This review summarizes the application of Tetrahymena spp. in ecotoxicology, in order to promote a more integrated, multi-level ecotoxicological assessment approach regarding the effects of chemical stressors on several biological levels (from molecule to ecosystem). Such a multi-level testing approach in one species facilitates the establishment of missing causal relationships between biochemical responses and ecological effects. The review illustrates that Tetrahymena spp. represent excellent ecotoxicological test species due to their important role in the microbial foodweb, wide distribution and abundance, sequenced genome in T. thermophila, large background knowledge and scientific publications in cellular biology, ecology and ecotoxicology. Several bioassays have already been developed on different biological organisation levels, such as enzyme assays (biochemical level), behavioral tests (individual level), population growth tests (population level) and microcosms (community level). Moreover, specific mode-of-action based assays are available (e.g. genotoxicity), or are in development (e.g. endocrine disruption and neurotoxicity). Tetrahymena spp. combine traits of (1) a single cell, thus might replace or complement specific cell-line testing approaches, with traits of (2) a whole organism and population, thus allowing to study complete metabolic pathways and its consequences on population growth and genetic adaptation. Assays involving Tetrahymena spp. might easily be adapted for a rapid multi-level in situ or ex situ toxicity biosensor test system for ecologically relevant risk assessment.

Complementary DNAs (cDNAs) of protein phosphatase 2C (PP2C) were cloned from two marine scuticociliates Uronema marinum and Miamiensis avidus. Both PP2C proteins showed structural characteristics of typical PP2C, such as highly conserved amino acid residues predicted for binding to phosphate and metal ions, 11 conserved PP2C motifs and 10 invariant residues. The phosphatase activity of recombinantly produced U. marinum PP2C (UmPP2C) was in proportion to the PP2C protein and Mg2+ concentrations, and was not sensitive to okadaic acid, but was inhibited by sodium fluoride, EDTA or Ca2+. The expression of UmPP2C was significantly up-regulated by exposure the ciliates with PMA suggesting that UmPP2C dephosphrylates proteins phosphorylated by protein kinases as in other eukaryotes and has a regulatory function against abrupt increase of protein phosphorylation triggered by strong stimulations.

Acanthamoeba polyphaga trophozoites bind yeast cells of Candida albicans isolates within a few hours, leaving few cells in suspension or still attached to trophozoite surfaces. The nature of yeast cell recognition, mediated by an acanthamoebal trophozoite mannose binding protein is confi rmed by experiments utilizing concentration dependent mannose hapten blocking. Similarly, acapsulate cells of Cryptococcus neoformans are also bound within a relatively short timescale. However, even after protracted incubation many capsulate cells of Cryptococcus remain in suspension, suggesting that the capsulate cell form of this species is not predated by acanthamoebal trophozoites.

Further aspects of the association of Acanthamoeba and fungi are apparent when studying their interaction with conidia of the biocontrol agent Coniothyrium minitans. Conidia which readily bind with increasing maturity of up to 42 days, were little endocytosed and even released. Cell and conidial surface mannose as determined by FITC-lectin binding, fl ow cytometry with associated ligand binding analysis and hapten blocking studies demonstrates the following phenomena. Candida isolates and acapsulate Cryptococcus expose most mannose, while capsulate Cryptococcus cells exhibit least exposure commensurate with yeast cellular binding or lack of trophozoites. Conidia of Coniothyrium, albeit in a localized fashion, also manifest surface mannose exposure but as shown by Bmax values, in decreasing amounts with increasing maturity. Contrastingly such conidia experience greater trophozoite binding with maturation, thereby questioning the primacy of a trophozoite mannose-binding-protein recognition model.

The genus Eimeria Schneider, 1875, comprises of > 1,000 described species, making it the most species-rich among coccidians. Within chelonian hosts, only 61 Eimeria spp. have been described to date, with the majority known from the New World. Yet, the Southeast Asia region has the highest turtle diversity in the world, from which only a few species have been discovered. Furthermore, the largest turtle family, Geoemydidae Theobald, 1868, has received little attention. In the past decade we examined samples from wild-caught geoemydid turtles from Southeast Asia and adjacent areas. Our work revealed considerable diversity of turtles’ coccidia and we describe six new species of Eimeria in this report. Eimeria surinensis sp. n. from Malayemys subtrijuga caught in Thailand possesses almost spherical oocysts (22.6 × 21.4), with spindle-shaped to ellipsoidal sporocysts pointed at both poles (13.4 × 6.9). Eimeria pangshurae sp. n. from Pangshura sylhetensis residing in India has ellipsoidal to spherical oocysts (16.5 × 13.2) and broadly-ellipsoidal to fl ask-shaped sporocysts (11.1 × 5.7), with a Stieda body frequently connected with two to four fi laments. Eimeria hynekprokopi sp. n. from Vietnamese Cuora galbinifrons has extremely thin-walled and fragile, elongated oocysts, and is a bit pointed at one pole (15.6 × 8.7), carrying ellipsoidal to broadly oval sporocysts (6.5 × 4.3). Eimeria zbatagura sp. n. from Batagur baska sampled in Singapore has tiny sub-spherical to broadly ellipsoidal oocysts (7.4 × 6.3 μm) with almost oval but relatively small sporocysts (5.5 × 3 μm). The broadly ellipsoidal, fragile oocysts of Eimeria petrasi sp. n. (22.9 × 18.6 μm) collected from Cyclemys dentata in the Philippines possess a wavy outer surface of the oocyst wall, and oval to ellipsoidal sporocysts (12.3 × 6.5 μm). Eimeria palawanensis sp. n. from Cyclemys dentata found in the Philippines has thin-walled and fragile spherical oocysts (14–17 μm wide), plus elongated, ellipsoidal sporocysts (12.6 × 5.8 μm). We also recorded Eimeria arakanensis Široky et Modry, 2006 from the new host species – Cuora fl avomarginata collected in China. Since many chelonians are critically endangered species, their parasite biodiversity will be lost following the collapse of their populations.

