Ionic self-complementarity induces amyloid-like fibril formation in an isolated domain of a plant copper metallochaperone protein

Background  

Arabidopsis thaliana copper metallochaperone CCH is a functional homologue of yeast antioxidant ATX1, involved in cytosolic copper transport. In higher plants, CCH has to be transported to specialised cells through plasmodesmata, being the only metallochaperone reported to date that leaves the cell where it is synthesised. CCH has two different domains, the N-terminal domain conserved among other copper-metallochaperones and a C-terminal domain absent in all the identified non-plant metallochaperones. The aim of the present study was the biochemical and biophysical characterisation of the C-terminal domain of the copper metallochaperone CCH.     

Changes in Composition During Embryo Development of the Gulper Shark,Centrophorus Granulosus (Elasmobranchii,Centrophoridae): An Assessment of Maternal-embryonic Nutritional Relationships

Centrophorus granulosus is a deep sea shark that reproduces through aplacental viviparity. Its fecundity is one of the lowest described with only one embryo in a pregnancy lasting about two years. Its mature ovarian egg reaches one of the largest cellular sizes (> 350g) described for any animal species. A previous report suggested a loss of organic matter during development of about 50% (Ranzi 1932), the highest rate reported for any elasmobranch. We measured the amounts of water, organic and inorganic matter in a complete series of embryos, by drying and later incinerating separately the external yolksac, eviscerated body, internal yolksac, liver and digestive tract. Wet weight of uterine ova ranged from 143.2–370.4g, was positively and significantly correlated with maternal size, and the size of full-term embryos increased with maternal size. A graphical method was developed to allow weight comparison between uterine ova and full-term embryos while taking into account the initial variability in uterine ova size. Total wet weight of the embryo system increased during development by +31/+34%. Changes in percentage composition (from initial values) were: water +99/+101%; organic matter –18/–25%; inorganic matter +114/+170%. The rate of decrease of organic matter was much lower than previously suggested, and was similar to values described for oviparous species. These results suggest that C. granulosus is a strictly lecithotrophic species, with no maternal contribution of organic matter during development, although the female does provide both water and inorganic material. Other factors that might influence the accuracy of this assessment are discussed.     

Energy Intensity of the Catalan Construction Sector

We used a thermodynamic framework to characterize the resource consumption of the construction sector in 2001 in Catalonia, the northeast region of Spain. The analysis was done with a cradle‐to‐product life cycle approach using material flow analysis (MFA) and exergy accounting methodologies to quantify the total material and energy inputs in the sector. The aim was to identify the limitations of resource metabolism in the sector and to pinpoint the opportunities for improved material selection criteria, processing, reuse, and recycling for sustainable resource use. The results obtained from MFA showed that nonrenewables such as minerals and natural rocks, cement and derivatives, ceramics, glass, metals, plastics, paints and other chemicals, electric and lighting products, and bituminous mix products accounted for more than 98% of the input materials in the construction sector. The exergy analysis quantified a total 113.1 petajoules (PJ) of exergy inputs in the sector; utilities accounted for 57% of this exergy. Besides exergy inputs, a total of 6.85 million metric tons of construction and demolition waste was generated in 2001. With a recycling rate of 6.5%, the sector recovered 1.3 PJ of exergy. If the sector were able to recycle 80% of construction and demolition waste, then exergy recovery would be 10.3 PJ. Hence the results of this analysis indicate that improvements are required in manufacturing processes and recycling activities, especially of energy‐intensive materials, in order to reduce the inputs of utilities and the extraction of primary materials from the environment.     

Potassium starvation in yeast: mechanisms of homeostasis revealed by mathematical modeling

The intrinsic ability of cells to adapt to a wide range of environmental conditions is a fundamental process required for survival. Potassium is the most abundant cation in living cells and is required for essential cellular processes, including the regulation of cell volume, pH and protein synthesis. Yeast cells can grow from low micromolar to molar potassium concentrations and utilize sophisticated control mechanisms to keep the internal potassium concentration in a viable range. We developed a mathematical model for Saccharomyces cerevisiae to explore the complex interplay between biophysical forces and molecular regulation facilitating potassium homeostasis. By using a novel inference method ("the reverse tracking algorithm") we predicted and then verified experimentally that the main regulators under conditions of potassium starvation are proton fluxes responding to changes of potassium concentrations. In contrast to the prevailing view, we show that regulation of the main potassium transport systems (Trk1,2 and Nha1) in the plasma membrane is not sufficient to achieve homeostasis.     

