First Myxozoan Infection (Cnidaria: Myxosporea) in a Marine Polychaete from North America and Erection of Actinospore Collective Group Saccimyxon

In a survey of marine annelids for myxosporean infection in Charleston Harbor, South Carolina, we collected 3,214 polychaetes from 21 families and found infections in 6 spionid individuals. Based on gross morphology and COI sequencing, all infected spionids were identified as Streblospio benedicti. Infection prevalence was 0.8% (6/734) of that species of spionid, and 0.2% of all 3,214 polychaetes examined. Pansporocysts contained 8 actinospores and developed in the tegument of the annelid host. This is the first myxozoan infection recorded from this polychaete species, second in the family, and the first marine myxozoan found in the Americas. It is the first marine species found to develop in the tegument of its annelid host; a site of development observed only once before, in Ceratonova shasta infections of its freshwater sabellid polychaete host. Mature actinospores were morphologically simple, truncated ellipsoids, lacking processes or ornamentation, 9.0 ± 0.5 μm × 6.0 ± 0.4 μm. Their sack-like shape was similar to 9 of the 12 actinospores described previously from polychaetes; 10/12 had been and ascribed originally to the morphological collective group Tetractinomyxon despite 9 of these having few similarities to the original description of this group. We propose to name the simple, spherical to ellipsoidal spore morphotype Saccimyxon to encompass both our novel actinospore and the 9 other sack-like polychaete actinospore types in the literature. In the present study, 18S rDNA sequencing demonstrated that the myxozoans that infected the 6 spionids were genetically the same species (type sample 1,737 nucleotides, GenBank accession number MH791159) and was not >95% similar to any sequence in GenBank. Phylogenetic analysis showed that the myxozoan species we encountered is basal to the kudoids and thus likely to have a morphologically simple myxospore stage with fewer than 4 valves. However, without a genetic match, the presumptive vertebrate host remains unknown.

Myxobolus goensisn. sp. (Myxozoa, Myxosporea, Myxobolidae), a parasite of the gills ofMugil cephalus(Osteichthyes, Mugilidae) from Goa, India

Two species of Myxobolus are reported from the gills of Mugil cephalus collected at Goa, India: M. goensis n. sp. and M. parvus Shulman, 1962. Myxobolus goensis n. sp. forms digitiform or rounded plasmodia between the gill rakers. Their spores are oval in frontal view, with tapered anterior extremity, and lemon-shaped in lateral view, measuring 9.7 (9.5-10.5) microm in length, 6.6 (6-7.5) microm in width, and 5.2 (5-6) microm in thickness. The polar capsules are pyriform and unequal in size. The larger ones are 5.3 (4.5-6) microm long and 2.4 (2-3) microm wide; the smaller ones are 2.4 (2-3) microm long and 1.8 (1.5-2) microm wide. The polar filament forms five turns aligned perpendicularly to the longitudinal axis of the larger polar capsules. Within the smaller polar capsules the polar filament is difficult to observe and, apparently, forms three coils. The spores are distinctly different from other Myxobolus species infecting M. cephalus and other Mugil spp. Furthermore, the present material is also different from 204 Myxobolus species presenting differently sized polar capsules, representing nearly all the known species with this characteristic. The fact that only the M. cephalus specimens were infected among a sample of 206 fish specimens, comprising 27 different species, strongly suggests that this parasite is specific to M. cephalus.

An image analysis algorithm for malaria parasite stage classification and viability quantification

With more than 40% of the world’s population at risk, 200–300 million infections each year, and an estimated 1.2 million deaths annually, malaria remains one of the most important public health problems of mankind today. With the propensity of malaria parasites to rapidly develop resistance to newly developed therapies, and the recent failures of artemisinin-based drugs in Southeast Asia, there is an urgent need for new antimalarial compounds with novel mechanisms of action to be developed against multidrug resistant malaria. We present here a novel image analysis algorithm for the quantitative detection and classification of Plasmodium lifecycle stages in culture as well as discriminating between viable and dead parasites in drug-treated samples. This new algorithm reliably estimates the number of red blood cells (isolated or clustered) per fluorescence image field, and accurately identifies parasitized erythrocytes on the basis of high intensity DAPI-stained parasite nuclei spots and Mitotracker-stained mitochondrial in viable parasites. We validated the performance of the algorithm by manual counting of the infected and non-infected red blood cells in multiple image fields, and the quantitative analyses of the different parasite stages (early rings, rings, trophozoites, schizonts) at various time-point post-merozoite invasion, in tightly synchronized cultures. Additionally, the developed algorithm provided parasitological effective concentration 50 (EC50) values for both chloroquine and artemisinin, that were similar to known growth inhibitory EC50 values for these compounds as determined using conventional SYBR Green I and lactate dehydrogenase-based assays.

