Simultaneous state estimation and control for nonlinear systems subject to bounded disturbances Deniz, Nestor Nahuel; Murillo, Marina Hebe; Sanchez, Guido Marcelo; Genzelis, Lucas Manuel; Giovanini, Leonardo Luis In this work, we address the problem to solve simultaneously state estimation and control of nonlinear systems under bounded disturbances using a moving horizon approach. Besides, necessary and sufficient conditions to guaranty the existence of a feasible solution are given, as well as stability results. The problem is posed as an optimization-based formulation which simultaneously estimates the optimal state trajectory and computes the future control actions to steer the system to a desired region of operation. Besides, computations of the length of the window required to neglect the effects of the initial conditions of the estimator part and the window length necessary to steer the state of the system to the desired operation region despite the disturbances are given.

Errancia y finalidad: variaciones del viaje odiseico en dos novelas latinoamericanas contemporáneas; Wandering and finality: variations of the odysseus voyage in two latin-american novels Guerra, Juan José Este trabajo analiza las transfiguraciones del viaje odiseico en las novelas Los pasos perdidos, de Alejo Carpentier, y Los detectives salvajes, de Roberto Bolaño. Luego de hacer un repaso de las apropiaciones más relevantes de la figura de Ulises en la tradición universal, se plantea que en esas dos novelas existe una disyuntiva entre el viaje como proceso simbólico que dota de sentido al itinerario y el viaje como mera errancia que constituye un fin en sí misma.; This work analyzes the transfigurations of the odysseous journey in the novels Los pasos perdidos, by Alejo Carpentier, and Los detectives salvajes, by Roberto Bolaño. After exploring the most relevant appropriations of the figure of Ulysses in the universal tradition, it is argued that in these two novels there is a disjunction between the journey as a symbolic process that gives meaning to the itinerary and the journey as mere wandering that constitutes an end in itself.

Violencia política y disciplinamiento social durante la última dictadura militar argentina. Modalidades represivas en Bahía Blanca, Argentina (1976-1977); Political Violence and Social Disciplining during the Last military Dictatorship in Argentina. Forms of Repression in Bahía Blanca, Argentina (1976-1977); Violência política e disciplinamento social durante a última ditadura militar argentina. Modalidades repressivas em Bahía Blanca, Argentina (1976-1977) Montero, María Lorena Desde una lógica situada, este artículo analiza las características que asumieron las modalidades represivas en una subdivisión del V Cuerpo de Ejército que durante la última dictadura militar argentina tenía asiento en la ciudad de Bahía Blanca. Para abordar las modalidades represivas dominantes en la Subzona 51 se distinguirán espacios punitivos, niveles de violencia registrados y formas de articulación entre dimensiones legales e ilegales y secretas y visibles de la represión a escala local. Dicho análisis permite reconstruir un mapa represivo complejo cuyos puntos nodales estaban configurados por los Centros Clandestinos de Detención y Exterminio, lugares transitorios de encierro y tortura, ámbitos de ?blanqueamiento? y dependencias castrenses en general. Esos espacios no sólo estaban unidos entre sí, sino que formaban parte de una trama que incluía a las fuerzas represivas que actuaban en las calles de la ciudad y en instituciones específicas como las dependientes del Servicio Penitenciario Bonaerense.; From a perspective that recognizes the local articulation of processes of national scope, this article analyses the characteristics of the forms of repression in a subdivision of the 5th Army Corps, headquartered in Bahía Blanca (Argentina) during the last military dictatorship in Argentina. To approach the dominant repressive practices in subarea 51, in this paper, we will distinguish punitive spaces, the levels of violence recorded, and the forms of articulation between legal and illegal, and secret and visible dimensions of local-scale-repression. The analysis serves to reconstruct a complex repressive map whose nodal points were configured by the Clandestine Detention and Extermination Centers operating as transitory locations for confinement and torture and sites for "blanqueamiento" and military bodies in general. These spaces were connected to each other, and they formed part of a plot that involved the repressive forces that had an impact in the city's streets and in specific institutions such as those that depended on the Buenos Aires Prison Service. The heterogeneous corpus of this study (made up by burocratic records of State agencies, memoirs of the victims and newspaper articles) will be addressed based on the integration of qualitative and quantitative methods.; Desde uma perspectiva que reconhece as articulações locais dos processos que tiveram alcance nacional, este artigo analisa as características que assumiram as modalidades repressivas em uma subdivisão do V Corpo de Exército que durante a última ditadura militar argentina estavam localizados na cidade de Bahía Branca (Argentina). Para abordar as práticas repressivas dominantes na Subzona 51 distinguiram-se espaços punitivos, níveis de violência registrados e formas de articulação entre dimensiones legais e ilegais e secretas e visíveis da repressão a escala local. Tal análise permite reconstruir um mapa repressivo complexo cujos pontos nodais estavam configurados pelos Centros Clandestinos de Detenção e Extermínio, lugares transitórios de confinamento e tortura, âmbitos de branqueamento e dependências castrenses em geral. Esses espaços não só estavam unidos entre si, mas formavam parte de uma trama que incluía as forças repressivas que agiam nas ruas da cidade e em instituições específicas como as dependentes do Serviço Penitenciário Bonaerense. O heterogéneo corpus desta pesquisa (integrado por registros burocráticos das agências estatais, memórias dos retaliados e artigos jornalísticos) será abordado a partir da integração de métodos quantitativos e qualitativos.

