Search Results (423)

The study investigated the diversity and ecology of Myxomycetes (Amoebozoa) along a vegetation gradient in the Cuzco department, Peru, spanning altitudes from 2500 to 4700 m. Field collections were carried out at six sites distributed across three distinct vegetation formations: non-Amazonian Forest, paramo, and high Andean zones with and without vegetation cover. The collected material was analyzed through direct observation, cultivation in moist chambers, and morphological identification, resulting in the record of 18 species, including three new records for Peru (Diderma circumdissilens, Licea tenera, and Perichaena luteola). Species richness was higher at lower altitudes and in environments with greater substrate availability, such as dead branches and mosses, but declined under extreme environmental conditions, particularly at high elevations. Principal component analysis revealed differences in community composition among the environments, associated with environmental variables and substrate types. The results highlight that the Peruvian Andes harbor a significant biodiversity of Myxomycetes, including species adapted to high-altitude conditions, reinforcing the importance of conservation and further study of these extreme ecosystems. We conclude that high mountain environments serve as biodiversity hotspots, and that future studies, including molecular techniques, are essential to understanding the distribution and adaptation of these organisms in the Andean environments. Full article

Labyrinthulomycetes protists play important roles in organic matter decomposition and nutrient cycling in marine ecosystems. To better understand their distribution and potential ecological functions in Caofeidian seagrass beds of the Bohai Sea, we conducted high-throughput sequencing of samples collected from multiple habitats, including leaves (L), rhizosphere (R), sediments (S), and seawater (W). Our results revealed distinct habitat-specific patterns of community composition. Oblongichytrium and Stellarchytrium were dominant in certain samples, exhibiting clear differences across stations. Oblongichytrium showed particularly high abundance in leaf and seawater samples, likely reflecting the availability of particulate and dissolved substrates enriched by seagrass beds. In the rhizosphere, Sicyoidochytrium, Stellarchytrium and Labyrinthula were enriched, whereas unclassified Labyrinthulomycetes and Thraustochytriaceae lineages prevailed in seawater and specific leaf samples. Notably, a substantial proportion of sequences corresponded to unclassified lineages, potentially representing uncultured “seagrass-associated” taxa. Compared with previous reports, our study revealed both a significantly higher abundance of Stellarchytrium and a remarkably greater proportion of unclassified lineages, suggesting unique features of Labyrinthulomycetes communities in the Caofeidian seagrass ecosystem. These findings provide new insights into the ecological roles of Labyrinthulomycetes in seagrass beds and offer an important reference for future taxonomic and functional studies of this group. Full article

Microplastic (MPL) and nanoplastic (NPL) contamination in soils is widespread, impacting soil invertebrates, microbial communities, and soil–plant systems. Here, we compiled the information from 100 research articles from 2018 onwards to enhance and synthesize the status quo of MPLs’ and NPLs’ impacts on such groups. The effects of these pollutants depend on multiple factors, including polymer composition, size, shape, concentration, and aging processes. Research on soil invertebrates has focused on earthworms and some studies on nematodes and collembolans, but studies are still limited to other groups, such as mites, millipedes, and insect larvae. Beyond soil invertebrates, plastics are also altering microbial communities at the soil–plastic interface, fostering the development of specialized microbial assemblages and shifting microbial functions in ways that remain poorly understood. Research has largely centered on bacterial interactions with MPLs, leaving understudied fungi, protists, and other soil microorganisms. Furthermore, MPLs and NPLs also interact with terrestrial plants, and their harmful effects, such as adsorption, uptake, translocation, and pathogen vectors, raise public awareness. Given the complexity of these interactions, well-replicated experiments and community- and ecosystem-level studies employing objective-driven technologies can provide insights into how MPLs and NPLs influence microbial and faunal diversity, functional traits, and soil ecosystem stability. Full article

