Intracellular recording in Snails – Juan Ferrada
Hi! I am Juan Ferrada, a biochemistry student at the lovely Universidad de Santiago in Chile. That’s me below with my girlfriend Rocia on campus. She is an important part of my project.
At the university I work with Dr. Patricio’s Rojas, a longtime colleague of Backyard Brains. Thanks to Patricio, Backyard Brains’ equipment has been to Antarctica!
In his lab, I study the temperature dependence of ion channels. I am in my last semester of studies, and in Chile every student has to do a “práctica” which is doing an internship for a clinical lab, company, or non-university research lab. Since Backyard Brains is in a sweet spot between company product development and neuroscience research, it makes doing a project with them an exciting, novel, and unorthodox práctica.
About my project
Backyard Brains started out studying neurons in cockroaches, then expanded to muscles in humans (EMG), than hearts (EKG), then brains (EEG), and then eyes (EOG). Now we return come back to the first love and dedication, the neuron, in search of the the most iconic symbol – the intracellularly recording action potential, Hodgkin-Huxley style. Teachers all the time ask Backyard Brains how to replicate, in a certain form, the famous Hodgkin Huxley intracellularly recorded action potential, and I am here to help! To begin, we will go to our backyard. Or, well, my girlfriend’s backyard (I told you Rocia would appear again).
Rocia has a garden, full of exotic and indigenous plants, from rosales to venus flytraps, but there are other things besides plants in the garden. There are things that eat my girlfriend’s plants:
Specifically, The scourge of my girlfriend is named Helix aspersa, also known as the pond snail. They like green leaves, but are especially of eating the tomato plant entirely, fruit and all. In France and Spain, these are the same snails that are cooked and served as elegant dishes (escargot).
These snails are interesting because they have very large pacemaker cells (which fire spontaneous action potentials like the ones you can see in your heart) located in the parietal ganglia (PG) involved in the chemo-mechanical sensation. Most classical intracellular recording techniques involve electrically stimulating the neuron, which can result in artifact, requires multiple electrodes, etc… Given that we will record from cells that are constantly firing spikes, we should be able to record spontaneous action potentials without the need for electrical stimulation. We want to make the preparation as simple as we can, BYB style.
Beginning the Project
To begin, we have to get the snails, which I collected during Easter Weekend. Check.
Now we will do some exploratory surgeries to extract the PG and try to isolate the neurons. To do this, we will anesthetize the snails with a Magnesium Chloride solution. Once we have the neurons, we will build a DIY glass electrode, mated with the original Neuron SpikerBox, to try to record the elusive intracellular action potential. Stay tuned as we begin this project. Saludos desde el Sur!
Chile has some a famous squid called Dosidicus gigas. With a mantle of 4.9 ft and 60 lbs it’s one of the largest of its kind. Experiments using the giant axon of this squid kickstarted the field of biophysics in Chile.
Due to Chile’s isolation, surrounded by the Andes Mountains, the Atacama desert, and the Pacific ocean, we have a very diverse unique fauna, indigenous to the country, and we have an even greater marine fauna thanks to the Humboldt current. But, we don’t have many mammals (around 150) for a country of such North-South extent. But… we do have the smallest wild cat in the americas, Leopardus guigna.
Tiwari SK, Woodruff ML.Helix aspersa neurons maintain vigorous electrical activity when co-cultured with intact H. aspersa ganglia. Comp Biochem Physiol C. 1992;101(1):163-74.