Pectin Hydrolysates from Different Cultivars of Pink/Red and White Grapefruits (Citrus Paradisi [macf.]) as Culture and Encapsulating Media for Lactobacillus Plantarum la Cava, Enzo Luciano Marcelo; Gerbino, Oscar Esteban; Sgroppo, Sonia Cecilia; Gomez Zavaglia, Andrea Citrus pectin hydrolysates (Citrus paradisi [Mafc.]) from “Foster,” “Red Shambar,” “Tangelo Orlando,” and “Citrumelo Swingle” cultivars were obtained by partial chemical hydrolysis and their properties as culture media (sole carbon/nutrient source) and encapsulating agents of Lactobacillus plantarum CIDCA 83114 were evaluated. The concentration of neutral sugars was maximal after 2‐hour hydrolysis. All hydrolysates were rich in glucose >xylose >galactose >galacturonic acid >mannose >arabinose. “Citrumelo Swingle” cultivar was the one with the highest concentration of xylose. After 24 hr of fermentation with L. plantarum CIDCA 83114, bacterial viability increased from 6.76 ± 0.14 to almost 9 log CFU/mL, and lactic acid concentration, from 2.63 ± 0.41 to 7.82 ± 0.15 mmol/L in all hydrolysates. Afterwards, bacteria were entrapped in pectate‐calcium beads by ionotropic gelation. Bacterial viability did not significantly decrease after freeze‐drying and storage the beads at 4 °C for 45 days.

Establishment and characterization of a novel tissue-specific dna construct and culture system with potential for avian bioreactor generation Pérez Sáez, Juan Manuel; Bussmann, Leonardo Edmundo; Bussmann, Ursula Agnes Transgenic chickens are of great interest for the production of recombinant proteins in their eggs. However, the use of constitutive strong promoters or the tissue-specific ovalbumin promoter for the generation of the transgenic chickens have different drawbacks that have to be overcome in order to make chicken bioreactor an efficient production system. This prompted us to investigate the use of an alternative tissue-specific promoter, the vitellogenin promoter, which could overcome the difficulties currently found in the generation of chicken bioreactors. In the present work we establish and characterize a DNA construct consisting of a fragment of the 5´-flanking region of the chicken vitellogenin II gene cloned in a reporter vector. This construct is capable of showing the ability of the promoter to drive expression of a reporting gene in a tissue-specific manner and in a way that closely resembles physiologic regulation of vitellogenin, making it an ideal candidate to be used in the future for generation of avian bioreactors. Besides, we validate an in vitro culture system to test the performance of the DNA construct under study that could be used as a practical tool before generating any transgenic chicken. These results are important since they provide the proof of concept for the use of the vitellogenin promoter for future genetic modification of chickens bioreactors with improved characteristics in terms of quality of the recombinant protein produced.

