We study fully developed, steady granular flows confined between parallel flat frictional sidewalls using numerical simulations and experiments. Above a critical rate, sidewall friction stabilizes the underlying heap at an inclination larger than the angle of repose. The shear rate is constant and independent of inclination over much of the flowing layer. In the direction normal to the free surface, the solid volume fraction increases on a scale equal to half the flowing layer depth. Beneath a critical depth at which internal friction is invariant, grains exhibit creeping and intermittent cage motion similar to that in glasses, causing gradual weakening of friction at the walls.

Sporeling coalescence in Gracilaria chilensis Bird, McLachlan et Oliveira produces genetically polymorphic, chimeric individuals. If this is common in red algae, it may have significant biological consequences. In this study, we evaluate the hypotheses that coalescence is widespread among the Rhodophyta and that specific and convergent morphological and ecological responses characterize this as a unique growth style among marine algae. A literature survey on coalescence was undertaken to assess the distribution of this condition in the Florideophycidae. Sixty-two (54.9%) of 113 species considered germinated to form a disk. Subsequent development in 37 of these species showed crust formation and coalescence during development with other crusts in 31 species (84%). Coalescing red algae were members of the orders Ahnfeltiales, Corallinales, Gigartinales, Gracilariales, Halymeniales, Palmariales, and Rhodymeniales. Ultrastructural studies in species of Ahnfeltiopsis, Chondrus, Gracilaria, Mazzaella, and Sarcothalia suggested a common pattern of early development. Newly released, naked spores may fuse into a single cell, as they do in Chondrus canaliculatus, or they may develop individual cell walls that later are surrounded by a thickened common wall. Ultrastructural studies demonstrated two kinds of immediate development after the first mitotic division: direct development by symmetric divisions resulting in discoid sporelings or an indirect asymmetric arrangement of divisions before a diskoid sporeling was formed. Germination in coalescing species is a linear function of the initial spore density, whereas in noncoalescing species maximum germination occurs at intermediate densities. In the field, coalescing species may recruit either from solitary or aggregated spores. However, survival is significantly higher for plantlets grown from a larger number of coalescing spores. Total number of erect axes formed by the coalesced mass is a logarithmic function of the initial number of spores. Thus, germlings grown from a larger number of coalescing spores exhibited a larger photosynthetic canopy than do plantlets grown from a few spores. Juveniles and mature clumps grown from a coalescing mass may exhibit size inequalities among erect axes, with the larger axes located toward the center of the clump. These larger axes mature first or, in some cases, are the only to produce spores. The widespread occurrence of coalescence in 1 roughly half the number of orders of the Florideophycidae, the similarity of the coalescence process, and the finding of various adaptive traits associated with coalescence characterizes this as a unique growth style, splitting the diversity of species now included in the Florideophycidae into two major groups: coalescing and noncoalescing Rhodophyta.

RESUMENLos potyvirus son uno de los grupos de virus más limitantes en los cultivos de papa (Solanum tuberosum y S. phureja) en el mundo, siendo PVY, PVV y PVA las especies más prevalentes. En este trabajo se evaluó la presencia de estos potyvirus en cuatro lotes de S. tuberosum cv. Diacol-Capiro y cuatro lotes de S. phureja cv. Criolla-Colombia ubicados en el oriente de Antioquia, analizando la cápside viral mediante RT-PCR/secuenciación Sanger y secuenciación de nueva generación (NGS) para S. tuberosum. Los resultados indicaron la ocurrencia de los potyvirus PVY y PVV en las muestras de S. tuberosum y S. phureja, respectivamente; siendo detectadas mediante cebadores específicos la presencia de tres diferentes cepas de PVY (PVY N , PVY NTN y PVY O ) en la región de estudio. Este hallazgo fue confirmado por NGS, obteniendo las secuencias completas de los genomas de estas tres cepas, lo que representa el primer reporte de PVY O en Colombia. Por su parte, los análisis de secuencias de la región CP de PVV indicaron niveles de identidad superiores a 99% con respecto a aislamientos del linaje PVV Phu reportado previamente en Antioquia. Estos hallazgos evidencian la necesidad de ajustar los sistemas de detección de virus en los programas de certificación de tubérculo-semilla de papa adelantados en el país.Palabras clave: Potyviridae, secuenciación de nucleótidos de alto rendimiento, Solanum phureja, Solanum tuberosum, virus de plantas. ABSTRACTPotyviruses are one of the most limiting viruses for the potato (Solanum tuberosum and S. phureja) production worldwide, being PVY, PVV and PVA the most prevalent species. In this work, we tested the presence of these viruses in four commercial S. tuberosum cv. Diacol-Capiro and S. phureja cv. Criolla-Colombia plots in eastern Antioquia using RT-PCR and Sanger sequencing of the coat protein (CP) region, as well as next generation sequencing (NGS) for S. tuberosum samples. Our results revealed the presence of a PVV strain infecting S. phureja with high sequence identity (>99%) to lineage PVV Phu previously reported in Antioquia. Three strains of PVY (PVY N , PVY NTN and PVY O ) were found to infect S. tuberosum. The presence of these three PVY strains was confirmed by NGS, allowing the assembly of their complete genomes. This is the first report of the full genome sequence of PVY o strain in Colombia. These findings highlight the need to adjust the tuber-seed certification programs currently implemented in the country.

