Repeated Sequences Flank the Tubulin Genes of Artemia

Abstract

We have isolated separate genomic DNA clones containing one α- and two β- tubulin genes of the brine shrimp, Artemia, which we will refer to here as α2, β3 and β7. We have mapped the coding region of each isolate, and we have discovered that the non-coding regions of these isolates contain at least three different kinds of repeated DNA sequence elements. (1) All three isolates contain sequence elements repeated several hundredfold and scattered throughout the Artemia genome (LINES and/or SINES). There is no homology between the elements flanking the α-tubulin gene and those within 2kb of the α-tubulin genes. (2) At least one repeated sequence element in α2 is also present in β7 at a distance of more than 2kb from the tubulin coding region. (3) An inverted repeat element, detected as a “snap-back” structure by S1 nuclease treatment, is adjacent to the coding region in β7. This sequence element is about 2kb in length and is not present in either α2 or β3. Direct DNA sequencing of these repeated elements is in progress.