Integrated aquaculture, centered around polyculture involving multiple species, is a typical practice for the sustainable development of the aquaculture industry, capable of enhancing resource utilization efficiency, environmental stability, and overall productivity through establishing symbiotic interactions among species. This study employed multi-amplicon high-throughput sequencing to assess the ecological impacts of two polyculture methods involving river crabs on sediment bacteria, fungi, and protists. One method involved polyculturing river crabs with mandarin fish, silver carp, and the stone moroko (SPC), and the other involved polyculturing river crabs with only mandarin fish and silver carp (SMC). The results showed that, compared to the SMC group, the SPC group remarkably increased the Chao1 index of bacterial communities in pond sediment and decreased the Pielou_J index of protists. The relative abundances of all fungal phyla and most dominant bacterial and protistan phyla (top 10 in relative abundance) in the SPC group were considerably different from those in the SMC group. In the co-occurrence networks of bacterial, fungal, and protistan communities, the numbers of edges and nodes were higher in the SPC group than in the SMC group, and the habitat niche breadth of bacterial community was also notably increased in the SPC group. The levels of total carbon (TC), total nitrogen (TN), and phosphates within pond sediment in the SPC group were obviously lower than those in the SMC group, and were significantly correlated with the microbial communities, with TC being identified as the primary contributor driving changes in the microbial communities. All the findings collectively demonstrate that the polyculture of river crabs with mandarin fish, silver carp, and the stone moroko enhances the stability of bacterial, fungal, and protistan communities in sediment and enhances resource utilization efficiency in aquaculture, thereby preventing the environmental risks associated with excessive nutrient accumulation in sediment. Polyculture systems integrating river crabs with mandarin fish, silver carp, and the stone moroko represent a sustainable aquaculture model with significant ecological benefits. Full article

Coinfections in COVID-19 patients can worsen disease severity by enhancing SARS-CoV-2 replication and proinflammatory cytokine levels. This study analyzes the characteristics of coinfected COVID-19 patients across the pandemic and their association with in-hospital mortality. We retrospectively examined data from 351 COVID-19 patients hospitalized in a Spanish secondary hospital between March 2020 and February–March 2021. Nasopharyngeal swabs from 340 patients were analyzed using multiplex RT-PCR to identify 26 respiratory pathogens. A total of 136 patients were coinfected with 191 bacteria (100 Gram-negative and 91 Gram-positive), 20 viruses, 18 fungi, and 1 protist. In 2021, empirical cephalosporin use increased (p = 0.009). The incidence of enterococcal coinfections tripled from 2020 to 2021 (p < 0.001). In 2021, a greater proportion of patients experienced urine (p = 0.001) and bloodstream (p = 0.010) coinfections. In 2020, there was one bloodstream infection, while in 2021, there were seven, with half of them being fatal. Coinfected patients experienced longer hospital stays and higher odds of long COVID (p < 0.001; p = 0.014; p = 0.045). Non-respiratory coinfections in 2021 correlated with increased mortality (p = 0.002). Antimicrobial resistance remained stable (p = 0.149). The rise in cephalosporin use correlated with increased Enterococcus infections, notably bloodstream infections, which were linked to mortality (p = 0.016). In 2021, coinfections were linked to prolonged hospital stays and an increased risk of mortality in our patient cohort. Full article

Salinity is a key environmental factor regulating lipid metabolism in marine oleaginous protists. This study examined the impact of NaCl concentration on growth, glucose utilization, and lipid biosynthesis in Thraustochytrium sp. ATCC 26185. Moderate salinity (20 g/L) enhanced biomass and glucose uptake, while high salinity (45 g/L) induced osmotic stress yet significantly promoted squalene accumulation (17.27 mg/g), a 3.26-fold increase compared with 0 g/L NaCl (5.29 mg/g). Integrated transcriptomic and metabolomic analyses revealed that salinity-dependent activation of glycolysis, the TCA cycle, and the pentose phosphate pathway increased cellular ATP, NADH, and NADPH levels. Under salt stress, the mevalonate (MVA) pathway was transcriptionally upregulated, with key enzymes, including ACAT, HMGR, and IDI, showing marked induction, which supports enhanced carbon flux toward squalene biosynthesis. Despite SQS downregulation, squalene accumulation increased, likely due to elevated precursor availability and reduced flux to downstream sterol pathways. Concurrently, high salinity repressed expression of ACC, FAS-α, and FAS-β, reducing saturated fatty acid levels, while upregulation of PKSB-favored polyunsaturated fatty acid (PUFA) synthesis. These findings suggest that high-salt stress triggers transcriptional reprogramming, redirecting acetyl-CoA from fatty acid synthesis toward squalene and PUFA production. This study offers new insights into the metabolic plasticity of thraustochytrids and highlights salinity modulation as a promising strategy for enhancing high-value lipid yields in marine biotechnology. Full article

