Species-Specific Differences in Heterogonic Development of Serially Transferred Free-Living Generations of Strongyloides planiceps and Strongyloides stercoralis

Approximately 800 million people worldwide are infected with one or more species of skin-penetrating nematodes. These parasites persist in the environment as developmentally arrested third-stage infective larvae (iL3s) that navigate toward host-emitted cues, contact host skin, and penetrate the skin. iL3s then reinitiate development inside the host in response to sensory cues, a process called activation. Here, we investigate how chemosensation drives host seeking and activation in skin-penetrating nematodes. We show that the olfactory preferences of iL3s are categorically different from those of free-living adults, which may restrict host seeking to iL3s. The human-parasitic threadwormStrongyloides stercoralisand hookwormAncylostoma ceylanicumhave highly dissimilar olfactory preferences, suggesting that these two species may use distinct strategies to target humans. CRISPR/Cas9-mediated mutagenesis of theS. stercoralis tax-4gene abolishes iL3 attraction to a host-emitted odorant and prevents activation. Our results suggest an important role for chemosensation in iL3 host seeking and infectivity and provide insight into the molecular mechanisms that underlie these processes.

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Diversity of Aerobic Bacteria Isolated from Oral and Cloacal Cavities from Free-Living Snakes Species in Costa Rica Rainforest

International Scholarly Research Notices ◽

10.1155/2017/8934285 ◽

2017 ◽

Vol 2017 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Allan Artavia-León ◽

Ariel Romero-Guerrero ◽

Carolina Sancho-Blanco ◽

Norman Rojas ◽

Rodolfo Umaña-Castro

Keyword(s):

Costa Rica ◽

Bacterial Infections ◽

Bacterial Species ◽

Ribosomal Database Project ◽

Opportunistic Pathogens ◽

Bacterial Taxonomy ◽

Free Living ◽

16S Rdna Pcr ◽

Animal Bites ◽

Species Specific

Costa Rica has a significant number of snakebites per year and bacterial infections are often complications in these animal bites. Hereby, this study aims to identify, characterize, and report the diversity of the bacterial community in the oral and cloacal cavities of venomous and nonvenomous snakes found in wildlife in Costa Rica. The snakes where captured by casual encounter search between August and November of 2014 in the Quebrada González sector, in Braulio Carrillo National Park. A total of 120 swabs, oral and cloacal, were taken from 16 individuals of the Viperidae and Colubridae families. Samples were cultured on four different media at room temperature. Once isolated in pure culture, colonies were identified with the VITEK® 2C platform (bioMérieux). In order to test the identification provided on environmental isolates, molecular analyses were conducted on 27 isolates of different bacterial species. Specific 16S rDNA PCR-mediated amplification for bacterial taxonomy was performed, then sequenced, and compared with sequences of Ribosomal Database Project (RDP). From 90 bacterial isolates, 40 different bacterial species were identified from both oral and cloacal swabs. These results indicate the diversity of opportunistic pathogens present and their potential to generate infections and zoonosis in humans.

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Factors influencing development of free-living generations of Strongyloides stercoralis

Parasitology ◽

10.1017/s0031182000066804 ◽

1988 ◽

Vol 97 (1) ◽

pp. 129-138 ◽

Cited By ~ 16

Author(s):

K. Shiwaku ◽

Y. Chigusa ◽

T. Kadosaka ◽

K. Kaneko

Keyword(s):

High Temperature ◽

Incubation Temperature ◽

Strongyloides Stercoralis ◽

Test Tube ◽

Paper Test ◽

Free Living ◽

Factors Influencing ◽

Prednisolone Treatment ◽

Duration Of Infection ◽

Incubation Temperatures

SUMMARYThe effects of duration of infection and of temperature and nourishment in cultures on development of free-living generations of Strongyloides stercoralis were studied quantitatively. Rhabditiform larvae, 228–353 μm long, were collected from infected dogs with or without prednisolone treatment using the Baermann apparatus. Cultures were carried out by the filter paper test-tube method under the following conditions: incubation temperature 15–40°C and faecal dilution 1:0–1:16. Rhabditiform larvae developed predominantly to free-living females at incubation temperatures of 15–30°C and low faecal dilutions, but filariform larvae appeared mainly under extreme conditions such as high temperature. Recovery rates of filariform larvae were inversely related to those of females. It was remarkable that high temperature, but not low faecal dilution, affected development of filariform larvae. Although the appearance of free-living males was constant in various environmental conditions, the present study indicated an increase in free-living males with the duration of infection. Thus, it seems that free-living males are already fixed as male in the egg stage, and potential female rhabditiform larvae differentiate into free-living females or filariform larvae depending on environmental factors. There is no marked difference in the development of rhabditiform larvae into filariform larvae in either the immunosuppressed dog or the intact dog.

