Anti-Serotonin protocol with detailed notes
Solutions for Anti-Serotonin staining
Last modified: 8 July 2014
1) Wash worms off plate with M9, put into 1.5 ml microcentrifuge tubes, spin down 30 sec in mini-centrifuge, remove supernatant.
- Note: One 60 mm plate with a dense, well-fed culture has plenty of worms for a staining experiment.
2) Rinse 2-3x with M9, spinning down and removing supernatant
- Note: One pasteur pipet-full is ~1.5 ml. Remove supernatant consistent with retaining as many worms as possible.
In this protocol, "Rinse" always means adding the maximum fluid that will fit in the tube, i.e., one pipet-full.
3) Fix overnight (ON) at 4 degrees C in 500 - 750 µl of 4% paraformaldehyde/PBS.
- Note: Paraformaldehyde is somewhat toxic and probably carcinogenic. Work with it in the hood with gloves and lab coat.
- Note: Over-fixation kills staining. Staining seems to work better with 12-16 hr fixation vs. 24 hr. Two days of fixation
- Note: 4% paraformaldehyde can be kept in the freezer for months. It can be thawed and used for about 2 weeks if kept at
4o C. If a precipitate has formed If in a hurry, thaw tube of 4% paraformaldehyde in hot water; be
sure to cool on ice before putting on worms. Hot fix kills all staining! (Also, if a precipitate has formed, vortex the solution
vigorously. Heating the solution again to 60-70 C may be necessary if substantial precipitate remains.)
4) Rinse 3x in 0.5% Triton X-100/PBS.
- Note: Put the paraformaldehyde into the waste container in the hood.
- Note: After this rinse, the fixed worms can be kept at 4o C for several days if necessary
before proceeding, perhaps up to weeks. For preps with marginal staining, however, it is probably better not to wait.
5) Incubate ON at 37o C in 500 µlof 5% beta-ME/1% TX-100/0.1 M Tris, pH 7.4. (Usually done rocking
on Nutator in small incubator. Use 'Sherlocks' to seal tops, or use tubes with other 'locking' feature.)
- Note: beta-ME (beta-mercaptoethanol aka 2-ME) is extremely smelly and somewhat toxic. Work with it in the hood with gloves
and lab coat. Container with the b-ME solution must be kept tightly closed or b-ME will evaporate. Make small batches in a glass container;
if staining stops working it could be from loss of potency of this solution from evaporation.
- Note: Overtreatment at this step (e.g., 2 days) will also abolish staining. Like with the fixation, it may be better to do closer to 12 hr
than 24 hr - i.e., set up in the evening, and rinse first thing the next morning.
6) Rinse 2x in 1% TX-100/0.1 M Tris, pH 7.4
- Note: Leave used pipets and tips in the hood for a day or two before discarding (the beta-ME will evaporate in that time).
7) Rinse 1x in collagenase buffer (1mM CaCl2/1% TX-100/0.1 M Tris, pH 7.4)
8) Incubate 30 min - 8 hr at 37o C in 2000 Units/ml Collagenase type IV (SIGMA C5138) in collagenase buffer.
(Usually done rocking on Nutator in small incubator. Use 'Sherlocks' to seal tops, or use tubes with other 'locking' feature.)
- Note: Usual volume is ~200 µl, but this is usually adjusted depending on mass of collagenase aliquot used. Most batches of
collagenase have ~500 U/mg, so typically you need ~4 mg/ml.
- Note: Digestion time is determined by examining 1-5 µl drops of worms (under the dissecting microscope) taken from the tube at
regular intervals, starting as early as 15-30 min. When gravid adult hermaphrodites begin to break open (usually at the vulva), stop treatment.
Once a time is determined for a batch of collagenase, one needn't necessarily monitor digestion. (Although it is safest to always monitor. You never
have exactly the same number & stages of worms or ultimate concentration of collagenase.) Digestion time should be re-checked when staining different
nematode species; this is sometimes also necessary for different C. elegans mutant strains. To get optimal head staining, one can do a more
'severe' digestion that fragments most worms. Heads will tend to stay intact, and give better staining, and may show more reliable faint cells.)
9) Rinse 3x in 0.5% Triton X-100/PBS
10) Incubate for 1 hr at RT in 100 µlof 1% BSA/0.5% Triton X-100/PBS
- Note: This step is intended to block non-specific Ab binding. It can be extended for hours to overnight; 1 hr is a minimal time.
- Note: BSA: Bovine serum albumen, Fraction V (Sigma A-9306), essentially immunoglobulin free for antibody solutions.
- Note: Boris Shtonda (Leon Avery's lab) recommends also including 10% goat serum (e.g., Sigma G9023) in the block and antibody steps. We have also done this
and it may reduce background staining; 1% GS may be enough to achieve the same effect.
11) Incubate ON at RT in 1:100 anti-serotonin in 1% BSA/0.5% Triton X-100/PBS.
- Note: Although this incubation is typically performed ON at RT, this step can also be shortened to 1-2 hr at 37o C.
- Note: A lot of our earlier experiments used a rabbit antiserum to serotonin (paraformaldehyde-conjugated to BSA; commercial antibodies are typically made to
glutaraldehyde-conjugated serotonin) from Henry Steinbusch (H.Steinbusch@np.unimaas.nl), Maastrict University, Netherlands. USDA importation permit
is no longer required for shipments, but appropriate endorsements must accompany shipment (see USDA
Guidelines for Importation #1103). We have for many years now been using a Sigma antiserum (S5545, lot 091K4831). Unfortunately, this (excellent) lot is no
longer available for sale. Nevertheless, the Sigma S5545 is one of the few available made to a paraformaldehyde-conjugated serotonin.)
