Testate amoebae (TA) are unicellular protozoans enclosed in a test capable of indicating a wide variety of environmental conditions. Among others, characteristics such as short life cycle, great sensitivity and worldwide distribution makes them adequate bioindicators. As a complement to physical and chemical measurements, biomonitoring can be a cheaper and fastest way of environmental monitoring. This research sought to evaluate the extent of TA use in biomonitoring and the responses given by them to environmental features. The research was conducted in Scielo, Science Direct, Online Library, Google Scholar and Capes Journal Portal and yielded 211 papers. TA bioindication is able to provide information on metal, trace element and atmospheric pollution, and to point out different trophic states, pH, and evidence on characteristics of hydrology. Further, TA can be used in paleoenvironmental reconstruction as they reflect climate, volcanic and even sea level change phenomena. Sometimes, together with other organisms in environmental analysis, they have shown to be an important complement to biomonitoring. Additionally, a functional traits approach has been recently included as a promising tool. Methodological adjustments that have been conducted throughout the years are allowing TA use to be more reliable and precise. This review provides insight on the many possible functions of TA in bioindication studies, highlighting their wide use as bioindicators.

Cryptosporidium parvum, an Apicomplexan parasite, is an important cause of diarrheal disease, especially in immunodeficient hosts. Nevertheless, there is no entirely successful therapeutic agent against cryptosporidiosis to date. Hence, this study aims to test the potential prophylactic and therapeutic effect of Camellia sinensis (green tea extract) in dexamethasone immunosuppressed mice versus the nowadays used drug, Nitazoxanide (NTZ). Parasitological and molecular methods were used to characterize Cryptosporidium oocysts before infection. Fifty bred female Swiss Albino mice were divided into 5 groups; group I (GI)(GTP): immunosuppressed and prophylactically treated with green tea extract for 5 days prior to infection, group II (GII)(GTT): immunosuppressed, infected with Cryptosporidium parvum and treated with green tea extract, group III (GIII)(NT): immunosuppressed, infected and treated with NTZ, group IV (GIV)(PC): immunosuppressed and infected (Positive control), group V (GV)(NC): immunosuppressed and non-infected (Negative control). Furthermore, parasitological examination for oocysts in the stool, and histopathological examination for the small intestine and liver specimens were performed for the study groups. Cryptosporidium oocysts used for induction of infection proved to be Cryptosporidium parvum genotype 2. Moreover, a significant oocyst reduction in fecal samples correlated with an improvement of histopathological changes in the small intestinal and liver tissues in GI(GTP), GII (GTT) and GIII(NT) groups. Besides, the GII(GTT) group showed the best improvement in parasitological and histopathological parameters among the test groups. This study revealed that Camellia sinensis (green tea extract) has potential activity against cryptosporidiosis and could serve as a promising prophylactic and therapeutic anti-cryptosporidial agent.

Ciliates have a long history of being central in evolutionary and ecological studies on eukaryotic microorganisms. Although thousands of species have been discovered, their total diversity still remains unknown. Here, we will discuss two unsolved problems that hinder the further exploration of ciliate diversity at the species level, and potential solutions to these problems are proposed. First, ciliate morphospecies are difficult to identify because the different silver stains are not scalable (they do not represent high-throughput methods) and basic supplies are lacking (e.g., protargol); a solution may be the development of fluorescent staining techniques. Second, ciliate phylogenetic species are difficult to identify because of extensive paralogy in nuclear-protein-coding genes; a solution may be to concentrate on sequencing mitochondrial genomes. These two approaches could be integrated into a high-throughput fluorescent-single-cell sorting and mitochondrial genomes sequencing process that would enable the observation and better understanding of ciliate species on a massive scale.

The application of molecular phylogenetics to research on protists has substantially transformed our understanding of their evolution and systematics. More recently, advances in molecular technology, including high throughput sequencing, has opened new avenues for genomic analyses that elucidate major aspects of protistan biology across all levels of biological organization from cellular to ecosystems. This is a review of recent advances (particularly in the last two decades) of transcriptomic research on heterotrophic and autotrophic protists within three major topics: (i) Physiology and metabolism, (ii) Development and life cycles, and (iii) Environmental and ecological studies. Emphasis is placed on selection of representative research that highlights findings across diverse taxonomic groups within each of the three topics. Examples are drawn from parasitic as well as free-living taxa to provide a broad overview of some of the research strategies, and major findings, that have emerged from application of transcriptomics and related techniques in advancing our understanding of protistan biology.

Marshes bordering rivers and estuaries are productive ecosystems that interact dynamically with the adjacent water mass. This is a multi-year study (2019–2022) of seasonal changes in the density of naked amoebae in monthly samples from the surface water of the Hudson estuary near Piermont, N. Y. with relationships to key environmental variables (surface water temperature, salinity, Secchi depth representing turbidity, and enterococcus bacterial counts). During the colder months (November to March), when decayed leaves and litter from the deciduous marsh grass produced organic matter in the sediment surface, the mean abundance of active amoebae ± standard error of the mean (SEM) was higher (3.07 ± 0.99 × 10⁴/ L, N = 7). In warmer months (May to September) the abundance of amoebae was lower (1.35 ± 0.29 × 10⁴ / L, N = 10). A multivariate linear regression analysis was performed relating amoeba abundance to four major water mass variables, resulting in the following statistically significant equation (p = 0.03): A_D = 0.121 × T + 0.301 × L – 0.047 × S + 0.359 ×  C,  where: AD = active amoebae density (× 10 /L), T = temperature ( C), L = tide level (m), S = Secchi disc depth (cm) and C = bacterial enterococcus concentration (number/ml). In general, given the increasing evidence of the potential importance of amoeboid protists in aquatic ecosystems, further research is warranted on their role in food webs and the carbon biogeochemical cycle within heterotrophic estuarine and coastal waters.

This study was carried out in two hypersaline lakes (Acı and Meke Lakes) in Turkey to understand the diversity and geographic distribution of free-living heterotrophic flagellates. Heterotrophic flagellates of hypersaline environments have not previously been studied in Turkey. We found seventeen morphospecies of heterotrophic flagellates with one unidentified protist. The observed species belong to Craspedida, Heterolobosea, Apusomonadida, Neobodonida, Bicosoecida and Protista incertae sedis. Of the 17 species, ten species were new records for Turkey. All of the morphospecies described here except one unidentified protist were previously reported elsewhere and appear to be cosmopolitan.