Geminiviral protein Rep interferes in PCNA sumoylation

Rep is a multifunctional protein essential for replication of geminivirus that interferes with the sumoylation of a key protein in the DNA replication, PCNA (Proliferating Cell Nuclear Antigen). It is known that Rep is capable of interacting with a plethora of plant proteins, including PCNA. Despite the biological significance remains unknown, it’s thought that this interaction should play a key role for generating new copies of the virus genome. Therefore, in order to characterize this interaction, we study which lysines are sumoylated in tomato PCNA (SlPCNA). Considering conservation, location and presence of sumoylation domain criteria, we have identified some candidate lysines and studied how its mutation affects this protein sumoylation in Escherichia coli assays. Finally, we plan to confirm and characterize the Rep interference on SlPCNA sumoylation and determine if this interference occurs in planta.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Electronic Word-of-Mouth: Impact on Music Sales in the American Market

Internet, today, is a popular communication and feedback sharing platform. Digital content is also readily available over the internet. These two phenomena have propelled the electronic interaction among music consumers to new heights. Our study investigates the contribution of electronic word-of-mouth (eWOM) to the sales of music albums. We studied the American music market for 13 consecutive weeks. The Sales data for these weeks was correlated to the eWOM data for the period mentioned before

Fruit cell culture as a model system to study cell wall changes during strawberry fruit ripening

Strawberry (Fragaria x ananassa, Duch.) fruit is characterized by its fast ripening and soft texture at the ripen stage, resulting in a short postharvest shelf life and high economic losses. It is generally believed that the disassembly of cell walls, the dissolution of the middle lamella and the reduction of cell turgor are the main factors determining the softening of fleshy fruits. In strawberry, several studies indicate that the solubilisation and depolymerisation of pectins, as well as the depolymerisation of xyloglucans, are the main processes occurring during ripening. Functional analyses of genes encoding pectinases such as polygalacturonase and pectate lyase also point out to the pectin fraction as a key factor involved in textural changes. All these studies have been performed with whole fruits, a complex organ containing different tissues that differ in their cell wall composition and undergo ripening at different rates. Cell cultures derived from fruits have been proposed as model systems for the study of several processes occurring during fruit ripening, such as the production of anthocyanin and its regulation by plant hormones. The main objective of this research was to obtain and characterize strawberry cell cultures to evaluate their potential use as a model for the study of the cell wall disassembly process associate with fruit ripening. Cell cultures were obtained from cortical tissue of strawberry fruits, cv. Chandler, at the stages of unripe-green, white and mature-red. Additionally, a cell culture line derived from strawberry leaves was obtained. All cultures were maintained in solid medium supplemented with 2.5 mg.l-1 2,4-D and incubated in the dark. Cell walls from the different callus lines were extracted and fractionated to obtain CDTA and sodium carbonate soluble pectin fractions, which represent polyuronides located in the middle lamella or the primary cell wall, respectively. The amounts of homogalacturonan in both fractions were estimated by ELISA using LM19 and LM20 antibodies, specific against demethylated and methyl-esterified homogalacturonan, respectively. In the CDTA fraction, the cell line from ripe fruit showed a significant lower amount of demethylated pectins than the rest of lines. By contrast, the content of methylated pectins was similar in green- and red-fruit lines, and lower than in white-fruit and leaf lines. In the sodium carbonate pectin fraction, the line from red fruit also showed the lowest amount of pectins. These preliminary results indicate that cell cultures obtained from fruits at different developmental stages differ in their cell wall composition and these differences resemble to some extent the changes that occur during strawberry softening. Experiments are in progress to further characterize cell wall extracts with monoclonal antibodies against other cell wall epitopes.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Nanostructural changes in cell wall pectins during strawberry fruit ripening assessed by atomic force microscopy

