Conservation of a satellite DNA sequence (SATB) in the tilapiine and haplochromine genome (Pisces: Cichlidae).
We have cloned and sequenced a 1900-bp EcoRI fragment (SATB) from the tilapiine fish Oreochromis niloticus. The SATB sequence is highly reiterated in the tilapiine genome and organized in long tandem arrays. A 760-bp HindIII fragment, an internal component of SATB, has also been cloned and sequenced from the related tilapiine species Oreochromis hornorum. Hybridization of the radiolabelled 760-bp HindIII repeat detected the presence of the SATB repeat in the genomes of several tilapiine species as well as the haplochromine species Haplochromis (Protomelas) similis. The 760-bp HindIII fragment did not hybridize to genomic DNA of Etroplus maculatus (an Asian cichlid) or to that of Cichlasoma meeki (a South American cichlid). The SATB repeat sequence is 56% AT and constitutes 0.2-5% of the tilapiine genome depending on the species examined. Four imperfect 21-bp direct repeat sequences are present within the cloned 1900-bp EcoRI repeat. Alignment of the four direct repeats from the O. niloticus cloned 1900-bp DNA and the two homologous direct repeats from the O. hornorum 760-bp HindIII repeat revealed a core motif of 11 bp that exhibits 100% sequence identity between all of the direct repeats. The conservation of this motif in the SATB repeat suggests that this sequence may be under selective constraint.
Franck
J P
JP
Department of Biology, Dalhousie University, Halifax, N.S., Canada.
Wright
J M
JM
D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004276:DNA, Satellite / Q000235:genetics*; D008969:Molecular Sequence Data; D010471:Perches / Q000145:classification / Q000235:genetics*; D010802:Phylogeny; D012091:Repetitive Sequences, Nucleic Acid; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
D004276:DNA, Satellite