Grainger Lab
X. tropicalis Adult Husbandry Protocol
Updated June 1, 2001
Basic Care for
Adults
All post-metamorphic animals are considered adults
and receive essentially the same care, with certain significant differences
to
accommodate very young froglets.
Animals are kept in 120 liter black, fiberglass tanks (see Grainger/Keller
Frog Facilities document) filled with approximately 100 liters of well water.
Animals are fed and cleaned three times weekly and are checked every day.
Three critical
parameters
that we have found to have a significant effect on growth rate, egg quality,
and general health are: diet, density, and temperature.
Diet
Feeding should be done 3 to 4 hours before the tanks
are to be cleaned. This interval gives the animals a chance to digest their
food. Cleaning too soon after feeding can result in the animals regurgitating
a large amount of what they have eaten.
We feed all of our frogs post-metamorph size #5 NASCO
pellets (NASCO: 1-920-568-5565) in amounts relative to the number and size
of frogs in a given tank. As a general rule of thumb, feed an amount of food
that can be almost completely consumed by the frogs in 2 to 3 hours. This
will obviously require some experimentation and will vary from tank to tank.
We use the post-metamorph size for all frogs because it is easily ingested
by even the smallest froglets and the small pellets go down the drain more
readily.
We have experimented with several alternative foods
and feeding schedules to determine their effects on growth rate. Our greatest
success has come by combining pellets with live California blackworms and
feeding 6 times a week. Using this regimen we have obtained frogs that are
sexually mature at 31/2 months of age. The worms are
purchased in bulk (5lbs. or more) from Aquatic Foods (Fresno, CA 1-559-291-0623)
or they can usually be obtained in smaller quantities from a local pet store.
Although we are aware of the arguments against using live food, we find no
apparent increase in disease or ill health in these frogs while the increase
in their rate of growth is substantial.
We have also tried freeze-dried bloodworms (Aquatic
Ecosystems, 800-422-3939) and Repto-Min pellets (Tetra Inc., 800-526-0650),
but the frogs don't seem to like them and won't eat them unless they are starved
of other foods.
Density
Crowded tanks clearly have an adverse effect on the
growth rate of young froglets, and density experiments are ongoing. As a general
rule of thumb, the less crowded a tank is the faster the animals will grow.
Since our facility is already crowded, only animals that are important to
ongoing experiments are placed in low-density tanks. For mature animals, we
try to maintain a density between 1 and 2 frogs per liter.
Temperature
Froglets and adults are kept in 24-25°C water. The
air temperature in the rooms is set 1 to 2°C above the desired water temperature
to offset the effects of evaporative cooling. This temperature appears to
be optimal for good egg quality in females, particularly for applications
such as transgenesis.
Exposure of adult animals to temperatures below 22°C
for several months may cause an increased susceptibility to disease and should
be avoided, although short-term exposure (i.e. taking animals up to the lab
for egg collection) appears harmless.
Cleaning
All frog tanks are cleaned 3 times per week (usually
Tu, Th, Sat). Tanks are drained, leaving an inch or two of water in the bottom,
and uneaten food is swept down the drain. The tank walls and floor are gently
scrubbed and rinsed down and then the tank is refilled. The tank scrubbers
are treated with ethanol and rinsed between each tank. We use drain covers
with 1/4" holes in adult tanks and 1/8" holes in froglet tanks.
When draining tanks containing young (< 2 month) froglets, we place a metal
colander upside-down over the drain to prevent froglets from being injured
by the strong suction.
We are not currently using salt or phosphate to supplement
the well water in our frog facility, although we will supplement tanks containing
sick animals. Healthy animals seem
to be fine in unbuffered well water (pH about 5.8). The recipe for salt/phosphate buffering solution
follows. For sick or injured animals, the final concentration of salt in each
tank should be 1 g/L. The water is
buffered with phosphate to pH 6.5-7.2 (~1.89mM).
For 2 (100 liter) tanks:
210g rock
salt (we use the type made for water softeners)
56.4g
dibasic sodium phosphate
in 3600
ml distilled, deionized water
Add 1800 ml of the
above solution to each tank.