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Ian D. Whittington - One of the best experts on this subject based on the ideXlab platform.
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Closing the mitochondrial circle on paraphyly of the Monogenea (Platyhelminthes) infers evolution in the diet of parasitic flatworms.
International journal for parasitology, 2010Co-Authors: Elizabeth M. Perkins, Steve Donnellan, Terry Bertozzi, Ian D. WhittingtonAbstract:Relationships between the three classes of Neodermata (parasitic Platyhelminthes) are much debated and restrict our understanding of the evolution of parasitism and contingent adaptations. The historic view of a sister relationship between Cestoda and Monogenea (Cercomeromorphae; larvae bearing posterior hooks) has been dismissed and the weight of evidence against Monogenean monophyly has mounted. We present the nucleotide sequence of the complete mitochondrial (mt) genome of Benedenia seriolae (Monogenea: Monopisthocotylea: Capsalidae), the first complete non-gyrodactylid monopisthocotylean mt genome to be reported. We also include nucleotide sequence data for some mt protein coding genes for a second capsalid, Neobenedenia sp. Analyses of the new mt genomes with all available platyhelminth mt genomes provide new phylogenetic hypotheses, which strongly influence perspectives on the evolution of diet in the Neodermata. Our analyses do not support Monogenean monophyly but confirm that the Digenea and Cestoda are each monophyletic and sister groups. Epithelial feeding monopisthocotyleans on fish hosts are basal in the Neodermata and represent the first shift to parasitism from free-living ancestors. The next evolutionary step in parasitism was a dietary change from epithelium to blood. The common ancestor of Digenea + Cestoda was Monogenean-like and most likely sanguinivorous. From this ancestral condition, adult digeneans and cestodes independently evolved dietary specialisations to suit their diverse microhabitats in their final vertebrate hosts. These improved perspectives on relationships fundamentally enhance our understanding of the evolution of parasitism in the Neodermata and in particular, the evolution of diet.
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Decacotyle cairae n. sp. (Monogenea: Monocotylidae) from the gills of Pastinachus sp. (Elasmobranchii: Dasyatidae) from the South China Sea off Sarawak, Borneo, Malaysia
Systematic Parasitology, 2005Co-Authors: Leslie A. Chisholm, Ian D. WhittingtonAbstract:Decacotyle cairae n. sp. (Monogenea: Monocotylidae) is described from the gills of an unidentified species of Pastinachus collected in the South China Sea off Sematan and Mukah, Sarawak, Borneo, Malaysia. D. cairae can be distinguished from the other six members of the genus by the presence of two simple unsclerotised accessory structures on the dorsal surface of the haptor in combination with a long, narrow, looping male copulatory organ. The host specimens of Pastinachus collected in Borneo also appear to be a new species and the Monogenean data support this conclusion. A key to species of Decacotyle is given and their host-specificity is discussed.
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Empruthotrema stenophallus n. sp. (Monogenea: Monocotylidae) from the nasal tissue of Dasyatis kuhlii (Dasyatidae) from Sabah, Borneo, Malaysia.
The Journal of parasitology, 2005Co-Authors: Leslie A. Chisholm, Ian D. WhittingtonAbstract:Empruthotrema stenophallus n. sp. (Monogenea: Monocotylidae) is described from specimens from the nasal tissue of the blue-spotted maskray Dasyatis kuhlii (Muller and Henle, 1841) collected in shallow waters off Pulau Banggi and Pulau Mabul, Sabah, Borneo, Malaysia. This is the first Monogenean species to be described from an elasmobranch collected from Sabah. E. stenophallus can be distinguished from the other 6 members of the genus by the morphology of the sclerotized male copulatory organ, which is narrow, short, and distally tapered. E. dasyatidis Whittington and Kearn, 1992, previously documented from the nasal tissue of several of elasmobranch species from Australia, is recorded from 8 host species distributed around Malaysian Borneo. These represent new host and locality records for this monocotylid. The difficulties in identifying species of Empruthotrema and the apparent lack of host specificity by some members of the genus are discussed.
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Egg hatching in 3 species of monocotylid Monogenean parasites from the shovelnose ray Rhinobatos typus at Heron Island, Australia.
