No abstract

The redox properties of iron make this metal a key participant in oxygen-mediated toxicity. Accordingly, L5178Y (LY) mouse lymphoma cell lines, which display a unique inverse cross-sensitivity to ionizing radiation (IR) and hydrogen peroxide (H2O2), are a suitable model for the study of possible differences in the constitutive control of intracellular iron availability. We report here that the level of iron in the cytosolic labile iron pool (LIP), ie, potentially active in the Fenton reaction, is more than 3-fold higher in IR-resistant, H2O2-sensitive (LY-R) cells than in IR-sensitive, H2O2-resistant (LY-S) cells. This difference is associated with markedly greater content of ferritin H-subunits (H-Ft) in LY-S than in LY-R cells. Our results show that different expression of H-Ft in LY cells is a consequence of an up-regulation of H-Ft mRNA in the LY-S mutant cell line. In contrast, posttranscriptional control of iron metabolism mediated by iron-responsive element–iron regulatory proteins (IRPs) interaction is similar in the 2 cell lines, although IRP1 protein levels in iron-rich LY-R cells are twice those in iron-deficient LY-S cells. In showing that LY cell lines exhibit 2 different patterns of intracellular iron regulation, our results highlight both the role of high LIP in the establishment of pro-oxidant status in mammalian cells and the antioxidant role of ferritin.

Common ground is most often understood as the sum of mutually known beliefs, knowledge, and suppositions among the participants in a conversation. It explains why participants do not mention things that should be obvious to both. In some accounts of communication, reaching a mutual understanding, i.e., broadening the common ground, is posed as the ultimate goal of linguistic interactions. Yet, congruent with the more pragmatic views of linguistic behavior, in which language is treated as social coordination, understanding each other is not the purpose (or not the sole purpose) of linguistic interactions. This purpose is seen as at least twofold (e.g., Fusaroli et al., 2014): to maintain the systemic character of a conversing dyad and to organize it into a functional synergy in the face of tasks posed for a dyadic system as a whole. It seems that the notion of common ground is not sufficient to address the latter character of interaction. In situated communication, in which meaning is created in a distributed way in the very process of interaction, both common (sameness) and privileged (diversity) information must be pooled task-dependently across participants. In this paper, we analyze the definitions of common and privileged ground and propose a conceptual extension that may facilitate a theoretical account of agents that coordinate via linguistic communication. To illustrate the usefulness of this augmented framework, we apply it to one of the recurrent issues in psycholinguistic research, namely the problem of perspective-taking in dialog, and draw conclusions for the broader problem of audience design.