Brain infecting kudoids of Australia's coral reefs, including a description of Kudoa lemniscati n. sp. (Myxosporea: Kudoidae) from Lutjanus lemniscatus (Perciformes: Lutjanidae) off Ningaloo Reef, Western Australia

A survey of the myxosporean fauna of Australian marine fishes revealed the presence of a number of putative species of Kudoidae (Multivalvulida) forming pseudocysts between the outer meningeal layer and the outer surface of the brains of the lutjanids Caesio cuning, Lutjanus carponotatus, Lutjanus ehrenbergii and Lutjanus fulviflamma and the mugilid Liza vaigiensis from Lizard Island on the Great Barrier Reef, Australia and Lutjanus lemniscatus off Ningaloo Reef, Western Australia. Morphometric data combined with Bayesian inference and maximum likelihood analyses of small subunit (SSU) and large subunit (LSU) ribosomal DNA (rDNA) was used for species identification and to explore relationships among these taxa. The brain-infecting taxa examined here formed a well-supported clade to the exclusion of non-brain infecting species in the phylogenetic analyses. The combined diagnostic approach identified an undescribed taxon, Kudoa lemniscati n. sp., from the brain of L. lemniscatus (Perciformes: Lutjanidae) off Ningaloo Reef, Western Australia, which we describe and characterise here. K. lemniscati n. sp. can be distinguished from all other species of Kudoa based on the combination of the distinct tropism for forming pseudocysts in the brain tissue, spores with 7 or 8 equal shell valves and 7 or 8 polar capsules, spore size and the differences in the SSU and LSU rDNA sequence data relative to other kudoids. Kudoa chaetodoni was found in the lutjanids C. cuning and L. carponotatus, expanding the known host range for this species to include chaetodontids and lutjanids. L. ehrenbergii and L. fulviflamma were infected with Kudoa lethrini off Lizard Island, a parasite previously known only from lethrinids. Specimens putatively identified as Kudoa yasunagai from Liza vaigiensis and Lutjanus ehrenbergii were morphologically similar and genetically identical over the SSU rDNA dataset to previously reported specimens, but differed by 4 to 11 nucleotides over the LSU dataset from the remaining isolates examined here. While these data are not definitive, they suggest the presence of a K. yasunagai complex.

Henneguya torpedo sp. nov. (Myxozoa), a parasite from the nervous system of the Amazonian teleost Brachyhypopomus pinnicaudatus (Hypopomidae)

A new species of Myxosporea, Henneguya torpedo sp. nov., is described from the brain and spinal cord of the Amazonian teleostean fish Brachyhypopomus pinnicaudatus collected from the Peixe Boi River, State of Park, Brazil. The spores were surrounded by a thick hyaline sheath that is homogeneous and electron translucent and consists of 2 layers of different densities. The total spore length is 48.62 +/- 0.51 microm (mean +/- SE), the ellipsoidal spore body length is 28.53 +/- 0.36 microm, the body width is 7.25 +/- 0.31 microm and the body thickness is 3.06 +/- 0.26 microm. Each of the 2 equal-sized valves presented a tapering tail (19.64 +/- 0.44 microm in length). The 2 equal-sized thin and smooth valves surrounded 2 equal-sized and elongated ellipsoidal polar capsules (6.41 +/- 0.26 x 1.84 +/- 0.19 microm) that contained 5 to 6 (rarely 7) polar filament coils. The binucleated sporoplasm contained numerous spherical sporoplasmosomes (-260 x -280 nm) with a laterally eccentric-dense structure containing a half-crescent section. The sporoplasmosomes are surrounded by a hyaline homogenous sheath. Based on the data obtained by light and electron microscopy and on the host specificity, the spores differed from the previously described Henneguya spp., mainly in the presence of a sheath surrounding the spores, the spore shape and size and the number and arrangement of the polar filament coils. Therefore, from this description we propose the establishment of a new species, which we have named Henneguya torpedo sp. nov.