Parasitology, 2000Co-Authors: Leslie A. Chisholm, Ian D. WhittingtonAbstract:Eggs of Neoheterocotyle rhinobatidis, Troglocephalus rhinobatidis and Merizocotyle icopae (Monogenea: Monocotylidae) from the shovelnose ray Rhinobatos typus (Rhinobatidae) have a distinct hatching pattern linked to light periodicity. Larvae of these 3 Monogenean species emerge only during daylight when exposed to natural illumination or when incubated in alternating 12 h periods of light and dark (light on 06.00 h, light off 18.00 h). N. rhinobatidis larvae emerge with a distinct peak during the first 2 h of light; this peak is not as pronounced in T. rhinobatidis or M. icopae. Eggs of N. rhinobatidis incubated in a reverse light/dark cycle (light on 18.00 h, light off 06.00 h) hatched only during periods of illumination, again with a peak during the first 2 h of light. Evidence suggests that the hatching patterns observed in all 3 species represent true circadian rhythms because eggs incubated in 24 h light or 24 h dark conditions continued to hatch with a rhythm. Shadows, disturbance and host tissue did not promote hatching in N. rhinobatidis or T. rhinobatidis but there were indications that host tissue may promote hatching in M. icopae. The hatching patterns observed are discussed with respect to their adaptive responses to host behaviour and predation pressure.
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host specificity of Monogenean platyhelminth parasites a role for anterior adhesive areas
International Journal for Parasitology, 2000Co-Authors: Ian D. Whittington, Bronwen W Cribb, Tamarind E Hamwood, Judy HallidayAbstract:Monogeneans (flatworms) are among the most host-specific of parasites in general and may be the most host-specific of all fish parasites. Specificity, in terms of a restricted spatial distribution within an environment, is not unique to parasites and is displayed by some fungi, insects, birds, symbionts and pelagic larvae of free-living marine invertebrates. The nature of cues, how "habitats" are recognised and how interactions between partners are mediated and maintained is of interest across these diverse "associations". We review some experiments that demonstrate important factors that contribute to host-specificity at the level of infective stages (larvae of oviparous Monogeneans; juveniles of viviparous gyrodactylids) and adult parasites. Recent research on immune responses by fish to Monogenean infections is considered. We emphasise the critical importance of host epidermis to the Monogenea. Monogeneans live on host epidermis, they live in its products (e.g. mucus), monopisthocotyleans feed on it, some of its products are "attractants" and it may be an inhospitable surface because of its immunological activity. We focus attention on fish but reference is made to amphibian hosts. We develop the concept for a potential role in host-specificity by the anterior adhesive areas, either the specialised tegument and/or anterior secretions produced by Monogeneans for temporary but firm attachment during locomotion on host epithelial surfaces. Initial contact between the anterior adhesive areas of infective stages and host epidermis may serve two important purposes. (1) Appropriate sense organs or receptors on the parasite interact with a specific chemical or chemicals or with surface structures on host epidermis. (2) A specific but instant recognition or reaction occurs between component(s) of host mucus and the adhesive(s) secreted by Monogeneans. The chemical composition of fish skin is known to be species-specific and our preliminary analysis of the chemistry of some Monogenean adhesives indicates they are novel proteins that display some differences between parasite families and species.
Gui T. Wang - One of the best experts on this subject based on the ideXlab platform.
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mitochondrial genomes of two diplectanids platyhelminthes Monogenea expose paraphyly of the order dactylogyridea and extensive trna gene rearrangements
Parasites & Vectors, 2018Co-Authors: Dong Zhang, Hong Zou, Jin Zhang, Rong Chen, Ivan Jakovlic, Gui T. WangAbstract:Recent mitochondrial phylogenomics studies have reported a sister-group relationship of the orders Capsalidea and Dactylogyridea, which is inconsistent with previous morphology- and molecular-based phylogenies. As Dactylogyridea mitochondrial genomes (mitogenomes) are currently represented by only one family, to improve the phylogenetic resolution, we sequenced and characterized two dactylogyridean parasites, Lamellodiscus spari and Lepidotrema longipenis, belonging to a non-represented family Diplectanidae. The L. longipenis mitogenome (15,433 bp) contains the standard 36 flatworm mitochondrial genes (atp8 is absent), whereas we failed to detect trnS1, trnC and trnG in L. spari (14,614 bp). Both mitogenomes exhibit unique gene orders (among the Monogenea), with a number of tRNA rearrangements. Both long non-coding regions contain a number of different (partially overlapping) repeat sequences. Intriguingly, these include putative tRNA pseudogenes in a tandem array (17 trnV pseudogenes in L. longipenis, 13 trnY pseudogenes in L. spari). Combined nucleotide diversity, non-synonymous/synonymous substitutions ratio and average sequence identity analyses consistently showed that nad2, nad5 and nad4 were the most variable PCGs, whereas cox1, cox2 and cytb were the most conserved. Phylogenomic analysis showed that the newly sequenced species of the family Diplectanidae formed a sister-group with the Dactylogyridae + Capsalidae clade. Thus Dactylogyridea (represented by the Diplectanidae and Dactylogyridae) was rendered paraphyletic (with high statistical support) by the nested Capsalidea (represented by the Capsalidae) clade. Our results show that nad2, nad5 and nad4 (fast-evolving) would be better candidates than cox1 (slow-evolving) for species identification and population genetics studies in the Diplectanidae. The unique gene order pattern further suggests discontinuous evolution of mitogenomic gene order arrangement in the Class Monogenea. This first report of paraphyly of the Dactylogyridea highlights the need to generate more molecular data for Monogenean parasites, in order to be able to clarify their relationships using large datasets, as single-gene markers appear to provide a phylogenetic resolution which is too low for the task.
