Morphological and molecular identification of non-Tritrichomonas foetus trichomonad protozoa from the bovine preputial cavity

Tritrichomonas foetus is the causative agent of bovine trichomonosis. This protozoan is found in the preputial cavity of bulls and is transmitted to cows during coitus. Currently, the diagnosis of this parasite is based on microscopic examination of preputial washings or scrapings, but it was recently recognized that other trichomonads similar in size, shape, and motility to T. foetus can be present in preputial samples. Despite the serious consequences of an incorrect diagnosis for bovine trichomonosis, the precise speciation of these other trichomonads has remained uncertain. Here, a total of 12 non-T. foetus isolates were microscopically examined. On the basis of morphological criteria, seven of these isolates were identified as Tetratrichomonas sp., whereas four other isolates coincided with the description of Pentatrichomonas hominis. In the last isolate, a third non-T. foetus species was identified as belonging to the genera Pseudotrichomonas or Monocercomonas: the first time that species of either of these genera have been reported in preputial samples. To confirm these data, small subunit rRNA gene sequences were obtained by PCR from the 12 trichomonad isolates. These new sequences were analysed in a broad phylogeny including 72 other parabasalid sequences. From our phylogenetic trees, we confirmed the taxonomic status of non-T. foetus organisms isolated from preputial samples (Tetratrichomonas, Pentatrichomonas, and Pseudotrichomonas) and suggested the existence of two Tetratrichomonas species, despite their morphological similarity. The route of transmission of the non-T. foetus organisms identified in the bovine preputial cavity is discussed and we confirm that the PCR assay using the previously described T. foetus-specific primers TFR3 and TFR4 could be a useful alternative method for the diagnosis of bovine trichomonosis.

Scanning electron microscopy study of Trichomonas gallinae

A scanning electron microscopy (SEM) study of Trichomonas gallinae (Rivolta, 1878), provided more information about the morphology of this flagellated protozoan. SEM showed the morphological features of the trophozoites; the emergence of the anterior flagella, the structure of the undulating membrane, the position and shape of the pelta, axostyle and posterior flagellum. Of special interest were the pseudocyst forms.

Two-step (culture and PCR) diagnostic approach for differentiation of non-T. foetus trichomonads from genitalia of virgin beef bulls in Argentina

Preputial fluids from 567 virgin Angus and Hereford bulls, 1-2 years old, were inoculated into Sutherland medium, and approximately 8.4% produced cultures with a protozoan suggestive of Tritrichomonas foetus. Under brightfield microscopy, large numbers of single-celled motile organisms with multiple anterior flagellae, a posterior flagellum, axostyle, and a visible undulating membrane were detectable. Motility was jerky and rolling, as described for T. foetus. Air-dried smears of cultures stained with Giemsa or Diff-Quick + iodine revealed an organism similar to T. foetus, although somewhat more rounded. Several organisms appeared to have four anterior flagellae. Scanning electron microscopy (5000x) of representative samples revealed four anterior flagellae on most organisms, and an axostyle that was consistently longer than that seen in T. foetus. Using pan-trichomonal primers and T. foetus-specific primers in a polymerase chain reaction (PCR) assay, amplification products of 372bp were detected in all virgin bull isolates, but only with the pan-trichomonal primers. Positive control isolates of T. foetus yielded amplification products of the expected size (372 and 347bp) with the two sets of primers, respectively. We conclude that these protozoa are not T. foetus, and note the similarity of these findings with those reported earlier in North American beef cattle. Because in several countries there is no legal treatment for bovine trichomonosis, veterinarians recommend slaughter of bulls with positive preputial cultures. The existence of easily mis-identified non-T. foetus trichomonads in the bovine prepuce suggests that the current "gold standard" diagnostic test (culture of preputial scrapings or washings) should be augmented with a more specific confirming test, such as the PCR employed in this study.

