Care of X. tropicalis while in our Laboratory
Frogs that are required for our experiments are brought out of the Trop colony and housed separately for egg and embryo collection. We house the frogs in plastic buckets for this. We use plastic containers designed for storing food. In particular, we like the Rubbermaid (model #6304; lids model #6509. (Nelson-Jameson, Inc) buckets. They have volume markers on the side, are sturdy and stackable, and have handles, so they are easy to carry around. We do punch holes into the lids for some air circulation. Another important feature of your buckets is that the walls should be high enough the frogs can't easily jump out (or they certainly will), but not unneccesarily high. To clean the buckets, we rinse them in 5-10% bleach in DI water solution, then rinse them in DI water thoroughly.
We use DI water. Tap water has chloramine and other toxins which are deadly to frogs. Therefore we use the lab DI water, and then add some rock salt (or just NaCl) or just use our Trop Colony water. For about four liters of DI water, we add roughly a quarter to a half a gram of rock salt (Fisher). Or more simply, we add a pinch of rock salt to a bucket of DI water. The frogs seem to do well in this frog water. We keep four to six frogs in a bucket with 2-4 liters of frog water. We don't use any special buffered water if we plan on doing a natural mating, in which case the embryos will be exposed to the frog water for some time. They seem to do fine with salt in DI water.
We house the frogs in a 24.5ºC incubator while they are out of the colony room (in the lab). If your lab doesn't maintain a stable temperature, we would recommend a 24-25ºC incubator for the frogs. The incubator also fulfills our IACUC requirements for a monitored environmental temperature and keeping the frogs out of public view.
It is important to keep laevis separate from tropicalis. Laevis harbor chytrid fungus, which can be deadly to trops. Therefore we use different buckets and avoid laevis water contamination into our trop buckets. See the Harland lab website Diseases Section for more information on chytrid infection.
Other useful things for the frogs in the lab include:
- hCG (Sigma) - controlled in some states(incl. CT), will need to comply with storage and recordkeeping requirements.
- 1 cc syringes
- 25 gauge or bigger needles for drawing up hCG
- 30 gauge needles for injecting hCG into the frogs
- paper towels for the burrito method of immobilizing frogs
- benzocaine, shears for decapitaion, tool for double pithing if needed
- tools (scissors and forceps) for dissecting out testis
- 1xMR + 0.2% BSA if you do IVF
- Eppendorf tube + plastic pestle for crushing testis
- plenty of 1/9xMR
- gentamycin at 100mg/ml (1000x)
- The frogs have generally done well in the lab. However, we have had some frogs die when their water has become fouled with dead and decaying eggs. Trops can lay many thousands of eggs. If these eggs are not fertilized(as when doing IVF), they will eventually decay and foul the water. We recommend changing the water 5 - 7 hours after the frogs start laying. Especially if you are expecting a large number of unfertilized eggs (after a planned in vitro fertilization, for example). Otherwise the frogs seem to do quite well.
Updated M. Lane 02/17