Three new species of Eimeria Schneider 1875 in the montane grass mouse, Akodon montensis (Rodentia: Cricetidae: Sigmodontinae), and redescription of Eimeria zygodontomyis Lainson and Shaw 1990 from southeastern Brazil.

We describe three new coccidian species of the genus Eimeria Schneider 1875 (Apicomplexa: Eimeriidae) and redescribe and report Eimeria zygodontomyis Lainson and Shaw, 1990 in the montane grass mouse, Akodon montensis Thomas, 1913 from the Serra dos Órgãos National Park in southeastern Brazil. Sporulated oocysts of Eimeria zygodontomyis are ellipsoidal to cylindrical with a 0.6 (0.5-0.8) µm thick very delicate bi-layered wall; length × width (n = 49) 18.3 × 12.5 (16-20 × 11-13) µm; length/width ratio of 1.4 (1.2-1.6); 1 polar granule occasionally present; micropyle, residuum both absent. Sporocysts are ellipsoidal; length × width 8.5 × 5.2 (8-11 × 5-6) µm; length/width ratio of 1.5 (1.3-1.7) µm; Stieda body is prominent; sub-Stieda body is absent; sporocyst residuum is compact. Sporulated oocysts of Eimeria montensis n. sp. are spheroidal to subspheroidal with a 1.2 (1.0-1.4) µm thick bi-layered wall; outer layer lightly pitted; length × width (n = 30) 16.3 × 12.5 (15-17 × 13-15) µm; length/width ratio of 1.3 (1.0-1.4); 1 polar granule present; micropyle, residuum both absent. Sporocysts are ellipsoidal; length × width 7.2 × 5.1 (6-8 × 4-6) µm; length/width ratio of 1.4 (1.2-1.6); Stieda body is present, sub-Stieda body is absent; sporocyst residuum consists of small, scattered granules. Sporulated oocysts of Eimeria uricanensis n. sp. are ovoidal to pyriform with a 1.4 ( 1.3-1.6) µm thick bi-layered wall; outer layer lightly pitted; length × width (n = 40) 26.6 × 18.6 (23-30 × 17-20) µm; length/width ratio of 1.4 (1.3-1.6); 1 polar granule present; micropyle, residuum both absent. Sporocysts are ellipsoidal, length × width 13.3 × 8.0 (10-16 × 7-9) µm; length/width ratio of 1.7 (1.5-1.9); Stieda body, sub-Stieda body both absent; sporocyst residuum consists of a cluster of granules, forming a spheroid mass. Sporulated oocysts of Eimeria parnasiensis n. sp. are subspheroidal to ellipsoidal with a 1.8 ( 1.3-2.4) µm thick bi-layered wall; outer layer lightly pitted; length × width (n = 54) 28.2 × 21.9 (26-32 × 19-28) µm; length/width ratio of 1.3 (1.2-1.4); 1 polar granule present; micropyle is absent; oocyst residuum is present and consists of a cluster of granules of varying thickness. Sporocysts are ovoidal, tapering towards the Stieda body; length × width 12.2 × 7.6 (10-13 × 6-9) µm; length/width ratio of 1.6 (1.4-1.9); Stieda body is present; sub-Stieda body is absent; sporocyst residuum is present and consists of an aggregate of thin granules.

CXCL10 treatment promotes reduction of IL-10+ regulatory T (Foxp3+ and Tr1) cells in the spleen of BALB/c mice infected by Leishmania infantum.

