Science Frontiers, no. 25: Jan-Feb 1983


Up until now, the three genetic systems were thought to be discrete, each going down its own pathway. But chloroplasts genes have now been found inside plant mitochondria, overturning conventional wisdom. To sum it all up, DNA seems promiscuous — no respecter of privacy and breaking down all isolating genetic barriers.  (Ellis, John; "Promiscuous DNA — Chloroplast Genes inside Plant Mitochondria," Nature, 299: 678, 1982.)

Science Frontiers, no. 34: Jul-Aug 1984


It was a surprise when DNA sequences from mitochondria in yeast cells were discovered setting up shop in the nuclear genomes (i.e., the normal genetic endowment of the cell nucleus). Now biologists find that DNA sequences in many species regularly and frequently hop from one genome to another. Genetic material from cell chloroplasts mix with that of the mitochondria and that of the normal nucleus in what seems to be a free-for-all. This genome hopping has earned DNA the adjective "promiscuous." (Lewin, Roger; "No Genome Barriers to Promiscuous DNA," Science, 224:970, 1984.)

Comment. The promiscuity of DNA raises speculation that other DNA-bearing entities that invade the body, especially the viruses, may transfer their DNA to the host, and conceivably vice versa. With DNA apparently much more promiscuous than believed earlier, the role of disease in the development of life takes on a new importance. In other words, all species can potentially exchange genetic information with all others. In fact, in a broad sense, sperm are infectious agents, and pregnancy a disease! DNA will stop at nothing to spread itself around.— William R. Corliss