Resolving the eukaryotic tree of life (eToL) remains a fundamental challenge in biology. Much of eukaryotic phylogenetic diversity is occupied by unicellular microbial eukaryotes (i.e., protists). Among these, the phylogenetic positions of a significant number of lineages remain unresolved due to limited data and ambiguous traits. To address this issue, we introduce the term “PUPAs” (protists with uncertain phylogenetic affiliations) to collectively describe these lineages, instead of using vague or inconsistent labels, such as incertae sedis or orphan taxa. Historically, protists were classified based solely on morphological features, and many with divergent cell structures were left unplaced in the eToL. With the advent of sequence-based approaches, the phylogenetic affiliations of some PUPAs have been clarified using molecular markers, such as small subunit ribosomal DNA. The combination of technological progress and continuous efforts to cultivate diverse protists, including PUPAs and novel protists, now enables phylogenetic analyses based on hundreds of proteins, providing their concrete placements in the eToL. For example, these advances have led to the discovery of new deep-branching lineages (e.g., Hemimastigophora), the resolution of relationships among major groups (e.g., Microheliella, which linked Cryptista and Archaeplastida), and insights into evolutionary innovations within specific clades (e.g., Glissandra). In this review, we summarize current consensus in eukaryotic phylogeny and highlight recent findings on PUPAs whose phylogenetic affiliations have been clarified. We also discuss a few lineages for which the phylogenetic homes remain unsettled, the evolutionary implications of these discoveries, and the remaining challenges in resolving the complete eToL. Full article

Research is required to determine whether the coinfections by Fasciola spp. and other parasite species result from poor rural hygiene or reflect underlying epidemiological patterns and causes. Therefore, the role of fascioliasis is analyzed concerning coinfection complexity, risk of multiparasitism, parasite associations, pathogenic implications and their multifactorial causes. Helminth and protozoan coinfections are studied in 2575 previously untreated individuals from four rural hyperendemic areas (Northern Bolivian Altiplano, Peruvian Altiplano and Cajamarca valley, and the Egyptian Nile Delta). This cross-sectional study was conducted from January 2011 to December 2023. Coinfections were coprologically assessed by the merthiolate–iodine–formalin and formol–ether concentration techniques. Infection intensity was measured as eggs/gram of feces (epg) with the Kato–Katz technique. Parasite and coinfection prevalences were stratified by age, sex and geographical location. High mixed infections, fascioliasis prevalences and very low non-coinfected Fasciola-infected subjects were associated with the following regions: Bolivian Altiplano, 96.5%, 16.8% and 3.5%; Peruvian Altiplano, 100%, 24.6% and 0%; Cajamarca valley, 98.7%, 21.4% and 1.8%; Nile Delta, 84.1%, 13.0% and 15.9%. Transmission routes and human infection sources underlie fascioliasis associations with protozoan and other helminth infections. Prevalence pattern of protozoan–helminth coinfections differed between Fasciola-infected individuals and individuals not infected with Fasciola, presenting higher prevalences in individuals with fascioliasis. Multiparasitism diagnosed in Fasciola-infected subjects included coinfections by up to nine parasite species, eight protozoan species, and five helminth species. The most prevalent pathogenic protozoan was Giardia intestinalis. The most prevalent helminth species differ according to environmental conditions. Several parasites indicate fecal environmental contamination. When the fascioliasis burden increases, the total number of parasite species also increases. The fascioliasis risk increases when the total helminth species number/host increases. Fasciola-infected subjects may present a modification in the clinical phenotypes of coinfecting parasitic diseases. Fascioliasis coinfection factors include transmission ways and immunological, environmental and social aspects. Coinfections must be considered when assessing the health impact of fascioliasis, including the analysis of the fascioliasis effects on malnutrition and physical/intellectual child development. Fascioliasis-control schemes should, therefore, integrate control measures mainly against other helminthiases. Full article