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Comparative Genomics of Gene Expression in the Parasitic and Free-Living Nematodes Strongyloides stercoralis and Caenorhabditis elegans

Genome Research ◽

10.1101/gr.1524804 ◽

2004 ◽

Vol 14 (2) ◽

pp. 209-220 ◽

Cited By ~ 70

Author(s):

M. Mitreva

Keyword(s):

Gene Expression ◽

Caenorhabditis Elegans ◽

Comparative Genomics ◽

Strongyloides Stercoralis ◽

Free Living

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Exposure to dexamethasone modifies transcriptomic responses of free-living stages of Strongyloides stercoralis

PLoS ONE ◽

10.1371/journal.pone.0253701 ◽

2021 ◽

Vol 16 (6) ◽

pp. e0253701

Author(s):

Rutchanee Rodpai ◽

Oranuch Sanpool ◽

Tongjit Thanchomnang ◽

Pokkamol Laoraksawong ◽

Lakkhana Sadaow ◽

...

Keyword(s):

Developmental Process ◽

Endocrine System ◽

Strongyloides Stercoralis ◽

Differentially Expressed ◽

The Novel ◽

Rna Seq ◽

Free Living ◽

Risk Of Mortality ◽

Dependent Protein ◽

Embryonic Morphogenesis

Hyperinfection and disseminated infection by the parasitic nematode Strongyloides stercoralis can be induced by iatrogenic administration of steroids and immunosuppression and lead to an elevated risk of mortality. Responses of free-living stages of S. stercoralis to the therapeutic corticosteroid dexamethasone (DXM) were investigated using RNA-seq transcriptomes of DXM-treated female and male worms. A total of 17,950 genes representing the transcriptome of these free-living adult stages were obtained, among which 199 and 263 were differentially expressed between DXM-treated females and DXM-treated males, respectively, compared with controls. According to Gene Ontology analysis, differentially expressed genes from DXM-treated females participate in developmental process, multicellular organismal process, cell differentiation, carbohydrate metabolic process and embryonic morphogenesis. Others are involved in signaling and signal transduction, including cAMP, cGMP-dependent protein kinase pathway, endocrine system, and thyroid hormone pathway, as based on Kyoto Encyclopedia of Genes and Genomes analysis. The novel findings warrant deeper investigation of the influence of DXM on growth and other pathways in this neglected tropical disease pathogen, particularly in a setting of autoimmune and/or allergic disease, which may require the clinical use of steroid-like hormones during latent or covert strongyloidiasis.

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Suitability of Free-Living Marine Nematodes as Bioindicators: Status and Future Considerations

Frontiers in Marine Science ◽

10.3389/fmars.2021.685327 ◽

2021 ◽

Vol 8 ◽

Author(s):

Aaron Ridall ◽

Jeroen Ingels

Keyword(s):

Heavy Metal ◽

Ecosystem Health ◽

Marine Nematodes ◽

Free Living ◽

Future Directions ◽

The Past ◽

Ocean Pollution ◽

Biological Health ◽

Global Biodiversity ◽

Species Specific

Nematodes are among the most abundant organisms on Earth, and have important roles in terrestrial, freshwater, and marine ecosystems. Free-living marine nematodes have been used successfully as indicators of biological health and ocean pollution for at least the past 40 years, but their use as bioindicators is not ubiquitous. They have been most often used specifically as indicators of heavy metal and hydrocarbon pollution, with far fewer instances of their use as indicators of biological, environmental, or physical perturbations. Although free-living marine nematodes are among the best bioindicators owing to their worldwide distributions, abundances, and genus- and species-specific responses to environmental pollution, there are still some challenges that prevent their use globally. Here, we present a review of characteristics that make free-living marine nematodes excellent bioindicators, recent studies that have used them as bioindicators, and suggestions for future directions in the use of these fauna as indicators in the marine environment. Specifically, we consider the use of marine nematodes for microplastics (an understudied class of pollutants that are a future threat to global biodiversity), the value of current nematode indices as measures of ecosystem health, and the importance of improved and continued international collaboration in the field of marine nematology.

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Detection and quantification of house mouse Eimeria at the species level – challenges and solutions for the assessment of Coccidia in wildlife

10.1101/636662 ◽

2019 ◽

Cited By ~ 3

Author(s):

Víctor Hugo Jarquín-Díaz ◽

Alice Balard ◽

Jenny Jost ◽

Julia Kraft ◽

Mert Naci Dikmen ◽

...

Keyword(s):

