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Trypanosomatid protozoa in plants of southeastern Spain: characterization by analysis of isoenzymes, kinetoplast DNA, and metabolic behavior.

Three flagellates of the family Trypanosomatidae were isolated from mango fruits (Mangifera indica) and from the stems of clover (Trifolium glomeratum) and Amaranth (Amaranthus retroflexus) in southeastern Spain and were adapted to in vitro culture in monophase media. The parasites showed an ultrastructural pattern similar to that of other species of the genus Phytomonas. Mango and clover isolates differed from amaranth isolates in ultrastructural terms. The isolates were characterized by isoenzymatic analysis and by kDNA analysis using five different restriction endonucleases. With eight of the nine enzymatic systems, mango and clover isolates were distinguished from those of amaranth. Nevertheless, with the enzymes malate dehydrogenase and superoxide dismutase, flagellates isolated from clover were differentiated from those isolated from mango. Electrophoretic and restriction-endonuclease analysis of kDNA minicircles showed similar restriction cleavage patterns for the isolates from mango and clover, whereas the patterns of the amaranth isolates differed. The results of the present study confirm that the strains isolated from mango and clover constitute a phylogenetically closely related group of plant trypanosomatids, which is more distantly related to the strain isolated from amaranth. The similarities in the results obtained for isolates from mango and clover foliage, on the one hand, and those obtained from tomato and cherimoya fruits (studied previously), on the other, as well as the geographic proximity of the different plants support the contention that only one strain is involved, albeit one strain that can parasitize different plants. Furthermore, some of the plants appear to act as reservoirs for the parasites. On the other hand, the metabolism studies using [1H]-nuclear magnetic resonance spectroscopy did not reveal that the catabolism of Phytomonas in general follows a pattern common to all the species or isolates. Phytomonas are incapable of completely degrading glucose, excreting a large part of their carbon skeleton into the medium as fermentative metabolites (acetate, ethanol, glycine, glycerol, and succinate).

Animals↗

Vertical niche separation of two consumers (Rotatoria) in an extreme habitat.

Herbivore populations are commonly restricted by resource limitation, by predation or a combination of the two. Food supplement experiments are suitable for investigating the extent of food limitation at any given time. The main part of this study was performed in an extremely acidic lake (pH 2.7) where the food web consists of only a few components and potential food sources for herbivores are restricted to two flagellates. Life table experiments proved that Chlamydomonas was a suitable food source whereas Ochromonas was an unsuitable food source. The two flagellates and the two rotifers exhibit a pronounced vertical distribution pattern. In this study, a series of food supplement experiments were performed in order to: (1) quantify and compare potential resource limitation of two primary consumers (Cephalodella hoodiand Elosa worallii, Rotatoria) over time, (2) compare their response at different temperatures, (3) evaluate the effect of having an unsuitable food source alongside a valuable one, (4) estimate the effect of predation on rotifers by Heliozoa, and (5) compare the results with those from other acidic lakes. Additionally, the spatio-temporal population dynamics of both species were observed. The field data confirmed a vertical separation of the two species with E. worallii dominating in the upper water layers, and C. hoodi in the deeper, cooler water layers. The results from the food supplement experiments in which Chlamydomonas served as the supplemented suitable food source showed that the two rotifers were food limited in the epilimnion throughout the season to different extents, with Cephalodella being more severely food limited than Elosa. The experiments at different temperatures provided evidence that Elosa had a higher optimum temperature for growth than Cephalodella. When the unsuitable food algae Ochromonas was added alongside the suitable food source Chlamydomonas, C. hoodi was unaffected but E. worallii was negatively affected. Predation of Heliozoa on rotifers was observed but the total effect on the rotifer dynamics is probably low. The comparison with other lakes showed that resource limitation also occurred in one other lake, although to a lesser extent. Overall, the vertical separation of the two rotifers could be explained by both their differential extent of resource limitation and differential response to temperature.

Animal Nutritional Physiological Phenomena↗

Control of microbial communities by the macrofauna: a sensitive interaction in the context of extreme summer temperatures?

