Husbandry

Holding and producing conditions

How we keep and produce Xenopus tropicalis (October 2015)

SystemAquatic Ecosystems / Tecniplast - recirculating - with UV, particulate, mechanical and carbon filters.
Temperature25.5 oC (range 24-27 oC).
Conductivity800 uS (range 700-900uS).
pH7.9 (range7.5-9.0). pH maintained by Sodium Bicrbonate doses.
WaterPortsmouth Mains water. Conductivity maintained by a marine sea-salt.
Salt addedTropic Marin/Instant Ocean sea salt.
Tank size1.5-27 litres for adult frogs.1.5-16 litres for tadpoles.
Stocking density55 adult females per 27 litres (same sex tanks). 25-40 adult males per 27 litres.
Flow rate1.33 litres per minute in a 27 litres tank. Less flow in smaller tanks.
LightingFluorescent 13 hours light/11 hours dark with night light.
Environmental enrichmentDark coloured plastic guttering and downpipe tubes cut into 20 cm lengths. Artificial lily pads.

Feeding

AdultsSkrettine Horizon 23 trout pellets-fed 2-3 times per day, a couple of pellets per frog. 5 days/week.
FrogletsSkrettine Horizon 23 pellets-fed 2-3 times per day, a couple of pellets per froglet + fish food. 7 days /week.
TadpolesA filtered suspension of Rabma (Rabbit pellets) and Sanatogen (high protein powder) in system water. Alternatively sera micron algae.Fed 5 days per week, system water flow turned off while feeding.

All adult frogs are fed 5 days per week. All frogs may be given occasional supplements of lamb’s heart or similar, cut to appropriate size, especially for frogs with weight loss or non-competitors.

Ovulation

Females are primed with Chorulon 10 iu HcG in water, 16-72 hours before the eggs are required. A boosting dose of 100 iu is given as early as possible on the day the eggs are required. Egg laying starts normally 3-5 hours after the boosting dose and may last for several hours.

’Squeezes’ are restricted to 45 minute intervals. Males are sacrificed using Tricaine/MS222 for in-vitro fertilizations. Testes are removed and stored in L15/calf serum at room temperature. These should be used as quickly as possible as there is a dramatic loss in fertility when stored.

Mash 1 testis in L15/calf serum and add to squeezed eggs in a Petri dish using a pipette. Shake dish to ensure good mixing and create a single layer of eggs if possible. After 2-3 minutes flood with 0.05 x MMR or 0.1x MBS. All solutions used are warmed to room temperature, 20oC. Some labs use solutions at 4 degrees.

How we keep and produce Xenopus laevis (October 2015)

SystemTecniplast - recirculating - with UV, particulate, mechanical and carbon filters.
Temperature18.5 oC (range 17-19 oC).
Conductivity1550 uS (range 1500-1600uS).
pH7.9 (range7.5-9.0). ph maintained by Sodium Bicarbonate doses.
WaterPortsmouth Mains water. Conductivity maintained by a salt doser.
Salt addedTropic Marin/Instant Ocean sea salt.
Tank size27 litres.
Stocking density5-12 adult females per 27 litres (same sex tanks).
10-15 adult males per 27 litres.10-28 adult males per 27 litres.
Flow rate1.33 litres per minute in adult’s tanks, less flow in tadpoles tanks.
LightingFluorescent 13 hours light/11 hours dark with night light.

Feeding

AdultsSkrettine Horizon 23 pellets-fed 2-3 times per day, a couple of pellets per frog. 5 days/week.
FrogletsSkrettine Horizon 23 pellets-fed 2-3 times per day, a couple of pellets per froglet + fish food. 7 day/week.
TadpolesA filtered suspension of Rabma (Rabbit pellets) and Sanatogen (high protein powder) in system water. Fed 7 days per week, system water flow turned off when feeding.

All adult frogs are fed 5 days per week.

All frogs may be given occasional supplements of lamb’s heart or similar, cut to appropriate size, especially for frogs with weight loss or non-competitors.

How animals are assessed as suitable for re-use

Xenopus are individually identified by appropriate non-invasive methods such as digital photography and/or written descriptions of dorsal skin patterns or other distinguishing features. Plain frogs that are indistinguishable from each other are kept separate by placing them uniquely amongst small groups of others that are distinguished by pattern or colour.

This ability to track individuals is at the heart of our database driven reuse protocol, aimed at making judgements on Xenopus reuse more informed as it is based on the frog’s individual history and performance. The current protocol (although this may be subject to minor amendment) is:

There must be 3 months or 90 days between ovulations.

The following criteria must be considered when selecting frogs for reuse:

  1. General appearance: with your experience, you consider it likely to lay well.
  2. Skin texture: smooth and free from abrasions and redness.
  3. Body shape: consistent with history (known slim or plump frog).
  4. Body weight: consistency to be looked at.

Only if re-use is carried out.

  1. Body weight must be taken, compared with history and recorded on database.
  2. Person declaring fit to reuse must also record their details on database.