[Use of the OTE-staining method for ultrathin sections on the example of microsporidia (Protozoa: Microsporidia)]

A novel method for staining ultrathin sections and examining organelles of taxonomic importance in microsporidian parasites was evaluated using oolong tea extract (OTE) and compared with traditional staining with uranyl acetate (UA). All basic intracellular structures of taxonomic significance were effectively stained with the OTE-staining method and additional layers of the polar filament with more clear boundaries between them were revealed. However, greater resolution and higher general contrast of several structures including membranes, layers of the envelope of mature spores, the structure of rough endoplasmic reticulum, Golgi complex, and nuclear chromatin were achieved with traditional UA-staining. The OTE-staining method has the advantage of being safe and preparations can be stored in light at room temperature with no loss in staining properties. However, greater staining time is required. We conclude that the OTE-staining method may be used as an alternative to traditional staining with UA with successful results.

SPORE ORNAMENTATION OF HAPLOSPORIDIUM NELSONI AND HAPLOSPORIDIUM COSTALE (HAPLOSPORIDIA), AND INCONGRUENCE OF MOLECULAR PHYLOGENY AND SPORE ORNAMENTATION IN THE HAPLOSPORIDIA

Spore ornamentation of Haplosporidium nelsoni and Haplosporidium costale was determined by scanning electron microscopy. For H. nelsoni, the spore surface was covered with individual ribbons that were tightly bound together and occurred as a single sheet. In some spores, this layer was overlaid with a network of branching fibers, about 0.05 microm in diameter, which often was dislodged from the spore at the aboral pole. For H. costale, ornamentation consisted of a sparse network of branching fibers on the spore surface. Molecular phylogenetic analysis of the phylum Haplosporidia revealed that Urosporidium, Bonamia, and Minchinia were monophyletic but that Haplosporidium was paraphyletic. All species of Minchinia have ornamentation composed of epispore cytoplasm, supporting the monophyly of this genus. The presence of spores with a hinged operculum and spore wall-derived ornamentation in Bonamia perspora confounds the distinction between Bonamia and Haplosporidium. Species with ornamentation composed of outer spore wall material and attached to the spore wall do not form a monophyletic group in the molecular phylogenetic analysis. These results suggest that the widely accepted practice of assigning all species with spore wall-derived ornamentation to Haplospordium cannot be supported and that additional genera are needed in which to place some species presently assigned to Haplosporidium.

Morphological and genetic differences among actinosporean stages of fish-parasitic myxosporeans (Myxozoa): difficulties of species identification

The occurrence and morphology of actinosporean stages of myxosporeans were studied at a fish farm and in the River Tisza in Hungary. The 43 samples sequenced belonged to 10 'genotypes', from which six were determined as new actinosporean types. Based on DNA sequence analysis, the assumed actinosporean developmental stages of four myxozoan species were identified. The raabeia type collected from the worm Branchiura sowerbyi was identified as Myxobolus cultus Yokoyama, Ogawa & Wakabyashi, 1995. This was the first occurrence of this parasite in Hungary. Aurantiactinomyxon type 'A' was assigned as a developmental stage of Thelohanellus hovorkai Achmerov, 1964, triactinomyxon type 'D' was identified as Myxobolus sp. from the fins of roach Rutilus rutilus, while the DNA sequence of the guyenotia type actinosporean was 99.9-100% identical with Sphaerospora sp. from the kidney tubules of goldfish Carassius auratus auratus. Partial 18S rDNA sequences of the myxosporeans Thelohanellus hovorkai, T. nikolskii Achmerov, 1955 and Myxobolus sp. from Rutilus rutilus were new additions to GenBank. The DNA sequence analysis revealed that, in the case of actinosporeans, different 'morphotypes' can belong to the same 'genotype'. This study confirmed that actinospore classification based solely on traditional morphological features may lead to false conclusions, thus sequence analysis of the 18S rDNA and/or other genes is recommended in species and type descriptions.

