which this perturbation comes about is through 
the insertional mutation of genes required for nor- 
mal morphologic development. Dr. Leder and his 
colleagues previously produced a transgenic inser- 
tional mutant that is defective in the normal path- 
way of limb development. Investigations of this mu- 
tant, limb deformity {Id), have led to the recent 
discovery a new Id allele, a suppressor mutation, 
1st, and to the cloning of the Id gene. A systematic 
effort has been made to discover new insertional 
mutants among the transgenic mice made for other 
experimental purposes. 
As the result of a systematic program of inter- 
crossing transgenic animals, a new mutation for 
PUBLICATIONS 
perinatal lethality was discovered and, using classi- 
cal genetic techniques as well as in situ analysis, 
was mapped to the distal portion of chromosome 
15. Homozygous animals are born and initially ap- 
pear normal, but die within 24 h; hence the name 
transgenic perinatal lethality (Tg.ple). Since the 
inserted fragment of DNA marks the locus at the 
molecular level, it should be possible to identify 
the responsible gene and understand the basis of 
this lethality, and thus gain insight into a potential 
cause of fetal wastage. 
Dr. Leder is also John Emory Andrus Professor of 
Genetics at the Harvard Medical School. 
Articles 
Beier, D.R., Morton, C.C., Leder, A., Wallace, R., and Leder, P 1989. Perinatal lethality (pie): a mutation 
caused by integration of a transgene into distal mouse chromosome 15. Genomics 4:498-504. 
Flanagan, J.G., and Leder, P. 1988. neu protooncogene fused to an immunoglobulin heavy chain gene re- 
quires immunoglobulin light chain for cell surface expression and oncogenic transformation. Proc Natl 
AcadSci [/5A 85:8057-8061. 
Nussenzweig, M.C., Schmidt, E.V, Shaw, A.C., Sinn, E., Campos-Torres, J. , Mathey-Prevot, B., Pattengale, PK., 
and Leder, P 1988. A human immunoglobulin gene reduces the incidence of lymphomas in c-Mj^c-bearing 
transgenic mice. Nature 336:446-450. 
Sarid, J., Benfey, PN., and Leder, P 1989. The mast cell-specific expression of a protease gene, RMCP II, is reg- 
ulated by an enhancer element that binds specifically to mast cell trans-acting factors. / Biol Chem 
264:1022-1026. 
Tepler, I., ShLmizu, A., and Leder, P 1989. The gene for the rat mast cell high affinity IgE receptor a chain. 
Structure and alternative mRNA splicing patterns. J Biol Chem 264:5912-5915. 
Tepper, R.I., Pattengale, P.K., and Leder, P 1989. Murine interleukin-4 displays potent anti-tumor activity in 
vivo. Cell 51 -.505-512. 
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