[Show abstract][Hide abstract] ABSTRACT: Spermiogenesis and ultrastructure of mature spermatozoon of the caryophyllidean cestode Hunterella nodulosa, a parasite of suckers (Catostomidae), have been studied by transmission electron microscopy. This monozoic tapeworm is unique in its mode of attachment and represents the second North American species studied. The process of spermiogenesis of H. nodulosa follows the general pattern already described in other caryophyllideans. The most characteristic feature is the presence of a slight rotation of the flagellar bud, which seems to be a typical character of spermiogenesis in this cestode group. The mature spermatozoon of H. nodulosa is characterized by the presence of one axoneme of 9 + "1" type of the trepaxonematan flatworms surrounded by a semi-arc of cortical microtubules in its anterior extremity, parallel nucleus and cortical microtubules arranged in a parallel pattern, which corresponds to the Type III pattern of cestode spermatozoa according to Levron et al. (2010). Comparison of the present data with those available for other caryophyllideans did not reveal substantial differences, even though they belong to different families, infect different hosts (catostomid, cyprinid and siluriform fishes) and occur in distant zoogeographical regions. This indicates uniformity of the process of sperm formation and spermatozoon ultrastructure in one of the evolutionarily most ancient groups of tapeworms.
[Show abstract][Hide abstract] ABSTRACT: Tapeworms (Cestoda, Platyhelminthes) are a highly diversified group of parasites that can have significant veterinary importance as well as medical impact as disease agents of human alveococcosis, hydatidosis, taeniosis/cysticercosis/neurocysticercosis, hymenolepidosis or diphyllobothriasis. Because of their great diversity, there has been keen interest in their phylogenetic relationships to other obligate parasitic platyhelminthes, as well as within the group itself. Recent phylogenetic analyses of cestodes, however, have focused on morphological, molecular, life cycle, embryology and host-specificity features and conspicuously omitted inclusion of karyological data. Here we review the literature from 1907 to 2010 and the current status of knowledge of the chromosomes and cytogenetics within all of the cestode orders and place it within an evolutionary perspective. Karyological data are discussed and tabulated for 115 species from nine eucestode orders with ideograms of 46 species, and a comparison of cytogenetic patterns between acetabulate and bothriate cestode lineages is made. Attention is drawn to gaps in our knowledge for seven remaining orders and cestodarian groups Gyrocotylidea and Amphilinidea. Among the cytogenetic aspects covered are: chromosome number, triploidy, classical karyotype cytogenetics (banding patterns, karyotype asymmetry, secondary constrictions), as well as advanced karyotype techniques allowing location of genes on chromosomes by fluorescence in situ hybridization. We demonstrate that further progress in cestode karyosystematics rests with new molecular approaches and the application of advanced cytogenetic markers facilitating intimate karyotype analysis.
Full-text · Article · Dec 2011 · Advances in Parasitology
[Show abstract][Hide abstract] ABSTRACT: Chromosomes of the invasive tapeworm Khawia sinensis (Caryophyllidea), the specific parasite of common carp, were analyzed by means of conventional Giemsa staining and using fluorescent DAPI and YOYO-1 dyes, silver staining, and fluorescent in situ hybridization (FISH) with 18S rDNA probe. The karyotype is composed of eight pairs of metacentric and telocentric chromosomes (2n = 16, n = 3m + 5t, TCL = 42.54 μm). Constitutive heterochromatin was located at pericentromeric regions of all pairs, except for the largest metacentric pair (no. 1), which possessed no DAPI-positive band. FISH with rDNA probe revealed that both homologues of chromosome pair no. 6 carry a cluster of ribosomal arrays, which were located interstitially close to the centromere. Present results are compared with previous cytogenetic data on Khawia spp., and comments are made on the karyotypes with respect to their phylogenetic links.
Full-text · Article · Dec 2011 · Parasitology Research
[Show abstract][Hide abstract] ABSTRACT: Chromosomal characteristics, i.e., number, size, morphology, and location of ribosomal DNA (rDNA) clusters were examined in
two medically important liver flukes, Fasciola hepatica and Fascioloides magna (Fasciolidae), using conventional Giemsa staining and fluorescent in situ hybridization (FISH) with ribosomal 18S rDNA probe.
