Role of boundary conditions in an experimental model of epithelial wound healing

Coordinated cell movements in epithelial layers are essential for proper tissue morphogenesis and homeostasis, but our understanding of the mechanisms that coordinate the behavior of multiple cells in these processes is far from complete. Recent experiments with Madin-Darby canine kidney epithelial monolayers revealed a wave-like pattern of injury-induced MAPK activation and showed that it is essential for collective cell migration after wounding. To investigate the effects of the different aspects of wounding on cell sheet migration, we engineered a system that allowed us to dissect the classic wound healing assay. We studied Madin-Darby canine kidney sheet migration under three different conditions: 1) the classic wound healing assay, 2) empty space induction, where a confluent monolayer is grown adjacent to a slab of polydimethylsiloxane and the monolayer is not injured but allowed to migrate upon removal of the slab, and 3) injury via polydimethylsiloxane membrane peel-off, where an injured monolayer migrates onto plain tissue culture surface, as in the case of empty space induction allowing for direct comparison. By tracking the motion of individual cells within the sheet under these three conditions, we show how the dynamics of the individual cells' motion is responsible for the coordinated migration of the sheet and is coordinated with the activation of ERK1/2 MAPK. In addition, we demonstrate that the propagation of the waves of MAPK activation depends on the generation of reactive oxygen species at the wound edge.     

Gender and ethnicity in the Zionist nation-building project: the case of Hannah Helena Thon

According to Nira Yuval-Davis some of the most important ways in which women are involved in national projects concern their capacity as biological and cultural reproducers of the nation and guardians of its boundaries. In this article I argue that Jewish women in Mandate Palestine not only guarded and reproduced national boundaries, but also redefined them. Middle-class women's organizations acted as agents of ‘nationalization’ and westernization among Mizrahi (lit. Oriental) Jewish communities, who were largely excluded from the imagined community of the nation by Ashkenazi Zionists. I explain the conjunction of gender and ethnicity in the Zionist nation-building project through the life and letters of journalist and social activist Hannah Helena Thon. Two main factors serve as an explanation: the countries from which the leaders of the organizations emerged and their traditions of social work; and the position of middle-class women in the Jewish social field.     

The role of the amygdala in signaling prospective outcome of choice

Can brain activity reveal a covert choice? Making a choice often evokes distinct emotions that accompany decision processes. Amygdala has been implicated in choice behavior that is guided by a prospective negative outcome. However, its specific involvement in emotional versus cognitive processing of choice behavior has been a subject of controversy. In this study, the human amygdala was monitored by functional magnetic resonance imaging (fMRI) while subjects were playing in a naturalistic choice paradigm against the experimenter. In order to win, players had to occasionally choose to bluff their opponent, risk "getting caught," and suffer a loss. A critical period, when choice has been made but outcome was still unknown, activated the amygdala preferentially following the choice that entailed risk of loss. Thus, the response of the amygdala differentiated between subject's covert choice of either playing fair or foul. These results support a role of the amygdala in choice behavior, both in the appraisal of inherent value of choice and the signaling of prospective negative outcomes.     

A secreted lipolytic enzyme from Xanthomonas campestris pv. vesicatoria is expressed in planta and contributes to its virulence

A recombinase-based in vivo expression technology (RIVET) approach with Xanthomonas campestris pv. vesicatoria (Xcv) revealed that lipA, annotated as putative secreted lipase, is expressed during the interaction between this pathogen and tomato. Here, the tnpR and uidA reporter genes were used to show that lipA is strongly induced in XVM2 minimal medium and during the early stages of tomato infection by Xcv. A mutant strain impaired in lipA was generated by insertional mutagenesis. This mutant grew in a similar manner to the wild-type in rich medium, but its growth was significantly compromised in a medium containing olive oil as a single carbon source. The lipolytic activity of the extracellular fraction of the lipA mutant was reduced significantly relative to that of the wild-type strain, thus confirming that lipA indeed encodes a functional secreted enzyme with lipolytic activity. A plasmid carrying a wild-type copy of lipA complemented the lipA mutant for extracellular lipolytic activity. Dip inoculation experiments with tomato lines Hawaii 7998 (H7998) and Micro Tom showed that the lipA mutant grew to a lesser extent than the wild-type in tomato leaves. Following leaf syringe infiltrations, the mutant strain induced disease symptoms that were less severe than those induced by the wild-type strain, supporting a significant role of lipA in the pathogenicity of Xcv.     

Chronic pancreatitis, pancreatic adenocarcinoma and the black box in-between

Pancreatic cancer is a challenging disease for patients, doctors and researchers who for decades have searched for a cure for this deadly malignancy. Although existing mouse models of pancreatic cancer have shed light on the mechanistic basis of the neoplastic conversion of the pancreas, their impact in terms of offering new diagnostics and therapeutic modalities remains limited. Chronic pancreatitis is an inflammatory disease of the pancreas that is associated with a gradual damage of the organ and an increased risk of developing neoplastic lesions. In this review, we propose that detailed studies of chronic inflammatory processes in the pancreas will provide insights into the evolution of pancreatic cancer. This information may prove useful in the design of effective therapeutic strategies to battle the disease.