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morphological and molecular confirmation of myxobolus cerebralis myxospores infecting wild‑caught and cultured trout in north carolina (se usa).we used microscopy and molecular biology to provide the first documentation of infections of myxobolus cerebralis (myxozoa: myxobolidae), the etiological agent of whirling disease, in trout (salmonidae) from north carolina (usa) river basins. a total of 1085 rainbow trout oncorhynchus mykiss, 696 brown trout salmo trutta, and 319 brook trout salvelinus fontinalis from 43 localities across 9 river basins were screened. myxospores were observed microscopically in pepsin-trypsin digested heads of r ...201729160217
the impact of tetracapsuloides bryosalmonae and myxobolus cerebralis co-infections on pathology in rainbow trout.myxozoan parasites pose emerging health issues for wild and farmed salmonid fish. rainbow trout (oncorhynchus mykiss) is a particularly susceptible species to tetracapsuloides bryosalmonae (malacosporea), the etiological agent of proliferative kidney disease (pkd), and to myxobolus cerebralis (myxosporea), the etiological agent of whirling disease (wd). the objective of this study was to investigate the impact of myxozoan co-infections on the pathogenesis of pkd and wd in the rainbow trout.201728946913
a rnai-based therapeutic proof of concept targets salmonid whirling disease in vivo.myxobolus cerebralis is a cnidarian-myxozoan parasite that causes salmonid whirling disease. m. cerebralis alternates between two hosts: (1) a vertebrate salmonid and (2) an invertebrate oligochaete, tubifex tubifex. there is no successful treatment for salmonid whirling disease. myxsp-1 is a m. cerebralis serine protease implicated in whirling disease pathogenesis. we hypothesized that short-interfering rna (sirna)-induced rna interference (rnai) can silence myxsp-1 in the invertebrate host and ...201728575083
accelerated deactivation of myxobolus cerebralis myxospores by susceptible and non-susceptible tubifex tubifex.in the 1990s, the tubifex tubifex aquatic oligochaete species complex was parsed into 6 separate lineages differing in susceptibility to myxobolus cerebralis, the myxozoan parasite that can cause whirling disease (wd). lineage iii t. tubifex oligochaetes are highly susceptible to m. cerebralis infection. lineage i, iv, v and vi oligochaetes are highly resistant or refractory to infection and may function as biological filters by deactivating m. cerebralis myxospores. we designed a 2-phased labor ...201627596858
genomic insights into the evolutionary origin of myxozoa within cnidaria.the myxozoa comprise over 2,000 species of microscopic obligate parasites that use both invertebrate and vertebrate hosts as part of their life cycle. although the evolutionary origin of myxozoans has been elusive, a close relationship with cnidarians, a group that includes corals, sea anemones, jellyfish, and hydroids, is supported by some phylogenetic studies and the observation that the distinctive myxozoan structure, the polar capsule, is remarkably similar to the stinging structures (nemato ...201526627241
laboratory and hatchery-scale evaluation of sand filters and their efficacy at controlling whirling disease infection.in two separate tests rapid sand filtration was evaluated as a means of removing the waterborne triactinomyxon actinospores (tams) of myxobolus cerebralis, the causative agent of salmonid whirling disease, from contaminated water. in the first test we independently evaluated two sizes of sandblast sands: #4010 (effective size, (es) = 250 μm) and #4060 (es = 300 μm). the product number relates to the sand's size composition, and each had a different effective size. effective size is defined by th ...200626599157
assessment of the long-term viability of the myxospores of myxobolus cerebralis as determined by production of the actinospores by tubifex tubifex.while whirling disease was first observed in rainbow trout oncorhynchus mykiss in 1893, the complete life cycle of myxobolus cerebralis (mc), the causative agent of the disease, was not understood until 1984, when it was shown to involve two obligate hosts, a salmonid fish and the aquatic oligochaete tubifex tubifex (tt). the viability of the triactinomyxon (tam) actinospores produced by tt has been well studied, and is known to be temperature dependent and measured in days and weeks. assertions ...201526306333
whirling disease revisited: pathogenesis, parasite biology and disease intervention.whirling disease (wd) is an ecologically and economically debilitating disease of rainbow trout oncorhynchus mykiss caused by the actinosporean spores of the parasite myxobolus cerebralis. m. cerebralis has a complex, 2-host life cycle alternating between salmonid fish and the oligochaete host tubifex tubifex. the parasite alternates between 2 spore forms as transmission stages: an actinosporean triactinomyxon spore that is produced in the oligochaete host and a myxosporean spore that develops i ...201525993890
parental genetic diversity of brown trout (salmo trutta m. fario) brood stock affects offspring susceptibility to whirling disease.whirling disease, caused by the myxozoan parasite myxobolus cerebralis, has high economical and ecological importance worldwide. susceptibility to the disease varies considerably among salmonid species. in brown trout (salmo trutta) the infection is usually subclinical with low mortality, which increases the risk of parasite dissemination, especially when farm fish are used for stocking natural habitats. the influence of intraspecific genetic differences (especially the level of homozygosity) on ...201525886048
rapid natural selection for resistance to an introduced parasite of rainbow trout.introduced species and infectious diseases both independently pose challenges for the preservation of existing biodiversity. however, native species or disease hosts are by no means 'unarmed' when faced with novel environmental challenges, provided that adequate adaptive genetic variation exists to mount effective evolutionary responses. in this study, we examined the consequences of the recently introduced parasite and causative agent of whirling disease (myxobolus cerebralis) in a wild rainbow ...200825567635
counter-insurgents of the blue revolution? parasites and diseases affecting aquaculture and science.aquaculture is the fastest-growing segment of food production and is expected to supply a growing portion of animal protein for consumption by humans. because industrial aquaculture developed only recently compared to industrial agriculture, its development occurred within the context of a growing environmental awareness and acknowledgment of environmental issues associated with industrial farming. as such, parasites and diseases have become central criticisms of commercial aquaculture. this foc ...201425260074
inosine-arginine salt as a promising agent for in vitro activation of waterborne fish-pathogenic myxozoan actinospores.mucus-derived nucleosides serve as key host cues for myxozoan actinospore fish host recognition, but to date their use for experimental actinospore activation in the laboratory or application in disease prevention has not progressed very far. one obstacle has been the low solubility of pure inosine and guanosine. to overcome this, we used inosine-arginine salt (ino-arg), which incorporates both high activation properties and high solubility. we tested its efficacy both in microassays directly ob ...201424991742
myxobolus cerebralis (hofer) infection risk in native cutthroat trout oncorhynchus clarkii (richardson) and its relationships to tributary environments in the yellowstone lake basin.conservation of native species is challenged by the introduction of non-native pathogens and diseases into aquatic and terrestrial environments worldwide. in the yellowstone lake basin, yellowstone national park, the invasive parasite causing salmonid whirling disease myxobolus cerebralis (hofer) has been identified as one factor contributing to population declines of native yellowstone cutthroat trout oncorhynchus clarkii bouvieri (jordan & gilbert). in 2002 and 2003, we examined relationships ...201524953674
