The availability of limiting resources can potentially influence the intensity of intra- and interspecific interactions. Stranded macroalgae exported from adjacent coastal ecosystems supports ...abundant intertidal consumers on oceanic sandy beaches, including talitrid amphipods, which can be one of the numerically dominant invertebrates of the upper shore. The allochthonous nature of this donor-controlled food subsidy and its unpredictable delivery by waves and currents, results in highly variable and potentially limiting resource availability for these consumers. In Chile, adults of the talitrid amphipod,
Orchestoidea tuberculata Nicolet, can influence the survival of juvenile conspecifics through cannibalism, a type of intraspecific interaction we hypothesized could be affected by the availability of macroalgal resources. We experimentally investigated the potential influence of food availability on cannibalism between age classes in
O. tuberculata in laboratory mesocosms. Juvenile mortality in presence of conspecific adults was significantly higher when juveniles and adults were maintained without food. However, adult mortality was neither density dependent or food dependent. Further, juveniles did not influence adult mortality, either with or without food. The strong effect of food limitation on juvenile mortality from cannibalism by adults of
O. tuberculata found here, supports our hypothesis that food resource availability on beaches can affect this intraspecific interactions. In addition these results provide evidence of the potential importance of biological interaction in the population dynamics of intertidal consumers on oceanic sandy beaches.
Este artículo es producto de la revisión bibliográfica y de reflexiones surgidas acerca de esta con nuestros alumnos en la Cátedra de Historia de las Ideas y Movimientos Sociales Contemporáneos, ...dictada en la Escuela de Estudios Políticos y Administrativos de la Universidad Central de Venezuela: al comprobar en las lecturas que no hay una precisión conceptual que permita definir qué realmente se entiende por movimiento social, ante las diferentes interpretaciones que del concepto se observan, así como del exagerado uso de la idea para calificar las diferentes manifestaciones sociales que han tenido lugar en Venezuela, España y otras partes del mundo en estos últimos tiempos, lo que genera confusión para identificar claramente qué es un "movimiento social".
Studies of interfacial processes involving leaching bacteria and sulfide minerals (MS) are necessary to understand and improve the bioleaching processes of mining industries. Interfacial studies of ...the role of extracellular polymeric substances (EPSs) during cell attachment to MS have been restricted mainly to iron-oxidizing bacteria, neglecting interfacial mechanisms associated with the biooxidation of reduced sulfur compounds (e.g., elemental sulfur, S
0); nevertheless the reduced sulfur compounds may affect MS weathering or dissolution. The importance of sulfur-oxidizing microorganisms is evidenced by the fact that S
0 was generally added to promote the growth of
Acidithiobacillus thiooxidans in some bioleaching processes. Preliminary research coupled either epifluorescence and atomic force microscopy (AFM) or Raman spectroscopy and AFM to analyze biofilms of
A. ferrooxidans on pyrite or the surface features of pyrite in biotic and abiotic experiments. Here, we applied the combination of AFM, Raman and principles of epifluorescence for the study of biofilms of the
A. thiooxidans on previously oxidized pyrite. Our results showed that
A. thiooxidans forms a monolayered biofilm, wherein the contact resulted in a strong adhesion force (467
pN) between the cells and the altered surface, perhaps due to an irreversible binding mechanism. The observations strongly suggested an intimate contact stage during the dynamic interfacial mechanisms of S
0 biooxidation on the pyrite surface. During this process, an overproduction of EPS was recorded (ca. 100%), indicating that EPS plays a key role during microorganism/surface interactions.
Prostate cancer (PCa) is the leading cause of male cancer‑associated mortality worldwide. Mortality is associated with metastasis and hormone resistance. Cellular, genetic and molecular mechanisms ...underlying metastatic progression and hormone resistance are poorly understood. Studies have investigated the local effects of gonadotropin‑releasing hormone (GnRH) analogs (used for androgen deprivation treatments) and the presence of the GnRH receptor (GnRH‑R) on PCa cells. Furthermore, cell subpopulations with stem‑like properties, or cancer stem cells, have been isolated and characterized using a cell culture system derived from explants of human prostate tumors. In addition, the development of preclinical orthotopic models of human PCa in a nonobese diabetic/severe combined immunodeficiency mouse model of compromised immunity has enabled the establishment of a reproducible system of metastatic progression in vivo. There is increasing evidence that metastasis is a complex process involving the cooperative actions of different cancer cell subpopulations, in which cancer stem‑like cells would be responsible for the final step of colonizing premetastatic niches. It has been hypothesized that PCa cells with stemness and mesenchymal signatures act cooperatively in metastatic progression and the inhibition of stemness genes, and that overexpression of androgen receptor (AR) and GnRH‑R decreases the rate the metastasis and sensitizes tumors to hormone therapy. The aim of the present review is to analyze the evidence regarding this cooperative process and the possible influence of stem‑like cell phenotypes, AR and GnRH‑R in metastatic progression and hormone resistance. These aspects may represent an important contribution in the understanding of the mechanisms underlying metastasis and hormone resistance in PCa, and potential routes to blocking these processes, enabling the development of novel therapies that would be particularly relevant for patients with metastatic and castration‑resistant PCa.
