It has been suggested that encystment of Colpoda cucullus is mediated by intracellular Ca2+-activated signaling pathways involving an increase in the cAMP concentration. In the present study, cAMP enzyme immunoassay (EIA) and chemiluminescence detection for phosphorylated proteins using anti-phosphoserine antibody, anti-phosphothreonine antibody and biotinylated phosphate-binding tag molecules (Phos-tag) showed that the intracellular cAMP concentration in Colpoda cells was raised and the phosphorylation level of serine/threonine residues was elevated in many proteins prior to the cyst formation. Such encystment induction and protein phosphorylation were suppressed by the addition of an intracellular Ca2+ chelating reagent (BAPTA-AM) or the encystment inhibitor, chlorophyllin in all or most of these proteins, respectively. The phosphorylation level of some proteins was slightly elevated by the addition of IBMX, which tended to promote encystment induction, and tended to be slightly suppressed by the addition of H-89 (PKA inhibitor), which also suppressed encystment induction. These results suggest that Ca2+-activated signaling pathway involving cAMP/PKA-dependent protein phosphorylation may be responsible for the encystment induction of C. cucullus.

Morphological differences in cap formation were found when trophozoites of different free-living amoebae were treated with the lectin Concanavalin A, which resulted in a rapid redistribution of certain surface components to form small clusters and membrane-folded structures of diverse sizes. Acanthamoeba castellanii, Acanthamoba polyphaga and Naegleria lovaniensis exhibited characteristic caps, however, in A. castellanii this structure was larger and included several folds of the plasma membrane; furthermore, some of these caps had vacuoles containing a fi bro granular content. In contrast, the caps formed by A. polyphaga and N. lovaniensis lacked vacuoles. Regarding Naegleria fowleri, the trophozoites did not produce a defi ned cap, and only small patches of lectin-bound surface receptor complexes were observed at one pole of the cell body. In the free-living amoebae studied, it was not possible to correlate the shape and size of cap with pathogenicity.

Using standard morphological methods, we describe two new Leptopharynx species, each discovered in a specific biogeographic region and habitat. Leptopharynx bromeliophilus nov. spec., a minute species (25 × 20 μm) discovered in tanks of bromeliads from Jamaica, is small-mouthed and has a slightly concave preoral region, an average of 27 basal bodies in kinety 4, and a total of 142 basal bodies on average. Leptopharynx australiensis nov. spec., a comparatively large species (40 × 25 μm) discovered in jungle soil of Australia, is large-mouthed and has a distinctly oblique preoral region, widely spaced kinetids in kinety 1, a total of 184 basal bodies on average, and the oral primordium is inside of a cortical fold thus appearing right of the posterior end of kinety 1. Four new features are recognized for distinguishing Leptopharynx species: (1) to have a monomorphic (producing either small- or large-mouthed cells) or polymorphic (producing microstomes and macrostomes) life cycle; (2) the spacing of the kinetids in kinety 1 as either ordinary or wide; (3) the shape (flat or concave) and angle (≤ 15° slightly oblique, ≥ 40° distinctly oblique) of the preoral region; and (4) the total number of basal bodies, which has proven statistically.

The morphology and infraciliature of three marine cyrtophorid ciliates, Dysteria lanceolata Claparède and Lachmann, 1859, Lynchella nordica Jankowski, 1968 and Chlamydonyx paucidentatus Deroux, 1976, collected from the coastal waters of Qingdao, China, were investigated using live observations and the protargol impregnation method. D. lanceolata was oval in body outline, about 65 × 45 μm in vivo, with a subcaudally positioned podite, six to seven right kineties, two or three frontoventral kineties, and two ventral contractile vacuoles. The improved diagnosis for L. nordica and a key to all known Lynchella species are supplied. The rediscovery of C. paucidentatus enables us to accept its taxonomic identification (e.g., separation from a morphologically similar species Trochilioides recta). The genus Trochilioides Deroux, nov. gen., which was a nomen nudum according to ICZN (1999), is re-established.