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three new diplozoidae mitogenomes expose unusual compositional biases within the Monogenea class implications for phylogenetic studies
BMC Evolutionary Biology, 2018Co-Authors: Dong Zhang, Hong Zou, Jin Zhang, Rong Chen, Ivan Jakovlic, Gui T. WangAbstract:As the topologies produced by previous molecular and morphological studies were contradictory and unstable (polytomy), evolutionary relationships within the Diplozoidae family and the Monogenea class (controversial relationships among the Discocotylinea, Microcotylinea and Gastrocotylinea suborders) remain unresolved. Complete mitogenomes carry a relatively large amount of information, sufficient to provide a much higher phylogenetic resolution than traditionally used morphological traits and/or single molecular markers. However, their implementation is hampered by the scarcity of available Monogenean mitogenomes. Therefore, we sequenced and characterized mitogenomes belonging to three Diplozoidae family species, and conducted comparative genomic and phylogenomic analyses for the entire Monogenea class. Taxonomic identification was inconclusive, so two of the species were identified merely to the genus level. The complete mitogenomes of Sindiplozoon sp. and Eudiplozoon sp. are 14,334 bp and 15,239 bp in size, respectively. Paradiplozoon opsariichthydis (15,385 bp) is incomplete: an approximately 2000 bp-long gap within a non-coding region could not be sequenced. Each genome contains the standard 36 genes (atp8 is missing). G + T content and the degree of GC- and AT-skews of these three mitogenome (and their individual elements) were higher than in other Monogeneans. nad2, atp6 and nad6 were the most variable PCGs, whereas cox1, nad1 and cytb were the most conserved. Mitochondrial phylogenomics analysis, conducted using concatenated amino acid sequences of all PCGs, indicates that evolutionary relationships of the three genera are: (Eudiplozoon, (Paradiplozoon, Sindiplozoon)); and of the three suborders: (Discocotylinea, (Microcotylinea, Gastrocotylinea)). These intergeneric relationships were also supported by the skewness and principal component analyses. Our results show that nad2, atp6 and nad6 (fast-evolving) would be better candidates than cox1 (slow-evolving) for species identification and population genetics studies in Diplozoidae. Nucleotide bias and codon and amino acid usage patterns of the three diplozoid mitogenomes are more similar to cestodes and trematodes than to other Monogenean flatworms. This unusual mutational bias was reflected in disproportionately long branches in the phylogram. Our study offsets the scarcity of molecular data for the subclass Polyopisthocotylea to some extent, and might provide important new insights into the evolutionary history of the three genera and three suborders.
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Sequencing of the complete mitochondrial genome of a fish-parasitic flatworm Paratetraonchoides inermis (Platyhelminthes: Monogenea): tRNA gene arrangement reshuffling and implications for phylogeny.