A comparison of F. magna and F. hepatica karyotypes confirmed significant differences in all chromosomal features. Whilst the karyotype of F. hepatica comprised ten pairs of chromosomes (one metacentric and nine medium-sized subtelocentrics and submetacentrics; 2n = 20, n = 1 m + 5 sm + 4 st; TCL = 49.9μm), the complement of F. magna was composed of 11 pairs of medium-sized subtelocentrics and submeta-metacentrics (2n = 22, n = 9 st + 1 sm + 1 sm-m; TCL = 35.2μm). Noticeable differences were found mainly in length and morphology of first chromosome
pair. It was metacentric and 9.0μm long in F. hepatica while subtelocentric and 4.7μm long in F. magna. Although FISH with rDNA probe revealed a single cluster of ribosomal genes in both species, conspicuous interspecific differences
were displayed by chromosomal location of ribosomal loci (i.e., NORs). The signals were found on short arms of fifth homologous
pair in F. hepatica; however, they were detected in pericentromeric regions of the long arms of tenth pair in F. magna. The observed cytogenetic differences were interpreted in terms of karyotype evolution of fasciolid flukes; F. hepatica may be regarded phylogenetically younger than F. magna. The present paper provides a pilot study on molecular cytogenetics within a group of hermaphroditic digenetic flukes.
Full-text · Article · Oct 2011 · Parasitology Research
[Show abstract][Hide abstract] ABSTRACT: Atractolytocestus huronensis Anthony, 1958 (Caryophyllidea) is a monozoic (non-segmented) tapeworm, parasitising exclusively carp (Cyprinus carpio L.) and recently rapidly spreading in Europe. It was originally described in the Huron River, Michigan, USA and reported only from North America until the late 1990s, but its origin is not exactly clear yet. In Europe, A. huronensis was first found in England in 1993 and in last decade it was detected in several European countries, such as Hungary, Slovakia, Czech Republic, Germany, Croatia and Romania. The molecular study focused on determination of interrelationships among European populations of parasite imply that introduction of A. huronensis to Europe was probably a result of two independent events directed to England and Continental Europe. The chapter provides an overview of taxonomy, morphology (including ultrastructure), life cycle, geographic distribution, pathogenicity, treatment and veterinary importance of this parasite. Besides general biological traits and specific properties typical for invasive species, such as particular adaptation abilities, successful colonization of new regions and pathogenic potential, A. huronensis also excels in several peculiar molecular and genetic features studied in detail in Slovak population of the parasite. Sequential analysis of ribosomal internal transcribed spacers 1 and 2 (ITS1, ITS2 rDNA) revealed divergent intragenomic ITS copies which were mostly induced by the nucleotide substitutions and different numbers of short repetitive motifs within the sequence. The karyotype possesses three sets of chromosomes (3n = 24, n = 4m + 3st + 1 minute chromosome). Fluorescent in situ hybridization (FISH) with 18S rDNA probe revealed two distinct rDNA clusters for each homologue of the chromosome triplet number 2. Atractolytocestus huronensis is so far the only tapeworm species in which intra-individual ITS sequence variants were found to be linked in parallel with its triploid nature and multiple rDNA loci. Triploid organisms are supposed to reproduce by parthenogenetic mode. Ultrastructural observations of spermiogenesis and vitellogenesis revealed several features that indicate asexual (parthenogenetic) reproduction of A. huronensis. The most prominent character of spermatocytes of this species is fragmentation of nuclei, a clear feature of cell degeneration. Although parthenogenesis has no substantial consequence for vitellogenesis, differences were found with respect to the ultrastructure of the interstitial tissue, shell globule clusters, and the presence/absence of the "lamellar" granules.
[Show abstract][Hide abstract] ABSTRACT: The effect of the fungicide Euparen Multi (containing 50% tolylfluanid) was investigated on the induction of chromosomal aberrations (CA) in cultured bovine peripheral lymphocytes. Cultures from two healthy donors were treated with tolylfluanid-based fungicide at concentrations ranging from 1.7 to 17.5 μg/ml for the last 24 and 48 hours of cultivation. Conventional cytogenetic method (CA assay) with Giemsa staining as well as fluorescence in situ hybridization (FISH) with whole bovine chromosomes 1 and 5 painting probes were used in the experiment. In the CA assay, no clastogenic effect of the fungicide was found after Euparen Multi treatment for 24 hours. On the contrary, significant elevation in polyploidy induction was observed with dose-dependence in one of the donors. Using prolonged time of exposure to the fungicide (the last 48 h of the cultivation), a slight clastogenic effect was detected at the doses of 8.75 and 17.5 μg/ml (P < 0.05, P < 0.01, respectively) in donor 1 and at the dose of 8.75 μg/ml (P < 0.05) in donor 2. The highest doses tested caused reduction of the mitotic indices (MI) (P < 0.05, P < 0.01) in both donors as well as both treatment times. The evaluation of stable structural aberrations in lymphocytes by two-colour FISH (48 h exposure) using bovine chromosome painting probes revealed the presence of nonreciprocal translocations at two examined concentrations (3.5 μg/ml and 8.75 μg/ml).
