The C terminus of p53 family proteins is a cell fate determinant

The p53 tumor suppressor is the most commonly mutated gene in human cancers. The ability of p53 to induce cell cycle arrest, apoptosis, DNA repair, and other p53-dependent activities is well known; however, the mechanism by which p53 induces a specific activity over another is unclear. Here, we showed that stringent regulation of and by p53 family isoforms facilitates differential target gene expression and thus determines cell fate. Through the use of engineered deletion mutants, we found that activation domain 2 is required for induction of the proapoptotic target gene insulin-like growth factor binding protein 3 (IGFBP3) by p53 and that the basic domain inhibits induction of this gene by p53. Thus, for the first time we provide evidence that the basic domain of p53 is inhibitory in vivo as has been determined in vitro. We also showed that the in vivo inhibitory activity of the basic domain depends upon activation domain 1, such that combined deletion of activation domain 1 and the basic domain was required to alleviate the inhibition by the basic domain. Importantly, deletion of the inhibitory functional domains, namely N-terminal activation domain 1 and the C-terminal basic domain, is paralleled in nature. We found that the IGFBP3 promoter was activated by p53(DeltaNDeltaBD), which mimics a naturally occurring N- and C-terminally truncated human p53 isoform, and by p53AS, a C-terminally truncated murine p53 isoform generated through alternative splicing, but not by full-length human or murine p53. In addition, we found that the C termini of p63 and p73 inhibit the induction of IGFBP3, such that C-terminally truncated p63 and p73 isoforms induce the expression of IGFBP3, whereas full-length ones cannot. We also demonstrated that IGFBP3 is an important effector of the apoptosis induced by N- and C-terminally truncated p53, such that knockdown of IGFBP3 by using an IGFBP3 neutralizing antibody or IGFBP3 small interfering RNA partially rescues the cell death induced by N- and C-terminally truncated p53. In addition, we identified that histone deacetylase activity, not p53 DNA binding ability, governs the regulation of IGFBP3 by full-length p53 family proteins, as inhibition of histone deacetylases restores the induction of IGFBP3 by exogenous full-length p53, p63, and p73 proteins. Furthermore, we found that activation of p53 or inhibition of histone deacetylases alone was not sufficient to induce IGFBP3; however, combined treatment endowed endogenous p53 with this activity. To better understand the significance of this regulation, we performed a microarray study and identified several target genes differentially regulated by full-length p53 and p53 lacking the N-terminal activation domain 1 and the C-terminal basic domain. Taken together, our data suggest a novel mechanism by which p53 family proteins differentially regulate gene expression and provide an insight for designing a combined therapy for cancer treatment.     

Pattern of enzymes involved in cyanogenesis and HCN metabolism in cell cultures of Phaseolus lunatus L. varieties

Callus and cell suspension cultures were established from root and shoot tips of aseptically-grown seedlings of highly cyanogenic Phaseolus lunatus L. varieties. The content of cyanogenic glucosides in the explanted seedling sections decreased during storage, the derived callus cells were free of cyanogenic glycosides. In spite of the non-existence of cyanogenic glucosides, the cyanogen degrading linamarase, the cyanide detoxifying enzyme -cyanoalanine synthase and also hydroxynitrile lyase were still present in suspension cultures. The linamarase activity equalled the total -glucosidase activity, of which up to 80% was found in the culture medium. In contrast the -cyanoalanine synthase and the hydroxy nitrile lyase were entirely localized in the cell biomass.~Botanical Institute, Technical University Braunschweig     

Phosphorus Enhances Uptake of Dissolved Organic Matter in Boreal Streams

Retention of carbon (C), either by physical mechanisms or microbial uptake, is a key driver of the transformation and storage of C and nutrients within ecosystems. Both the molecular composition and nutrient content of organic matter influence the rate at which it is retained in streams, but the relative influence of these characteristics remains unclear. We estimated the effects of nutrient content and molecular composition of dissolved organic C (DOC) on uptake in boreal streams by measuring rates of C retention, in situ, following introduction of leachates derived from alder, poplar, and spruce trees subject to long-term fertilization with nitrogen (N) or phosphorus (P). Leachate C:N varied approximately twofold, and C:P varied nearly 20-fold across species and nutrient treatments. Uptake of DOC was greatest for leachates derived from trees that had been fertilized with P, a finding consistent with P-limitation of uptake and/or preferential sorption of P-containing molecules. Optical measures indicated that leachates derived from the three tree species varied in molecular composition, but uptake of DOC did not differ across species, suggesting weak constraints on retention imposed by molecular composition relative to nutrient limitation. Observed coupling between P and C cycles highlights the potential for increased P availability to enhance DOC retention in headwater streams.     

