Science Buddies: "Ask an Expert"

Hello,

I'm currently working on a project involving C. elegans. More specifically, I want to test how artifical food coloring affects the repulisive time of the organism. In order to do this, I think it would be important to obtain an age-synchronized population of the worm. I've researched two methods of doing this:

1) Combine bleach, sodium hydroxide, and water and shake for about 5 minutes. This is the most popular method, but I'm not sure if my fair would allow me to do it because sodium hydroxide has a pH of 14. Furthermore, this would result in a highly exothermic reaction that I'm not sure how to handle. (I know that NaOH can produce toxic gases when heated, so would this reaction have the potential of unleashing them?)

2) Individually "pick" adult worms of the growth plate. My number one worry here is that I don't have experience with doing this, so I fear I would damage the worms and introduce more error into my experiement than I'm eliminating. This also sounds really time consuming, and I don't want to spend a lot of time on this step of the project.

Do you have any suggestions on how I can safely maintain an age-synchronized population of C. elegans? Experimentation starts on November 4th, but I need to have my procedure and risks assements turned in before then. Thank you!

Hi,

Thanks for your questions -- I saw that you needed to start by 11/4, so I hope it is not too late and we can still help!

Both of these methods are pretty standard for obtaining a synchronous culture of C. elegans of the same age. In my experiences working with C. elegans, I have always used the bleaching method. As you mentioned, it is quicker and easier and the bleach kills off the adult worms so that only the eggs remain. The reaction is exothermic, but not so much that you can't touch the tube with gloves on. The bleach/NaOH solution should be prepared and added to the worm culture under a flow hood for your protection and in case there are any toxic gases being released (although you should cap the tube anyway to prevent this).

Please see the protocol here that I have used: https://pmc.ncbi.nlm.nih.gov/articles/PMC3197298/

Best of luck on your project!
-Brandi

Thank you for your reply!

I'm interested in chunking the C. elegan nematodes at the beginning of my experiment to plain NGM plates (that is, the plate won't contain any bateria). I've heard that when chunking worms, the nematodes will move from the "chunked" agar to a food source. Hence, I'm wondering: will the worms still move from an agar square if the dish they're being introduced to doesn't have any bacteria?

Hi, I apologize I missed your reply. If you want to chunk the C. elegans, you will transfer "chunks" of agar (with worms) from one NGM plate to a fresh NGM plate seeded with bacteria for food. I have previously used E. coli OP50 as a food source for the worms. If you chunk your C. elegans onto a plate without food, they might migrate from the agar chunk, but you would be starving the worms and this would affect their growth and they would likely enter the "dauer" phase. Please see this chapter here which details the chunking method in section 4: https://www.ncbi.nlm.nih.gov/books/NBK1 ... ew%20plate.

Hope it helps!
-Brandi