Climate models predict an increasing frequency of extremely hot summer events in the northern hemisphere for the near future. We hypothesised that microbial grazing by the metazoan macrofauna is an interaction that becomes unbalanced at high temperatures due to the different development of the grazing rates of the metazoans and the growth rates of the microbial community with increasing temperature. In order to test this hypothesis, we performed grazing experiments in which we measured the impact of increasing temperatures on the development of the grazing rates of riverine mussels in relation to the growth rates of a unicellular prey community (a natural heterotrophic flagellate community from a large river). In a first experimental series using Corbicula fluminea as a grazer and under the addition of a carbon source (yeast extract), the increase of the prey's growth rates was considerably stronger than that of the predator's grazing rates when temperatures were increased from 19 to over 25 degrees C. This was also the outcome when the mussels had been acclimatized to warm temperatures. Hereafter, specific experiments with natural river water at temperatures of 25 and 30 degrees C were performed. Again, a strong decrease of the mussels' grazing rates in relation to the flagellate growth rates with increasing temperature occurred for two mussel species (C. fluminea and Dreissena polymorpha). When performing the same experiment using a benthic microbial predator community (biofilms dominated by ciliates) instead of the benthic mussels, an increase of the grazing rates relative to the growth rates with temperature could be observed. Our data suggest that predator-prey interactions (between metazoans and microbes) that are balanced at moderate temperatures could become unbalanced at high temperatures. This could have significant effects on the structure and function of microbial communities in light of the predicted increasing frequency of summer heat waves.

Animals↗

Structural and immunocytochemical characterization of the Ginkgo biloba L. sperm motility apparatus.

Ginkgo biloba and the cycads are the only extant seed plants with motile sperm cells. However, there has been no immunocytochemical characterization of these gametes to determine if they share characteristics with the flagellated sperm found in bryophytes and pteridophytes or might give clues as to the relationships to nonflagellated sperm in all other seed plants. To determine characteristics of proteins associated with the motility apparatus in these motile sperm, we probed thin sections of developing spermatogenous cells of Ginkgo biloba with antibodies to acetylated and tyrosinated tubulin and monoclonal antibodies that recognize mammalian centrosomes and centrin. The blepharoplast that occurs as a precursor to the motility apparatus consists of an amorphous core, pitted with cavities containing microtubules and a surface studded with probasal bodies. The probasal bodies and microtubules within the blepharoplast cavities are labeled with antibodies specific to acetylated tubulin. Positive but weak reactions of the blepharoplast core occur with the centrosomereactive antibodies MPM-2 and C-9. Reactions to centrin antibodies are negative at this developmental stage. From this pre-motility apparatus structure, an assemblage of about 1,000 flagella and associated structures arises as the precursor to the motility apparatus for the sperm. The flagellar apparatus consists of a three-layered multilayered structure that subtends a layer of spline microtubules, a zone of amorphous material similar to that in the blepharoplast, and the flagellar band. Centrin antibodies react strongly with the multilayered structure, the transition zone of the flagella, and fibrillar material near the flagellar base at the surface of the amorphous material. Both the spline microtubules and all of the tubules in the flagella react strongly with the antibodies to acetylated tubulin. These localizations are consistent with the localizations of these components in pteridophyte and bryophyte spermatogenous cells, although the blepharoplast material surrounding and connecting flagellar bases does not occur in the seedless (nonseed) land plants. These data indicate that despite the large size of ginkgo gametes and the taxonomic separation between pteridophytes and Ginkgo biloba, similar proteins in gametes of both groups perform similar functions and are therefore homologous among these plants. Moreover, the presence of acetylated tubulin in bands of microtubules may be a characteristic shared with more derived non-flagellated sperm of other conifers and angiosperms.

Cell Movement↗

Rapid isolation of metacyclic trypomastigotes of Trypanosoma cruzi from feces and urine of the vector.

Metacyclic trypomastigotes of Trypanosoma cruzi from infected Triatoma infestans were isolated and purified by an improved procedure. By using feces and urine of bugs the duration and the number of steps for purification were greatly reduced, thereby minimizing any possible effects on the flagellates. After DEAE-Sephacel column chromatography, a buffer supplemented with bovine serum albumin protected against the slight surface alterations of the trypomastigotes otherwise observed. About 10(7) metacyclic trypomastigotes (including 30% intermediate flagellates) were obtained from 100 bugs. The intermediate forms possessed the surface charge of trypomastigotes, and the kinetoplast was beside or posterior to the nucleus but not subterminal. Further increases in the number of bugs and the purified trypomastigotes were also possible with only slight increases in the time needed for isolation. In a comparison of complement-mediated lysis resistance and infectivity for mice, pre- and post-separation trypomastigotes showed no significant differences.

Animals↗

A comparison of selected immunological techniques used to detect anti-leishmanial antibodies in the sera of two reptile species.