Microbial community composition and network analyses in arid soils of the Patagonian Monte under grazing disturbance reveal an important response of the community to soil particle size Marcos, Magalí Silvina; Bertiller, Monica Beatriz; Olivera, Nelda Lila The effects of livestock grazing on soil microbial communities are not fully understood in arid regions, where water limitations can have significant consequences on soil health and biological processes. Neither are understood the effects of livestock grazing on the interactions among members of the microbial communities. Here, we used high-throughput amplicon sequencing and co-occurrence network analyses to study changes in microbial community composition and networks in soil from plant-patches and inter-patches under sheep grazed and non-grazed conditions within an arid region of Patagonia. In addition, we analyzed soil and vegetation properties that could be influencing the observed microbial patterns. We detected over 2,000 amplicon sequence variants (ASVs) in soils from plant-patches and a similar number in inter-patches, which abundance shifted between the non-grazed and the grazed sites. Among them, members of the Actinomycetales, Solirubrobacterales, Pedosphaerales and Rhizobiales were present. We further found that connections among them in the network analysis were significantly affected by soil texture. Moreover, soil particle size explained between 24.7% and 31.9% of the variance in microbial community composition. Positive network connections increased from 57.8% in the non-grazed site to 88.6% in the grazed site. This may suggest either an increase in cooperative associations within the community, as a strategy to survive under the stressful conditions imposed by grazing, or a selection of microorganisms with similar niche requirements. We further concluded that members of the Actinomycetales and Rhizobiales seem to have a keystone role in the soil communities from this arid ecosystem.

Richness and distribution of Araneidae (Araneae) from Iberá Marshlands, Corrientes, Argentina Zanone, Ivo; Avalos, Gilberto El Iberá está entre los sistemas de humedales más importantes del Neotrópico. Abarca tres provincias fitogeográficas, según Carnevali: Chaco, Espinal y Paranaense. Araneidae está entre las familias de arañas más diversas del mundo. Aquí analizamos la abundancia y riqueza de Araneidae de los Esteros del Iberá usando diez localidades diferentes, considerando las diferencias de ambientes como sabana, bosque, pirizal, y plantaciones de Eucaliptus y Pinus, cubriendo las tres provincias fitogeográficas. Se recolectaron 1296 individuos distribuidos en 22 géneros y 82 especies. La más abundante fue Metazygia gregalis, con 143 individuos; Eustala mostró la mayor riqueza, con 13 especies. La provincia Paranaense mostró la riqueza mayor. Se aportan 12 nuevos registros para Argentina y 15 para la Corrientes. Siendo un área tan rica, sugerimos que la gestión tienda a la conservación de los Esteros del Iberá y realzando la promoción de la heterogeneidad espacial natural.; Iberá is among the most important wetland systems in the Neotropics. It covers three phytogeographic provinces, accordingto Carnevali: Chaco, Espinal and Paranaense. Araneidae is one of the most diverse spider families in the world. Here we analysethe abundance and richness of Araneidae of the Iberá wetland using ten different locations, considering different environmentssuch as savanna, woodlands, pirizal and Eucaliptus and Pinus plantations, covering the three phytogeographic provinces. We found1296 individuals, belonging to 22 genera and 82 species. The most abundant spider was Metazygia gregalis, with 143 individuals,and Eustala showed the highest richness, with 13 species. Paranaense province had the highest species richness. 12 new recordsare given for Argentina and 15 for Corrientes. Being such a rich area, we suggest conservation management in the reserve shouldaim at promoting natural spatial heterogeneity.

