Summary: C. elegans is an ideal organism for studying a myriad of questions in cell biology. In particular, its genetic maliablity and optical transparency make the analysis of cellular and subcellular phenomenon, in both live and fixed tissue, quite straightforward.

Fixed versus live Specimens

Antibody-tubulinG
Click on the image to view bigger image
(640 KB).
GFP-tubulinG
Click on the image to view the movie
(live specimen enables time-lapse imaging,
2 MB, 12")
A confocal microscopy image with fixed specimen. This is a C. elegans embryoG with tubulinG labeled in green.
A MPFE microscopy image with live specimen. This is a C. elegans embryoG with GFP fused with tubulinG.

Fixed:

The specimen is no longer alive and the tissue/cell structure has been preserved (usually chemically with formaldehyde or alcohols).

  • Advantages: the tissue can be stained to accentuate specific structures, the tissue is static. Specimens can be prepared in large numbers. The specimen can be re-analyzed at a later time.
  • Disadvantages: fixations can alter the tissue. You cannot see dynamic changes within the specimen.
  • Examples: 1) antibody-specific labeling, 2) ultra-structure G analysis (e.g.: EM)

Live:

  • Advantages: dynamic changes within the specimen can be seen. It is likely to provide a truer representation of the phenomenon of interest.
  • Disadvantages: often can only visualize one specimen at a time (thus is more time consuming). The specimen can only be used once.
  • Examples: 1) GFP, 2) time-lapse (e.g.: DIC)

Commonly used cell biology techniques

Commonly used Microscopy

Light Microscopy

A C. elegans EmbryoG at pro-nuclei meetingG stage (before dividing into 2-cell embryo)

Electron Microscopy (EM)


(Flash movie, 460K, movie length: 27")

TEM specimenG is a C. elegans embryoG (cross-sectioned).
SEM specimen is a bunch of C. elegans (surface imaging).

Microscopy Bioclips

This bioclipG illustrates commonly used microscopy in C. elegans research. It does not focus on the technical aspects of microscopes but rather emphasizes how each type of microscopy helps researchers observe biology events. Microscopies addressed are DIC, confocal, multiphoton, TEM and SEM. Computational processing, such as color mapping, used in current microscopy is also illustrated.


(A flash movie, 50 MB, movie length: 19' 44")

Glossary:

Bioclip: a self-contained animations with in-depth presentation of biology concepts to help convey the research focus of a laboratory.

Embryo: the early developmental stage of an organism (C. elegans in this case) after fertilization and before hatching.

Pharmacological treatments: the applications of subtances, such as drugs, that cause specific effects on celluar processes.

Pro-nuclei meeting: the developmental stage where pro-nuclei that are migrating from opposite ends (paternal and maternal pro-nuclei) of the fertilized zygote meet.

Protein: a linear polymer of amino acids linked together in a specific sequence and usually containing more than 50 residues. Proteins form the key structural elements in cells and participate in nearly all cellular activities.

Specimen: any animal or plant, or any part, product, egg, seed or root of any animal or plant. For example, C. elegans embryos can be specimens that one can look at with light microscopy.

Tubulin: a family of globular cytoskeletal proteins that polymerize to form microtubules.

Ultra structure: ultrastructure is the arrangement of the smallest elements making up a specimen. These include structures that are below the resolution of light.