European green lizards (Lacerta viridis) and spiny-tailed agamids (Agama caudospinosum) were obtained from areas endemic for human leishmaniasis. Serum antibody titres against Leishmania agamae, a reptilian leishmanial species, in normal lizards and lizards injected with Leishmania agamae promastigotes were measured by 5 immunological methods commonly used in the serodiagnosis of the human and mammalian leishmaniasis viz. immobilisation test (IMM), direct agglutination (DA), complement-fixation test (CFT), indirect haemagglutination (IHA) and enzyme-linked immunosorbent assay (ELISA). Correlation coefficients (r) were determined for comparisons between each method and linear regression equations calculated to convert antibody titres by one method to those by another. In each lizard species, the IMM test gave the lowest values while the highest were obtained with ELISA. The highest mean titre obtained by ELISA was between 2 and 10 times that obtained by the other methods for both control and immune sera. The methods of preparing the leishmanial antigen extracts affected the IHA and ELISA titres, while the source of complement was critical in obtaining good CFT values. Correlations ranging from 3% to 77% were found for the control animals but higher values ranging from 65% to 96% were obtained with the immunised lizards. Overall, the best correlation was with IHA and ELISA (r greater than 0.82) and with ELISA values for different antigen preparations compared with each other for both control (r greater than 0.67) and immune (r greater than 0.90) sera. ELISA thus appears the most sensitive method for detection and quantitation of anti-flagellate antibodies in normal lizard serum and for the determination of titres in immune serum. ELISA is the most applicable technique for screening reptiles and other lower vertebrates for anti-parasite immunoglobulins, and for screening potential carriers or reservoirs of infective flagellates in epidemiological studies aimed at disease control, especially in areas where human infections are prevalent.

Agglutination Tests↗

The use of DNA hybridization for the detection of Leishmania aethiopica in naturally infected sandfly vectors.

Hybridization with kinetoplast deoxyribonucleic acid (kDNA) probes was used to detect Leishmania aethiopica in naturally infected sandflies in south-west Ethiopia, an endemic area for cutaneous leishmaniasis. 396 sandflies were dissected; microscopy revealed flagellates in the midgut of 5 Phlebotomus pedifer. The infecting flagellates were confirmed as L. aethiopica by isoenzyme typing. Gut specimens for all dissected sandflies were hybridized with total L. aethiopica kDNA as well as with a cloned kDNA probe specific for L. aethiopica. Samples from sandflies which were found to be infected microscopically also hybridized with the L. aethiopica kDNA probes. One additional sandfly hybridized but was not shown to be infected by microscopical examination. Hybridization experiments with 65 whole squash-blotted sandflies gave results that correlated very well with results obtained using microscopy. Our results indicate that DNA probing is a useful method to detect Leishmania infection in sandfly midguts as well as in whole squash-blotted sandflies, and can be used to follow changes of infection rate. DNA probing is therefore an alternative to microscopy in large-scale epidemiological studies as well as monitoring control programmes aimed at human leishmaniasis.

Animals↗

Phylogenetic position of the genus Perkinsus (Protista, Apicomplexa) based on small subunit ribosomal RNA.

Parasites of the genus Perkinsus destroy marine molluscs worldwide. Their phylogenetic position within the kingdom Protista is controversial. Nucleotide sequence data (1792 bp) from the small subunit rRNA gene of Perkinsus sp. from Anadara trapezia (Mollusca: Bivalvia) from Moreton Bay, Queensland, was used to examine the phylogenetic affinities of this enigmatic genus. These data were aligned with nucleotide sequences from 6 apicomplexans, 3 ciliates, 3 flagellates, a dinoflagellate, 3 fungi, maize and human. Phylogenetic trees were constructed after analysis with maximum parsimony and distance matrix methods. Our analyses indicate that Perkinsus is phylogenetically closer to dinoflagellates and to coccidean and piroplasm apicomplexans than to fungi or flagellates.

Animals↗

Scaling of energy metabolism in unicellular organisms: a re-analysis.

