Based on morphological, morphometric and infraciliature criteria, as evidenced by the ammoniacal pyridinated silver carbonate technique and 4',6-diamidino-2-phenylindole (DAPI) staining, we contribute to the knowledge of four new ciliated protozoa species from the digestive tract of earthworms (Oligochaete: Glossoscolecidae), collected on the banks of the Nkam River (Cameroon). These new species belong to the Class Armophorea, the genera Nyctotherus and Nyctotheroides. In the genus Nyctotherus, three species are described: N. nkamensis n. sp. (ovoid, 85-138 m 52-115 m), N. emini n. sp. (ovoid, 66-185 m 50-95 m), and N. renimorphus n. sp. (kidney form, 125-220 m 75-180 m). They have in common the presence of an apical secant system on their right side. In the genus Nyctotheroides, the species N. ndogbeleensis n. sp. (elongated form, 75-120 m 25-40 m) is characterized by the existence of three secant systems on both sides: an apical secant system on the right side and two secant systems (the apical and the caudal) on the left side. Contrary to known congeners, the species described in this study have a very pronounced polymorphism.

This article presents a life story of Prof. K.S. Merezhkovsky and his contribution to protistology and evolution theory. Despite the conventional point of view, he cannot be treated as a pure botanist, but rather as protistologist, zoologist, and even a successful anthropologist and science fiction writer.

The marine planktonic dinoflagellate Prorocentrum cordatum (syn. Prorocentrum minimum) is a thecate species capable of ecdysis, i.e. rearrangement of the cell covering in response to different stressors. During the process of ecdysis, P. cordatum cells shed the plasma membrane and outer amphiesmal vesicle membrane, and become immotile, covered only by thecal plates and the new plasma membrane. At this stage, the cells can be considered as thecal cysts. Then, they complete ecdysis by leaving the old thecal plates and restoring motility, i.e. excyst. To elucidate the role of vesicular transport in the cell covering rearrangement, we tested the effect of brefeldin A, the inhibitor of vesicular transport from the endoplasmic reticulum to the Golgi complex widely used in cell biology, on the cellular structure of P. cordatum and its ability to ecdyse. We found out that brefeldin A blocked vesicular trafficking from the endoplasmic reticulum to the Golgi complex, since we observed disassembly of the Golgi complex in cells treated by brefeldin A at 0.1 g/ml for 1 h. Moreover, such a treatment did not increase mortality in P. cordatum culture at the time scale of 6 h. Nevertheless, our experiments demonstrated that brefeldin A affected neither shedding of outer membranes nor discarding of thecal plates during the stressorinduced ecdysis. Based on our findings, we conclude that vesicle trafficking from the endoplasmic reticulum to the Golgi complex and further to the plasma membrane is not essential to the process of membrane and theca shedding. However, this route still can be involved in the process of new amphiesma' maturation, which is discussed in this work.

A number of methods to detect microsporidia infections are based on recovery of spores due to their thick refractive spore walls and presence of chitin that easily binds to fluorogenic and chromogenic stains. Visualization of intracellular stages in infected cells and organs has been always a challenge. In this report a new immunodetection method based on the use of -tubulin antibodies, has been developed to mark the intracellular life cycle stages of Vairimorpha (Nosema) ceranae, an emergent pathogen of Apis mellifera. For this purpose, we carried out the heterologous expression of the V. ceranae -tubulin gene in E. coli cells and obtained polyclonal antibodies to the recombinant protein. The antibodies were successfully applied for immunolabelling of microsporidian cells in insect midguts in vivo as well as in Sf9 cell culture in vitro.

Predatory protists are poorly studied, although they are often representing important deep-branching evolutionary lineages and new eukaryotic supergroups.This short review/opinion paper is inspired by the recent discoveries of various predatory flagellates, which form sister groups of the giant eukaryotic clusters on phylogenetic trees, and illustrate an ancestral state of one or another supergroup of eukaryotes.Here we discuss their evolutionary and ecological relevance and show that the study of such protists may be essential in addressing previously puzzling evolutionary problems, such as the origin of multicellular animals, the plastid spread trajectory, origins of photosynthesis and parasitism, evolution of mitochondrial genomes.

Arcellinida is an Amoebozoa lineage characterized by the presence of an external shell. A comprehensive cyto-morphological description of the shell structure and formation (thecagenesis) process has been generated due to publications in the time span of more than a century. Recently, few works have advanced our understanding of the thecagenesis process or discussed this rich literature; however, several aspects of the shell formation and structure are still puzzles, as remains the relationship between genes and shell formation morphogenesis. Here we present an overview of the literature about shell formation and structure, focusing on the genus Arcella, the best-studied lineage. We show that some aspects regarding shell formation are still open questions. Moreover, based on the current knowledge, we can establish new frameworks, to address such issues as the origin and evolution of the shell in Arcellinida.