American visceral leishmaniasis is caused by the protozoan Leishmania infantum. The control of the disease depends on the magnitude of the Th1 cell response and IL-10 producing regulatory T cells. Administration of chemokine, such as CXCL10, has shown promising results in the leishmaniasis treatment. Previous studies from our group have shown that CXCL10 induces a reduction in parasite burden in the spleen and a decrease in IL-10 and TGF-ß production in L. infantum-infected BALB/c mice. This work investigated whether CXCL10-treatment reduces IL-10 + Treg cell populations (CD4+CD25+Foxp3+ and Tr1) and induces morphological changes in the spleen. BALB/c mice were infected and treated or not with CXCL10 on the 1st, 3rd and 7th days of infection. CXCL10-treatment was able to reduce the parasite load in the spleen in L. infantum-infected BALB/c mice and this decrease in the number of parasites correlated with the decrease in size of this organ in treated animals compared to untreated animals. 7, 23, and 45 days post-treatment (p.t.), the phenotype and frequency of IL-10 + Treg cells were evaluated by flow cytometry, and the morphological changes of the spleen were analyzed by optical microscopy. After 7 and 23 days p.t., CXCL10-treated animals showed a significant reduction of CD25-Foxp3-IL-10+ (Tr1) cells in the spleen when compared to untreated animals, whereas CD4+CD25+Foxp3+IL-10+ Treg cells reduced later at 23rd and 45th days p.t. Furthermore, while untreated animals showed a significant positive correlation between IL-10 production and Tr1 cells, in CXCL10-treated group this correlation was negative. Thus, these findings show that treatment with CXCL10 chemokine in L. infantum-infected BALB/c mice results in suppression of IL10+ Treg (Foxp3+ and Tr1) cells in the spleen, associated with a reduction in parasite load and splenomegaly.

A new species of Eimeria Schneider, 1875 from the Serra dos Órgãos National Park, Rio de Janeiro, Brazil, with notes on its endogenous development in the montane grass mouse, Akodon montensis Thomas, 1913 (Rodentia: Sigmodontinae).

A total of 53 specimens of the montane grass mouse, Akodon montensis Thomas, 1913 were collected in the Serra dos Órgãos National Park (SONP) in November 2014 and July 2015. The fecal material was analyzed, and a prevalence of 7.5% was recorded for a new coccidian species of the genus Eimeria Schneider, 1875, with part of its endogenous development recorded in the small intestine. The oocysts of a new coccidian species of genus Eimeria are ellipsoidal to subspherical. The wall is bi-layered, c. 1.5 µm (1.3-1.6 µm) thick, outer layer rough. Oocyst (n = 126) mean length is 25.3 µm (21.0-28.0 µm), with a width of 20.2 µm (17.0-22.0 µm) and mean length/width (L:W) ratio of 1.3 (1.2-1.4). Polar granule is present, with the oocyst residuum as a large spherical to subspherical globule. Sporocyst shape (n = 126) is ellipsoidal, with a mean length of 11.8 µm (9.3-14.4 µm), width of 7.9 µm (6.7-9.3 µm), and mean L:W ratio of 1.5 (1.4-1.7). Sporocysts with nipple-like Stieda body and sub-Stieda body are absent. A sporocyst residuum formed by several globules, usually along the sporocyst wall. This is the first record of Eimeria in the montane grass mouse from Brazil.

Protection mediated by chemokine CXCL10 in BALB/c mice infected by Leishmania infantum.

BACKGROUND: Visceral leishmaniasis (VL) caused by Leishmania infantum is characterised by the loss of the ability of the host to generate an effective immune response. Chemokines have a direct involvement in the pathogenesis of leishmaniasis, causing a rapid change in the expression of these molecules during infection by Leishmania. OBJECTIVES: Herein, it was investigated the role of CXCL10 in controlling infection by L. infantum. METHODS: RAW 264.7 macrophages were infected with L. infantum in vitro and treated or not with CXCL10 (25, 50 and 100 ng/mL). Parasite load, as well as nitric oxide (NO), IL-4 and IL-10 production were assessed at 24 and 48 h after infection. In vivo, BALB/c mice were infected and treated or not with CXCL10 (5 µg/kg) at one, three and seven days of infection. Parasite load, IFN-g, IL-4, TGF-ß and IL-10 were evaluated one, seven and 23 days post treatment. FINDINGS: In vitro, CXCL10 reduced parasitic load, not dependent on NO, and inhibited IL-10 and IL-4 secretion. In vivo, CXCL10 was able to reduce the parasite load in both liver and spleen, four weeks after infection, representing a higher decrease in the number of parasites in these organs, also induced IFN-γ at day 23 after treatment, correlating with the decrease in parasite load, and reduced IL-10 and TGF-ß. MAIN CONCLUSIONS: This study suggests a partial protective role of CXCL10 against L. infantum, mediated by IFN-g, not dependent on NO, and with suppression of IL-10 and TGF-ß. These data may provide information for the development of new approaches for future therapeutic interventions for VL.

The cannabinoid 2 receptor agonist ß-caryophyllene modulates the inflammatory reaction induced by Mycobacterium bovis BCG by inhibiting neutrophil migration.

