THE EFFECT OF HYDROGEN ION CONCENTRATION ON THE PRODUCTION OF CARBON DIOXIDE BY BACILLUS BUTYRICUS AND BACILLUS SUBTILIS

1. The maximum rate of CO₂ production of Bacillus butyricus was found to be at a pH value of 7; of Bacillus subtilis at pH 6.8. If the pH value be raised or lowered there is a progressive decrease in the rate of production of CO₂. 2. Spontaneous recovery follows the addition of alkali to either organism, while addition of acid is followed by recovery only upon addition of an equivalent amount of alkali, and is not complete except when the amount of acid is very small.     

Chromium binding Bacillus cereus VITSH1—a promising candidate for heavy metal clean up

Bacteria survive metal stress by several mechanisms and metal binding is one such mechanism which has been screened in the present study to investigate the survival strategies of metal resistant bacteria. The production of siderophores, a metal chelating agent, was detected by chrome azurol S agar assay. The changes in cell wall studied by analysing the peptidoglycan and teichoic acid content indicated an increase in the cell wall content. Evaluation of morphological and physiological alterations like cell size, granularity analysed by SEM and flow cytometry analysis revealed an increase in cell size and granularity respectively. The transformation of phosphates monitored by ³¹P NMR analysis indicated the presence of inorganic phosphate. Based on the cell wall changes and the ³¹P NMR analysis, the surface charge of the organism was studied by zeta potential which displayed a difference at pH7.     

COMPARATIVE STUDIES ON RESPIRATION : X. TOXIC AND ANTAGONISTIC EFFECTS OF MAGNESIUM IN RELATION TO THE RESPIRATION OF BACILLUS SUBTILIS.

1. Concentrations of MgCl₂ up to 0.01 M have little effect upon the rate or respiration of Bacillus subtilis; at 0.03 M there is an increase in the rate, while in the higher concentrations there is a gradual decrease. 2. There is a well marked antagonism between MgCl₂ and NaCl, and a very slight antagonism between MgCl₂ and CaCl₂.     

Conformational study of bovine lactoferricin in membrane-micking conditions by molecular dynamics simulation and circular dichroism

Lactoferricins are potent antimicrobial peptides released by pepsin cleavage of Lactoferrins. Bovine Lactoferricin (LfcinB) has higher activity than the intact bovine Lactoferrin, and is the most active among the other Lactoferricins of human, murine and caprine origin. In the intact protein the fragment corresponding to LfcinB is in an helical conformation, while in water LfcinB adopts an amphipathic β-hairpin structure. However, whether any of these structural motifs is the antibacterial active conformation, i.e., the one interacting with bacterial membrane components, remains to be seen. Here we present Circular Dichroism (CD) spectra and Molecular Dynamics (MD) simulations indicating that in membrane-mimicking solvents the LfcinB adopts an amphipathic β-hairpin structure similar to that observed in water, but differing in the dynamic behavior of the side-chains of the two tryptophan residues. In the membrane-mimicking solvent these side-chains show a high propensity to point towards the hydrophobic environment, rather than being in the hydrophobic core as seen in water, while the backbone preserves the hairpin conformation as found in water. These results suggest that the tryptophans might act as anchors pulling the stable, solvent-invariant hairpin structure into the membrane.     

Microculture Plaque Assay for Human and Simian Cytomegaloviruses

The plaque assay for human and simian cytomegaloviruses routinely carried out in 60-mm petri dishes (macrocultures) has been adapted for use in microcultures in flat-bottom 16-mm circular wells of disposable plastic trays. Virus titrations and serum neutralization assays carried out in microcultures yielded reproducible results that were identical to those obtained in macrocultures.     

Lack of ceramide generation and altered sphingolipid composition are associated with drug resistance in human ovarian carcinoma cells

PTX (Paclitaxel) is an antimitotic agent used in the treatment of a number of major solid tumours, particularly in breast and ovarian cancer. This study was undertaken to gain insight into the molecular alterations producing PTX resistance in ovarian cancer. PTX treatment is able to induce apoptosis in the human ovarian carcinoma cell line, CABA I. PTX-induced apoptosis in CABA I cells was accompanied by an increase in the cellular Cer (ceramide) levels and a decrease in the sphingomyelin levels, due to the activation of sphingomyelinases. The inhibition of acid sphingomyelinase decreased PTX-induced apoptosis. Under the same experimental conditions, PTX had no effect on Cer and sphingomyelin levels in the stable PTX-resistant ovarian carcinoma cell line, CABA-PTX.The acquisition of the PTX-resistant phenotype is accompanied by unique alterations in the complex sphingolipid pattern found on lipid extraction. In the drug-resistant cell line, the levels of sphingomyelin and neutral glycosphingolipids were unchanged compared with the drug-sensitive cell line. The ganglioside pattern in CABA I cells is more complex compared with that of CABA-PTX cells. Specifically, we found that the total ganglioside content in CABA-PTX cells was approximately half of that in CABA I cells, and GM3 ganglioside content was remarkably higher in the drug-resistant cell line. Taken together our findings indicate that: i) Cer generated by acid sphingomyelinase is involved in PTX-induced apoptosis in ovarian carcinoma cells, and PTX-resistant cells are characterized by their lack of increased Cer upon drug treatment, ii) PTX resistance might be correlated with an alteration in metabolic Cer patterns specifically affecting cellular ganglioside composition.     

Cartridge-based high-throughput purification of oligonucleotides for reliable oligonucleotide arrays

A novel, cartridge-based procedure for the efficient and irreversible detritylation of oligonucleotides is reported. This method, combined with a process for the elimination of depurinated fragments produces, in a highly parallel fashion, oligonucleotides with better purity than those traditionally obtained using reversed-phase high-performance liquid chromotography purification. Our combined detritylation and purification methodology compares favorably with commercial cartridge-based purification systems. The benefits of working with pure oligonucleotides, with regard to higher signal and better signal linearity, are shown in array-based hybridization experiments.     

Herbal melanin activates TLR4/NF-κB signaling pathway

Expression of many pro-inflammatory cytokines is controlled by the NF-κB signaling pathway. NF-κB is induced by LPS through activation of TLR4. Melanins extracted from fungal, plant and human sources modulate cytokine production and activate NF-κB pathway. We showed that a herbal melanin (HM) from Nigella sativa L. modulates cytokine production and suggested it as a ligand for TLR4. In this study we investigated the possibility that the HM-induced cytokine production is via an NF-κB signaling pathway. We found that HM induced the degradation of IκBα, a key step in the activation of NF-κB. Moreover, addition of IκB kinase (IKK) specific inhibitors effectively inhibited the observed HM-induced production of IL-8 and IL-6 by TLR4-transfected HEK293 cells and THP-1 cells. Our results have also shown that HM induced cleavage of caspase 8, and that this cleavage was partially abrogated by IKK inhibitors. We suggest that HM can modulate the inflammatory response by inducing IL-8 and IL-6 production via TLR4-dependent activation of the NF-κB signaling pathway.