Effects of fixation, dehydration and staining on dimensions of myxosporidan

The effects of fixation, dehydration and staining on the morphological dimensions of myxo- and microsporidan spores were tested. Seven fixatives, two dehydrants and five stains were tested. Ten % formalin produced the least shrinkage and provided the best cytological detail of fixed material in both types of spores. All fixatives caused shrinkage of myxosporidan spore length and polar capsule length. Spore capsule width and polar capsule width were unaffected by 10% formalin. Ethyl alcohol caused no significant change in spore width. Microsporidan spore length shrunk with all fixatives, but spore width was generally unaffected. Dehydration, with either isopropyl alcohol or acetone, produced additional, significant shrinkage. The influence of stains on spore size was negligible. Heidenhains iron hematoxylin followed by eosin, and Mallory's analine-blue collagen stain, effectively stained myxo- and microsporidan spores.

Myxozoan parasites disseminated via oligochaete worms as live food for aquarium fishes: descriptions of aurantiactinomyxon and raabeia actinospore types

A total of 7 samples of live freshwater oligochaetes (mixed species), sold as 'tubifex' worms as food for aquarium fishes, were purchased over a 1 yr period from several pet shops in Munich, Germany, and screened for parasitic infections of myxozoans. The water associated with 5 samples contained actinospores at the time of purchase; 6 samples subsequently released spores in the laboratory. In all, 12 types of actinospores (Myxozoa: Myxosporea) from 4 collective groups were released by the oligochaetes. In the current study we provide descriptions of 2 aurantiactinomyxons (Myxobolus intimus Zaika, 1965 and type 1 nov.) and 3 raabeias (type 1 and 2 nov., Raabeia type 1 of Oumouna et al., 2003); descriptions of the 5 triactinomyxon and 2 hexactinomyxon types have been published previously. We include both raabeia and echinactinomyxon types in differential diagnoses of our raabeia forms because a clear distinction between these groups no longer exists in the literature. Comparison of 18S rDNA sequence data revealed that 1 of the novel aurantiactinomyxons was Myxobolus intimus. The sale of worms hundreds of km away from their point of origin is a means of dissemination of myxozoan parasites.

Kudoa alliaria in flesh of Argentinian hoki Macruronus magellanicus (Gadiformes; Merlucciidae)

Myxozoans of the genus Kudoa are widespread parasites of marine fishes and primarily infect the body musculature of their hosts. Although Kudoa species are not usually associated with host mortality, some do form macroscopic cysts in the tissue and some are associated with post mortem tissue degradation. This is of concern to commercial fisheries as fillets may be unmarketable due to these infections. Because different species of Kudoa have different effects on their hosts, it is important to correctly identify species with epidemiological relevance, distinguishing those that are benign from those that are associated with these detrimental effects. Using morphological and molecular analyses, we identified K. alliaria infecting Argentinian hoki Macruronus magellanicus. Comparisons of the small subunit ribosomal DNA sequence revealed that K. alliaria is genetically very similar to K. rosenbuschi. Furthermore, there is significant overlap in myxospore dimensions between descriptions of these 2 Kudoa species as well as those of other Patagonian fishes. Thus, without careful examination of the myxospore dimensions, it may be difficult to identify these species on a routine basis. It is critical to accurately identify K. alliaria as, unlike K. rosenbuschi, it is not associated with tissue degradation. Ambiguities in some species descriptions highlight the need for thorough morphological analyses accompanied by molecular comparisons to clarify the species boundaries between Kudoa parasites of Patagonian fishes.