Cultural evolution and the variable phenotype

It is common in attempts to extend the theory of evolution to culture to generalize from the causal basis of biological evolution, so that evolutionary theory becomes the theory of copying processes. Generalizing from the formal dynamics of evolution allows greater leeway in what kinds of things cultural entities can be, if they are to evolve. By understanding the phenomenon of cultural transmission in terms of coordinated phenotypic variability, we can have a theory of cultural evolution which allows us to avoid the various difficulties with the elaboration of informational entities such as the cultural replicator, or meme. Such an account is a boon to the project of evolutionary epistemology since it confirms the presumption in favor of the general adaptiveness of culture, illuminating rather than obscuring the inherent intimacy of our relationship to (e.g.) our ideas.     

Bioavailability of Sorbed 3-Chlorodibenzofuran

One of the main factors impeding the bioremediation of polluted soils, sediments, and aquifers is the low bioavailability of chemicals which are sorbed by organic matter. To obtain more insight into the factors that control the degradation of sorbed compounds, we used a defined model system in which 3-chlorodibenzofuran (3CDF) was the organic contaminant, porous Teflon granules were the sorbent, and Sphingomonas sp. strain HH19k was the test organism. The sorption of 3CDF to Teflon reached equilibrium within 150 min. The curved shape of the sorption isotherm, the extent of sorption, and the desorption kinetics suggested that there was a surface interaction (adsorption) between 3CDF and Teflon which took place mainly inside the pores of the granules. The kinetics of desorption could be ascribed to sorption-retarded radial diffusion inside the granules since the desorption rate not only was correlated with the sorbed-phase concentration, but also depended on the equilibration status of sorption, since (i) the high initial desorption rate sharply declined because of the depletion of 3CDF in the outermost parts of the granules, but high rates were observed again after the system had been given time to reequilibrate, and (ii) the initial desorption rate was higher when the preceding contact time between sorbate and sorbent was shorter (i.e., most 3CDF was still located in the exterior parts of the granules). These characteristics were observed irrespective of whether the desorption was driven by percolating water through the sorbent or by attaching active bacteria to the sorbent. 3CDF consumption by attached cells drove 3CDF desorption to a considerable extent. The attached cells were thus efficiently supplied with desorbing 3CDF. On the basis of our results, we propose that the rate at which a sorbed substrate becomes available for organisms is influenced by (i) the specific affinity of the degrading organisms (i.e., their ability to reduce the aqueous substrate concentration) and (ii) the tendency of the organisms to adhere to the sorbent.     

Willingness to Pay for Eco‐Certified Refurbished Products: The Effects of Environmental Attitudes and Knowledge

Refurbishing products, which are increasingly sold in business‐to‐consumer markets, is a key strategy to reduce waste. Nevertheless, research finds that consumers’ willingness to pay (WTP) for refurbished products is low. Strategies for a higher WTP are needed in order to grow consumer markets for refurbished products. Eco‐certification of refurbished products may be a key strategy here. Drawing on the consumer WTP literature concerning “green” products, we investigate the impact of independent eco‐certificates. Our analysis is based on a survey of 231 potential customers. The results suggest that, across various product categories, the WTP for products with refurbished components is significantly lower. Adding an eco‐certificate tends to return the WTP toward the virgin product level. We show that consumers with proenvironmental attitudes particularly exhibit green buying behavior. Our findings indicate that eco‐certification is often worthwhile because it enhances the business rationale for producing products with refurbished components.     

Biodegradation of 4-nitroanisole by two Rhodococcus spp.

Two Rhodococcus strains, R. opacus strain AS2 and R. erythropolis strain AS3, that were able to use 4-nitroanisole as the sole source of carbon and energy, were isolated from environmental samples. The first step of the degradation involved the O-demethylation of 4-nitroanisole to 4-nitrophenol which accumulated transiently in the medium during growth. Oxygen uptake experiments indicated the transformation of 4-nitrophenol to 4-nitrocatechol and 1,2,4-trihydroxybenzene prior to ring cleavage and then subsequent mineralization. The nitro group was removed as nitrite, which accumulated in the medium in stoichiometric amounts. In R. opacus strain AS2 small amounts of hydroquinone were produced by a side reaction, but were not further degraded.     

Glycosyl receptors in macrophage subpopulations of rat spleen and lymph node

Summary We have developed an immunohistochemical method for the in vivo and in vitro detection of glycosyl receptors in rat spleen and lymph nodes by using neoglycoproteins. The receptor in both organs recognized mannose coupled to bovine serum albumin (mannose-BSA), fuscose-BSA, N-acetylglucosamine-BSA and to a lesser extent glucose-BSA, but not galactose-BSA or N-acetylgalactosamine-BSA. In vitro neoglycoprotein-receptor binding was Ca²⁺ dependent and could be inhibited by mannan but not by mannose. Simultaneous staining with the monoclonal antibodies ED1, ED2 or ED3 revealed that only ED1-and ED3-positive macrophages were involved in the binding of neoglycoproteins. In the spleen, the marginal-zone macrophages and a subpopulation of the marginal metallophils possess glycosylbinding receptors. In the lymph nodes, the medullary sinus macrophages and a subpopulation of the outercortex macrophages are able to bind neoglycoproteins.