Worm Breeder's Gazette 10(2): 142

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.

Sequence Identity Between Caenorhabditis and Drosophila Transposable Elements

L.J. Harris, D.L. Baillie and A.M. Rose

Transposable elements, like Tc1, have a much wider phylogenetic 
distribution than previously thought.  Tc1 and TCb1 (also known as 
Barney) share sequence identity with the open reading frame (ORF) of 
the HB elements found in Drosophila melanogaster.  The ORFs of Tc1 and 
Barney can be aligned with HB1 after the introduction of 3 centrally 
located deletions in HB1.  These reading frames would code for 
proteins with 30% amino acid identity (42% when conservative changes 
are included).  Tc1, Barney and HB1 contain highly conserved blocks of 
amino acids which are likely to be in the functional domains of the 
putative transposase.  It is unfortunate that the HB elements in 
Drosophila are defective and can't reveal secrets of mobility.  Within 
the class of inverted repeat elements, a subclass of closely related 
elements exists.  This subclass includes Tc1 and Barney in the 
Nematoda and HB in Arthropoda.  Since these phyla are evolutionarily 
quite distant it is reasonable to suppose that Tc1-like elements will 
have a wide distribution within the eukaryotes.  Their presence in 
these two phyla could have resulted from the existence of the element 
in a common ancestor prior to the time of divergence (>500 million 
years) or might have resulted from more recent horizontal transfer.  
The sequence comparisons of Tc1, Barney and HB1 are to be published in 
Nucleic Acids Research.