Cell fractionation of parasitic protozoa: a review

Cell fractionation, a methodological strategy for obtaining purified organelle preparations, has been applied successfully to parasitic protozoa by a number of investigators. Here we present and discuss the work of several groups that have obtained highly purified subcellular fractions from trypanosomatids, Apicomplexa and trichomonads, and whose work have added substantially to our knowledge of the cell biology of these parasites.

Comparison of the 5.8S rRNA gene and internal transcribed spacer regions of trichomonadid protozoa recovered from the bovine preputial cavity

Sequence analysis of the 5.8S rRNA gene and the internal transcribed spacer regions (ITSRs) was used to compare trichomonadid protozoa (n = 39) of varying morphologies isolated from the bovine preputial cavity. A multiple sequence alignment was performed with bovine isolate sequences and other trichomonadid protozoa sequences available in GenBank. As a group, Tritrichomonasfoetus isolates (n = 7) had nearly complete homology. A similarity matrix showed low homology between the T. foetus isolates and other trichomonads recovered from cattle (<70%). Two clusters of trichomonads other than T. foetus were identified. Eighteen isolates comprised 1 group. These isolates shared >99% homology among themselves and with Pentatrichomonas hominis. The other non-T. foetus cluster (n = 14) did not exhibit a high degree of homology (<87%) with other bovine isolates or any of the trichomonad sequences available in GenBank. The sequence homology among isolates in that cluster was >99%, except for 1 isolate that varied from the others in both ITSRs (approximately 2% dissimilarity). Sequence analysis of the 5.8S rRNA gene and ITSRs was useful for comparing trichomonadid protozoa isolated from the bovine preputial cavity and demonstrated that 2 distinct types of trichomonads constituted the non-T. foetus isolates recovered from the bovine preputial cavity.

Special organelles of some pathogenic protozoa

Parasitic protozoa comprise a large number of species, some of which are agents of important diseases. They are also of interest from the point of view of cell biology since they contain special organelles and structures. This review analyses our present knowledge of (1). the glycosomes, found in members of the Kinetoplastida order, (2). the hydrogenosomes found in some anaerobic protozoa, especially in trichomonads, (3). the acidocalcisomes, recently described in several protozoa, and (4). structures and organelles participating in the endocytic pathway in trypanosomatids.

Trichomonas gallinae: a possible contact-dependent mechanism in the hemolytic activity

The in vitro hemolytic activity of Trichomonas gallinae was investigated. The parasite was tested against human erythrocytes of groups A, B, AB, and O, and against erythrocytes of six adult animals of different species (rabbit, rat, chicken, horse, bovine, and sheep). Results showed that T. gallinae lysed all human erythrocytes groups, as well as rabbit, rat, chicken, horse, bovine and sheep erythrocytes. No hemolysin released by the parasites could be identified. Hemolysis did not occur with trichomonad culture supernatants, with sonicated extracts of T. gallinae, or with killed organisms. The scanning electron microscopy (SEM) showed that the erythrocytes adhered to the parasite surface and were phagocytosed. These observations suggest that the contact between T. gallinae and erythrocytes may be an important mechanism in the injury caused to the erythrocytes. The hemolytic activity of T. gallinae may be an efficient means of obtaining nutrients for the parasite and allow the investigation of the mechanism used by T. gallinae to damage cellular membranes.

Tritrichomonas foetus: induced division synchrony by hydroxyurea

Treatment of cultures of Tritrichomonas foetus with 4 mM hydroxyurea (HU), a known DNA synthesis inhibitor, induced pseudocyst formation and caused a mitotic burst. An hour after drug release there was a characteristic, synchronous burst of cell division. T. foetus culture was arrested in the G2/M phase. The synchrony index varied from 66% to 69%. The synchrony was maintained for several cell cycles, even in thawed cultures which had been frozen for storage in liquid nitrogen. The synchronized cells were analyzed by light and scanning electron microscopy, as well by flow cytometry.

