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At least 37 records · Page 2Linked to original sources

PubMed2025

Host-Associated Genetic Differentiation in the Face of Ongoing Gene Flow: Ecological Speciation in a Pathogenic Parasite of Freshwater Fish.

Adaptive evolution in response to varying environments, leading to population divergence, is among the most intriguing processes of speciation. However, the extent to which these adaptive processes effectively drive population divergence amidst ongoing gene flow remains controversial. Our study addresses this by analyzing population genetic structure, gene flow, and genomic divergence between lineages of a tapeworm parasite (Ligula intestinalis) isolated from sympatric fish hosts. This parasite, which must overcome host immunological defenses for successful infection, significantly impacts host health. Utilizing genome-wide Single Nucleotide Polymorphisms (SNPs) and transcriptome data, we investigated whether host species impose distinct selection pressures on parasite populations. Genetic clustering analyses revealed clear divergence, with parasites from bream (Abramis brama) forming a distinct genetic cluster separate from those infecting roach (Rutilus rutilus), rudd (Scardinius erythrophthalmus), and bleak (Alburnus alburnus). Demographic modeling indicated isolation with continuous gene flow as the most plausible scenario for this divergence. Selection analyses identified 896 SNPs under selection, displaying low to moderate nucleotide diversity and genetic divergence compared with neutral loci. Transcriptome profiling supported these findings, revealing distinct gene expression profiles between parasite populations. Examination of selected SNPs and differentially expressed genes identified candidate genes linked to immune evasion mechanisms, potentially driving ecological speciation. This research highlights the interplay of host specificity, population demography, and disruptive selection in ecological speciation. By dissecting genomic factors, our study improves the understanding of mechanisms facilitating population divergence despite ongoing gene flow.

Animals↗

PubMed2025

Agricultural land use and ensuing eutrophication both shape parasitic trematode communities in rural African lakes.

Land use is a major driver of biodiversity loss, but how it impacts parasite communities is scarcely documented. Crater lakes and their catchments in rural western Uganda greatly vary in their intensity of anthropogenic disturbance, thus providing an opportunity to assess the effects of land use on snail-borne parasitic trematodes. We applied state-of-the-art molecular biomonitoring to 2385 Bulinus tropicus snails from 34 lakes to detect and genotype trematode infections. The 45 trematode taxa recovered infect a wide range of final vertebrate hosts, and some can cause health burdens of significant public importance. Using constrained ordinations and generalized additive models, we found that B. tropicus reaches peak abundance in lakes with catchments partly under agriculture, whereas trematode infections increase with B. tropicus abundance and peak at intermediate aquatic productivity. Trematode diversity also increases with aquatic productivity, levelling off only in the most productive lakes. These relationships likely reflect the higher abundance and variety of final hosts sustained by more productive lakes. Finally, we found that land use affects trematode community composition, with more livestock parasites and less bird parasites occurring in agricultural catchments. Our results indicate that both land use and lake eutrophication affect the distribution of hotspots for parasitic disease transmission.

Lakes↗

PubMed1975

[Ultrastructural localization of alkaline phosphatase and ATP-ase in cyst stages of Sarcocystis tenella (Sporozoa, Coccidia) parasitic in the esophagus of sheep (author's transl)].

The activity of adenosine triphosphatase and alkaline phosphatase was investigated at the fine structural level in the cyst stages of Sarcocystis tenella parasitic in the esophagus of sheep. Alkaline phosphatase reaction was observed along the outer membrane of the parasite's pellicle. The enzymatic activity was much higher on the surface of metrocytes than that of zoites, which proved to be infectious. No reaction was noted in the interior of the parasites. However, a significant amount of alkaline phosphatase activity occurred along the inner surface of the 25 nm thick primary layer of the cyst wall. No evidence of the reaction of this enzyme was seen in the secondary cyst wall, which consisted of degenerated host cells. ATP-ase activity was found in a considerable degree along the primary cyst wall (=directly limiting the cyst's interior), whereas the ground-substance of the cyst, surrounding the parasites, is free of deposits. In the parasites ATP-ase was localized in the endoplasmic reticulum, in the perinuclear space, and between the two inner membranes of the three-layered pellicle. Only rarely a slight reaction was seen in the mitochondria of the metrocytes, which are the reproductive cells. The other organelles typical for S. tenella were free of ATP-ase. The results indicate that the enzymes studied participate in the growing process of the cysts, in which finally the infectious zoites remain in a more or less inactive state. The localizations of the enzymes corresponded with the results known from metazoa.

