Organization and molecular cytogenetics of a satellite DNA family fromHoplias malabaricus (Pisces, Erythrinidae)

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Abstract
The chromosomes of the primitive South American teleost fishHoplias malabaricus have been analyzed by classical cytogenetic (C-, AgNOR-, Hoechst 33258-, and Q-banding) techniques. A highly repetitive DNA family has been cloned and sequenced. It is a tandemly repeated sequence of about 355 bp, yielding an overall base pair composition of 67% AT with long runs of >50% As and 70% Ts. Analysis of sequence variation has allowed the further categorization ofHoplias satellite DNA into two evolutionarily related subfamilies A and B, distinguishable by characteristic insertions and deletions within this 355-bp monomer. Subfamily A satellite is found (in diverged form) at the centromeres of mostH. malabaricus chromosomes. Sequence variants are clustered on specific chromosomal subsets. Subfamily B satellite is highly specific for the paracentromeric heterochromatin on one particular chromosome pair by fluorescencein situ hybridization. These results indicate that theHoplias satellite DNA family has evolved in a concerted manner predominantly via recombination events involving homologous, rather than non-homologous chromosome regions. The clones isolated here may be useful for the molecular, genetic, and cytological analysis of the genusHoplias.