Scientist examining C. elegans in the NemaMetrix ScreenChip system under a microscope

Mike Harris working with the NemaMetrix ScreenChip system during a customer workshop.

At our inaugural ScreenChip Workshop, one of our very first customers, Dr. Mike Harris, had a burning question.

He’d been collaborating for years on a project that focused on the rabies virus surface glycoprotein (RGP), and through careful characterization, he had found a conserved peptide sequence in the RGP that bore homology to sequences found in snake toxins which inhibit nicotinic acetylcholine receptors (nAChRs).

But he needed to know: Does the RGP peptide also function to inhibit nAChRs within the central nervous system in an in vivo assay?

To answer his question, he turned to C. elegans and the ScreenChip System. During the workshop, we helped Mike to test his hypothesis both through microinjections of the peptide and through a peptide bath application protocol. Excitement rippled through the room as Mike, just a day after being introduced to our system, produced publishable data that showed a marked decrease in pharyngeal pumping following exposure to the RGP peptide. He’ll be presenting this data at this year’s Experimental Biology conference in San Diego, April 2-6.

Pharyngeal pumping is a physiological process that is dependent on nAChR signaling, and thus provides a powerful readout of perturbations to this biochemical pathway. Our system records the strong electrical signal from the pharynx quickly and with minimal effort. It provides you with meaningful, information dense data in minutes.

We were amazed and honored to be a part of Mike’s discovery. Be sure to check out his poster if you are at Experimental Bio this year, and check out his abstract below!

Presentation Time: Monday12:45 – 3:00 pm.
Program #: 969.2
Location: B296 969.2
Title: Screening Bioactivity of Virus Surface Glycoprotein Peptides using C. elegans Electropharyngeogram

The next ScreenChip WorkShop is on April 26th and we’d love for you to join us. As always, NemaMetrix will cover the cost of your food and lodging for the duration of the workshop. Email today to set up your experiments and reserve your spot. We can’t wait to see what new projects scientists will bring to life in our lab.

Abstract
The rabies virus surface glycoprotein contains an amino acid sequence similar to neurotoxin peptides known to bind to and inhibit the function of nicotinic acetylcholine receptors (nAChR). In preliminary experiments, we have shown that a peptide fraction of the neurotoxin-like-domain of the rabies virus inhibits signaling of central nervous system nAChRs. It has been shown, in the nematode Caenorhabditis elegans, that defined motor neuron MC acts as a neurogenic pacemaker for pharyngeal pumping and that nAChR are critical to excitation of the pharynx. We propose to use pharyngeal pumping in C. elegans as a screening assay for bioactivity of variants of virus glycoprotein peptides. In the present study we either administered a 29 amino acid peptide fraction (or a scrambled peptide) by microinjection through the cuticle proximal to the pharynx, or incubated animals for 90 minutes in concentrated peptide in M9 buffer solution (0 to 1.0 mM). Following treatments, we assessed pharyngeal pumping frequency during 2-minute observation periods using a non-invasive electropharyngeogram (NemaMetrix Katalyst 100). Pharyngeal pumping was absent in 6 of 7 animals receiving active peptide injection, while pharyngeal pumping in those receiving scrambled peptide was identical to untreated animals. Pharyngeal pumping was similarly absent or greatly attenuated in animals incubated in active peptide compared to controls. Results indicate that internal and external exposure to a peptide proposed to inhibit nAChR attenuate pharyngeal pumping in C. elegans in a manner expected by nAChR antagonism. Results support the bioactivity of this virus peptide fraction and the utility of C. elegans electropharyngeogram as a screen for bioactivity of variants of this peptide.