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Horizontal gene transfer (HGT) refers to the transfer of genes between organisms in a manner other than traditional reproduction. Also termed ''lateral gene transfer'' (LGT), it contrasts with ''vertical transfer'', the transmission of genes from the parental generation to offspring via sexual or asexual reproduction. HGT has been shown to be an important factor in the evolution of many organisms. Horizontal gene transfer is the primary reason for bacterial antibiotic resistance,〔〔OECD, ''Safety Assessment of Transgenic Organisms, Volume 4: OECD Consensus Documents,'' 2010, pp.171-174〕 and plays an important role in the evolution of bacteria that can degrade novel compounds such as human-created pesticides and in the evolution, maintenance, and transmission of virulence. This horizontal gene transfer often involves temperate bacteriophages and plasmids. Genes that are responsible for antibiotic resistance in one species of bacteria can be transferred to another species of bacteria through various mechanisms (e.g., via F-pilus), subsequently arming the antibiotic resistant genes' recipient against antibiotics, which is becoming a medical challenge to deal with. Most thinking in genetics has focused upon vertical transfer, but there is a growing awareness that horizontal gene transfer is a highly significant phenomenon and among single-celled organisms perhaps the dominant form of genetic transfer. Artificial horizontal gene transfer is a form of genetic engineering. ==History== Horizontal gene transfer was first described in Seattle in 1951 in a publication which demonstrated that the transfer of a viral gene into ''Corynebacterium diphtheriae'' created a virulent from a non-virulent strain, also simultaneously solving the riddle of diphtheria (that patients could be infected with the bacteria but not have any symptoms, and then suddenly convert later or never),〔Phillip Marguilies "Epidemics: Deadly diseases throughout history". Rosen, New York. 2005.〕 and giving the first example for the relevance of the lysogenic cycle.〔André Lwoff (1965). ("Interaction among Virus, Cell, and Organism" ). Nobel Lecture for the Nobel Prize in Physiology or Medicine.〕 Inter-bacterial gene transfer was first described in Japan in a 1959 publication that demonstrated the transfer of antibiotic resistance between different species of bacteria. In the mid-1980s, Syvanen predicted that lateral gene transfer existed, had biological significance, and was involved in shaping evolutionary history from the beginning of life on Earth. As Jain, Rivera and Lake (1999) put it: "Increasingly, studies of genes and genomes are indicating that considerable horizontal transfer has occurred between prokaryotes" (see also Lake and Rivera, 2007). The phenomenon appears to have had some significance for unicellular eukaryotes as well. As Bapteste et al. (2005) observe, "additional evidence suggests that gene transfer might also be an important evolutionary mechanism in protist evolution." There is some evidence that even higher plants and animals have been affected and this has raised concerns for safety. It has been suggested that lateral gene transfer to humans from bacteria may play a role in cancer. Richardson and Palmer (2007) state: "Horizontal gene transfer (HGT) has played a major role in bacterial evolution and is fairly common in certain unicellular eukaryotes. However, the prevalence and importance of HGT in the evolution of multicellular eukaryotes remain unclear." Due to the increasing amount of evidence suggesting the importance of these phenomena for evolution (see below) molecular biologists such as Peter Gogarten have described horizontal gene transfer as "A New Paradigm for Biology". Some have argued that the process may be a hidden hazard of genetic engineering as it could allow transgenic DNA to spread from species to species.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Horizontal gene transfer」の詳細全文を読む スポンサード リンク
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