survival and reproduction of myxobolus cerebralis-resistant rainbow trout introduced to the colorado river and increased resistance of age-0 progeny.myxobolus cerebralis caused severe declines in rainbow trout populations across colorado following its introduction in the 1980s. one promising approach for the recovery of colorado's rainbow trout populations has been the production of rainbow trout that are genetically resistant to the parasite. we introduced one of these resistant crosses, known as the gr×crr (cross between the german rainbow [gr] and colorado river rainbow [crr] trout strains), to the upper colorado river. the abundance, sur ...201424811066
susceptibility to myxobolus cerebralis among tubifex tubifex populations from ten major drainage basins in colorado where cutthroat trout are endemic.establishment of myxobolus cerebralis (mc) resulted in declines of wild rainbow trout oncorhynchus mykiss populations in streams across colorado during the 1990s. however, the risk for establishment and spread of this parasite into high-elevation habitats occupied by native cutthroat trout o. clarkii was unknown. beginning in 2003, tubificid worms were collected from all major drainages where cutthroat trout were endemic and were assayed by quantitative pcr to determine the occurrence and distri ...201424689955
analysis of regional scale risk of whirling disease in populations of colorado and rio grande cutthroat trout using a bayesian belief network model.introduction and spread of the parasite myxobolus cerebralis, the causative agent of whirling disease, has contributed to the collapse of wild trout populations throughout the intermountain west. of concern is the risk the disease may have on conservation and recovery of native cutthroat trout. we employed a bayesian belief network to assess probability of whirling disease in colorado river and rio grande cutthroat trout (oncorhynchus clarkii pleuriticus and oncorhynchus clarkii virginalis, resp ...201424660663
whirling disease dynamics: an analysis of intervention strategies.whirling disease (wd), a severe and widespread disease of salmonids, is caused by the myxosporean parasite myxobolus cerebralis. it is further characterized by a unique two-host life cycle, utilizing the oligochaete tubifex tubifex as an intermediate host. m. cerebralis is an invasive species that has been affecting populations in the united states including epidemics that killed in excess of 90% of populations in colorado and montana streams within the past 20 years. currently, there is no know ...201424439792
effects of habitat alteration on the epizootiology of myxobolus cerebralis, the causative agent of salmonid whirling disease.whirling disease, caused by the myxozoan parasite myxobolus cerebralis , is a serious health threat to salmonid fish and its control remains problematic. the parasite has a 2-host life cycle involving a salmonid and the aquatic oligochaete tubifex tubifex . a commonly used strategy to control parasites that requires an obligatory invertebrate host is to eliminate or reduce the host population size to a point where parasite transmission can no longer occur. large numbers of t. tubifex are frequen ...201424383542
reduced myxobolus cerebralis actinospore production in a colorado reservoir may be linked to changes in tubifex tubifex population structure.elucidating the dynamics of a parasitic infection requiring two hosts in a natural ecosystem can be a daunting task. myxobolus cerebralis (mc), the myxozoan parasite that causes whirling disease in some salmonids, was detected in the colorado river upstream of windy gap reservoir (wgr) in 1988. subsequently, whirling disease was implicated in the decline of wild rainbow trout oncorhynchus mykiss in the river when wgr was identified as a point source of mc triactinomyxons (tams). between 1997 and ...201323944286
temporal expression patterns of rainbow trout immune-related genes in response to myxobolus cerebralis exposure.infection of salmonids by the myxozoan parasite myxobolus cerebralis can cause whirling disease, which is responsible for high mortalities in rainbow trout hatcheries and natural populations in the united states. although considerable research has provided insight into disease pathology, host invasion, and inheritance patterns of resistance, the causal genetic variants and molecular mechanisms underlying host resistance or susceptibility remain elusive. a previous study found that expression cha ...201323867493
a comparison of two methods for colorimetric in situ hybridization using paraffin-embedded tissue sections and digoxigenin-labeled hybridization probes.two methods for colorimetric in situ dna probe hybridization (cish) assays on paraffin-embedded tissue sections were compared. the heated method used heat (90-100°c) to denature dna in the sample prior to probe hybridization, while the unheated method used a standard hybridization temperature of 42°c. both procedures were tested on tissue samples that harbored the mollusk protozoan pathogens perkinsus marinus, p. chesapeaki, or haplosporidium nelsoni, the protozoan and bacterial fish pathogens m ...201323697605
using real-time pcr and bayesian analysis to distinguish susceptible tubificid taxa important in the transmission of myxobolus cerebralis, the cause of salmonid whirling disease.aquatic oligochaetes have long been appreciated for their value in assessing habitat quality because they are ubiquitous sediment-dwelling filter feeders. many oligochaete taxa are also important in the transmission of fish diseases. distinguishing resistant and susceptible taxa is important for managing fish disease, yet challenging in practice. tubifex tubifex (oligochaeta: tubificidae) is the definitive host for the complex life-cycle parasite, myxobolus cerebralis, the causative agent of sal ...201323474394
agent of whirling disease meets orphan worm: phylogenomic analyses firmly place myxozoa in cnidaria.myxozoa are microscopic obligate endoparasites with complex live cycles. representatives are myxobolus cerebralis, the causative agent of whirling disease in salmonids, and the enigmatic "orphan worm" buddenbrockia plumatellae parasitizing in bryozoa. originally, myxozoa were classified as protists, but later several metazoan characteristics were reported. however, their phylogenetic relationships remained doubtful. some molecular phylogenetic analyses placed them as sister group to or even with ...201323382916
genetic basis of differences in myxospore count between whirling disease-resistant and susceptible strains of rainbow trout.we used a quantitative genetics approach and estimated broad sense heritability (h2b) of myxospore count and the number of genes involved in myxospore formation to gain a better understanding of how resistance to myxobolus cerebralis, the parasite responsible for whirling disease, is inherited in rainbow trout oncorhynchus mykiss. an m. cerebralis-resistant strain of rainbow trout, the german rainbow (gr), and a wild, susceptible strain of rainbow trout, the colorado river rainbow (crr), were sp ...201223269384
myxobolus neurotropus infecting rainbow trout in alaska, a new geographic record.the alaska department of fish and game fish pathology laboratory received a rainbow trout oncorhynchus mykiss from the alaska peninsula that was suspected of having whirling disease based on the display of aberrant swimming behavior and a deformed spine. we tested for myxobolus cerebralis using standard pepsin-trypsin digest and molecular procedures, which yielded negative results. however, many oval shaped myxospores were observed in brain smears and were confirmed to be those of the morphologi ...201223066815
