Search Results (213)

Parasitoid venom significantly influences host physiology and development. Our previous research identified high levels of insulin-binding protein IMP-L2 in the venom of Scleroderma guani. IMP-L2 may inhibit the insulin/insulin-like growth factor signaling (IIS) cascade by competitively binding insulin-like peptides (ILPs) with insulin receptor (InR). However, how to regulate IIS transduction is unclear. We speculate that venom-derived IMP-L2 may bind ILPs to inhibit IIS transduction. Consequently, we investigated the regulation of the IIS/TOR pathway by venom-derived IMP-L2. An expression analysis of IIS/TOR pathway genes across various developmental stages of Tenebrio molitor demonstrated that this pathway governs the entire developmental process. By examining gene expression before and after parasitism, we determined that S. guani predominantly inhibits TOR pathway signaling in T. molitor post-parasitism. Bioinformatics and expression analyses revealed that IMP-L2 is critically involved in Hymenoptera insects, exhibiting high expression in the venom apparatus, and is upregulated in response to S. guani parasitism factors. Additionally, recombinant IMP-L2 was produced via eukaryotic expression. Finally, the recombinant IMP-L2 was found to inhibit the TOR and IIS/TOR signaling pathways at early (6 h) and late (24 h) stages post-injection. Knockdown of IMP-L2 in S. guani parasitized T. molitor pupae, resulting in accelerated death of T. molitor. During parasitism, S. guani may suppress host growth and development by modulating the IIS/TOR signaling pathway through venom-derived IMP-L2, potentially affecting host lifespan. Full article

Toxoplasma gondii, a parasitic protozoan, causes zoonotic infections with severe health impacts in humans and warm-blooded animals, underscoring the urgent need for effective vaccines to control these infections. In this study, a DNA vaccine encoding TgROP5, TgROP18, TgGRA7, TgGRA15, and TgMIC6 was formulated using the eukaryotic expression vector pVAX I. IL-24 was delivered as a molecular adjuvant using plasmid pVAX-IL-24. BALB/c, C57BL/6, and Kunming mouse strains received the DNA immunization, after which antibody levels, cytokine production, and lymphocyte surface markers were analyzed to assess immune responses. Additionally, survival rates and brain cyst counts were measured 1 to 2 months post-vaccination in experimental models of toxoplasmosis. As a result, compared to controls, the DNA vaccine cocktail significantly increased serum IgG levels, Th1 cytokine production, and proportions of CD4+/CD8+ T cells, leading to extended survival and reduced brain cyst counts post-challenge with T. gondii ME49. Furthermore, the five-gene DNA vaccine cocktail conferred greater protection compared to single-gene immunizations. Co-administration of IL-24 significantly enhanced the immune efficacy of the multi-gene DNA vaccination. Our findings suggest that IL-24 is an effective molecular adjuvant, enhancing the protective immunity of DNA vaccines against T. gondii, supporting its potential role in vaccine strategies targeting other apicomplexan parasites. Full article

Horizontal gene transfer (HGT), the non-Mendelian transfer of genetic material between organisms, is relatively frequent in prokaryotes, whereas its extent among eukaryotes remains unclear. Here, we raise the hypothesis of a possible cross-phylum HGT event involving 5S ribosomal DNA (rDNA). A specific type of 5S rDNA sequence from the anuran Xenopus laevis was highly similar to a 5S rDNA sequence of the genome of its flatworm parasite Protopolystoma xenopodis. A maximum likelihood analysis revealed phylogenetic incongruence between the gene tree and the species trees, as the 5S rDNA sequence from Pr. xenopodis was grouped along with the sequences from the anurans. Sequence divergence analyses of the gene region and non-transcribed spacer also agree with an HGT event from Xenopus to Pr. xenopodis. Additionally, we examined whether contamination of the Pr. xenopodis genome assembly with frog DNA could explain our findings but found no evidence to support this hypothesis. These findings highlight the possible contribution of HGT to the high diversity observed in the 5S rDNA family. Full article

Intestinal microbial eukaryotic parasites represent a significant public and veterinary health burden, especially in low- and middle-income countries, yet their transmission dynamics at the human–animal–environment interface remain poorly characterized in certain countries. This study investigated the prevalence and genetic diversity of key microbial eukaryotes, including Cryptosporidium spp., Giardia duodenalis, Blastocystis spp., Entamoeba histolytica, and Enterocytozoon bieneusi, in a rural village in Iraq. Samples collected from humans (n = 50), livestock (sheep and goats, n = 50), water (n = 20), and soil (n = 20) were analysed using microscopy and molecular methods (qPCR and nested PCR). Blastocystis spp. (78% animals, 16% humans, 45% soil, 5% water) and Cryptosporidium spp. (26% animals, 12% humans, 5% soil, 15% water) were the most frequently found microeukaryotes using either microscopy and/or molecular detection. Molecular methods identified Cryptosporidium parvum in humans and sheep, hinting at zoonotic transmission potential. Enterocytozoon bieneusi and Giardia were also found. Cryptosporidium ubiquitum and E. bieneusi genotypes BEB6 and COS-I, respectively, were detected exclusively in sheep, suggesting roles as potential reservoirs. Blastocystis ST1 was detected in humans, while ST4 and ST10 occurred in sheep. Notably, molecular detection rates of Blastocystis were much lower than those of microscopy. Entamoeba histolytica was not detected. The detection of the same organisms in humans, animals and the environment suggest zoonotic and environmental transmission pathways, which warrant further investigation using the One Health approach. Full article