Plasmodiophorid sporosori (aggregations of resting spores) reach their most complex form in Spongospora subterranea f. sp. subterranea, the biotrophic plant pathogen which causes the economically important disease powdery scab of potato (Solanum tuberosum). Resting spores are the perennation life cycle stage of plasmodiophorids, allowing them to survive for long periods and infect subsequent host generations. Light microscopy was used to measure resting spores and sporosori of Sp. subterranea, and enumerate resting spores in individual sporosori. Mean resting spore diameters differed for two sporosorus collections, being 4.0 μm (from New Zealand) and 4.3 μm (from Switzerland). Counts of resting spores in 4 μm thick serial sections of sporosori from one collection gave a mean of 667 (range 155 to 1,526) resting spores per sporosorus. Number of resting spores per sporosorus was closely related to sporosorus volume, and could be accurately estimated using the formula; number of resting spores = 0.0081 × sporosorus volume (assuming sporosori to be spheroids). Using this formula, mean numbers of resting spores in sporosori from 37 Sp. subterranea collections from field-grown potato tubers from 13 countries were determined to range from 199 to 713. Differences in numbers of resting spores between the collections were statistically significant (P < 0.05), and independent of country or host cultivar of origin, indicating that enumeration should be carried out for individual sporosorus collections to accurately quantify inoculum. Morphology, using scanning electron microscopy, also showed that between 2 and 51% (average 20%) of resting spores released zoospores after exposure to roots of host plants. The formula for resting spore enumeration validated in this study can be used to standardise Sp. subterranea resting spore inoculum for plant pathology studies, and possibly to assist determination of soil inoculum potential for disease risk evaluations.

Trypanosoma evansi is a blood parasite principally transmitted by mechanical vectors (tabanids and stable flies) in large animals such as livestock. However, in other types of hosts, such as carnivores and rodents, oral transmission may be more important. In this experiment, attempts were made to infect rats and mice by the peroral route using infected blood, and ticks engorged on infected rats, in order to evaluate the potential role of ticks as passive vectors of trypanosomes. A strain of Trypanosoma evansi isolated from a cow in Thailand was grown in a rat and blood was collected at the peak of parasitaemia. In the first experiment, 5 rats and 5 mice were fed respectively with 1 ml and 0.5 ml of blood containing 107 Trypanosoma evansi/ml. In the second experiment, adult ticks belonging to the species Rhipicephalus sanguineus, which had fed on parasitaemic rats, were given as food to 3 healthy rats. For both experiments, the presence of parasites in the blood of the rats and mice was checked daily for 10 days, then every 2 days for the following 20 days. Within an average of 4.5 days post blood ingestion (from 4 to 5), 80% (CI95% 29–99) of the rats exhibited parasites by direct microscopic examination of the blood. Similarly, with an average of 4.7 days post ingestion (from 4 to 6), 60% (CI95% 15–95) of the mice exhibited blood parasites. After tick ingestion, no parasites were found in the blood of the rats fed with infected engorged ticks. Consequently, in this experiment, as in others, rats and mice appeared to be receptive by the oral route, but the possible role of ticks as a passive vector could not be demonstrated. Other models could be explored, involving the cattle tick (Rhipicephalus (Boophilus) microplus), to investigate the link from large to small animals.

This current study reports a new isosporoid (Apicomplexa: Eimeriidae) species parasitizing tropical mockingbirds Mimus gilvus recovered from illegal trade in Brazil. Isospora mimusi n. sp. oocysts are spherical to sub-spherical, 20.6 × 19.6 μm, with smooth, bilayered wall, ~1.2 μm. Micropyle, oocyst residuum and polar granule are absent. Sporocysts are ovoidal, 13.4 × 9.8 μm. Stieda and substieda bodies are present. Sporocyst residuum composed of diffuse granules of various sizes, sporozoites have one refractile body.

Two new species of Phleobum (Apicomplexa: Eugregarinida: Hirmocystidae) are described from adult grasshoppers in Kalyani, India. Phleobum globuloepimeritum n. sp. is described from Oxya hyla hyla (Insecta: Orthoptera: Acrididae) and Phleobum elliptica n. sp. from Atractomorpha crenulata (Insecta: Orthoptera: Pyrgomorphidae). In P. globuloepimeritum, the trophozoites are solitary, orangecoloured, have a maximum length of 352 μm with a hyaline globular epimerite and the protomerite in satellite is characteristically flanged. The gametocyst is orange, orbicular, averaging 300 × 250 μm in size, dehiscing through a pore after 50 h. The oocysts are uniformly smooth, ellipsoidal, measuring 9 × 5 μm. In P. elliptica trophozoites are also solitary, orange-coloured, having a maximum length of 157 μm with triangular epimerites. The protomerite flange is typically a bowel-shaped collar. The gametocyst is yellow-orange, ellipsoidal, averaging 240 × 165 μm and dehisces through a pore after 72 h, releasing smooth-walled, ellipsoidal, uniformly shaped oocysts measuring 5 × 3 μm. The two new species share traits, which define the genus such as: gamonts in association, satellites with characteristic flange and gametocysts dehiscence through a single pore. The epimerite of P. globuloepimeritum is hyaline and globular, which is unique among members of the genus. The gametocyst of P. elliptica is notably ellipsoidal. Basing on observation on all the described and present two species, generic characters of the genus Phleobum have been redefined. The genus is also transferred from the family Didymophyidae to the family Hirmocystidae as the gametocysts in all the species of Phleobum dehisce through a pore.