Chimpanzee Genome
569
their expression pattern in humans or
chimpanzees comprise candidates for phe-
notypic differences between both species
and thus, should be the subject of compar-
ative studies as described in the previous
section (Sect. 3.2).
4
Chimpanzees in Biomedical Research
T
h
ec
u
r
eo
rp
r
e
v
e
n
t
i
o
no
fd
i
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a
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si
s
one of the major interests in human
research. In the study of disease-causing
processes on the cellular and molecular
level, nonhuman primates in general,
and chimpanzees in particular, can be
regarded as important model organisms.
Their similarity to humans renders them
susceptible to a number of pathogens
correlated with human diseases. Thus,
the infection of primates under controlled
laboratory conditions allows the study of
the onset and progress of the respective
disease with a resolution far beyond what
can be achieved by observatory studies in
humans. Furthermore, as a result of the
growing understanding of disease-causing
processes, new therapeutical strategies
and medicines will be developed that
speci±cally target individual pathways in
the human metabolism. Therefore, the
traditional model organisms that are rather
distantly related to humans may no longer
be suitable to test the ef±cacy and safety of
these medicines. Rather, model organisms
such as the chimpanzee are required that
resemble the human metabolism as closely
as possible. Eventually, certain human
diseases and pathogens appear to affect
chimpanzees either to a lesser extent than
humans, or not at all. The identi±cation
of the underlying molecular basis of this
reduced susceptibility will provide starting
points for new therapeutical approaches to
cure the respective disease.
4.1
Are Chimpanzees Good Model Organisms?
The arguments listed above comprise a
clear vote for a wide use of chimpanzees
in biomedical research. Accordingly, nu-
merous research facilities founded chim-
panzee colonies, and in the 1980s, breed-
ing programs were started to insure that
enough chimpanzees were available for
research needs. However, it appears that
the similarity between chimpanzees and
a (hypothetical) good model organism for
biomedical research is very limited. Such
an organism would be rather mouse-sized
thanch
imp
-s
ized
.No
ton
lyistha
tdes
i
r
-
able due to the limitation of laboratory
space and budget for food, it also greatly
facilitates handling of the animals during
the experiments. Who ever has seen some-
body pulling chimps by their tail out of
th
ec
ag
e
?Andth
i
si
sno
tb
e
c
au
s
eth
e
i
r
tails are pretty much nonexisting! Further-
more, a good model organism would have
a generation time and a life span substan-
tially shorter than that of chimpanzees.
The bene±ts would be twofold. First, it in-
creases the value of the model organism for
research on transgenic animals. The spe-
ci±c inactivation of genes in an organism
(knockout) as well as their overexpres-
sion or exchange with functional homologs
from other species (knockin) gains increas-
ing importance in the study of function
and evolution of genes and gene products.
A minimal time span between the ge-
netic modi±cation of the individual – this
generally happens at a very early stage
in development – and the latest possible
observation of the corresponding pheno-
typic effect is desirable for both kinds of
studies. The latter time point is obviously
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