Binding silver to chitooligosaccharides through N-heterocyclic carbenes: Synthesis and antimicrobial activity Necol, Marcelo R.; Vela Gurovic, Maria Soledad; Ruiz Díaz, Soledad; Silbestri, Gustavo Fabián Silver containing products are widely used as antibacterial agents in wound dressings. The mechanism of action relies on the high reactivity of silver ions, which is also responsible of the lack of selectivity and stability of these products. Stabilization of silver by complexation and binding to a biocompatible material that selectively interacts with microorganisms will certainly lead to improved products. To prove this, chitooligosaccharides and one of its building blocks, D-glucosamine, were complexed with silver through the stable N-heterocyclic carbene (NHC) bond. Two amino moieties from each carbohydrate reacted to form a diimine, which was further converted into an imidazolium salt. This later precursor was complexed to silver to yield the NHCs complexes. The successively generated compounds were spectroscopically characterized by FT-IR, NMR, Inductively Coupled Plasma atomic emission spectroscopy and tested for activity against E. coli, Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Candida albicans. The antimicrobial profiles of the silver complexes were similar or better than that of silver nitrate and generally more effective than the antiseptic of reference, PVP iodine. Complexation of silver to biocompatible and microbial selective materials through NHC bonds is a promising approach to develop more efficient silver carriers and wound care products.

Formation of localized magnetic states in silicene in an external electric field Villarreal, J.; Escudero, Federico Nahuel; Ardenghi, Juan Sebastian; Jasen, Paula Verónica In the present work we study theoretically the localized behavior of transition metal adatoms and silicene interaction in an external electrical field. Considering the electron-electron interaction by adding a Hubbard term in the mean-field approximation, we obtain the spin-polarized density of states on the impurity and total density of states in terms of the hybridization strength with the sublattices and the external electric field, showing the possible values for the Hubbard parameter U and the Fermi energy μ at which magnetization arises. In particular, on-site impurities energies below and above the Dirac point are studied, where the magnetization shows a strong dependence on the hybridization parameters of the A and B sublattice with the impurity and a spin-flip transition for critical external electric fields. Finally, a comparison is done between silicene, germanene and stanene, showing no substantial difference when the on-site energy of the impurity is below the Dirac point.

The distribution of symmetry of a naturally reductive nilpotent Lie group Reggiani, Silvio Nicolás We show that the distribution of symmetry of a naturally reductive nilpotent Lie group coincides with the invariant distribution induced by the set of fixed vectors of the isotropy. This extends a known result on compact naturally reductive spaces. We also address the study of the quotient by the foliation of symmetry.

Analogues of Human Granulysin as Antimycobacterial Agents Siano, Alvaro Sebastían; Tonarelli, Georgina Guadalupe; Larpin, Daniel; Imaz, María Susana; Alvarez, Claudia; Zerbini, Elsa Virginia Antimicrobial peptides are essential components of innate defense mechanisms and make promising candidates for novel anti-infective agents. The advantages of these peptides in clinical applications include their potential for broad-spectrum and rapid bactericidal activities, and low propensity for resistance development, whereas possible disadvantages include their high cost, limited stability, and unknown toxicology and pharmacokinetics. Granulysin (Gr) is a cytolytic and proinflammatory molecule expressed by activated human cytotoxic T lymphocytes and natural killer (NK) cells. This paper aims to study bacteriostatic and bactericidal activity against Mycobacterium tuberculosis by synthetic analogues of human Gr between 12 and 26 amino acids (AA) and their acyl derivatives. Considering results of previous studies, five new peptides were designed: a cyclic of 20 AA (Gr-SL1); one of 21 AA (linear) (Gr-SL2), another of 12 AA (cyclic) (Gr-SL3) and two lipopeptides (Gr-SL3-lauric and Gr-SL3-palmitic). Peptides were manually synthesized as C-terminal carboxamides by the solid-phase method following Fmoc chemistry. Gr synthetic analogues were purified by reverse phase HPLC and analyzed by analytical C18RP-HPLC and Maldi Tof. The antimycobacterial activity of synthesized Gr analogues was assessed using a microdilution susceptibility test as described previously. Although peptides studied here had neither higher antimycobacterial activity nor lower toxicity than analogs of human Gr previously evaluated, fresh knowledge concerning the influence of acylation and structural aspects analyzed will optimize the design of novel peptides combining the most favorable aspects for the maintenance of antimycobacterial activity with minimum toxicity.

