Paradiplozoon
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Paradiplozoon hemiculteri (Ling, 1973), a member of the Diplozoidae, parasitizes the gills of Asian fish. Not only is the type material unavailable for this species, the original description was poor and somewhat conflicting, and adequate molecular data were not available. What is more, the available morphological and molecular data are inconsistent and fluctuate significantly. Here, we present a redescription of P. hemiculteri based on morphological and molecular data from new isolates collected from the type host, the sharpbelly Hemiculter leucisculus (Basilewsky, 1855), captured at the neotype locality (Shaoguan, Guangdong Province, southern China); a neotype for P. hemiculteri was designated from this collection. The length and width of the body, buccal suckers, pharynx, attachment clamps, sickle and the central hook handle were all measured and the shape of the anterior and posterior part of the median plate and anterior and posterior joining sclerites accurately documented. Phylogenetic analyses based on the sequences of the second rDNA internal transcribed spacer (ITS2) indicated that all new samples clustered together and differed clearly from sequences attributed to P. hemiculteri, which are deposited in GenBank. Our results confirm that P. hemiculteri is the only diplozoid that has demonstrably been found on the gills of H. leucisculus to date.
- MeSH
- Cyprinidae parazitologie MeSH
- DNA helmintů chemie MeSH
- fylogeneze * MeSH
- infekce červy třídy Trematoda epidemiologie parazitologie veterinární MeSH
- mezerníky ribozomální DNA chemie MeSH
- nemoci ryb epidemiologie parazitologie MeSH
- Trematoda klasifikace genetika izolace a purifikace MeSH
- žábry parazitologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Čína epidemiologie MeSH
Paradiplozoon homoion is a representative of blood-feeding ectoparasites from the family Diplozoidae (Polyopisthocotylea, Monogenea). Although these worms have been the subject of numerous taxonomical, phylogenetic and ecological studies, the ultrastructure of the alimentary system and related structures, as well as the mechanisms of essential processes like fish blood digestion, remain mostly unknown. Our observation of P. homoion using a transmission electron microscopy (TEM) revealed two main types of digestive cells-U-shaped haematin cells and connecting syncytium. Particular structures such as mouth cavity with specialised receptors, two oval-shaped muscular buccal suckers, pharynx surrounded with the glandular cells, oesophagus, the intestinal caeca with intact erythrocytes in the lumen, the apical pinocytotic fibrous surface complex and haematin vesicles of U-shaped cells have been shown in detail. According to our results, the P. homoion is degrading the blood components predominantly intracellularly.
Diplozoidae (Monogenea) are blood-feeding freshwater fish gill ectoparasites with extraordinary body architecture and a unique sexual behaviour in which two larval worms fuse and transform into one functioning individual. In this study, we describe the body organisation of Paradiplozoon homoion adult stage using a combined approach of confocal laser scanning and electron microscopy, with emphasis on the forebody and hindbody. Special attention is given to structures involved in functional adaptation to ectoparasitism, i.e. host searching, attachment and feeding/metabolism. Our observations indicate clear adaptations for blood sucking, with a well-innervated mouth opening surrounded by sensory structures, prominent muscular buccal suckers and a pharynx. The buccal cavity surface is covered with numerous tegumentary digitations that increase the area in contact with host tissue and, subsequently, with its blood. The buccal suckers and the well-innervated haptor (with sclerotised clamps controlled by noticeable musculature) cooperate in attaching to and moving over the host. Putative gland cells accumulate in the region of apical circular structures, pharynx area and in the haptor middle region. Paired club-shaped sacs lying laterally to the pharynx might serve as secretory reservoirs. Furthermore, we were able to visualise the body wall musculature, including peripheral innervation, the distribution of uniciliated sensory structures essential for reception of external environmental information, and flame cells involved in excretion. Our results confirm in detail that P. homoion displays a range of sophisticated adaptations to an ectoparasitic life style, characteristic for diplozoid monogeneans.
- MeSH
- infestace ektoparazity parazitologie MeSH
- interakce hostitele a parazita MeSH
- konfokální mikroskopie MeSH
- mikroskopie elektronová rastrovací MeSH
- ploštěnci anatomie a histologie patogenita MeSH
- ryby parazitologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND: Species of Diplozoon Palombi, 1949 (Monogenea: Diplozoidae) are blood-feeding ectoparasites mainly parasitising the gills of cyprinid fishes. Although these parasites have been the subject of numerous taxonomic, phylogenetic and ecological studies, the ultrastructure of the surface and haptor attachment structures remains almost unknown. In this study, we used transmission electron microscopy to examine the ultrastructure of attachment clamps and neodermal surface of Paradiplozoon homoion (Bychowsky & Nagibina, 1959), family Diplozoidae Palombi, 1949, thereby broadening our knowledge of platyhelminth biology. RESULTS: The hindbody surface of P. homoion is distinctly ridged, each ridge being supported by several muscle fibers and equipped with scales on the surface plasma membrane. Such structures have not been recorded previously in species of the family Diplozoidae. Comparisons of the surface structure of different body parts revealed slight differences in the thickness and number of organelles. Each of the clamps has a flattened bowl-like structure composed of sclerites, movable skeletal-like structures that are anchored by robust, radially oriented muscle bundles. The base of the posterior median plate sclerites is equipped with glandular cells possessing secretory vesicles. CONCLUSION: This study brings detailed ultrastructural data for the surface and haptoral attachment clamps of P. homoion and provides new insights into the ultrastructure of Diplozoidae. Glandular cells at the base of the attachment clamps responsible for sclerite development in diplozoid species were observed for the first time. Our findings support the hypothesis that the structure of particular neodermal compartments is similar within the Platyhelminthes. On the other hand, the diplozoid glandular system and the mechanism of sclerite development clearly merits further attention.