House Mouse ◽

Parasite Species ◽

Host Population ◽

Species Level ◽

Free Living ◽

Additional Indication ◽

Tissue Samples ◽

Species Specific ◽

Apicoplast Genome ◽

Detection And Quantification

AbstractDetection and quantification of coccidia in studies of wildlife can be challenging. Therefore, the prevalence of coccidia is often not assessed at the parasite species level in non-livestock animals. Parasite species-specific prevalences are especially important when studying evolutionary questions in wild populations. We tested whether increased host population density increases the prevalence of individual Eimeria species at the farm level, as predicted by epidemiological theory. We studied free-living commensal populations of the house mouse (Mus musculus) in Germany and established a strategy to detect and quantify Eimeria infections. We show that a novel diagnostic primer targeting the apicoplast genome (Ap5) and coprological assessment after flotation provide complementary detection results increasing sensitivity. Genotyping PCRs confirm detection in a subset of samples and cross-validation of different PCR markers does not indicate a bias towards a particular parasite species in genotyping. We were able to detect double infections and to determine the preferred niche of each parasite species along the distal-proximal axis of the intestine. Parasite genotyping from tissue samples provides an additional indication for the absence of species bias in genotyping amplifications. Three Eimeria species were found infecting house mice at different prevalences: Eimeria ferrisi (16.7%; 95% CI 13.2 – 20.7), E. falciformis (4.2%; 95% CI 2.6 – 6.8) and E. vermiformis (1.9%; 95% CI 0.9 – 3.8). We also find that mice in dense populations are more likely to be infected with E. falciformis and E. ferrisi.We provide methods for the assessment of prevalences of coccidia at the species level in rodent systems. We show and discuss how such data can help to test hypotheses in ecology, evolution and epidemiology on a species level.

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In vitro proteolysis of nematode FMRFamide-like peptides (FLPs) by preparations from a free-living nematode (Panagrellus redivivus) and two plant-parasitic nematodes (Heteroderaglycines and Meloidogyne incognita)

Journal of Helminthology ◽

10.1017/s0022149x1100006x ◽

2011 ◽

Vol 86 (1) ◽

pp. 77-84 ◽

Cited By ~ 5

Author(s):

E.P. Masler

Keyword(s):

Cathepsin L ◽

Cysteine Proteases ◽

Developmental Differences ◽

Parasitic Nematodes ◽

Free Living ◽

Additional Species ◽

Substrate Preferences ◽

Panagrellus Redivivus ◽

Species Specific

AbstractProteolytic activities in extracts from three nematodes, the plant parasites Heterodera glycines and Meloidogyneincognita, and the free-living Panagrellus redivivus, were surveyed for substrate preferences using a battery of seven FRET-modified peptide substrates, all derived from members of the large FMRF-amide like peptide (FLP) family in nematodes. Overall protease activity in P. redivivus was four- to fivefold greater than in either of the parasites, a result that might reflect developmental differences. Digestion of the M. incognita FLP KHEFVRFa (substrate Abz-KHEFVRF-Y(3-NO2)a) by M. incognita extract was sevenfold greater than with H. glycines extract and twofold greater than P. redivivus, suggesting species-specific preferences. Additional species differences were revealed upon screening 12 different protease inhibitors. Two substrates were used in the screen, Abz-KHEFVRF-Y(3-NO2)a and Abz-KPSFVRF-Y(3-NO2)a), which was digested equally by all three species. The effects of various inhibitor, substrate and extract source combinations on substrate digestion suggest that M. incognita differs significantly from P. redivivus and H. glycines in its complement of cysteine proteases, particularly cathepsin L-type protease.

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Skin-penetrating nematodes exhibit life-stage-specific interactions with host-associated and environmental bacteria

BMC Biology ◽

10.1186/s12915-021-01153-7 ◽

2021 ◽

Vol 19 (1) ◽

Author(s):

Ivan N. Chavez ◽

Taylor M. Brown ◽

Adrien Assié ◽

Astra S. Bryant ◽

Buck S. Samuel ◽

...

Keyword(s):

Life Cycle ◽

Life Stage ◽

Behavioral Responses ◽

Strongyloides Stercoralis ◽

Amplicon Sequencing ◽

Ecological Niches ◽

Free Living ◽

Egg Hatching ◽

Host Seeking ◽

Environmental Bacteria

Abstract Background Skin-penetrating nematodes of the genus Strongyloides infect over 600 million people, posing a major global health burden. Their life cycle includes both a parasitic and free-living generation. During the parasitic generation, infective third-stage larvae (iL3s) actively engage in host seeking. During the free-living generation, the nematodes develop and reproduce on host feces. At different points during their life cycle, Strongyloides species encounter a wide variety of host-associated and environmental bacteria. However, the microbiome associated with Strongyloides species, and the behavioral and physiological interactions between Strongyloides species and bacteria, remain unclear. Results We first investigated the microbiome of the human parasite Strongyloides stercoralis using 16S-based amplicon sequencing. We found that S. stercoralis free-living adults have an associated microbiome consisting of specific fecal bacteria. We then investigated the behavioral responses of S. stercoralis and the closely related rat parasite Strongyloides ratti to an ecologically diverse panel of bacteria. We found that S. stercoralis and S. ratti showed similar responses to bacteria. The responses of both nematodes to bacteria varied dramatically across life stages: free-living adults were strongly attracted to most of the bacteria tested, while iL3s were attracted specifically to a narrow range of environmental bacteria. The behavioral responses to bacteria were dynamic, consisting of distinct short- and long-term behaviors. Finally, a comparison of the growth and reproduction of S. stercoralis free-living adults on different bacteria revealed that the bacterium Proteus mirabilis inhibits S. stercoralis egg hatching, and thereby greatly decreases parasite viability. Conclusions Skin-penetrating nematodes encounter bacteria from various ecological niches throughout their life cycle. Our results demonstrate that bacteria function as key chemosensory cues for directing parasite movement in a life-stage-specific manner. Some bacterial genera may form essential associations with the nematodes, while others are detrimental and serve as a potential source of novel nematicides.

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