Viability E18.5 Secondary Screen IMPC_EVP_001

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Purpose

To assess the viability, sub-viability, and lethality of homozygous embryos at E18.5

Experimental Design

  • Set up timed matings with heterozygous mice
  • Day 0 is defined as the midpoint of the prior dark cycle following the identification of a copulation plug.
  • Collect embryos at E18.5
  • Collect tissue and genotype embryos.

Procedure

  1. Set up timed mating with heterozygous animals. Aim to dissect and collect >=28 alive embryos, otherwise lethal and subviable calls cannot be made. If more than three homozygous pups are produced before 28 pups are genotyped, a viable call can be made.
  2. Collect tissue for genotyping and (OPTIONAL) score Gross Morphology and/or process for Histopathology and or Imaging.
  3. Genotype all embryos and
    1. Strains that produce NO existing homozygous embryos will be considered LETHAL (complete embryonic lethality [MP:TBC]).
    2. Strains that produce NO live (absence of heartbeat) homozygous embryos will be considered LETHAL (complete embryonic lethality [MP:TBC]).
    3. Strains that produce live homozygous embryos but with an obvious defect will be left to the discretion of the center with the decision and reason recorded in the parameters.
    4. X-linked strains that produce NO live hemizygous male embryos from female carriers will be considered LETHAL (complete embryonic lethality [MP:TBC]).
  4. Flag strains that produce less than normal numbers of homozygous/hemizygous male progeny
    1. Strains that produce <50% expected homozygous progeny will be annotated as partial embryonic lethality [MP:TBC].
    2. X-linked strains that produce <50% expected male hemizygous progeny from female carriers will be considered partial embryonic lethality [MP:TBC].

Notes

Data QC

All genotypes should be collected using validated assays.

Y chromosome assay required for X-linked lethal strains.

Data Analysis, annotation and display (+statistics)

Preliminary: No analysis required as it is a line level procedure. This could change with additional data about the procedure.

See E18.5 Gross Morphology protocol for MP calls of specific phenotypes at this time point.

Total Embryos: All, WT, Het, Hom
    •Alive, dead, and defect (all genotyped)
Total Dead: All, WT, Het, Hom
    •Dead  call difficult can’t always see heart beating (E18.5)
Total Defect (Alive or Dead):  All, WT, Het, Hom
    •Abnormal and dead embryos
Litter size: all genotyped embryos
    •ignore partials and reabsorptions.

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