A NEW MYXOZOAN FROM FERAL GOLDFISH (CARASSIUS AURATUS)

In February 2004, a mass die-off of common goldfish Carassius auratus L., presumptively caused by bacterial coldwater disease (Flavobacterium psychrophilum), occurred at Fern Ridge Reservoir, Oregon. A range of size classes was affected, but all mature fish were female and all fish were infected with a single myxozoan, Chloromyxum auratum n. sp. No histological changes were observed associated with the parasite. Infection was represented by mictosporic plasmodia and free-floating spores in the gall bladder. Parasite spores were nearly spherical, 13.6 microm long x 12.6 microm wide x 13.1 microm thick, and possessed 4 equal-sized polar capsules. Spores had a coglike appearance in apical view because of distinct ridges 2.1 microm high protruding from the valve cells. There were 6-9 extrasutural ridges per valve (15-20 ridges per spore), aligned along the longitudinal axis, with some branching, and convergence at both poles. Morphologically, spores identified most closely with Chloromyxum cristatum Léger, 1906; however, 18S rDNA sequence data indicated only 97.5% similarity over 2,076 bp with Chloromyxum cyprini, the only synonym of C. cristatum for which DNA data are available; additional sequence data may reveal the other synonyms to be distinct species. This is the first record of a species of Chloromyxum from goldfish.

Myxobolus insignis sp. n. (Myxozoa, Myxosporea, Myxobolidae), a parasite of the Amazonian teleost fish Semaprochilodus insignis (Osteichthyes, Prochilodontidae)

A new myxosporean species is described from the fish Semaprochilodus insignis captured from the Amazon River, near Manaus. Myxobolus insignis sp. n. was located in the gills of the host forming plasmodia inside the secondary gill lamellae. The spores had a thick wall (1.5-2 microm) all around their body, and the valves were symmetrical and smooth. The spores were a little longer than wide, with rounded extremities, in frontal view, and oval in lateral view. They were 14.5 (14-15) microm long by 11.3 (11-12) microm wide and 7.8 (7-8) microm thick. Some spores showed the presence of a triangular thickening of the internal face of the wall near the posterior end of the polar capsules. This thickening could occur in one of the sides of the spore or in both sides. The polar capsules were large and equal in size surpassing the midlength of the spore. They were oval with the posterior extremity rounded, and converging anteriorly with tapered ends. They were 7.6 (7-8) microm long by 4.2 (3-5) microm wide, and the polar filament formed 6 coils slightly obliquely to the axis of the polar capsule. An intercapsular appendix was present. There was no mucous envelope or distinct iodinophilous vacuole.

Morphological and molecular comparison of Myxobolus procerus (Kudo, 1934) and M. intramusculi n. sp. (Myxozoa) parasitising muscles of the trout-perch Percopsis omiscomaycus

Inter- and intracellular cysts from a presumed single species, Myxobolus procerus (Kudo, 1934), parasitising the trout-perch Percopsis omiscomaycus were compared with respect to their spore morphology and small subunit 18S ribosomal DNA. The two cyst types have similar pyriform spores and comparable ranges in spore length and width, size of the polar capsules and number of filament coils. However, fixed spores of the intracellular cysts are significantly shorter (p<0.05) in mean length than those from intercellular cysts, giving them a broader appearance. Comparing 991 base pairs of 18S rDNA revealed a 20 bp difference between the two cyst types (97.9% similarity), 10 due to base substitutions and 10 due to the presence or absence of a base. The described morphological differences and consistent 2.1% difference in the 18S rDNA reveal that the intracellular form is a separate species, which is described herein as Myxobolus intramusculi n. sp. M. intramusculi n. sp. and M. procerus may be sister species and it is suggested that the two species arose through sympatric speciation involving a switch in site specificity within a single host species.

SPECIES COMPOSITION OF ASSEMBLAGES OF CERATOMYXA (MYXOZOA), PARASITES OF LINGS GENYPTERUS (OPHIDIIDAE) IN THE SOUTHEASTERN PACIFIC OCEAN: AN ECOMORPHOMETRIC APPROACH

Studies on Myxozoa have emphasized their potential impact on aquatic animal health but less on ecological aspects. In this investigation, we assess the importance of host and latitudinal variations in the morphometry of spores of Ceratomyxa Théohan, 1892 (Myxozoa) from the gall bladder of 3 ling Genypterus (Pisces; Ophidiidae) species. Discriminant analyses indicated that several morphospecies of Ceratomyxa coexist in these hosts, despite the fact that the specific level of taxonomic resolution of each spore was not attempted. At least 4 species, i.e., Ceratomyxa hokarari Meglitsch, 1960; Ceratomyxa inversa Meglitsch, 1960; Ceratomyxa laxa Meglitsch, 1960; and Ceratomyxa elongata Meglitsch, 1960 occur in the study area, and at least 2 species co-occur in each host and geographical location. The most widespread pattern found is that spores are larger in golden ling (Genypterus blacodes) and spore size decreases with increasing latitude; this may be associated with the species composition of these assemblages, as well as with the habitat and diet segregation of the host species.

