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Trends in Parasitology Jul 2022Zoonotic cestodes of the genus Echinococcus show marked differences in their distribution patterns which have not been satisfactorily explained. Echinococcus... (Review)
Review
Zoonotic cestodes of the genus Echinococcus show marked differences in their distribution patterns which have not been satisfactorily explained. Echinococcus multilocularis is limited to the Holarctic, whereas species in the Echinococcus granulosus sensu lato (s.l.) complex mostly have a worldwide distribution. We proposed and tested a 'bridge effect' hypothesis stating that the low virulence of species in the E. granulosus s.l. complex for their intermediate hosts and a longer lifespan of infected hosts explain the differential distributions, particularly in hot and dry regions. This does not exclude the contribution of other factors such as human-mediated dispersal and intermediate host distribution. In the light of globalization and climate change, understanding what drives the distribution of zoonotic parasites is critical for preventing outbreaks of disease caused by these pathogens.
Topics: Animals; Echinococcosis; Echinococcus granulosus; Echinococcus multilocularis; Genotype; Humans
PubMed: 35508436
DOI: 10.1016/j.pt.2022.04.003 -
Journal of Helminthology Mar 2023Given their sheer cumulative biomass and ubiquitous presence, parasites are increasingly recognized as essential components of most food webs. Beyond their influence as... (Review)
Review
Given their sheer cumulative biomass and ubiquitous presence, parasites are increasingly recognized as essential components of most food webs. Beyond their influence as consumers of host tissue, many parasites also have free-living infectious stages that may be ingested by non-host organisms, with implications for energy and nutrient transfer, as well as for pathogen transmission and infectious disease dynamics. This has been particularly well-documented for the cercaria free-living stage of digenean trematode parasites within the Phylum Platyhelminthes. Here, we aim to synthesize the current state of knowledge regarding cercariae consumption by examining: (a) approaches for studying cercariae consumption; (b) the range of consumers and trematode prey documented thus far; (c) factors influencing the likelihood of cercariae consumption; (d) consequences of cercariae consumption for individual predators (e.g. their viability as a food source); and (e) implications of cercariae consumption for entire communities and ecosystems (e.g. transmission, nutrient cycling and influences on other prey). We detected 121 unique consumer-by-cercaria combinations that spanned 60 species of consumer and 35 trematode species. Meaningful reductions in transmission were seen for 31 of 36 combinations that considered this; however, separate studies with the same cercaria and consumer sometimes showed different results. Along with addressing knowledge gaps and suggesting future research directions, we highlight how the conceptual and empirical approaches discussed here for consumption of cercariae are relevant for the infectious stages of other parasites and pathogens, illustrating the use of cercariae as a model system to help advance our knowledge regarding the general importance of parasite consumption.
Topics: Animals; Parasites; Ecosystem; Trematode Infections; Trematoda; Food Chain; Cercaria
PubMed: 36971341
DOI: 10.1017/S0022149X23000111 -
Veterinary Parasitology, Regional... Feb 2022Gastrointestinal parasite infections in livestock and companion animals in Mongolia have not been investigated sufficiently. This study aimed to determine the prevalence...
Gastrointestinal parasite infections in livestock and companion animals in Mongolia have not been investigated sufficiently. This study aimed to determine the prevalence of cyclophyllid cestodes (Taeniidae and Mesocestoididae) in Mongolian sheepdogs using copro-DNA analysis. Sheepdog fecal samples (n = 1242) were collected from five ecological zones (mountain taiga, forest-steppe, steppe, desert-steppe, and desert) and four geographical regions (Western, Khangai, Central, and Eastern) within 20 of the country's 21 provinces. Among the 1242 samples, 201 (16.2%) tested positive for mitochondrial cytochrome c oxidase subunit 1 (cox1) and ribosomal 12S rRNA encoding genes of cyclophyllid cestodes. Prevalence in the mountain taiga, forest-steppe, steppe, desert-steppe, and desert zones was 29.2%, 15.4%, 15.1%, 20.1%, and 9.1%, respectively. Prevalence in the Western, Khangai, Central, and Eastern regions was 19.9%, 18.6%, 12.1%, and 12.8%, respectively. Taenia hydatigena, Taenia multiceps, and two Mesocestoides species (Mesocestoides sp.1 and Mesocestoides sp.2) were identified. T. hydatigena was found in the samples from all 20 provinces (all five zones and four regions), while T. multiceps was detected in the samples from 19 provinces (all five zones and four regions). Mesocestoides sp.1 infection was detected in the samples from all zones (except desert) and regions; it was detected in 14 provinces. Mesocestoides sp.2 infection was detected in the samples from all zones (except mountain taiga) and regions and found in seven provinces. Cyclophyllidea infection in sheepdogs is highly prevalent across Mongolia, representing a zoonotic risk. Implementation of a surveillance program for sheepdogs and their owners, and the wild animals in all ecological zones should be considered. In addition, control measures, including public awareness campaigns, especially for sheepdog owners, and periodic deworming of sheepdogs are warranted.