Adenosine Triphosphatases↗

PubMed2026

From Sequential Gland Replacement to Recurrent Gland Coordination: A Comparative Framework for Subventral and Dorsal Oesophageal Gland Effectors Across Plant-Parasitic Nematode Lifestyles.

Plant-parasitic nematodes manipulate host tissues through stylet-secreted gene products synthesised principally in two subventral and one dorsal oesophageal gland. Earlier reviews have catalogued effector repertoires, described feeding-site formation, and explained how individual effectors modify host defence, development, and metabolism. However, the temporal coordination of the gland cells themselves has not been comparatively synthesised across parasitic lifestyles. This review therefore advances a gland-centred, lifestyle-dependent framework. In sedentary endoparasites, available evidence supports a pronounced developmental transition: subventral gland products dominate penetration and migration, whereas dorsal gland products become increasingly important during feeding-site initiation and maintenance. Migratory endoparasites repeatedly penetrate, migrate, and feed without establishing permanent feeding cells; their gland activity is consequently predicted to be recurrent and overlapping rather than a one-way replacement. Ectoparasites likewise require behaviour-dependent coordination during repeated probing and external feeding, although direct gland localisation evidence remains limited. We integrate gland origin, secretion chemistry, infection stage, and parasitic behaviour across root-knot, cyst, citrus, false root-knot, lesion, burrowing, and ectoparasitic nematodes. The synthesis distinguishes experimentally demonstrated gland localisation from evidence-weighted inference and formulates testable predictions for comparative gland transcriptomics, spatial expression, and functional silencing. This framework also identifies gland activation, secretion, and stage-critical products as targets for RNA interference, genome editing, resistance breeding, and sustainable nematode management. The principal novelty is therefore not another catalogue of nematode effectors, but a comparative model explaining when and why subventral and dorsal glands exchange, retain, or alternate their functions across contrasting parasitic lifestyles.

dorsal gland↗

PubMed1976

[Changes in the blood pictureof the red goat of Maradi as a function of its gastrointestinal parasitism].

Numerous "chèvres de Maradi" are bred in Republique du Niger (cap. Niamey), 2 - 10(+6) numbered in 1973. This rustic ruminant is often very parasitized by intestinal nematodes and sporozoa. The most frequent genera are Bunostomum (55%), Trichostrongylus (40%), Strongyloides (27%), Oesophagostomum and Haemonchus (20%), sometimes Moniezia or Stilesia, coccidiosis being endemic and very pathogenic, Eimeria (70%). Polyparasitism is a "modus vivendi" between the host and these various parasites. All modification of the number or the kind of parasites (prevalence of one or two genera) involves a variation of the differential leucocyte count (anthelmintic cure for example). When the normal leucocyte count is 18 to 22 - 10(+3) per mm3, whose neutrophils: 40.73%; acidophils: 2%; basophils: 0.28%; monocytes: 11.28%; lymphocytes (small and big forms): 45.71%, a tapeworm parasitism by adults (Moniezia or Stilesia) or by peritoneal larvae (Cysticercus sp.) involves a light eosinophilia (8%), in morbid cases of coccidiosis, neutrophilia prevails (70%), and a polyparasitism with nematodes and Eimeria is characterized by monocytosis and neutrophilia, the polynuclear eosinophils being very rare. These observations show the necessity to elaborate simultaneously two cures: the first with an anthelmintic product, the second against coccidia, to avoid an uncertain Eimeria proliferation after the nematode destruction. In African breeding conditions, where polyparasitism is very frequent, such a therapeutic schedule is recommended.

