Egg ultrastructure of the amabiliid cestode Tatria biremis Kowalewski, 1904 (Cyclophyllidea, Amabiliidae), with an emphasis on the oncospheral envelopes

2013 ◽  
Vol 58 (3) ◽  
Author(s):  
Vasyl Tkach ◽  
Zdzisław Świderski ◽  
Daniel Młocicki
Keyword(s):  
Cell Types ◽  
Life Cycles ◽  
Intermediate Hosts ◽  
Outer Envelope ◽  
Ultrastructural Studies ◽  
Egg Maturation ◽  
Ultrastructural Characteristics ◽  
Egg Envelopes ◽  
Host Infection ◽  
Inner Envelope

AbstractThis is the first report on the ultrastructure of eggs in the cestode family Amabiliidae Braun, 1900. The gravid proglottides of Tatria biremis easily detach from the strobila. Their thick-walled saccate uterus contains numerous rounded or oval eggs measuring about 30-32 μm in diameter. In the early preoncospheral phase, three primary embryonic envelopes are formed around the developing and differentiating embryos, namely: (1) vitelline capsule originating from vitellocyte material; (2) outer envelope formed by two macromeres, and (3) inner envelope originating from a fusion of three mesomeres. Thus, both the outer and inner envelopes of T. biremis eggs are cellular in origin and syncytial in nature. During egg maturation, the three primary embryonic envelopes undergo differentiation into fully formed oncospheral or egg envelopes. Most significant changes were observed in the inner envelope which becomes progressively subdivided into 3 sub-layers: the extra-embryophoral sub-layer, the embryophore, and the intra-embryophoral sub-layer, containing mesomere nuclei. The mature hexacanth is covered by a thin layer of the oncospheral tegument. Within the infective hexacanth larva, five cell types were distinguished: (1) a binucleated subtegumental cell; (2) U-shaped penetration gland; (3) nerve cells; (4) somatic cells representing the myocytons of both somatic and hook musculature, and (5) large germinative cells. Ultrastructural characteristics of T. biremis eggs are compared with those described in representatives of other cestode taxa. Since the functional ultrastructure of cestode egg envelopes is defined by multiple factors such as the type of life cycles, habitats and behaviour of the intermediate hosts, mode of the intermediate host infection, etc., ultrastructural studies of the greater diversity of cestodes are needed to obtain comparative data for fruitful analysis of cyclophyllidean cestode adaptations to their diverse life cycles.

Ultrastructural studies on egg envelopes surrounding the miracidia of Mediogonimus jourdanei Mas-Coma et Rocamora, 1978 (Digenea, Microphalloidea, Prosthogonimidae)

2010 ◽  
Vol 55 (3) ◽  
Author(s):  
Zdzisław Świderski ◽  
Abdoulaye Bakhoum ◽  
Daniel Młocicki ◽  
Jordi Miquel
Keyword(s):  
Electron Microscopy ◽  
Lipid Droplets ◽  
Freeze Substitution ◽  
High Pressure Freezing ◽  
Ultrastructural Studies ◽  
Transmission Electron ◽  
Egg Envelopes ◽  
Egg Shell ◽  
Means Of Transmission ◽  
Inner Envelope

AbstractThe intrauterine, mature and fully embryonated eggs of the prosthogonimid trematode Mediogonimus jourdanei Mas-Coma et Rocamora, 1978 were examined by means of transmission electron microscopy (TEM), using high pressure freezing, freeze substitution and infiltration with resin techniques. Each embryonated egg is composed of a miracidium surrounded by three envelopes: (1) the egg shell, (2) the outer and (3) inner envelopes. Egg envelopes play an important role in the protection, metabolism, storage of nutritive reserves and the general biology of the M. jourdanei egg. The inner envelope is characterised by large, flattened nuclei, and its syncytial cytoplasm contains a heavy accumulation of glycogen, lipid droplets, mitochondria and large vesicles. These traits indicate that this layer has the features of a metabolically-active syncytial layer with an energy storage capability. In the infective eggs observed before the hatching of the miracidium, areas of so-called “focal cytoplasmic degradation” were frequently observed, which may be involved in the autolytic process of all components of this envelopes.

