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Lancet (London, England) Sep 2020
Topics: Animals; Cestoda; Diphyllobothriasis; Diphyllobothrium; Humans; Intestines
PubMed: 32919507
DOI: 10.1016/S0140-6736(20)31192-2 -
Parasitology Research Apr 2022The first cestode genomes were obtained by an international consortium led by the Wellcome Sanger Institute that included representative institutions from countries... (Review)
Review
The first cestode genomes were obtained by an international consortium led by the Wellcome Sanger Institute that included representative institutions from countries where the sequenced parasites have been studied for decades, in part because they are etiological agents of endemic diseases (Argentina, Uruguay, Mexico, Canada, UK, Germany, Switzerland, Ireland, USA, Japan, and China). After this, several complete genomes were obtained reaching 16 species to date. Cestode genomes have smaller relative size compared to other animals including free-living flatworms. Moreover, the features genome size and repeat content seem to differ in the two analyzed orders. Cyclophyllidean species have smaller genomes and with fewer repetitive content than Diphyllobothriidean species. On average, cestode genomes have 13,753 genes with 6 exons per gene and 41% GC content. More than 5,000 shared cestode proteins were accurately annotated by the integration of gene predictions and transcriptome evidence being more than 40% of these proteins of unknown function. Several gene losses and reduction of gene families were found and could be related to the extreme parasitic lifestyle of these species. The application of cutting-edge sequencing technology allowed the characterization of the terminal sequences of chromosomes that possess unique characteristics. Here, we review the current status of knowledge of complete cestode genomes and place it within a comparative genomics perspective. Multidisciplinary work together with the implementation of new technologies will provide valuable information that can certainly improve our chances to finally eradicate or at least control diseases caused by cestodes.
Topics: Animals; Cestoda; Cestode Infections; Genomics; Platyhelminths; Sequence Analysis, DNA
PubMed: 34665308
DOI: 10.1007/s00436-021-07346-x -
Marine Drugs Jan 2021Marine invertebrates are promising sources of novel bioactive secondary metabolites, and organisms like sponges, ascidians and nudibranchs are characterised by... (Review)
Review
Marine invertebrates are promising sources of novel bioactive secondary metabolites, and organisms like sponges, ascidians and nudibranchs are characterised by possessing potent defensive chemicals. Animals that possess chemical defences often advertise this fact with aposematic colouration that potential predators learn to avoid. One seemingly defenceless group that can present bright colouration patterns are flatworms of the order Polycladida. Although members of this group have typically been overlooked due to their solitary and benthic nature, recent studies have isolated the neurotoxin tetrodotoxin from these mesopredators. This review considers the potential of polyclads as potential sources of natural products and reviews what is known of the activity of the molecules found in these animals. Considering the ecology and diversity of polyclads, only a small number of species from both suborders of Polycladida, Acotylea and Cotylea have been investigated for natural products. As such, confirming assumptions as to which species are in any sense toxic or if the compounds they use are biosynthesised, accumulated from food or the product of symbiotic bacteria is difficult. However, further research into the group is suggested as these animals often display aposematic colouration and are known to prey on invertebrates rich in bioactive secondary metabolites.
Topics: Animals; Biological Products; Platyhelminths; Protein Structure, Secondary; Protein Structure, Tertiary; Secondary Metabolism
PubMed: 33494164
DOI: 10.3390/md19020047 -
Molecular and Biochemical Parasitology Oct 2019Nuclear receptors (NRs) belong to a large protein superfamily which includes intracellular receptors for secreted hydrophobic signal molecules, such as steroid hormones... (Review)
Review
Nuclear receptors (NRs) belong to a large protein superfamily which includes intracellular receptors for secreted hydrophobic signal molecules, such as steroid hormones and thyroid hormones. They regulate development and reproduction in metazoans by binding to the promoter region of their target gene to activate or repress mRNA synthesis. Isolation and characterization of NRs in the parasitic trematode Schistosoma mansoni identified two homologues of mammalian thyroid receptor (TR). This was the first known protostome exhibiting TR homologues. Three novel NRs each possess a novel set of two DNA binding domains (DBD) in tandem with a ligand binding domain (LBD) (2DBD-NRs) isolated in Schistosoma mansoni revealed a novel NR modular structure: A/B-DBD-DBD-hinge-LBD. Full length cDNA of several NRs have been isolated and studied in the parasitic trematodes S. mansoni, S. japonicum and in the cestode Echinococcus multilocularis. The genome of the blood flukes S. mansoni, S. japonicum and S. haematobium, the liver fluke Clonorchis sinensis and the cestode Echinococcus multilocularis have been sequenced. Study of the NR complement in parasitic Platyhelminths will help us to understand the role of NRs in regulation of their development and understand the evolution of NR in animals.
Topics: Animals; Clonorchis sinensis; Echinococcus multilocularis; Evolution, Molecular; Helminth Proteins; Phylogeny; Platyhelminths; Receptors, Cytoplasmic and Nuclear; Schistosoma; Schistosoma mansoni
PubMed: 31470045
DOI: 10.1016/j.molbiopara.2019.111218 -
Nucleic Acids Research Mar 2022Parasitic helminths infecting humans are highly prevalent infecting ∼2 billion people worldwide, causing inflammatory responses, malnutrition and anemia that are the...