<p class="Texto">El modelado y simulación de pequeños sistemas industriales ha adquirido gran importancia en los procesos de toma de decisiones, toda vez que les permite a microempresas fundamentar sus decisiones de producción. Este artículo hace un análisis de una empresa dedicada a la confección de ropa exterior masculina con una producción semanal promedio de 490 prendas. La motivación del estudio radica en el interés de incrementar su productividad; por esto, se desarrolló un modelo del sistema real con la herramienta Arena®, logrando identificar las partes de los procesos responsables de atrasos y “cuellos de botella” que permitieron plantear el escenario de solución. Este documento muestra los resultados de la simulación del sistema real y una comparación con un escenario de mejora que presentó un aumento en la productividad.<strong></strong></p>

Very little is known about the potential effects of endophytic infections on the host in algae, especially in terms of fitness. In this study, we report a first attempt at quantifying the effects of the endophytes Endophyton ramosum (Chlorophyta) and Pleurocapsa sp. (Cyanophyta) on the reproductive potential of their host Mazzaella laminarioides (Rhodophyta). Density of reproductive structures and spore germination rates was compared between infected and non-infected fronds. It was found that differences in density of reproductive structures between infected and non-infected fronds were not significant, which suggests that the level of maturity of the host is unaltered by the endophytes. On the other hand, carpospore germination rates significantly decreased when produced by fronds infected by the cyanobacterium Pleurocapsa sp. Thus, in the general context of host fitness, we discuss the fact that only some of the components of the reproductive output of M. laminarioides are negatively affected by the endophytes. KEY WORDS: Cyanobacteria · Endophyton ramosum · Endophyte infections · Fitness · Mazzaella laminarioides · Pleurocapsa Resale or republication not permitted without written consent of the publisherDis Aquat Org 42: [143][144][145][146][147][148] 2000 laminarioides (Bory) Fredericq (Gigartinales, Rhodophyta). This host is an ecologically and economically important species, abundant on the rocky intertidal zone along the coast of central and southern Chile. It is characterized by an alternation of isomorphic generations of lanceolate fronds issued from a perennial holdfast (Fig. 1a). The 2 infecting organisms are the cyanobacterium Pleurocapsa sp. and the filamentous green alga Endophyton ramosum Gardner (Fig. 1b,c). E. ramosum infects mainly the base of the fronds, where it causes tissue degradation and facilitates frond fracture (Fig. 1b,c;Correa et al. 1994), whereas Pleurocapsa sp. infects the entire frond, producing small but often numerous galls (Fig. 1d,e;Correa et al. 1993). Buschmann et al. (1997) suggested that tissue weakening by E. ramosum was the cause of a reduction in frond survival. In central Chile, 45 to 55% of the fronds have been recorded as infected by E. ramosum, compared to only 5 to 10% by Pleurocapsa sp. (Correa et al. 1997). It must be considered, however, that the latter pathogen displays a highly aggregated spatial distribution, with small areas of the beach having nearly all fronds heavily infected whereas the rest of the population remains uninfected . Furthermore, also suggested a potentially negative effect of the infections on host reproduction based on the observation that, in natural populations of M. laminarioides, full size and heavily diseased fronds were rarely mature.Based on the above, the objective of this study was to determine the extent to which endophytic infections affect the reproductive potential of Mazzaella laminarioides by comparing the differences in density of reproductive structures and spore germination rate between infected and non-inf...