Morphologic aspects of Tetratrichomonas didelphidis isolated from opossums Didelphis marsupialis and Lutreolina crassicaudata

Tetratrichomonas didelphidis (Hegner & Ratcliffe, 1927) Andersen & Reilly, 1965 is a flagellate protozoan found in the intestine, cecum, and colon of Didelphis marsupialis. The parasitic protozoa used in this study was found and isolated in the intestine of opossums in Pavlova starch-containing medium in Florianópolis, State of Santa Catarina, Brazil, from D. marsupialis and Lutreolina crassicaudata. The strains were cultivated in Diamond medium without maltose and with starch solution, pH 7.5 at 28 degrees C. The specimens were stained by the Giemsa method and Heidenhain's iron hematoxylin. The light microscopy study of the trophozoites revealed the same morphologic characteristics as specimens previously described.

Contributions of the axostyle and flagella to closed mitosis in the protists Tritrichomonas foetus and Trichomonas vaginalis

Tritrichomonas foetus and Trichomonas vaginalis are protists that undergo closed mitosis: the nuclear envelope remains intact and the spindle remains extranuclear. Here we show, in disagreement with previous studies, that the axostyle does not disappear during mitosis but rather actively participates in it. We document the main structural modifications of the cell during its cell cycle using video enhanced microscopy and computer animation, bright field light microscopy, confocal laser scanning microscopy, and scanning and transmission electron microscopy. We propose six phases in the trichomonad's cell cycle: an orthodox interphase, a pre-mitotic phase, and four stages during the cell division process. We report that in T. foetus and T. vaginalis: a) all skeletal structures such as the costa, pelta-axostyle system, basal bodies, flagella, and associated filaments of the mastigont system are duplicated in a pre-mitotic phase; b) the axostyle does not disappear during mitosis, otherwise playing a fundamental role in this process; c) axostyles participate in the changes in the cell shape, contortion of the anterior region of the cell, and karyokinesis; d) flagella are not under assembly during mitosis, as previously stated by others, but completely formed before it; and e) cytokinesis is powered in part by cell locomotion.

Transient invagination of flagella by Tritrichomonas foetus

We describe an experimental system for the study of rapid and reversible formation of pseudocysts, which are spherical forms that lack a true cyst wall, by Tritrichomonas foetus, a trichomonad parasite of the bovine genitourinary tract. It highlights the dynamics of the plasma membrane and cytoskeleton of this parasite, which is perpetually devoid of any sort of protective cell wall, and can reflect a responsive survival mechanism. We have found that cooling of axenic cultures of T. foetus from their normal 37 degrees C to below about 16 degrees C can trigger pseudocyst formation. The three anterior flagella and the single recurrent flagellum can be fully internalized within 1 3 min at 37 degrees C, with the axonemes and flagellar membranes remaining intact within the cell body. Electron microscopy confirms that the internalized flagella are surrounded by a separate membrane. At 37 degrees C the internalized flagella can resume beating movements and become externalized as quickly as within 10 min. We have begun to elucidate the mechanisms of this unusual phenomenon, characterizing its temperature dependence and exploring the effects of agents that interfere with various aspects of the cytoskeleton, phagocytosis, endocytosis, and exocytosis.

Centrin protein and genes in Trichomonas vaginalis and close relatives

Anti-centrin monoclonal antibodies 20H5 and 11B2 produced against Clamydomononas centrin decorated the group of basal bodies as well as very closely attached structures in all trichomonads studied and in the devescovinids Foaina and Devescovina. Moreover, these antibodies decorated the undulating membrane in Trichomonas vaginalis, Trichomitus batrachorum, and Tritrichomonas foetus, and the cresta in Foaina. Centrin was not demonstrated in the dividing spindle and paradesmosis. Immunogold labeling, both in pre- and post-embedding, confirmed that centrin is associated with the basal body cylinder and is a component of the nine anchoring arms between the terminal plate of flagellar bases and the plasma-membrane. Centrin is also associated with the hook-shaped fibers attached to basal bodies (F1, F3), the X-fiber, and along sigmoid fibers (F2) at the pelta-axostyle junction, which is the microtubule organizing center for pelta-axostyle microtubules. There was no labeling on the striated costa and parabasal fibers nor on microtubular pelta-axostyle, but the fibrous structure inside the undulating membrane was labeled in T. vaginalis. Two proteins of 22-20 kDa corresponding to the centrin molecular mass were recognized by immunoblotting using these antibodies in the three trichomonad species examined. By screening a T. vaginalis cDNA library with 20H5 antibody, two genes encoding identical protein sequences were found. The sequence comprises the 4 typical EF-hand Ca++-binding domains present in every known centrin. Trichomonad centrin is closer to the green algal cluster (70% identity) than to the yeast Cdc31 cluster (55% identity) or the Alveolata cluster (46% identity).