la migración ha sido abordada desde un enfoque predominantemente espacial que ha descuidado su dimensión temporal, aunque la referencia al futuro ha sido reconocida como un factor expresivo del ...fenómeno en sí. Las aproximaciones que en antropología se concentran en la temporalidad de la migración han advertido recientemente que, en las circunstancias globales contemporáneas, los proyectos migratorios, en particular los de aquellos que migran en condición de irregularidad, parecen signados por la espera y por la suspensión temporal de su resolución. Estos estudios suelen enfocarse en la experiencia del tiempo de los migrantes, sometidos a una cronopolítica condicionada por la gestión burocrática de la migración. En este trabajo, a partir de un abordaje etnográfico desarrollado entre 2012 y 2019 en comunidades indígenas otomí-hñahñu del Valle del Mezquital, región ubicada en el centro de México, sigo las preocupaciones antropológicas por la temporalidad de la migración y la espera, pero me planteo un camino alternativo al que se ha desarrollado en la literatura reciente sobre el tema. Busco entender las maneras múltiples en que se administra el tiempo incierto de la migración desde las comunidades de origen. Planteo que estas y los migrantes coparticipan del proyecto migratorio y sus temporalidades, al implicarse en prácticas concretas para gestionar las ausencias y administrar las esperas. Las comunidades del Valle del Mezquital, que desde finales del siglo pasado experimentaron alta intensidad migratoria hacia Estados Unidos, son en la actualidad comunidades en espera. Una espera que, aunque marcada por la cronopolítica de la migración, no deja de presentificar su promesa de futuro y orientar temporalmente los proyectos migratorios. Palabras clave: espera, esperanza, futuro, gestión de la ausencia, migración, Valle del Mezquital. Migration has been approached from a predominantly spatial focus that has largely neglected its temporal dimension, although the reference to the future has been recognized as an expressive factor of the phenomenon itself. Approaches in anthropology that focus on the temporality of migration have recently warned that, in contemporary global circumstances, migration projects, particularly those of irregular migrants, seem to be marked by waiting and by the temporary suspension of their resolution. Such studies tend to emphasize the migrants' experience of time, subjected to a chronopolitics conditioned by the bureaucratic management of migration. In this paper, based on an ethnographic approach developed between 2012 and 2019 in Otomi-Hnahnu indigenous communities in the Mezquital Valley, in central Mexico, I follow anthropological concerns about the temporality of migration and waiting. However, I propose an alternative path to the one that has been developed in recent literature on the subject. At the same time, I explore the multiple ways in which the uncertain time of migration is managed among the communities of origin. I propose that these migrants co-participate in the migration project and its temporalities, by engaging in concrete practices to manage absence and waiting times. The Mezquital Valley communities, which have experienced intense migration to the United States since the end of the last century, are currently communities in waiting. A wait that, although marked by the chronopolitics of migration, does not cease to identify its promise for the future and temporarily steer migratory projects. Keywords: Absence management, future, hope, migration, Valle del Mezquital, waiting. a migração vem sendo tratada a partir de uma abordagem predominantemente espacial que tem descuidado de sua dimensão temporal, embora a referência ao futuro seja reconhecida como um fator expressivo do fenômeno em si. As aproximações que em Antropologia estão focadas na temporalidade da migração alertam recentemente que, nas circunstâncias globais contemporâneas, os projetos migratórios, em particular daqueles que migram em condições de irregularidade, parecem marcados pela espera e pela suspensão temporal de sua resolução. Esses estudos costumam se centralizar na experiência do tempo dos migrantes, submetidos a uma cronopolítica condicionada pela gestão burocrática da migração. Neste trabalho, sob uma abordagem etnográfica desenvolvida entre 2012 e 2019 em comunidades indígenas otomí-hnahnu do Valle del Mezquital, localizado no centro do México, sigo as preocupações antropológicas pela temporalidade da migração e da espera, mas me proponho um caminho alternativo ao que a literatura recente sobre o tema vem se desenvolvendo. Procuro entender as maneiras múltiplas nas quais o tempo incerto da migração é controlado a partir das comunidades de origem. Proponho que estas e os migrantes coparticipam do projeto migratório e de suas temporalidades, ao estar implicados em práticas concretas para gerir ausências e esperas. As comunidades do otomí-hnahnu del Valle del Mezquital, que, desde final do século pasado, experimentam alta intensidade migratória aos Estados Unidos, são, na atualidade, comunidades em espera. Uma espera que, embora marcada pela cronopolítica da migração, não deixa de presentificar sua promessa de futuro e orientar temporalmente os projetos migratórios. Palavras-chave: espera, esperança, futuro, gestão da ausência, migração, Valle del Mezquital.
