Ochrobactrum sp. MPV1 from a dump of roasted pyrites can be exploited as bacterial catalyst for the biogenesis of selenium and tellurium nanoparticles.

BACKGROUND: Bacteria have developed different mechanisms for the transformation of metalloid oxyanions to non-toxic chemical forms. A number of bacterial isolates so far obtained in axenic culture has shown the ability to bioreduce selenite and tellurite to the elemental state in different conditions along with the formation of nanoparticles-both inside and outside the cells-characterized by a variety of morphological features. This reductive process can be considered of major importance for two reasons: firstly, toxic and soluble (i.e. bioavailable) compounds such as selenite and tellurite are converted to a less toxic chemical forms (i.e. zero valent state); secondly, chalcogen nanoparticles have attracted great interest due to their photoelectric and semiconducting properties. In addition, their exploitation as antimicrobial agents is currently becoming an area of intensive research in medical sciences. RESULTS: In the present study, the bacterial strain Ochrobactrum sp. MPV1, isolated from a dump of roasted arsenopyrites as residues of a formerly sulfuric acid production near Scarlino (Tuscany, Italy) was analyzed for its capability of efficaciously bioreducing the chalcogen oxyanions selenite (SeO32-) and tellurite (TeO32-) to their respective elemental forms (Se0 and Te0) in aerobic conditions, with generation of Se- and Te-nanoparticles (Se- and TeNPs). The isolate could bioconvert 2 mM SeO32- and 0.5 mM TeO32- to the corresponding Se0 and Te0 in 48 and 120 h, respectively. The intracellular accumulation of nanomaterials was demonstrated through electron microscopy. Moreover, several analyses were performed to shed light on the mechanisms involved in SeO32- and TeO32- bioreduction to their elemental states. Results obtained suggested that these oxyanions are bioconverted through two different mechanisms in Ochrobactrum sp. MPV1. Glutathione (GSH) seemed to play a key role in SeO32- bioreduction, while TeO32- bioconversion could be ascribed to the catalytic activity of intracellular NADH-dependent oxidoreductases. The organic coating surrounding biogenic Se- and TeNPs was also characterized through Fourier-transform infrared spectroscopy. This analysis revealed interesting differences among the NPs produced by Ochrobactrum sp. MPV1 and suggested a possible different role of phospholipids and proteins in both biosynthesis and stabilization of such chalcogen-NPs. CONCLUSIONS: In conclusion, Ochrobactrum sp. MPV1 has demonstrated to be an ideal candidate for the bioconversion of toxic oxyanions such as selenite and tellurite to their respective elemental forms, producing intracellular Se- and TeNPs possibly exploitable in biomedical and industrial applications.

Pectins, Hemicelluloses and Celluloses Show Specific Dynamics in the Internal and External Surfaces of Grape Berry Skin During Ripening.

Grapevine berry skin is a complex structure that contributes to the final size and shape of the fruit and affects its quality traits. The organization of cell wall polysaccharides in situ and their modification during ripening are largely uncharacterized. The polymer structure of Corvina berry skin, its evolution during ripening and related modifying genes were determined by combing mid-infrared micro-spectroscopy and multivariate statistical analysis with transcript profiling and immunohistochemistry. Spectra were acquired in situ using a surface-sensitive technique on internal and external sides of the skin without previous sample pre-treatment, allowing comparison of the related cell wall polymer dynamics. The external surface featured cuticle-related bands; the internal surface showed more adsorbed water. Application of surface-specific normalization revealed the major molecular changes related to hemicelluloses and pectins in the internal surface and to cellulose and pectins in the external surface and that they occur between mid-ripening and full ripening in both sides of the skin. Transcript profiling of cell wall-modifying genes indicated a general suppression of cell wall metabolism during ripening. Genes related to pectin metabolism-a ß-galactosidase, a pectin(methyl)esterase and a pectate lyase-and a xyloglucan endotransglucosylase/hydrolase, involved in hemicellulose modification, showed enhanced expression. In agreement with Fourier transform infrared spectroscopy, patterns due to pectin methyl esterification provided new insights into the relationship between pectin modifications and the associated transcript profile during skin ripening. This study proposes an original description of polymer dynamics in grape berries during ripening, highlighting differences between the internal and external sides of the skin.