- Note: Remove as much supernatant as possible (without losing worms) prior to adding the primary antibody. Add as little as 10 µl per tube
of 1:100 Ab solution; although it is not practical to make less than 50 µl of solution (i.e., 0.5 µl stock antiserum to 50 µl diluent).
- Note: Anti-serotonin is frozen at -70o C in 5 µl aliquots. Do not refreeze once thawed. It can safely
be stored for many weeks at 4o C. When finishing a tube, wash it out with the diluent to get as much Ab as possible.
12) Rinse 2x in 0.5% Triton X-100/PBS
13) Incubate for 1 hr in 0.1% BSA/0.5% Triton X-100/PBS
14) Incubate 2-4 hr at 37o C with 50 µl of 1:100 TRITC-conjugated goat anti-rabbit IgG in 1% BSA/0.5% Triton X-100/PBS.
- Note: This incubation can also be performed ON at 4o C.
- Note: Keep secondary antibody covered (e.g., with foil) at 4o C for weeks. Aliquots are frozen at
-70o C for long-term storage. Do not refreeze once thawed.
- Note: In our hands, TRITC-conjugated Abs fade much more slowly than those with FITC.
15) Rinse 3x in 0.5% Triton X-100/PBS
16) Rinse for 1 hr in 0.1% BSA/0.5% Triton X-100/PBS (You can typically skip this step and look right away, usually with a slightly higher background; if stopping
here, do add 0.1% BSA solution.)
17) Mount on agarose pad/coverslip and view with epiflourescence
- Note: After the collagenase step, worms are often very fragile. Slightly sliding the coverslip after mounting on agarose pad can completely destroy the
worms, leaving only shreds and pharynges.
- Note: Worms can typically be kept in tubes at 4o C in the dark after staining and viewed for several days or even weeks
later without significant fading.
- Note: We often add 1 µl of '100x' DAPI in water (10 µg/ml, so final conc is ~0.1 µg/ml) to the tube prior to mounting to see nuclei, and
to assess quality of permeabilization. Bad/uneven DAPI staining indicates insufficient permeabilization for good antibody staining (although good DAPI staining is
not a guarantee of sufficient permeabilization for antibody staining). Keep stock DAPI solution at 4o C or frozen and protected
In general, when rinsing, remove as much supernatant as possible without losing worms. Err on the side of removing less to retain worms. One exception is prior to
adding the primary antibody, when you want to remove as much supernatant as possible to have the highest effective concentration of Ab.
You can add Sodium Azide (NaN3, final concentration 0.1 - 0.05%) to most or all solutions to keep things from growing (then they
need not be autoclaved).
Solutions for Anti-serotonin protocol
1M Tris, pH 7.4
- Tris HCl 131.9 g/liter
- Tris Base 19.7 g/liter
(This solution should come out pretty close to pH 7.4, without further adjustment.)
10% Triton X-100 - This is much easier to work with than 100% Triton, which takes a long time to mix with water.
- Make up this stock by adding 10 ml Triton X-100 to 90 ml water.
- Put stir bar in bottle with water, then add Triton very slowly while stirring.
- Wash out pipet with solution at the end because much viscous Triton will be stuck to the inside of the pipet.
10X PBS (Phosphate Buffered Saline - Kenyon lab recipe)
|Final concentration ||MW||10x|| (for 1x) |
|150 mM NaCl||58.44||87.7 g|| (8.77 g) |
|8.4 mM Na2HPO4.7H2O||268.07|| 22.5 g|| (2.25 g) |
|1.8 mM NaH2PO4.H2O||137.99|| 2.5 g|| (0.25 g) |
4% paraformaldehyde in PBS
- dissolve in ~800 ml ddH2O
- adjust pH to 7.4 with approx. 13 ml 1N NaOH
(=13 mMoles/1liter 10x buffer or 1.3 mMoles//1liter 1x buffer)
- adjust to 1 liter
- aliquot and autoclave
Na2HPO4.7H2O = Sodium Phosphate, dibasic, heptahydrate (or if using Na2HPO4, use 11.94 g)
NaH2PO4.H2O = Sodium Phosphate, monobasic, monohydrate
- Heat ~80 ml dd water to 55-65o C in beaker stirring in hood (use dedicated beaker, stir bar and 'hood thermometer').
- Add 4 g paraformaldehyde powder or flakes, stir until dissolved. Add a few drops of 1M NaOH if necessary to help the paraformaldehyde to go into solution.
- Solution should become clear. Don't boil or heat longer than necessary.
- Add 10 ml 10x PBS and make up to 100 ml.
- Aliquot 10 ml each in 15 ml centrifuge tubes and store in -20o C freezer.
References for Anti-serotonin protocol
Neurotransmitter antisera were "invented" by H.W.M. Steinbusch et al. (1988). This protocol for C. elegans is derived from that originally published by Desai et al. (1988) with minor modifications (Loer & Kenyon, 1993). I have continued to modify the above protocol, and provide notes on variations that you can or cannot get away with.
Desai C, Garriga G, McIntire SL, Horvitz HR (1988) A genetic pathway for the development of the Caenorhabditis elegans HSN motor neurons. Nature 336:638-46.
Loer CM, Kenyon CJ (1993) Serotonin-deficient Mutants and Male Mating Behavior in the Nematode Caenorhabditis elegans. J Neurosci 13: 5407-5417.
Steinbusch HWM, Wouterlood FG, deVente J, Bol JGJM, Berkenbosch F (1988) Immunohistochemical localization of monoamines and cyclic nucleotides. Acta Histochem S35:85-106.
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