I have a general question and hopefully someone know about what I am trying to say.
I was told, without specific details, that there are beads you can use on an agar plate that mimic the feeling of moving through bacteria and eating bacteria, BUT they are completely empty nutritionally. Does anyone know if such a thing exists. If is there another way to have a plate half seeded with live nutritious bacteria and one with nutritionally empty ones? I don’t want toxic bacteria, or ones that will repel the worms. I wont the worms to be able to be attracted to the “food” source and then eventually leave that lawn. I am studying the perception of nutrients by the worms.
Sephadex beads in solution provide the feeling of bumping into small objects, such as bacteria. The response to the presence of hydrated sephadex beads is abnormal in dopamine mutants (see Sawin et al 2000). However, the smallest beads that I have seen used are much larger than E. coli. For example, G-200 superfine sephadex beads are 20-50 um (dry diameter). And the worms do not eat the beads - they provide mechano-sensory stimulation but no nutritional stimulation. In my hands, worms are not attracted to beads reconstituted in M9 or water.
One of the students in my lab is using fluorescent beads to monitor if worms are eating. I presume they are nutritionally inert. She is using the parameters as defined by this recent paper by the Samuel lab (with help from Leon Avery):
Proc Natl Acad Sci U S A. 2009 Nov 24;106(47):20093-6. Epub 2009 Nov 10.
Two size-selective mechanisms specifically trap bacteria-sized food particles in C. elegans
cheers for the replies. They really help. I will use the fluorescent beads. My intention is to study the dwelling/roaming behavior and play with using an attractant to make worms go from the food to the beads and then study how long it takes for them to go back, and how this behavior is affected by certain treatments I want to study.