Association between plasmid carrying an expanded-spectrum cephalosporin resistance and biofilm formation in Escherichia coli

The formation of biofilm is a universal bacterial survival strategy. Biofilms occur on inert and living support in the natural environment and in industrial installations. This microenvironment leads to the horizontal transfer of genetic material between bacteria by physical contact. In order to evaluate the relationship between biofilm-forming capabilities, surface characteristics and plasmid content we purified from Salmonella a plasmid conferring resistance to cephalosporin and transferred it by electroporation to E.coli DH10B originally unable to form biofilm in inert surface. We demonstrated the association between a plasmid conferring resistance to expanded-spectrum cephalosporin and biofilm formation. We also noted that this plasmid influences the cell surface properties and cell motility.     

UV-B effect on constituents of Azolla caroliniana

Changes in growth and ultrastructure of Azolla caroliniana in response to elevated UV-B radiation were investigated. Exposure of plants to UV-B radiation for 1, 8, 16, 24 and 48 h exhibited a significant decrease in biomass and relative growth rate. This decrease resulted in an increase in doubling time over the control. Also, Chl a and b contents were significantly decreased especially after 16 h. The reduction was accompanied by a decrease in 5-aminolaevulinic acid content (precursor of chlorophyll). On the other hand, contents of carotenoid and UV-absorbing phenolic compounds (flavonoids and anthocyanins) were increased.     

Physiological, morphological and metabolic changes in Tetrahymena pyriformis for the in vivo cytotoxicity assessment of metallic pollution: Impact on d-β-hydroxybutyrate dehydrogenase

The individual cytotoxicity of cadmium chloride, iron sulphate and chromium nitrate has been investigated by using the freshwater ciliate Tetrahymena pyriformis. The metabolic enzymes and antioxidant defense biomarkers were assessed. The results obtained reveal that their metal salts have perturbed the physiology and morphology of T. pyriformis. Also, the biomarkers assessed were sensitive to the presence of metal salts and this sensitivity was metal salt and dose dependant. To estimate the impact of their metal salts on mitochondria, we studied their effects in vivo and in vitro on the d-β-hydroxybutyrate dehydrogenase (BDH) (EC 1.1.1.30) inner mitochondrial membrane enzyme. The results showed a high inhibition of BDH in terms of activity, protein expression and kinetic parameters.     

Nobiletin protects against diabetes-induced testicular injury via hypophysis–gonadal axis upregulation and amelioration of oxidative stress

Background

Testicular injury is one of the most serious problems associated with diabetes mellitus. The present study aimed to compare the effects of two different doses of nobiletin and analyze its mechanisms of action against diabetes-induced testicular impairment in rats.

Methods and results

Streptozotocin injection was used to induce diabetes. Diabetic rats received nobiletin orally at 10 or 25 mg/kg daily for 30 days. Diabetic rats displayed significant elevations in glucose, glycosylated hemoglobin (HbA1c), Homeostatic Model of Insulin Resistance (HOMA-IR), and pro-inflammatory cytokines, while the serum levels of insulin, testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were significantly reduced. Histological changes to positivity for caspase-3 and decreased androgen receptors (AR) immunoexpression were observed in diabetic rats. Both doses of nobiletin improved hyperglycemia, reduced pro-inflammatory cytokines, and augmented insulin, testosterone, LH, and FSH levels. LH and FSH receptors and cytochrome P450 17 α-hydroxylase (CYP17A1) were markedly downregulated in terms of both gene and protein expression in testicular tissues of the diabetic group, effects that were markedly ameliorated with both doses of nobiletin. In addition, both doses significantly reduced lipid peroxidation and caspase-3 immunoexpression and improved the activity of the antioxidant enzymes and AR in testicular tissues of the diabetic group.

Conclusion

Both nobiletin doses showed protective effects against diabetes-induced testicular injury by reducing oxidative stress, hyperglycemia, inflammation, and caspase-3 and upregulating the hypophysis–gonadal axis and AR. The high dose of nobiletin was more effective than the lower one.

     

Copper (II) complexes with N,S donor pyrazole-based ligands as anticancer agents

BioMetals - A group of bidentate nitrogen and sulfur donor pyrazole derivative ligands abbreviated as Na[RNCS(Pz)], Na[RNCS(PzMe2)], Na[RNCS(PzMe3)], Na[RNCS(PzPhMe)], Na[RNCS(PzPh2)], where...     

