DR L. CARO / SCIENCE PHOTO LIBRARY DR L. CARO / SCIENCE PHOTO LIBRARY
Transmission electron micrograph (TEM) of a male Escherichia coli bacterium (bottom left) conjugat- ing with two females. Sex between bacteria was discovered in 1946, & involves transfer of DNA. Maleness in E. coli is associated with long, hollow surface hairs called F-pili. This male has attached 2 F-pili to each of the females & DNA is transferred between them through their hollow cores. The tiny bodies that cover the F-pili are MS2 bacteriophages, a type of virus that attacks bacteria & binds specifically to F-pili. Magnification: x5000 at 35mm size, x35,000 at 8x10-inch size. Reference: MICROCOSMOS, figure 5.11, page 94.
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