OBJECTIVE AND DESIGN: ß-Caryophyllene (BCP) is a sesquiterpene that binds to the cannabinoid 2 (CB2) receptor and exerts anti-inflammatory effects. In this study, we investigated the anti-inflammatory effect of BCP and another CB2 agonist, GP1a in inflammatory experimental model induced by Mycobacterium bovis (BCG). METHODS: C57Bl/6 mice were pretreated orally with BCP (0.5-50 mg/kg) or intraperitonealy with GP1a (10 mg/kg) 1 h before the induction of pleurisy or pulmonary inflammation by BCG. The direct action of CB2 agonists on neutrophils function was evaluated in vitro. RESULTS: ß-Caryophyllene (50 mg/kg) impaired BCG-induced neutrophil accumulation in pleurisy without affecting mononuclear cells or the production of TNF-α and CCL2/MCP-1. However, BCP inhibited CXCL1/KC, leukotriene B4 (LTB4), IL-12, and nitric oxide production. GP1a had a similar effect to BCP. Preincubation of neutrophils with BCP (10 µM) impaired chemotaxis toward LTB4 and adhesion to endothelial cells stimulated with TNF-α, and both, BCP and GP1a, impaired LTB4-induced actin polymerization. CONCLUSION: These results suggest that the CB2 receptor may represent a new target for modulating the inflammatory reaction induced by mycobacteria.

The morphological analysis of autophagy in primary skeletal muscle cells infected with Toxoplasma gondii.

Toxoplasma gondii is an obligate intracellular protozoan parasite, the causative agent of toxoplasmosis, one of the most widespread zoonoses in the world. During the host immune response, tissue cysts are formed, allowing the maintenance of the parasite within the host cell. Autophagy, a degradation process of cellular components, is critical for cellular homeostasis. Recently, it has been proposed that autophagy participates in host-pathogen interactions. Autophagic inducers (rapamycin or glucose plus serum deprivation) inhibited infection and parasite proliferation in a clinically relevant model of primary skeletal muscle cells (SkMC). The ultrastructural analysis showed in SkMC submitted to autophagic stimuli the presence of structures suggestive of autophagosomes close to the parasitophorous vacuole containing degraded parasites. Fluorescence microscopy results pointed out the increase in LC3 puncta in these cells after incubation with autophagic inducers. In the present study, SkMC autophagy controlled the proliferation of tachyzoites inside the cell, data reinforced by ultrastructural evidences and increased LC3 expression.

Microglial NLRP3 Inflammasome Induces Excitatory Synaptic Loss Through IL-1ß-Enriched Microvesicle Release: Implications for Sepsis-Associated Encephalopathy.

Acute cerebral dysfunction is a pathological state common in severe infections and a pivotal determinant of long-term cognitive outcomes. Current evidence indicates that a loss of synaptic contacts orchestrated by microglial activation is central in sepsis-associated encephalopathy. However, the upstream signals that lead to microglial activation and the mechanism involved in microglial-mediated synapse dysfunction in sepsis are poorly understood. This study investigated the involvement of the NLRP3 inflammasome in microglial activation and synaptic loss related to sepsis. We demonstrated that septic insult using the cecal ligation and puncture (CLP) model induced the expression of NLRP3 inflammasome components in the brain, such as NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3), apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC), caspase-1, and IL-1ß. Immunostaining techniques revealed increased expression of the NLRP3 inflammasome in microglial cells in the hippocampus of septic mice. Meanwhile, an in vitro model of primary microglia stimulated with LPS exhibited an increase in mitochondrial reactive oxygen species (ROS) production, NLRP3 complex recruitment, and IL-1ß release. Pharmacological inhibition of NLRP3, caspase-1, and mitochondrial ROS all decreased IL-1ß secretion by microglial cells. Furthermore, we found that microglial NLRP3 activation is the main pathway for IL-1ß-enriched microvesicle (MV) release, which is caspase-1-dependent. MV released from LPS-activated microglia induced neurite suppression and excitatory synaptic loss in neuronal cultures. Moreover, microglial caspase-1 inhibition prevented neurite damage and attenuated synaptic deficits induced by the activated microglial MV. These results suggest that microglial NLRP3 inflammasome activation is the mechanism of IL-1ß-enriched MV release and potentially synaptic impairment in sepsis.