Topics: Animals; Cestoda; Cestode Infections; Mesocestoides; Prevalence; Taenia
PubMed: 35115119
DOI: 10.1016/j.vprsr.2021.100680 -
Development (Cambridge, England) Jul 2021Acoels are marine worms that belong to the phylum Xenacoelomorpha, a deep-diverging bilaterian lineage. This makes acoels an attractive system for studying the evolution...
Acoels are marine worms that belong to the phylum Xenacoelomorpha, a deep-diverging bilaterian lineage. This makes acoels an attractive system for studying the evolution of major bilaterian traits. Thus far, acoel development has not been described in detail at the morphological and transcriptomic levels in a species in which functional genetic studies are possible. We present a set of developmental landmarks for embryogenesis in the highly regenerative acoel Hofstenia miamia. We generated a developmental staging atlas from zygote to hatched worm based on gross morphology, with accompanying bulk transcriptome data. Hofstenia embryos undergo a stereotyped cleavage program known as duet cleavage, which results in two large vegetal pole 'macromeres' and numerous small animal pole 'micromeres'. These macromeres become internalized as micromere progeny proliferate and move vegetally. We also noted a second, previously undescribed, cell-internalization event at the animal pole, following which we detected major body axes and tissues corresponding to all three germ layers. Our work on Hofstenia embryos provides a resource for mechanistic investigations of acoel development, which will yield insights into the evolution of bilaterian development and regeneration.
Topics: Animals; Embryonic Development; Germ Layers; Platyhelminths; Regeneration; Transcriptome
PubMed: 34196362
DOI: 10.1242/dev.188656 -
Neural Development Jun 2024Acoel flatworms have played a relevant role in classical (and current) discussions on the evolutionary origin of bilaterian animals. This is mostly derived from the... (Review)
Review
Acoel flatworms have played a relevant role in classical (and current) discussions on the evolutionary origin of bilaterian animals. This is mostly derived from the apparent simplicity of their body architectures. This tenet has been challenged over the last couple of decades, mostly because detailed studies of their morphology and the introduction of multiple genomic technologies have unveiled a complexity of cell types, tissular arrangements and patterning mechanisms that were hidden below this 'superficial' simplicity. One tissue that has received a particular attention has been the nervous system (NS). The combination of ultrastructural and single cell methodologies has revealed unique cellular diversity and developmental trajectories for most of their neurons and associated sensory systems. Moreover, the great diversity in NS architectures shown by different acoels offers us with a unique group of animals where to study key aspects of neurogenesis and diversification od neural systems over evolutionary time.In this review we revisit some recent developments in the characterization of the acoel nervous system structure and the regulatory mechanisms that contribute to their embryological development. We end up by suggesting some promising avenues to better understand how this tissue is organized in its finest cellular details and how to achieve a deeper knowledge of the functional roles that genes and gene networks play in its construction.
Topics: Animals; Nervous System; Neurogenesis; Platyhelminths; Biological Evolution; Neurons
PubMed: 38907301
DOI: 10.1186/s13064-024-00187-1 -
Current Topics in Developmental Biology 2022Platyhelminthes can perhaps rightly be described as a phylum of the good, the bad, and the ugly: remarkable free-living worms that colonize land, river, and sea, which...