Animals↗

PubMed1979

Freeze fracture studies on the interaction between the malaria parasite and the host erythrocyte in Plasmodium knowlesi infections.

The freeze fracture technique has been used to study the internal cyto-architecture of the surface membranes of the parasite and erythrocyte in Plasmodium knowlesi infections. Six fracture faces, derived from the plasma membrane and 2 pellicular membranes, have been identified at the surface of the free merozoite. The apposed leaflets of the 2 pellicular membranes show the characteristic features of E fracture faces, a result compatible with the view that the pellicular membranes line a potential cisterna. There is evidence to suggest that there may be changes in the distribution and density of the integral proteins in the merozoite plasma membrane at invasion. Furthermore, vesicles consisting of stacked membranes occur within and around the erythrocyte invagination at invasion; it is suggested that these vesicles are released from the merozoite rhoptries. Formation of the parasitophorous vacuole is accompanied by dramatic changes in the density and distribution of intra-membraneous particles (IMP) in the vacuolar membrane. Initially there is a great reduction in particle numbers, but subsequently the particles reappear and show reversed polarity. The possible causes and implications of these changes are discussed. The intra-erythrocytic parasite synthesizes new transmembrane proteins as development proceeds, and the trophozoite and schizont stages of development are characterized by the appearance of circular, particle-free regions in the parasite plasmalemma. There is a decrease in the density of transmembrane proteins in the erythrocyte plasma membrane during parasite maturation, and the P face IMP show the characteristic features of aggregation.

Animals↗

PubMed2025

Genomic resources for comparative analyses of obligate avian brood parasitism.

Examples of convergent evolution, wherein distantly related organisms evolve similar traits, including behaviors, underscore the adaptive power of natural selection. In birds, obligate brood parasitism, and the associated loss of parental care behaviors, has evolved independently in seven different lineages, though little is known about the genetic basis of the complex suite of traits associated with this rare life history strategy. We generated genome assemblies for ten brood parasitic species plus eight species representatives of their parental/nesting outgroups. This includes nine long-read chromosome-level assemblies, with scaffold N50 sizes ranging from 38.1 to 72.6 MB, and gene representation completeness measures >97%. Leveraging this new catalog of avian genomes, we constructed clade-level alignments that reveal variation in chromosomal synteny, provide first-time or improved annotations of protein-coding and non-coding genes, and define cross-species ortholog reference sets. We also refine estimates for the timing of the seven independent origins of brood parasitism, ranging from recent events such as 1.6 to 4.5 million years ago in Molothrus cowbirds to much earlier origins over 30 million years ago in two of the three cuckoo lineages. These genomic resources lay the foundation for investigating the genetic and genomic underpinnings of brood parasitism, including the loss of parental care, shifts in mating systems, perhaps resulting in heightened sperm competition, elevated annual fecundity, improved spatial cognition related to nest-finding, and the diverse adaptations shaped by intense coevolution with host species.

assemblies↗

PubMed1975

A survey of intestinal parasitism in a community on the Pan American Highway route in eastern Panama.

A survey of intestinal parasitism was conducted at Yaviza, a town in eastern Panama's Province of Darien. Single stool specimens from 202 persons, representing 11 percent of the town's total population, were examined. In all, 181 (90 per cent) of the specimens examined were found positive for one or more potentially pathogenic parasites. The most common parasite found was Trichuris trichiura, which was observed in 80 per cent of the samples. Others were Ascaris lumbricoides, in 62 per cent of the samples; hookworm, in 41 per cent; Entamoeba histolytica, in 16 per cent; Stronhyloides stercoralis, in 7 per cent; Giardia lamblia, in 5 per cent; and Hymenolepis diminuta, in 0.5 per cent. The aim of the survey was to gather baseline data on parasite prevalence before the Pan American Highway passes through this area. Construction of the highway is producing marked environmental change. in eastern Panama, and it is anticipated that the date from the survey will prove useful in later efforts to assess the health impact of that change.

