We investigated intra-specific variation in the response of salmon to infection with the
myxozoan Ceratomyxa shasta by comparing the progress of parasite infection and measures of
host immune response in susceptible and resistant Chinook salmon Oncorhynchus tshawytscha at
days 12, 25 and 90 post exposure. There were no differences in...
The freshwater trematode Nanophyetus salmincola has been demonstrated to impair salmonid immune function and resistance to the marine pathogen Vibrio anguillarum, potentially resulting in ocean mortality. We examined whether infection by the parasite N. salmincola similarly increases mortality of juvenile Chinook Salmon Oncorhynchus tshawytscha when they are exposed to the...
Ceratonova gasterostea n. gen. n. sp. is described from the intestine of freshwater Gasterosteus aculeatus L. from the Klamath River, California. Myxospores are arcuate, 22.4 +/- 2.6 μm thick, 5.2 +/- 0.4 μm long, posterior angle 45 +/- 24°, with 2 sub-spherical polar capsules, diameter 2.3 +/- 0.2 μm, which...
Transmission dynamics of the actinospore stage of Ceratomyxa shasta to the salmonid host were investigated under field and laboratory conditions. The number of parasites transmitted and the transmission rate were compared between 2 different exposure durations and also among different water velocities, by means of field exposures. Under laboratory conditions,...
In mammals, CCR7 is the chemokine receptor for the CCL19 and CCL21 chemokines, molecules with a major role in the recruitment of lymphocytes to lymph nodes and Peyer´s patches in the intestinal mucosa, especially naïve T lymphocytes. In the current work, we have identified a CCR7 homologue in rainbow trout...
The recent identification of multiple genotypes of the salmonid parasite Ceratonova shasta with different virulence levels in Chinook salmon (Oncorhynchus tshawytscha) suggests that it may be possible to immunize fish against subsequent infection and disease. We hypothesized that exposure of Chinook salmon to the less virulent parasite genotype (II) prior...
Aseries of dams on the Deschutes River, Oregon, act as migration barriers that segregate the river system into upper
and lower basins. Proposed fish passage between basins would reunite populations of native potamodromous fish and
allow anadromous fish of Deschutes River origin access to the upper basin. We assessed the...
Severe infection by the endemic myxozoan parasite, Ceratonova (synonym, Ceratomyxa) shasta, has been associated with declines in and impaired recovery efforts of populations of fall-run Chinook Salmon Oncorhynchus tshawytscha in the Klamath River, California. The parasite has a complex life cycle involving a polychaete worm host as well as a...
Abstract: Myxobolus squamalis is a myxozoan skin parasite first reported from rainbow trout (Oncorhynchus mykiss). Identification of the parasite based on myxospore morphology is unreliable because M. squamalis is similar to several other myxobolids that share host species and geographic ranges. The only ssrRNA gene sequence available for M. squamalis...
Ceratomyxa shasta is a myxozoan parasite identified as a contributor to salmon mortality in the Klamath River, USA. The parasite has a complex life cycle involving a freshwater polychaete, Manayunkia speciosa and a salmonid. As part of ongoing research on how environmental parameters influence parasite establishment and replication, we designed...