Clinical and pathological observations on natural infections of cryptosporidiosis and flagellate protozoa in leopard geckos (Eublepharis macularius)

A group of adult leopard geckos (Eublepharis macularius) which had been losing weight for several months were found to be infected with Cryptosporidium species. Histological and electron microscopical investigations on the intestines of five of the lizards revealed the presence of large numbers of the developmental stages of Cryptosporidium species attached to the mucosal surface of the lower intestine, and large numbers of flagellate protozoa, suspected to be predominantly Trichomonas species, in the gut lumen. The clinical signs were attributed to the presence of one or both types of parasites.

Hydrogenosome autophagy: an ultrastructural and cytochemical study

The process of autophagy was studied in Tritrichomonas foetus under serum deprivation, drug treatment (hydroxyurea, zinc sulfate), and also in normal conditions using routine electron microscopy, freeze-fracture, freeze-substitution, and enzyme cytochemistry. We also used gold particles conjugated with bovine albumin to better characterize the participation of lysosomes in the process of hydrogenosome degradation. Apparently normal hydrogenosomes and also giant, abnormal hydrogenosomes presenting internal membranes were seen in the autophagic process. The first event observed was the rough endoplasmic reticulum surrounding and enclosing the hydrogenosome, forming an isolation membrane. The hydrogenosomes were first sequestered from the remaining cytoplasm and then degraded within lysosomes. The autophagic vacuoles were limited by double or multiple concentric membranes and many contained recognizable hydrogenosomes, probably in the preliminary steps of degradation. Lysosomes seemed to fuse with autophagic vacuoles forming a degradative structure bound by a single membrane and containing hydrogenosomes in various stages of degeneration. Hydrogenosomes appeared partially degraded, forming hydrogenosomal remnants. It was observed that there is a removal of hydrogenosomes in normal cells and in cases of cell toxicity.

Actin cytoskeleton demonstration in Trichomonas vaginalis and in other trichomonads

The flagellate form of Trichomonas vaginalis (T v) transforms to amoeboid cells upon adherence to converslips. They grow and their nuclei divide without undergoing cytokinesis, yielding giant cells and a monolayer of T v F-actin was demonstrated in Trichomonas vaginalis by fluorescence microscopy using phalloidin and an anti-actin mAb which labelled the cytoplasm of both the flagellate and amoeboid forms. Comparative electrophoresis and immunoblotting established that the actin band has the same 42 kDa as muscle actin, but 2-D electrophoresis resolved the actin band into four spots; the two major spots observed were superimposable with major muscle actin isoforms. Electron microscopy demonstrated an ectoplasmic microfibrillar layer along the adhesion zone of amoeboid T v adhering to coverslips. Immunogold staining, using anti-actin monoclonal antibodies demonstrated that this layer was mainly composed of actin microfilaments. A comparative immunoblotting study comprising seven trichomonad species showed that all trichomonads studied expressed actin. The mAb Sigma A-4700 specific for an epitope on the actin C-terminal sequence labelled only actin of Trichomonas vaginalis, Tetratrichomonas gallinarum. Trichomitus batrachorum and Hypotrichomonas acosta, but not the actin of Tritrichomonas foetus, Tritrichomonas augusta and Monocercomonas sp. This discrimination between a 'trichomonas branch' and a 'tritrichomonas branch' is congruent with inferred sequence phylogeny from SSu rRNA and with classical phylogeny of trichomonads.

