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Laboratory Husbandry

Frogs that are required for our experiments are brought to the lab and housed there until they are no longer needed and then returned to our Trop Colony.

In the lab, we house the frogs in plastic buckets. In general we have never seen any toxicity to the frogs from the plastic buckets. We use plastic containers that are designed for storing food. In particular we like the Rubbermaid (model #6304; lids model #6509. Obtained from Nelson-Jameson, Inc) buckets because 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 so the frogs can't easily jump out (or they certainly will) but not so high that they take up a lot of room in the lab. To clean the buckets, we just rinse them in DI water and a little bleach, and then rinse them in DI water thoroughly.

For a water source, we use DI water. The tap water in Berkeley has chloramine which is deadly to frogs. Therefore we use the lab DI water and then add some rock salt. 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 a pinch of salt in DI water.

Our lab maintains 22ºC pretty reliably. This is cooler than the temperature that we house the frogs in our Colony. However, we have not noticed any adverse effects of this temperature on the frogs for the few days (less than 5 days) that they are in the lab. If your lab, doesn't maintain a stable temperature, we would recommend a 22ºC incubator for the frogs. In fact in one case, a natural mating at 26ºC was unsuccessful (Hayes lab). When tried at 22ºC, it worked nicely. However, we have not tested this in a side-by-side comparison.

It is important to keep laevis separate from tropicalis. Laevis harbor chytrids which can be deadly to trops. Therefore we use different buckets and try to prevent laevis water contamination into our trop buckets. Our diseases section has more information on chytrid infection.

Other useful things for the frogs in the lab include:

hCG (Chorulon)
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
tools (scissors and forceps) for dissecting out testis
L15 Leibovitch's Media (either frozen or at 4C) (Sigma L5520)
Calf Serum (either frozen or at 4C)
eppendorf tube plastic pestle for crushing testis
plenty of 1/9xMR
gentimycin 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 and if three or four frogs in one bucket are laying then the number of eggs can be enormous. If these eggs are not fertilized, then they will eventually decay and foul the water. We recommend that after the frogs are induced to lay, the water be changed in the evening and the next day 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.

Contributed by Mustafa K. Khokha

Many thanks to the Grainger lab