Characterization of a species-specific satellite DNA from the entomopathogenic nematode Steinernema carpocapsae

An HaeIII satellite DNA family has been cloned from the entomopathogenic nematode Steinernema carpocapsae. This repeated sequence appears to be an unusually abundant satellite DNA, since it constitutes about 62% of the S. carpocapsae genome. The nucleotide sequences of 13 monomers have been determined. This satellite DNA family is represented by two sub-families: one with monomeric units of 170 bp and the other with monomeric units of 182 bp. These monomers are quite homogeneous in sequence, showing an average intermonomer variability of 6% from the consensus sequence. These results suggest that some homogenizing mechanism is acting to maintain the homogeneity of this satellite DNA. After hybridization with the genomic DNA of several other Steinernema species, this DNA sequence appears to be specific to the S. carpocapsae genome. Therefore, the species specificity and the high copy number of the HaeIII satellite DNA sequence should provide a rapid and powerful tool which could contribute to the identification of Steinernema species.