Rapid loss of firmness occurs during strawberry (Fragaria × ananassa Duch) ripening, resulting in a short shelf life and high economic losses. The disassembly of cell walls is considered the main responsible for fruit softening, being pectins extensively modified during strawberry ripening (Paniagua et al. 2014). Atomic force microscopy allows the analysis of individual polymer chains at nanostructural level with a minimal sample preparation (Morris et al., 2001). The main objective of this research was to compare pectins of green and red ripe strawberry fruits at the nanostructural level to shed light on structural changes that could be related to softening. Cell walls from strawberry fruits were extracted and fractionated with different solvents to obtain fractions enriched in a specific component. The yield of cell wall material, as well as the amount of the different fractions, decreased in ripe fruits. CDTA and Na2CO3 fractions underwent the largest decrements, being these fractions enriched in pectins supposedly located in the middle lamella and primary cell wall, respectively. Uronic acid content also decreased significantly during ripening in both pectin fractions, but the amount of soluble pectins, those extracted with phenol:acetic acid:water (PAW) and water increased in ripe fruits. Monosaccharide composition in CDTA and Na2CO3 fractions was determined by gas chromatography. In both pectin fractions, the amount of Ara and Gal, the two most abundant carbohydrates, decreased in ripe fruits. The nanostructural characteristics of CDTA and Na2CO3 pectins were analyzed by AFM. Isolated pectic chains present in the CDTA fraction were significantly longer and more branched in samples from green fruits than those present in samples obtained from red fruit. In spite of slight differences in length distributions, Na2CO3 samples from unripe fruits displayed some longer chains at low frequency that were not detected in ripe fruits. Pectin aggregates were more frequently observed in green fruit samples from both fractions. These results support that pectic chain length and the nanostructural complexity of the pectins present in CDTA and Na2CO3 fractions diminish during strawberry fruit development, and these changes, jointly with the loss of neutral sugars, could contribute to the solubilization of pectins and fruit softening. Paniagua et al. (2014). Ann Bot, 114: 1375-1383 Morris et al. (2001). Food Sci Tech 34: 3-10 This research was supported by FEDER EU Funds and the Ministerio de Educación y Ciencia of Spain (grant reference AGL2011-24814)Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

The queen of the island : On the density and distribution of the Eurasian Collared-Dove (Streptopelia decaocto) in Cozumel

The Eurasian Collared-Dove (Streptopelia decaocto) is one of the most successful invasive bird species across the world. Worryingly, the invasive dove is a known reservoir of many diseases, some of which can potentially infect mammals (including human beings). Additionally, aggressive behaviors have been recorded toward other bird species resulting in territory and nest usurpation. Thus, the presence of this species poses an important risk for native species with similar habits, particularly in insular systems. Based on this, we carried out this study to assess the density and distribution of the Eurasian Collared-Dove in the island of Cozumel, as well as to evaluate the relationship between their abundance and the environmental characteristics of the places they inhabit. We estimated their distance-corrected densities in the island's largest town and performed an inverse distance weighting (IDW) interpolation to visualize their distribution. We performed a generalized linear model (GLM) to assess relationships between the environmental variables and the abundance of doves using a reduced model procedure. We obtained 137 records of doves present in 94% of all survey sites and an estimated density of 6.8 ind/ha, for a total of 6,670 doves in San Miguel de Cozumel. We did not find a spatial pattern of the dove's distribution on the urban setting, but we found an interaction between their abundances with tree cover and building height. Our findings, together with previous evidence of infection risk and aggressive behavior, make this species a threat to the native species communities of fragile ecosystems such as the island of Cozumel.Peer reviewe

Unravelling the nanostructure of strawberry fruit pectins by atomic force microscopy

Atomic force microscopy (AFM) allows the analysis of individual polymers at nanostructural level with a minimal sample preparation. This technique has been used to analyse the pectin disassembly process during the ripening and postharvest storage of several fleshy fruits. In general, pectins analysed by AFM are usually visualized as isolated chains, unbranched or with a low number of branchs and, occasionally, as large aggregates. However, the exact nature of these structures is unknown. It has been suggested that pectin aggregates represent a mixture of rhamnonogalacturonan I and homogalacturonan, while isolated chains and their branches are mainly composed by polygalacturonic acid. In order to gain insight into the nature of these structures, sodium carbonate soluble pectins from ripe strawberry (Fragaria x ananassa, Duch.) fruits were subjected to enzymatic digestion with endo-Polygalacturonase M2 from Aspergillus aculeatus, and the samples visualized by AFM at different time intervals. Pectins isolated from control, non-transformed plants, and two transgenic genotypes with low level of expression of ripening-induced pectinase genes encoding a polygalacturonase (APG) or a pectate lyase (APEL) were also included in this study. Before digestion, isolated pectin chains from control were shorter than those from transgenic fruits, showing number-average (LN) contour length values of 73.2 nm vs. 95.9 nm and 91.4 nm in APG and APEL, respectively. The percentage of branched polymers was significantly higher in APG polyuronides than in the remaining genotypes, 33% in APG vs. 6% in control and APEL. As a result of the endo-PG treatment, a gradual decrease in the main backbone length of isolated chains was observed in the three samples. The minimum LN value was reached after 8 h of digestion, being similar in the three genotypes, 22 nm. By contrast, the branches were not visible after 1.5-2 h of digestion. LN values were plotted against digestion time and the data fitted to a first-order exponential decay curve, obtaining R2 values higher than 0.9. The half digestion time calculated with these equations were similar for control and APG pectins, 1.7 h, but significantly higher in APEL, 2.5 h, indicating that these polymer chains were more resistant to endo-PG digestion. Regarding the pectin aggregates, their volumes were estimated and used to calculate LN molecular weights. Before digestion, control and APEL samples showed complexes of similar molecular weights, 1722 kDa, and slightly higher than those observed in APG samples. After endo-PG digestion, size of complexes diminished significantly, reaching similar values in the three pectin samples, around 650 kDa. These results suggest that isolated polymer chains visualized by AFM are formed by a HG domain linked to a shorter polymer resistant to endo-PG digestion, maybe xylogalacturonan or RG-I. The silencing of the pectate lyase gene slightly modified the structure and/or chemical composition of polymer chains making these polyuronides more resistant to enzymatic degradation. Similarly, polygalacturonic acid is one of the main component of the aggregates.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

