Masters Theses


Ling Li

Date of Award


Degree Type


Degree Name

Master of Science


Life Sciences

Major Professor

Dabney K. Johnson

Committee Members

Brynn H. Voy, Naima Moustaid-Moussa


The large-scale mouse mutagenesis experiments conducted at Oak Ridge National Laboratory using mouse specific-locus test (SLT) have generated numerous radiation- or ENU-induced mutations. A series of mutations were mapped near the p gene, one of the seven marker loci in mouse chromosome 7. Complementation analyses with a panel of p deletions have defined a number of “functional units”, among which is l7Rl1, a ~300kb region corresponding to human chromosome 11p14-p15 and containing four genes (from centromere to telomere): tubulin gamma associated protein 5 (Tubgcp5), Cytoplasmic fragile X mental retardation syndrome 1 homolog (FMR1) interacting protein 1 (Cyfip1), non-imprinted in Prader-willi/angelman syndrome 2 (Nipa2), and non-imprinted in Prader-willi/angelman syndrome 1 (Nipa1). l7Rl1 is known to be required for periimplantation survival, but it has been unclear how any one of the deleted genes contributes, if at all, to the implantation failure. In this study, we continued the study of the l7Rl1 by exploiting the DNA sequence and mutation resources available for this region of the mouse genome. Cyfip1 is the first candidate gene among the four to cause the peri-implantation lethal phenotype. To study the function of Cyfip1, Cyfip1Gt/+ transgenic mice were generated using a gene-trap ES cell line from the BayGenomics gene-trap ES cell library. However, Cyfip1Gt/Gt homozygotes do not show periimplantation lethality. Instead, the Cyfip1Gt/Gt homozygous embryos are able to survive through the peri-implantation stage (E4.5-E6.5) and develop normally until E8.5, after which the embryonic development is arrested with defects in the central nervous system. Two N-ethyl-N-nitrosourea (ENU)-induced lethal mutation stocks, l7Rl1ENU2R and l7Rl1ENU3R have been previously mapped within the l71Rl critical interval. We performed intra- and inter-crosses for these two ENU-induced mutations as well as allelism tests with Cyfip1Gt/+ mice. We have identified the two ENU mutations at the molecular level and confirmed that they are alleles of Cyfip1. The results suggest that Cyfip1 plays an indispensable role in mouse embryonic development. Therefore, if the l7Rl1 is a singlegene defect, Cyfip1 is an unlikely candidate. However, it may still be a contributor to the l7Rl1 lethal phenotype if the peri-implantation lethality is due to the combinatorial effects of several gene deficiencies.

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