spatial and temporal variation of whirling disease risk in montana spring creeks and rivers.spring creeks are important spawning and rearing areas for wild trout, but the stable flows, cool temperatures, and high nutrient levels that characterize these unique habitats may also make them highly susceptible to establishment and proliferation of the whirling disease pathogen myxobolus cerebralis. we evaluated the spatial and temporal dynamics in whirling disease risk by using sentinel rainbow trout oncorhynchus mykiss fry in nine different spring creeks and their conjoining rivers or rese ...201223025590
biostatic activity of piscine serum and mucus on myxozoan fish infective stages.since the basis of host specificity in myxozoa, i.e. the differential disposition and extinction of erroneously penetrated myxozoan infective stages in non-susceptible fish hosts, remains puzzling, we aimed to explore the role of the innate immune system in this issue. in a comparative incubation challenge of actinospore sporoplasms of the freshwater parasite species myxobolus cerebralis, henneguya nuesslini and myxobolus pseudodispar to isolates of host and non-host muci and blood sera, we meas ...201222951229
comparison of hatchery and field performance between a whirling-disease-resistant strain and the ten sleep strain of rainbow trout.a whirling-disease-resistant strain of rainbow trout oncorhynchus mykiss (grhl strain) derived from a backcross of an f1 hybrid of two strains (german strain x harrison lake strain) with german strain females, was compared with the ten sleep (ts) strain of rainbow trout. the grhl strain had consistently superior growth and feed conversion in two consecutive hatchery trials. hatching and mortality rates were similar between strains. both strains were stocked into two utah reservoirs (hyrum, porcu ...201222838082
invasion and initial replication of ultraviolet irradiated waterborne infective stages of myxobolus cerebralis results in immunity to whirling disease in rainbow trout.myxobolus cerebralis is a microscopic metazoan parasite (phylum myxozoa: myxosporea) associated with salmonid whirling disease. there are currently no vaccines to minimise the serious negative economical and ecological impacts of whirling disease among populations of salmonid fish worldwide. uv irradiation has been shown to effectively inactivate the waterborne infective stages or triactinomyxons of m. cerbralis in experimental and hatchery settings but the mechanisms by which the parasite is co ...201222580732
the effects of myxobolus cerebralis on the physiological performance of whirling disease resistant and susceptible strains of rainbow trout.the development of rainbow trout oncorhynchus mykiss strains that are resistant to whirling disease has shown promise as a management tool for populations in areas where myxobolus cerebralis is present. however, the physiological effects of the disease on characteristics necessary for fish survival in natural river conditions have not been tested in many of these strains. five rainbow trout strains were evaluated for their swimming ability and growth characteristics in relation to m. cerebralis ...201122372244
the parasite that causes whirling disease, myxobolus cerebralis, is genetically variable within and across spatial scales.understanding the genetic structure of parasite populations on the natural landscape can reveal important aspects of disease ecology and epidemiology and can indicate parasite dispersal across the landscape. myxobolus cerebralis (myxozoa: myxosporea), the causative agent of whirling disease in the definitive host tubifex tubifex, is native to eurasia and has spread to more than 25 states in the usa. the small amounts of data available to date suggest that m. cerebralis has little genetic variabi ...201122151695
comparative susceptibility of deschutes river, oregon, tubifex tubifex populations to myxobolus cerebralis.dams along the deschutes river (dr) in central oregon have blocked fish migration for over 40 years. reestablishment of anadromous fish runs above the dams as part of a fish passage plan may introduce fish pathogens, such as myxobolus cerebralis, the myxozoan parasite that causes salmonid whirling disease. this parasite is carried by adult salmon that stray into the dr system during their return to enzootic areas of the upper columbia river basin, and it is now known to be established in at leas ...201121699131
correlation of environmental attributes with histopathology of native yellowstone cutthroat trout naturally infected with myxobolus cerebralis.infection by the invasive parasite myxobolus cerebralis (causing whirling disease in salmonids) is strongly influenced by a stream's physico-chemical characteristics, which might affect host pathology. we examined whether environmental variables of a m. cerebralis-positive tributary to yellowstone lake, yellowstone national park, u.s.a., correlated with the histopathology of naturally infected native cutthroat trout oncorhynchus clarkii bouvieri. host inflammatory response and cranial cartilage ...201121516975
prevalence of myxobolus cerebralis infections among genetic lineages of tubifex tubifex at three locations in the madison river, montana.abstract host biodiversity can impact disease risk and influence the transmission of parasitic disease. stream sediment-dwelling worms, tubifex tubifex (clitellata: oligochaeta), are the definitive host of the parasite myxobolus cerebralis (myxozoa: myxosporea), which causes whirling disease in salmonid fishes. genetic diversity of t. tubifex is correlated with host susceptibility to m. cerebralis , and mitochondrial lineage iii is generally shown to be more likely to be infected and produce the ...201121506853
no shot in the dark: myxozoans chemically detect fresh fish.this work reports the discovery of an hitherto unknown chemical recognition trait enabling a parasitic life cycle in aquatic habitats. we believe this is the first record of a natural, host-derived chemical molecule identified as a recognition cue for the phylum myxozoa. the actinospores of these parasites attach to fish hosts via polar filaments that are extruded upon mechanical stimulation after preceding recognition of a chemical trigger contained in surface mucus. our goal was to identify th ...201021087611
analysis of rainbow trout oncorhynchus mykiss epidermal mucus and evaluation of semiochemical activity for polar filament discharge in myxobolus cerebralis actinospores.as myxozoan actinospores are stimulated by fish epidermal mucus to attach to their hosts via extrusion of filaments from specialized organelles, the polar capsules, mucus components were tested for discharge triggering activity on myxobolus cerebralis actinospores. using various methodological approaches, a selective exclusion of candidate substances based on experimental outcome is provided and the physiochemical traits of the putative agents are explored to create a basis for the isolation of ...201021078020
a major effect quantitative trait locus for whirling disease resistance identified in rainbow trout (oncorhynchus mykiss).whirling disease, caused by the pathogen myxobolus cerebralis, leads to skeletal deformation, neurological impairment and under certain conditions, mortality of juvenile salmonid fishes. the disease has impacted the propagation and survival of many salmonid species over six continents, with particularly negative consequences for rainbow trout. to assess the genetic basis of whirling disease resistance in rainbow trout, genome-wide mapping was initiated using a large outbred f(2) rainbow trout fa ...201021048672