Adolescent↗

PubMed2026

Identification of circulating parasite and host biomarkers in the serum proteome of Trypanosoma vivax-infected sheep under immunosuppression.

Bovine trypanosomiasis, caused by Trypanosoma vivax, presents a major threat to livestock health, primarily due to the lack of efficient field diagnostic tools. This study aimed to identify potential parasite and host-derived biomarkers through a longitudinal proteomic analysis of serum from sheep experimentally infected with a T. vivax isolate. Utilizing LC-MS/MS and bioinformatics, 154 proteins were identified, comprising 150 host (Ovis aries) and four pathogen proteins. Principal Component Analysis (PCA) demonstrated a clear separation of samples according to infection stages: Control, Infection (15 parasites/field), and Peak Infection (30-60 parasites/field) Among the parasite proteins, TvY486_0014340, TvY486_0040500, and TvY486_0042480 were identified as candidate antigens for future evaluation. In silico analysis revealed these proteins contain multiple B-cell epitopes with no cross-reactivity to related Trypanosoma species, supporting their potential for immunodiagnostic development. Additionally, three host proteins-folate receptor 3 (FOLR3) and complement components C1QA and C1QC-were significantly modulated across all infection phases. The upregulation of FOLR3 likely reflects a compensatory response to parasite-induced anemia, while the downregulation of C1Q components suggests immune evasion strategies. These findings highlight specific parasite antigens and host regulatory patterns that may serve as candidate biomarkers for the diagnosis and monitoring of T. vivax infection, facilitating the development of improved point-of-care assays.

Animals↗

PubMed2026

Molecular DNA enrichment methods for parasite genomic sequencing in clinical samples: a systematic review.

Parasitic diseases such as malaria, Chagas disease, leishmaniases, and helminthiases are major causes of sickness and death in low- and middle-income countries. The high genetic diversity of these pathogens affects virulence, immune evasion, and diagnostic accuracy. Although Whole Genome Sequencing (WGS) is a powerful tool for tracking genetic variants and drug resistance, low parasitemia and the predominance of host DNA limit its application to clinical samples. This study systematically reviewed molecular strategies to improve the recovery of parasite DNA from clinical samples, following PRISMA 2020 guidelines and registered in PROSPERO. Searches of PubMed, Scopus, Web of Science, and LILACS up to December 2025 identified 20 eligible studies, most of which focused on protozoa, particularly Plasmodium spp. The main approaches included hybridization capture, selective whole-genome amplification, host DNA depletion, and in silico enrichment via adaptive sampling. Overall, no single method is suitable for all parasites analyzed; the optimal approach depends on the pathogen, sample type, and research objective. The review emphasizes that parasite DNA enrichment is essential for enabling WGS in clinical settings, underscoring the need for protocol standardization and cost-effectiveness analyses to support public health genomic surveillance.

Adaptive sampling↗

PubMed2024

A pyruvate transporter in the apicoplast of apicomplexan parasites.

Pyruvate lies at a pivotal node of carbon metabolism in eukaryotes. It is involved in diverse metabolic pathways in multiple organelles, and its interorganelle shuttling is crucial for cell fitness. Many apicomplexan parasites harbor a unique organelle called the apicoplast that houses metabolic pathways like fatty acid and isoprenoid precursor biosyntheses, requiring pyruvate as a substrate. However, how pyruvate is supplied in the apicoplast remains enigmatic. Here, deploying the zoonotic parasite Toxoplasma gondii as a model apicomplexan, we identified two proteins residing in the apicoplast membranes that together constitute a functional apicoplast pyruvate carrier (APC) to mediate the import of cytosolic pyruvate. Depletion of APC results in reduced activities of metabolic pathways in the apicoplast and impaired integrity of this organelle, leading to parasite growth arrest. APC is a pyruvate transporter in diverse apicomplexan parasites, suggesting a common strategy for pyruvate acquisition by the apicoplast in these clinically relevant intracellular pathogens.