Relationships of Trichomonas gallinae to the palatal-esophageal junction of ring doves (Streptopelia risoria) as revealed by scanning electron microscopy

Ring doves (Streptopelia risoria) were experimentally infected with pathogenic (virulent) Trichomonas gallinae so that trichomonad activities in the upper alimentary tract, prior to canker formation, could be examined with scanning electron microscopy. Between 6 and 15 hr postinoculation low numbers of ameboid T. gallinae were attached to apical microfolds and cell borders of the palatal-esophageal junction squamous epithelium. Initial parasite activities at tightly attached cell borders and apical microfolds suggest that some parasite-secreted factor or factors initiated squamous cell damage, separation, and removal. As squamous cell borders separated, trichomonads invaded areas beneath them and ultimately aided in their complete removal. Accelerated parasite-mediated desquamation, the invasion of increased mucosal surface area by trichomonads, and the eruption and expansion of cankers were the primary changes to the palatal-esophageal junction and other upper alimentary tract tissues that occurred between 19 and 240 hr postinoculation.

The structural organization of the pathogenic protozoan Tritrichomonas foetus as seen in replicas of quick frozen, freeze-fractured and deep etched cells

The quick-freezing and freeze-etching technique was used to analyse the cytoskeleton of Tritrichomonas foetus, a pathogenic protozoan of the urogenital tract of cattle. The cytoplasm presented a network of filamentous structures interacting with each other, with the surface of the hydrogenosomes and the nuclear membrane. Two nm wide filamentous structures were found in the luminal space of the Golgi complex, connecting the two faces of each cisterna. The microtubules of the pelta-axostyle system were connected by bridges 30-40 nm long and 10 nm wide, regularly spaced with an interval of 25 nm. The costa is a structure formed by a complex array of filaments and globous structures. It seems to be connected to the recurrent flagellum through a complex network formed by 15 and 10 nm wide filaments which emerge from the peripheral region of the costa and penetrate into the surface projections of the protozoan body to which the recurrent flagellum is attached. Other filaments were seen connecting the surface of these projections with the surface of the flagellum.

Ultracytochemical studies on Trichomonas hominis

The results of ultracytochemical studies on Trichomonas hominis showed that ACPase and CMPase were mainly located in the mature face sacs of the primary lysosomes, digestive vacuoles, as well as in the parabasal body. TPPase and NADPase were found in the saccules at the mature face and the intermediate saccules of parabasal body respectively. This study revealed that T. hominis had well-developed parabasal bodies. Negative COase and catalase reactions indicated that T. hominis lacked both mitochondria and microbody. Hydrogenosome was stained well with the Ur-Pb-Cu impregnation technique.

[Trichomonad infections of the oral cavity in horses in southern Germany]

Trichomonads of the oral cavity were found in 9 of 60 investigated horses. Apart from dental tartar, the oral cavity showed no clinical signs in all positive horses. The clinical investigation of these horses additionally revealed colic in 4 and coughing in 4 horses as well as lumbago in 1 animal. By means of scanning electron microscopy the trichomonads were shown to be round or piriform with an average length of 7.6 microns and greatest width of 6.3 microns. They had 4 anterior flagella with an average length of 8.3 microns, an undulating membrane measuring 8.7 microns with no trailing flagellum as well as an axostyle extending on average 7.8 microns beyond the body, and therefore have to be placed into the genus Trichomonas.