Benznidazole and amiodarone combined treatment attenuates cytoskeletal damage in Trypanosoma cruzi-infected cardiac cells.

Chagas disease (CD), a neglected tropical disease caused by the protozoan parasite Trypanosoma cruzi, is an important public health problem mainly in Latin America, leading to approximately 12,000 annual deaths. Current etiological treatment for CD is limited to two nitro compounds, benznidazole (Bz) and nifurtimox (Nif), both presenting relevant limitations. Different approaches have been employed to establish more effective and safer schemes to treat T. cruzi infection, mostly based on drug repurposing and combination therapies. Amiodarone (AMD), an antiarrhythmic medicament of choice for patients with the chronic cardiac form of CD, is also recognized as a trypanocidal agent. Therefore, our aim is to investigate the combined treatment Bz + AMD on trypomastigote viability, control of T. cruzi intracellular form proliferation, and recovery of the infection-induced cytoskeleton alterations in cardiac cells. The combination of Bz + AMD did not improve the direct trypanocidal effect of AMD on the infective blood trypomastigote and replicative intracellular forms of the parasite. Otherwise, the treatment of T. cruzi-infected cardiac cells with Bz plus AMD attenuated the infection-triggered cytoskeleton damage of host cells and the cytotoxic effects of AMD. Thus, the combined treatment Bz + AMD may favor parasite control and hamper tissue damage.

Social preference is maintained in mice with impaired startle reflex and glutamate/D-serine imbalance induced by chronic cerebral toxoplasmosis.

Toxoplasma gondii is an opportunistic protozoan pathogen with a wide geographic distribution. The chronic phase of toxoplasmosis is often asymptomatic in humans and is characterized by tissue cysts throughout the central nervous system and muscle cells. T. gondii and other pathogens with tropism for the central nervous system are considered risk factors in the etiology of several neuropsychiatric disorders, such as schizophrenia and bipolar disorder, besides neurological diseases. Currently, it is known that cerebral toxoplasmosis increases dopamine levels in the brain and it is related to behavioral changes in animals and humans. Here we evaluate whether chronic T. gondii infection, using the cystogenic ME-49 strain, could induce behavioral alterations associated with neuropsychiatric disorders and glutamatergic neurotransmission dysfunction. We observed that the startle amplitude is reduced in the infected animals as well as glutamate and D-serine levels in prefrontal cortical and hippocampal tissue homogenates. Moreover, we did not detect alterations in social preference and spontaneous alternation despite severe motor impairment. Thus, we conclude that behavioral and cognitive aspects are maintained even though severe neural damage is observed by chronic infection of C57Bl/6 mice with the ME-49 strain.

Interaction and cystogenesis of Toxoplasma gondii within skeletal muscle cells in vitro.

Infection by the protozoan parasite Toxoplasma gondii is widely prevalent in humans and animals. To prevent human infection, all meat should be well cooked before consumption, since the parasite is present in skeletal muscle. In this context, the use of skeletal muscle cells (SkMCs) as a cellular model opens up new approaches to investigate T. gondii-host cell interactions. Immunofluorescent detection of proteins that are stage-specific for bradyzoites indicated that complete cystogenesis of T. gondii in in vitro cultures of SkMCs occurs after 96 h of infection. Ultrastructural analysis showed that, after 48 h of interaction, there were alterations on the parasitophorous vacuole membrane, including greater thickness and increased electron density at the inner face of the membrane. The present study demonstrates the potential use of primary cultures of SkMCs to evaluate different molecular aspects of T. gondii invasion and cystogenesis and presents a promising in vitro model for the screening of drug activities toward tissue cysts and bradyzoites.

The life history of Pygidiopsis macrostomum Travassos, 1928 (Digenea: Heterophyidae).

The life history of the trematode Pygidiopsis macrostomum Travassos, 1928 is described for the first time. Rediae and cercariae were obtained from naturally infected snails Heleobia australis (d Orbigny), a new first intermediate host. Metacercariae were found encysted in the mesenteries of three naturally infected guppies, Phalloptychus januarius (Hensel), Jenynsia multidentata (Jenyns) (new host records) and Poecilia vivipara Bloch and Schneider. Experimental infections were successfully completed in the intermediate hosts H. australis and Poe. vivipara reared in the laboratory and hamsters Mesocricetus auratus Waterhouse were utilised as a definitive host.