Henneguya schizodon n. sp. (Myxozoa, Myxobolidae), a parasite of the Amazonian teleost fish Schizodon fasciatus (Characiformes, Anostomidae)

A new histozoic species of myxosporean (Henneguya schizodon n. sp.) is described from the Amazon River teleost fish Schizodon fasciatus Spix & Agassiz, 1892 (Characiformes, Anostomidae). The plasmodia, which showed asynchronous development, were located in the kidney of the host. The spore body was ellipsoidal and was 13.1 (12-14) micron long by 3.3 (3-4) micron wide. The total length of the spore was 28.9 (27-30) micron, and each value had a caudal process measuring 16.3 (15-17) micron. The polar capsules were 5.4 (5-6) micron long by 1.3 (1-1.5) micron wide, and each had a polar filament with 8-10 coils. The characteristics of the species were compared with nearly all the species described so far, including all the species reported from South American fishes. This comparison allows to consider the materials as a new species, and the name Henneguya schizodon n. sp. is proposed.

Spore morphotypes of Thelohania solenopsae (microsporidia) described microscopically and confirmed by PCR of individual spores microdissected from smears by position ablative laser microbeam microscopy

Development of Thelohania solenopsae, a parasite of the red imported fire ant (Solenopsis invicta), until recently was thought to include formation of two types of spores: unicellular meiospores, maturing inside sporophorous vesicles in sets of eight (octospores); and Nosema-like binuclear free spores. Megaspores, discovered in 2001, develop primarily in alates and are morphologically distinct from the two previously known types of spores. The role of megaspores in the T. solenopsae life cycle, as well as their existence, has been questioned. The current research includes light and electron microscopic descriptions of the three major spore morphotypes characteristic of T. solenopsae development. In addition, individual octospores and megaspores were isolated into groups of 8–20 from methanol-fixed and Calcofluor-stained smears of the infected ants for subsequent PCR analysis by the laser pressure catapulting function of a position ablative laser microbeam microscope, a technique applied for the first time to research of microsporidia. The PCR-amplified SSU rDNA nucleotide sequences from octospores and megaspores were identical. This, along with the consistency with which megaspores are detected in infected ants, demonstrates that megaspores are integral to the life cycle of T. solenopsae.

Analysis of four human microsporidian isolates by MALDI-TOF mass spectrometry

Spores of four species of microsporidia isolated from humans were analyzed by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) and specific biomarkers were found for each. The microsporidia analyzed included three species, Encephalitozoon cuniculi, Encephalitozoon hellem, and Encephalitozoon intestinalis and the fourth organism is the recently described Brachiola algerae. Whole spores, spore shells, and soluble fractions were applied directly to the MALDI target without further purification steps. MALDI-TOF MS analysis of both whole spores and soluble fractions of the four isolates revealed a group of unique, characteristic, and reproducible spectral markers in the mass range of 2,000-8,000 Da. Statistical analysis of the averaged centroided masses uncovered two distinct sets of unique peptides or biomarkers, one originated from whole spores and the other from soluble fractions, that can differentiate the four microsporidian species studied. MALDI-TOF MS analysis of whole organisms is a rapid, sensitive, and specific option to characterize microsporidian isolates and has the potential for several applications in parasitology.

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 eastern Europe. Analysis of the screened samples by polymerase chain reaction and comparison of morphological data indicated that these actinospores did not correspond to the triactinospore of Myxobolus cerebralis. Although identification of these triactinomyxon types was beyond the scope of this study, these data suggest that the unregulated import-export and exchange of live organisms for ornamental fish food may result in accidental introduction or dissemination of myxozoan parasites.