The intestinal microbiota of fish is predominantly composed of prokaryotic microorganisms, with research historically focused on bacteria. In contrast, the role of microeukaryotic organisms in the fish gut remains largely unexplored. This review synthesizes current knowledge on the diversity, ecology, and potential functions of intestinal microeukaryotes, particularly fungi and protozoans, in teleost fish. Fungi, especially Ascomycota and Basidiomycota phyla members, are consistently identified across species and may contribute to digestion, immune modulation, and microbial homeostasis. Protists, though often viewed as pathogens, also exhibit potential commensal or immunoregulatory roles, including the modulation of bacterial communities through grazing. Other eukaryotic taxa, including metazoan parasites, microalgae, and zooplankton, are commonly found as transient or diet-derived members of the gut ecosystem. While many of these organisms remain poorly characterized, emerging evidence suggests they may play essential roles in host physiology and microbial balance. The review highlights the need for improved detection methodologies, functional studies using gnotobiotic and in vitro models, and multi-kingdom approaches to uncover fish gut microeukaryotes’ ecological and biotechnological potential. Full article

This review explores the interaction of annexins with membranes across a variety of eukaryotic domains of life, highlighting this protein family’s role in cellular processes due to its lipid and calcium-binding properties. By comparing annexins’ functions in diverse organisms, we aim to uncover novel insights into their mechanisms of action, particularly in membrane repair, protein trafficking, and potential channel formation. Despite extensive research on mammalian and plant annexins, there is limited information on annexins in invertebrates, fungi, and protists. This review seeks to bridge this knowledge gap, providing a comprehensive understanding of annexin–membrane interactions and their potential implications for cellular function and disease mechanisms across eukaryotic lineages. Full article

Waterborne gastrointestinal infections remain a global health concern, with approximately 1.7 billion diarrhea-related illnesses annually attributable to protozoan parasites. These pathogens are transmitted through contaminated water and exhibit high resistance to chlorination, posing substantial challenges to effective water treatment. This study focused on the most prevalent intestinal parasites in the Los Ríos Region of Chile: Blastocystis sp., Giardia duodenalis, and Entamoeba coli. The objectives were to assess the prevalence of eukaryotic parasites in water samples—covering both drinking and recreational sources—to describe the circulating subtypes of Blastocystis sp. and to identify ecological factors associated with parasite presence. Water samples were analyzed using conventional PCR, next-generation sequencing (NGS) was employed for Blastocystis sp. subtype identification, and the environmental predictors were evaluated using a multivariable logistic regression model. A total of 132 water samples were analyzed, of which 15.2% were positive for Blastocystis sp. and 1.5% for E. coli, while no samples tested positive for G. duodenalis. We identified subtypes ST1–ST4 of Blastocystis sp., along with ST7, ST10, ST14, ST21, and ST23–ST26, the latter being reported for the first time in Chile. Ecological factors significantly associated with Blastocystis sp. presence included higher water temperature and greater rainfall at positive sites. Potable water was associated with significantly lower odds of Blastocystis sp. infection (aOR = 0.04, 95% CI: 0.00–0.87; p = 0.041), while precipitation increased infection odds by 3% per additional millimeter (aOR = 1.03, 95% CI: 1.00–1.06; p = 0.036). Greater distance to the nearest farmhouse was also significantly associated with reduced infection risk, suggesting that proximity to livestock environments may influence Blastocystis sp. transmission. These findings help explain the high prevalence of Blastocystis sp. observed in humans in the Los Ríos Region and highlight the pivotal role of ecological conditions in driving waterborne transmission. To our knowledge, this is the first environmental study in Chile to clearly demonstrate the association between human infection, environmental factors, and the transmission dynamics of Blastocystis sp. Full article