Overexpression of PhEXPA1 increases cell size, modifies cell wall polymer composition and affects the timing of axillary meristem development in Petunia hybrida.

• Expansins are cell wall proteins required for cell enlargement and cell wall loosening during many developmental processes. The involvement of the Petunia hybrida expansin A1 (PhEXPA1) gene in cell expansion, the control of organ size and cell wall polysaccharide composition was investigated by overexpressing PhEXPA1 in petunia plants. • PhEXPA1 promoter activity was evaluated using a promoter-GUS assay and the protein's subcellular localization was established by expressing a PhEXPA1-GFP fusion protein. PhEXPA1 was overexpressed in transgenic plants using the cauliflower mosaic virus (CaMV) 35S promoter. Fourier transform infrared (FTIR) and chemical analysis were used for the quantitative analysis of cell wall polymers. • The GUS and GFP assays demonstrated that PhEXPA1 is present in the cell walls of expanding tissues. The constitutive overexpression of PhEXPA1 significantly affected expansin activity and organ size, leading to changes in the architecture of petunia plants by initiating premature axillary meristem outgrowth. Moreover, a significant change in cell wall polymer composition in the petal limbs of transgenic plants was observed. • These results support a role for expansins in the determination of organ shape, in lateral branching, and in the variation of cell wall polymer composition, probably reflecting a complex role in cell wall metabolism.

A remark on a dynamical stochastic model in G. V. Schiaparelli's evolution theory.

It is well known that Giovanni Virginio Schiaparelli (1834-1910) wrote in 1898 an essay, Forme organiche naturali e forme geometriche pure. Studio comparativo, which was also appreciated by Vito Volterra (1860-1940). Recent studies have revised Schiaparelli's evolutionary ideas with new proposals and from this it is possible to obtain a dynamical (deterministic) model. In this paper I propose a related stochastic model (as toy model): thanks to this tool, we can describe a speciation phenomenology.

Active rearrangements in the cell wall follow polymer concentration during postharvest withering in the berry skin of Vitis vinifera cv. Corvina.

During grape postharvest withering, a worldwide practice used to produce important high-quality wines, the solute concentration increases due to dehydration, and many organoleptic and quality traits, especially related to the berry skin, are affected in a cultivar-specific manner. Nevertheless, a complete comprehension of the underlying processes is still lacking. In this work, we applied ATR-FTIR micro-spectroscopy combined with PCA to monitor cell wall biochemical changes at three stages during postharvest withering on the internal and external sides of the berry skin of the Vitis vinifera cv. Corvina, an important local variety of the Verona province in Italy. The obtained results were integrated by profiling xylogucans and pectins through immunohistochemistry and by genome-wide transcriptomic analysis performed at the same withering stages. Our analysis indicates a gradual passive polymer concentration due to water loss in the first two months of postharvest withering, followed by active structural modifications in the last month of the process. Such rearrangements involve xyloglucans in the internal surface, cuticle components and cellulose in the external surface, and pectins in both surfaces. Moreover, by investigating the expression trend of cell wall metabolism-related genes, we identified several putative molecular markers associated to the polymer dynamics. The present study represents an important step towards an exhaustive comprehension of the postharvest withering process, which is of great interest from both the biological and technological points of view.

Selenite biotransformation and detoxification by Stenotrophomonas maltophilia SeITE02: Novel clues on the route to bacterial biogenesis of selenium nanoparticles.

