that long tracts of both genes are more than 80% 
similar. The RNA product of the H19 gene was not 
found associated with the translational machinery 
of the cell, but rather in an mRNP particle, reinforc- 
ing the conclusion that the RNA is not a classical 
mRNA. 
In situ hybridization studies have shown that the 
RNA product of the H19 gene is present at high lev- 
els in the majority of endoderm and mesoderm cell 
types in the mouse embryo but is completely 
absent from all ectodermal derivatives. By introduc- 
ing a mutated version of the H19 gene into the 
mouse germline, the laboratory has demonstrated 
that the DNA elements necessary for the endoderm 
and mesoderm expression can be functionally sepa- 
rated. Two endoderm-specific enhancers lie 8 kb 
pairs of DNA 3' to the gene itself The elements re- 
sponsible for mesoderm expression lie outside this 
domain. 
III. Analysis of Large Segments of the Mouse 
Genome. 
The laboratory is constructing a permanent li- 
brary of the mouse genome in yeast artificial chro- 
mosomes. The long-term goal of this project is to fa- 
cilitate the mapping and isolation of genes for 
which interesting developmental mutations exist, 
but which have not yielded to conventional molecu- 
lar genetic techniques. A second goal is to use the 
large segments of DNA as substrates for efficient ho- 
mologous recombination into the mouse germline. 
Dr. Tilghman is also Howard A. Prior Professor of 
the Life Sciences in the Biology Department at 
Princeton University and Adjunct Professor of Bio- 
chemistry at the University of Medicine and Den- 
tistry of New Jersey, Robert Wood Johnson Medical 
School. 
PUBLICATIONS 
Articles 
Camper, S.A., Godbout, R., and Tilghman, S.M. 1989. The developmental regulation of albumin and 
a-fetoprotein gene expression. Prog Nucleic Acid Res Mol Biol 36:131-143. 
Camper, S.A., and Tilghman, S.M. 1989. Postnatal repression of the a-fetoprotein gene is enhancer indepen- 
dent. Genes Dev 3:537-546. 
Godbout, R., and Tilghman, S.M. 1988. Configuration of the a-fetoprotein regulatory domain during devel- 
opment. Genes Dev 2:949-956. 
Yoo-Warren, H., Pachnis, V, Ingram, R.S., and Tilghman, S.M. 1988. Two regulatory domains flank the mouse 
H19 gene. Mol Cell Biol 8:4707-4715. 
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