were able to estimate temperatures (200-300K) and masses (1-10 x 10^6 M_sun), or significant limits on them, for the warm molecular component in the galaxies observed.Comment: submitted to ApJ, Aug.2007, revised, in the refereeing proces

Dimensionality reduction in images for appearance-based camera localization

[Abstract] Appearance-based Localization (AL) focuses on estimating the pose of a camera from the information encoded in an image, treated holistically. However, the high-dimensionality of images makes this estimation intractable and some technique of dimensionality Reduction (DR) must be applied. The resulting reduced image representation, though, must keep underlying information about the structure of the scene to be able to infer the camera pose. This work explores the problem of DR in the context of AL, and evaluates four popular methods in two simple cases on a synthetic environment: two linear (PCA and MDS) and two non-linear, also known as Manifold Learning methods (LLE and Isomap). The evaluation is carried out in terms of their capability to generate lower-dimensional embeddings that maintain underlying information that is isometric to the camera poses.Junta de Andalucía; P20 0130

Cambios nictemerales en la distribución vertical de algunos microcrustáceos en un lago artificial del neotrópico (Colombia)

En el Lago Acuarela, un sistema artificial de poca profundidad, se analizó la distribución vertical diaria de los microcrustáceos planctónicos y su relación con algunas variables físicas y químicas. Se evaluaron cuatro ciclos nictemerales a intervalos de tres horas en el sitio más profundo del lago. El cuerpo de agua presentó: Inestabilidad térmica en casi todos los horarios de octubre, enero y mayo, estratificación física y química permanente en todo el nictemeral de marzo y estratificación óxica en todos los muestreos, con anóxia en el fondo. Bosmina longirostris (Cladocera) fue la especie más abundante, seguida de los nauplios (Copepoda) que presentaron mayor densidad que los adultos de Arctodiaptomus dorsalis y Thermocyclops decipiens (Copepoda). Las tres especies y los nauplios presentaron diferencias significativas de la densidad entre los ciclos y en su distribución vertical para cada muestreo, pero no se hallaron diferencias significativas entre horarios, por lo que posiblemente predominó la migración horizontal sobre la migración vertical. Los microcrustáceos se ubicaron principalmente en capas eufóticas y frecuentemente se agregaron en la columna de agua como un gremio más que como poblaciones aisladas, excepto en algunas ocasiones T. decipiens.The diel vertical distribution of the planktonic microcrustacean and its relationship with some physical and chemical variables was analyzed in the Lake Acuarela, a little depth artificial system. Four nictemeral cycles were evaluated at intervals of three hours in the deepest place of the lake. The water body had: Thermal instability in almost every hour of October, January and May, permanent physical and chemical stratification in the whole nictemeral of March and oxic stratification in all the samplings, with an anoxic bottom. Bosmina longirostris (Cladocera) was the most abundant species followed by the nauplios (Copepoda) that had a higher density than the adults of Arctodiaptomus dorsalis and Thermocyclops decipiens (Copepoda). Those three species and the nauplios had significant differences of density among the cycles and in their vertical distribution for each sampling, but there were not significant differences among hours, this could means that the horizontal migration possibly prevailed on the vertical migration. The microcrustaceans were located mainly in euphotic layers and frequently they were aggregated in the water column like a guilt more than like isolated populations, except in some occasions T. decipiens

Structural and Vibrational Properties and NMR Characterization of (2’-furyl)-Imidazole Compounds

The furylimidazoles compounds have a great importance in biochemistry and pharmacology because many of them present interesting properties. They are also found in artificial compounds, such as agrochemicals, pharmaceuticals, dyes, plastics, solvents, photographic chemicals, electronics, corrosion inhibitors, preservatives, and polymers. They can be used in synthetic organic chemistry as building blocks, due to their presence as key structural units in many natural products and in important pharmaceuticals. For example, the nature of the N- atoms in the imidazole molecule makes possible an extraordinary variety of reactions and this is the main reason for the great biological importance of the amino acid, histidine.Fil: Ledesma, Ana Estela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Química del Noroeste. Grupo Vinculado Unse-inquinoa; ArgentinaFil: Zinczuk, Juan. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: López González, Juan J.. Universidad de Jaén; EspañaFil: Brandan, Silvia Antonia. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Inorgánica. Cátedra de Química General.; Argentin

Critical thinking: the ARDESOS-DIAPROVE programme in dialogue with the Inference to the Best and Only explanation

[EN]In our daily lives, we are often faced with the need to explain various phenomena, but we do not always select the most accurate explanation. For example, let us consider a “toxic” relationship with physical and psychological abuse, where one of the partners is reluctant to end it. Explanations for this situation can range from emotional or economic dependency to irrational hypotheses such as witchcraft. Surprisingly, some people may turn to the latter explanation and consequently seek ineffective solutions, such as visiting a witch doctor instead of a psychologist. This choice of an inappropriate explanation can lead to actions that are not only ineffective but potentially harmful. This example underscores the importance of inference to the best explanation (IBE) in everyday decision making. IBE involves selecting the hypothesis that would best explain the available body of data or evidence, a process that is crucial to making sound decisions but is also vulnerable to bias and errors of judgment. Within this context, the purpose of our article is to explore how the IBE process and the selection of appropriate explanations impact decision making and problem solving in real life. To this end, we systematically analyze the role of IBE in the ARDESOS-DIAPROVE program, evaluating how this approach can enhance the teaching and practice of critical thinking