PslD is a secreted protein required for biofilm formation by Pseudomonas aeruginosa

The function of pslD, which is part of the psl operon from Pseudomonas aeruginosa, was investigated in this study. The psl operon is involved in exopolysaccharide biosynthesis and biofilm formation. An isogenic marker-free pslD deletion mutant of P. aeruginosa PAO1 which was deficient in the formation of differentiated biofilms was generated. Expression of only the pslD gene coding region restored the wild-type phenotype. A C-terminal, hexahistidine tag fusion enabled the identification of PslD. LacZ and PhoA translational fusions with PslD indicated that PslD is a secreted protein required for biofilm formation, presumably via its role in exopolysaccharide export.     

PslD Is a Secreted Protein Required for Biofilm Formation by Pseudomonas aeruginosa

The function of pslD, which is part of the psl operon from Pseudomonas aeruginosa, was investigated in this study. The psl operon is involved in exopolysaccharide biosynthesis and biofilm formation. An isogenic marker-free pslD deletion mutant of P. aeruginosa PAO1 which was deficient in the formation of differentiated biofilms was generated. Expression of only the pslD gene coding region restored the wild-type phenotype. A C-terminal, hexahistidine tag fusion enabled the identification of PslD. LacZ and PhoA translational fusions with PslD indicated that PslD is a secreted protein required for biofilm formation, presumably via its role in exopolysaccharide export.     

Food availability and reproduction affects lipid and fatty acid composition of the brown mussel, Perna perna, raised in suspension culture

We examined the influence of the reproductive cycle and environmental factors on variations of the condition index (CI), tissue dry mass, shell size, total lipid content, and relative percent of fatty acids in the mussel, Perna perna. Spat or juveniles were reared to commercial size (70 mm) in suspension culture in the Golfo de Cariaco, Venezuela between May and October 2004. The dry mass of soft tissues and shell, a visual assessment of gonadal status and the organism lipid profile were established every fortnight. In parallel, we measured the environmental conditions, following chlorophyll a, salinity, temperature and seston levels. After an initial decrease, the CI rose and remained high until August after which it decreased continuously until October. Total lipid values also decreased initially, after which they showed two periods of rapid recuperation and depletion, the first between May and August and the second between August and October. Similar tendencies were noted in the fatty acids, C18:3n-3, C18:4n-3 and C22:6n-3. Correlation analysis found no significant relationships between environmental parameters and the variations in total lipids. However, significant correlations were noted between fatty acids and specific environmental parameters. In particular, temperature was inversely correlated with C14:0, C16:1n-7, C18:0, C18:1n-9 and 20:5n-3. Chlorophyll a was positively correlated with C14:0, C16:1n-7, C18:1n-7, C18:4n-3 and 20:4n-6. On the other hand, gametogenesis had an effect on C14:0, C16:1n-7, C18:1n-9 and C18:1n-7, while spawned and gonadal regression states had an effect on fatty acid 20:4n-6. Temperature and chlorophyll a levels strongly influenced the proportion of mussels spawning, suggesting that their influence upon lipid composition may be secondary to their impact upon reproduction. Despite the thermal stability of this tropical system, the lipid composition of mussels changed markedly during the study, reflecting the central role of diet and reproductive investment upon lipid composition.     

Studies on the antimutagenesis of Phyllanthus orbicularis: mechanisms involved against aromatic amines