A putative biosynthetic mechanism for selenium nanoparticles (SeNPs) and efficient reduction of selenite (SeO32-) in the bacterial strain Stenotrophomonas maltophilia SeITE02 are addressed here on the basis of information gained by a combined approach relying on a set of physiological, chemical/biochemical, microscopy, and proteomic analyses. S. maltophilia SeITE02 is demonstrated to efficiently transform selenite into elemental selenium (Se°) by reducing 100% of 0.5mM of this toxic oxyanion to Se° nanoparticles within 48h growth, in liquid medium. Since the selenite reducing activity was detected in the cytoplasmic protein fraction, while biogenic SeNPs showed mainly extracellular localization, a releasing mechanism of SeNPs from the intracellular environment is hypothesized. SeNPs appeared spherical in shape and with size ranging from 160nm to 250nm, depending on the age of the cultures. Proteomic analysis carried out on the cytoplasmic fraction identified an alcohol dehydrogenase homolog, conceivably correlated with the biogenesis of SeNPs. Finally, by Fourier Transformed Infrared Spectrometry, protein and lipid residues were detected on the surface of biogenic SeNPs. Eventually, this strain might be efficaciously exploited for the remediation of selenite-contaminated environmental matrices due to its high SeO32- reducing efficiency. Biogenic SeNPs may also be considered for technological applications in different fields.

A hand-made supplementary food for malnourished children.

We tested the possibility to prepare a hyperproteic and hyperenergetic supplementary food for malnutrition rehabilitation in children starting from available ingredients in popular markets in Sierra Leone. Twelve residents in Paediatrics from University of Parma, Italy, prepared in a hospital near the capital Freetown with modest technology a mixture of peanut flour, palm oil, milk powder, sugar and vitamins to which they gave the name of "Parma pap". Three hundred and thirty-two malnourished children (mean age 14±6.3 months) who were receiving Feeding Program Supplementations (FPS), were enrolled in the study: 177 participants received randomly FSP portions only (Group 1), and 159 participants were treated with FSP regimen plus a supplement of "Parma pap" (Group 2). Outcomes of the study were computed as WHZ-score increment (Δ value) by subtracting the discharge WHZ-score from the admission WHZ-score. The best Δ-WHZ-scores (>+4) were recorded among participants of Group 2 (64%) rather than in Group 1 (21%; p=0.040). The children receiving FSP portions plus "Parma pap" recovered faster (5.54 week on average) than those treated with FSP regimen only (8.16 on average). The percentage of children who did not recover was higher in Group 1 (25.3%) than in Group 2 (; 13%; p=0.05). A slight positive correlation has been found between WHZ-scores at admission and at the end of the study (r=0.19; p=0.045). During the experience in Sierra Leone we have had the chance to give "Parma pap" to twenty one malnourished children admitted to Xaverian Mission in Makeni, northern Sierra Leone, not taking other supplementary food. Sixteen of these children recovered in 4.9 week on average and five in 6 to 8 weeks. Mean Δ-WHZ-scores ranged between + 1 and + 5. The data from the present study suggest that "Parma pap" could be an effective additional food to FPS regimen in malnutrition recovering. Further researches are needed on the contrary to prove if "Parma pap" could be defined as a veritable ready to use therapeutic food, although this characteristic seems already to result from the experience in Makeni Mission.

Use of ATR-FTIR microspectroscopy to monitor autolysis of Saccharomyces cerevisiae cells in a base wine.

In this study, we evaluated the potentialities of ATR-FTIR microspectroscopy coupled to PCA in monitoring the major biochemical changes that occur during the autolysis of yeasts used for sparkling wine production. For this purpose, mid-infrared measurements were made on cells of the model strain Saccharomyces cerevisiae EC1118 in the course of autolysis induced at 30 degrees C for five days in a model and in a base wine. By relating principal component loadings to the corresponding absorption bands, it was shown that they well describe compositional modifications induced by autolytic process on yeast cells, such as partial hydrolysis of proteins, increase of peptides, free nucleotides, lipids, mannans, and beta-1,3 glucans. The corresponding score-score plots allowed us to monitor the different kinetics and to distinguish among faster, intermediate, and slower processes. ATR-FTIR microspectroscopy coupled with PCA is proposed as a sensitive method that can provide useful information to select efficient yeast strains, capable of accelerated autolysis, to be used in the second fermentation and aging of sparkling wines.