Formation of the Paruterine Capsules and Embryonic Envelopes in Cylindrotaenia-Hickmani (Jones, 1985) (Cestoda, Nematotaeniidae)

1988 ◽  
Vol 36 (5) ◽  
pp. 545 ◽  
Author(s):  
MK Jones
Keyword(s):  
Electron Microscopy ◽  
Life Cycles ◽  
Outer Envelope ◽  
Capsule Formation ◽  
Cellular Processes ◽  
Sequence Of Events ◽  
Transmission Electron ◽  
Early Embryos ◽  
Outer Capsule ◽  
Inner Envelope

The development of embryonic envelopes and paruterine capsules in Cylindrotaenia hickmani (Jones 1985) Jones, 1987 were studied using transmission electron microscopy. The embryonic envelopes of C. hickmani form in a similar way to those of other cyclophyllideans. The extant embryonic envelopes in fully developed eggs are: the thin, featureless outer envelope; the inner envelope, which forms an oncospheral membrane; embryophore; and an electron-dense peripheral cytoplasmic layer that lies immediately internal to the external plasma membrane of the inner envelope. Processes of uterine epithelial cells envelop the outer capsule of early embryos. Both the uterine envelope and outer capsule are lost as eggs develop. Paruterine organs are complex, paired structures that form lipid and flattened cellular processes for inclusion within paruterine capsules. Paruterine capsules are complex parenchymal structures containing eggs and the products of the paruterine organs. The possession of such complex paruterine envelopes suggests that the life cycles of nematotaeniids are terrestrial. The sequence of events in paruterine capsule formation in nematotaeniids is unlike that seen in other cyclophyllidean groups with paruterine capsules and it is unlikely that nematotaeniids are closely related to such cestodes.

Ultrastructure of Cercarial Tails

1974 ◽  
Vol 32 ◽  
pp. 180-181
Author(s):  
Richard S. Demaree ◽  
Donald M. Wootton
Keyword(s):  
Schistosoma Japonicum ◽  
Intermediate Hosts ◽  
Suitable Host ◽  
Ultrastructural Studies ◽  
Tail Structure

Cercariae (juvenile trematodes with tails) emerge from mollusk intermediate hosts and swim toward definitive hosts or encystment objects. The locomotor power is furnished by the tail. Upon reaching a suitable host or encystment object, the tail is cast off and the cercariae penetrate and/or encyst. Ultrastructural studies of cercariae are sparse. There is even lessUltrastructural studies of cercariae are sparse. There is even less information about the tail structure; and body-to-tail morphology has been documented only for Acanthatrium oregonense and Schistosoma japonicum.

scholarly journals Leeches as the intermediate host for strigeid trematodes: genetic diversity and taxonomy of the genera Australapatemon Sudarikov, 1959 and Cotylurus Szidat, 1928

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Ewa Pyrka ◽  
Gerard Kanarek ◽  
Grzegorz Zaleśny ◽  
Joanna Hildebrand
Keyword(s):  
Intermediate Host ◽  
Life Cycles ◽  
Coi Gene ◽  
Small Rivers ◽  
Ecological Niches ◽  
Its2 Region ◽  
28S Rrna ◽  
Intermediate Hosts ◽  
Internal Transcribed Spacer Region ◽  
Wide Range

