ANALYSIS OF ROTIFER RIBOSOMAL GENE STRUCTURE USING THE POLYMERASE CHAIN-REACTION (PCR)

We have used the polymerase chain reaction (PCR) to selectively amplif y 18S ribosomal genes in rotifer taxa from major planktonic clades. In each case, we obtained an amplified product of between 1.8 and 2.0 ki lobase pairs. We analyzed the PCR products using 6- and 4-base cutting restriction enzymes, comparing fragment mobilities. For example, Brac hionus plicatilis (BSL strain) 18S genes have no restriction sites for Hind III or Bam HI and only a single site for Eco RI (all 6-base cutt ers). The 4-base cutter Msp I, on the other hand, has at least 4 enzym atic sites, producing fragments between approximately 110 and 460 base pairs in length. Results of this type can be used to differentiate am ong species and species groups within the Rotifera and can be used as the basis for construction of a broad molecular phylogeny of the group .