The vertebrate 7S K RNA separates hagfish (Myxine glutinosa) and lamprey (Lampetra fluviatilis).
7S RNA sequences from the hagfish (Myxiniformes) and lamprey (Petromyzontiformes) were cloned and analyzed. In both species, 7S L RNA (also designated SRP RNA, since it represents the RNA constituent of the signal recognition particle) was clearly detectable. The sequence similarity between the two species was 86%, compared with about 75% similarity between either of these species and mammals. 7S K RNA was also cloned from the lamprey. The similarity between the 7S K RNA of the lamprey and that of mammals was 68%. Interestingly, several interspersed elements were found with nearly 100% similarity compared with mammals. In contrast to the lamprey, no 7S K RNA-related sequences were detectable among hagfish RNA, neither in northern blots nor with the PCR assay. In view of the significant conservation between the 7S K RNA of lamprey and that of mammals (human), this unexpected result clearly separates lamprey and hagfish. In addition, the lack of detectable 7S K RNA sequences in an outgroup, such as amphioxus, indicates that these results do not reflect an autapomorphy of hagfish. Therefore, our data provide additional support to the notion of a sister group relationship between Petromyzontiformes and gnathostomous vertebrates to the exclusion of Myxiniformes.
Gürsoy
H C
HC
Department of Biochemistry, Faculty of Chemistry, Ruhr-University, D-44780 Bochum, Germany.
Koper
D
D
Benecke
B J
BJ
D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary; D006196:Hagfishes / Q000235:genetics*; D006801:Humans; D007798:Lampreys / Q000235:genetics*; D008969:Molecular Sequence Data; D012313:RNA / Q000235:genetics*; D012342:RNA, Small Nuclear / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
D018076:DNA, Complementary; D012342:RNA, Small Nuclear; D012313:RNA