Abstract Background Leeches (Hirudinida) play a significant role as intermediate hosts in the circulation of trematodes in the aquatic environment. However, species richness and the molecular diversity and phylogeny of larval stages of strigeid trematodes (tetracotyle) occurring in this group of aquatic invertebrates remain poorly understood. Here, we report our use of recently obtained sequences of several molecular markers to analyse some aspects of the ecology, taxonomy and phylogeny of the genera Australapatemon and Cotylurus, which utilise leeches as intermediate hosts. Methods From April 2017 to September 2018, 153 leeches were collected from several sampling stations in small rivers with slow-flowing waters and related drainage canals located in three regions of Poland. The distinctive forms of tetracotyle metacercariae collected from leeches supplemented with adult Strigeidae specimens sampled from a wide range of water birds were analysed using the 28S rDNA partial gene, the second internal transcribed spacer region (ITS2) region and the cytochrome c oxidase (COI) fragment. Results Among investigated leeches, metacercariae of the tetracotyle type were detected in the parenchyma and musculature of 62 specimens (prevalence 40.5%) with a mean intensity reaching 19.9 individuals. The taxonomic generic affiliation of metacercariae derived from the leeches revealed the occurrence of two strigeid genera: Australapatemon Sudarikov, 1959 and Cotylurus Szidat, 1928. Phylogenetic reconstructions based on the partial 28S rRNA gene, ITS2 region and partial COI gene confirmed the separation of the Australapatemon and Cotylurus clades. Taking currently available molecular data and our results into consideration, recently sequenced tetracotyle of Australapatemon represents most probably Au. minor; however, unclear phylogenetic relationships between Au. burti and Au. minor reduce the reliability of this conclusion. On the other hand, on the basis of the obtained sequences, supplemented with previously published data, the metacercariae of Cotylurus detected in leeches were identified as two species: C. strigeoides Dubois, 1958 and C. syrius Dubois, 1934. This is the first record of C. syrius from the intermediate host. Conclusions The results of this study suggest the separation of ecological niches and life cycles between C. cornutus (Rudolphi, 1808) and C. strigeoides/C. syrius, with potential serious evolutionary consequences for a wide range of host–parasite relationships. Moreover, phylogenetic analyses corroborated the polyphyletic character of C. syrius, the unclear status of C. cornutus and the separate position of Cotylurus raabei Bezubik, 1958 within Cotylurus. The data demonstrate the inconsistent taxonomic status of the sequenced tetracotyle of Australapatemon, resulting, in our opinion, from the limited availability of fully reliable, comparative sequences of related taxa in GenBank.

scholarly journals Molecular data reshape our understanding of the life cycles of three digeneans (Monorchiidae and Gymnophallidae) infecting the bivalve, Donax variabilis: it’s just a facultative host!

Parasite ◽  
2021 ◽  
Vol 28 ◽  
pp. 34
Author(s):  
Kristina M. Hill-Spanik ◽  
Claudia Sams ◽  
Vincent A. Connors ◽  
Tessa Bricker ◽  
Isaure de Buron
Keyword(s):  
Gulf Of Mexico ◽  
Intermediate Host ◽  
Atlantic Coast ◽  
The United States ◽  
Life Cycles ◽  
Intermediate Hosts ◽  
Larval Stages ◽  
Complete Life Cycle ◽  
Morphological Criteria ◽  
Donax Variabilis

The coquina, Donax variabilis, is a known intermediate host of monorchiid and gymnophallid digeneans. Limited morphological criteria for the host and the digeneans’ larval stages have caused confusion in records. Herein, identities of coquinas from the United States (US) Atlantic coast were verified molecularly. We demonstrate that the current GenBank sequences for D. variabilis are erroneous, with the US sequence referring to D. fossor. Two cercariae and three metacercariae previously described in the Gulf of Mexico and one new cercaria were identified morphologically and molecularly, with only metacercariae occurring in both hosts. On the Southeast Atlantic coast, D. variabilis’ role is limited to being a facultative second intermediate host, and D. fossor, an older species, acts as both first and second intermediate hosts. Sequencing demonstrated 100% similarities between larval stages for each of the three digeneans. Sporocysts, single tail cercariae, and metacercariae in the incurrent siphon had sequences identical to those of monorchiid Lasiotocus trachinoti, for which we provide the complete life cycle. Adults are not known for the other two digeneans, and sequences from their larval stages were not identical to any in GenBank. Large sporocysts, cercariae (Cercaria choanura), and metacercariae in the coquinas’ foot were identified as Lasiotocus choanura (Hopkins, 1958) n. comb. Small sporocysts, furcocercous cercariae, and metacercariae in the mantle were identified as gymnophallid Parvatrema cf. donacis. We clarify records wherein authors recognized the three digenean species but confused their life stages, and probably the hosts, as D. variabilis is sympatric with cryptic D. texasianus in the Gulf of Mexico.

