lateral gene transfer

lateral gene transfer - Offspring are known to inherit...

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Offspring are known to inherit genes which their parents have. This “transfer” of genetic material to offspring, or the foreseeable inheritance of genes by subsequent generations, is an essential basis of the evolutionary process. This is known informally as vertical gene transfer, a naturally, common occurring phenomena in the field of genetics. Until recently, this was the only known method of passing down genetic information, through reproduction. In 1959, a stunning breakthrough in Japan was made concerning the field of genetics. Yamanaka Ochiai’s paper “Inheritance of drug resistance (and its transfer) between Shigella strains and between Shigella and E.coli strains” described a new occurrence in gene transfer. It became possible that an organism can transfer its genetic information to another organism that is not the donor’s direct offspring. Initially, the paper’s prime objective was to inform Japanese workers in regards to multiple drug resistance in several bacteria. The facility with which certain bacteria attained similar resistance to the same spectra of antibiotics, which in turn indicated that the resistance traits were being transferred amongst the taxa, rather than being generated de novo by each individual lineage. Thus the biology of lateral gene transfer had been discovered. Lateral gene transfer is defined as the process in which an organism transfers genetic material to another organism which is not its offspring. This includes uptake of foreign naked DNA by bacteria (transformation), the utilization of a vector (bacteriophage) to transfer bacterial DNA into another bacterium (transduction), and by bacterial conjugation which is the transfer of genetic material between bacteria through direct cell-to-cell contact. Even though Lateral Gene Transfer has been proven to be an important method for prokaryotes to transfer genes to other prokaryotic organisms, there are still various disparagements in regards to this method. The primary criticism of many of the approaches for identifying cases of Lateral Gene Transfer is the fact that the observations can
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also be explained by several other reasons, one of which being an inaccurate phylogenetic reconstruction method. Also gene loss in multiple lineages can occur, as well as novel sequences arising from the divergence of gene duplications, and varying mutation rates for different proteins. Some strategies for identifying LGT are observational in nature, and evidence obtained for LGT may be prone to investigators’ biases or can be explained by statistical error. Although the widespread impact of lateral gene transfer on bacterial evolution was not appreciated until much later, these early studies of rapid evolution by gene acquisition encompass four issues relevant to all current studies. One such issue is determining whether one has the ability to directly detect as well as identify cases of lateral gene transfer. Also, can one determine where exactly the transferred genes arise from, and by what mechanisms are they able
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This note was uploaded on 04/18/2008 for the course BIO 312 taught by Professor Car during the Fall '07 term at SUNY Stony Brook.

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lateral gene transfer - Offspring are known to inherit...

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