RESUMENLas enfermedades virales son uno de los problemas más limitantes para la producción de papa en el mundo. Uno de los materiales de papa más susceptibles a los virus corresponde a Solanum phureja; sin embargo, en Colombia son pocos los estudios adelantados sobre los agentes causales que lo afectan. En este trabajo se realizó una caracterización molecular del Potato virus V (PVV) infectando plantas de S. phureja en Antioquia, utilizando métodos de secuenciación de nueva generación (NGS), pruebas de DAS-ELISA, RT-PCR en tiempo real (RT-qPCR) y RT-PCR convencional. Los resultados indican la ocurrencia de niveles muy variables de incidencia del virus entre lotes de cultivo (6,7 % a 86 %). El PVV tiene un genoma de 9828 nt que codifica para una poliproteína de 3066 aa y presenta dos variantes principales (Var_A y Var_B) en proporciones de 72 y 28 %. Estas variantes comparten altos niveles de identidad genética (99,7 % en todo el genoma) entre ellas y con respecto a la cepa PVV-Phureja reportada en Colombia, pero no con otras cepas del mundo (82-83 %). Con base en dichos genomas, se diseñaron y evaluaron en muestras foliares de S. phureja, dos pares de cebadores para la detección del virus en pruebas de RT-PCR (459 pb) y RT-qPCR (89 pb, Ct=12,08-21,86 y Tm= 78,7°C-80,2 °C), confirmándose la presencia de este virus en tejidos sintomáticos y asintomáticos de papa criolla. La ocurrencia generalizada de PVV en los cultivos de S. phureja indica la necesidad de incorporar en los programas de certificación de tubérculos-semilla de S. phureja en Colombia el diagnóstico de este virus.Palabras clave: DAS-ELISA, NGS, papa, Potyvirus, RT-qPCR. ABSTRACTViral diseases are one of the most limiting problems in the production of potato worldwide. Solanum phureja constitutes one of the most susceptible materials to viral diseases in Colombia; however, there are few studies on viruses infecting this crop. In the current study, we performed a molecular characterization of Potato virus V (PVV) that infects S. phureja, using different potato plots located in the province of Antioquia, using Next-Generation Sequencing (NGS), DAS-ELISA, real time RT-PCR (RT-qPCR) and RT-PCR. Results revealed variable levels of incidence among plots (6.7 %-86 %) and the presence of two slightly different variants (Var_A and Var_B) present in approximately 72 %:28 % ratio. These PVV strains have a genome of 9828 nt codifying for a polyprotein of 3066 aa and share high nucleotide sequence identity (99,7 % in their complete genome) with respect to PVV-Phureja, recently described in Colombia, but are very divergent with respect to currently available PVV genomes (82-83 %). The genome information was used to design two sets of primers, useful in the specific detection of this virus in S. phureja leaf samples through RT-PCR (459 bp) and RTqPCR (89 bp,. This study underscores the importance of including diagnostics of PVV in S. phureja tuber-seed certification programs in Colombia.

<p>El Potato virus (PVX) es uno de los virus más limitantes del cultivo de la papa en el mundo. Es transmitido solamente por contacto y por tubérculo-semilla. Su control se fundamenta en la siembra de tubérculos certificados por su sanidad viral y en la disponibilidad de metodologías de diagnóstico altamente sensibles. En este trabajo se evaluó la prevalencia del PVX en cuatro diferentes tejidos de tubérculos de Solanum tuberosum subsp. andigena var. Diacol-Capiro y S. phureja var. Criolla Colombia utilizando pruebas de DAS-ELISA para 128 submuestras y de RT-qPCR para 32 grupos de submuestras (4 submuestras/grupo). Los resultados de las pruebas serológicas  indicaron la presencia de PVX en el 6,25 y 50% de las submuestras analizadas para la variedad Diacol-Capiro y Criolla Colombia, respectivamente; mientras que los niveles de prevalencia del PVX utilizando la detección por RT-qPCR fueron del 93,75%, independientemente de la variedad de papa y del tejido evaluado. Los valores promedio del ciclo umbral (Ct) en las RT-qPCR fueron de 25,6 (Ct=18,02 a 34,49) y el análisis de las curvas de desnaturalización permitió identificar dos variantes del virus con valores de Tm de 79,5±1°C y 83,7±1°C. La secuenciación de los amplicones obtenidos por RT-qPCR para los controles positivos y para dos de las muestras, confirmó su naturaleza viral. Estos resultados señalan unos muy altos niveles de prevalencia de PVX en el material de siembra de papa en Antioquia y la necesidad de fortalecer los programas de certificación de semilla con pruebas de detección como RT-qPCR.</p>

Background: Potato virus Y (PVY) is a major pathogen of potatoes with major impact on global agricultural production. Resistance to PVY can be achieved by engineering potatoes to express a recessive, resistant allele of eukaryotic translation initiation factor eIF4E, a host dependency factor essential to PVY replication. Here we analyzed transcriptome changes in eIF4E over-expressing potatoes to shed light on the mechanism underpinning eIF4E-mediated recessive PVY resistance. Results: As anticipated, modified eIF4E-expressing potatoes demonstrated a high level of resistance, eIF4E expression, and an unexpected suppression of the susceptible allele transcript, likely explaining the bulk of the potent antiviral phenotype. In resistant plants, we also detected marked upregulation of genes involved in cell stress responses. Conclusions: Our results reveal a previously unanticipated second layer of signaling attributable to eIF4E regulatory control, and potentially relevant to establishment of a broader, more systematic antiviral host defense.