Ribosomes from trichomonad protozoa have prokaryotic characteristics

1. Ribosomes from cells of the genera Trichomonas and Tritrichomonas have been isolated and characterized. The ribosomes from each organism had a sedimentation coefficient of 70S in calibrated sucrose gradients and the subunits sedimented as 50S and 30S particles under the same conditions. 2. The major ribosomal RNAs from each species were identical in size to prokaryotic ribosomal RNAs when examined by denaturing gel electrophoresis. The ribosomes contained both 5.8S and 5S RNAs. 3. The ribosomal proteins were compared by the methods of two-dimensional gel electrophoresis and reversed phase HPLC. Electrophoresis of the ribosomal proteins in two different gel systems indicated the presence of 56 proteins in T. gallinae, 40 in T. bactrachorum and 45 in the Tritrichomonas sp. The protein molecular mass range was 8.5-40 kDa. 4. The HPLC analysis confirmed the protein number established by the gel methods. 5. Both methods of analysis revealed greater similarities between the ribosomal proteins of the 2 Tritrichomonas sp. than between those of the more distantly related T. gallinae and T. bactrachorum.

[Trichomonad infections of the oral cavity in cats in south Germany]

In this investigation trichomonads were isolated from the oral cavity in 21 of 110 examined cats, and only from those which were simultaneously FeLV, FIV or FIP positive. By means of scanning electron microscopy the trichomonads were shown to be round or piriform parasites which were on average 7.9 microns long and 6.2 microns wide at maximum width. They had 4 anterior flagella, which were on average 9.4 microns long, an undulating membrane measuring 6.7 microns with no trailing flagellum as well as an axostyle extending on average 5.0 microns beyond the body, and therefore should be attributed to the genus Trichomonas.

[Importance of Trichomonas tenax and Entamoeba gingivalis protozoa in the human oral cavity]

Trichomonas tenax and Entamoeba gingivalis are protozoa found in the human oral cavity. Morphological and ultrastructural characteristics of those parasites were reviewed and then studied with the scanning electron microscope in this paper. Based on previous epidemiological studies, the relationship between periodontal disease and those protozoa was analysed. Evaluation of the pathogenicity of Trichomonas tenax and Entamoeba gingivalis was also part of the discussion of this study.

The interaction of Trichomonas vaginalis and Tritrichomonas foetus with epithelial cells in vitro

The Madin-Darby canine kidney epithelial cell line (MDCK) was used as a model for trichomonad-host cell interaction. Two laboratory strains of the human parasite Trichomonas vaginalis and the cattle's parasite Tritrichomonas foetus or their supernatants from axenic cultures were allowed to interact with confluent epithelial cultures. The interaction process studied by transmission and scanning electron microscopy revealed that both parasites adhere to monolayers through flagella, cell body and particularly for T. foetus, through the posterior projection of the axostyle. A close contact region between the trichomonad's surface and MDCK cells was observed. A study of the involvement of trichomonad surface component in the interaction process indicated that cytochalasin B treated-parasites adhere much less to epithelial monolayers than untreated parasites. Colchicine treatment did not affect such adhesion. Treatment of the parasites with trypsin reduced the adhesion of trichomonads to monolayers but did not interfere with the cytopathic effect. In contrast, treatment of the parasites with neuraminidase did not interfere with their adhesion to epithelial cells and the monolayer destruction was further increased.

Trichomonas tenax: ultrastructure of giant forms

Trichomonas tenax is a parasitic flagellate of the human mouth. The morphology and the ultrastructure of the protozoan are identical to those of other trichomonads. Giant forms suddenly appeared in a strain maintained in culture for two years. The structure and the ultrastructure of these abnormal forms were studied at the light and electron microscope level. Several nuclei, groups of flagella, undulating membranes and Golgi complexes were observed. The significance of these forms is still unknown.

Tritrichomonas foetus: fine structure of freeze-fractured membranes

Freeze-fracture techniques reveal differences in fine structure between the anterior three flagella of Tritrichomonas foetus and its recurrent flagellum. The anterior flagella have rosettes of 9-12 intramembranous particles on both the P and E faces. The recurrent flagellum lacks rosettes but has ribbon-like arrays of particles along the length of the flagellum, which may be involved in the flagellum's attachment to the cell body. This flagellum is attached to the membrane of the cell body along a distinct groove that contains few discernible particles. Some large intramembranous particles are visible on the P face of the cell body membrane at the point where the flagellum emerges from the cell body. The randomly distributed particles on the P and E faces of the plasma membrane have a particle density of 919/micron2 and 468/micron2 respectively, and there are areas on both faces that are devoid of particles. Freeze-fracture techniques also reveal numerous fenestrations in the membrane of the Golgi complex and about 24 pores per micron2 in the nuclear membrane.

