investigation-synaptic-taggingcapture-cross-capture-using-acute

Investigation of Synaptic Tagging/Capture and Cross-capture using Acute Hippocampal Slices from Rodents

Synaptic tagging and capture (STC) and cross-tagging are two important mechanisms at cellular level that explain how synapse-specificity and associativity ...

National University of Singapore

Calcaneal osteosarcoma.

Binary toxin of Lysinibacillus sphaericus is composed of two polypeptides; receptor binding BinB and toxic BinA. Both the polypeptides are required for maximal toxicity. It has been suggested that binary toxin exerts toxicity as a heterotetramer constituted by two copies of each of the component polypeptides. It has also been observed that oligomers consisting of two copies of BinA and BinB are pre-formed in L. sphaericus spore-crystals. However, recombinant proteins from Escherichia coli expression system elute individually as monomers. We purified the likely oligomeric complex from the spore-crystals of highly toxic L. sphaericus ISPC-8 strain and probed it with proteomic tools. The analysis showed that the high molecular mass complex in the toxic spore-crystals is composed of only surface layer protein (SlpC). The purified SlpC from the local isolate exists as a dimer and also showed poor mosquito-larvicidal activity.

An oligomeric complex of BinA/BinB is not formed in-situ in mosquito-larvicidal Lysinibacillus sphaericus ISPC-8.

Aeromonas hydrophila, a ubiquitous and virulent bacterial pathogen, affects a variety of fishes, including Labeo rohita. Existing treatment strategies comprise antibiotic therapies and attenuated bacterial strain-based vaccines. No functional subunit vaccine has been available until now. Given their key role in determining pathogenicity, outer membrane proteins have been successfully explored as potential vaccine candidates. We have devised a direct strategy for eliminating non-specific responses by selectively aiming the immune response against specific immunodominant epitopes of the outer membrane protein F (OmpF) of A. hydrophila (AhOmpF). Five putative epitopes of AhOmpF predicted in silico were genetically conjugated with heat labile enterotoxin chain B of E. coli (LTB). Recombinant fusion proteins expressed in E. coli were purified from solubilized inclusion bodies and refolded. The fusion protein retained GM1 ganglioside receptor binding activity of LTB, indicating proper folding. Four of the five fusion proteins were found to be highly immunogenic. Of the four proteins, antisera against the fusion protein (anti-rEpiF1) harboring 66-80 amino acid residues of the OmpF gave maximum cross-reactivity with the targeted rOmpF in enzyme-linked immunosorbent assay (ELISA) and was able to recognize both fusion partners-rOmpF and rLTB-in Western blot. Antibody isotyping of the antisera and cytokine array analysis of the culture supernatants of splenocytes from sensitized mice manifested a mixed Th1/Th2 immune response with a bias toward Th2. Anti-rEpiF1 antibodies were able to bind to the cell membrane of live A. hydrophila cells and agglutinate them. Our results thus suggest that the OmpF epitope (66-80) in fusion with a carrier protein is a promising vaccine candidate against A. hydrophila.

Identification and immunogenic potential of B cell epitopes of outer membrane protein OmpF of Aeromonas hydrophila in translational fusion with a carrier protein.

The crystallographic analysis of a marine cyanobacterium (Phormidium sp. A09DM) phycoerythrin (PE) that shows distinct sequence features compared with known PE structures from cyanobacteria and red algae is reported. Phormidium PE was crystallized using the sitting-drop vapour-diffusion method with ammonium sulfate as a precipitant. Diffraction data were collected on the protein crystallography beamline at the Indus-2 synchrotron. The crystals diffracted to about 2.1 Å resolution at 100 K. The crystals, with an apparent hexagonal morphology, belonged to space group P1, with unit-cell parameters a = 108.3, b = 108.4 Å, c = 116.6 Å, α = 78.94, β = 82.50, γ = 60.34°. The molecular-replacement solution confirmed the presence of 12 αβ monomers in the P1 cell. The Phormidium PE elutes as an (αβ)3 trimer of αβ monomers from a molecular-sieve column and exists as [(αβ)3]2 hexamers in the crystal lattice. Unlike red algal PE proteins, the hexamers of Phormidium PE do not form higher-order structures in the crystals. The existence of only one characteristic visual absorption band at 564 nm suggests the presence of phycoerythrobilin chromophores, and the absence of any other types of bilins, in the Phormidium PE assembly.

Mahima Sharma

Department of Physiology,
Yong Loo Lin School of Medicine,
Neurobiology/Aging Programme,
Life Sciences Institute,
Department of Physiology, Yong Loo Lin School of Medicine,
Neurobiology/Aging Programme, Life Sciences Institute

National University of Singapore

Investigation of Synaptic Tagging/Capture and Cross-capture using Acute Hippocampal Slices from Rodents