Silica-based materials are recognized as effective functional materials across diverse industrial fields, including biomedicine (e.g., drug delivery systems (DDS), biosensors, and tissue engineering), owing to their excellent stability and physicochemical characteristics. Among them, diatom biosilica (DB), which constitutes a major part of aquatic biomass, recently gained significant attention as a valuable biomaterial following breakthroughs in its innovative surface structure, superior biocompatibility and multifunctionality. Therefore, DB is emerging as an alternative to synthetic materials used in the biomedical field. This review comprehensively examines the diverse biological properties of DB, followed by an analysis of harvesting and purification strategies. Then, the current application status of DB in two principal biomedical domains, DDS and biosensors, is evaluated. Furthermore, the convergence of these domains into theragnostic applications addresses a significant unmet clinical need for simultaneous therapeutic intervention and diagnostic monitoring, positioning DB as a transformative biomaterial solution. The unique combination of natural hierarchical architecture, tunable surface properties, and excellent biocompatibility make DB promising candidates for next-generation integrated biomedical platforms to address the growing demand of personalized medicine and precision healthcare solutions. Full article

Blastocystis spp. is an enteric protist that is present worldwide. Despite being discovered a century ago, there is still much to be learned about its pathogenicity and transmission. Different subtypes (ST) of Blastocystis spp. have been identified in various hosts, including humans, birds, and insects, and there is potential for zoonotic transmission through contact between humans and animals. The prevalence of Blastocystis spp. in humans and macaques in Singapore was understudied, and the findings revealed a significant prevalence of the parasite, with rates of 90% and 100% observed in each respective Macaca fascicularis population 1 and 2, with main subtypes (ST1, ST2, ST3, and ST5). Using metagenomics, the different subtypes of Blastocystis spp. (comprising ST2, ST3, and ST17) were identified in a healthy Singaporean cohort. Additionally, seven incidental findings of Blastocystis spp. were discovered in human patients with other gut parasites, including two ST1, two ST2, two ST3, and one ST8. Several factors such as diet or reverse zoonotic transmission are suggested to play a role in Blastocystis sp. subtype distribution. Full article

Obligate symbionts often exhibit some degree of co-speciation with their hosts. One prominent example is the symbiosis between termites and their wood-feeding hindgut protists. This symbiosis is mutually obligate, vertically inherited by anal feeding, and it predates the emergence of termites from their cockroach ancestors. Termites and their symbiotic protists might therefore be expected to have congruent phylogenies, but symbiont loss, transfer, and independent diversification can impact the coevolutionary history to varying degrees. Here, we have characterized the symbiotic protist communities of eight Neoisoptera species from three families in order to gauge the phylogenetic congruence between each lineage of protists and their hosts. Using microscopy and 18S rRNA gene sequencing of individually isolated protist cells, we identified protists belonging to the Parabasalia genera Pseudotrichonympha, Holomastigotoides, Cononympha, and Cthulhu. Pseudotrichonympha were present in all of the investigated termites, with a strong pattern of codiversification with hosts, consistent with previous studies. The phylogeny of Holomastigotoides indicates several instances of diversification that occurred independently of the hosts’ diversification, along with lineage-specific symbiont loss. Cononympha occurs only in Heterotermitidae and Psammotermes. Surprisingly, the small flagellate Cthulhu is widespread and exhibits cophylogeny with its hosts. This study demonstrates that different symbiont lineages can show different coevolutionary patterns, even within the same host. Full article