The database used by Hemmingsen (1960) to compute energy metabolism in unicellular organisms was reassembled and submitted to linear (log-log) analysis. As Hemmingsen noted, this data set includes marine zygotes, which are not unicellular organisms. If no temperature correction factors are applied to the data the best-fit regression line has a slope of 0.698 +/- 0.024. Application of the temperature correction factors assumed to have been used by Hemmingsen gave a slope of 0.756 +/- 0.021, identical to the value he reported. The correlation coefficient is 0.97. The mean scatter about the regression line exceeds 100%. A revised set of temperature correction factors gave a slope of 0.730 +/- 0.021, suggesting that the value of almost exactly three-quarters obtained by Hemmingsen was probably fortuitous. The slope of the best-fit regression line is very sensitive to the inclusion of bacteria and flagellates. When the data points for these organisms are omitted from the calculation the slope decreases to 0.645 +/- 0.045. When the data points for bacteria, flagellates and marine zygotes are omitted, the slope drops to 0.608 +/- 0.025. The correlation coefficient (0.97), compared to the best-fit line reported by Hemmingsen, is unaffected; the mean deviation about the regression line drops to 40% and the points are evenly distributed about the regression line. Because of the small number of species for which measurements have been made, the existing database relating energy metabolism to cell size is not representative of unicellular organisms generally. It is concluded that the case for a three-quarters power rule expressing energy metabolism as a function of size in unicellular organisms generally is not at all persuasive.

Animals↗

Primitive mitotic mechanisms.

Unorthodox mitotic mechanisms are reviewed and their contribution to the understanding of evolution of the orthodox mitotic apparatus is considered. Dinoflagellates and hypermastigote flagellates are of particular significance because the microtubular mitotic apparatus is entirely extranuclear with the nuclear membrane persisting through mitosis. Chromosomes are attached to the nuclear membrane. In hypermastigole flagellates early kinetochore separation is on the nuclear membrane without any contribution from microtubules. In dinoflagellates the chromosomes are also attached to the nuclear membrane, but at least in some species cytoplasmic microtubules connect to the attachment site. In Syndinium the attachment site resembles a typical kinetochore, but is inserted in the nuclear membrane. A similar kinetochore is found in certain Radiolaria, but with an intranuclear spindle apparatus the association with the nuclear membrane is no longer necessary and has been lost. Mitosis in the yeast Saccharomyces is essentially orthodox, though chromosomes do not condense. No kinetochores are seen, but a single microtubule makes direct contact with the 20 nm chromatin fiber of each chromosome and shortens during anaphase. About 5-10 microtubules are continuous between the spindle pole bodies and form the elongating central spindle.

Biological Evolution↗

Protist kinetids: structural conservatism, kinetid structure, and ancestral states.

The protist kinetid is considered a conservative indicator of phylogenetic relationship. This conclusion is supported by the apparently inverse relationship between the conservation of structure and its level in the organizational hierarchy. A comparative examination of features of protist kinetids indicates that pattern is strongly conserved; within and among flagellate taxa there is more variability in pattern than within the ciliates. It is concluded that the ancestral flagellate kinetid is a pair of orthogonally oriented kinetosomes having one striated rootlet and at least one microtubular ribbon. The ancestral kinetid of the ciliates is also a dikinetid structure, though represented by a paired set of parallel kinetosomes, probably similar to that found today in karyorelictid ciliates, presumptive descendants of the ancestral stock.

Animals↗

The secondary structure of large-subunit rRNA divergent domains, a marker for protist evolution.

The secondary structure of the large-subunit ribosomal RNA (24-26S rRNA) has been studied with emphasis on comparative analysis of the folding patterns of the divergent domains in the available protist sequences, that is Prorocentrum micans (dinoflagellate), Saccharomyces carlsbergensis (yeast), Tetrahymena thermophila (ciliate), Physarum polycephalum and Dictyostelium discoideum (slime moulds), Crithidia fasciculata and Giardia lamblia (parasitic flagellates). The folding for the D3, D7a and D10 divergent domains has been refined and a consensus model for the protist 24-26S rRNA structure is proposed. Two hundred seventy-seven nucleotide-long aligned sequences representing all or part of the D3, H32-33, D8, D9 and D10 divergent domains are used for the construction of unrooted phylogenetic trees either calculated from a nucleotide difference matrix, or determined with the PAUP programme based on the parsimony method. Both phylogenies suggest three major branchings, the first leading to the dinoflagellate (which branches off first), ciliate and yeast, the second to the slime moulds, and the last to the parasitic flagellates.

Animals↗

Archamoebae: the ancestral eukaryotes?

