Xenopus (Policy)

Policy: The IACUC has provided a set of guidance documents (Policies, Guidelines, and Informational Sheets) for use when planning animal procedures at the University of Iowa. An exception to a Policy must be described and justified in the Animal Protocol and approved by the full IACUC at a convened monthly meeting.

Purpose:  The purpose of this document is to describe when Xenopus species are covered by the Public Health Service Policy (PHS) on Humane Care and Use of Laboratory Animals.  In addition this document will describe when it is required for Xenopus to be housed in OAR facilities.  This document will also describe husbandry standards for Xenopus species housed in satellite housing areas.  This document is intended for use by researchers and research staff at the University of Iowa.

Requirement for Submission of an Animal Protocol¹

• Live embryonated eggs are only applicable to the PHS Policy once they hatch. Any Xenopus sp. used beyond Nieuwkoop and Faber stage (NF) Stage 36 (when hatching begins) requires an IACUC approved Animal Protocol
• Adult males and females producing/laying the eggs are covered by the Policy and thus require an IACUC approved Animal Protocol

Housing Location

• Housing of Xenopus beyond  Nieuwkoop and Faber (NF) stage 36 outside of OAR vivaria must be described in an Animal Protocol and approved by the IACUC
• Larval forms of frogs may be housed in the lab with prior IACUC approval until they are mature (i.e. hormone responsive)
• Housing within OAR vivaria is required once frogs are mature ²
  • Xenopus laevis (length from nose to cloaca):
    • 5-9 cm = males mature (hormone responsive);
    • 6.5-9+ cm (2.5-3.5+ inches) = females mature (hormone responsive)
  • Xenopus tropicalis:
    • > 6 months = adult (hormone responsive)

Husbandry Standards

• If unfamiliar with Xenopus husbandry protocols please contact an OAR veterinarian for guidance
• Embryos from NF stage 36-45
  • Appropriate water changes and monitoring will be performed by the lab
• Embryos up to feeding stage NF 45
  • Maintain in 0.3-0.1 X Modified Ringer’s Solution
  • Perform daily changes of Modified Ringer’s solution
• After feeding stage >NF 45 is reached
  • Feeding frequency:
    • X. laevis = 3 times per week
    • X. tropicalis = daily
  • Maintain in conditioned water
  • Water change frequency:
    • X. laevis = 3 times per week after feeding,  or more often if necessary
    • X. tropicalis = daily (usually 2 hours after feeding)
  • Maintain Temperature:
    • X. laevis = 16-22oC (usually ~18oC); 60.8-71.6oF (usually ~ 64.4oF)
    • X. tropicalis = 25oC (77oF)
  • A 12 hour light, 12 hour dark light cycle or a natural light cycle should be maintained

Record Keeping
For Xenopus greater than NF stage 45, a log/record will be kept in the room documenting the following:

• Room/enclosure temperature - must be recorded DAILY
• Water changes- each occurrence must be recorded
• Feeding of frogs – each occurrence must be recorded DAILY
• Observation of frog health - must be recorded DAILY
• Records must be kept indicating the age of Xenopus in any given container

References:
1.    http://grants.nih.gov/grants/olaw/faqs.htm
2.    https://www.enasco.com/c/Education-Supplies/Xenopus-Frogs

Last Reviewed by the IACUC 11/10/2021