Meeting Abstract
We describe a microsporidian parasite that we recently discovered within the oocytes of wild-caught Maculaura alaskensis in Coos Bay, Oregon. M. alaskensis is a pilidiophoran heteronemertean common to sandy mudflats of Washington and Oregon, which has been the basis for several previous developmental studies; microsporidians are closely related to fungi and live as obligate intracellular parasites of animals and protists. We find the parasite in both dissected oocytes and spontaneous laboratory spawnings of M. alaskensis, most commonly near the end of their normal reproductive season. Some fraction of oocytes released from infected females contain one to several parasitophorous vesicles, visible by transmitted light microscopy, containing dozens to hundreds of apparent spores. Each mature spore contains two nuclei and a polar tube, traits distinctive for microsporidia. Some infected oocytes develop a chorion-like investment, a feature not typically observed in healthy oocytes of M. alaskensis. In the laboratory, spore-bearing oocytes can be fertilized with varying success, and occasionally yield overtly-infected pilidium larvae. Our present goals are to develop methods to allow us to determine which microsporidian life stages are present in oocytes, larvae, and adult tissues, and thereby characterize the parasite’s life cycle, discover its mode of transmission, and assess its influence on host reproduction and development.
