Role of Zinc Oxide Nanoparticles in Countering Negative Effects Generated by Cadmium in Lycopersicon esculentum

Journal of Plant Growth Regulation - Nanotechnology now plays a revolutionary role in many applications; nanomaterials have experienced significant importance in both basic and applied sciences as...     

Diarrheal and Environmental Isolates of Aeromonas spp. Produce a Toxin Similar to Shiga-Like Toxin 1

Diarrheal and environmental isolates of 39 strains of Aeromonas spp. were studied for detection of virulence factors. Although these 39 strains did not produce either heat-labile or heat-stable enterotoxins, culture filtrates of 31 strains produced cytopathic effects on Vero cells. Among these, culture filtrates of three strains of Aeromonas hydrophila and one strain of Aeromonas caviae could be neutralized by Escherichia coli O157:H7 Shiga-like toxin 1 antiserum. A single band of plasmid DNA of 2.14 kbp was isolated from these strains of Aeromonas spp. and E. coli O157:H7, which could be amplified by the polymerase chain reaction (PCR), employing oligonucleotide primers from the Shiga-like toxin 1 (SLT1) gene of E. coli O157:H7. E. coli HB 101 cells when transformed with the same plasmid showed cytopathic effects on Vero cells, which indicates that the SLT 1 homolog gene(s) of Aeromonas spp. is plasmid encoded. These results suggest that Aeromonas spp. may also produce Shiga-like toxin 1, or at least a cytotoxin with some homology with the Shiga-like toxin 1 of E. coli O157:H7.     

Photocleavable peptide-oligonucleotide conjugates for protein kinase assays by MALDI-TOF MS

Robust methods for highly parallel, quantitative analysis of cellular protein tyrosine kinase activities may provide tools critically needed to decipher oncogenic signaling, discover new targeted drugs, diagnose cancer and monitor patients. Here, we describe proof-of-principle for a novel protein kinase assay with the potential to help overcome these challenges. MALDI-TOF mass spectrometry provides an ideal tool for label-free multiplexed analysis of peptide phosphorylation, but is poorly matched to homogeneous assays and complex samples. Thus, we conjugated a common oligonucleotide tag to multiple peptide substrates, offering efficient capture from solution-phase kinase reactions by annealing to the complementary sequence tethered to PEG-passivated superparamagnetic microparticles. To enable reversible conjugation, we developed a novel bifunctional cross-linker allowing simple and efficient preparation of photocleavable peptide-oligonucleotide conjugates. After washing away contaminants and following photorelease, MALDI-TOF analysis yielded relative phosphorylation of each peptide with high sensitivity and specificity. Validating the hybridization-mediated multiplexed kinase assay, when three peptide substrate-oligonucleotide conjugates were mixed with the tyrosine kinase c-Abl and ATP, we readily observed their differential phosphorylation yet measured a common IC(50) for the Abl kinase inhibitor imatinib. This new assay enables analysis of protein kinase activities in a multiplexed format amenable to screening inhibitors against multiple kinases in parallel, an important capability for drug discovery and predictive diagnostics.