the effects of myxobolus cerebralis on apache and gila trout in laboratory exposures.whirling disease has been implicated in salmonid population declines in several western states. to determine the risk of a species or strain of salmonid to whirling disease it is critical to establish its relative susceptibility to myxobolus cerebralis infection. gila trout oncorhynchus gilae and apache trout oncorhynchus gilae apache were exposed to various doses of m. cerebralis triactinomyxons (tams) in laboratory experiments. in trials conducted in consecutive years, fish were exposed to tam ...201020848882
effect of cadmium on the susceptibility of tubifex tubifex to myxobolus cerebralis (myxozoa), the causative agent of whirling disease.environmental pollutants alter a wide range of host-parasite interactions in various ways. in some cases, pollution leads to a significant increase in parasite abundance, causing epidemics of parasitic diseases. in other cases, toxicants restrict the transmission success of parasites, resulting in reduction of their abundance. however, very little is known regarding whether and to what extent aquatic pollution affects myxozoan obligate parasites commonly found in fish. we investigated the effect ...201020391913
expression of immune-regulatory genes, arginase-2 and inducible nitric oxide synthase (inos), in two rainbow trout (oncorhynchus mykiss) strains following exposure to myxobolus cerebralis.the present endeavor was conducted to evaluate the role of activated macrophage in the susceptibility of two different rainbow trout (oncorhynchus mykiss) strains, a susceptible american (t) and a more resistant german (h), to infection with myxobolus cerebralis. arginase-2 and inducible nitric oxide synthase (inos) genes were used as references to the alternative and classical pathway of macrophage activation. the expression level of both genes was measured using quantitative real-time polymera ...201019894064
epizootiology of myxobolus cerebralis, the causative agent of salmonid whirling disease in the rock creek drainage of west-central montana: 2004-2008.whirling disease, caused by the myxozoan parasite myxobolus cerebralis , remains a serious health threat to salmonid fish in the western united states. a previously published study on the epizootiology of whirling disease in the rock creek watershed of west-central montana, conducted from 1998 to 2003, showed that the intensity of m. cerebralis infections in sentinel trout increased significantly throughout the drainage and that the range of m. cerebralis had expanded considerably. in addition, ...201019891515
propagation of the myxozoan parasite myxobolus cerebralis by different geographic and genetic populations of tubifex tubifex: an oregon perspective.tubifex tubifex are obligate invertebrate hosts in the life cycle of myxobolus cerebralis, the myxozoan parasite that causes whirling disease in salmonid fishes. this exotic parasite is established to varying degrees across oregon's columbia river system (pacific northwest, usa) and characteristics of local t. tubifex populations likely play a role in the pattern of disease occurrence. to better understand these patterns, we collected t. tubifex from three oregon river basins (willamette, deschu ...200919583968
in vivo exposure of susceptible and non-susceptible fish species to myxobolus cerebralis actinospores reveals non-specific invasion behaviour.due to controversial previous results, it has been unclear whether myxobolus cerebralis (myxosporea, myxozoa) is able to specifically choose a salmonid host by selective attachment and penetration. using a novel in vivo tracking assay that employs fluorescence staining of actinospore sporoplasms, we demonstrate a lack of host specificity of m. cerebralis actinospores during their initial invasion reactions. fish were experimentally exposed to stained actinospores that could be detected as emitte ...200919476282
the life cycle of myxobolus lentisuturalis (myxozoa: myxobolidae), from goldfish (carassius auratus auratus), involves a raabeia-type actinospore.we studied a natural infection of the oligochaete branchiura sowerbyi beddard, 1892 with the raabeia-type actinosporean stage of myxobolus lentisuturalis dyková, fiala et nie, 2002 which infected goldfish carassius auratus auratus (l.) in italy, using molecular analysis of the ssu rrna gene. the existence of intraoligochaete development shows that this parasite follows the life-cycle pattern described by wolf and markiw (1984) for myxobolus cerebralis. histological examinations of the goldfish i ...200919391327
myxobolus cerebralis (myxozoa), the causative agent of whirling disease, reduces fecundity and feeding activity of tubifex tubifex (oligochaeta).myxobolus cerebralis is the causative agent of whirling disease that has significant economical and ecological impacts on trout populations. although intensive studies have been conducted to understand its effects on and interactions with its fish host, only limited information is available about how and to what extent m. cerebralis affects its oligochaete host, tubifex tubifex. we investigated the effects of m. cerebralis on survival, growth, reproduction, and feeding activity of t. tubifex. ma ...200919284888
differentially expressed parasite genes involved in host recognition and invasion of the triactinomyxon stage of myxobolus cerebralis (myxozoa).the host recognition and invasion process of myxobolus cerebralis actinospores (triactinomyxon, tam) was studied on a genetic level. a small-scale in vitro assay was developed to activate a large number of tams simultaneously, and to monitor the host invasion in the absence of live fish. the transcriptomes of non-activated and in vitro-activated tams were compared by suppressive subtractive hybridization (ssh) to identify parasite genes involved in the host invasion process. differential screeni ...200919195410
potential for dissemination of the nonnative salmonid parasite myxobolus cerebralis in alaska.myxobolus cerebralis, the myxozoan parasite responsible for whirling disease in salmonids, was first introduced into the united states in 1958 and has since spread across the country, causing severe declines in wild trout populations in the intermountain western united states. the recent detection of the parasite in alaska is further evidence of the species' capability to invade and colonize new habitat. this study qualitatively assesses the risk of further spread and establishment of m. cerebra ...200818942590
effects of freezing, drying, ultraviolet irradiation, chlorine, and quaternary ammonium treatments on the infectivity of myxospores of myxobolus cerebralis for tubifex tubifex.the effects of freezing, drying, ultraviolet irradiation (uv), chlorine, and a quaternary ammonium compound on the infectivity of the myxospore stage of myxobolus cerebralis (the causative agent of whirling disease) for tubifex tubifex were examined in a series of laboratory trials. freezing at either -20 degrees c or -80 degrees c for a period of 7 d or 2 months eliminated infectivity as assessed by the absence of production of the actinospore stage (triactinomyxons [tams]) from t. tubifex cult ...200818783133
differences in viability and reactivity of actinospores of three myxozoan species upon ageing.little is known about the viability of myxozoan actinospore stages after harvest from laboratory cultures of infected oligochaete worms. the viability and reactivity of actinospores of three myxozoan species was evaluated after short-term storage at 4 degrees c and 12 degrees c. two methods of determining actinospore viability were compared: differential fluorescent staining and direct microscopic observation of morphological indicators of spore integrity. spore reactivity was quantified by meas ...200818666413
