Human Induced Pluripotent Stem Cell Derived Neuronal Cells Cultured on Chemically-Defined Hydrogels for Sensitive In Vitro Detection of Botulinum Neurotoxin.

Botulinum neurotoxin (BoNT) detection provides a useful model for validating cell-based neurotoxicity screening approaches, as sensitivity is dependent on functionally competent neurons and clear quantitative endpoints are available for correlating results to approved animal testing protocols. Here, human induced pluripotent stem cell (iPSC)-derived neuronal cells were cultured on chemically-defined poly(ethylene glycol) (PEG) hydrogels formed by "thiol-ene" photopolymerization and tested as a cell-based neurotoxicity assay by determining sensitivity to active BoNT/A1. BoNT/A1 sensitivity was comparable to the approved in vivo mouse bioassay for human iPSC-derived neurons and neural stem cells (iPSC-NSCs) cultured on PEG hydrogels or treated tissue culture polystyrene (TCP) surfaces.

Botulinum Neurotoxins Can Enter Cultured Neurons Independent of Synaptic Vesicle Recycling.

Botulinum neurotoxins (BoNTs) are the causative agent of the severe and long-lasting disease botulism. At least seven different serotypes of BoNTs (denoted A-G) have been described. All BoNTs enter human or animal neuronal cells via receptor mediated endocytosis and cleave cytosolic SNARE proteins, resulting in a block of synaptic vesicle exocytosis, leading to the flaccid paralysis characteristic of botulism.

Activity of botulinum neurotoxin type D (strain 1873) in human neurons.

Botulinum Neurotoxin type D (BoNT/D) causes periodic outbreaks of botulism in cattle and horses, but is rarely associated with human botulism. Previous studies have shown that humans responded poorly to peripheral injection of up to 10U of BoNT/D. Isolated human pyramidalis muscle preparations were resistant to BoNT/D, whereas isolated human intercostal muscle preparations responded to BoNT/D similarly as to other BoNT serotypes.

Analysis of gene expression in induced pluripotent stem cell-derived human neurons exposed to botulinum neurotoxin A subtype 1 and a type A atoxic derivative.

Botulinum neurotoxin type A1 (BoNT/A1) is a potent protein toxin responsible for the potentially fatal human illness botulism. Notwithstanding, the long-lasting flaccid muscle paralysis caused by BoNT/A has led to its utility as a powerful and versatile bio-pharmaceutical. The flaccid paralysis is due to specific cleavage of neuronal SNAREs by BoNTs.

Characterization of botulinum neurotoxin A subtypes 1 through 5 by investigation of activities in mice, in neuronal cell cultures, and in vitro.

Botulinum neurotoxins (BoNTs) are synthesized by Clostridium botulinum and exist as seven immunologically distinct serotypes designated A through G. For most serotypes, several subtypes have now been described based on nominal differences in the amino acid sequences. BoNT/A1 is the most well-characterized subtype of the BoNT/A serotype, and many of its properties, including its potency, its prevalence as a food poison, and its utility as a pharmaceutical, have been thoroughly studied.

Ralstonia solanacearum Dps contributes to oxidative stress tolerance and to colonization of and virulence on tomato plants.

Ralstonia solanacearum, an economically important soilborne plant pathogen, infects host roots to cause bacterial wilt disease. However, little is known about this pathogen's behavior in the rhizosphere and early in pathogenesis. In response to root exudates from tomato, R.

Moderate temperature fluctuations rapidly reduce the viability of Ralstonia solanacearum race 3, biovar 2, in infected geranium, tomato, and potato plants.

Most Ralstonia solanacearum strains are tropical plant pathogens, but race 3, biovar 2 (R3bv2), strains can cause bacterial wilt in temperate zones or tropical highlands where other strains cannot. R3bv2 is a quarantine pathogen in North America and Europe because of its potential to damage the potato industry in cooler climates. However, R3bv2 will not become established if it cannot survive temperate winters.