The archezoan phylum Archamoebae Cavalier-Smith, 1983 is here modified by adding a new order Phreatamoebida (presently containing only Phreatamoeba) and removing the family Entamoebidae. Entamoebidae are instead tentatively placed as a class Entamoebea together with the classes Heterolobosea, Percolomonadea and Pseudociliatea in the new protozoan phylum Percolozoa Cavalier-Smith, 1991. Thus emended the phylum Archamoebae is more homogeneous; it is more distinguished from the other two phyla of the primitively amitochondrial kingdom and superkingdom Archezoa (i.e. Metamonada and Microsporidia) by having kinetids with only a single flagellum and basal body and a flagellar root consisting of a cone of evenly spaced microtubules. This unikont character of the archamoebae suggests that they may be ancestral to the tetrakont Metamonada, from which the non-flagellate Microsporidia possibly evolved. Higher eukaryotes (superkingdom Metakaryota) probably evolved from a tetrakont metamonad by the symbiotic origin of mitochondria and peroxisomes. If so, the Archamoebae are the most primitive extant phylum of eukaryotes; if molecular phylogenetic studies confirm this idea, Archamoebae will deserve intensive study, which could reveal much about the origin of the eukaryote condition and also establish what is truly universal among eukaryotes. Archamoebae, like other Archezoa, lack mitochondria and peroxisomes and have no obvious Golgi dictyosomes. Their evolutionary significance is discussed and a detailed classification is presented in which the two earlier classes are merged into a single one: Pelobiontea Page, 1976 stat. nov., containing two orders Mastigamoebida Frenzel, 1892 (Syn. Rhizo-Flagellata Kent, 1880 non Rhizomastigida auct.) (including Mastigamoeba, Mastigina, Mastigella, Pelomyxa and probably a few other genera, which have one or more flagella or cilia (motile or immotile, 9 + 2 or otherwise) in the amoeboid trophic phase), and Phreatamoebida ord. nov. (including only Phreatamoeba in the new family Phreatamoebidae, which has alternating phases of non-flagellate amoebae and uniflagellate cells). Mastigamoebida are divided into three families: Mastigamoebidae Goldschmidt, 1907; Mastigellidae fam. nov.; Pelomyxidae Schulze, 1877. Archamoebae may be uni- or multi-nucleate and either gut parasites or (more usually) free-living in soil, freshwater, or marine habitats. Some can form cysts that would probably fossilize; the earliest (1450 My old) smooth-walled fossil cells large enough to be probable eukaryotes might therefore be archamoebal cysts.

Amoeba↗

Somatic kinetics or paroral membrane: which came first in ciliate evolution?

The ciliate species which lack a distinctive oral ciliature are considered to represent an ancestral state in ciliate evolution. Consequently, the somatic kineties composed of kinetids (kinetosomes plus cilia and associated fibrillar systems) are thought to be the ancestral ciliature. Results on stomatogenesis in 'gymnostomial ciliates' have shown that these ciliates probably have evolved from ancestors already equipped with an oral ciliature. Thus instead of the somatic, the oral ciliature may be regarded an ancestral. Based on these ideas a hypothesis on the evolution of the ciliate kinetome (assembly of all kinetids covering the body of a given ciliate) is presented. The first step in the evolution of the kinetome was the formation of a paroral membrane, a compound ciliary organelle lying along the right side of the oral area which historically but falsely is termed membrane. It was composed of kinetosomal dyads (dikinetids), derived from the kinetid of a dinoflagellate-like ancestor. From the beginning the paroral membrane was responsible for locomotion, ingestion and for the formation of a cytopharyngeal tube which the first ciliate probably had inherited from its flagellate ancestor. In the second step a first somatic kinety was formed from the right row of kinetosomes of the paroral membrane as a result of a longitudinal splitting of the paroral membrane and a subsequent migration of the forming kinety to the right into the somatic cortex. To increase the number of somatic kineties this process was repeated until the kinety produced first reached the left border of the oral area. By this step the locomotive and the nutritional functions were differentiated between somatic and oral structures. In a third step the adoral organelles were formed from somatic kinetids left of the oral area. The primitive type of stomatogenesis was a buccokinetal one derived from the mode the flagellate ancestor used to distribute its replicated kinetosomes to the offspring cells (buccokinetal means that at least parts of the oral anlage for the posterior offspring cell has its origin in the parental oral apparatus). This hypothesis, based on comparative studies on ciliate morphogenesis, is corroborated by molecular data from other laboratories.

Animals↗

Opsonic activity of anti-flagellar serum against Clostridium chauvoei by mouse polymorphonuclear leucocytes.