Hidden paintings, forgotten histories: a micro-stratigraphic approach to study coated rock art Gheco, Lucas Ignacio; Tascon, Marcos; Gastaldi, Marcos Roman; Ahets Etcheberry, Eugenia Inés; Pereda, Soledad; Mastrangelo, Noemi Elisa; Quesada, Marcos Nicolás; Marte, Fernando Daniel Is it possible to detect rock paintings coated by natural or anthropic concretions? In this work, a methodology to discover and characterize underlying paintings is proposed. This approach combines chemical studies by micro-Raman and SEM-EDS of micro-stratigraphic samples taken from the paintings and support rock. As a case of study, it is described the research performed in the archeological site of Oyola in the northwest of Argentina. Strong evidences of red, black, and white hidden paintings have been found. In addition, the method herein presented is thoroughly evaluated pointing out their possibilities and limitations as a tool for the understanding of the historical processes involving production and transformation of the rock art panels. To this end, the methodology was proofed to be a successful exploratory approach for painting detection, expanding its capabilities when complemented with non-invasive characterization techniques.

Los medios de comunicación en la escuela. Cuando la muerte se torna noticia; The media at school. When death turns into news Saez, Virginia; Cerullo, Natalia Carolina El artículo presenta los hallazgos de una investigación socioeducativa sobre los discursos mediáticos de cuatro diarios argentinos, en el período 1993-2011. El objetivo consistió en analizar las características de las prácticas discursivas de las conductas de riesgo y suicidio juvenil en el espacio escolar. Los resultados amplían la base empírica con la que pensar las representaciones de la escuela.; This article introduces the findings of a socioeducative investigation on media discourses of four argentine newspapers, in the 1993-2011 period. The objective was to analyze the characteristics of the discoursive practices of the risk- taking behaviors and juvenile suicide in the school space. The results increase our empirical knowledge to think the representations on school.

Scavenging activity of Dermestes maculatus (Coleoptera: Dermestidae) on burned cadaveric tissue Zanetti, Noelia Inés; Ferrero, A. A.; Centeno, N. D. The aim of this work was to study the effect that fire exposure in tissues may have on Dermestes maculatus DeGeer (Dermestidae: Dermestini) taphonomic behaviour under controlled conditions. Two different times of fire exposure (treatments) were evaluated, 15 min and 30 min, after spraying pig trotters with gasoil. The pig trotters were provided to adult hide beetles and both were maintained at 24 ± 0.1°C, 55.4% ± 2% relative humidity, and a 12:12 h day/night cycle. An unburned pig trotter was used as a control for each treatment. Observations were made and photographs were taken every 4–5 days for 4 months. Qualitative and quantitative analyses were performed. Dermestes maculatus was able to feed and reproduce on burned tissues. Beetles in adult and larvae stages produced different types of marks in several kinds of tissues such as integumental, connective, and muscular, in the controls and treatments. Apparently, 15 min of burning the pig trotters were not sufficient enough to cause differences in the taphonomic marks with respect to the control, but post mortem burning for 30 min may have implicated changes (lesser insect damage represented by lesser number and surface of both depressions and holes were found with respect to the control; greater surfaces and diameters were noticed compared to those found in the unburned pig trotters). The shape of the marks was equal in the controls and treatments.

