Worm Breeder's Gazette 11(4): 57

These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.

Transformation of C. briggsae

Eric Aamodt, May Chung and Jim McGhee

To identify the control regions of the C.  elegans gut-specific 
esterase gene (ges-1), we are using a variety of approaches including 
a comparison of the upstream control regions of ges-1 and the 
homologous esterase gene from C.  briggsae (cloned and sequenced from 
the Baillie library by Brian Kennedy and Fran Allen).  For this 
approach to be valid, we needed to show that the esterase gene from 
one species is properly expressed in the other species.  It was easy 
to show that the C.  briggsae esterase is expressed in the gut of C.  
elegans by transforming the C.  briggsae gene into a ges-1(0) strain 
of C.  elegans and then staining the transformants for esterase.  We 
did this experiment using both transient transformation and 
extrachromosomal heritable transformation.  To show that the C.  
elegans properly expressed in C.  briggsae, 
we needed to make a strain of C.  briggsae that was transformed with 
the C.  elegans  tried the rol-6 dominant 
mutant gene and followed the transformation procedure of Mello et al.  
(WBG 11-1:18 and WBG 11-3:12).  Roller strains of C.  briggsae were 
easily obtained (the rachis of C.  briggsae is even easier to hit than 
that of C.  elegans).  When the ges-1 gene was used in a 
cotransformation with the rol-6 gene all of the esterase expression 
was confined to the guts of the transformants i.e.  the transformants 
looked exactly like wildtype C.  briggsae.  We then used isoelectric 
focusing gels on extracts of the transformed C.  briggsae followed by 
staining of the gel for esterase activity to show that the C.  elegans 
indeed being expressed.  Thus, the C.  
elegans expressed in C.  briggsae and it is 
expressed only in the gut.  A deleted construct of ges-1 that contains 
only 521 base pairs 5' from the translation initiation codon is 
expressed in the pharynx muscles of C.  elegans (E.  Aamodt, M.  Chung 
and J.  McGhee, manuscript submitted).  When this deleted ges-1 gene 
was transformed into C.  briggsae, the transformants also express the 
esterase gene in their pharynx.  In other words, not only is the 
intact gene properly expressed but the ectopic expression of the 
deleted ges-1 is identical between the two species.  Thus, both ges-1 
and the mutant rol-6 genes are properly expressed in C.  briggsae.  
Cotransformation of C.  briggsae using the rol-6 marker gene should be 
useful to others who wish to see if their favorite C.  elegans gene 
works in C.  briggsae.