Parasitic helminths infecting humans are highly prevalent infecting ∼2 billion people worldwide, causing inflammatory responses, malnutrition and anemia that are the primary cause of morbidity. In addition, helminth infections of cattle have a significant economic impact on livestock production, milk yield and fertility. The etiological agents of helminth infections are mainly Nematodes (roundworms) and Platyhelminths (flatworms). G-quadruplexes (G4) are unusual nucleic acid structures formed by G-rich sequences that can be recognized by specific G4 ligands. Here we used the G4Hunter Web Tool to identify and compare potential G4 sequences (PQS) in the nuclear and mitochondrial genomes of various helminths to identify G4 ligand targets. PQS are nonrandomly distributed in these genomes and often located in the proximity of genes. Unexpectedly, a Nematode, Ascaris lumbricoides, was found to be highly enriched in stable PQS. This species can tolerate high-stability G4 structures, which are not counter selected at all, in stark contrast to most other species. We experimentally confirmed G4 formation for sequences found in four different parasitic helminths. Small molecules able to selectively recognize G4 were found to bind to Schistosoma mansoni G4 motifs. Two of these ligands demonstrated potent activity both against larval and adult stages of this parasite.
Topics: Animals; Cattle; G-Quadruplexes; Genome; Helminths; Humans; Ligands; Nematoda; Parasites; Platyhelminths
PubMed: 35234933
DOI: 10.1093/nar/gkac129 -
Parasitology Sep 2022Foodborne trematodes (FBT) of public health significance include liver flukes ( and ), lung flukes ( and several other spp.) and intestinal flukes, which include... (Review)
Review
Foodborne trematodes (FBT) of public health significance include liver flukes ( and ), lung flukes ( and several other spp.) and intestinal flukes, which include heterophyids ( and ), echinostomes ( and ) and miscellaneous species, including and . These trematode infections are distributed worldwide but occur most commonly in Asia. The global burden of FBT diseases has been estimated at about 80 million, however, this seems to be a considerable underestimate. Their life cycle involves a molluscan first intermediate host, and a second intermediate host, including freshwater fish, crustaceans, aquatic vegetables and freshwater or brackish water gastropods and bivalves. The mode of human infection is the consumption of the second intermediate host under raw or improperly cooked conditions. The major pathogenesis of and spp. infection includes inflammation of the bile duct which leads to cholangitis and cholecystitis, and in a substantial number of patients, serious complications, such as liver cirrhosis and cholangiocarcinoma, may develop. In lung fluke infections, cough, bloody sputum and bronchiectasis are the most common clinical manifestations. However, lung flukes often migrate to extrapulmonary sites, including the brain, spinal cord, skin, subcutaneous tissues and abdominal organs. Intestinal flukes can induce inflammation in the intestinal mucosa, and they may at times undergo extraintestinal migration, in particular, in immunocompromised patients. In order to control FBT infections, eating foods after proper cooking is strongly recommended.
Topics: Animals; Echinostoma; Fascioliasis; Heterophyidae; Humans; Inflammation; Trematoda; Trematode Infections
PubMed: 35591777
DOI: 10.1017/S0031182022000725 -
Veterinary Parasitology, Regional... Apr 2021Digeneans are an important class of trematodes which infect variety of animals ranging from vertebrates (mainly final hosts) to invertebrates (mainly as intermediate... (Review)
Review
Digeneans are an important class of trematodes which infect variety of animals ranging from vertebrates (mainly final hosts) to invertebrates (mainly as intermediate hosts). Additionally, some of these parasites are zoonotic and one health importance. Diversity of digeneans in Iran and reports of several zoonotic cases show the importance of these parasites in this country. This is the checklist of digenean parasites reported from Iran representing a total of 118 species, from 105 genera, 43 families, 21 subfamilies, and 3 orders that are reported from 139 species of different hosts including humans. Some of the most important final number of families, genera, and species reported in Iran fauna include: Fasciolidae, Genus: Fasciola, Fasciola gigantica, Fasciola hepatica, Family: Dicrocoeliidae, Genus: Dicrocoelium, Dicrocoelium dendriticum, Family: Diplostomidae, Genus: Diplostomum, Diplostomum spathaceum, Family: Heterophyidae, Genus: Haplorchis, Haplorchis taichui, Family: Notocotylidae, Genus: Notocotylu, Notocotylus aegyptiacus, Family: Bucephalidae, Genus: Rhipidocotyle, Rhipidocotyle illense.
