counting worms

Model Organism: Worms Scientific Discussion
1

Hi,
first of all I would like to say sorry for my English :wink: could anyone tell me if there are any procedures how to count worms? I don’t have good equipment for that and maybe there is some roughly methods? I’ll be very grateful for answering.
Marta

2

there are a number of methods, it really dependents upon the purpose. For example, we routinely count worms during chemotaxis assays by photographing the plate at low power (so that a circle of 1cm is in the viewfinder) and then using the manual count function in the software ImageJ (which is open source).

For repeated counts (many plates) or where there are many worms, there are a number of automated counters (hardware and software) available that make things a little easier. Perhaps other members will tell you about their favourite?

If you just want to know roughly how many worms are on a plate then you can divide the plate into a grid and count a representative number of ‘squares’ to calculate an average. This assumes of course that the worms are evenly distributed which often they are not and also tells you nothing about the relative numbers of worms of different ages.

A simple dissecting microscope, camera and ImageJ is a good start.

Steve

3

I agree, it depends on the purpose. If you are searching for brood size or survival rates, and do not need to keep the worms after counting them, one typically picks the worms off as you count and burns them. I would pick 10-20, burn them, and then add those numbers to a counter (as Steve suggested) or a piece of paper. A faster way would be to use a vacuum aspirator with a small pipet tip (a P10 tip or a gel loading tip), and you suck the worms off as you count.

(a different) Steve

:slight_smile:

4

Thanks to all of U, but I’m still thinking about something else. Using article: Chemotaxis by the Nematode Caenorhabditis elegans: Identification of Attractants and Analysis of the Response by Use of Mutants, Samuel Ward* I’m trying to show (more or less) the influence of attractants on worms. That’s why:

  1. I’m taking plate with worms & wash it with M9 buffer, then centrifuge and wash again ( it really doesn’t matter)
    The most important thing for me is (when I remove supernatant and at the bottom of corning I have pellet withmany, many worms)…
    to estimate or even to know how many ul or something I have to take to have for example 2 or 3 single worms. Like in that article.
    Is it now clear?
    I would be really glad:) Thank U all!!!
5

Ah OK. Then you can resuspend your worm pellet in a known volume, say 500µL but it could be more if you have a lot of worms.

Then spot 5 x 10µL aliquots onto a petridish lid and count the number of worms in each aliquot using a dissecting microscope.

Calculate the number in the whole sample, spin the worms down and resuspend at the concentration you want.

Steve