- MeSH
- Cyprinidae parazitologie MeSH
- fylogeneze MeSH
- infekce červy třídy Trematoda parazitologie veterinární MeSH
- nemoci ryb parazitologie MeSH
- transmisní elektronová mikroskopie MeSH
- Trematoda izolace a purifikace fyziologie ultrastruktura MeSH
- žábry parazitologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- MeSH
- Cyprinidae parazitologie MeSH
- finanční podpora výzkumu jako téma MeSH
- infekce červy třídy Trematoda veterinární MeSH
- Trematoda genetika klasifikace MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- srovnávací studie MeSH
- Geografické názvy
- Česká republika MeSH
- MeSH
- Cyprinidae anatomie a histologie parazitologie MeSH
- ekosystém * MeSH
- infekce červy třídy Trematoda epidemiologie parazitologie veterinární MeSH
- kvalita vody * MeSH
- nemoci ryb epidemiologie parazitologie MeSH
- roční období * MeSH
- Trematoda fyziologie MeSH
- velikost těla MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Jihoafrická republika MeSH
The present study redescribes the monotypic genus Afrodiplozoon Khotenovski, 1981, a diplozooid parasite endemic to Africa, based on material collected during surveys carried out in the Limpopo Province, South Africa, from two cyprinid hosts Labeobarbus marequensis and Enteromius paludinosus. Morphometrical analysis of the composition of internal organs and attachment clamps, using light microscopy and scanning electron microscopy, provided details for the genus and species redescriptions. Posterior attachment apparatus can bear up the 15 pairs of the clamps with the first pair of clamps distinctly smaller and not fully developed. Molecular characterization of the second internal transcribed spacer (ITS2) rDNA and phylogenetic analysis revealed the position of Afrodiplozoon polycotyleus as a sister taxon to Paradiplozoon krugerense and Paradiplozoon bingolenisis, distant from other African representatives of the genus Paradiplozoon, Paradiplozoon vaaleense and Paradiplozoon ichtyoxanthon.
- MeSH
- Cyprinidae parazitologie MeSH
- infekce červy třídy Trematoda epidemiologie parazitologie MeSH
- mezerníky ribozomální DNA genetika MeSH
- mikroskopie elektronová rastrovací MeSH
- mikroskopie MeSH
- Trematoda anatomie a histologie klasifikace genetika ultrastruktura MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Jihoafrická republika MeSH
The present study has revealed new data on chromosome complements of diplozoid parasites, namely Diplozoon paradoxum from freshwater bream Abramis brama, Paradiplozoon bliccae from white bream Blicca bjoerkna, Paradiplozoon sapae from white-eye bream Ballerus sapa, and Paradiplozoon nagibinae from zope Ballerus ballerus. Particularly, D. paradoxum is characterized by four pairs (2n=8) of long (up to 22.1 μm) chromosomes: pairs 1, 2, and 3 are metacentric and pair 4 acrocentric. Karyotypes of three Paradiplozoon species are nearly identical in number and morphological classification of chromosomes, each comprising diploid number of 14 one-armed chromosomes of very similar length ranging up to 12.5 μm in P. bliccae, 9.2 μm in P. sapae, and 9.9 μm in P. nagibinae. All four species are similar in their total complement length, ranging from 64.4 to 50.4 μm. Interspecific differences were found in location of secondary constriction: it is situated on short arm of the 1st chromosome pair in D. paradoxum, on long arm of the 7th pair in P. bliccae and on long arm of the 4th pairs in P. sapae and P. nagibinae. Phylogenetic interrelationship within the diplozoids and hypothetic karyotype evolution is here discussed.
- MeSH
- buněčné jádro MeSH
- cestodózy parazitologie veterinární MeSH
- Cyprinidae parazitologie MeSH
- karyotypizace MeSH
- nemoci ryb parazitologie MeSH
- ploštěnci cytologie genetika izolace a purifikace MeSH
- žábry parazitologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
