GREGG, C.S.*; NELSON, P.G.; TUCKER, M.C.; GRASSLE, J.P.: Development of a DNA Probe for the Identification of Early-Stage Mercenaria mercenaria (Hard Clam) Larvae

Early-stage bivalve larvae are extremely difficult to identify unequivocally using morphological methods because they lack diagnostic characteristics. As part of a study of larval transport of estuarine bivalves, an oligonucleotide probe was developed for identifying Mercenaria mercenaria larvae. The 18S rRNA gene from M. mercenaria was sequenced and compared with other bivalve species, including four species (from different genera) within the family Veneridae. A 25 base-pair region of the gene was identified that was unique to the genus Mercenaria. Subsequent tests using dot-blot hybridization revealed that the probe bound only to the Venerid species M. mercenaria, M. campechiensis, and Venerupis philippinarum. The method of using DNA probes with dot-blot hybridization for the identification of larvae should prove useful for small-scale studies where accurate identification of larvae is necessary.