Lateral gene transfer

Examples of Lateral gene transfer in the following topics:

• Unclassified and Uncultured Bacteria

  • This uncertainty resulted from the lack of distinctive structures in most bacteria, as well as lateral gene transfer that occurred between unrelated species.
  • Because of the existence of lateral gene transfer, some closely related bacteria have very different morphologies and metabolisms.
  • To overcome these uncertainties, modern bacterial classification emphasizes molecular systematics, using genetic techniques such as guanine cytosine ratio determination, genome-genome hybridization, as well as sequencing genes that have not undergone extensive lateral gene transfer, such as the rRNA gene.

• Phylogenetic Analysis

  • This uncertainty was due to the lack of distinctive structures in most bacteria, as well as lateral gene transfer between unrelated species.
  • As more genome sequences become available, scientists have found that determining these relationships is complicated by the prevalence of lateral gene transfer (LGT) among archaea and bacteria.
  • Due to lateral gene transfer, some closely related bacteria can have very different morphologies and metabolisms.
  • To overcome this uncertainty, modern bacterial classification emphasizes molecular systematics, using genetic techniques such as guanine cytosine ratio determination, genome-genome hybridization, as well as sequencing genes that have not undergone extensive lateral gene transfer, such as the rRNA gene.
  • This approach is expected to have an increased resolving power due to the large number of characters analyzed and a lower sensitivity to the impact of conflicting signals (i.e. phylogenetic incongruence) that result from eventual horizontal gene transfer events.

• Phenotypic Analysis

  • This horizontal gene transfer, coupled with a high mutation rate and many other means of genetic variation, allows microorganisms to swiftly evolve (via natural selection) to survive in new environments and respond to environmental stresses.
  • These plasmids can be transferred between cells through bacterial conjugation.
  • This uncertainty was due to the lack of distinct structures in most bacteria, as well as lateral gene transfer between unrelated species.
  • Due to lateral gene transfer, some closely related bacteria can have very different morphologies and metabolisms.
  • To overcome this uncertainty, modern bacterial classification emphasizes molecular systematics, using genetic techniques such as guanine cytosine ratio determination, genome-genome hybridization, as well as sequencing genes that have not undergone extensive lateral gene transfer, such as the rRNA gene.

• Diverse Cell Forms of Methanogens

  • Therefore, the large numbers of proteins uniquely shared by all methanogens may be due to lateral gene transfers.
  • It was the first archaeon to have its complete genome sequenced, identifying many genes and synthesis pathways unique to the archaea.

• Gene Transfer in Archaea

  • This phenomenon is described as horizontal gene transfer.
  • Horizontal gene transfer (HGT) refers to the transfer of genes between organisms in a manner other than traditional reproduction.
  • Also termed lateral gene transfer, it contrasts with vertical transfer, the transmission of genes from the parental generation to offspring via sexual or asexual reproduction.
  • Archaea show high levels of horizontal gene transfer between lineages.
  • Taken together it is clear that gene transfer happens in Archaea, and probably is similar to horizontal gene transfer seen in the other domains of life.

• Archaeoglobus

  • However, the possibility that the shared presence of these signature proteins in these archaeal lineages is due to lateral gene transfer cannot be excluded.
  • The complete genome sequence from Archaeoglobus fulgidus reveals the presence of a complete set of genes for methanogenesis.
  • The function of these genes in A. fulgidus remains unknown, and the lack of the enzyme methyl-CoM reductase does not allow for methanogenesis to occur by a mechanism similar to that found in other methanogens.
  • One observation about the genome is that there are many gene duplications and the duplicated proteins are not identical.
  • The duplicated genes also gives the genome a larger genome size than its fellow archaeon M. jannaschii.

• Pathogenicity Islands and Virulence Factors

  • Pathogenicity islands (PAIs) are a distinct class of genomic islands acquired by microorganisms through horizontal gene transfer.
  • Pathogenicity islands (PAIs) are a distinct class of genomic islands acquired by microorganisms through horizontal gene transfer.
  • Cryptic mobility genes may also be present, indicating the provenance as transduction.
  • PAIs are transferred through horizontal gene transfer events such as transfer by a plasmid, phage, or conjugative transposon.
  • They may be located on a bacterial chromosome or may be transferred within a plasmid.

• Pathogenicity Islands

  • Pathogenicity islands (PAIs) are a distinct class of genomic islands acquired by microorganisms through horizontal gene transfer.
  • Cryptic mobility genes may also be present, indicating the provenance as transduction.
  • They are transferred through horizontal gene transfer events such as transfer by a plasmid, phage, or conjugative transposon .
  • They may be located on a bacterial chromosome or may be transferred within a plasmid.
  • Pathogenicity islands are transferred horizontally, this details some of the ways that occurs.

• Inactivating and Marking Target Genes with Transposons

  • Transposons allow genes to be transferred to a host organism's chromosome, interrupting or modifying the function of a gene.
  • Insertional mutagenesis is a technique used to study the function of genes.
  • In bacteria, transposons can jump from chromosomal DNA to plasmid DNA and back, allowing for the transfer and permanent addition of genes such as those encoding antibiotic resistance (multi-antibiotic resistant bacterial strains can be generated in this way).
  • As a result, when a genetic region is interrupted by integration of pBR322, the gene function is lost but new gene function (resistance to specific antibiotics) is gained.
  • Specifically, the transposon contains signals to truncate expression of an interrupted gene at the site of the insertion and then restart expression of a second truncated gene.

• Plasmids and Lysogeny

  • Both plasmids and lysogeny are used by bacteria and viruses to ensure transfer of genes and nucleic acids for viral reproduction.
  • Horizontal gene transfer is a major mechanism promoting bacterial antibiotic resistance, as the plasmid DNA can transfer genes from one species of bacteria to another.
  • The plasmid DNA which is transferred often has developed genes that encode for resistance against antibiotics.
  • The process of horizontal gene transfer can occur via three mechanisms: transformation, transduction and conjugation.
  • There are three mechanisms by which horizontal gene transfer can occur.