Phyllanthus orbicularis is a medicinal plant, endemic to Cuba, whose aqueous extract has proven antiviral properties. This plant extract is being studied for treatment of viral diseases in animals and humans. Antimutagenic activities of this plant aqueous extract have been investigated as an additional and possible valuable property. Antimutagenesis was assayed against the mutagenic activity of m-phenylenediamine (m-PDA), 2-aminofluorene (2-AF), 1-aminopyrene (1-AP), 2-aminoanthracene (2-AA) and 9-aminophenantrene (9-AP) in Salmonella typhimurium (S. typhimurium) YG1024, in different co-treatment approaches. This plant extract produced a significant decrease of the mutagenesis mediated by these aromatic amines (AA) in the following order: m-PDA>2-AA>2-AF>9-AP>1-AP. Interactions with S9 enzymes and transformation of promutagenic amines and their mutagenic metabolites by chemical reactions to non-mutagenic compounds are proposed as possible mechanisms of antimutagenesis. Mutagenesis mediated by m-PDA was almost completely abolished when S9 mixture was co-incubated with the plant extract during 40 min, previous to the addition of the m-PDA and bacterial cells to the assay. Similar results were found with 2-AA and 1-AP, but the reduction of the mutation rate was not so dramatic. In contrast, the most significant antimutagenic effect against 2-AF and 9-AP was seen when these chemicals were co-incubated with the plant extract, before addition of the S9 mixture and bacterial cells to the assay. Therefore, inhibition or competition for S9 enzymes seems to be the main antimutagenic mechanism of this plant extract against m-PDA, 2-AA and 1-AP, whilst a chemical modification of 2-AF and 9-AP into non-promutagenic derivatives is likely to be the main mechanism of antimutagenesis against both compounds.     

Identification of the Adapter Molecule MTSS1 as a Potential Oncogene-Specific Tumor Suppressor in Acute Myeloid Leukemia

The adapter protein metastasis suppressor 1 (MTSS1) is implicated as a tumor suppressor or tumor promoter, depending on the type of solid cancer. Here, we identified Mtss1 expression to be increased in AML subsets with favorable outcome, while suppressed in high risk AML patients. High expression of MTSS1 predicted better clinical outcome of patients with normal-karyotype AML. Mechanistically, MTSS1 expression was negatively regulated by FLT3-ITD signaling but enhanced by the AML1-ETO fusion protein. DNMT3B, a negative regulator of MTSS1, showed strong binding to the MTSS1 promoter in PML-RARA positive but not AML1-ETO positive cells, suggesting that AML1-ETO leads to derepression of MTSS1. Pharmacological treatment of AML cell lines carrying the FLT3-ITD mutation with the specific FLT3 inhibitor PKC-412 caused upregulation of MTSS1. Moreover, treatment of acute promyelocytic cells (APL) with all-trans retinoic acid (ATRA) increased MTSS1 mRNA levels. Taken together, our findings suggest that MTSS1 might have a context-dependent function and could act as a tumor suppressor, which is pharmacologically targetable in AML patients.     

Bioinspired Gold Nanoparticle Synthesis Using Terminalia bellerica Fruit Parts and Exploring Their Anti‐bacterial Potency In Vitro

Gold nanoparticles with their excellent biocompatibility are extensively used in pharma and biological applications. Terminalia bellerica (TB) dry fruit parts mediated gold nanoparticles were synthesized using the aqueous extracts. The secondary metabolites screening of the aqueous extracts was done using phytochemical analysis. The green synthesized gold nanoparticles show vibrant colours. They were characterized using UV–Visible spectroscopy, FT-IR spectroscopy, XRD analysis and FE-SEM. The analytical characterization methods ensured the formation of nanoparticles and could predict the nanometric size of the nanoparticles. The study also lay to determine the antibacterial potential of the TB fruit parts and TB fruit parts mediated gold nanoparticles. The pathogens chosen for the study were pathogens from clinical species such as Acinetobacter pneumonia, Bacillus subtilis, and Enterococcus faecalis which cause common infections. The TB fruit part extracts, as well as TB fruit parts mediated gold nanoparticles were capable enough to destroy clinical pathogens.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12088-021-00937-3.     

Antimutagenic mechanisms of Phyllanthus orbicularis when hydrogen peroxide is tested using Salmonella assay

Phyllanthus orbicularis is a medicinal plant, endemic to Cuba, whose aqueous extract has proven antiviral properties and antimutagenic activities against aromatic amines and hydrogen peroxide. In addition, this plant extract presents antioxidant activity. In this paper, using the Salmonella assay with the experimental approaches of co-incubation, pre- and post-treatments, it is shown that the P. orbicularis extract protects bacterial cells from oxidative damage and mutation by some intracellular mechanism, irrespective of its antioxidant activity.