caenorhabditis elegans quite a nifty li’l worm.. c. elegans is a small worm one millimeter long....
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Caenorhabditis elegans
Quite a nifty li’l worm.
C. elegans is a small worm one millimeter long. There are two sexes, a male and a self fertilizing hermaphrodite. Its inner workings are similar to a human’s, which is part of the reason its considered a model organism.
The Basics
Widely studied, C. elegans is a popular test subject among neurology researchers and has had many papers published on it in an array of of topics. Currently there are 342 papers listed under PubMed for C. elegans.
Who sequenced it? The Sanger Institute and Washington University.
When? While research on C. elegans began 1968 by Sydney Brenner, its genome wasn’t published until 1998 and not fully complete until 2002.
Why? Research began on C. elegans because of interest its nervous and developmental systems, as they are very similar to humans. It is still being used in research for these same reasons.
Because C. elegans is a eukaryote it contains a nucleus. Within that nucleus are 6 chromosomes that contain a total of 100,000,000 base pairs with roughly 19,800 genes.
A related organism, C. briggsae, is in the process of being sequenced. These two are often compared to each other for reference.
Ribonucleic acid (RNA)Ribonucleic acid (RNA)
RNA vs. DNA
RNA-world hypothesis
-messenger RNA (mRNA)
-transfer RNA (tRNA)
-ribosomal RNA (rRNA)
-catalytic RNA (ribozymes)
-small interfering RNA (siRNA)
-ncRNAs (miRNA, tncRNA,piRNA...)
RNA speciesRNA species
www.contexo.info/DNA_Basics/Protein_synthesis.htm
rRNA
Gene silencing by dsRNAGene silencing by dsRNA
control progeny of injected worm
unc-22 dsRNA
RNA interference (RNAi)RNA interference (RNAi)
• The Nobel Prize in Physiology or Medizine 2006 for Craig Mello and Andrew Fire for their discovery of RNAi in C.elegans
nobelprize.org
RNAi mechanism in C.elegans: basic scheme
RNAi mechanism in C.elegans: basic scheme
less mRNA, less protein = gene silencing
RNAiRNAi
• conserved mechanism (at least 1 000 000 000 (=thousand billion) years old)
• roles– primitive immune system
– gene regulatory mechanism (via mRNA destruction)
– chromatin remodelling (via histone modifications)
– DNA elimination (in Tetrahymena thermophila)
• tool– functional genomics
– potential for pharmaceuticals