Primary culture of intestinal epithelial cells as a potential model for Toxoplasma gondii enteric cycle studies.

The primary culture of intestinal epithelial cells from domestic cats is an efficient cellular model to study the enteric cycle of Toxoplasma gondii in a definitive host. The parasite-host cell ratio can be pointed out as a decisive factor that determines the intracellular fate of bradyzoites forms. The development of the syncytial-like forms of T. gondii was observed using the 1:20 bradyzoite-host cell ratio, resulting in similar forms described in in vivo systems. This alternative study potentially opens up the field for investigation into the molecular aspects of this interaction. This can contribute to the development of new strategies for intervention of a main route by which toxoplasmosis spreads.

Spontaneous stage differentiation of mouse-virulent Toxoplasma gondii RH parasites in skeletal muscle cells: an ultrastructural evaluation.

Although the predilection for Toxoplasma gondii to form cysts in the nervous system and skeletal and heart muscles has been described for more than fifty years, skeletal muscle cells (SkMCs) have not been explored as a host cell type to study the Toxoplasma-host cell interaction and investigate the intracellular development of the parasite. Morphological aspects of the initial events in the Toxoplasma-SkMC interaction were analysed and suggest that there are different processes of protozoan adhesion and invasion and of the subsequent fate of the parasite inside the parasitophorous vacuole (PV). Using scanning electron microscopy,Toxoplasma tachyzoites from the mouse-virulent RH strain were found to be attached to SkMCs by the anterior or posterior region of the body, with or without expansion of the SkMC membrane. This suggests that different types of parasite internalization occurred. Asynchronous multiplication and differentiation of T. gondii were observed. Importantly, intracellular parasites were seen to display high amounts of amylopectin granules in their cytoplasm, indicating that tachyzoites of the RH strain were able to differentiate spontaneously into bradyzoites in SkMCs. This stage conversion occurred in approximately 3% of the PVs. This is particularly intriguing as tachyzoites of virulent Toxoplasma strains are not thought to be prone to cyst formation. We discuss whether biological differences in host cells are crucial to Toxoplasma stage conversion and suggest that important questions concerning the host cell type and its relevance in Toxoplasma differentiation are still unanswered.

Giardia lamblia: a report of drug effects under cell differentiation.

The Giardia lamblia life cycle is characterized by two phases during which two major cell differentiation processes take place: encystation and excystation. During encystation, the trophozoites transform into cysts, the resistance form. Once ingested by a susceptible host, the cysts are stimulated to excyst in the stomach, and the excysted trophozoites adhere to the epithelium of the upper small intestine. Our work analyses the effects of four benzimidazole derivatives during Giardia differentiation into cysts and evaluates the excystation efficiency of water resistant cysts. Albendazole (AB) showed the most significant results by inhibiting encystation about 30% and a decreasing rate of excystation efficiency. The ultrastructural organization of the cyst adhesive disk was notably affected by AB treatment. Although other benzimidazoles showed some effect on encystation, they were not able to inhibit the excystation process. It is known that the benzimidazoles affect the cytoskeleton of many organisms but how it interferes in Giardia differentiation processes is our main focus. The importance of studying Giardia's differentiation under drug action is reinforced by the following arguments: (1) Cysts eliminated by hosts undergoing treatment could still be potentially infective; (2) once the host has been treated, it would be desirable that the shedding of cysts into the environment is avoided; (3) the prevention of Giardia dissemination is a question of extreme importance mainly in underdeveloped countries, where poor sanitary conditions are related to high rates of giardiasis. This report concerns the importance of keeping the environment free from infective cysts and on Giardia's drug resistance and differentiating abilities.

Toxoplasma gondii Impairs Myogenesis in vitro, With Changes in Myogenic Regulatory Factors, Altered Host Cell Proliferation and Secretory Profile.

