Genetics

Genetic Transfer Sighted

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Science  10 Aug 2012:
Vol. 337, Issue 6095, pp. 624
DOI: 10.1126/science.337.6095.624-b
CREDIT: INGRAM PUBLISHING/THINKSTOCK

In the early 1950s, Martha Chase and Alfred Hershey used radioisotope labeling of the protein and DNA of a bacteriophage to show that DNA, rather than the proteins that they expected, facilitated the transfer of genetic information for new phage replication within a bacterial cell. Van Valen et al. now report visual confirmation, in real time, of single fluorescently labeled molecules of DNA from bacteriophage lambda being ejected into live Escherichia coli cells. The authors' method reveals properties of the DNA ejection event that differ from those measured by in vitro detection of DNA ejected from phage artificially treated with a bacterial outer membrane protein. Transfer to the live cell took several minutes—10 to 100 times longer than had been observed in vitro. Further characterization of variable timing of the transfer, pausing during transfer, and rates of transfer in relation to the amount of DNA transferred begin to shed light on fundamental aspects of the process that remain mysterious. Specifically, they increase our understanding of the relative extent to which transfer is promoted by molecular motors, by the energy of compaction of the DNA in the bacteriophage capsid, or by events within the bacterial cell.

Curr. Biol. 22, 1339 (2012).

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