"Porque nos daba bronca". Las emociones en la acción política de niños/as en una casa tomada; “Because we felt annoyed”. Emotions in the production of the political action of children that live in an occupied house Shabel, Paula Nurit El pensamiento moderno se ha configurado en dicotomías como adultez/infancia y pensar/sentir, que se sintetizan en una división permanente entre lo racional y lo irracional desde donde se ha analizado la acción humana. Sin embargo, la antropología ha desarrollado diversas líneas de trabajo que problematizan estos esquemas aportando otras miradas sobre la niñez y sobre la movilización política. En este mismo sentido, y a partir de un extenso estudio etnográfico, nos proponemos analizar los modos en los que los/as niños/as de entre 8 y 15 años que viven en una casa tomada de la Ciudad de Buenos Aires producen acciones políticas colectivas enraizadas en sus emociones compartidas.; Modern thought has been configured in dichotomies such as adulthood/infancy and thinking/feeling, which are synthesized in a permanent division between the rational and the irrational from where human action has been analyzed. However, anthropology has developed several lines of work that problematize these schemes providing alternative views on childhood and on political mobilization. In this same sense, and from an extensive ethnographic study, we propose to analyze the ways in which children between the ages of 8 and 15 living in an occupied house from the City of Buenos Aires produce collective political actions rooted in their shared emotions.

The evolution of ultra-massive white dwarfs Camisassa, María Eugenia; Althaus, Leandro Gabriel; Corsico, Alejandro Hugo; de Gerónimo, Francisco César; Miller Bertolami, Marcelo Miguel; Novarino, Maria Leonela; Rohrmann, Rene Daniel; Wachlin, Felipe Carlos; García Berro, Enrique Ultra-massive white dwarfs are powerful tools used to study various physical processes in the asymptotic giant branch (AGB), type Ia supernova explosions, and the theory of crystallization through white dwarf asteroseismology. Despite the interest in these white dwarfs, there are few evolutionary studies in the literature devoted to them. Here we present new ultra-massive white dwarf evolutionary sequences that constitute an improvement over previous ones. In these new sequences we take into account for the first time the process of phase separation expected during the crystallization stage of these white dwarfs by relying on the most up-to-date phase diagram of dense oxygen/neon mixtures. Realistic chemical profiles resulting from the full computation of progenitor evolution during the semidegenerate carbon burning along the super-AGB phase are also considered in our sequences. Outer boundary conditions for our evolving models are provided by detailed non-gray white dwarf model atmospheres for hydrogen and helium composition. We assessed the impact of all these improvements on the evolutionary properties of ultra-massive white dwarfs, providing updated evolutionary sequences for these stars. We conclude that crystallization is expected to affect the majority of the massive white dwarfs observed with effective temperatures below 40 000 K. Moreover, the calculation of the phase separation process induced by crystallization is necessary to accurately determine the cooling age and the mass-radius relation of massive white dwarfs. We also provide colors in the Gaia photometric bands for our H-rich white dwarf evolutionary sequences on the basis of new model atmospheres. Finally, these new white dwarf sequences provide a new theoretical frame to perform asteroseismological studies on the recently detected ultra-massive pulsating white dwarfs.

Assessment of the sustainable potential of parking lots in Bahía Blanca City, Argentina Gentili, Jorge Osvaldo; Fernández, María Eugenia; Ortuño Cano, María de Los Ángeles; Campo, Alicia María The aim of this study is to characterize the site, location, and morphology of parking lots in downtown Bahía Blanca; to determinetheir contribution to environmental urban problems; and to suggest strategies to turn them into spaces in which to apply newurban principles. Strategies related to sustainable urban development, with comprehensive solutions for energy efficiency,sustainable construction, biomass conservation, and resource optimization were considered. The results show that parking lotshave increased as urban land use typology within the city downtown. It was observed that parking lots are concentrated in someareas of the city downtown, and that concrete and sheet metal are the main construction materials. The lack of vegetation is also amajor characteristic. Their location in urban areas implies vehicle circulation on downtown streets and avenues, which is directlyassociated to atmospheric pollution. Finally, each parking lot potential was analyzed in order to implement sustainabledevelopment measures, related to green policies, design, and construction.