variability in triactinomyxon production from tubifex tubifex populations from the same mitochondrial dna lineage infected with myxobolus cerebralis, the causative agent of whirling disease in salmonids.myxobolus cerebralis, the causative agent of whirling disease, infects both salmonid fish and an aquatic oligochaete, tubifex tubifex. although m. cerebralis has been detected in river drainages throughout the united states, disease severity among wild fish populations has been highly variable. tubifex tubifex populations have been genetically characterized using sequences from the 16s mitochondrial dna (mtdna) gene, the 18s ribosomal rna gene, the internal transcribed spacer region 1 (its1), an ...200818605778
a new species of myxozoan (myxosporea) from the brain and spinal cord of rainbow trout (oncorhynchus mykiss) from idaho.a new species of myxosporea, myxobolus neurotropus n. sp., is described from the brain and spinal cord of rainbow trout (oncorhynchus mykiss) from duncan creek, owyhee county, idaho. spores are oval, have 2 pyriform polar capsules, and possess a thick spore wall (sutural rim) with a short intracapsular offshoot. the mean spore dimensions are length 11.8 microm, width 10.8 microm, and thickness 8.8 microm. this myxozoan is compared to other described myxobolus species found in cranial tissues of ...200818372644
a packed-bed filtration system for collection of myxobolus cerebralis triactinomyxons.information on the distribution and abundance of myxobolus cerebralis triactinomyxons in natural systems is limited because direct and accurate sampling methods for this life stage have not been developed. existing methods are based on indirect measures of triactinomyxon densities and are therefore confounded. direct estimation of triactinomyxon concentrations would more exactly pinpoint the ambient infection risk to wild fish and allow evaluation of management strategies designed to mitigate th ...200718333480
tubifex tubifex from alaska and their susceptibility to myxobolus cerebralis.although widespread throughout the continental united states, myxobolus cerebralis, the myxozoan parasite that causes whirling disease in salmonids, has not been reported from the state of alaska. as part of a risk assessment for the introduction and establishment of m. cerebralis into alaska, the distribution of the invertebrate host tubifex tubifex was surveyed, and its genetic composition and susceptibility to the parasite were determined. many oligochaetes, but no t. tubifex, were collected ...200718314677
use of site occupancy models to estimate prevalence of myxobolus cerebralis infection in trout.empirical estimates of pathogen prevalence in samples of fish may underestimate true prevalence because available detection techniques are incapable of perfect detection. trout of several species were collected from enzootic (myxobolus cerebralis, causative agent in whirling disease) habitats, and individual fish were examined for presence of the parasite two or six times by one of four methods: pepsin-trypsin digest (brown trout salmo trutta), plankton centrifuge (brown trout), polymerase chain ...200718236627
discovery of genes implicated in whirling disease infection and resistance in rainbow trout using genome-wide expression profiling.whirling disease, caused by the pathogen myxobolus cerebralis, afflicts several salmonid species. rainbow trout are particularly susceptible and may suffer high mortality rates. the disease is persistent and spreading in hatcheries and natural waters of several countries, including the u.s.a., and the economic losses attributed to whirling disease are substantial. in this study, genome-wide expression profiling using cdna microarrays was conducted for resistant hofer and susceptible trout lodge ...200818218127
effects of water flow on the infection dynamics of myxobolus cerebralis.myxobolus cerebralis, the myxozoan parasite responsible for whirling disease in salmonid fishes, has a complex life-cycle involving an invertebrate host and 2 spore stages. water flow rate is an environmental variable thought to affect the establishment and propagation of m. cerebralis; however, experimental data that separates flow effects from those of other variables are scarce. to compare how this parameter affected parasite infection dynamics and the invertebrate and vertebrate hosts, dead, ...200818053292
characterization of glycans in the developmental stages of myxobolus cerebralis (myxozoa), the causative agent of whirling disease.glycans and sugar-binding molecules (lectins) form an interactive recognition system, which may enable parasitic organisms to adhere to host cells and migrate into target tissues. the aim of the present study was to analyse surface-associated glycans in the developmental stages of myxobolus cerebralis (hofer), the causative agent of whirling disease. a panel of biotin-labelled plant lectins was used to detect a broad spectrum of glycan motifs with high specificity. binding sites were detected hi ...200717958607
arrested development of the myxozoan parasite, myxobolus cerebralis, in certain populations of mitochondrial 16s lineage iii tubifex tubifex.laboratory populations of tubifex tubifex from mitochondrial (mt)16s ribosomal dna (rdna) lineage iii were generated from single cocoons of adult worms releasing the triactinomyxon stages (tams) of the myxozoan parasite, myxobolus cerebralis. subsequent worm populations from these cocoons, referred to as clonal lines, were tested for susceptibility to infection with the myxospore stages of m. cerebralis. development and release of tams occurred in five clonal lines, while four clonal lines showe ...200817891544
sequence analysis of omnramp alpha and quantitative expression of nramp homologues in different trout strains after infection with myxobolus cerebralis.salmonid whirling disease caused by the metazoan parasite myxobolus cerebralis is an ongoing problem in wild and farmed rainbow trout oncorhynchus mykiss populations. rainbow trout from different strains vary in susceptibility to the parasite. identification of underlying mechanisms could be a starting point for improved control of the disease. we conducted infection trials using 2 rainbow trout strains and brown trout salmo trutta fario, a species not susceptible to the parasite, to investigate ...200717803108
myxozoan transmission via actinospores: new insights into mechanisms and adaptations for host invasion.various mechanisms that enable and improve transmission success of myxozoan actinospore stages towards fish hosts are described, based upon a combination of experimental data and functional analysis of morphological characters. for this purpose, laboratory-reared actinospores of myxobolus cerebralis, myxobolus parviformis, henneguya nuesslini and myxobolus pseudodispar were employed to exemplarily investigate aspects of host attachment and invasion. the process of polar filament discharge of m. ...200717662162
expanded geographical distribution of myxobolus cerebralis: first detections from alaska.the parasite responsible for salmonid whirling disease, myxobolus cerebralis, was introduced to the usa in 1958. it has since spread across the country causing severe declines in wild trout populations, but has never been documented from alaska. however, while assessing the risk of introduction of m. cerebralis into the state, we detected the parasite using a species-specific polymerase chain reaction (pcr) assay. testing of 180 hatchery rainbow trout, oncorhynchus mykiss (walbaum), by pepsin tr ...200717640251
relative quantification of immune-regulatory genes in two rainbow trout strains, oncorhynchus mykiss, after exposure to myxobolus cerebralis, the causative agent of whirling disease.expression of immune-regulatory genes that code for cyclooxigenase-2 (cox-2), transforming growth factor beta (tgf-beta), and two isoforms of interleukin-1beta (il-1beta1 and il-1beta2) was studied in susceptible and non-susceptible rainbow trout strains for 200 days after exposure to myxobolus cerebralis. expression of cox-2, il-1beta1, and il-1beta2 increased 5 min post exposure (p.e.) and was always more elevated in the susceptible strain than in the non-susceptible strain. in both strains, e ...200717530478
