The stringent response is defined as the physiological changes elicited by amino acid starvation. Many of these changes depend on the regulatory nucleotide ppGpp (guanosine tetraphosphate) synthesized by RelA (ppGpp synthetase I), the relA-encoded protein. The second rel locus of Escherichia coli is called relBE and encodes RelE cytotoxin and RelB antitoxin. RelB counteracts the toxic effect of RelE. In addition, RelB is an autorepressor of relBE transcription. Here we reveal a ppGpp-independent mechanism that reduces the level of translation during amino acid starvation. Artificial overexpression of RelE severely inhibited translation. During amino acid starvation, the presence of relBE caused a significant reduction in the poststarvation level of translation. Concomitantly, relBE transcription was rapidly and strongly induced. Induction of transcription occurred independently of relA and spoT (encoding ppGpp synthetase II), but instead depended on Lon protease. Consistently, Lon was required for degradation of RelB. Replacement of the relBE promoter with a LacI-regulated promoter indicated that strong and ongoing transcription of relBE is required to maintain a proper RelB:RelE ratio during starvation. Thus relBE may be regarded as a previously uncharacterized type of stress-response element that reduces the global level of translation during nutritional stress.starvation ͉ activation of transcription ͉ relE ͉ relB

The intermolecular contact regions between monomers of the homodimeric DNA binding protein ParR and the interaction between the glycoproteins CD28 and CD80 were investigated using a strategy that combined chemical crosslinking with differential MALDI-MS analyses. ParR dimers were modified in vitro with the thiol-cleavable cross-linker 3,39-dithio-bis~succinimidylproprionate!~DTSSP!, proteolytically digested with trypsin and analyzed by MALDI-MS peptide mapping. Comparison of the peptide maps obtained from digested cross-linked ParR dimers in the presence and absence of a thiol reagent strongly supported a "head-to-tail" arrangement of the monomers in the dimeric complex. Glycoprotein fusion constructs CD28-IgG and CD80-F ab were cross-linked in vitro by DTSSP, characterized by nonreducing SDS-PAGE, digested in situ with trypsin and analyzed by MALDI-MS peptide mapping~6 thiol reagent!. The data revealed the presence of an intermolecular cross-link between the receptor regions of the glycoprotein constructs, as well as a number of unexpected but nonetheless specific interactions between the fusion domains of CD28-IgG and the receptor domain of CD80-F ab . The strategy of chemical cross-linking combined with differential MALDI-MS peptide mapping~6 thiol reagent! enabled localization of the interface region~s! of the complexes studied and clearly demonstrates the utility of such an approach to obtain structural information on interacting noncovalent complexes.

The paper examines how Western consumers ideologically and culturally construct edibility, and discusses how this affects household food waste. Consumers' enactments of food waste range from hedonist to altruist ideologies, anchored in a continuum ranging from "disgust" to "duty" and "respect." Furthermore, consumers' categorizations of food as edible or not depend on their self-enactment of competency, leading to internalization or objectification of such assessments. Finally, across altruistic and hedonistic ideologies, interviewees use procrastination in order to reduce feelings of guilt when throwing away food.Marie Mikkelsen is a PhD student at Aalborg University with a master of arts in culture, communication and globalization. Her research centers on consumer studies, food waste from a consumer perspective and consumer culture.

Freedom is a widely discussed and highly elusive concept, and has long been represented in exoticised, masculinised and individualised discourses. Freedom is often exemplified through the image of a solitary male explorer leaving the female space of home and familiarity and going to remote places of the world. Through in-situ interviews with families caravanning in Denmark, the primary aim of this study is to challenge existing dominant discourses surrounding the subject of freedom within leisure and tourism studies. Secondly, we shed further light on an under-researched medium of mobility, that of domestic caravanning. This serves to not only disrupt representations of freedom as occurring through exoticised, masculinised and individualised practices, but to give attention to the domestic, banal contexts where the everyday and tourism intersect, which are often overlooked. This novel repositioning opens up new avenues in tourism studies for critical research into the geographies of freedom in mundane, everyday contexts.

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