Platyhelminthes can perhaps rightly be described as a phylum of the good, the bad, and the ugly: remarkable free-living worms that colonize land, river, and sea, which are often rife with color and can display extraordinary regenerative ability; parasitic worms like schistosomes that cause devastating disease and suffering; and monstrous tapeworms that are the stuff of nightmares. In this chapter, we will explore how our research expanded beyond free-living planarians to their gruesome parasitic cousins. We start with Schistosoma mansoni, which is not a new model; however, approaching these parasites from a developmental perspective required a reinvention that may hold generalizable lessons to basic biologists interested in pivoting to disease models. We then turn to our (re)establishment of the rat tapeworm Hymenolepis diminuta, a once-favorite model that had been largely forgotten by the molecular biology revolution. Here we tell our stories in three, first-person narratives in order to convey personal views of our experiences. Welcome to the dark side.
Topics: Animals; Humans; Parasites; Planarians; Rats; bcl-Associated Death Protein
PubMed: 35337455
DOI: 10.1016/bs.ctdb.2021.12.015 -
Trends in Parasitology May 2022Aquatic snails, the intermediate hosts of schistosomes, harbor a diverse unexplored microbiome. We speculate that this may play a critical role in host-parasite...
Aquatic snails, the intermediate hosts of schistosomes, harbor a diverse unexplored microbiome. We speculate that this may play a critical role in host-parasite interactions. We summarize our current knowledge of snail microbiomes and highlight future research priorities.
Topics: Animals; Biomphalaria; Host-Parasite Interactions; Microbiota; Schistosoma; Schistosoma mansoni
PubMed: 35190282
DOI: 10.1016/j.pt.2022.01.012 -
Frontiers in Cellular and Infection... 2021Platyhelminthes comprise one of the major phyla of invertebrate animals, inhabiting a wide range of ecosystems, and one of the most successful in adapting to parasitic...
Platyhelminthes comprise one of the major phyla of invertebrate animals, inhabiting a wide range of ecosystems, and one of the most successful in adapting to parasitic life. Small non-coding RNAs have been implicated in regulating complex developmental transitions in model parasitic species. Notably, parasitic flatworms have lost Piwi RNA pathways but gained a novel Argonaute gene. Herein, we analyzed, contrasted and compared the conservation of small RNA pathways among several free-living species (a paraphyletic group traditionally known as 'turbellarians') and parasitic species (organized in the monophyletic clade Neodermata) to disentangle possible adaptations during the transition to parasitism. Our findings showed that complete miRNA and RNAi pathways are present in all analyzed free-living flatworms. Remarkably, whilst all 'turbellarians' have Piwi proteins, these were lost in parasitic Neodermantans. Moreover, two clusters of Piwi class Argonaute genes are present in all 'turbellarians'. Interestingly, we identified a divergent Piwi class Argonaute in free living flatworms exclusively, which we named 'Fliwi'. In addition, other key proteins of the Piwi pathways were conserved in 'turbellarians', while none of them were detected in Neodermatans. Besides Piwi and the canonical Argonaute proteins, a flatworm-specific class of Argonautes (FL-Ago) was identified in the analyzed species confirming its ancestrallity to all Platyhelminthes. Remarkably, this clade was expanded in parasitic Neodermatans, but not in free-living species. These phyla-specific Argonautes showed lower sequence conservation compared to other Argonaute proteins, suggesting that they might have been subjected to high evolutionary rates. However, key residues involved in the interaction with the small RNA and mRNA cleavage in the canonical Argonautes were more conserved in the FL-Agos than in the Piwi Argonautes. Whether this is related to specialized functions and adaptations to parasitism in Neodermatans remains unclear. In conclusion, differences detected in gene conservation, sequence and structure of the Argonaute family suggest tentative biological and evolutionary diversifications that are unique to Platyhelminthes. The remarkable divergencies in the small RNA pathways between free-living and parasitic flatworms indicate that they may have been involved in the adaptation to parasitism of Neodermatans.
Topics: Animals; Argonaute Proteins; Ecosystem; Phylogeny; Platyhelminths; RNA Interference; RNA, Small Interfering
PubMed: 34123869
DOI: 10.3389/fcimb.2021.653695 -
Zootaxa Mar 2021The taxon Koinocystididae is the third most species-rich family within Eukalyptorhynchia. However, its diversity and phylogeny have been largely neglected in former...
