Team:Queens Canada/Project/Intro
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- | < | + | <h3red> <i>Caenorhabditis elegans:</i> A Model Organism</b> </h3red><p> |
<regulartext><i>C. elegans </i> has been a long standing model organism for multicellular eukaryotes due to its simplistic structure and features which, despite being base in nature, provide highly analogous representations of biological processes in other model organisms. Generally, model organisms must have a set of common traits which allow for ease of use and observation such as rapid maturation and small growth cycles, small size, availability, and tractability. <i>C. elegans</i> is a particularly attractive model organism not only for its adherence to the above criteria but due to several other factors as well. </regulartext> <p> | <regulartext><i>C. elegans </i> has been a long standing model organism for multicellular eukaryotes due to its simplistic structure and features which, despite being base in nature, provide highly analogous representations of biological processes in other model organisms. Generally, model organisms must have a set of common traits which allow for ease of use and observation such as rapid maturation and small growth cycles, small size, availability, and tractability. <i>C. elegans</i> is a particularly attractive model organism not only for its adherence to the above criteria but due to several other factors as well. </regulartext> <p> | ||
- | <regulartext> <i>C. elegans</i> is a transparent, nonparasitic nematode approximately 1mm in length and is found in most temperate soil climates. It is easily sustained in the lab through use of agar plates or liquid cultures at laboratory temperatures. It can feed solely on <i>E. coli</i>, and is hence cheaply cultivated. Its transparency allows for the study of cellular differentiation and tissue mapping via fluorescing proteins. The rapidity with which <i>C.elegans</i>reproduces and the large number of offspring generated per hermaphrodite leads to the production of high numbers of offspring in a short amount of time. </regulartext> <p> | + | <regulartext> <i>C. elegans</i> is a transparent, nonparasitic nematode approximately 1mm in length and is found in most temperate soil climates. It is easily sustained in the lab through use of agar plates or liquid cultures at laboratory temperatures. It can feed solely on <i>E. coli</i>, and is hence cheaply cultivated. Its transparency allows for the study of cellular differentiation and tissue mapping via fluorescing proteins. The rapidity with which <i>C.elegans</i> reproduces and the large number of offspring generated per hermaphrodite leads to the production of high numbers of offspring in a short amount of time. </regulartext> <p> |
<regulartext>A population of <i>C. elegans </i> is comprised of two sexes: hermaphrodites and males, the former being predominant in any given population. Because of a lack of male-hermaphroditic mating, the genotypes of worms produced in culture remain generally homogenous. While the life span of a worm can be anywhere from 2-3 weeks in length, the worms themselves reach maturation within 3 days. At this point, all expression patterns in their cells are considered adult and the number of somatic cells within the worm remains at a constant of 959 for hermaphrodites and 1031 for males. The expected results of genetic construct microinjection can be detected and tested at this point. </regulartext> <p> | <regulartext>A population of <i>C. elegans </i> is comprised of two sexes: hermaphrodites and males, the former being predominant in any given population. Because of a lack of male-hermaphroditic mating, the genotypes of worms produced in culture remain generally homogenous. While the life span of a worm can be anywhere from 2-3 weeks in length, the worms themselves reach maturation within 3 days. At this point, all expression patterns in their cells are considered adult and the number of somatic cells within the worm remains at a constant of 959 for hermaphrodites and 1031 for males. The expected results of genetic construct microinjection can be detected and tested at this point. </regulartext> <p> | ||