Toxoplasma gondii is the causative agent of toxoplasmosis, a parasitic disease with a wide global prevalence. The parasite forms cysts in skeletal muscle cells and neurons, although no evident association with inflammatory infiltrates has been typically found. We studied the impact of T. gondii infection on the myogenic program of mouse skeletal muscle cells (SkMC). The C2C12 murine myoblast cell line was infected with T. gondii tachyzoites (ME49 strain) for 24 h followed by myogenic differentiation induction. T. gondii infection caused a general decrease in myotube differentiation, fusion and maturation, along with decreased expression of myosin heavy chain. The expression of Myogenic Regulatory Factors Myf5, MyoD, Mrf4 and myogenin was modulated by the infection. Infected cultures presented increased proliferation rates, as assessed by Ki67 immunostaining, whereas neither host cell lysis nor apoptosis were significantly augmented in infected dishes. Cytokine Bead Array indicated that IL-6 and MCP-1 were highly increased in the medium from infected cultures, whereas TGF-ß1 was consistently decreased. Inhibition of the IL-6 receptor or supplementation with recombinant TGF-ß failed to reverse the deleterious effects caused by the infection. However, conditioned medium from infected cultures inhibited myogenesis in C2C12 cells. Activation of the Wnt/ß-catenin pathway was impaired in T. gondii-infected cultures. Our data indicate that T. gondii leads SkMCs to a pro-inflammatory phenotype, leaving cells unresponsive to ß-catenin activation, and inhibition of the myogenic differentiation program. Such deregulation may suggest muscle atrophy and molecular mechanisms similar to those involved in myositis observed in human patients.

Primary culture of skeletal muscle cells as a model for studies of Toxoplasma gondii cystogenesis.

Toxoplasma gondii is a protozoan pathogen of birds and mammals, including humans. The infective stage, the bradyzoite, lives within cysts, which occur predominantly in cells of the central nervous system and skeletal and cardiac muscles, characterizing the chronic phase of toxoplasmosis. In the present study, we employed for the first time primary mouse culture of skeletal muscle cells (SkMC) infected with bradyzoites, as a cellular model for cystogenesis. The interconversion of bradyzoite and tachyzoite was analyzed by immunofluorescence using 2 stage-specific antibodies, i.e., anti-bradyzoite (anti-BAG1) and anti-tachyzoite (anti-SAG1). After 24 hr of interaction only bradyzoites were multiplying, as revealed by anti-BAG1 incubation; interconversion to tachyzoites was not observed. After 48 hr of infection, 2 types of vacuoles were seen, i.e., BAG1+ and SAG1+, indicating the presence of bradyzoites as well as their interconversion to tachyzoites. After 96 hr of infection, BAG1+ vacuoles presented a higher number of parasites when compared to 48 hr, indicating multiplication of bradyzoites without interconversion. Using ultrastructural analysis, bradyzoites were found to adhere to the cell membranes via both the apical and posterior regions or were associated with SkMC membrane expansions. During bradyzoite invasion of SkMC, migration of the rough endoplasmic reticulum (RER) profiles to the parasite invasion site was observed. Later, RER profiles were localized between the mitochondria and parasitophorous vacuole membrane (PVM) that contained the parasite. After 31 days of parasite-host cell infection, RER profiles and mitochondria were not observed in association with the cyst wall. Alterations of the PVM, including increased thickness and electrondensity gain on its inner membrane face, were observed 48 hr after infection. Cystogenesis was complete 96 hr after infection, resulting in the formation of the cyst wall, which displayed numerous membrane invaginations. In addition, an electron-dense granular region enriched with vesicles and tubules was present, as well as numerous intracystic bradyzoites. These results show that the in vitro T. gondii model and SkMC are potential tools for both the study of cystogenesis using molecular approaches and the drug screening action on tissue cysts and bradyzoites.

Balantioides coli: morphological and ultrastructural characteristics of pig and non-human primate isolates.

Balantioides coli is a ciliated protozoon that inhabits the intestine of pigs, non-human primates and humans. Light microscopy studies have described over 50 species of the genus Balantioides but their validity is in doubt. Due to the limited information about this genus, this study is aimed to identify morphological characteristics of Balantioides coli isolated using fluorescence microscopy and both scanning (SEM) and transmission electron microscopy (TEM). Trophozoites isolated from the feces of pig and macaque were washed and subjected to centrifugation. These cells were fixed with paraformaldehyde for immunofluorescence. Other aliquots of these trophozoites were fixed with glutaraldehyde, post fixed with osmium tetroxide and processed for SEM and TEM. Immunofluorescence studies revealed microtubules with a longitudinal distribution to the main axis of the parasite and in the constitution of cilia. SEM demonstrated a high concentration of cilia covering the oral apparatus and a poor presence of such structures in cytopyge. TEM revealed in the plasma membrane, several associated structures were observed to delineate the cellular cortex and mucocysts. The cytoskeleton of the oral region was observed in detail and had an organization pattern consisting of microtubules, which formed files and nematodesmal networks. Organelles such as hydrogenosomes like and peroxisomes were observed close to the cortex. Macronuclei were observed, but structures that were consistent with micronuclei were not identified. Ultrastructural morphological analysis of isolates confirms its similarity to Balantioides coli. In this study were identified structures that had not yet been described, such as hydrogenosomes like and cytoskeletal structures.

