transgenic chicken to aid study
of embryo development
Researchers in the College
of Agriculture and Life Sciences’ Department
of Poultry Science have developed a powerful new tool to aid the
understanding of how chicken embryos develop.
The research of Dr. Paul
Mozdziak, assistant professor of poultry science, and Dr. James Petitte,
professor of poultry science, resulted in successfully transferring
a gene into a chicken and establishing a line of chickens carrying that
specific marker gene.
Currently, the chick embryo
is often used as a model to understand normal and abnormal embryo development.
The new lines of transgenic chicken provide a new tool that can be employed
in studies aimed at understanding birth defects such as limb deformities
and spina bifida. The researchers say learning the mechanisms behind
how cells behave during embryo development could eventually provide
clues to halting developmental disabilities and may lead to other uses
not yet imagined, including improvements in human and animal health.
The research appears in
the March edition of Developmental Dynamics.
“Although there are
people who have made transgenic chickens before, no one has produced
a transgenic chicken expressing a reporter gene that can be easily tracked,”
Mozdziak says. “We can now take cells from our transgenic chicken
and put those cells into a chick embryo or another transgenic chicken
and see how the cells behave and interact with each other.”
Petitte says, “This tool provides the impetus to go to the next
level of looking at avian stem cells in embryos, putting these stem
cells in different places and seeing where they end up.”
The researchers say gene
transfer is much more complicated in chickens than in, say, mice. Chicken
embryos contain about 50,000 cells before the egg is laid; gene transfer
in other mammals involves inserting DNA into just one cell.
Mozdziak and Petitte developed
the transgenic chicken by taking an RNA virus, or retrovirus, carrying
a reporter gene – the lacZ gene, which is easy to detect and which
expresses a protein, beta-galactosidase – and injecting it into
the blastoderm, or layer of cells on the surface of the yolk, of freshly
laid chicken eggs. The eggs were allowed to hatch, and chickens were
screened for the presence of the lacZ gene. Eight of 15 male chickens
that lived to sexual maturity carried the lacZ gene in their semen,
the researchers say.
These eight chickens were
then mated with female non-transgenic chickens. Of the chicks produced,
two males tested positive for the lacZ gene. These two males were mated
with normal females and 50 percent of their offspring contained the
lacZ gene as expected.
Further, the second-generation
chickens expressed beta-galactosidase, and the lacZ gene is apparently
stable from generation to generation.
Petitte says that other
transgenic chickens have carried the lacZ gene but that this is the
first time a transgenic chicken line that expresses beta-galactosidase
has been developed.
“This is a really powerful
research tool,” he said, “and it’s the first time anyone
has had this tool in avian biology.”
—Mitch
Kulikowski, NCSU News Services
