An assessment of lesions in bay scallops Argopecten irradians attributed to Perkinsus karlssoni (Protozoa, Apicomplexa)

Abstract

ABSTRACT-Leslons found in bay scallops Argopecten ~r r a d imore than 1 organism associated with this name which ans imported into Atlantic Canada for culture were attributed may later be described outside the genus Perkinsus, to a parasite Perklnsus karlssonj It appears, however, that Bay scallops Argopecten irradians imported into stages froin several organisms were combined to create the life cvcle of P karlsson~. (McGladdery et al. 1991, McGladdery et al. 1993). There are significant differences, however, between P. karlssoni and the other 3 described species of Perkinsus. P. karlssoni is used hereafter as a matter of convenience with the recognition that there may be 'Present address CSIRO Divls~on of Fishenes, GPO Box 1538, Hobart, Tasmania 7001, Australia E-mall louise goggin@ml csiro au Perkinsus. P. karlssoni which were healthy when preserved have not been seen under the electron microscope. The organisms identified as P. karlssoni in electron micrographs published by Whyte et al. (1994) (Fig. 18a, b) are dead organisms encapsulated by ceroid and do not resemble Perkinsus.In histological sections, the meront of species of Perkinsus is distinguished by a large eccentric vacuole which sometimes contains a vacuoplast. A vacuole was rarely observed in P. karlssoni, but a dense basophilic body was found next to the nucleus which could b e equivalent to the vacuoplast of P. marinus (McGladdery et al. 1991). The basophilic body of P. karlssoni, however, was not contained in a large eccentric vacuole, which makes this association unlikely. Furthermore, the presence of a basophilic body does not diagnose a Perkinsus spp. because the vacuoplast can be either basophilic or eosinophilic in P. marinus (Mackin et al. 1950) or slightly eosinophilic (when present) in P. olseni (Lester & Davis 1981).Perkinsus karlssoni differs from described species of Perkinsus in other ways. P. karlssoni was not recognised by an antibody raised against the meront of P. O Inter-Research 1996 Resale of full a r t~c l e not p e r m~t t e d

Occurrence of Perkinsus olseni (Protozoa: Apicomplexa) and other parasites in the venerid commercial clam Pitar rostrata from Uruguay, southwestern Atlantic coast

“…P. karlssoni is no longer considered to be a valid species. Thus, the identity of the pathogen that caused the disease in Argopecten irradians in Atlantic Canada and eastern USA remains unknown (Goggin et al 1996). The possibility of synonymy between P. chesapeaki and P. andrewsi (Dungan et al 2002) and between P. olseni and P. atlanticus based in the homology found in the nontranscribed regions of the rRNA cluster has also been postulated (Goggin 1994, Murrell et al 2002.…”

Perkinsosis in molluscs: A review

“…A subsequent study on this parasite, however, concluded that it was not a valid Perkinsus species (Goggin et al 1996).…”

Immune parameters in carpet shell clams naturally infected with

“…The pathogen has been associated with host lesions (Goggin et al, 1996), loss in weight (Ray, 1954), changes in physiological processes (Paynter, 1996), and even mass mortalities (Burreson & Ragone Calvo, 1996). In Galicia, several clam mortalities have occurred since 1989-90, Perkinsus being associated with them (Figueras et al, 1992).…”