Parasites & vectors, 2017Co-Authors: Dong Zhang, Hong Zou, Ivan Jakovlić, Jin Zhang, Rong Chen, Gui T. WangAbstract:Paratetraonchoides inermis (Monogenea: Tetraonchoididae) is a flatworm parasitising the gills of uranoscopid fishes. Its morphological characteristics are ambiguous, and molecular data have never been used to study its phylogenetic relationships, which makes its taxonomic classification controversial. Also, several decades of unsuccessful attempts to resolve the relationships within the Monogenea present a strong indication that morphological datasets may not be robust enough to be used to infer evolutionary histories. As the use of molecular data is currently severely limited by their scarcity, we have sequenced and characterized the complete mitochondrial (mt) genome of P. inermis. To investigate its phylogenetic position, we performed phylogenetic analyses using Bayesian inference and maximum likelihood approaches using concatenated amino acid sequences of all 12 protein-coding genes on a dataset containing all available Monogenean mt genomes. The circular mt genome of P. inermis (14,654 bp) contains the standard 36 genes: 22 tRNAs, two rRNAs, 12 protein-encoding genes (PCGs; Atp8 is missing) and a major non-coding region (mNCR). All genes are transcribed from the same strand. The A + T content of the whole genome (82.6%), as well as its elements, is the highest reported among the Monogeneans thus far. Three tRNA-like cloverleaf structures were found in mNCR. Several results of the phylogenomic analysis are in disagreement with previously proposed relationships: instead of being closely related to the Gyrodactylidea, Tetraonchidea exhibit a phylogenetic affinity with the Dactylogyridea + Capsalidea clade; and the order Capsalidea is neither basal within the subclass Monopisthocotylea, nor groups with the Gyrodactylidea, but instead forms a sister clade with the Dactylogyridea. The mt genome of P. inermis exhibits a unique gene order, with an extensive reorganization of tRNAs. Monogenea exhibit exceptional gene order plasticity within the Neodermata. This study shows that gene order within monopisthocotylid mt genomes is evolving at uneven rates, which creates misleading evolutionary signals. Furthermore, our results indicate that all previous attempts to resolve the evolutionary history of the Monogenea may have produced at least partially erroneous relationships. This further corroborates the necessity to generate more molecular data for this group of parasitic animals.
Martin Kašný - One of the best experts on this subject based on the ideXlab platform.
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Molecular communication between the Monogenea and fish immune system.
Fish & shellfish immunology, 2020Co-Authors: Jana Ilgová, Jiří Salát, Martin KašnýAbstract:Abstract Monogeneans parasitise mainly the outer structures of fish, such as the gills, fins, and skin, that is, tissues covered with a mucous layer. While attached by sclerotised structures to host's surface, Monogeneans feed on its blood or epidermal cells and mucus. Besides being a rich source of nutrients, these tissues also contain humoral immune factors and immune cells, which are ready to launch defence mechanisms against the tegument or gastrointestinal tract of these invaders. The exploitation of hosts' resources by the Monogenea must, therefore, be accompanied by suppressive and immunomodulatory mechanisms which protect the parasites against attacks by host immune system. Elimination of hosts' cytotoxic molecules and evasion of host immune response is often mediated by proteins secreted by the parasites. The aim of this review is to summarise existing knowledge on fish immune responses against Monogeneans. Results gleaned from experimental infections illustrate the various interactions between parasites and the innate and adaptive immune system of the fish. The involvement of Monogenean molecules (mainly inhibitors of peptidases) in molecular communication with host immune system is discussed.
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laser capture microdissection in combination with mass spectrometry approach to characterization of tissue specific proteomes of eudiplozoon nipponicum Monogenea polyopisthocotylea
PLOS ONE, 2020Co-Authors: Pavel Roudnický, David Potěšil, Milan Gelnar, Zbyněk Zdrahal, Martin KašnýAbstract:Eudiplozoon nipponicum (Goto, 1891) is a hematophagous Monogenean ectoparasite which inhabits the gills of the common carp (Cyprinus carpio). Heavy infestation can lead to anemia and in conjunction with secondary bacterial infections cause poor health and eventual death of the host. This study is based on an innovative approach to protein localization which has never been used in parasitology before. Using laser capture microdissection, we dissected particular areas of the parasite body without contaminating the samples by surrounding tissue and in combination with analysis by mass spectrometry obtained tissue-specific proteomes of tegument, intestine, and parenchyma of our model organism, E. nipponicum. We successfully verified the presence of certain functional proteins (e.g. cathepsin L) in tissues where their presence was expected (intestine) and confirmed that there were no traces of these proteins in other tissues (tegument and parenchyma). Additionally, we identified a total of 2,059 proteins, including 72 peptidases and 33 peptidase inhibitors. As expected, the greatest variety was found in the intestine and the lowest variety in the parenchyma. Our results are significant on two levels. Firstly, we demonstrated that one can localize all proteins in one analysis and without using laboratory animals (antibodies for immunolocalization of single proteins). Secondly, this study offers the first complex proteomic data on not only the E. nipponicum but within the whole class of Monogenea, which was from this point of view until recently neglected.