Parthenogenesis and asexual multiplication among parasitic platyhelminths

Parasitology ◽  
1983 ◽  
Vol 86 (4) ◽  
pp. 121-160 ◽  
Author(s):  
P. J. Whitfield ◽  
N. A. Evans
Keyword(s):  
Stem Cells ◽  
Population Expansion ◽  
Life Cycles ◽  
Intermediate Hosts ◽  
Present Evidence ◽  
Stage Of Development ◽  
The Family ◽  
Asexual Multiplication ◽  
Modes Of Existence ◽  
First Intermediate Host

SUMMARYAmong flatworms with parasitic and commensal modes of existence, parthenogenesis and asexual multiplication appear to be largely confined to the Digenea and Cestoda, the only parasitic platyhelminths that routinely utilize indirect life-cycles. Parthenogenesis is apparently restricted to a minority of adult digeneans and cestodes inhabiting their final hosts, and a survey is made of the particular modes of parthenogenesis (i.e. apomictic, automictic and generative) which are employed by such adults. Asexual (amictic) multiplication, in the form of fissioning, is demonstrated by young adults of the cyclophyllidean cestode, Mesoces-toides corti, but is otherwise not exhibited by adult cestodes or digeneans, other than in the perplexing phenomenon of proglottid formation in polyzoic tapeworms. Secondary multiplication is of ubiquitous occurrence in digenean life-cycles in the form of the proliferation which takes place within sporocysts and rediae (germinal sacs) located in the first intermediate host. The controversy concerning the nature of this multiplication is reconsidered in the context of recent findings which have centred on cellular aspects. On the basis of present evidence germinal sac multiplication should be regarded as an asexual rather than a parthen-ogenetic process. The cestode asexual multiplication which occurs in intermediate hosts is a function of the metacestode stage of development. Metacestode proliferation is only known from about 20 species and 6 families of polyzoic cestodes with approximately half the described instances occurring in the family Taeniidae. The organization of these proliferative metacestodes, findings concerning their totipotent stem cells and the ontogeny of buds and new scolices are all reviewed. Finally, the capacity for population expansion of multiplicative larval digeneans and metacestodes are compared, while the ecological roles and the genetical consequences of both parthenogenesis and amictic multiplication in the two taxa are also examined.

scholarly journals DualSeqDB: the host–pathogen dual RNA sequencing database for infection processes

2020 ◽  
Vol 49 (D1) ◽  
pp. D687-D693
Author(s):  
Javier Macho Rendón ◽  
Benjamin Lang ◽  
Marc Ramos Llorens ◽  
Gian Gaetano Tartaglia ◽  
Marc Torrent Burgas
Keyword(s):  
Pathogenic Bacteria ◽  
High Throughput Sequencing ◽  
Homo Sapiens ◽  
Cell Types ◽  
Natural Hosts ◽  
Host Infection ◽  
Infection Processes ◽  
Different Strains

Abstract Despite antibiotic resistance being a matter of growing concern worldwide, the bacterial mechanisms of pathogenesis remain underexplored, restraining our ability to develop new antimicrobials. The rise of high-throughput sequencing technology has made available a massive amount of transcriptomic data that could help elucidate the mechanisms underlying bacterial infection. Here, we introduce the DualSeqDB database, a resource that helps the identification of gene transcriptional changes in both pathogenic bacteria and their natural hosts upon infection. DualSeqDB comprises nearly 300 000 entries from eight different studies, with information on bacterial and host differential gene expression under in vivo and in vitro conditions. Expression data values were calculated entirely from raw data and analyzed through a standardized pipeline to ensure consistency between different studies. It includes information on seven different strains of pathogenic bacteria and a variety of cell types and tissues in Homo sapiens, Mus musculus and Macaca fascicularis at different time points. We envisage that DualSeqDB can help the research community in the systematic characterization of genes involved in host infection and help the development and tailoring of new molecules against infectious diseases. DualSeqDB is freely available at http://www.tartaglialab.com/dualseq.

scholarly journals Expression of multiple isozymes of granulocyte, monocyte, and macrophage esterases in polycythemic Friend erythroleukemia cells

