Phenotypes associated with this allele

• Allele Symbol: Mrc1^tm1Jub
• Allele Name: targeted mutation 1, Jacques U Baenziger
• Allele ID: MGI:2656742
• Summary: 2 genotypes

Jump to	Allelic Composition	Genetic Background	Genotype ID
hm1	Mrc1^tm1Jub/Mrc1^tm1Jub	involves: 129X1/SvJ * C57BL/6J	MGI:2656743
ht2	Mrc1^tm1Jub/Mrc1^+	involves: 129X1/SvJ * C57BL/6J	MGI:2656744

Genotype
MGI:2656743

hm1

• Allelic Composition: Mrc1^tm1Jub/Mrc1^tm1Jub
• Genetic Background: involves: 129X1/SvJ * C57BL/6J

• ♀: phenotype observed in females
• ♂: phenotype observed in males
• N: normal phenotype

mortality/aging

embryonic lethality between implantation and somite formation, complete penetrance ( J:74332 )

• homozygotes generated by heterozygous intercrosses die in utero prior to E6.5

Genotype
MGI:2656744

ht2

• Allelic Composition: Mrc1^tm1Jub/Mrc1⁺
• Genetic Background: involves: 129X1/SvJ * C57BL/6J

reproductive system

impaired embryo implantation ( J:74332 )

♀ • females heterozygotes ovulate normally but display a reduced rate of implantation relative to wild-type females

♀ • the mean number of embryos implanted in female heterozygotes vs wild-type females is 5.1 and 8.7, respectively

♀ • exogenous administration of progesterone and estrogen increases the mean number of embryos implanted in female heterozygotes to 7.1, which is not significantly different from that of wild-type females

decreased litter size ( J:74332 )

• when females heterozygotes are bred with either wild-type or heterozygous males, the median number of pups per litter is reduced to only 5 pups vs the 8-9 pups obtained when wild-type or heterozygous males are bred to wild-type females

• only 15-20% of litters born to heterozygous females fall within the normal range of litter size for wild-type females, with most litters containing 1-5 pups

• however, no significant differences in average litter size are observed between crosses of female heterozygotes male heterozygotes (4.7 pups/litter) and female heterozygotes x wild-type males (5.2 pups/litter)

homeostasis/metabolism

abnormal circulating estrogen level ( J:74332 )

• female heterozygotes fail to exhibit the expected transient rise of estrogen levels normally observed prior to implantation, due to delayed LH clearance from the circulation

increased circulating luteinizing hormone level ( J:74332 )

• at implantation, female, but not male, heterozygotes display a 4-fold reduction in the clearance rate of LH from the circulation: the circulatory half life of LH is increased to 2.04 min in heterozygotes from 0.47 min in wild-type mice

• as a result, circulating LH levels remain elevated for longer periods of time and have an apparent impact on the endocrinologic state of the female that alters the levels of estrogen produced at the time of implantation