Search Results (7)

The objective of this study was to evaluate the diversity and prevalence of tick-borne protists in the Republic of Korea via DNA barcoding using 18S rRNA gene fragments and PCR. Between 2021 and 2022, questing ticks were collected using the flagging method, with a total of 13,375 ticks collected and pooled into 1003 samples. Of these, 50 tick pools were selected for DNA barcoding targeting the V4 and V9 regions of 18S rRNA using the MiSeq platform. A taxonomic analysis of the amplicon sequence variants identified three genera of protozoa, namely Hepatozoon canis, Theileria luwenshuni, and Gregarine sp. However, the number and abundance of protists detected were different depending on the primer sets, and T. gondii was not identified in DNA barcoding. Furthermore, conventional PCR confirmed the presence of H. canis, Toxoplasma gondii, T. luwenshuni, and Theileria sp. in the collected ticks. This study identified H. canis and T. gondii in Ixodes nipponensis for the first time. It demonstrated that the results of DNA barcoding using 18S rRNA gene fragments can vary depending on the primer sets and further optimization is required for library construction to identify tick-borne protists in ticks. Despite these limitations, the findings highlight the potential of DNA barcoding using 18S rRNA gene fragments for screening the diversity of tick-borne protists in ticks. Full article

Environmental contamination with xenobiotics affects organisms and the symbiotic relations between them. A convenient object to study relationships between parasites and their hosts is the host–parasite system “Tenebrio molitor Linnaeus, 1758 (Coleoptera, Tenebrionidae)—Gregarina polymorpha (Hammerschmidt, 1838) Stein, 1848 (Eugregarinorida, Gregarinidae)”. For this experiment, we took 390 T. molitor larvae and 24 organic compounds. Groups of mealworms, 15 in each, were subjected to those compounds for 10 days. Then, we recorded the vitality of both the larvae of T. molitor and G. polymorpha. To assess how G. polymorpha had affected the hosts’ wellbeing, we looked for changes in the larvae’s body mass and compared them to the number of gregarines in their intestines. The vitality of the larvae was inhibited by cyclopentanol and 2-naphthol. The intensity of gregarine invasion was reduced by diphenyl ether, benzyl alcohol, catechol, and 3-aminobenzoic acid. No effect on the number of gregarines was produced by 3,4,5-trihydroxybenzoic acid, cyclohexanemethanol, phenol, benzalkonium chloride, maleic anhydride, cyclohexanol, resorcin, benzoic acid, 2-methylfuran, terpinen-4-ol, 1-phenylethylamine, dibutyl phthalate, 3-furancarboxylic acid, 5-methyl furfural, 6-aminohexanoic acid, succinic anhydride, o-xylene, and benzaldehyde. In the infected T. molitor individuals, the mean number of G. polymorpha equaled 45 specimens per host. The groups of smaller mealworms had fewer gregarines. Positive correlation was seen between growth rates of T. molitor larvae and the intensity of invasion by gregarines. Full article

The order Protococcidiida is one of the most poorly studied basal groups of Sporozoa (Apicomplexa sensu stricto). To date, the phylogenetic unity of protococcidians and their relationship with other sporozoans are understudied. Only the protococcidian Eleutheroschizon duboscqi has molecular evidence of a sister position to “true” coccidians (Eimeria, Sarcocystis, Toxoplasma). E. duboscqi is characterized by epicellular development in the so-called parasitophorous sac of the host cell origin. The unusual localization of Eleutheroschizon is comparable to that of Cryptosporidium. We describe a new species of the genus, E. planoratum ex Naineris quadricuspida polychaete from the White Sea, using light and electron microscopy. The morphology of attachment apparatus, phylogenetic analyses of concatenated DNA sequences of the nuclear ribosomal operon (SSU rDNA, ITS1, 5.8S rDNA, ITS2, and LSU rDNA), and compensatory base changes in ITS2 secondary structures of both protococcidians confirm the new species. The resulting phylogenies also confirm that Eleutheroschizon is sister to eimeriid coccidians, while Cryptosporidium tends to be grouped with gregarines. We discuss a new type of endoparasitism among sporozoans—the closed epicellular parasitism that evolved convergently in Eleutheroschizon and Cryptosporidium. The diagnosis of the new species and the emended diagnoses of the species E. duboscqi and the genus Eleutheroschizon are presented. Full article

