gene silencing

(noun)

Any technique or mechanism in which the expression of a gene is prevented.

Related Terms

Examples of gene silencing in the following topics:

  • Aquifex, Thermocrinis, and Related Bacteria

    • The presence of the insertion in the Thermotogae species may be due to a horizontal gene transfer.
    • In the 16S rRNA gene trees, the Aquificae species branch in the proximity of the phylum Thermotogae (another phylum comprising hyperthermophilic organisms) close to the archaeal-bacterial branch point.
    • However, a close relationship of the Aquificae to Thermotogae, and the deep branching of Aquificae, is not supported by phylogenetic studies based upon other gene/protein sequences and also by conserved signature indels in several highly-conserved universal proteins.
    • Comparison of the A. aeolicus genome to other organisms showed that around 16% of its genes originated from the Archaea domain.
    • A. aeolicus is also known as one of the few bacterial species capable of doing gene silencing.

  • Gene Families

    • Gene families are groups of functionally related genes arising from a duplicated gene.
    • A gene family is a set of several similar genes, formed by duplication of a single original gene, that generally have similar biochemical functions .
    • If the genes of a gene family encode proteins, the term protein family is often used in an analogous manner to gene family.
    • In contrast, gene complexes are simply tightly linked groups of genes, often created via gene duplication (sometimes called segmental duplication if the duplicates remain side-by-side).
    • Unequal crossing over generates gene families.

  • Tracking Cells with Light

    • In molecular biology, researchers use a reporter gene that they attach to a regulatory gene of interest.
    • Reporter genes ideally have distinguishable properties that can be easily detected and measured.
    • To introduce a reporter gene into an organism, scientists place the reporter gene and the gene of interest in the same DNA construct to be inserted into the cell or organism.
    • It is important to use a reporter gene that is not natively expressed in the cell or organism under study, since the expression of the reporter is being used as a marker for successful uptake of the gene of interest.
    • Reporter gene used as an indication of the regulatory sequence expression in the cell.

  • Reporter Fusions

    • A reporter fusion is the hybrid of a gene or portion of a gene with a tractable marker.
    • In molecular biology, a reporter gene (often simply reporter) is a gene that researchers attach to a regulatory sequence of another gene of interest in bacteria, cell culture, animals, or plants .
    • To introduce a reporter gene into an organism, scientists place the reporter gene and the gene of interest in the same DNA construct to be inserted into the cell or organism.
    • In these cases the reporter is directly attached to the gene of interest to create a gene fusion.
    • In molecular biology, a reporter gene (often simply reporter) is a gene that researchers attach to a regulatory sequence of another gene of interest in bacteria, cell culture, animals, or plants

  • Genetics and Regulation of N2 Fixation

    • These genes are found in nitrogen fixing bacteria and cyanobacteria.
    • The nif genes are genes encoding enzymes involved in the fixation of atmospheric nitrogen.
    • Nif genes have both positive and negative regulators.
    • Some of nif genes are: Nif A, D, L,K, F,H S,U,Y,W,Z .
    • The nif genes can be found on bacteria's chromosomes, but many times they are found on bacteria's plasmids with other genes related to nitrogen fixation, such as the genes needed for the bacteria to communicate with the plant host.

  • Gene Inversion

    • Gene Inversion utilizes recombinases to invert DNA sequences, resulting in an ON to OFF switch in the gene located within this switch.
    • There is also a change in orientation of the DNA that will affect gene expression or the structure of the gene product.
    • Through the utilization of specific recombinases, a particular DNA sequence is inverted, resulting in an ON to OFF switch, and vice versa, of the gene located within or next to this switch.
    • Many bacterial species can utilize inversion to change the expression of certain genes for the benefit of the bacterium during infection .
    • The inversion event can be simple by involving the toggle in expression of one gene, like E. coli pilin expression; or more complicated by involving multiple genes in the expression of multiple types of flagellin by S. typhimurium.

  • 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.
    • They can be harnessed as a genetic tool for analysis of gene and protein function.
    • 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.

  • RNA Regulation and Antisense RNA

    • Gene regulation, the ability to control whether a gene is expressed or not, is critical in controlling cellular and metabolic processes and contributes to diversity and variation in organisms.
    • Antisense RNAs are utilized for gene regulation and specifically target mRNA molecules that are used for protein synthesis.
    • The hok gene is a toxic gene and the sok gene is an antitoxin.
    • An example of a system found in nature that utilizes an antisense RNA to control gene regulation.
    • The hok gene is a toxic gene that can be translationally repressed by the production of an antisense mRNA, sok (anti toxic).

  • Complementation

    • It answers the question: "Does a wild-type copy of gene X rescue the function of the mutant allele that is believed to define gene X?".
    • If not, the two alleles must be defective in the same gene.
    • The beauty of this test is that the trait can serve as a read-out of gene function even without knowledge of what the gene is doing at a molecular level.
    • Thus, the test is used to decide if two independently derived recessive mutant phenotypes are caused by mutations in the same gene or in two different genes.
    • If both parent strains have mutations in the same gene, no normal versions of the gene are inherited by the offspring; they express the same mutant phenotype and complementation has failed to occur.

  • MHC Polymorphism and Antigen Binding

    • Chickens have among the smallest known MHC regions (19 genes).
    • The most intensely-studied HLA genes are the nine so-called classical MHC genes: HLA-A, HLA-B, HLA-C, HLA-DPA1, HLA-DPB1, HLA-DQA1, HLA-DQB1, HLA-DRA, and HLA-DRB1.
    • The A, B, C, E, F, and G genes belong to MHC class I, whereas the six D genes belong to class II.
    • MHC genes are expressed in co-dominant fashion.
    • In the Class-II locus, each person inherits a couple of genes HLA-DP (DPA1 and DPA2, which encode α and β chains), a couple of genes HLA-DQ (DQA1 and DQA2, for α and β chains), one gene HLA-DRα (DRA1) and one or two genes HLA-DRβ (DRB1 and DRB3, -4 o -5).