ANDi (for “inserted DNA,” in a reverse transcribed direction) is a first transgenic rhesus monkey. It carries the GFP (green fluorescent protein) gene derived from the Jellyfish in every cell. The GFP gene was used, because it was known to be harmless and easily detectable.
Rhesus macaque as a model organism[]
The rhesus macaque is a widely used model organism, due to its easy upkeep in captivity and wide availability. The rhesus macaque is very close physiologically and anatomically to humans and is therefore extensively used in medical and biological research.
Macaque rhesus was used for development of vaccines against rabies, smallpox and polio. Currently it is used in drug testing for managing HIV/AIDS, understanding the female reproductive cycle and the development of the embryo and the propagation of embryonic stem cells.
The rhesus macaque were also one of the first organisms launched to space (experiments starting in the 1960s and 1970s) and first living beings to return alive.
In January 2000, the rhesus macaque became a became the first cloned primate (monkey Tetra).
Method[]
To produce ANDi Anthony Chan, Gerald Schatten and colleagues injected a genetically modified virus into unfertilized eggs of rhesus monkeys. 224 mature rhesus oocytes were injected with an retroviral vector pseudotyped with vesicular stomatitis virus envelope glycoprotein G (Figure 1).
Fig. 1. Injection of VSV-G pseudotyped retroviral vector, enclosing the GFP gene and protein, into the perivitelline space of mature rhesus oocytes. (A) Transmitted light and (B) epi- ßuorescence imaging of GFP carried within the vector particles
The GFP gene was carried either under the CMV promoter (strong viral promoter used in mamalian expression vectors) or the human elongation factor-1 alpha promoter (hEF-1a). Oocytes were cultured and subsequently fertilized by intracytoplasmatic sperm injection (ICSI ). Thereafter 40 of these embryos were transferred to 20 surrogates. Each of the surrogates carried two embryos. Among failed attempts, five pregnancies resulted in the births of three healthy males. Samples from hair, blood, umbilical cords, placentae, lymphocytes, buccal ephithelial cells and urogenital cells,were examined for transgene integration, transcription, and expression. This verification was performed by a polymerase chain reaction (PCR) with primers flanking either the vector or the GFP gene. Just one of the three newborns, ANDi, showed the presence of the trangene in all analyzed tissues (Figure 2). While ANDi appears to be normal and doesn't glow, the other two monkeys have exhibited fluorescence. In addition to PCR detection, further evidence was provided by GFP direct fluorescence in the toenails and hair of the fetus. Colocalization experiments in Figure two between direct GFP fluorescence and indirect anti-GFP immunocytochemi shown, that the GFP protein is found at direct fluorescent sources.
_Transgenic_rhesus_male_with_inserted_DNA.jpg){kind=link}
Fig. 2. (A) Transgenic rhesus male with inserted DNA. GFP expression was observed in hair shafts (B) and toenails (C) by direct epißuorescent examination in the male stillborn but not in the accessible tissues from ANDi. Immunostaining and epißuorescent examination of placental frozen sections from the male stillborn demonstrates the presence of the GFP protein. (D) Anti-GFP detection in placenta by rhodamine (red) immunoßuorescent microscopy. (E) GFP detection by ßuorescein (green) epißuorescence of the same section demonstrates the direct expression of the transgene. (F) Overlay of the green (E) and red (D) images demonstrates colocalization of direct GFP ßuorescence with anti-GFP imaging. Blue, Hoechst 33342 DNA staining. MagniŢcation in (D) through (F): 3400
Potential usage[]
This technique could be potentionally used to insert a human disease gene into a monkey. Since humans and the rhesus monkeys share roughly 95% genes, this would create a better way of studying various diseases, such as Alzheimer's , diabetes or breast cancer. Because monkeys are genetically closer to humans than mice, they could give scientists a better understanding of how diseases develop in people.
In addtion to this, modifying monkey DNA would eliminate the need to breed and select for animals with a desired phenotype.
Animal rights concerns + next step[]
Animal rights activists were very critical of this research, warning that although this research could medically benefit, it has to be subject under strict conditions.
"So now that scientist have put a jellyfish gene into a monkey, do they now want to insert a gene from a non-human animal into a human being? No, said Schatten. "We don't support any extension or extrapolation of this work from laboratory animals to humans".
References[]
Chan A.W.S., Chong K.Y., Martinovich C., Simerly C., Schatten G., Transgenic Monkeys Produced by Retroviral Gene Trasnfer into Mature Oocytes. Science, 291:309 - 312 (2001)