horizontal gene transfer

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Related to Horizontal DNA transfer: vertical gene transfer

horizontal gene transfer

The transfer of genetic material from one organism to another by a process other than reproduction, as in the conjugation of bacteria. Also called lateral gene transfer.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

horizontal gene transfer

the transfer of genetic material directly from one organism to another by various processes, without REPRODUCTION. Natural agents, including VIRUSES and PLASMIDS, can transfer genes horizontally between individuals. These enter cells and multiply within them either extrachromosomally or integrated into the GENOME. In BACTERIA, horizontal gene transfer is mediated by the naturally-occurring processes of CONJUGATION, TRANSDUCTION and TRANSFORMATION. The transfer process brings about the spread of new genes within and between populations, allowing adaptation to a changing environment. Broad host range transfers involve members of different species/genera, whilst those between closely related bacteria are narrow host range.

The rapid emergence of antibiotic-resistant bacteria is largely a consequence of horizontal gene transfer. The process is viewed as a major driving force in EVOLUTION.

Transfer of natural agents is limited by various barriers that counter gene flow, such as INCOMPATIBILITY, restriction (see MODIFICATION AND RESTRICTION SYSTEM), lack of appropriate RECEPTORS and inactivation of the genetic material or host. However, artificial vectors, constructed by combining parts of various natural agents, have been designed to overcome such barriers. Horizontal gene transfer is also called lateral gene transfer. Compare VERTICAL GENE TRANSFER.

Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
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As already noted, bacteria are resistant to antimicrobial drugs after horizontal DNA transfer or mutations.

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