epizootiology of myxobolus cerebralis, the causative agent of salmonid whirling disease in the rock creek drainage of west-central montana.whirling disease, caused by the myxozoan parasite myxobolus cerebralis, remains a health threat to salmonid fish in the western united states. although various aspects of this host-parasite system have been studied, investigations examining the overall epizootiology of whirling disease in an ecosystem are lacking. therefore, in june 1998, studies were initiated in the rock creek watershed of west-central montana and continued through 2003 to assess the intensity of infection in trout using senti ...200717436949
evaluation of a range of doses of ultraviolet irradiation to inactivate waterborne actinospore stages of myxobolus cerebralis.the ability of a range of doses of ultraviolet irradiation (uv) to inactivate the waterborne actinospore or triactinomyxon stages (tams) of myxobolus cerebralis was evaluated by infectivity for juvenile rainbow trout oncorhynchus mykiss. tams were uv-irradiated using a low pressure mercury vapour lamp collimated beam apparatus. all doses 40, 80, 120 and 160 mj cm(-2) were found to completely inactivate the tams as demonstrated by the absence of microscopic lesions, myxospores and parasite dna de ...200717432040
isolation of a subtilisin-like serine protease gene (myxsubtsp) from spores of myxobolus cerebralis, the causative agent of whirling disease.proteases play important roles in parasite life cycles and host-parasite interactions. they are pathogenesis factors of many pathogenic organisms and are hence potential targets for chemotherapeutic treatment of disease. we identified a subtilisin-like serine protease gene, myxsubtsp, expressed by myxobolus cerebralis. after pcr with subtilisin-like serine protease primers, the gene was cloned, sequenced and aligned against the ncbi database. its corresponding amino acid sequence included the pu ...200717330744
myxobolus cerebralis infection patterns in yellowstone cutthroat trout after natural exposure.salmonid species and sub-species exhibit a range of susceptibility to myxobolus cerebralis infection. little is known about lesion severity and location, or time required for m. cerebralis myxospores to develop in yellowstone cutthroat trout oncorhynchus clarki bouvieri. in 2002 we performed three 10 d exposures of yellowstone cutthroat trout fry in pelican creek, an m. cerebralis-positive tributary to yellowstone lake. at 90 and 150 d post-exposure we examined the fish for clinical signs, for i ...200617058600
detection of early stages of myxobolus cerebralis in fin clips from rainbow trout (orynchus mykiss).a nested polymerase chain reaction (pcr) assay was used to detect early stages of myxobolus cerebralis in caudal and adipose fin samples from rainbow trout (rt). to determine sensitivity, groups of 10 rt were exposed to 2,000 m. cerebralis triactinomyxons/fish for 1 hour at 15 degrees c and subsequently moved to clean recirculating water. fish were held for 2 and 6 hours and 1, 2, 3, 5, 7, 10, 30, and 60 days before sampling by nonlethal fin biopsy. nested pcr performed on fin clips showed that ...200616789717
risk of myxobolus cerebralis infection to rainbow trout in the madison river, montana, usa.myxobolus cerebralis, the parasite that causes salmonid whirling disease, has had detrimental effects on several salmonid populations in the intermountain west, including the rainbow trout in the madison river, montana, usa. the goal of this study was to examine relationships among characteristics of the environment, tubifex tubifex (the alternate host) populations, and rainbow trout whirling disease risk in the madison river. environmental characteristics were measured in side channels of the m ...200616711061
evaluation of quantitative real-time pcr for rapid assessments of the exposure of sentinel fish to myxobolus cerebralis.pathogen-free rainbow trout (oncorhynchus mykiss) aged 735 degree days were experimentally exposed to a low dose of infectious myxobolus cerebralis (20 triactinomyxons fish(-1)). three time periods were chosen for sampling that included 10 days (d), 67 d, and 5 months (mo) post exposure. five diagnostic assays were used: (1) conventional single-round polymerase chain reaction (pcr), (2) nested pcr, (3) real-time taqman pcr, (4) pepsin-trypsin digest, and (5) histopathology. m. cerebralis was det ...200616555100
interactions among two strains of tubifex tubifex (oligochaeta: tubificidae) and myxobolus cerebralis (myxozoa).host-parasite interactions influence host population growth, host evolution and parasite success. we examined the interactions among myxobolus cerebralis, the parasite that causes salmonid whirling disease, and resistant and susceptible strains of the oligochaete host tubifex tubifex. strains of t. tubifex with diverse genotypes often coexist in nature and have variable susceptibilities to m. cerebralis infection. further, parasite proliferation differs by several orders of magnitude among t. tu ...200616532604
construction and screening of a cdna library from the triactinomyxon spores of myxobolus cerebralis, the causative agent of salmonid whirling diseases.the zap express cdna library was constructed using mrna extracted from the triactinomyxon spores of myxobolus cerebralis. first-strand cdna was synthesized using moloney murine leukaemia virus reverse transcriptase. following second-strand cdna synthesis, the double-stranded cdna was digested with xho i restriction enzyme, cdna fragments less than 400 bp were removed and the remaining cdna was ligated with the lambda zap express vector. the recombinants were packaged in vitro using gigapack iii ...200616388692
the effect of cohabitation of tubifex tubifex (oligochaeta: tubificidae) populations on infections to myxobolus cerebralis (myxozoa: myxobolidae).the competitive interactions between susceptible and resistant tubifex tubifex (oligochaeta: tubificidae) exposed to myxobolus cerebralis (myxozoa: myxobolidae) infections were investigated in two laboratory trials. competition was assessed by the total parasite production over the course of the trials in mixed and pure cultures of m. cerebralis exposed worms, and by the genetic analyses of worms from the control and experimental groups at the beginning and end of the experiments. mixed cultures ...200616321396
development of a rapid assay for the diagnosis of myxobolus cerebralis in fish and oligochaetes using loop-mediated isothermal amplification.a loop-mediated isothermal amplification assay was developed for the rapid detection of myxobolus cerebralis in both fish and oligochaete hosts. the assay was optimized to amplify parasitic dna by incubation with bst dna polymerase and a set of six specially constructed primers at 65 degrees c for 60 min. the amplification products were detected visually using sybr green i dye which gave identical results to gel electrophoresis analysis. parasite dna was detected from infected oligochaetes, and ...200516266328
polar filament discharge of myxobolus cerebralis actinospores is triggered by combined non-specific mechanical and chemical cues.this study presents initial evidence for the requirement of both chemical and mechanical stimuli to discharge polar capsules of myxobolus cerebralis actinospores, the causative agent of salmonid whirling disease. the obligate need for combined discharge triggers was concluded from data obtained in a before/after experimental set-up carried out with individual locally immobilized actinospores. homogenized rainbow trout mucus as chemostimulus and tangency of the apical region of the spores to achi ...200516255819