The role of anti-flagellar serum against Clostridium chauvoei in phagocytosis by mouse polymorphonuclear leucocytes was examined. Anti-flagellar serum markedly increased phagocytic rate against the flagellated strain Okinawa but not against a non-flagellated mutant (NFM) derived from the same strain, while anti-NFM serum increased the phagocytic rate against both strains. These results indicate that anti-flagellar serum exerts its protective effect by opsonic activity.

Agglutination Tests↗

Effect of motility and chemotaxis on the invasion of Salmonella typhimurium into HeLa cells.

Salmonella typhimurium strain LT2 is able to invade HeLa cells in vitro. The effect of the motility and chemotaxis of the bacteria on cell invasion were examined by two methods: (1) conventional invasion assays where the HeLa cell monolayers were placed horizontally at the bottom of plastic wells and (2) vertical assays where the HeLa cell monolayer attached to one face of plastic bottles was placed vertically. In both assays, the invasion rate of the wild-type strain was higher than that in isogenic non-motile mutants. There was no significant difference between the invasion rate of non-flagellated mutants and that of a flagellated but non-motile mutant. These observations indicated that the motility per se increases the rate of the bacterial invasion by increasing the chance of encounter between Salmonella and the HeLa cells. Smooth-swimming non-chemotactic mutants exhibited 10 times higher invasion rates than the wild-type strain in conventional assays but their invasion rates in vertical assays were approximately equal to that of the wild-type strain. This result indicated that in the conventional assays, the migration of the wild-type bacteria towards the HeLa cells was hampered by their chemotactic responses. Tumbly non-chemotactic mutants exhibited invasion rates intermediate between the wild-type and non-motile strains presumably because of their intermediate net speeds of migration.

Cell Movement↗

NgUNC-119, Naegleria homologue of UNC-119, localizes to the flagellar rootlet.

The UNC-119 family of proteins is ubiquitous in animals. The expression of UNC-119 is prominent in neural tissues including photoreceptor cells. Homologues of UNC-119 are also found in ciliated (or flagellated) single-celled organisms; however, the cellular distribution of this protein in protists is unknown. We cloned and characterized a homologue of unc-119 from the ameboflagellate Naegleria gruberi (Ngunc-119) and identified the cellular distribution of the protein. The Ngunc-119 open reading frame contained 570 nucleotides encoding a protein of 189 amino acids with a predicted molecular weight of 22.1 kDa, which is similar to that of Paramecium UNC-119 and Trypanosoma UNC-119. These three proteins are 46-48% identical in their amino acid sequences. The smaller NgUNC-119 corresponds to the conserved C-terminal 3/4 of the UNC-119 from multi-cellular organisms. The amino acid sequence of NgUNC-119 is 43-50% identical to that of the conserved C-terminal regions. NgUNC-119 was not found in growing amoebae but accumulated rapidly after the initiation of differentiation into flagellates. Indirect immunofluorescence staining of differentiating N. gruberi showed that NgUNC-119 begins to concentrate at a spot near the nucleus of differentiating cells and then elongates into a filamentous structure. Purification and indirect immunofluorescence staining of the Naegleria flagellar rootlet suggested that NgUNC-119 is a component of the flagellar rootlet.

Amino Acid Sequence↗

Broad dissemination of Histomonas meleagridis determined by the detection of nucleic acid in different organs after experimental infection of turkeys and specified pathogen-free chickens using a mono-eukaryotic culture of the parasite.

Histomonas meleagridis, a flagellated protozoan parasite, is the causative agent of histomonosis (syn. histomoniasis, blackhead) in turkeys and chickens. The organs primarily affected by the parasite are the caeca and the liver. Until now, only few reports exist in which the parasite has been diagnosed in tissues other than those mentioned above. Hence, the aim of this study was to perform a systematic investigation of various organs of turkeys and specified pathogen-free chickens following an experimental infection with a mono-eukaryotic culture of Histomonas meleagridis in order to determine the dissemination of the flagellate in infected birds. Molecular methods like PCR and in situ hybridization were used for this purpose. For the first time, the DNA of the parasite could be detected in 13 different organs of infected turkeys by PCR including the proventriculus, duodenum, jejunum, caeca, pancreas, bursa of Fabricius, liver, kidney, spleen, heart, lung, thymus and the brain. Most of these findings were further confirmed by in situ hybridization. In contrast to the turkeys that all died shortly after the infection, all of the chickens survived without displaying any clinical symptoms. Even at necropsy, only mild pathological changes were observed in the caeca. Nevertheless, the parasite could also be detected in various organs of these birds, namely the caeca, bursa of Fabricius, kidney, heart and the brain.

Animals↗