Glowing discovery. These baby marmosets are home to a foreign gene introduced first in their parents
Hideyuki Okano / Keio University. Erika Sasaki / CIEA
marmosets whose skin turns green under ultraviolet light can take a big role in the study of aging and neurodegenerative diseases in humans. A Japanese team introduced the gene for green fluorescent protein (GFP), a biomarker widely used in the smallest monkeys in the world and found the gene in the next generation of animals. Get introduced gene to pass from mother to offspring is a first in a non-human primate and is a step to breeding colonies with marmoset human disorders.
mouse Researchers engineering, rats, pigs and other animals for transporting the mutant genes that cause a variety of human diseases. But these animals are not quite like people to effectively model human aging and neurodegenerative diseases. There has been some success in the transfer of genes in monkeys ( Science NOW, May 19, 08), but these transgenic animals either died young or failed to transmit genes to their offspring.
In the new study, Hideyuki Okano, a neuroscientist at the Keio University School of Medicine in Tokyo, and colleagues turned to marmosets. At about 20 centimeters high, the creatures are smaller than the other monkeys and cheaper to handle and at home. Marmosets are also more fertile: Mature females in 12 to 18 months and can withstand 4-6 children per year. Yet Okano's team had to overcome some obstacles.
The first was tweaking the standard gene transfer procedures. To add a new gene to a fertilized egg, researchers typically injected a virus carrying the gene into the space between the egg and a protective membrane that surrounds it; the virus then transfers the gene into egg cells. Okano and his team have made this process more efficient by placing the egg and the membrane in a chemical soup that caused the oocyte to shrink, thereby creating a vacuum inside of the membrane they could then fill of several virus particles carrying the gene for GFP.
The second improvement hinged on good timing. Once a gene is added to a fertilized egg, the transgenic embryos obtained must then be quickly placed in the stomachs of substitution of monkeys are at an optimum time in their menstrual cycles. The researchers found that they can control breeding cycles marmosets more effectively than other monkeys. This meant the team could relatively easily Okano have enough substitutes ready to receive the embryos just the right time.
The researchers injected the GFP gene into 91 marmoset embryos. They then implanted the embryos into 50 surrogate mothers, some of whom received multiple embryos. Four surrogates produced a total of five living descendants, all carrying the GFP gene as indicated by exposure of the skin to ultraviolet light, which causes it to glow, and using sophisticated genetic methods to confirm the presence of gene. One of these marmosets grew, apparently healthy, and finally produced a baby also carrying the GFP gene, reports the team in Okano Nature tomorrow .
In theory, researchers can now repeat the experiment, the addition of genes responsible for human diseases, such as those causing amyotrophic lateral sclerosis and Parkinson's disease (also known as disease name Lou Gehrig's disease). "This represents a step forward in the development of [animal] most appropriate models for human disease," says Thaddeus Golos, a reproduction biologist at the Research Centre of the Wisconsin National Primate in Madison. The marmoset has limits, however . rhesus macaques and other monkeys are genetically more similar to humans in a way that may be important for the study of metabolic and endocrine disorders, said Golos. and Okano emphasized that the virus of his team used in this experiment can carry that relatively small genes in embryos. as such, the technique must be modified for larger genes, such as one that causes muscular dystrophy.
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