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Diplozoons (Monogenea): what is the molecular base of theirinteraction with the host?
2017Co-Authors: Martin Kašný, Jiří Vorel, Pavel Roudnický, Jana Ilgová, Hana Dvořáková, Lucie Jedličková, Libor Mikeš, Dagmar Jirsová, Hynek Strnad, Roman LeontovyčAbstract:The representatives from the class Monogenea are predominantly ectoparasites of fish. We adopted the experimental organisms - Eudiplozoon nipponicum (Diplozoidae, Heteronchoinea); a blood-feeding Monogenean inhabiting gills of common carp (Cyprinus carpio). In contrast to the other groups of platyhelminths, the identity of genes, the level of their expression and spectrum of functional protein molecules produced by these parasites are very limited. The pyrosequencing methodology (454/Roche, MiSeq/HiSeq) enabled us to generate robust genomic/trancriptomic data and combined them with the results of comprehensive mass spectrometry analysis (Orbitrap-Elite MS System) of excretory-secretory products isolated from the adult worms. The pipelines of bioinformatic data processing were optimized and number of functional molecules was annotated. The reached platform currently represents significant source of information available for further experimental research; up to now at least six functional protein molecules (peptidases and their inhibitors) have been molecularly / biochemically / immunochemically characterized.
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Monogenea: Parasites of fish and their unknown molecules
2017Co-Authors: Jiří Vorel, Pavel Roudnický, Milan Gelnar, Martin KašnýAbstract:The majority of known Monogenean species are ectoparasites of fish with monoxenous life cycle in freshwater or marine ecosystems. Some species are of high economic importance, they can be highly pathogenic to fish, which can result in losses in aquaculture. In contrast to these facts there is almost nothing known about the molecular nature of the interactions with fish hosts and functions of particular Monogeneans bioactive molecules. In a first part of our pilot study of Monogeneans molecules we adopted the NGS techniques in order to get the high quality “Monogenean-polyopisthocotylean genome/transcriptome matrix”. In a second part of our study this platform was used for the identification of the Monogeneans´ dominant protein molecules followed by their further molecular/biochemical characterization. We adopted experimental organism Eudiplozoon nipponicum (Platyhelminthes, Monogenea) in order to obtain high quality genome, transcriptome and proteome for further annotation, development of robust gene/protein muster platform for this group of organisms. Subsequently, we used this dataset in combination with bioinformatics approach enable in silico determination of antigenic proteins - vaccine candidates. In addition to the bioinformatics analyses we performed mass spectrometric identification of particular protein compounds in excretory-secretory products from E. nipponicum in order to confirm the presence of previously predicted antigenic molecules. Finally, some of the predicted molecules have been prepared in recombinant form and characterized (serpins, cystatins).
Dong Zhang - One of the best experts on this subject based on the ideXlab platform.
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mitochondrial genomes of two diplectanids platyhelminthes Monogenea expose paraphyly of the order dactylogyridea and extensive trna gene rearrangements
Parasites & Vectors, 2018Co-Authors: Dong Zhang, Hong Zou, Jin Zhang, Rong Chen, Ivan Jakovlic, Gui T. WangAbstract:Recent mitochondrial phylogenomics studies have reported a sister-group relationship of the orders Capsalidea and Dactylogyridea, which is inconsistent with previous morphology- and molecular-based phylogenies. As Dactylogyridea mitochondrial genomes (mitogenomes) are currently represented by only one family, to improve the phylogenetic resolution, we sequenced and characterized two dactylogyridean parasites, Lamellodiscus spari and Lepidotrema longipenis, belonging to a non-represented family Diplectanidae. The L. longipenis mitogenome (15,433 bp) contains the standard 36 flatworm mitochondrial genes (atp8 is absent), whereas we failed to detect trnS1, trnC and trnG in L. spari (14,614 bp). Both mitogenomes exhibit unique gene orders (among the Monogenea), with a number of tRNA rearrangements. Both long non-coding regions contain a number of different (partially overlapping) repeat sequences. Intriguingly, these include putative tRNA pseudogenes in a tandem array (17 trnV pseudogenes in L. longipenis, 13 trnY pseudogenes in L. spari). Combined nucleotide diversity, non-synonymous/synonymous substitutions ratio and average sequence identity analyses consistently showed that nad2, nad5 and nad4 were the most variable PCGs, whereas cox1, cox2 and cytb were the most conserved. Phylogenomic analysis showed that the newly sequenced species of the family Diplectanidae formed a sister-group with the Dactylogyridae + Capsalidae clade. Thus Dactylogyridea (represented by the Diplectanidae and Dactylogyridae) was rendered paraphyletic (with high statistical support) by the nested Capsalidea (represented by the Capsalidae) clade. Our results show that nad2, nad5 and nad4 (fast-evolving) would be better candidates than cox1 (slow-evolving) for species identification and population genetics studies in the Diplectanidae. The unique gene order pattern further suggests discontinuous evolution of mitogenomic gene order arrangement in the Class Monogenea. This first report of paraphyly of the Dactylogyridea highlights the need to generate more molecular data for Monogenean parasites, in order to be able to clarify their relationships using large datasets, as single-gene markers appear to provide a phylogenetic resolution which is too low for the task.