Full-text · Article · Dec 2010 · Acta Biologica Hungarica
[Show abstract][Hide abstract] ABSTRACT: Spermiogenesis and spermatozoon ultrastructure of the caryophyllidean cestode Breviscolex orientalis Kulakovskaya, 1962, first member of the family Capingentidae studied, a parasite of cyprinid fish Abbottina rivularis, are described using transmission electron microscopy. Spermiogenesis in B. orientalis follows the Type II pattern described by Bâ and Marchand (Mém Mus Natl Hist Nat 166:87-95, 1995) for cestodes. It begins with the formation of a zone of differentiation containing a large nucleus and a pair of centrioles. The centrioles are separated from one another by an intercentriolar body composed of three electron-dense layers. Each centriole is associated with typical striated roots. At the beginning of the spermiogenesis, an electron-dense material is observed in the apical region of the differentiation zone. During the initial stage of spermiogenesis, one of the centrioles gives rise to a free flagellum, which then rotates and undergoes proximodistal fusion with the cytoplasmic protrusion of the differentiation zone. The mature spermatozoon of B. orientalis corresponds to the Type III pattern described by Levron et al. (Biol Rev 85:523-543, 2010). It is characterized by the absence of mitochondrion and crested body. Five regions of the mature spermatozoon are differentiated. The main ultrastructural characteristics are: one axoneme of 9+ "1" trepaxonematan pattern, cortical microtubules and nucleus. The comparison of the spermiogenesis of B. orientalis with those of the other caryophyllidean species demonstrates some variation within the order relative to the presence and morphology of the intercentriolar body, the presence of slight rotation of the flagellar bud and a complete proximodistal fusion of the free flagellum with a cytoplasmic protrusion.
Full-text · Article · Nov 2010 · Parasitology Research
[Show abstract][Hide abstract] ABSTRACT: The study describes a karyotype of a common parasite of cervids, the giant liver fluke, Fascioloides magna (Trematoda, Platyhelminthes). The chromosome set of F. magna comprises 11 pairs of chromosomes, all classified as subtelocentric except for the submeta-metacentric pair No. 8 and the
submetacentric pair No. 10 (2n = 22, n = 1sm + 1sm-m + 9st). The first longest pair is 4.65 μm long and the length decreases
continuously to the 1.92 μm length of the last pair No. 11. No distinct secondary constriction has been observed in mitotic
preparations. Fluorescent DAPI-staining reveals distinct heterochromatin bands on all 11 chromosome pairs in the centromeric
regions; another DAPI-positive bands are localized at the end of the long arms of chromosomes No. 5 and the last less distinct
signals appear interstitially on the long arms of the pair No. 6. Synchronous meiotic divisions of 8-spermatocyte groups have
been observed during spermatogenesis, similarly with a development of spermatocytes in other trematodes. In the first two
stages of heterotypic spermatocyte division, 11 bivalents (n = 11) are regularly observed, confirming the diploid number of
22 elements. Furthermore, the present analysis summarises and discusses available cytogenetic data on Fasciolidae flukes suitable
for future studies on taxonomy or phylogenetic interrelationships within the family.