Migration has been approached from a predominantly spatial focus that has largely neglected its temporal dimension, although the reference to the future has been recognized as an expressive factor of ...the phenomenon itself. Approaches in anthropology that focus on the temporality of migration have recently warned that, in contemporary global circumstances, migration projects, particularly those of irregular migrants, seem to be marked by waiting and by the temporary suspension of their resolution. Such studies tend to emphasize the migrants’ experience of time, subjected to a chronopolitics conditioned by the bureaucratic management of migration. In this paper, based on an ethnographic approach developed between 2012 and 2019 in Otomí-Hñahñu indigenous communities in the Mezquital Valley, in central Mexico, I follow anthropological concerns about the temporality of migration and waiting. However, I propose an alternative path to the one that has been developed in recent literature on the subject. At the same time, I explore the multiple ways in which the uncertain time of migration is managed among the communities of origin. I propose that these migrants co-participate in the migration project and its temporalities, by engaging in concrete practices to manage absence and waiting times. The Mezquital Valley communities, which have experienced intense migration to the United States since the end of the last century, are currently communities in waiting. A wait that, although marked by the chronopolitics of migration, does not cease to identify its promise for the future and temporarily steer migratory projects.
One of the factors promoting tumoral progress is the abnormal activation of the epithelial-mesenchymal transition (EMT) program which has been associated with chemoresistance in tumoral cells. The ...transcription factor zinc finger E-box-binding homeobox 1 (ZEB1), a key EMT activator, has recently been related to docetaxel resistance, the main chemotherapeutic used in advanced prostate cancer treatment. The mechanisms involved in this protective effect are still unclear. In a previous work, we demonstrated that ZEB1 expression induced an EMT-like phenotype in prostate cancer cell lines. In this work, we used prostate cancer cell lines 22Rv1 and DU145 to study the effect of ZEB1 modulation on docetaxel resistance and its possible mechanisms. The results showed that ZEB1 overexpression conferred to 22Rv1 cell resistance to docetaxel while its silencing made DU145 cells more sensitive to it. Analysis of resistance markers showed no presence of ATP-binding cassette subfamily B member 1 (MDR1) and no changes in breast cancer resistance protein (BCRP) or ATP-binding cassette subfamily C member 10 (MRP7). However, a correlation between ZEB1, multidrug resistance-associated protein 1 (MRP1), and ATP-binding cassette subfamily C member 4 (MRP4) expression was observed. MRP4 inhibition, using MK571, resensitized cells with ZEB1 overexpression to docetaxel treatment. In addition, modulation of ZEB1 and subsequent change in MRP4 expression correlated with a lower apoptotic response to docetaxel, characterized by lower B-cell lymphoma 2 (Bcl2), high BCL2-associated X protein (Bax), and high active caspase 3 expression. The response to docetaxel in our model seems to be mediated mainly by activation of the apoptotic death program. Our results showed that modulation of MRP4 could be a mediator of ZEB1-related resistance to docetaxel in prostate cancer, making it a possible marker for chemotherapy response in patients who do not express MDR1.
The metabolic and water evaporation strategies in spiders may be part of a set of physiological adaptations to tolerate low or unpredictable food availability, buffering spiders against environmental ...fluctuations such as those of the high mountains of the central Andes. The aim of this study is to analyze experimentally the variations in metabolic rate and the rate of evaporative water with food and/or water restriction in a high mountain mygalomorph spider population (Paraphysa sp.). We found that the low metabolism of this spider was not affected by water restriction, but its metabolism was depressed after 3 weeks of food deprivation. The spider did not show seasonal metabolic changes but it presented seasonal changes in the rate of evaporative water loss at high temperatures. Females with egg sacs reduced their metabolic rate and evaporative water at high temperatures. These findings constitute a set of possible adaptations to a highly fluctuating Mediterranean environment, which is completely covered with snow for many months and then progresses rapidly to a very dry climate with high temperatures.
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