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<regulartext>G-protein Coupled receptors are seven-transmembrane domain receptors (also known as serpentine, 7TM, or G-protein-linked receptors) that bind ligands extracellularly, resulting in the activation of a signal transduction pathway within the cell upon ligand binding. They are sensory receptors which may bind lipids, peptides, light sensitive molecules, odour molecules, pheromones, hormones, ions, or neurotransmitters. GPCRs exist only in eukaryotic organisms where they affect many physiological processes including the visual and olefactory senses, behavioural and immune system regulation, autonomic nervous system transmission, and cell density sensing. </regulartext><p> | <regulartext>G-protein Coupled receptors are seven-transmembrane domain receptors (also known as serpentine, 7TM, or G-protein-linked receptors) that bind ligands extracellularly, resulting in the activation of a signal transduction pathway within the cell upon ligand binding. They are sensory receptors which may bind lipids, peptides, light sensitive molecules, odour molecules, pheromones, hormones, ions, or neurotransmitters. GPCRs exist only in eukaryotic organisms where they affect many physiological processes including the visual and olefactory senses, behavioural and immune system regulation, autonomic nervous system transmission, and cell density sensing. </regulartext><p> | ||
- | <regulartext>These receptors are integral membrane proteins with helical domains that span through the cell membrane. While the extracellular domain is available to bind an agonist or antagonist (ligand), the intracellular domain is coupled to a Guanine Nucleotide Binding Protein (G-Protein). The G-protein acts as a molecular switch, where the binding of GTP (guanosine triphosphate) represents the switch being “on” and the binding of GDP represents the switch being “off”. | + | <regulartext>These receptors are integral membrane proteins with helical domains that span through the cell membrane. While the extracellular domain is available to bind an agonist or antagonist (ligand), the intracellular domain is coupled to a Guanine Nucleotide Binding Protein (G-Protein). The G-protein acts as a molecular switch, where the binding of GTP (guanosine triphosphate) represents the switch being “on” and the binding of GDP represents the switch being “off”.</regulartext><p> |
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+ | <regulartext>The consequences of the switch being “on” or “off” relates to what occurs within the cell. The family of G-proteins which bind to GPCRs are termed Heterotrimeric G-proteins and are comprised of alpha, beta, and gamma subunits. In response to a conformational change in the GPCR, which results after a ligand binds to the GPCR, the G-protein exchanges a GDP for a GTP and then dissociates from the cell membrane to initiate a signal cascade within the cell, resulting in a biological response.</regulartext><p> | ||
<regulartext>A GPCR is activated when a ligand binds to its extracellular domain. This activation induces a conformational change in the receptor and allows it to act as a guanine nucleotide exchange factor (GEF) which trades GDP for GTP on the Gα subunit of the G-protein. The Gα subunit may then dissociate from the Gβγ dimer, which anchors the G-protein to the membrane, and the GPCR to affect intracellular signalling proteins or target functional proteins directly depending on the α subunit type. Once dissociated, a new Gα subunit with bound GTP binds to the Gβγ subunit, and hence, signalling via GPCR may continue. The process is seen in the figure below.</regulartext> | <regulartext>A GPCR is activated when a ligand binds to its extracellular domain. This activation induces a conformational change in the receptor and allows it to act as a guanine nucleotide exchange factor (GEF) which trades GDP for GTP on the Gα subunit of the G-protein. The Gα subunit may then dissociate from the Gβγ dimer, which anchors the G-protein to the membrane, and the GPCR to affect intracellular signalling proteins or target functional proteins directly depending on the α subunit type. Once dissociated, a new Gα subunit with bound GTP binds to the Gβγ subunit, and hence, signalling via GPCR may continue. The process is seen in the figure below.</regulartext> | ||
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<regulartext>A table can be seen below which lists the GPCRs present in <i>C.elegans</i> the neurons in which they are expressed. It also shows the function of the GPCR and method of signal transduction.</regulartext><p> | <regulartext>A table can be seen below which lists the GPCRs present in <i>C.elegans</i> the neurons in which they are expressed. It also shows the function of the GPCR and method of signal transduction.</regulartext><p> | ||
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+ | <img align="left" style="margin-bottom:0px; width: 755px; padding:0;" src="https://static.igem.org/mediawiki/2011/6/66/Queens_CanadaTable.png"> | ||
<regulartext>QGEM 2011 focused on utilizing the chemosensory system of <i>C.elegans</i> by expressing non-native GPCRs in neurons where a forward chemotactic response was the ultimate downstream effect of ligand binding.</regulartext> | <regulartext>QGEM 2011 focused on utilizing the chemosensory system of <i>C.elegans</i> by expressing non-native GPCRs in neurons where a forward chemotactic response was the ultimate downstream effect of ligand binding.</regulartext> |
Latest revision as of 03:54, 29 October 2011