Keywordsfasciolid flukes-chromosome-fluorescent staining-heterochromatin
[Show abstract][Hide abstract] ABSTRACT: Karyotype and chromosomal characteristics, i.e. number and location of ribosomal DNA (rDNA) clusters, and sequence variation of the ribosomal internal transcribed spacer 2 (ITS2) were studied in a monozoic (unsegmented) tapeworm, Caryophyllaeides fennica (Caryophyllidea), using conventional and Ag-staining, fluorescent in situ hybridization (FISH) with 18S rDNA probe, and PCR amplification, cloning and sequencing of the complete ribosomal ITS2 spacer. The karyotype of this species was composed of ten pairs of metacentric (m) chromosomes (2n=20). All chromosomes except the pair No. 2 displayed DAPI-positive heterochromatin in centromeric regions. In addition, two distinct interstitial DAPI-positive bands were identified on chromosome pair No. 7. FISH with 18S rDNA probe revealed four clusters of major ribosomal genes situated in the pericentromeric region of the short arms in two pairs of metacentric chromosomes Nos. 8 and 9. Hybridization signals were stronger in the pair No. 8, indicating a higher amount of rDNA repeats at this nucleolar organizer region (NOR). Analysis of 15 ITS2 rDNA sequences (five recombinant clones from each of three individuals) showed 13 structurally different ribotypes, distinguished by 26 nucleotide substitutions and variable numbers and combinations of short repetitive motifs that allowed sorting the sequences into four ITS2 variants. These results contribute to recently published evidence for the intraindividual ribosomal ITS sequence variability in basal tapeworms with multiple rDNA loci and imply that both phenomena may be mutually linked.
Full-text · Article · May 2010 · Parasitology International
[Show abstract][Hide abstract] ABSTRACT: 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 22.1μm) 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 12.5μm in P. bliccae, 9.2μm in P. sapae, and 9.9μm in P. nagibinae. All four species are similar in their total complement length, ranging from 64.4 to 50.4μm. 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.
No preview · Article · Apr 2010 · Parasitology Research
[Show abstract][Hide abstract] ABSTRACT: This paper reports results of the first cytogenetic study carried out on a recently described monozoic tapeworm, Khawia saurogobii Xi et al., 2009, from the Chinese lizard gudgeon (Saurogobio dabryi). The karyotype of this species is composed of eight pairs of metacentric and telocentric chromosomes (2n = 16; n = 3m + 5t), metacentric chromosomes representing the first, sixth, and eight pairs. All chromosomes except the largest pair displayed 4',6-diamidino-2-phenylidole (DAPI) positive heterochromatin in centromeric regions. In mitotic preparations stained with Giemsa, one of the homologues of a smaller metacentric chromosome pair (No. 7) showed a distinct secondary constriction, whereas the other did not. Fluorescent in situ hybridization (FISH) with 18S ribosomal DNA (rDNA) probe revealed that the chromosomes No. 7 carry each a cluster of ribosomal genes associated with the centromeric heterochromatin and confirmed that this chromosome pair contains a nucleolar organizer region (NOR). The rDNA-FISH also confirmed heteromorphism in the size of NOR (i.e., secondary constriction) observed after Giemsa staining. The present cytogenetic analysis revealed species-specific characters of K. saurogobii and showed that FISH may represent a new valuable cytogenetic tool suitable for comparative taxonomic or phylogenetic studies within the order Caryophyllidea in the future.
Full-text · Article · Feb 2010 · Parasitology Research
[Show abstract][Hide abstract] ABSTRACT: Complete sequences of the ribosomal internal transcribed spacers (ITS1 and ITS2) and karyological characters of the monozoic (unsegmented) tapeworm Atractolytocestus huronensis Anthony, 1958 (Cestoda: Caryophyllidea) from Slovakia were analysed, revealing considerable intra-genomic variability and triploidy in all analysed specimens. Analysis of 20 sequences of each ITS1 and ITS2 spacer yielded eight and 10 different sequence types, respectively. In individual tapeworms, two to four ITS1 and three to four ITS2 sequence types were found. Divergent intra-genomic ITS copies were mostly induced by nucleotide substitutions and different numbers of short repetitive motifs within the sequence. In addition, triploidy was found to be a common feature of A. huronensis. The karyotype of Slovakian A. huronensis possesses three sets of chromosomes (3n=24, n=4m+3st+1minute chromosome), similar to the previously described triploidy in conspecific tapeworms from North America. Fluorescent in situ hybridisation (FISH) with a ssrDNA probe revealed two distinct rDNA clusters for each homologue of the triplet number 2. To date, A. huronensis is the only cestode species in which intra-individual ITS sequence variants were found in parallel with its triploid nature and multiple rDNA loci. Some of these molecular and genetic features were observed in several other species of basal or nearly basal tapeworms of the orders Caryophyllidea and Diphyllobothriidea, which indicates that the phenomena may be characteristic for evolutionarily lower tapeworms and deserve more attention in future studies.
Full-text · Article · Aug 2009 · International journal for parasitology