characterisation of carbohydrate-binding sites in developmental stages of myxobolus cerebralis.glycans and lectins (carbohydrate-binding molecules) form a mutual recognition system, which enables parasitic organisms to attach themselves to the host cells and/or take part in the migration of their developmental stages into the target tissue. the aim of the present study was to identify and characterise the potential binding activity of glycoconjugates in different developmental stages of myxobolus cerebralis, the causative agent of whirling disease in salmonids. the binding patterns of 13 ...200516211413
lectin blot studies on proteins of myxobolus cerebralis, the causative agent of whirling disease.it is known that myxobolus cerebralis antigens, both surficial and secreted, are key modulators for, or targets of, host immune system compounds. we undertook sds-page glycoprotein characterisation of m. cerebralis developmental stages isolated from infected rainbow trout and western blot analyses using selected biotin-labelled plant lectins (gsa-i, pha-e, sja, gsa-ii) and anti-triactinomyxon polyclonal antibodies. glycoproteins were isolated with lectin-affinity chromatography, and prominent ba ...200516119891
effects of fish age versus size on the development of whirling disease in rainbow trout.we examined the effects of both fish age and size on the development of resistance to whirling disease in erwin strain rainbow trout. previously, we demonstrated that juvenile rainbow trout became resistant to development of the disease when first exposed to triactinomyxons of the parasite myxobolus cerebralis at about 9 wk post-hatch when raised at 12 degrees c, but ages and sizes of fish used in that experiment were confounded (ryce ekn, zale av, macconnell e [2004] dis aquat org 59:225-233). ...200515759802
differential propagation of the metazoan parasite myxobolus cerebralis by limnodrilus hoffmeisteri, ilyodrilus templetoni, and genetically distinct strains of tubifex tubifex.whirling disease, caused by the parasite myxobolus cerebralis, has infected rainbow trout (oncorhynchus mykiss) and other salmonid fish in the western united states, often with devastating results to native populations but without a discernible spatial pattern. the parasite develops in a complex 2-host system in which the aquatic oligochaete tubifex tubifex is an obligate host. because substantial differences in whirling disease severity in different areas of north america did not seem explainab ...200415715230
phylogenetic comparison of the myxosporea based on an actin cdna isolated from myxobolus cerebralis.the full-length actin gene from myxobolus cerebralis (mceract-1), the first characterized from representatives in the phylum myxozoa, encodes a 378-amino acid polypeptide with an estimated molecular weight of 41,580-da. a phylogenetic comparison found m. cerebralis to branch outside the metazoans. this finding contrasts with previous reports that suggest an evolutionary affinity of the myxozoa with either the bilateria or cnidaria.200415666723
real-time quantitative polymerase chain reaction (qpcr) to identify myxobolus cerebralis in rainbow trout oncorhynchus mykiss.this study describes the development of a taqman real-time quantitative polymerase chain reaction (qpcr) technique using the heat-shock protein 70 (hsp 70) and 18s ribosomal dna (18s rdna) sequences to identify myxobolus cerebralis and attempt to quantify infection severity within rainbow trout fry oncorhynchus mykiss. rainbow trout for this study were exposed to m. cerebralis under natural river conditions and examined for infection by histology, polymerase chain reaction (pcr) and qpcr analysi ...200415521319
myxobolus cerebralis internal transcribed spacer 1 (its-1) sequences support recent spread of the parasite to north america and within europe.molecular approaches for resolving relationships among the myxozoa have relied mainly on small subunit (ssu) ribosomal dna (rdna) sequence analysis. this region of the gene is generally used for higher phylogenetic studies, and the conservative nature of this gene may make it inadequate for intraspecific comparisons. previous intraspecific studies of myxobolus cerebralis based on molecular analyses reported that the sequence of ssu rdna and the internal transcribed spacer (its) were highly conse ...200415460854
extensive release of an antigen associated with the sporogonic stages of myxobolus cerebralis (myxozoa: myxosporea) is detected by a heterologous antibody raised to tetracapsuloides bryosalmonae (myxozoa: malacosporea).monoclonal antibody b4 (mab b4) was previously developed to the myxozoan parasite tetracapsuloides bryosalmonae canning, curry, feist, longshaw et okamura, 1999, the causative agent of proliferative kidney disease of salmonids, here we describe the reaction of mab b4 against myxobolus cerebralis hofer, 1903, the parasite that causes 'whirling disease' in salmonids. tissues examined were collected from experimentally infected rainbow trout oncorhynchus mykiss (walbaum) and the aquatic oligochaete ...200415357400
identification of a serine protease gene expressed by myxobolus cerebralis during development in rainbow trout oncorhynchus mykiss.serine proteases have been recognized as key factors in parasite physiology and disease development. we have identified a serine protease gene from myxobolus cerebralis, myxsp-1, the myxozoan parasite causing whirling disease in salmonid fishes. the amino acid sequence, as deduced from the cdna sequence, included a catalytic residue arrangement similar to that of the chymotrypsin family of serine proteases. a real-time taqman polymerase chain reaction (pcr) analysis revealed differences in the t ...200415264720
effects of fish age and parasite dose on the development of whirling disease in rainbow trout.we determined the ages at which juvenile rainbow trout oncorhynchus mykiss became resistant to the effects of whirling disease following exposure to a range of parasite doses. heretofore, the development and severity of whirling disease in salmonids was known to be generally dependent on the age or size of fish when first exposed to the triactinomyxon spores of myxobolus cerebralis; larger, older individuals tended to be less diseased. however, no systematic determination had been made of the ex ...200415264719
evaluation of five diagnostic methods for the detection and quantification of myxobolus cerebralis.diagnostic methods were used to identify and quantify myxobolus cerebralis, a myxozoan parasite of salmonid fish. in this study, 7-week-old, pathogen-free rainbow trout (oncorhynchus mykiss) were experimentally infected with m. cerebralis and at 7 months postinfection were evaluated with 5 diagnostic assays: 1) pepsin-trypsin digest (ptd) to detect and enumerate spores found in cranial cartilage, 2) 2 different histopathology grading scales that provide a numerical score for severity of microsco ...200415152834
comparative susceptibility of atlantic salmon, lake trout and rainbow trout to myxobolus cerebralis in controlled laboratory exposures.the susceptibility of lake trout salvelinus namaycush, rainbow trout oncorhynchus mykiss and atlantic salmon salmo salar to myxobolus cerebralis, the causative agent of whirling disease, was compared in controlled laboratory exposures. a total of 450 (225 for each dose) fry for each species were exposed to a low (200 spores per fish) or high (2000 spores per fish) dose of the infective triactinomyxon. at 22 wk post-exposure, 60 fish from each group, as well as controls for each species, were exa ...200415038448
myxobolus cerebralis: identification of a cathepsin z-like protease gene (myxcp-1) expressed during parasite development in rainbow trout, oncorhynchus mykiss.cysteine proteases are essential to the biological function of parasitic organisms and are gaining interest as the target of chemotherapeutics aimed at their control. we report a cysteine protease gene from the myxozoan myxobolus cerebralis, the cause of whirling disease in salmonid fish. the mature gene (myxcp-1) encodes a 248-amino acid polypeptide that includes catalytic residues similar to the papain family of cysteine proteases. myxcp-1 features a propeptide region and sequence insertions t ...200314990313
