Generation of Transgenic C. elegans by Biolistic Transformation

Summary

Transgenic worms are commonly used in C. elegans research. Described is a simple, yet effective, protocol to introduce transgenes into worms using biolistic bombardment with DNA-coated gold particles. The effort involved and results of bombardment compare favorably with microinjection for the generation of transgenic animals.

Abstract

The number of laboratories using the free living nematode C. elegans is rapidly growing. The popularity of this biological model is attributed to a rapid generation time and short life span, easy and inexpensive maintenance, fully sequenced genome, and array of RNAi resources and mutant animals. Additionally, analysis of the C. elegans genome revealed a great similarity between worms and higher vertebrates, which suggests that research in worms could be an important adjunct to studies performed in whole mice or cultured cells. A powerful and important part of worm research is the ability to use transgenic animals to study gene localization and function. Transgenic animals can be created either via microinjection of the worm germline or through the use of biolistic bombardment. Bombardment is a newer technique and is less familiar to a number of labs. Here we describe a simple protocol to generate transgenic worms by biolistic bombardment with gold particles using the Bio-Rad PDS-1000 system. Compared with DNA microinjection into hermaphrodite germline, this protocol has the advantage of not requiring special skills from the operator with regards to identifying worm anatomy or performing microinjection. Further multiple transgenic lines are usually obtained from a single bombardment. Also in contrast to microinjection, biolistic bombardment produces transgenic animals with both extrachromosomal arrays and integrated transgenes. The ability to obtain integrated transgenic lines can avoid the use of mutagenic protocols to integrate foreign DNA. In conclusion, biolistic bombardment can be an attractive method for the generation of transgenic animals, especially for investigators not interested in investing the time and effort needed to become skilled at microinjection.

Protocol

Overview

Traditionally transgenic worms were generated by microinjecting transgene DNA into the C. elegans germline ^1,2,3,4. While successful, this approach required specialized equipment and the development of experience with worm anatomy and the microinjection technique. More recently biolistic bombardment has been developed as an alternate approach which uses DNA-coated gold particles to introduce foreign DNA into the germline ^5,6. This approach requires less time investment in terms of practice to become successful.

The biolistic bombardment of C. elegans to generate tr....

Discussion

Biolistic bombardment is a simple method to introduce foreign DNA into many organisms, including C. elegans ^1,5,6,7,16. It relies upon gold particles forming a complex with DNA in the presence of CaCl₂. Cationic polyamines, such as spermidine, protect DNA from nuclease degradation in vivo. Since spermidine is a labile molecule, it is important to store it in small aliquots at -20°C, and make the solution right before performing the bombardment. As we described in the bombardment protoco.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Gold particles	Inbio gold	BD021	1micron
Midiprep kit	Qiagen	12143
Spermidine	Sigma-Aldrich	S4139
Protamine	Sigma-Aldrich	P4505
Macrocarriers	Bio-Rad	165-2335
PDS-1000/He Hepta System	Bio-Rad	165-2257
Rupture disk	Bio-Rad	165-2330
Nystatin	Sigma-Aldrich	N1638
Streptomycin	MP Biomedicals	100556