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Caenorhabditis elegans
February 11th, 2005
Princeton University
Karen Li
Image from http://ucdnema.ucdavis.edu/imagemap/nemmap/ENT156HTML/slides/fromWWW/cele/wbg5.1.jpg
Road map for today’s talk
1.
Model organisms: Uses? Advantages?
2.
Bioinformatics
•
WormBase
3.
Spectraplakins
4.
Caenorhabditis Elegans (“The Worm”)
5.
One scientist you should know: Sydney Brenner
6.
How to maintain your worm?
Model Organisms
Model systems
Advantages
Uses
Amphibians (Xenopus)
large eggs, easy to obtain and fertilize
eggs develop externally
fragment culture
embryology, induction
RNA and protein localization
morphogenesis
cell cycle
Drosophila
genetics, gene cloning
short generation time
axis formation
segmentation and cell identity
signalling pathways
Nematode
genetics
transparent embryo
small number of cells, invariant lineages
organelle movement
cell fate decisions
signal transduction
Zebrafish
transparent eggs
genetics
Mouse
mammal with relatively
short generation time
genetics
organogenesis
segmentation
cell determination
Chicken
embryos similar to mammals
easier to obtain and observe
embryo culture
organogenesis
cell death
ALSO: Sea urchins, ascidians, amphioxus, plants
Slide from Cellular and Developmental Biology lecture
RNA and protein localization
morphogenesis
cell determination
Heredity information in the egg cell determines the nature of the
whole multicellular organism.
Sea urchin
Mouse
Fucus seaweed
Heredity information determines how structures in the early stages
of the organism or a part of the organism develop. This process is
called morphogenesis.
Homologous organs (common ancestor) and Analogous organs
Effect of mutation in the kit gene: Both the baby and mouse are
heterozygous for the kit gene. This causes defective pigmentation
because pigment cells depend on the kit product as a receptor.
th
Bioinformatics
Bioinformatics: the systematic development and application of
computing systems and computational solution techniques to the
analysis of biological data obtained by experiments, modeling, database
search, and instrumentation
DATABASES
•NCBI (National Center for Biotechnology Information)—NCBI creates
public databases, conducts research in computational biology, develops
software tools for analyzing genome data, and disseminates biomedical
information - all for the better understanding of molecular processes
affecting human health and disease.
www.ncbi.org
•WormBase – rapidly evolving model organism database for the biology
and genomics of Caenorhabditis elegans and Caenorhabditis briggsae
www.wormbase.org
BLAST (Basic Local Alignment Search Tool)—search tool
designed to take protein and nucleic acid sequences and compare them
against a selection of NCBI databases. This gives information about
direct relationships that share isolated regions of similarity.
Tutorial: http://www.geospiza.com/outreach/BLAST/index.html
Spectraplakins!
Spectraplakins are large proteins that bind to all
three components of the cytoskeleton (actin, tubulin, and
intermediate filaments). They are required for mechanical
resilience of the epidermis.
In Drosophila, spectraplakins are
involved in crosslinking
cytoskeletal filaments, linking
the cytoskeleton to the plasma
membrane proteins, and acting
as a scaffold protein that recruits
signaling proteins to sites of
cytoskeletal activity
Figure from Journal of Cell
Science 115, 4215-4225 (2002)
Caenorhabditis elegans (Caeno, recent; rhabditis, rod; elegans, nice),
is a free-living, parasitic nematode that lives in soil, across most of
the temperate regions of the world, where it survives by feeding on
microbes such as bacteria.
Image from http://elegans.swmed.edu/Pictures/wild-type_low.gif
Video Links
Bird’s Eye view:
http://www.wormatlas.org/handbook/fig.s/BIRDSEYEMOVIE.qt
Worm crawling:
http://www.bio.unc.edu/faculty/goldstein/lab/crawl.mov
Professor Sydney Brenner
In 2002, the Nobel Assembly at
Karolinska Institutet awarded the Nobel
Prize in Physiology or Medicine jointly
to Sydney Brenner, Robert Horvitz and
John Sulston for their discoveries
concerning "genetic regulation of organ
development and programmed cell
death".
By using the nematode Caenorhabditis
elegans as a model system, the Laureates
identified key genes regulating these
processes. They
have also shown
that
corresponding
genes exist in
higher species,
including man.
http://nobelprize.org/medicine/educational/poster/2002/index.html; Brenner image from http://elegans.swmed.edu/Pictures/People/Brenner.gif
Life cycle of C. elegans: The life cycle is temperature-dependent.
C. elegans goes through a reproductive life cycle (egg to egg-laying
parent) in 5.5 days at 15°C, 3.5 days at 20°C, and 2.5 days at 25°C.
http://avery.rutgers.edu/WSSP/StudentScholars/project/introduction/worms.html
Dauer stage: when a worm encounters shortage of food, it enters
the developmental pathway to form the dauer larva that can survive
for months without food.
Male and Hermaphrodite Worms
Figure 1. Photomicrographs showing major anatomical features of the C. elegans
adult hermaphrodite (top) and male (bottom). Shown are lateral views under
bright-field illumination. Bar, 20 μm. (Reprinted, with permission, from
Sulston and Horvitz 1977.)
Hermaphrodite
Images from http://www.wormatlas.org/handbook/bodyshape.htm
Male
Image from http://www.wormatlas.org/handbook/bodyshape.htm
Inside the mouth of a male worm
Image from http://www.wormatlas.org/maleHandbook/GenIntroMalePartI.htm
Helpful links
Hypodermis:
http://www.wormatlas.org/handbook/hypodermis/hypodermis.htm
Mating:
http://www.wormatlas.org/maleHandbook/figsMale/WAmating.mov
Worm eating:
http://www.mcb.arizona.edu/wardlab/eatingvid.html
How to transfer your worms
Image from http://ucdnema.ucdavis.edu/imagemap/nemmap/ENT156HTML/slides/fromWWW/cele/wbg8.2.jpg
Intracellular Signaling Cascades in C. elegans Vulval Induction
http://nema.cap.ed.ac.uk/teaching/devbio3/NVD_lecture.html