Avances en la investigación de la relación patogeno-hospedante y de la resistencia genética a enfermedades de la caña de azúcar en Argentina

Esta contribución presenta avances en la investigación de la variabilidad y resistencia genética con relación a “Roya marrón” y “Estría roja” de la caña de azúcar en Argentina. Resultados experimentales de la inoculación con roya en condiciones controladas permitieron postular que tanto la actividad peroxidasa basal como la tasa de su crecimiento con posterioridad a la infección serían mecanismos complementarios que favorecen la expresión de la resistencia a la enfermedad. También se investigó la diversidad molecular en poblaciones de roya con base en 538 marcadores AFLP a partir de muestreos en diferentes variedades y en una amplia faja de distribución de la enfermedad en el NOA. No se detectaron estructuras genéticas diferenciadas según orígenes, comportándose las diferentes poblaciones como una única gran población indiferenciada de uredosporos con alto grado de variabilidad genética intrínseca. Con relación a Estría roja se logró optimizar una técnica efectiva para el aislamiento, identificación y caracterización genética del agente responsable de la enfermedad. Los resultados obtenidos permitieron confirmar que Acidovorax avenae es el agente responsable de estría roja de la caña de azúcar en Argentina, siendo ésta la primera caracterización realizada en la región cañera para esta patología. Por otra parte el análisis de perfiles de REP-PCR y RAPD confirmó la presencia de al menos cuatro biotipos de la enfermedad en aislados de Salta y Tucumán. La existencia de diversidad genética entre aislamientos permite diseñar estrategias de control mediante el uso de variedades resistentes.The paper presents recent progress in the investigation of variability and genetic resistance in relation to Rust and Red stripe diseases of sugar cane in Argentina. Experimental results for rust innoculation under controlled conditions served to postulate that both basal peroxidase activity and its rate of increase after innoculation with the disease could be complementary mechanisms in the expression of resistance in different cultivars. Molecular diversity of rust populations collected in the field in North West Argentina were also investigated based on 538 AFLP markers. Samples collected in different varieties and sites indicated that rust uredospores populations correspond with a single mixed undifferentiated population with a high degree of intrinsic genetic variability. In regard to Red stripe it was possible to optimize an effective procedure for the isolation, identification and genetic characterization of the disease agent. Results permitted for the first time the identification of Acidovorax avenae as the agent responsible for the disease in Argentina. The profile analysis for REP-PC and RAPD indicated the presence of at least four different biotypes of the disease in Salta and Tucumán. The occurrence of genetic diversity among isolates permits the design of strategies for the control of the disease by means of resistant varieties.Fil: Mariotti, Jorge Alberto. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Machado Assefh, Cristina Renata. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; ArgentinaFil: Rech, G.. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Fontana, P. D.. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Collavino, N. G.. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Pocoví, M. I.. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Rago, A. M.. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Daz, Mirta Elizabeth. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; Argentin

The PEP survey: clustering of infrared-selected galaxies and structure formation at z~2 in the GOODS South

ABRIDGED-This paper presents the first direct estimate of the 3D clustering properties of far-infrared sources up to z~3. This has been possible thanks to the Pacs Evolutionary Probe (PEP) survey of the GOODS South field performed with the PACS instrument onboard the Herschel Satellite. An analysis of the two-point correlation function over the whole redshift range spanned by the data reports for the correlation length, r_0~6.3 Mpc and r_0~6.7 Mpc, respectively at 100um and 160um, corresponding to dark matter halo masses M>~10^{12.4} M_sun. Objects at z~2 instead seem to be more strongly clustered, with r_0~19 Mpc and r_0~17 Mpc in the two considered PACS channels. This dramatic increase of the correlation length between z~1 and z~2 is connected with the presence of a wide, M>~10^{14} M_sun, filamentary structure which includes more than 50% of the sources detected at z~2. An investigation of the properties of such sources indicates the possibility for boosted star-forming activity in those which reside within the overdense environment with respect of more isolated galaxies found in the same redshift range. Lastly, we also present our results on the evolution of the relationship between luminous and dark matter in star-forming galaxies between z~1 and z~2. We find that the increase of (average) stellar mass in galaxies between z~1 and z~2 is about a factor 10 lower than that of the dark matter haloes hosting such objects ([z~1]/[z~2] ~ 0.4 vs M_{halo}[z~1]/M_{halo}[z~2] ~ 0.04). Our findings agree with the evolutionary picture of downsizing whereby massive galaxies at z~2 were more actively forming stars than their z~1 counterparts, while at the same time contained a lower fraction of their mass in the form of luminous matter.Comment: 14 pages, 8 figures, MNRAS accepte

DYNAMIC BEHAVIOR ANALYSIS OF THE GLOMERULO-TUBULAR BALANCE MEDIATED BY THE EFFERENT BLOOD VISCOSITY

International audienceA mathematical model of the dynamics of a single nephron function relating glomerulo-tubular balance, tubule-glomerular feedback, and peritubular blood viscosity is developed. Based upon experimental data, the model shows that complex behaviors of the nephron can be modulated by changes in the efferent arteriole blood viscosity. The main hypothesis is that the reabsorbed mass flow is modulated by the hematocrit of the efferent arteriole, in addition to the Starling forces. From a mathematical perspective, these behaviors can be explained by a bifurcation diagram analysis where the efferent blood viscosity is taken as the bifurcation parameter. This analytical description allows to predict changes in proximal convoluted tubule reabsorption, following changes in peritubular capillary viscosity generated by periodic changes in the glomerular filtration rate. Thus, the model links the tubule-glomerular feedback with the glomerular tubular balance

