Phylogeny and morphology of Glugea hertwigi from rainbow smelt Osmerus mordax found in Prince Edward Island, Canada

Abstract

Infection of rainbow smelt Osmerus mordax with the microsporidian Glugea hertwigi was diagnosed for the first time in Prince Edward Island, Canada. The prevalence of infection was 24%, 45 infected out of 187 examined fish captured in February and March 2009. Both large and small xenomas of G. hertwigi observed within the submucosa of the gastrointestinal tract and along the mesentery of the host contained only mature spores. Advanced and degraded xenomas associated with host reaction were described using light and transmission electron microscopy. The first rDNA sequence of G. hertwigi prepared in the present study completed the set of sequences of Glugea spp. available for comparison. The high level of rDNA sequence identity between Glugea spp. suggests that these may be variants of a single species.

Distribution, prevalence, and pathology of a microsporidian infecting freshwater sculpins

“…micro sporidia in the northern USA. Infection causes the formation of variable numbers and sizes of xenomas associated with tissues in the peritoneal cavity, consistent with Glugea infections reported from other fish species (Canning & Lom 1986, Lovy et al 2009). Phylogenetic analysis of Glugea sp.…”

“…infecting mottled sculpin most closely resemble descriptions of G. hertwigi from rainbow smelt in North America (Canning & Lom 1986, Lovy et al 2009). Xenomas ranged in size from barely visible to the naked eye to 1 cm in diameter and are associated with the body wall, fat body, gonads, and kidneys.…”

“…'SV' (HM626217) infecting Salvelinus fontinalis with 2% sequence divergence. In a similar manner to L. salmonae and H. sutherlandae, G. anomala, G. hertwigi, and G. stephani have been reported from multiple fish hosts (smelts and sticklebacks) from the northern USA and Canada, including areas that overlap the range of sculpins (Scott & Crossman 1973, Becker 1983, Lovy et al 2009). Overall, the variation in these Glugea rDNA sequences could indicate that these parasites represent local isolates of a single species, as has been suggested by multiple authors (Canning & Lom 1986, Pomport-Castillon et al 2000, Lovy et al 2009, Liu et al 2013).…”

Occurrence of microsporidians Glugea hertwigi and Pleistophora ladogensis, in smelt Osmerus eperlanus from two German rivers, North Sea coast

“…Later, this parasite was found infecting smelt O. mordax from North American freshwater systems (Schra der 1921) and Coregonus lavaretus and Hypomesus olidus from northern Russia (Ak merov 1946, Shulman & Shulman-Albova 1953). Ultrastructural observations of the mature spores of G. hertwigi from O. mordax showed the same difficulties we faced in the visualization of the spore structure, due to the spores having very electron-dense cytoplasm (Lovy et al 2009). Nevertheless, we were able to observe meronts, dividing meronts, sporoblast mother cells, and sporoblasts, which were not previously examined at the ultrastructural level for this species.…”

“…Recent advances in molecular characterization of microsporidians have revealed that G. hertwigi is closely related to G. ple coglossi, G. anomala, G. atherinae, and G. stephani -all species characterized by the production of xenomas (Lovy et al 2009). The close relationship of G. hertwigi and G. anomala could support the claim by Weissenberg (1968) concerning the successful transmission of G. hertwigi to a non-osmerid fish, Gasterosteus aculeatus, which is the type host of G. anomala (Weissenberg 1968, Lom 2002.…”