Assessment of ecological sustainability of a building subjected to potential seismic events during its lifetime

Purpose

Sustainable development aims to enhance the quality of life by improving the social, economic and environmental conditions for present and future generations. A sustainable engineering decision-making strategy for design and assessment of construction works (i.e., civil engineering and buildings) should take into account considerations regarding the society, the economy and the environment. This study presents a novel approach for the life cycle assessment (LCA) of a case-study building subjected to seismic actions during its service life, accounting for structural reliability.

Methods

A methodology is presented that evaluates the time-dependent probability of exceeding a limit state considering the uncertainty in the representation of seismic action. By employing this methodology, the earthquake-induced damages are related to the environmental and social losses caused by the occurrence of the earthquake. A LCA of a case-study building accounting for the time-dependent seismic reliability is conducted using a damage-oriented LCA approach.

Results and discussion

The contributions of the different life cycle phases to the total environmental impact related to the building lifetime are in agreement with previous results in this field of study. However, the LCA results revealed significant risk-based contributions for the rehabilitation phase due to the induced damage resulting in seismic events. Particularly, the rehabilitation phase is expected to contribute to the total environmental impact with around the 25 % of the initial environmental impact load (related to the pre-use phase) as a consequence of seismic damage.

Conclusions and recommendations

The probability of occurrence of seismic events affects the LCA results for various life cycle phases of a building in terms of all the indicators adopted in the analysis. The time-dependent probability of collapse in a year can represent a benchmark indicator for human safety in the context of social sustainability for the building sector. The proposed approach can be implemented in a sustainable decision-making tool for design and assessment.     

The intracellular region of Notch ligands: does the tail make the difference?

   

The cytoplasmic tail of Notch ligands drives endocytosis, mediates association with proteins implicated in the organization of cell-cell junctions and, through regulated intra-membrane proteolysis, is released from the membrane as a signaling fragment. We survey these findings and discuss the role of Notch ligands intracellular region in bidirectional signaling and possibly in signal modulation in mammals.     

Mutational studies of Pa-AGOG DNA glycosylase from the hyperthermophilic crenarchaeon Pyrobaculum aerophilum

In all organisms studied to date, 8-oxoguanine (GO), an important oxidation product of guanine, is removed by highly conserved GO DNA glycosylases. The hyperthermophilic crenarchaeon Pyrobaculum aerophilum encodes a GO DNA glycosylase, Pa-AGOG (Archaeal GO DNA glycosylase) which has become the founding member of a new family within the HhH-GPD superfamily of DNA glycosylases based on unique structural and functional characteristics. In this study, we made quantitative measurements of the DNA glycosylase activity of Pa-AGOG wild type and some engineered variants under single turnover conditions. The mutagenesis study includes residues Trp222 (W222A and W222F), Trp69 (W69F), Gln31 (Q31S) and Lys147 (K147Q) all of which are involved in GO recognition and Asp172 (D172N and D172Q) and Lys140 (K140Q) that are involved in catalysis. Pa-AGOG prefers GO/G mispairs for both base excision and base excision/β-lyase activities. The mutagenesis studies show that base-stacking between GO and Trp222 is very important for recognition. The contact between Trp69 and the 8-oxo group was found to be dispensable, while that to N⁷ by Gln31 is indispensable for GO recognition. In contrast to human OGG1 the catalytic mutant, D172Q did not show detectable glycosylase activity. Pa-AGOG mutants K140Q, D172N and D172Q did bind GO containing single-stranded DNA more tightly than double-stranded DNA containing a GO/C base pair. Our studies confirm and extend the unique characteristics of Pa-AGOG, which distinguish it from other mesophilic and thermostable GO DNA glycosylases.     

