A desiccated dual-species subaerial biofilm reprograms its metabolism and affects water dynamics in limestone.

Understanding the impact of sessile communities on underlying materials is of paramount importance in stone conservation. Up until now, the critical role of subaerial biofilms (SABs) whether they are protective or deteriorative remains unclear, especially under desiccation. The interest in desiccated SABs is raised by the prediction of an increase in drought events in the next decades that will affect the Mediterranean regions' rich stone heritage as never before. Thus, the main goal of this research is to study the effects of desiccation on both the biofilms' eco-physiology and its impacts on the lithic substrate. To this end, we used a dual-species model system composed of a phototroph and a chemotroph to simulate biofilm behavior on stone heritage. We found that drought altered the phototroph-chemotroph balance and enriched the biofilm matrix with proteins and DNA. Desiccated SABs underwent a shift in metabolism to fermentation and a decrease in oxidative stress. Additionally, desiccated SABs changed the water-related dynamics (adsorption, evaporation, and wetting properties) in limestone. Water absorption experiments showed that desiccated SABs protected the stone from rapid water uptake, while a thermographic survey indicated a delay in water evaporation. Spilling-drop tests revealed a change in the wettability of the stone-SAB interface, which affected the water transport properties of the stone. Finally, desiccated SABs reduced stone swelling in the presence of water vapor. The biodeteriorative and bioprotective implications of desiccated SABs on the stone were ultimately assessed.

Basic HRCT patterns in diffuse interstitial lung disease.

The term interstitial lung disease (also called diffuse infiltrative lung disease) encompasses a heterogeneous group of processes characterized by the appearance of an inflammatory reaction in the alveolar wall that can be triggered by different antigens. This group of diseases represents a wide spectrum of processes of diverse etiologies, and sometimes the nomenclature can be confusing. High-resolution computed tomography (HRCT) is the imaging method of choice for the evaluation and diagnosis of interstitial lung diseases because it confirms the presence of lung disease and establishes the correct diagnosis for associated complications. Nevertheless, the definitive diagnosis of these entities requires the imaging findings to be interpreted together with their clinical manifestations and histological confirmation. In this group of diseases, HRCT findings play a fundamental role, being especially important for avoiding unnecessary biopsies. For these reasons, clinicians need to be familiar with the basic radiologic patterns associated with this group of lung diseases: septal, reticular, nodular, ground-glass, cystic, and consolidations. This chapter describes the features of these patterns and ways that they can present, and it reviews some of the most common interstitial lung diseases, emphasizing the predominant radiologic patterns in each of them.

Study of alkaloid berberine and its interaction with the human telomeric i-motif DNA structure.

The alkaloid berberine presents many biological activities related to its potential to bind DNA structures, such as duplex or G-quadruplex. Recently, it has been proposed that berberine may interact with i-motif structures formed from the folding of cytosine-rich sequences. In the present work, the interaction of this alkaloid with the i-motif formed by the human telomere cytosine-rich sequence, as well as with several positive and negative controls, has been studied. Molecular fluorescence and circular dichroism spectroscopies, as well as nuclear magnetic resonance spectrometry and competitive dialysis, have been used with this purpose. The results shown here reveal that the interaction of berberine with this i-motif is weak, mostly electrostatics in nature and takes place with bases not involved in C·C+ base pairs. Moreover, this ligand is not selective for i-motif structures, as binds equally to both, folded structure, and unfolded strand, without producing any stabilization of the i-motif. As a conclusion, the development of analytical methods based on the interaction of fluorescent ligands, such as berberine, with i-motif structures should consider the thermodynamic aspects related with the interaction, as well as the selectivity of the proposed ligands with different DNA structures, including unfolded strands.

3D-Structure of the interior fusion peptide of HGV/GBV-C by 1H NMR, CD and molecular dynamics studies.

In this work, we present a structural characterization of the putative fusion peptide E2(279-298) corresponding to the E2 envelope protein of the HGV/GBV-C virus by (1)H NMR, CD and MD studies performed in H(2)O/TFE and in lipid model membranes. The peptide is largely unstructured in water, whereas in H(2)O/TFE and in model membranes it adopts an helical structure (approximately 65-70%). The partitioning free energy DeltaG ranges from -6 to -7.5 kcal mol(-1). OCD measurements on peptide-containing hydrated and oriented lipid multilayers showed that the peptide adopts a predominantly surface orientation. The (1)H NMR data (observed NOEs, deuterium exchange rates, Halpha chemical shift index and vicinal coupling constants) and the molecular dynamics calculations support the conclusions that the peptide adopts a stable helix in the C-terminal 9-18 residues slightly inserted into the lipid bilayer and a major mobility in the amino terminus of the sequence (1-8 residues).

Phenyl sulfur mustard derivatives of distamycin A.

The design, synthesis, and cytotoxic activity of novel benzoyl and cinnamoyl sulfur mustard derivatives of distamycin A are described and structure activity relationships are discussed. These sulfur mustards are more potent cytotoxics than corresponding nitrogen mustards in spite of the lower alkylating power, while their sulfoxide analogues are substantially inactive. Cinnamoyl sulfur mustard derivative (7) proved to be one of the most active distamycin-derived cytotoxics, about 1000 times more potent than melphalan.

Thermal stability of Clostridium pasteurianum rubredoxin: deconvoluting the contributions of the metal site and the protein.

To provide a framework for understanding the hyperthermostability of some rubredoxins, a comprehensive analysis of the thermally induced denaturation of rubredoxin (Rd) from the mesophile, Clostridium pasteurianum was undertaken. Rds with three different metals in its M(SCys)4 site (M = Fe3+/2+, Zn2+, or Cd2+) were examined. Kinetics of metal ion release were monitored anaerobically at several fixed temperatures between 40 and 100 degrees C, and during progressive heating of the iron-containing protein. Both methods gave a thermal stability of metal binding in the order Fe2+ << Fe3+ < Zn2+ < Cd2+. The temperature at which half of the iron was released from the protein in temperature ramp experiments was 69 degrees C for Fe2+ Rd and 83 degrees C for Fe3+ Rd. Temperature-dependent changes in the protein structure were monitored by differential scanning calorimetry, tryptophan fluorescence, binding of a fluorescent hydrophobic probe, and 1H NMR. Major but reversible structural changes, consisting of swelling of the hydrophobic core and opening of a loop region, were found to occur at temperatures (50-70 degrees C) much lower than those required for loss of the metal ion. For the three divalent metal ions, the results suggest that the onset of the reversible, lower-temperature structural changes is dependent on the size of the MS4 site, whereas the final, irreversible loss of metal ion is dependent on the inherent M-SCys bond strength. In the case of Fe3+ Rd, stoichiometric Fe3+/cysteine-ligand redox chemistry also occurs during metal ion loss. The results indicate that thermally induced unfolding of the native Cp Rd must surmount a significant kinetic barrier caused by stabilizing interactions both within the protein and within the M(SCys)4 site.