El mapa social de la Aglomeración Gran Buenos Aires como evidencia empírica de modelos urbanos Buzai, Gustavo Daniel; Marcos, Mariana El trabajo tiene como objetivo realizar un análisis del mapa social de la Aglomeración Gran Buenos Aires a partir de la aplicación técnica de procedimientos de análisis multivariado -la asociación espacial por superposición temática- y teniendo como marco conceptual aspectos modelísticos de la estructura socioespacial de las grandes ciudades de América Latina. Para lograr este objetivo, además del análisis de modelos urbanos, se seleccionan variables de entre los datos más recientes disponibles -Censo 2001-, que claramente presentan una dicotomía entre situaciones favorables y desfavorables, y se aplica una metodología de estandarización que lleva a la obtención de puntajes de clasificación espacial como síntesis de las relaciones. De esta manera, se obtienen resultados parciales que presentan situaciones contrastantes, las cuales se combinan en un resultado final en el que, a su vez, se incorporan entidades geográficas puntuales como las urbanizaciones cerradas y los asentamientos precarios, ambos representantes de niveles socioeconómicos claramente opuestos.

Video summarisation by deep visual and categorical diversity Atencio, Pedro; Sanchez Torres, German; Branch, John; Delrieux, Claudio Augusto The authors propose a video-summarisation method based on visual and categorical diversities using pre-trained deep visual and categorical models. Their method extracts visual and categorical features from a pre-trained deep convolutional network (DCN) and a pre-trained word-embedding matrix. Using visual and categorical information they obtain a video diversity estimation, which is used as an importance score to select segments from the input video that best describes it. Their method also allows performing queries during the search process, in this way personalising the resulting video summaries according to the particular intended purposes. The performance of the method is evaluated using different pre-trained DCN models in order to select the architecture with the best throughput. They then compare it with other state-of-the-art proposals in video summarisation using a data-driven approach with the public dataset SumMe, which contains annotated videos with per-fragment importance. The results show that their method outperforms other proposals in most of the examples. As an additional advantage, their method requires a simple and direct implementation that does not require a training stage.

Evidence of developmental escape from transcriptional gene silencing in MESSI retrotransposons Sanchez, Diego Hernan; Gaubert, Hervé; Yang, Weibing Transposable elements (TEs) are ubiquitous genomic features. ‘Copy-and-paste’ long-terminal-repeat (LTR) retrotransposons have been particularly successful during evolution of the plant kingdom, representing a substantial proportion of genomes. For survival in copious numbers, these TEs may have evolved replicative mobilization strategies that circumvented hosts’ epigenetic silencing. Stressful circumstances are known to trigger the majority of known mobilizing plant retrotransposons, leading to the idea that most are activated by environmental signals. However, previous research revealed that plant developmental programs include steps of silencing relaxation, suggesting that developmental signals may also be of importance for thriving parasitic elements. Here, we uncover an unusual family of giant LTR retrotransposons from the Solanum clade, named MESSI, with transcriptional competence in shoot apical meristems of tomato. Despite being recognized and targeted by the host epigenetic surveillance, this family is activated in specific meristematic areas fundamental for plant shoot development, which are involved in meristem formation and maintenance. Our work provides initial evidence that some retrotransposons may evolve developmentally associated escape strategies to overcome transcriptional gene silencing in vegetative tissues contributing to the host's next generation. This implies that not only environmental but also developmental signals could be exploited by selfish elements for survival within the plant kingdom