A comparative life cycle assessment of two treatment technologies for the Grey Lanaset G textile dye: biodegradation by Trametes versicolor and granular activated carbon adsorption

Purpose

The aim of this study is to use life cycle assessment (LCA) to compare the relative environmental performance of the treatment using Trametes versicolor with a common method such as activated carbon adsorption. This comparison will evaluate potential environmental impacts of the two processes. This work compiles life cycle inventory data for a biological process that may be useful for other emergent biotechnological processes in water and waste management. LCA was performed to evaluate the use of a new technology for the removal of a model metal-complex dye, Grey Lanaset G, from textile wastewater by means of the fungus T. versicolor. This biological treatment was compared with a conventional coal-based activated carbon adsorption treatment to determine which alternative is preferable from an environmental point of view.

Materials and methods

The study is based on experimental research that has tested the novel process at the pilot scale. The analysis of the biological system ranges from the production of the electricity and ingredients required for the growth of the fungus and ends with the composting of the residual biomass from the process. The analysis of the activated carbon system includes the production of the adsorbent material and the electricity needed for the treatment and regeneration of the spent activated carbon. Seven indicators that measure the environmental performance of these technologies are included in the LCA. The indicators used are climate change, ozone depletion, human toxicity, photochemical oxidant formation, terrestial acidification, freshwater eutrophication, marine eutrophication, terrestrial ecotoxicity, freshwater ecotoxicity, marine ecotoxicity, metal depletion and fossil depletion.

Results

The results show that the energy use throughout the biological process, mainly for sterilisation and aeration, accounts for the major environmental impacts with the inoculum sterilisation being the most critical determinant. Nevertheless, the biological treatment has lower impacts than the physicochemical system in six of these indicators when steam is generated directly on site. A low-grade carbon source as an alternative to glucose might contribute to reduce the eutrophication impact of this process.

Conclusions

The LCA shows that the biological treatment process using the fungus T. versicolor to remove Grey Lanaset G offers important environmental advantages in comparison with the traditional activated carbon adsorption method. This study also provides environmental data and an indication of the potential impacts of characteristic processes that may be of interest for other applications in the field of biological waste treatment and wastewater treatment involving white-rot fungi.     

Polymer--drug conjugates as nano-sized medicines

Polymer Therapeutics have enormously evolved in the past decades. Several polymeric drugs as well as polymer-protein conjugates have been in the market since the 90s, but although polymer-drug conjugates are already in clinical trials they still need to reach this final goal. There are four main convergent strategies to move this platform technology further. First, exploitation of new molecular targets in cancer therapy and design of polymer-drug conjugates as treatments for other diseases. Second, the development of combination therapy. Third, attempts to improve polymer chemistry, including the use of new well-defined architectures and the optimization of the advanced characterization techniques essential to transform a promising conjugate into a candidate for clinical evaluation. Finally, increased understanding of polymer conjugate features that govern clinical risk-benefit is leading to an appreciation of clinical biomarkers that will open new possibilities for personalized therapy.     

A functional connection between translation elongation and protein folding at the ribosome exit tunnel in Saccharomyces cerevisiae

Proteostasis needs to be tightly controlled to meet the cellular demand for correctly de novo folded proteins and to avoid protein aggregation. While a coupling between translation rate and co-translational folding, likely involving an interplay between the ribosome and its associated chaperones, clearly appears to exist, the underlying mechanisms and the contribution of ribosomal proteins remain to be explored. The ribosomal protein uL3 contains a long internal loop whose tip region is in close proximity to the ribosomal peptidyl transferase center. Intriguingly, the rpl3[W255C] allele, in which the residue making the closest contact to this catalytic site is mutated, affects diverse aspects of ribosome biogenesis and function. Here, we have uncovered, by performing a synthetic lethal screen with this allele, an unexpected link between translation and the folding of nascent proteins by the ribosome-associated Ssb-RAC chaperone system. Our results reveal that uL3 and Ssb-RAC cooperate to prevent 80S ribosomes from piling up within the 5′ region of mRNAs early on during translation elongation. Together, our study provides compelling in vivo evidence for a functional connection between peptide bond formation at the peptidyl transferase center and chaperone-assisted de novo folding of nascent polypeptides at the solvent-side of the peptide exit tunnel.