Cell surface carbohydrates in Tritrichomonas foetus

The cell surface of Tritrichomonas foetus was characterized by using 18 highly purified lectins with specificities for N-acetyl glucosamine, N-acetyl galactosamine, galactose, mannose, and sialic acid. The specificity of the lectin-induced cell agglutination was verified by inhibition of the agglutination with the specific sugars. By using cytochemical techniques associated with electron microscopy, carbohydrates were detected on the cell surface of T. foetus. The following techniques were used: periodic acid--thiosemicarbazide--silver proteinate, concanavalin A--horseradish peroxidase, and ruthenium red. Anionic sites were detected on the cell surface of the protozoan at pH's 1.8 and 7.2 with the use of colloidal iron hydroxide and cationized ferritin particles, respectively. The binding of colloidal iron particles, as well as the agglutination induced by the lectin from Limulus polyphemus, indicated the presence of sialic acid on the cell surface of T. foetus.

Specializations in the flagellar membrane to Tritrichomonas foetus

Tritrichomonas foetus has three anterior flagella and one recurrent flagellum. The latter originate at the anterior portion of the protozoa and extends towards the posterior region of the cell adhering to the cell body. Freeze-fracturing studies showed in the flagellar membranes of the three anterior flagella, groups of nine to 12 intramembrane particles forming rosettes which could be observed on both the P- and the E-faces of the flagellar membrane. The rosettes are numerous and found along the length of the flagella. No such structure was seen in the membrane of the recurrent flagellum. The rosettes coexist with other particles in apparently random distribution.

[Supplemental data to the ultrastructural study of Trichomonas tenax. Intra-cellular distribution of acid phosphatase]

In scanning electron microscopy, the flagella come out from the cellular body following different configurations: either separately or in groups. The undulating membrane lasted up to 2/3 of the cell body: at its end the recurrent flagella seems to penetrate again into the cell. The costa starts from the cinetosome of the recurrent flagella: the two parabasal filaments start from two different cinetosomes and follow the costa for a small distance. The nucleus is surrounded by a membrane which is not always visible. The axostyle has a cylindrical shape in the posterior two thirds of the cell. Bacteria at different stages of phagocytosis have been observed. The acid phosphatase is localized in the saccules and vesicles of the Golgi apparatus, in the lysosomes and phagolysosomes and in the terminal lamina of the undulating membrane.

Structure, protein composition and birefringence of the costa: a motile flagellar root fibre in the flagellate Trichomonas

The costa is a rod-shaped intracellular organelle lying in the cytoplasm immediately below the undulating membrane. In certain large species of Trichomonas (T. gigantea, T. termopsidis and an undescribed species from the termite Porotermes adamsoni) this organelle is motile. Bending waves are transmitted along the length of the costa, in either direction. It is shown that the bending is actively produced by the costa itself. The form of the movements is described in detail. The costa is birefringent. At the point at which bending occurs there is a sharply localized reduction in birefringence. Electron microscopy shows that the costa is composed of longitudinally running lamellae, 2–3 nm thick and spaced 12 nm apart. These are connected to transversely running elements spaced at intervals of about 37 nm. The lamellae occur in two alternative configurations: straight and zig-zag. Bending probably results from a local, transient change from the straight to the zig-zag configuration. This would account for the local change in birefringence which accompanies bending. Polyacrylamide gel electrophoresis of isolated costas shows them to contain a number of protein components, of which the principal one has a molecular weight of about 90,000. Preliminary cytochemical evidence is presented for ATPase activity in the costa. The costa is a type of motile system distinct from any hitherto described.