efficacy of passive sand filtration in reducing exposure of salmonids to the actinospore of myxobolus cerebralis.the aquatic oligochaete tubifex tubifex parasitized by myxobolus cerebralis releases triactinomyxon (tam) actinospores that can infect some species of salmonids and cause salmonid whirling disease. silica sand was tested as a filtration medium for removal of tams from water containing the parasite. laboratory tests indicated sand filtration removed > 99.99% of tams. in 2 different field tests, groups of 1 mo old rainbow trout oncorhynchus mykiss were exposed for 2 wk to filtered and unfiltered w ...200314735924
sds-page and western blot analysis of triactinomyxon spores of myxobolus cerebralis, the cause of whirling disease in salmonid fish. 200314653320
whirling disease of salmonid fish: life cycle, biology, and disease.myxobolus cerebralis is the myxozoan parasite responsible for causing whirling disease in salmonid fish. although the parasite was first described nearly 100 yr ago, it received relatively little attention until the discovery of its 2-host life cycle in the mid 1980s. this was the first, complete, myxozoan life cycle to be described, and it was greeted with some skepticism because it united 2 stages of m. cerebralis that were previously classified in 2 separate taxa. in the last decade, there ha ...200314533670
histologic study of head cartilage degeneration in rainbow trout (oncorhynchus mykiss) infected with the parasite myxobolus cerebralis.a light microscopy study of head cartilage tissue in rainbow trout alevins (oncorhynchus mykiss) infected with the parasite myxobolus cerebralis showed that, regardless of the presence or absence of whirling disease symptoms such as black tail and whirling swimming due to altered tail and spine morphology, some fish presented large amounts of spores lodged in the head after three months of infection. the spores were located in regions where the cartilage was extensively destroyed.200312974324
susceptibility of two strains of rainbow trout (one with suspected resistance to whirling disease) to myxobolus cerebralis infection.the susceptibility of 2 strains of rainbow trout oncorhynchus mykiss, 1 from north america (tl) and 1 from germany (gr), to myxobolus cerebralis (the cause of salmonid whirling disease) was assessed following exposure to the infectious stages (triactinomyxons). two laboratory experiments were conducted with age-matched rainbow trout of each strain. at the beginning of the study, the 2 trout strains were aged ca. 570 degree-days in expt 1, and ca. 999 degree-days in expt 2. in both experiments, r ...200312887253
detection of myxozoan parasites in oligochaetes imported as food for ornamental fish.to determine the potential for dissemination of myxozoan parasites by transfer of their alternate oligochaete hosts, shipments of tubificid worms obtained from an overseas commercial aquarium supplier were screened for actinospore stages of myxozoan parasites. at least 7 different triactinomyxon types were identified. the morphological characteristics of the actinospores recovered from these tubificids shared characteristics with triactinomyxons characterized in other surveys, particularly from ...200312659308
effects of water temperature and substrate type on spore production and release in eastern tubifex tubifex worms infected with myxobolus cerebralis.eastern tubifex tubifex worms were exposed to myxobolus cerebralis spores at 9, 13, 17, and 20 c in 1-l jars that contained sand, mud, or leaf litter as substrata. beginning 60 days after exposure, water from each jar was filtered daily and examined for the presence of waterborne triactinomyxon spores (tams). on discovering a single tam from an experimental jar, 48 t. tubifex worms from that jar were placed individually into 24-well plates. spores released from individual infected t. tubifex wor ...200312659298
physical and chemical effects on viability of the myxobolus cerebralis triactinomyxon.various chemical and physical methods for destroying the triactinomyxon (tam) stage of the myxozoan parasite myxobolus cerebralis were tested. the fluorescent stains propidium iodide and fluorescein diacetate were used as indicators of viability. physical variables tested included freezing, drying, high temperature, sonication, and pressure of 6.2 x 10(7) pa (9000 psi). chemicals evaluated included chlorine bleach, povidone-iodine, and hydrogen peroxide. freezing or drying for 1 h was effective ...200312650246
study of the tail fin rays of rainbow trout (oncorhynchus mykiss) infected with the parasite myxobolus cerebralis.a light, transmission and scanning microscope study of the rays (lepidotrichia) forming the tail fin of rainbow trout (oncorhynchus mykiss) fingerlings infected with the parasite myxobolus cerebralis showed that triactinomyxon adherence to the tail fin of host fingerlings occurred 10 min after infection. after 2 h of exposure, it was possible to observe triactinomyxon spores in the epidermis. although the characteristic symptoms of the disease, such as a black tail and a change in tail morpholog ...200212408363
prevalence and susceptibility of infection to myxobolus cerebralis, and genetic differences among populations of tubifex tubifex.the prevalence of infection and susceptibility of the aquatic oligochaete tubifex tubifex to myxobolus cerebralis, was examined in 2 studies on the upper colorado river, colorado, usa, where whirling disease occurs in wild trout populations. in the first study, the prevalence of infection ranged from 0.4 to 1.5%, as determined by counting the number of t. tubifex releasing triactinomyxons of m. cerebralis directly following their collection from the field. the susceptibility of those t. tubifex ...200212363083
validation of a single round polymerase chain reaction assay for identification of myxobolus cerebralis myxospores.validation of a single round pcr-based assay to confirm as myxobolus cerebralis myxospores obtained from pepsin-trypsin digest preparations is described. the assay is a modification of a pcr assay published previously, based on the amplification of a segment of the gene encoding the 18s ribosomal subunit of m. cerebralis. the sensitivity, specificity and upper and lower detection limits were determined using known m. cerebralis and non-m. cerebralis myxospores and m. cerebralis-free fish. the se ...200212113304
response of rainbow trout oncorhynchus mykiss to exposure to myxobolus cerebralis above and below a point source of infectivity in the upper colorado river.we exposed 9 wk old rainbow trout oncorhynchus mykiss to ambient levels of myxobolus cerebralis infectious stages at 4 sites of suspected differing infectivity in the colorado river. exposure was estimated by periodic filtration of river water at each exposure location. after a 32 d exposure, the fish were held in the colorado river at a common site for over a year. resulting infection was evaluated by the presence of clinical signs (whirling behavior, cranial deformity/exophthalmia, and black t ...200212113302
factors influencing the distribution of myxobolus cerebralis, the causative agent of whirling disease, in the cache la poudre river, colorado.oligochaetes, triactinomyxons (tams), and age-0 trout were sampled in the upper cache la poudre river, colorado, to determine the distribution of myxobolus cerebralis during 1997 and 1998. densities of the intermediate host, the oligochaete tubifex tubifex, were 3.5 orders of magnitude higher in the m. cerebralis-infected poudre rearing unit (pru) trout rearing ponds than at any of the river sampling reaches. oligochaetes, including t. tubifex, were rare in the river (1 oligochaete m(-2)), excep ...200212093042
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