Download Facts about the Worm C. elegans

Facts about the Worm C. elegans:





First described as a species in 1900
Proposed as a model organism by Sydney Brenner in 1965
In the wild: lives in the soil and eats bacteria
Easy to culture in the lab on plates growing standard E. coli
Size: 1mm and transparent, so can only be seen with the microscope
o One of the smallest, simplest organisms with a nervous system
Figure 1
C. elegans worms as seen through an ordinary light
microscope
From:
http://www.kcchosting.co.uk/~pc/NewSite/the_genetics
_society



Lifespan:
o Egg (1 day)
o 4 Larval stages with molting after each one (3 days)
o Adult (Lives another 7 days)
2 sexes: self-fertilizing hermaphrodite and male
Physiology:
o Mouth and Digestive System
o Reproductive System
o Nervous System (but no brain)
o Cuticle (skin)
o Can sense chemicals (smell and taste), sense of touch, can detect heat but
not light or sound
Figure 2
C. elegans Anatomy
From:
http://universereview.ca/I10-82celegan.jpg


Genome:
o 6 different chromosomes (humans: 23)
o Genome size 100 million bases (humans: 3 billion)
o About 20 000 genes (humans: 30 000)
 About 6 000 C. elegans genes have human homologues
o Entire genome of C. elegans has been sequenced, and so has that of 4
other similar worms, with another 5-10 on the way
Laboratory Experiments
o Knock out one gene at a time to see what the effect is
o Insert Green Fluorescent Protein (GFP) into the genome to make parts of
the worm turn green
o Feed the worm with bacteria containing Interfering RNA, which will turn
off just one gene
o Destroy just one cell during embryogenesis and see what happens
Figure 3
C. elegans worm with all cells in the
nervous system expressing GFP
From:
http://www.biologie.ens.fr/bcsgnce/


Bioinformatics Experiments
o Compare C. elegans genome to that of other worms to look for regions of
sequence that are conserved (shared) and might be important
o Measure the gene expression of a specific cell or tissue and see which
genes are being used
Nobel Prizes have been awarded to 5 C. elegans researchers:
o 2002 Nobel Prize in Physiology or Medicine
 Sydney Brenner – pioneering genetic studies
 John Sulston – elucidating the exact cell lineage from one fertilized
egg to 959 cells in the adult
 Robert Horvitz – investigation of programmed cell death, which
later turned out to be very important in the development of cancer
o 2006 Nobel Prize in Physiology or Medicine
 Andrew Fire and Craig Mello– discovery of RNA interference
during translation