Dr. DeWitt Stetten, Jr. 
February 27, 1976 
Page 4 
difficult to isolate DNA from an insect without carrying along with 
it DNA from microorganisms; the hazard of such DNA to man and other 
organisms is unknown. For example. Drosophila, because of its 
plasticity in evolution and easy breeding, is one of the favorite 
organisms for genetic research. However, it is very difficult to 
separate Drosophila from yeast, and DNA extracted from Drosophila 
probably contains yeast DNA. 
In addition, literature exists dating back more than 10 years 
on the transmission of mycoplasma-like symbionts as a hereditary 
infection in Drosophila species. These symbionts are transmitted 
via the egg cytoplasm and enter the future germinal tissue of adult 
flies. Further, spirochetes that infect Drosophila eggs and alter 
the sex ratio of offspring have been described. A DNA virus able 
to infect and to multiply in these spirochetes is also known. Active 
virus has been extracted from Drosophila melanogaster , as well as 
from other species. Thus, it is very difficult to separate Drosophila 
DNA from the DNA of microorganisms that might remain associated 
with it even after prolonged breeding in the laboratory.* These 
are only a few instances of known association between microbes and 
insects. These associations may or may not have significance for man, 
but the insect class is so vast and so varied that the guidelines 
should consider it. There seems to be no biologic rationale for 
considering insects to be safer than cold-blooded vertebrates. This 
point was raised at La Jolla by Dr. Brenner, but the Committee voted 
to keep a distinction between the cold-blooded vertebrates and other 
cold-blooded animals, including insects. Because the Committee did 
Sakaguchi, B. and D. F. Poulson. Interspecific transfer of the 
"sex-ratio" condition from drosophila willistoni to D. Melanogaster. 
Genetics 48: 841, 1963. 
Oishi, K. and D. F. Poulson. A virus associated with SR-spirochetes 
of drosophila nebulosa . PNAS 67:1565, 1970. 
Ehrman, L. and R. P. Kernaghan. Infectious heredity in jforosophila 
paulistorum . A Ciba Foundation Symposium, 25-27 January 1972. 
Pathogenic Mycoplasmas. Associated Scientific Publishers, 
Amsterdam. 
Ehrman, L. and S. Daniels. Pole cells of ferosophila paulistorum : 
Embryologic differentiation with symbionts. Australian J. Biol. 
Sci. 28:133, 1975. 
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