Metchnikovellids (Microsporidia: Metchnikovellida) are poorly studied hyperparasitic microsporidia that live in gregarines inhabiting the intestines of marine invertebrates, mostly polychaetes. Our recent studies showed that diversity of metchnikovellids might be significantly higher than previously thought, even within a single host. Four species of metchnikovellids were found in the gregarines inhabiting the gut of the polychaete Pygospio elegans from littoral populations of the White and Barents Seas: the eugregarine Polyrhabdina pygospionis is the host for Metchnikovella incurvata and M. spiralis, while the archigregarine Selenidium pygospionis is the host for M. dogieli and M. dobrovolskiji. The most common species in the White Sea is M. incurvata, while M. dobrovolskiji prevails in the Barents Sea. Gregarines within a single worm could be infected with different metchnikovellid species. However, co-infection of one and the same gregarine with several species of metchnikovellids has never been observed. The difference in prevalence and intensity of metchnikovellid invasion apparently depends on the features of the life cycle and on the development strategies of individual species. Full article

Transposable elements (TEs) are mobile genetic elements found in the majority of eukaryotic genomes. Genomic studies of protozoan parasites from the phylum Apicomplexa have only reported a handful of TEs in some species and a complete absence in others. Here, we studied sixty-four Apicomplexa genomes available in public databases, using a ‘de novo’ approach to build candidate TE models and multiple strategies from known TE sequence databases, pattern recognition of TEs, and protein domain databases, to identify possible TEs. We offer an insight into the distribution and the type of TEs that are present in these genomes, aiming to shed some light on the process of gains and losses of TEs in this phylum. We found that TEs comprise a very small portion in these genomes compared to other organisms, and in many cases, there are no apparent traces of TEs. We were able to build and classify 151 models from the TE consensus sequences obtained with RepeatModeler, 96 LTR TEs with LTRpred, and 44 LINE TEs with MGEScan. We found LTR Gypsy-like TEs in Eimeria, Gregarines, Haemoproteus, and Plasmodium genera. Additionally, we described LINE-like TEs in some species from the genera Babesia and Theileria. Finally, we confirmed the absence of TEs in the genus Cryptosporidium. Interestingly, Apicomplexa seem to be devoid of Class II transposons. Full article

The phylum Apicomplexa is a major group of protozoan parasites including gregarines, coccidia, haemogregarines, haemosporidia and piroplasms, with more than 6000 named species. Three of these subgroups, the coccidia, hemosporidia, and piroplasms, contain parasites that cause important diseases of humans and animals worldwide. All of them have complex life cycles involving a switch between asexual and sexual reproduction, which is key to their development. Fertilization (i.e., fusion of female and male cells) results in the formation of a zygote that undergoes meiosis, forming a new generation of asexual stages. In eukaryotes, sexual reproduction is the predominant mode of recombination and segregation of DNA. Sex is well documented in many protist groups, and together with meiosis, is frequently linked with transmission to new hosts. Apicomplexan sexual stages constitute a bottleneck in the life cycle of these parasites, as they are obligatory for the development of new transmissible stages. Consequently, the sexual stages represent attractive targets for vaccination. Detailed understanding of apicomplexan sexual biology will pave the way for the design and implementation of effective transmission-blocking strategies for parasite control. This article reviews the current knowledge on the sexual development of Apicomplexa and the progress in transmission-blocking vaccines for their control, their advantages and limitations and outstanding questions for the future. Full article

Protozoa, of the taxon Gregarinasina, are a heterogeneous group of Apicomplexa that includes ~1600 species. They are parasites of a large variety of both marine and terrestrial invertebrates, mainly annelids, arthropods and mollusks. Unlike coccidians and heamosporidians, gregarines have not proven to have a negative effect on human welfare; thus, they have been poorly investigated. This study focuses on the molecular identification and phylogeny of the gregarine species found in the midgut of two insect species that are considered as an alternative source of animal proteins for the human diet: the mealworm Tenebrio molitor, and the super-worm Zophobas atratus (Coleoptera: Tenebrionidae). Gregarine specimens were isolated from the gut of both larval and adult stages of T. molitor specimens, as well as from Z. atratus larvae. The morphological analyses were restricted to the identification of the different parasite morpho-types, likely corresponding either to different life-cycle stages or to alternative gregarine species. The samples were also used for the DNA extraction necessary for their genetic characterization. Finally, the efficiency of different molecular markers (i.e., 18S rDNA gene alone or combined with the Internal Transcribed Spacer 1) was assessed when applied either to gregarine species identification and to phylogenetic inference. Full article