The taxon Koinocystididae is the third most species-rich family within Eukalyptorhynchia. However, its diversity and phylogeny have been largely neglected in former studies. We introduce three new genera and twelve new species of Koinocystididae including Simplexcystis asymmetrica gen. n. sp. n., Galapagetula cubensis sp. n., eight species of Reinhardorhynchus gen. n. and two species of Itaipusa. This raises the total number of species within Koinocystididae from 51 to 63. We also report on new distribution records for six known species: I. divae (Cuba, Panama and New Caledonia), I. karlingi (Sardinia and Lanzarote), Reinhardorhynchus riegeri comb. n. (Cuba), R. ruffinjonesi comb. n. (Cuba and Panama), Utelga heinckei (Cuba and Lanzarote), and U. pseudoheinckei (Sardinia). Simplexcystis asymmetrica gen. n. sp. n. is characterised by a male duct running eccentrically through the copulatory bulb, lack of any hard structures in the male system, lack of a bursa, and the fact that the epithelia of the female, the male, and part of the common atrium are covered by a brush border. Galapagetula cubensis sp. n. has a caudal gonopore, a divisa-type copulatory bulb with an unarmed penis papilla, and a female duct without a sphincter. The new species of Itaipusa and Reinhardorhynchus gen. n. differ from their congeners in the detailed structure of the copulatory bulb and especially the hard structures associated with it. In a molecular phylogenetic analysis based on all available 18S and 28S rDNA sequences of koinocystidids, we found support for the monophyly of the family and the genus Utelga Marcus, 1949. The genus Itaipusa is not monophyletic in that I. sinensis forms a clade with Rhinolasius dillonicus, while other species of Itaipusa that have a copulatory bulb armed with hooks form a clade together with Sekerana stolzi. As the type species of Itaipusa (I. divae) is in neither of these clades, we erected a new genus for I. sinensis (Koinogladius gen. n.) and one for species of Itaipusa having a hook-bearing copulatory bulb (Reinhardorhynchus gen. n.), respectively. Whether the remaining species of Itaipusa form a monophylum remains uncertain.
Topics: Animals; Female; Male; Phylogeny; Platyhelminths
PubMed: 33757005
DOI: 10.11646/zootaxa.4948.4.1 -
PeerJ 2022New records of alien land planarians are regularly reported worldwide, and some correspond to undescribed species of unknown geographic origin. The description of new...
BACKGROUND
New records of alien land planarians are regularly reported worldwide, and some correspond to undescribed species of unknown geographic origin. The description of new species of land planarians (Geoplanidae) should classically be based on both external morphology and histology of anatomical structures, especially the copulatory organs, ideally with the addition of molecular data.
METHODS
Here, we describe the morphology and reproductive anatomy of a species previously reported as "black", and the morphology of a species previously reported as "blue". Based on next generation sequencing, we obtained the complete mitogenome of five species of Bipaliinae, including these two species.
RESULTS
The new species n. sp. (syn: "black" of Justine et al., 2018) is formally described on the basis of morphology, histology and mitogenome, and is assigned to on the basis of its reproductive anatomy. The type-locality is Casier, Italy, and other localities are in the Department of Pyrénées-Atlantiques, France; some published or unpublished records suggest that this species might also be present in Russia, China, and Japan. The mitogenomic polymorphism of two geographically distinct specimens (Italy France) is described; the gene displayed 2.25% difference. The new species n. sp. (syn: "blue" of Justine et al., 2018) is formally described on the basis of external morphology and complete mitogenome and is assigned to on the basis of an absence of information on its reproductive anatomy. The type- and only known locality is the island of Mayotte in the Mozambique Channel off Africa. Phylogenies of bipaliine geoplanids were constructed on the basis of SSU, LSU, mitochondrial proteins and concatenated sequences of , SSU and LSU. In all four phylogenies, was the sister-group to all the other bipaliines. With the exception of which could not be circularised, the complete mitogenomes of , , , and were colinear. The 16S gene in all bipaliine species was problematic because usual tools were unable to locate its exact position.
CONCLUSION
Next generation sequencing, which can provide complete mitochondrial genomes as well as traditionally used genes such as SSU, LSU and , is a powerful tool for delineating and describing species of Bipaliinae when the reproductive structure cannot be studied, which is sometimes the case of asexually reproducing invasive species. The unexpected position of the new species as sister-group to all other Bipaliinae in all phylogenetic analyses suggests that the species could belong to a new genus, yet to be described.
Topics: Animals; Genome, Mitochondrial; Phylogeny; Comoros; Planarians; Italy; France
PubMed: 35178290
DOI: 10.7717/peerj.12725