A dusty star-forming galaxy at <i>z</i> = 6 revealed by strong gravitational lensing

Since their discovery, submillimetre-selected galaxies have revolutionized the field of galaxy formation and evolution. From the hundreds of square degrees mapped at submillimetre wavelengths, only a handful of sources have been confirmed to lie at z > 5 and only two at z ≥ 6. All of these submillimetre galaxies are rare examples of extreme starburst galaxies with star formation rates of ≳1,000 M⊙ yr−1 and therefore are not representative of the general population of dusty star-forming galaxies. Consequently, our understanding of the nature of these sources, at the earliest epochs, is still incomplete. Here, we report the spectroscopic identification of a gravitationally amplified (μ = 9.3 ± 1.0) dusty star-forming galaxy at z = 6.027. After correcting for gravitational lensing, we derive an intrinsic less-extreme star formation rate of 380 ± 50 M⊙ yr−1 for this source and find that its gas and dust properties are similar to those measured for local ultra luminous infrared galaxies, extending the local trends to a poorly explored territory in the early Universe. The star-formation efficiency of this galaxy is similar to those measured in its local analogues, despite a ~12 Gyr difference in cosmic time

Genomic Expression Libraries for the Identification of Cross-Reactive Orthopoxvirus Antigens

Increasing numbers of human cowpox virus infections that are being observed and that particularly affect young non-vaccinated persons have renewed interest in this zoonotic disease. Usually causing a self-limiting local infection, human cowpox can in fact be fatal for immunocompromised individuals. Conventional smallpox vaccination presumably protects an individual from infections with other Orthopoxviruses, including cowpox virus. However, available live vaccines are causing severe adverse reactions especially in individuals with impaired immunity. Because of a decrease in protective immunity against Orthopoxviruses and a coincident increase in the proportion of immunodeficient individuals in today's population, safer vaccines need to be developed. Recombinant subunit vaccines containing cross-reactive antigens are promising candidates, which avoid the application of infectious virus. However, subunit vaccines should contain carefully selected antigens to confer a solid cross-protection against different Orthopoxvirus species. Little is known about the cross-reactivity of antibodies elicited to cowpox virus proteins. Here, we first identified 21 immunogenic proteins of cowpox and vaccinia virus by serological screenings of genomic Orthopoxvirus expression libraries. Screenings were performed using sera from vaccinated humans and animals as well as clinical sera from patients and animals with a naturally acquired cowpox virus infection. We further analyzed the cross-reactivity of the identified immunogenic proteins. Out of 21 identified proteins 16 were found to be cross-reactive between cowpox and vaccinia virus. The presented findings provide important indications for the design of new-generation recombinant subunit vaccines

Shells and humans: molluscs and other coastal resources from the earliest human occupations at the Mesolithic shell midden of El Mazo (Asturias, Northern Spain)

Human populations exploited coastal areas with intensity during the Mesolithic in Atlantic Europe, resulting in the accumulation of large shell middens. Northern Spain is one of the most prolific regions, and especially the so-called Asturian area. Large accumulations of shellfish led some scholars to propose the existence of intensification in the exploitation of coastal resources in the region during the Mesolithic. In this paper, shell remains (molluscs, crustaceans and echinoderms) from stratigraphic units 114 and 115 (dated to the early Mesolithic c. 9 kys cal BP) at El Mazo cave (Asturias, northern Spain) were studied in order to establish resource exploitation patterns and environmental conditions. Species representation showed that limpets, top shells and sea urchins were preferentially exploited. One-millimetre mesh screens were crucial in establishing an accurate minimum number of individuals for sea urchins and to determine their importance in exploitation patterns. Environmental conditions deduced from shell assemblages indicated that temperate conditions prevailed at the time of the occupation and the morphology of the coastline was similar to today (rocky exposed shores). Information recovered relating to species representation, collection areas and shell biometry reflected some evidence of intensification (reduced shell size, collection in lower areas of exposed shores, no size selection in some units and species) in the exploitation of coastal resources through time. However, the results suggested the existence of changes in collection strategies and resource management, and periods of intense shell collection may have alternated with times of shell stock recovery throughout the Mesolithic.This research was performed as part of the project “The human response to the global climatic change in a littoral zone: the case of the transition to the Holocene in the Cantabrian coast (10,000–5000 cal BC) (HAR2010-22115-C02-01)” funded by the Spanish Ministry of Economy and Competitiveness. AGE was funded by the University of Cantabria through a predoctoral grant and IGZ was funded by the Spanish Ministry of Economy and Competitiveness through a Juan de la Cierva grant. We also would like to thank the University of Cantabria and the IIIPC for providing support, David Cuenca-Solana, Alejandro García Moreno and Lucia Agudo Pérez for their help. We also thank Jennifer Jones for correcting the English. Comments from two anonymous reviewers helped to improve the paper