Kuibyshev Reservoir, the largest in the Volga basin, is poorly covered by modern molecular studies. The results of a metabarcoding study of pro- and eukaryotic microbial plankton in its lower section during the summer period are presented. Bacterioplankton composition was typical for most temperate freshwater bodies and characterized by the dominance of cyanobacteria, Pseudomonadota, Bacteroidota, Actinomycetota, and PVC superphylum (Verrucomicrobiota and Planctomycetota), with a somewhat increased proportion of the latter. The protist community was dominated by Cryptista, principally phototrophic, and various ciliates. Several picoeukaryotic groups were newly detected in the reservoir. A relationship between the composition of both bacterioplankton and protist communities and the stage of phytoplankton succession, including the cyanobacterial bloom, was observed. Some inconsistency between the cyanobacterial bloom phase and the structure of other parts of the microbial plankton is obviously due to some temporal delay, spatial station position, and inflow from tributaries. Heterotrophic bacterioplankton indicator species of the main bloom stage include OTUs representing both the phycosphere of colonial cyanobacteria and free-living species. Among the protists, sessile ciliates benefit most from plenty of substrates for colonization, while cyanobacterial grazers and parasites were minor. Overall, the cyanobacterial bloom creates new niches for the plankton community and significantly modifies its structure. Full article

Trypanosomatids constitute a family of parasitic protozoa that cause significant human and veterinary diseases that are classified as neglected zoonotic diseases (NZDs). In a rapidly evolving world, these diseases have the potential to become a world health problem no longer solely associated with low-income countries. Therefore, the development of new strategies to control and restrain the dissemination of trypanosomatids is imperative. Extracellular vesicles (EVs) are a heterogeneous group of membrane-enclosed vesicles released by prokaryotic and eukaryotic cells. They can be found in diverse body fluids that carry biologically active molecules, including proteins, nucleic acids, lipids, and carbohydrates. EVs participate in cell-to-cell communication by delivering their cargo content to recipient cells. Thus, EVs play a role in regulating normal physiological processes, including immune surveillance and tissue repair, as well as being involved in pathological conditions, like cancer. In recent years, EVs have attracted significant attention from the scientific community, mainly due to their immune regulatory properties. Therefore, this review examines the role played by trypanosomatid-derived EVs in leishmaniases and trypanosomiasis, highlighting their biological role in host–parasite communication and exploring their potential future applications in controlling NZDs, especially those caused by trypanosomatids. Full article

Background/Objectives: Taxonomic profiling of soil microbial communities is useful for assessing and monitoring the biological status of agricultural land. In this study, we aimed to investigate changes in the taxonomic structure of soil organisms in minimally managed agricultural fields. Methods: We used DNA metabarcoding to investigate both terrestrial prokaryotes and eukaryotes in cabbage-cultivated and uncultivated sites in a minimally managed agricultural field in central Japan from February to August 2021. Analyses of the relative abundances of prokaryotic and eukaryotic sequence variants (SVs) and their β-diversities, and the subsequent redundancy analysis (RDA) clarified the dynamic changes in eukaryotic communities during cultivation. We further investigated taxonomic changes in fungi-, protist-, and animal-derived SVs, abundant SVs in each eukaryotic phylum, as well as the co-occurrence networks of the top 150 SVs. Results: The results revealed that the fractions of predatory or parasitic protists and animals increased, whereas those of fungi and earthworm Enchytraeus spp. decreased. The fractions of abundant SVs derived from diatoms, Ciliophora, the class Vampyrellidae (Cercozoa), and mites increased and subsequently decreased during this period. These findings suggest that predatory protists and animals fed on bacteria and autotrophic eukaryotes (such as diatoms) propagated in spring, followed by their propagation and parasitism to host eukaryotes. The networks also changed, especially prokaryotic networks that markedly changed from April to May, and those of eukaryotes from May to June–August, supporting the observations mentioned above. Conclusions: These findings indicate the dynamic and sequential changes in soil communities in fields with minimal agricultural practices and could be useful for sustainable natural farming. Full article

The 20S proteasome, a critical component of the ubiquitin–proteasome system, plays a central role in regulating protein degradation in eukaryotic cells. Marizomib (MZB), also known as salinosporamide A, is a natural γ-lactam-β-lactone compound derived from Salinispora tropica and is a potent 20S proteasome covalent inhibitor with demonstrated anticancer properties. Its broad-spectrum inhibition of all three proteasome subunits and its ability to cross the blood–brain barrier has made it a promising therapeutic candidate for glioblastoma. In addition to this, MZB also demonstrates significant inhibition against the 20S proteasome of Trichomonas vaginalis (Tv20S), a protozoan parasite, suggesting its potential for parasitic treatments. Here, we present the cryo-EM structure of the human 20S proteasome in complex with MZB at 2.55 Å resolution. This structure reveals the binding mode of MZB to all six catalytic subunits within the two β-rings of the 20S proteasome, providing a detailed molecular understanding of its irreversible inhibitory mechanism. These findings enhance the therapeutic potential of MZB for both cancer and parasitic diseases at the molecular level and highlight marine-derived natural products in targeting the proteasome for therapeutic applications. Full article