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three new diplozoidae mitogenomes expose unusual compositional biases within the Monogenea class implications for phylogenetic studies
BMC Evolutionary Biology, 2018Co-Authors: Dong Zhang, Hong Zou, Jin Zhang, Rong Chen, Ivan Jakovlic, Gui T. WangAbstract:As the topologies produced by previous molecular and morphological studies were contradictory and unstable (polytomy), evolutionary relationships within the Diplozoidae family and the Monogenea class (controversial relationships among the Discocotylinea, Microcotylinea and Gastrocotylinea suborders) remain unresolved. Complete mitogenomes carry a relatively large amount of information, sufficient to provide a much higher phylogenetic resolution than traditionally used morphological traits and/or single molecular markers. However, their implementation is hampered by the scarcity of available Monogenean mitogenomes. Therefore, we sequenced and characterized mitogenomes belonging to three Diplozoidae family species, and conducted comparative genomic and phylogenomic analyses for the entire Monogenea class. Taxonomic identification was inconclusive, so two of the species were identified merely to the genus level. The complete mitogenomes of Sindiplozoon sp. and Eudiplozoon sp. are 14,334 bp and 15,239 bp in size, respectively. Paradiplozoon opsariichthydis (15,385 bp) is incomplete: an approximately 2000 bp-long gap within a non-coding region could not be sequenced. Each genome contains the standard 36 genes (atp8 is missing). G + T content and the degree of GC- and AT-skews of these three mitogenome (and their individual elements) were higher than in other Monogeneans. nad2, atp6 and nad6 were the most variable PCGs, whereas cox1, nad1 and cytb were the most conserved. Mitochondrial phylogenomics analysis, conducted using concatenated amino acid sequences of all PCGs, indicates that evolutionary relationships of the three genera are: (Eudiplozoon, (Paradiplozoon, Sindiplozoon)); and of the three suborders: (Discocotylinea, (Microcotylinea, Gastrocotylinea)). These intergeneric relationships were also supported by the skewness and principal component analyses. Our results show that nad2, atp6 and nad6 (fast-evolving) would be better candidates than cox1 (slow-evolving) for species identification and population genetics studies in Diplozoidae. Nucleotide bias and codon and amino acid usage patterns of the three diplozoid mitogenomes are more similar to cestodes and trematodes than to other Monogenean flatworms. This unusual mutational bias was reflected in disproportionately long branches in the phylogram. Our study offsets the scarcity of molecular data for the subclass Polyopisthocotylea to some extent, and might provide important new insights into the evolutionary history of the three genera and three suborders.
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Sequencing of the complete mitochondrial genome of a fish-parasitic flatworm Paratetraonchoides inermis (Platyhelminthes: Monogenea): tRNA gene arrangement reshuffling and implications for phylogeny.