Morphological effects on helminth parasites caused by herbicide under experimental conditions.

Helminth parasites have been studied as potential accumulators for different pollutants. Echinostoma paraensei is a foodborne trematode whose vertebrate host, the rodent Nectomys squamipes, is naturally exposed to environmental pesticides. However, little information exists regarding the pesticide's effects on helminths. This study investigated the morphological effects on the trematode, E. paraensei, after experimental Roundup® herbicide exposure, in concentrations below those recommended for agricultural use. After two hours of exposure, scanning electron microscopy (SEM) showed changes to the tegument, such as furrowing, shrinkage, peeling, spines loss on the peristomic collar, and histopathological evidence of altered cells in the cecum and acinus vitelline glands with vacuoles and structural changes to the muscular layers. Glycidic content was decreased, primarily in the connective tissue. As E. paraensei is an intestinal parasite of the semi-aquatic wild rodent, N. squamipes, it is predisposed to pesticide exposure resulting from agricultural practices. Therefore, we emphasize the need to evaluate its impact on helminth parasites, due to their pivotal role in regulating host populations.

Anionic sites on Toxoplasma gondii tissue cyst wall: expression, uptake and characterization.

Toxoplasmosis, caused by Toxoplasma gondii, is an important parasitic disease worldwide, which causes widespread human and animal diseases. The need for new therapeutic agents along with the biology of these parasites has fueled a keen interest in the understanding of the nutrients acquisition by these parasites. Studies on the characterization of the T. gondii cyst wall as well as the contribution of the host cell to this formation have been little explored. The aim of this paper was to investigate the electric surface charge of the T. gondii tissue cysts by ultrastructural cytochemistry, through polycationic markers, employing ruthenium red (RR) and cationized ferritin (CF). Glycosaminoglycans revealed by RR were localized on the cyst wall as a homogeneous granular layer electrondense, all over its surface. The incubation of living tissue cysts with CF for 20 min at 4 degrees C followed by the increase of temperature to 37 degrees C indicated that T. gondii cyst wall is negatively charged and that occurs an incorporation of anionic sites by the cyst wall, through vesicles and tubules, and their posterior location in the cyst matrix. So, as to identify which group of molecules produces negative charge in the cyst wall, we used enzymes for cleavage on different types of molecules, demonstrating that the negative charge in the cyst wall is mainly produced by phospholipids. Our results, described in this work show, for the first time, the negativities of the cyst wall, the incorporation and the traffic of intracellular surface molecules by T. gondii cyst wall. Our model of study can give an important contribution to the knowledge of the biology and the processes involved in nutrients acquisition by bradyzoites living inside the cysts and, and also be applied as a target for the direct action of drugs against the cyst.

Redescription of Ascocotyle (Ascocotyle) felippei Travassos, 1928 (Digenea: Heterophiydae) with new synonymies.

The heterophyid trematode Ascocotyle (Ascocotyle) felippei Travassos, 1928, is redescribed and new data on its life cycle are provided, based on types and metacercariae found in the heart bulb and gills of naturally infected guppies, Poecilia vivipara (new fish intermediate host), from a coastal lagoon in Rio de Janeiro, Brazil. Examination of the type and all voucher specimens of A. (A.) felippei collected by Travassos in the type host and locality in Brazil has shown that they possess only 32 (16 + 16) circumoral spines, rather than 36 (18 + 18) spines as previously reported. Based on the identical number and arrangement of circumoral spines, shape of the body, the presence of a long preoral lobe and posterior muscular prolongation of the oral sucker, short and wide ceca, a simple gonotyl lacking refractile bodies, and the site of infection of metacercariae (predominantly heart bulb), A. (A.) puertoricensis Price, 1932 and A. (A.) tenuicollis Price, 1935, are proposed as new synonyms of A. (A.) felippei.