Genetic variability of the stolbur phytoplasma vmp1 gene in grapevines,bindweeds and vegetables

Aim: Evaluation of the genetic variability of stolbur phytoplasma infecting grapevines, bindweeds and vegetables, collected in different central and southern Italian regions. Materials and Results: Phytoplasma isolates belonging to stolbur subgroup 16SrXII‐A were subjected to molecular characterization by polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP), to investigate two different nonribosomal genes: tuf and vmp1. In grapevines, 32% of samples were infected by tuf‐a type and 68% by tuf‐b type, with different relative incidences in the regions surveyed. All herbaceous samples (bindweeds, tomato, tobacco, pepper, celery) were infected by tuf‐b. The gene vmp1 showed higher polymorphism in grapevines (nine profiles) than herbaceous plants (six) by RFLP analysis, in agreement with nucleotide sequences’ analysis and virtual digestions. Conclusions: The phylogenetic analysis of vmp1 gene sequences supports the RFLP data and demonstrates the accuracy of RFLP for preliminary assessments of genetic diversity of stolbur phytoplasmas and for screening different vmp types. Significance and Impact of the Study: Stolbur represents a serious phytosanitary problem in the areas under investigation, owing to heavy economic losses in infected grapevines and vegetables. Molecular information about the complex genotyping of the vmp1 gene provides useful data towards a better understanding of stolbur epidemiology. Moreover, this study clarifies some different vmp1 genotype classifications of stolbur, providing molecular data in comparison with previous investigations.     

Reaction of dopamine with D-glyceraldehyde under biomimetic conditions: stereoselective formation of tetrahydroisoquinolines and rate-accelerating effects of transition metal ions

In 0.05 M phosphate buffer, pH 7.4, and at 37 degrees C, dopamine underwent a smooth Pictet-Spengler condensation with D-glyceraldehyde and D,L-glyceraldehyde-3-phosphate to afford diastereoisomeric tetrahydroisoquinolines. In the case of D-glyceraldehyde 1a/1b were formed in ca. 2:1 ratio. Treatment with carbonyldiimidazole converted 1a and 1b into the corresponding oxazinoisoquinolinones 2a and 2b which were separated and stereochemically characterised by NMR analysis. Transition metal ions commonly occurring in biological systems (e.g. Cu2+ and Fe3+) markedly accelerated the formation of 1a-1b without affecting the product ratio. Mechanistic evidence suggested the reversible generation of Schiff base intermediates, detected by 1H NMR, which undergo stereoselective cyclisation according to the Felkin-Anh model. Metal-chelation at the catechol group facilitates the rate-determining nucleophilic attack to the imine moiety by enhancing the electron density at the site of cyclisation. These results highlight an apparently overlooked effect of transition metal ions on the Pictet-Spengler reaction under biomimetic conditions and provide a chemical basis to postulate a role of carbohydrate metabolites as modulatory agents of dopaminergic neurotransmission via conversion to potentially bioactive tetrahydroisoquinoline derivatives.     

Activities of 2,4-dihydroxy-6-n-pentylbenzoic acid derivatives

Esters of 2-hydroxy-4-methoxy-6-n-pentylbenzoic acid (2-8) (methyl, ethyl, butyl, pentyl, isopropyl, sec-butyl and benzyl), olivetol (9), methyl, ethyl, butyl perlatolates (10-12), 2,4-dihydroxy-6-n-pentylbenzoic acid (15), and methyl and ethyl esters of (15) were prepared through structural modifications of perlatolic acid (1) with the aim to detect new antifungal and antibacterial substances and also to evaluate the toxicity by the brine shrimp lethality assay against Artemia salina. The antifungal assays were carried out against the fungus Cladosporium sphaerospermum through the bioautography method, and methyl 2,4-dihydroxy-6-n-pentylbenzoate (13) showed the highest antifungal activity (2.5 yg). Olivetol (9) and 2,4-dihydroxy-6-n-pentylbenzoic acid (15) are also potent inhibitors of the growth of the fungus (5.0 microg). Except for methyl (10), the ethyl (11) and butyl (12) perlatolates were less active than perlatolic acid (1). The activities presented by methyl (2) and ethyl (3) 2-hydroxy-4-methoxy-6-n-pentylbenzoates and methyl (13) and ethyl (14) 2,4-dihydroxy-6-n-pentylbenzo-ates suggest that compounds with a free hydroxy group in the aromatic ring (C-4) have a more pronounced effect against C. sphaerospermum. Antibacterial activities were tested by the disc diffusion method using pathogenic strains of S. aureus and E. coli. The compounds were weakly active with inhibition zones between 9-15 mm. The 2-hydroxy-4-methoxy-6-n-pentylbenzoic esters 2-8 and alkyl perlatolates 10-12 were selective against E. coli. Perlatolic acid (1) and methyl 2-hydroxy-4-methoxy-6-n-pentylbenzoate (2) were the most active with LD50 values of 24.1 microM and 27.2 microM, respectively. The other compounds were not toxic to Artemia salina larvae.     