NGS sequencing data are expanding exponentially, accompanied by a concomitant growth in non-target species contamination. Meanwhile, these seemingly undesirable sequences can actually provide valuable insights into the broad-scale diversity and distribution of their parasites or symbionts. In this study, we developed a pipeline called DBCscreen (DNA Barcode Contamination screen) to explore biodiversity and distribution across a broad range of living organisms, based on a DNA barcode contamination survey. We used DBCscreen to screen 39,302 eukaryotic assemblies in the NCBI TSA/WGS database, and after stringent filtering, we ultimately identified 110,880 contaminated contigs related to DNA barcodes in 10,717 assemblies. Subsequently, the taxonomic information of these contaminants was determined, and their heterogeneous distribution patterns revealed complex relationships between the hosts (assembly source) and their associated parasites or symbionts (contaminants). Finally, several application examples demonstrating the use of DBCscreen were described, such as identification of the most easily contaminated organisms associated with a specific host (ex. ticks), as well as the specification of which hosts are particularly prone to certain types of contamination (ex. Wolbachia and nematodes). Full article

Signal-dependent transport into and out of the nucleus mediated by members of the importin (IMP) superfamily is crucial for eukaryotic function, with inhibitors targeting IMPα being of key interest as anti-infectious agents, including against the apicomplexan Plasmodium species and Toxoplasma gondii, causative agents of malaria and toxoplasmosis, respectively. We recently showed that the FDA-approved macrocyclic lactone ivermectin, as well as several other different small molecule inhibitors, can specifically bind to and inhibit P. falciparum and T. gondii IMPα functions, as well as limit parasite growth. Here we focus on the FDA-approved antiparasitic moxidectin, a structural analogue of ivermectin, for its IMPα-targeting and anti-apicomplexan properties for the first time. We use circular dichroism and intrinsic tryptophan fluorescence measurements to show that moxidectin can bind directly to apicomplexan IMPαs, thereby inhibiting their key binding functions at low μM concentrations, as well as possessing anti-parasitic activity against P. falciparum in culture. The results imply a class effect in terms of IMPα’s ability to be targeted by macrocyclic lactone compounds. Importantly, in the face of rising global emergence of resistance to approved anti-parasitic agents, the findings highlight the potential of moxidectin and possibly other macrocyclic lactone compounds as antimalarial agents. Full article

During the trophic period of myxomycetes, the plasmodia of myxomycetes can perform crawling feeding and phagocytosis of bacteria, fungi, and organic matter. Culture-based studies have suggested that plasmodia are associated with one or several species of bacteria; however, by amplicon sequencing, it was shown that up to 31–52 bacteria species could be detected in one myxomycete, suggesting that the bacterial diversity associated with myxomycetes was likely to be underestimated. To fill this gap and characterize myxomycetes’ microbiota and functional traits, the diversity and functional characteristics of microbiota associated with the plasmodia of six myxomycetes species were investigated by metagenomic sequencing. The results indicate that the plasmodia harbored diverse microbial communities, including eukaryotes, viruses, archaea, and the dominant bacteria. The associated microbiomes represented more than 22.27% of the plasmodia genome, suggesting that these microbes may not merely be parasitic or present as food but rather may play functional roles within the plasmodium. The six myxomycetes contained similar bacteria, but the bacteria community compositions in each myxomycete were species-specific. Functional analysis revealed a highly conserved microbial functional profile across the six plasmodia, suggesting they may serve a specific function for the myxomycetes. While the host-specific selection may shape the microbial community compositions within plasmodia, functional redundancy ensures functional stability across different myxomycetes. Full article

The eukaryotic ribosome is a large ribonucleoprotein complex consisting of four types of ribosomal RNA (rRNA) and approximately 80 ribosomal proteins (RPs), forming the 40S and 60S subunits. In all living cells, its primary function is to produce proteins by converting messenger RNA (mRNA) into polypeptides. In addition to their canonical role in protein synthesis, RPs are crucial in controlling vital cellular processes such as cell cycle progression, cellular proliferation, differentiation, DNA damage repair, genome structure maintenance, and the cellular stress response. Viruses, as obligate intracellular parasites, depend completely on the machinery of the host cell for their replication and survival. During viral infection, RPs have been demonstrated to perform a variety of extra-ribosomal activities, which are especially important in viral disease processes. These functions cover a wide range of activities, ranging from controlling inflammatory responses and antiviral immunity to promoting viral replication and increasing viral pathogenicity. Deciphering the regulatory mechanisms used by RPs in response to viral infections has greatly expanded our understanding of their functions outside of the ribosome. Furthermore, these findings highlight the promising role of RPs as targets for the advancement of antiviral therapies and the development of novel antiviral approaches. This review comprehensively examines the many functions of RPs outside of the ribosome during viral infections and provides a foundation for future research on the host–virus interaction. Full article