Apicoplasts↗

PubMed2005

Linkage group selection: rapid gene discovery in malaria parasites.

The identification of parasite genes controlling phenotypes such as drug resistance, virulence, immunogenicity, and transmission is vital to malaria research. Classical genetic methods have achieved these goals only rarely and with difficulty. We describe here a novel genetic method, Linkage Group Selection (LGS), which achieves rapid de novo location of genes encoding selectable phenotypes of malaria parasites. A phenotype-specific selection pressure is applied to the uncloned progeny of a genetic cross between two malaria parasites that differ in the relevant phenotype. Selected and unselected progeny are analyzed using genome-wide quantitative genetic markers. Markers of the "sensitive" parent, which are reduced after selection, are sequenced and located in genomic databases. They are expected to be closely linked to gene(s) determining the phenotype under selection. We have validated LGS with the rodent malaria parasite Plasmodium chabaudi chabaudi using a phenotype, pyrimethamine resistance, whose controlling gene, that encoding dihydrofolate reductase (dhfr), is known. We show that molecular markers closely linked to dhfr, and only those linked to this gene, were reduced or removed by pyrimethamine treatment in accordance with the expectations of LGS.

Animals↗

PubMed1978

Bovine cryptosporidiosis: a transmission and scanning electron microscopic study of some stages in the life cycle and of the host-parasite relationship.

Transmission and scanning electron microscopy of the ileal mucosae from 12 calves infected with Cryptosporidium sp. showed cryptosporidia free in the lumen and attached to epithelium. The attached parasites were interpreted to be extracellular and adherent to the microvillous border of epithelial cells. Stages of the organism included crescentic-free merozoites, trophozoites, schizonts, gametes and oocysts. Attached parasites were detected chiefly at villous tips and all stages were present on a single villus. Attachment sites were characterized by absence or disintegration of microvilli, disorganization of the terminal web and development of a specialized attachment zone. There were increased numbers of lysosomes and irregularities in the nuclear membrane of parasitized epithelial cells. It was concluded that cryptosporidia exist in bovine intestine as extracellular parasites and cause epithelial changes that in turn probably cause or contribute to diarrheal disease.

Animals↗

PubMed2025

RNG2 tethers the conoid to the apical polar ring in Toxoplasma gondii to enable parasite motility and invasion.

The conoid is a dynamic, tubulin-based structure conserved across the Apicomplexa that undergoes extrusion during egress, gliding motility, and invasion in Toxoplasma gondii. This organelle traverses the apical polar ring (APR) in response to calcium waves and plays a critical role in controlling parasite motility. While the actomyosin-dependent extrusion of the conoid is beginning to be elucidated, the mechanism by which it remains apically anchored to the APR is still unclear. RNG2, a protein localized to both the conoid and the APR, has emerged as a strong candidate for mediating this connection. Biochemical analysis revealed that RNG2 is an unstable protein, undergoing extensive proteolytic cleavage both in the parasite and in heterologous expression systems. Its biochemical properties, with the presence of large coiled-coil domains, likely facilitate the formation of concatenated assemblies, enabling RNG2 to serve as a dynamic and resilient bridge between the conoid and the APR. Using a combination of iterative ultrastructure expansion microscopy and immunoelectron microscopy, we confirmed the localization of RNG2 to the 22 tethering elements bridging the APR and the conoid. Conditional depletion of RNG2 led to the striking detachment of the intact conoid organelle from the APR, supporting an essential role for RNG2 as a tether. Cryo-electron tomography of conoid-less parasites revealed that, in the absence of RNG2, the apical vesicle remains anchored to the plasma membrane, while the rhoptries follow the detached conoid. Although RNG2 depletion only mildly reduces microneme secretion, the parasites are immotile and exhibit impaired rhoptry discharge, highlighting the critical role of proper conoid anchorage in motility and host cell invasion. Comprehensive mutagenesis of RNG2 identified distinct regions responsible for binding to the conoid and the APR, and demonstrated that the full-length, intact protein is essential for bridging these two structures and for its functional activity. Altogether, RNG2 emerges as a pivotal protein that ensures conoid functionality and coordination in Coccidia.