Parasites & vectors, 2017Co-Authors: Dong Zhang, Hong Zou, Ivan Jakovlić, Jin Zhang, Rong Chen, Gui T. WangAbstract:Paratetraonchoides inermis (Monogenea: Tetraonchoididae) is a flatworm parasitising the gills of uranoscopid fishes. Its morphological characteristics are ambiguous, and molecular data have never been used to study its phylogenetic relationships, which makes its taxonomic classification controversial. Also, several decades of unsuccessful attempts to resolve the relationships within the Monogenea present a strong indication that morphological datasets may not be robust enough to be used to infer evolutionary histories. As the use of molecular data is currently severely limited by their scarcity, we have sequenced and characterized the complete mitochondrial (mt) genome of P. inermis. To investigate its phylogenetic position, we performed phylogenetic analyses using Bayesian inference and maximum likelihood approaches using concatenated amino acid sequences of all 12 protein-coding genes on a dataset containing all available Monogenean mt genomes. The circular mt genome of P. inermis (14,654 bp) contains the standard 36 genes: 22 tRNAs, two rRNAs, 12 protein-encoding genes (PCGs; Atp8 is missing) and a major non-coding region (mNCR). All genes are transcribed from the same strand. The A + T content of the whole genome (82.6%), as well as its elements, is the highest reported among the Monogeneans thus far. Three tRNA-like cloverleaf structures were found in mNCR. Several results of the phylogenomic analysis are in disagreement with previously proposed relationships: instead of being closely related to the Gyrodactylidea, Tetraonchidea exhibit a phylogenetic affinity with the Dactylogyridea + Capsalidea clade; and the order Capsalidea is neither basal within the subclass Monopisthocotylea, nor groups with the Gyrodactylidea, but instead forms a sister clade with the Dactylogyridea. The mt genome of P. inermis exhibits a unique gene order, with an extensive reorganization of tRNAs. Monogenea exhibit exceptional gene order plasticity within the Neodermata. This study shows that gene order within monopisthocotylid mt genomes is evolving at uneven rates, which creates misleading evolutionary signals. Furthermore, our results indicate that all previous attempts to resolve the evolutionary history of the Monogenea may have produced at least partially erroneous relationships. This further corroborates the necessity to generate more molecular data for this group of parasitic animals.
Leslie A. Chisholm - One of the best experts on this subject based on the ideXlab platform.
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Decacotyle cairae n. sp. (Monogenea: Monocotylidae) from the gills of Pastinachus sp. (Elasmobranchii: Dasyatidae) from the South China Sea off Sarawak, Borneo, Malaysia
Systematic Parasitology, 2005Co-Authors: Leslie A. Chisholm, Ian D. WhittingtonAbstract:Decacotyle cairae n. sp. (Monogenea: Monocotylidae) is described from the gills of an unidentified species of Pastinachus collected in the South China Sea off Sematan and Mukah, Sarawak, Borneo, Malaysia. D. cairae can be distinguished from the other six members of the genus by the presence of two simple unsclerotised accessory structures on the dorsal surface of the haptor in combination with a long, narrow, looping male copulatory organ. The host specimens of Pastinachus collected in Borneo also appear to be a new species and the Monogenean data support this conclusion. A key to species of Decacotyle is given and their host-specificity is discussed.
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Empruthotrema stenophallus n. sp. (Monogenea: Monocotylidae) from the nasal tissue of Dasyatis kuhlii (Dasyatidae) from Sabah, Borneo, Malaysia.
The Journal of parasitology, 2005Co-Authors: Leslie A. Chisholm, Ian D. WhittingtonAbstract:Empruthotrema stenophallus n. sp. (Monogenea: Monocotylidae) is described from specimens from the nasal tissue of the blue-spotted maskray Dasyatis kuhlii (Muller and Henle, 1841) collected in shallow waters off Pulau Banggi and Pulau Mabul, Sabah, Borneo, Malaysia. This is the first Monogenean species to be described from an elasmobranch collected from Sabah. E. stenophallus can be distinguished from the other 6 members of the genus by the morphology of the sclerotized male copulatory organ, which is narrow, short, and distally tapered. E. dasyatidis Whittington and Kearn, 1992, previously documented from the nasal tissue of several of elasmobranch species from Australia, is recorded from 8 host species distributed around Malaysian Borneo. These represent new host and locality records for this monocotylid. The difficulties in identifying species of Empruthotrema and the apparent lack of host specificity by some members of the genus are discussed.
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Diversity in the Monogenea and Digenea: does lifestyle matter?
