PARTIAL MITOCHONDRIAL-DNA SEQUENCE OF THE CRUSTACEAN DAPHNIA-PULEX

A 3667-base pair (bp) fragment of the mitochondrial genome of the crustacean Daphnia pulex has been sequenced and found to contain the complete genes for the small subunit ribosomal RNA, ND2, seven tRNAs and the control region. This organization is identical to that found in Drosophila yakuba mtDNA yet D. pulex mtDNA exhibits several unique features when compared to other mitochondrial sequences. The sequenced fragment is only 62.6% A + T which is much lower than that of any other arthropod mtDNA sequenced to date. D. pulex mtDNA also exhibits length conservation having shorter coding and non-coding regions. The putative control region is 689 bp in length and includes a sequence that has the potential to fold into a hairpin structure with a perfect 20-bp pair stem and a 22-base loop.