Kleptoplastidy is a nutrition mode in which cells of protists and some multicellular organisms acquire, maintain, and exploit chloroplasts of prey algae cells as photosynthesis reactors. It is an important aspect of the mixotrophic feeding strategy, which plays a role in the formation of harmful algae blooms (HABs). We developed a new mathematical model, in which kleptoplastidy is regarded as a mechanism of enhancing mixotrophy of protists. The model is constructed using three thought (theoretical) experiments and the concept of biological time. We propose to measure the contribution of kleptoplastidy to mixotrophy using a new ecological indicator: the kleptoplastidy index. This index is a function of two dimensionless variables, one representing the ratio of photosynthetic production of acquired chloroplasts versus native chloroplasts, and the other representing the balance between autotrophic and heterotrophic feeding modes. The index is tested by data for the globally distributed, bloom-forming potentially toxic mixotrophic dinoflagellates Prorocentrum cordatum. The model supports our hypothesis that kleptoplastidy can increase the division rate of algae significantly (by 40%), thus boosting their population growth and promoting blooms. The proposed model can contribute to advancements in ecological modeling aimed at forecasting and management of HABs that deteriorate marine coastal environments worldwide. Full article

Protists represent a major component of eukaryotic diversity within the soil microbiome, playing critical roles in mediating carbon and nitrogen cycling and influencing nutrient availability and soil health. Their diversity is shaped by multiple factors, including temperature, pH, organic matter content, and land use. In this study, we investigated the protist diversity in rhizosphere soils from both wild and cultivated date palm varieties. Our results identified nitrate, nitrite, calcium, and carbon content as key soil factors significantly correlated with protist diversity. Only 9.2% (42) of operational taxonomic units (OTUs) were shared across all soil samples, suggesting that these taxa possess traits enabling adaptation to extreme environmental conditions. The dominant protist families belonged to Rhizaria, Alveolata, Amoebozoa, and Archaeplastida, primarily comprising bacterial consumers, alongside taxa from Stramenopiles, Opisthokonta, Hacrobia, and Excavata. At the class level, Filosa-Sarcomonadea, Colpodea, Variosea, Tubulinea, and Chlorophyceae were the most abundant. Filosa-Sarcomonadea and Colpodea were positively correlated with bacterial and fungal genera, suggesting their role as consumers, while Variosea showed a negative correlation with bacteria, reflecting predator-prey dynamics. Notably, the protist community composition in wild date palm rhizosphere soils was distinct from that in cultivated soils, with Opisthokonta being particularly abundant, likely reflecting adaptation to drought conditions. Overall, this study highlights the significant differences in protist diversity and community structure between wild and cultivated date palm ecosystems. Full article

Understanding the processes that drive microbial community assembly is a fundamental question in ecology, with important implications for predicting community responses to environmental disturbances. River ecosystems are under growing pressure from human disturbances, jeopardizing their ecological functions. Here, we investigated bacterial and protistan communities along the Yujiang River using environmental DNA metabarcoding. Bacterial communities exhibited significantly greater alpha diversity and broader habitat niches compared to protists. Additionally, a negative correlation was found between alpha diversity and niche breadth for both groups. Protistan communities exhibited significantly higher beta diversity (Bray–Curtis distance) than bacterial communities, with species turnover being the principal factor driving the variations in both communities. Null model results indicated that heterogeneous selection primarily structured bacterial communities, while stochastic processes (drift) mainly governed protist communities. Redundancy analysis and Mantel tests showed significant associations between environmental factors (e.g., temperature and pH) and bacterial community composition. Moreover, the longitude of sampling sites was linked to spatial variations in both bacterial and protistan communities. Further analyses, including distance-decay patterns, variation partitioning, and multiple regression on distance matrices, demonstrated that bacterial communities were driven by both environmental and spatial factors, while protist communities exhibited a stronger response to spatial factors. These results enhance our understanding of microbial community assembly in river ecosystems and provide valuable insights for the conservation and sustainable management of freshwater systems. 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