International Journal for Parasitology, 2002Co-Authors: Thomas H. Cribb, Leslie A. Chisholm, Rodney A BrayAbstract:If the cestodes are excluded, then the parasitic platyhelminths of fishes divide neatly into the external and monoxenous Monogenea and the internal and heteroxenous Digenea. Both groups have apparently had long associations of coevolution, host switching and adaptation with fishes and have become highly successful in their respective habitats. Current estimates of species richness for the two groups suggest that they may be remarkably similar. Here we consider the nature of the diversity of the Monogenea. and Digenea of fishes in terms of richness of species and higher taxa to determine what processes may be responsible for observed differences. The Monogenea includes at least two super-genera (Dactylogyrus and Gyrodactylus) each of which has hundreds of species, no comparable genera are found in the Digenea. Possible reasons for this difference include the higher host specificity of Monogeneans and their shorter generation Lime. If allowance is made for the vagaries of taxonomic 'lumping' and 'splitting', then there are probably comparable numbers of families of Monogeneans and digeneans in fishes. However, the nature of the families differ profoundly. Richness in higher taxa (families) in the Digenea is explicable in terms of processes that appear to have been unimportant in the Monogenea. Readily identifiable sources of diversity in the Digenea are: recolonisation of fishes by taxa that arose in association with tetrapods; adoption of new sites within hosts; adoption of new diets and feeding mechanisms; adaptations relating to the exploitation of ecologically similar groups of fishes and second intermediate hosts; and adaptations relating to the exploitation of phylogenetic lineages of molluscs. In contrast, most higher- level Monogenean diversity (other than that associated with the subclasses) relates principally to morphological specialisation for attachment by the haptor. (C) 2002 Australian Society for Parasitology Inc. Published by Elsevier Science Ltd. All rights reserved.
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Egg hatching in 3 species of monocotylid Monogenean parasites from the shovelnose ray Rhinobatos typus at Heron Island, Australia.
Parasitology, 2000Co-Authors: Leslie A. Chisholm, Ian D. WhittingtonAbstract:Eggs of Neoheterocotyle rhinobatidis, Troglocephalus rhinobatidis and Merizocotyle icopae (Monogenea: Monocotylidae) from the shovelnose ray Rhinobatos typus (Rhinobatidae) have a distinct hatching pattern linked to light periodicity. Larvae of these 3 Monogenean species emerge only during daylight when exposed to natural illumination or when incubated in alternating 12 h periods of light and dark (light on 06.00 h, light off 18.00 h). N. rhinobatidis larvae emerge with a distinct peak during the first 2 h of light; this peak is not as pronounced in T. rhinobatidis or M. icopae. Eggs of N. rhinobatidis incubated in a reverse light/dark cycle (light on 18.00 h, light off 06.00 h) hatched only during periods of illumination, again with a peak during the first 2 h of light. Evidence suggests that the hatching patterns observed in all 3 species represent true circadian rhythms because eggs incubated in 24 h light or 24 h dark conditions continued to hatch with a rhythm. Shadows, disturbance and host tissue did not promote hatching in N. rhinobatidis or T. rhinobatidis but there were indications that host tissue may promote hatching in M. icopae. The hatching patterns observed are discussed with respect to their adaptive responses to host behaviour and predation pressure.
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The larvae of Monogenea (Platyhelminthes)
Advances in Parasitology, 1999Co-Authors: Ian D. Whittington, Leslie A. Chisholm, Klaus RohdeAbstract:Abstract There has been no comprehensive review of the infective larval stage (oncomiracidium) in the direct life-cycle of Monogeneans since Llewellyn (1963, 1968). In the last 30 years, knowledge of the general anatomy and morphology of oncomiracidia has increased significantly as has information on swimming behaviour and egg-hatching strategies that may enhance chances of host infection. Nevertheless, oncomiracidia are known for only a small proportion of Monogenean species described. This review consolidates established, and summarizes new, knowledge since Llewellyn's work and integrates light- and electron-microscopy studies including unpublished data. Currently there is considerable debate, fuelled largely by phylogenetic studies using molecular techniques, about whether or not the class Monogenea (comprising subclasses Monopisthocotylea and Polyopistho-cotylea) is monophyletic. This challenges established views that Monopisthocotylea and Polyopisthocotylea form a single clade based on two larval characters: two pairs of rhabdomeric eyes; three bands of ciliated cells. In an attempt to reveal further synapomorphies for the entire Monogenea (or provide evidence against its monophyly) or possibly for the Monopisthocotylea and Polyopisthocotylea only, we review the following larval features: haptoral sclerites; ciliated cells; epidermis; terminal globule; gland, proto-nephridial and nervous systems; sense organs; digestive tract; parenchyma; and behaviour. Conclusions are equivocal but indicate that further larval studies, especially ultrastructural, are necessary to assess: to presence or absence of ‘false’ vertical rootlets of epidermal cilia; tapering epidermal cilia; the protonephridial system; the presence or absence of a terminal globule; glands and their secretions; and the embryology and chemical composition of haptoral sclerites. Future integration of light- and electron-microscopy studies are likely to be particularly informative.