Patterns and Determinants of Halophilic Archaea (Class Halobacteria) Diversity in Tunisian Endorheic Salt Lakes and Sebkhet Systems

We examined the diversity and community structure of members of the halophilic Archaea (class Halobacteria) in samples from central and southern Tunisian endorheic salt lakes and sebkhet (also known as sebkha) systems using targeted 16S rRNA gene diversity survey and quantitative PCR (qPCR) approaches. Twenty-three different samples from four distinct locations exhibiting a wide range of salinities (2% to 37%) and physical characteristics (water, salt crust, sediment, and biofilm) were examined. A total of 4,759 operational taxonomic units at the 0.03 (species-level) cutoff (OTU_0.03s) belonging to 45 currently recognized genera were identified, with 8 to 43 genera (average, 30) identified per sample. In spite of the large number of genera detected per sample, only a limited number (i.e., 2 to 16) usually constituted the majority (≥80%) of encountered sequences. Halobacteria diversity showed a strong negative correlation to salinity (Pearson correlation coefficient = −0.92), and community structure analysis identified salinity, rather than the location or physical characteristics of the sample, as the most important factor shaping the Halobacteria community structure. The relative abundance of genera capable of biosynthesis of the compatible solute(s) trehalose or 2-sulfotrehalose decreased with increasing salinities (Pearson correlation coefficient = −0.80). Indeed, qPCR analysis demonstrated that the Halobacteria otsB (trehalose-6-phosphatase)/16S rRNA gene ratio decreases with increasing salinities (Pearson correlation coefficient = −0.87). The results highlight patterns and determinants of Halobacteria diversity at a previously unexplored ecosystem and indicate that genera lacking trehalose biosynthetic capabilities are more adapted to growth in and colonization of hypersaline (>25% salt) ecosystems than trehalose producers.     

3d interaction homology: The structurally known rotamers of tyrosine derive from a surprisingly limited set of information‐rich hydropathic interaction environments described by maps

Sidechain rotamer libraries are obtained through exhaustive statistical analysis of existing crystallographic structures of proteins and have been applied in multiple aspects of structural biology, for example, crystallography of relatively low‐resolution structures, in homology model building and in biomolecular NMR. Little is known, however, about the driving forces that lead to the preference or suitability of one rotamer over another. Construction of 3D hydropathic interaction maps for nearly 30,000 tyrosines reveals the environment around each, in terms of hydrophobic (π–π stacking, etc.) and polar (hydrogen bonding, etc.) interactions. After partitioning the tyrosines into backbone‐dependent (?, ψ) bins, a map similarity metric based on the correlation coefficient was applied to each map‐map pair to build matrices suitable for clustering with k‐means. The first bin (?200° ≤ ? < –155°; ?205° ≤ ψ < –160°), representing 631 tyrosines, reduced to 14 unique hydropathic environments, with most diversity arising from favorable hydrophobic interactions with many different residue partner types. Polar interactions for tyrosine include surprisingly ubiquitous hydrogen bonding with the phenolic OH and a handful of unique environments surrounding the tyrosine backbone. The memberships of all but one of the 14 environments are dominated (>50%) by a single χ₁/χ₂ rotamer. The last environment has weak or no interactions with the tyrosine ring and its χ₁/χ₂ rotamer is indeterminate, which is consistent with it being composed of mostly surface residues. Each tyrosine residue attempts to fulfill its hydropathic valence and thus, structural water molecules are seen in a variety of roles throughout protein structure. Proteins 2015; 83:1118–1136. © 2015 Wiley Periodicals, Inc.     

Nuclear targeted silver nanospheres perturb the cancer cell cycle differently than those of nanogold

Plasmonic nanoparticle research has become increasingly active due to potential uses in biomedical applications. However, little is known about the intracellular effects these nanoparticles have on mammalian cells. The aim of this work is to investigate whether silver nanoparticles (AgNPs) conjugated with nuclear and cytoplasmic targeting peptides exhibit the same intracellular effects on cancer cells as peptide-conjugated gold nanoparticles (AuNPs). Nuclear and cytoplasmic targeting spherical AgNPs with a diameter of 35 nm were incubated in a cancer (HSC-3) and healthy (HaCat) cell line. By utilizing flow cytometry, confocal microscopy, and real-time dark field imaging, we were able to analyze how targeting AgNPs affect the cell cycle and cell division. These experiments demonstrated that nuclear-targeting AgNPs cause DNA double-strand breaks and a subsequent increase in the sub G1 (apoptotic) population in our cancer cell model at much lower concentrations than previously reported for nuclear targeting AuNPs. Unlike the M phase accumulation seen in cancer cells treated with AuNPs, an accumulation in the G2 phase of the cell cycle was observed in both cell models when treated with AgNPs. Additionally, real-time dark field imaging showed that cancer cells treated with nuclear targeting AgNPs did not undergo cell division and ultimately underwent programmed cell death. A possible explanation of the observed results is discussed in terms of the chemical properties of the nanoparticles.