Topics: Animals; Checklist; Dicrocoelium; Fasciola; Iran; Trematoda
PubMed: 34024387
DOI: 10.1016/j.vprsr.2021.100571 -
Journal of Microbiological Methods Aug 2021The superfamily Opisthorchioidea encompasses the families Cryptogonimidae, Opisthorchiidae and Heterophyidae. These parasites depend on the aquatic environment and... (Review)
Review
The superfamily Opisthorchioidea encompasses the families Cryptogonimidae, Opisthorchiidae and Heterophyidae. These parasites depend on the aquatic environment and include marine and freshwater species. Some species, such as Clonorchis sinensis and Opisthorchis viverrini, have a high impact on public health with millions of infected people worldwide and have thus been the object of many studies and tool developments. However, for many species, tools for identification and detection are scarce. Although morphological descriptions have been used and are still important, they are often not efficient on the immature stages of these parasites. Thus, during the past few decades, molecular approaches for parasite identification have become commonplace. These approaches are efficient, quick and reliable. Nonetheless, for some parasites of the superfamily Opisthorchioidea, reference genomic data are limited. This study reviews available genetic data and molecular tools for the identification and/or the detection of this superfamily. Molecular data on this superfamily are mostly based on mitochondrial and ribosomal gene sequence analyses, especially on the cytochrome c oxidase subunit 1 gene and internal transcribed spacer regions respectively.
Topics: Animals; DNA Primers; DNA, Helminth; DNA, Mitochondrial; DNA, Ribosomal; DNA, Ribosomal Spacer; Electron Transport Complex IV; Genes, Helminth; Heterophyidae; Molecular Diagnostic Techniques; Nucleic Acid Amplification Techniques; Opisthorchidae; Parasitology; Phylogeny; Polymerase Chain Reaction; Polymorphism, Restriction Fragment Length; Random Amplified Polymorphic DNA Technique; Trematoda
PubMed: 34082051
DOI: 10.1016/j.mimet.2021.106258 -
Frontiers in Cellular and Infection... 2021An organism responds to the invading pathogens such as bacteria, viruses, protozoans, and fungi by engaging innate and adaptive immune system, which functions by... (Review)
Review
An organism responds to the invading pathogens such as bacteria, viruses, protozoans, and fungi by engaging innate and adaptive immune system, which functions by activating various signal transduction pathways. As invertebrate organisms (such as sponges, worms, cnidarians, molluscs, crustaceans, insects, and echinoderms) are devoid of an adaptive immune system, and their defense mechanisms solely rely on innate immune system components. Investigating the immune response in such organisms helps to elucidate the immune mechanisms that vertebrates have inherited or evolved from invertebrates. Planarians are non-parasitic invertebrates from the phylum Platyhelminthes and are being investigated for several decades for understanding the whole-body regeneration process. However, recent findings have emerged planarians as a useful model for studying innate immunity as they are resistant to a broad spectrum of bacteria. This review intends to highlight the research findings on various antimicrobial resistance genes, signaling pathways involved in innate immune recognition, immune-related memory and immune cells in planarian flatworms.
Topics: Animals; Immune System; Immunity, Innate; Insecta; Planarians; Signal Transduction
PubMed: 33732660
DOI: 10.3389/fcimb.2021.619081 -
Sleep May 2022Sleep is a prominent behavioral and biochemical state observed in all animals studied, including platyhelminth flatworms. Investigations into the biochemical mechanisms...
STUDY OBJECTIVES
Sleep is a prominent behavioral and biochemical state observed in all animals studied, including platyhelminth flatworms. Investigations into the biochemical mechanisms associated with sleep-and wakefulness-are important for understanding how these states are regulated and how that regulation changed with the evolution of new types of animals. Unfortunately, beyond a handful of vertebrates, such studies on invertebrates are rare.
METHODS
We investigated the effect of seven neurotransmitters, and one pharmacological compound, that modulate either sleep or wakefulness in mammals, on flatworms (Girardia tigrina). Flatworms were exposed via ingestion and diffusion to four neurotransmitters that promote wakefulness in vertebrates (acetylcholine, dopamine, glutamate, histamine), and three that induce sleep (adenosine, GABA, serotonin) along with the H1 histamine receptor antagonist pyrilamine. Compounds were administered over concentrations spanning three to five orders of magnitude. Flatworms were then transferred to fresh water and video recorded for analysis.
RESULTS
Dopamine and histamine decreased the time spent inactive and increased distance traveled, consistent with their wake-promoting effect in vertebrates and fruit flies; pyrilamine increased restfulness and GABA showed a nonsignificant trend towards promoting restfulness in a dose-dependent manner, in agreement with their sleep-inducing effect in vertebrates, fruit flies, and Hydra. Similar to Hydra, acetylcholine, glutamate, and serotonin, but also adenosine, had no apparent effect on flatworm behavior.
CONCLUSIONS
These data demonstrate the potential of neurotransmitters to regulate sleep and wakefulness in flatworms and highlight the conserved action of some neurotransmitters across species.
Topics: Acetylcholine; Adenosine; Animals; Dopamine; Glutamic Acid; Histamine; Mammals; Neurotransmitter Agents; Platyhelminths; Pyrilamine; Serotonin; Sleep; Wakefulness; gamma-Aminobutyric Acid
PubMed: 35554581
DOI: 10.1093/sleep/zsac053