Toxoplasma↗

PubMed1977

[Parasitic calcifications: elements for diagnostic (author's transl)].

Among the radiologic calcifications, those of parasitic etiology are rather commonly found. They are heterotopic dystrophic calcifications, their late apparition in the evolution of the parasitic disease is not subordinate to any metabolic dysfunction. The authors describe the morphologic and the topographic criteria of different parasitic calcifications except the fungic ones and protozoaire. Moreover they state for each parasite some epidemiological, biological and clinical facts which can be helpful for the diagnosis.

Acanthocephala↗

PubMedDate not supplied

[Intensity of parasitic contacts in the colonies of large gerbils under conditions of different population density of the animals and their fleas].

In the period from April to May and September to October of 1967--1973 in the Mujun-Kum a radioactive tracing of great gerbils was carried out. In all 225 tests were conducted. The greatest intensity of parasitic contacts between the animals was noted at their average quantity. Its further rise does not result in the increase of the parasitic relations. If the number of fleas is high the parasitic contacts level even at the relatively low number of great gerbils is usually high enough for a further passing of the plague microbe. If the number of both fleas and great gerbils is low the parasitic relations provide but not always an agent transmission.

Animals↗

PubMed1979

Effects of parasitic infections in pregnant women.

This review focuses on the parasitic diseases which occur frequently in the tropics and which affect pregnant women. Clinical disease of the mother during pregnancy, vertical transmission of parasites and transplacental passage of soluble parasitic antigens are discussed in relation to their immunopathological significance for the fetus. The incidences of congenital malaria, African trypanosomiasis and Chagas' disease are reviewed, together with vertical transmission of filarial infection, involvement of the female genital tract in schistosomiasis, and fulminant colitis due to Entamoeba histolytica infection during pregnancy.

Animals↗

PubMed2026

The genome of Thesium ramosoides (Santalales) reveals evolutionary dynamics associated with parasitism and alpine adaptation.

Plant species adapting to complex environments experience contrasting selection pressures that drive the expansion and contraction of different gene families. However, few studies have investigated simultaneous genomic responses to such diverse selective forces. Here, we generate a high-quality genome assembly for the hemiparasitic plant Thesium ramosoides, the first for the largest genus in the Santalales, and explore the genomic basis underlying the evolution of parasitism and alpine adaptation. Unlike many other parasitic plants, the Thesium genome has not undergone additional rounds of whole-genome duplication, making it particularly tractable for studying gene family evolution. Our analyses reveal substantial loss of photosynthesis-related genes and contraction of biotic defense gene families, likely reflecting adaptation to a hemiparasitic lifestyle and reduced pathogen pressure at high altitudes. The absence of key root hair development genes correlates with the degenerate root hair phenotype observed in this species. Furthermore, hallmarks of high-altitude adaptation include the expansion of gene families involved in responses to hypoxia. Notably, expansion of gene families associated with meristem development is consistent with the presence of below-ground crown buds that enable rapid regeneration after mountain fires. Unexpectedly, we detected tandem duplication and diversification of the strigolactone receptor gene D14, which regulates secondary shoot formation, but not of its ancestral paralog KAI2, which mediates seed germination in response to the smoke-derived compound karrikin. This finding suggests divergent signaling mechanisms underlying fire adaptation across different parasitic plant lineages. By integrating time-series transcriptomic data, we propose a post-fire "defense first, repair later, recovery last" model, in which resources are reallocated from immediate defense to rapid repair and ultimately to long-term recovery, to explain the adaptation of T. ramosoides to fire-prone habitats. Our study provides critical insights into the complex and contrasting genomic dynamics that drive adaptation to multiple co-occurring selection pressures.

Genome, Plant↗