Worm Breeder's Gazette 10(1): 52

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Different Tc1 Elements from the C. elegans Strain Bergerac

R.H.A. Plasterk

Figure 1

The Tc1 transposable element of C.  elegans has been sequenced (
Rozenzweig and Hirsch, NAR 11, 4201).  It is 1610bp long and contains 
one major ORF, encoding a 273 amino acid protein.  All C.  elegans 
strains contain copies of Tc1, though not all strains are active in 
transposition (e.g. the strain Bristol is inactive).  The Bergerac 
strain shows active transposition of Tc1, and contains approximately 
300 copies of Tc1 that seem to have (almost) all the same restriction 
pattern (Liao et al., PNAS 80, 3585).  We are interested in the major 
ORF that -we think- may encode the transposase (TcA) of the element.  
I sequenced the TcA gene of an element that had inserted into the 
unc22 gene of the Bergerac strain (st137, kindly provided by Dr. D.  
Moerman).  As shown below there are a few differences in the coding 
sequence.  One of them is an amber triplet in this copy of the TcA 
gene, that results in a much shorter version of the gene.  It has been 
suggested by several authors that the Tc1 activating gene in Bergerac 
may itself be a copy of Tc1.  Possibly the difference between trans-
active and inactive elements is not (like in the maize Ac/Ds system) 
in the size of the elements but in the primary sequence of the TcA.
[See Figure 1]

Figure 1