Blood ◽  
1983 ◽  
Vol 62 (2) ◽  
pp. 425-432 ◽  
Author(s):  
JM Woytowicz ◽  
PR Daoust ◽  
J Andre-Schwartz ◽  
SB Levy
Keyword(s):  
Esterase Activity ◽  
Light And Electron Microscopy ◽  
Cell Types ◽  
Morphological Evidence ◽  
Adherent Cell ◽  
Nonspecific Esterase ◽  
Ultrastructural Studies ◽  
Virus Complex ◽  
Erythroleukemic Cell ◽  
Erythroleukemic Cells

Abstract We examined the expression of cytochemical markers of myeloid and monocyte-macrophage differentiation in conjunction with ultrastructural studies of different malignant erythroleukemic cells isolated from mice infected with the Friend polycythemic virus complex (FLV-P). The amounts of fluoride-sensitive and resistant nonspecific esterase activity increased with the progression of malignancy. Isoelectric focusing resolved this enzyme activity into 13 isozymes in the most malignant Friend cell type tested. These same isozymes were found in the adherent cell population of normal spleens. Two of these isozymes were shown to have chloroacetate esterase activity characteristic of granulocytes. Despite these myeloid and monocyte characteristics, light and electron microscopy showed no morphological evidence of differentiation in either of these lineages. This study demonstrates that the Friend erythroleukemic cell contains markers of three different hemopoietic cell types. The expression of myeloid, monocytic, and erythroid traits in these erythroleukemic cells can be used to monitor their malignant progression.

Life cycles of species of Proteocephalus, parasites of fishes in the Palearctic Region: a review

1999 ◽  
Vol 73 (1) ◽  
pp. 1-19 ◽  
Author(s):  
T. Scholz
Keyword(s):  
Intermediate Host ◽  
Body Cavity ◽  
Life Cycles ◽  
The Body ◽  
Individual Species ◽  
Intermediate Hosts ◽  
Palearctic Region ◽  
Second Intermediate Host ◽  
Planktonic Crustaceans ◽  
Fish Hosts

The life cycles of species of Proteocephalus Weinland, 1858 (Cestoda: Proteocephalidea) parasitizing fishes in the Palearctic Region are reviewed on the basis of literary data and personal experimental observations, with special attention being paid to the development within the intermediate and definitive hosts. Planktonic crustaceans, diaptomid or cyclopid copepods (Copepoda), serve as the only intermediate hosts of all Proteocephalus species considered. A metacestode, or procercoid, develops in the body cavity of these planktonic crustaceans and the definitive host, a fish, becomes infected directly after consuming them. No previous reports of the parenteral location of metacestodes within the second intermediate host as it is in the Nearctic species P. ambloplitis have been recorded. Thus, the life cycles of Proteocephalus tapeworms resemble in their general patterns those of some pseudophyllidean cestodes such as Eubothrium or Bothriocephalus, differing from the latter in the presence of a floating eggs instead of possessing an operculate egg from which a ciliated, freely swimming larva, a coracidium, is liberated. The scolex of Proteocephalus is already formed at the stage of the procercoid within the copepod intermediate host; in this feature, proteocephalideans resemble caryophyllidean rather than pseudophyllidean cestodes. The morphology of procercoids of individual species is described with respect to the possibility of their differentiation and data on the spectrum of intermediate hosts are summarized. Procercoids of most taxa have a cercomer, which does not contain embryonic hooks in contrast to most pseudophyllidean cestodes. The role of invertebrates (alder-fly larvae — Megaloptera) and small prey fishes feeding upon plankton in the transmission of Proteocephalus tapeworms still remains unclear but these hosts are likely to occur in the life cycle. Data on the establishment of procercoids in definitive hosts, morphogenesis of tapeworms within fish hosts, and the length of the prepatent period are still scarce and new observations are needed. Whereas extensive information exists on the development of P. longicollis (syns. P. exiguus and P. neglectus), almost no data are available on the ontogeny of other taxa, in particular those occurring in brackish waters (P. gobiorum, P. tetrastomus). The morphology of P. cernuae and P. osculatus procercoids from experimentally infected intermediate hosts is described for the first time.

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