The composition (143 species and forms) of testate amoebae communities from 68 samples of soils and lake sediments from South Vietnam (Cat Tien National Park) was investigated. In most terrestrial habitats, hydrophilous, soil and even xerophilous testaceans were co-occurring. The likely reason for this phenomenon are sharp seasonal changes in hydrological regime including temporal overwetting or inundation. Typical members of soil communities were Plagiopyxis callida, Tracheleuglypha acolla, Euglypha cristata, E. tuberculata, Trinema complanatum. The fauna was composed mainly of eurybiont species. Less abundant but still common were moss-dwelling species from the genera Heleopera, Hyalosphenia, Nebela and Sphenoderia. Calciphilous species were also present, including Centropyxis plagiostoma, Geopyxella cf. sylvicola, Schwabia terricola, Plagiopyxis callida, P. intermedia v. cyrtostoma, Heleopera petricola v. humicola. Species from the genera Hoogenraadia, Planhoogenraadia, Apolimia were found in this region of South-East Asia for the first time. The variations in the species composition and diversity of testate amoebae in soils was likely caused by several mechanisms including local variations in hydrological regime, the differences in chemical and physical properties and decomposition rates of plant litter, and mineralogical features of soils. The fauna of lake sediments was very distinct with characteristic species Difflugia bacillariarum, Lesquereusia modesta, Arcella gibbosa, Euglypha acanthophora. In the relatively uniform lake sediments local microcommunities were rich in species but very similar in species composition (low beta-diversity). In contrast, in soil samples the micro-scale heterogeneity was usually very pronounced, though the alpha-diversity was lower than in lake sediments. The updated list of testate amoebae of Vietnam includes 237 taxa. Taxa with restricted geographical distribution form up to one tenth of the total species richness.

The largest known Aspidisca species, A. magna Kahl, 1932, was found from coastal waters near Qingdao (Tsingtao), northern China, and investigated using both the “wet” silver nitrate and protargol staining method. Based on the living observation and impregnated individuals, improved diagnosis and morphometric data are provided. As an additional contribution, the morphogenesis in Aspidisca magna during binary fission was revealed and summarized as follows: 1) the parental adoral zone of membranelles and paroral membranęare retained by the proter; 2) the oral primordium of the opisthe develops hypoapokinetally behind the posterior part of the adoral zone of membranelles; 3) five frontoventral-transverse cirral anlagen are formed de novo, initially as primary primordia, and develop into 3:3:2:2:1 cirri from left to right, respectively in both dividers; 4) the leftmost frontoventral cirrus is generated from an independently formed cirral anlage in both dividers. In the present work, Chinese and Korean populations of A. leptaspis Fresenius, 1865 were investigated respectively to support the importance of living characteristics in identification of Aspidisca species. The isolation of A. magna and A. leptaspis from other congeners are also firmly demonstrated by the SSU rRNA gene sequence alignments.

The Silent Valley National Park in the state of Kerala, India, ranks high among the biodiversity hotspots of the world with 4.8 as the alpha diversity index. The Valley is surrounded by mountain ranges and has a diverse topography with a mosaic of varied habitats that have remained isolated from extraneous influences. The present report describes urostyloid ciliates from diverse ecozones within the core zone of the National Park. Six species of the urostyloids, including Anteholosticha angida n. sp. and Bakuella nilgiri n. sp., were found in soil samples. Anteholosticha angida n. sp. differs from its cogeners in having a unique combination of characters – presence of colourless cortical granules, ~ 53 macronuclear nodules, ~ 3 micronuclei, ciliature with 3–4 buccal cirri in a row and 4 dorsal kineties. Bakuella nilgiri n. sp. is characterized by the presence of colourless cortical granules, ~ 98 macronuclear nodules, 3–4 micronuclei, ciliature with 4–8 buccal cirri in a row and a mid-ventral complex comprising of ~ 21 cirral pairs and 2–10 cirri in 2–3 rows reaching up to the level of the 6–11 transverse cirri.

The noctilucoid dinoflagellates have been investigated in the open waters of the Mediterranean Sea. Kofoidinium spp., Spatulodinium spp. and Scaphodinium mirabile were found in nearly all the stations. The genera Craspedotella, Leptodiscus, Petalodinium and Pomatodinium were recorded for the first time in the eastern Mediterranean basin. An undescribed small species of Kofoidinium (40–60 μm in diameter) with a pointed extension represented about 1/3 of the genus records. The monotypic character of the genus Spatulodinium needs to be reconsidered because numerous specimens differed from the type species. One of these undescribed species showed a distinctive hyposome and an extremely long tentacle (up to 1600 μm long). A leptodiscacean that showed an arrowhead-shaped contour is found for the first time in the Mediterranean Sea. There is a considerable diversity of noctilucaceans yet to be described.