Identification of a drimenol synthase and drimenol oxidase from Persicaria hydropiper,involved in the biosynthesis of insect deterrent drimanes

The sesquiterpenoid polygodial, which belongs to the drimane family, has been shown to be an antifeedant for a number of herbivorous insects. It is presumed to be synthesized from farnesyl diphosphate via drimenol, subsequent C‐12 hydroxylation and further oxidations at both C‐11 and C‐12 to form a dialdehyde. Here, we have identified a drimenol synthase (PhDS) and a cytochrome P450 drimenol oxidase (PhDOX1) from Persicaria hydropiper. Expression of PhDS in yeast and plants resulted in production of drimenol alone. Co‐expression of PhDS with PhDOX1 in yeast yielded drimendiol, the 12‐hydroxylation product of drimenol, as a major product, and cinnamolide. When PhDS and PhDOX1 were transiently expressed by agro‐infiltration in Nicotiana benthamiana leaves, drimenol was almost completely converted into cinnamolide and several additional drimenol derivatives were observed. In vitro assays showed that PhDOX1 only catalyses the conversion from drimenol to drimendiol, and not the further oxidation into an aldehyde. In yeast and heterologous plant hosts, the C‐12 position of drimendiol is therefore likely to be further oxidized by endogenous enzymes into an aldehyde and subsequently converted to cinnamolide, presumably by spontaneous hemiacetal formation with the C‐11 hydroxyl group followed by oxidation. Purified cinnamolide was confirmed by NMR and shown to be deterrent with an effective deterrent dose (ED₅₀) of about 200–400 μg g^?1 fresh weight against both whiteflies and aphids. The putative additional physiological and biochemical requirements for polygodial biosynthesis and stable storage in plant tissues are discussed.     

A DNA glycosylase from Pyrobaculum aerophilum with an 8-oxoguanine binding mode and a noncanonical helix-hairpin-helix structure

Studies of DNA base excision repair (BER) pathways in the hyperthermophilic crenarchaeon Pyrobaculum aerophilum identified an 8-oxoguanine-DNA glycosylase, Pa-AGOG (archaeal GO glycosylase), with distinct functional characteristics. Here, we describe its crystal structure and that of its complex with 8-oxoguanosine at 1.0 and 1.7 A resolution, respectively. Characteristic structural features are identified that confirm Pa-AGOG to be the founding member of a functional class within the helix-hairpin-helix (HhH) superfamily of DNA repair enzymes. Its hairpin structure differs substantially from that of other proteins containing an HhH motif, and we predict that it interacts with the DNA backbone in a distinct manner. Furthermore, the mode of 8-oxoguanine recognition, which involves several hydrogen-bonding and pi-stacking interactions, is unlike that observed in human OGG1, the prototypic 8-oxoguanine HhH-type DNA glycosylase. Despite these differences, the predicted kinked conformation of bound DNA and the catalytic mechanism are likely to resemble those of human OGG1.