A task-driven design model for collaborative AmI systems

Proceedings of the CAISE*06 Workshop on Ubiquitous Mobile Information and Collaboration Systems UMICS '06. Luxemburg, June 5-9, 2006.The proceedings of this workshop also appeared in printed version In T. Latour and M. Petit (eds), Proceedings of Workshops and Doctoral Consortium, The 18th International Conference on Advanced Information Systems Engineering - Trusted Information Systems (CAiSE'06), June 5-9, 2006, Presses Universitaires de Namur, 2006, ISBN 2-87037-525.Also published online by CEUR Workshop Proceedings (CEUR-WS.org, ISSN 1613-0073)Ambient intelligence (AmI) is a promising paradigm for humancentred interaction based on mobile and context-aware computing, natural interfaces and collaborative work. AMENITIES (a conceptual and methodological framework based on task-based models) has been specially devised for collaborative systems and is the starting point for a new design proposal for application to AmI systems. This paper proposes a task-based model for designing collaborative AmI systems, which attempts to gather the computational representation of the concepts involved (tasks, laws, etc.) and the relationships between them in order to develop a complete functional environment in relation with the features of AmI systems (collaborative, context-aware, dynamic, proactive, etc.). The research has been applied to an e-learning environment and is implemented using a blackboard model.This research is partially supported by a Spanish R&D Project TIN2004-03140, Ubiquitous Collaborative Adaptive Training (U-CAT)

A design model applied to development of AmI systems

Also published online by CEUR Workshop Proceedings (CEUR-WS.org, ISSN 1613-0073)Proceedings of the I International Conference on Ubiquitous Computing: Applications, Technology and Social Issues Alcalá de Henares, Madrid, Spain, June 7-9, 2006.Ambient intelligence (AmI) represents a promising paradigm for group-centred collaborative interaction with the surrounding environment. The complexity for AmI designs is closely connected with the mechanism for describing their inherent features. What would be interesting is a method which is capable of describing these properties in a straightforward way. Task modelling techniques are a suitable method for AmI systems. This paper describes a new design and implementation proposal for developing AmI systems, starting from the conceptual and methodological frameworks proposed by AMENITIES, a methodology based on task and behaviour models for the study and development of cooperative systems, extending it with inherent AmI features. With respect to the implementation of AmI systems, an intermediate software layer supporting common functional requirements is supplied in order to simplify their development. The overall scheme therefore simplifies the analysis and development of such systems. These features are shown in a case study of a collaborative e-learning AmI systemThis research is partially supported by a Spanish R&D Project TIN2004-03140, Ubiquitous Collaborative Adaptive Training (U-CAT)

Development of ambient intelligence systems based on collaborative task models

So far, the Ambient Intelligence (AmI) paradigm has been applied to the development of a great variety of real systems. They use advanced technologies such as ubiquitous computing, natural interaction and active spaces, which become part of social environments. In the design of AmI systems, the inherent collaboration among users (with the purpose of achieving common goals) is usually represented and treated in an ad-hoc manner. However, the development of this kind of systems can take advantage of rich design models which embrace concepts in the domain of collaborative systems in order to provide the adequate support for explicit or implicit collaboration. Thereby, relevant requirements to be satisfied, such as an effective coordination of human activities by means of task scheduling, demand to dynamically manage and provide group- and context-awareness information. This paper addresses the integration of both proactive and collaborative aspects into a unique design model for the development of AmI systems; in particular, the proposal has been applied to a learning system. Furthermore, the implementation of this system is based on a blackboardbased architecture, which provides a well-defined high-level interface to the physical layer.This research is partially supported by a Spanish R&D Project TIN2004-03140, Ubiquitous Collaborative Adaptive Training (U-CAT)