This summer some marmosets made the news- kreepy or kewl? you be
the judge...
Japanese scientists engineered the marmosets to make green
fluorescent protein in all the cells of their bodies, including
eggs and sperm. The marmosets are the first transgenic primates —
animals that carry a foreign gene. Some of the animals were able to
pass the foreign gene to offspring, the researchers report in the
May 28 Nature.
“It’s a great achievement,” says Shoukhrat Mitalipov, a
developmental biologist at the Oregon National Primate Research
Center in Beaverton. Other scientists have introduced foreign genes
in other primate species, but the genes were found in only some
tissues of the body and in some cases did not make protein, he
says.
The new work marks the first time scientists have successfully
introduced a foreign gene into all the cells of a primate, and the
first time the gene has produced its protein in all the body
tissues in a primate. More importantly, the marmosets are also the
first primates to transmit the gene to a next generation of
animals.
Being able to breed transgenic primates means having to do
expensive and difficult genetic engineering only once, then using
conventional breeding to make large numbers of transgenic
animals.
Transgenic marmosets can be used to study diseases and disorders
that affect higher brain structures, Mitalipov says. Specifically,
marmosets can model human neurodegenerative diseases, especially
those that are dominantly inherited — that is, diseases caused by
mutation in a single copy of the gene — says coauthor Hideyuki
Okano of Keio University School of Medicine in Tokyo. He plans to
use the transgenic marmosets to study Parkinson’s disease and
amyotrophic lateral sclerosis, also known as ALS or Lou Gehrig’s
disease.
Mice are currently used as models for many human diseases, but
are not ideal for studying brain disorders. “The mouse doesn’t give
the answers to all the questions we need answered,” Mitalipov says.
“There are lots of diseases that can only be modeled in
primates.”
Erika Sasaki of the Central Institute for Experimental Animals
in Kanagawa, Japan, and her colleagues injected a virus, called
lentivirus, into marmoset embryos. The virus carried the gene
encoding an enhanced version of green fluorescent protein or GFP,
which the virus inserts into the marmosets’ genome. The protein
glows green under UV light, so scientists could tell which embryos
had GFP inserted.
Sasaki and her colleagues implanted 80 embryos carrying the GFP
gene into 50 marmoset surrogate mothers. Only seven animals became
pregnant. Three of the surrogate mothers miscarried, but four of
the mothers gave birth to healthy infants — three had single babies
and one gave birth to twins. Four of the baby marmosets carry the
GFP gene and make the glowing green protein in at most of the
tissues the scientists tested, including blood, hair and skin. The
remaining marmoset doesn’t make GFP in its body, but did carry the
gene in its placenta.
A male transgenic marmoset named Kou passed the GFP gene on to
two offspring. One of the female transgenic marmosets also had two
transgenic babies, Sasaki says.
