Collective cell durotaxis emerges from long-range intercellular force transmission

The ability of cells to follow gradients of extracellular matrix stiffness—durotaxis—has been implicated in development, fibrosis, and cancer. Here, we found multicellular clusters that exhibited durotaxis even if isolated constituent cells did not. This emergent mode of directed collective cell migration applied to a variety of epithelial cell types, required the action of myosin motors, and originated from supracellular transmission of contractile physical forces. To explain the observed phenomenology, we developed a generalized clutch model in which local stick-slip dynamics of cell-matrix adhesions was integrated to the tissue level through cell-cell junctions. Collective durotaxis is far more efficient than single-cell durotaxis; it thus emerges as a robust mechanism to direct cell migration during development, wound healing, and collective cancer cell invasion.Peer ReviewedPostprint (author's final draft

Variability in the extreme helium star LSS 5121

We report a photometric and spectroscopic study of the hot extreme helium star LSS 5121. We found photometric variability, but no period was evident in its periodogram. This is consistent with the previous proposal, based on spectral line variations, that LSS 5121 is a non-radial pulsator similar to other hot extreme helium stars.Comment: 5 pages, 6 figure

A comparative analysis of the sustainability of rice cultivation technologies using the analytic network process

Abstract Sustainability of local farming systems and technologies is a very important issue that faces notorious measurement difficulties. Multi-criteria methods may help researchers to solve empirical problems in the construction of composite sustainability indicators and in ranking agricultural technologies according to their sustainability. This paper shows how a multi-criteria decision-making technique, the Analytic Network Process (ANP), can be fruitfully employed to this end. Contrary to simpler and hierarchical goal-criteria-alternative approaches, in ANP all the elements in the network can be related in any possible way, which means that a network can incorporate feedback and interdependent relationships within and between clusters. We illustrate the use of ANP by ranking three rice cultivation technologies -that we call unrestricted traditional, agro-environmental and ecological-in the rice fields of the Albufera Natural Park in Valencia (Spain), using economic, environmental and socio-cultural sustainability criteria. Rice is a multifunctional crop in this area, as flooded rice fields act as semi-natural wetlands, with important ecological consequences, mainly connected with the protection of biodiversity. We show that the ANP methodology is perfectly suited to tackling the complex interrelations involved in sustainability evaluation in this case. We find the ecological cultivation system to be the most sustainable technology. The agro-environmental system ranks second, while the unrestricted system is ranked third. Our results also show that if only the economic dimension of sustainability were considered, the order would be reversed, with traditional unrestricted and ecological technologies exchanging places and the agro-environmental system remaining in second place. Additional key words: biodiversity protection, ecosystems, multi-criteria decision methods, ranking of technologies. Resumen Análisis comparativo de la sostenibilidad de tecnologías de cultivo del arroz mediante el método ANP (analytic network process) La sostenibilidad de los sistemas y tecnologías agrícolas locales es un tema que encara notables dificultades de medición. Los métodos multicriterio pueden ayudar a los investigadores en la construcción de indicadores agregados de sostenibilidad y en la ordenación de las tecnologías agrícolas de acuerdo con su sostenibilidad. Este trabajo muestra como una técnica de decisión multicriterio, el Analytic Network Process (ANP), puede ser empleada al respecto. Contrariamente a otros enfoques, en el ANP todos los elementos de la red pueden ponerse libremente en relación, lo que permite incorporar relaciones de interdependencia y realimentación. Su uso se ilustra ordenando tres tecnologías de cultivo del arroz -tradicional, agroambiental y ecológica-, en los arrozales del Parque Natural de la Albufera (Valencia), con criterios de sostenibilidad económicos, ambientales y socioculturales, que recogen el carácter multifuncional del cultivo del arroz en esta zona. Los resultados muestran que la metodología ANP permite abordar las complejas interrelaciones implícitas en la evaluación de la sostenibilidad en este caso, y que el sistema de cultivo ecológico es el más sostenible. El sistema agroambiental ocupa el segundo lugar y el sistema sin restricciones el tercero. Señalan también que si solamente se considerara la dimensión económica de la sostenibilidad el orden se revertiría, con las tecnologías tradicional (sin restricciones) y ecológica alternando en sus posiciones y el sistema agroambiental permaneciendo en la segunda posición. Palabras clave adicionales: biodiversidad, ecosistemas, métodos de decisión multicriterio, ranking de tecnologías

Population structure of anisakis simplex (nematoda) in harbor porpoises phocoena phocoena off Denmark

The population structure and habitat selection of Anisakis simplex in 35 harbor porpoises off Denmark are described. The nematodes were collected from the stomach and duodenal ampulla and were categorized as third-stage larvae, fourth-stage larvae, subadults, and adults. The porpoises harbored 8,043 specimens of A. simplex. The proportion of adults and subadults increased with infrapopulation size. The number of development stages across infrapopulations covaried significantly (Kendall's test of concordance). Concordance was higher in hosts with the highest intensities than in those with low and medium intensities. All stages occurred mainly in the forestomach, but this trend was stronger for the adults. Adult and subadult sex ratios did not depart significantly from 1:1. Our data suggested that recruitment and duration of each stage were the main factors accounting for infrapopulation structure. The preference of A. simplex for the forestomach conformed with previous studies, but the narrower distribution of adults relative to other stages might indicate a strategy to enhance mating opportunities. Information on sex ratios of A. simplex is scarce and contradictory. We suggest that the discrepancies might partly reflect differences in categorization criteria and statistical methods.Herreras Belled, Maria Victoria, [email protected] ; Balbuena Diaz-Pines, Juan Antonio, [email protected] ; Aznar Avendaño, Francisco Javier, [email protected] ; Raga Esteve, Juan Antonio, [email protected]

Patient reported upper gastro-intestinal symptoms associated with fractionated image-guided conformal radiotherapy for metastatic spinal cord compression

Background and purpose Palliative radiotherapy is given to sustain or improve quality of life for patients with advanced cancer. Radiotherapy may however result in symptomatic side effects, which may affect the patient negatively. This prospective longitudinal study of 30 patients aimed at investigating the incidence and severity of early toxicity, particularly focusing on dysphagia, esophagitis and mucositis, following fractionated radiotherapy for cervical and thoracic metastatic spinal cord compression (MSCC), as well as determining the relationship between esophageal dose and early upper gastro-intestinal symptoms. Materials and methods Thirty patients receiving radiotherapy of 3Gyx10 for MSCC were included in the study. Patients were assessed for a total of 7 weeks from onset of radiotherapy using the Edmonton Symptom Assessment System (ESAS) questionnaire. Upper gastro-intestinal symptoms and severity were assessed from the tenth and eleventh question section of the ESAS questionnaire of “other problems” and how much this affected them. The relationships between the mean and maximum esophageal doses and incidence of dysphagia, esophagitis or mucositis were estimated and dose response curves determined. Results Eleven patients reported esophageal symptoms (average duration eleven days, range 1–18 days). Incidence of esophageal toxicity in patients treated at Th8 or above was 79 percent, while no patients treated below Th8 reported any symptoms (p < 0.001). Furthermore, 2 out of 3 patients irradiated at the cervical region reported substantial changes in taste sensation. Risk of symptoms correlated with both mean and maximum esophageal dose and may be a useful tool in planning radiotherapy for MSCC, potentially reducing early upper gastro-intestinal toxicity