Caryophyllideans are intestinal parasites of freshwater fishes, occupying a basal position among the ‘true’ tapeworms. We performed detailed cytogenetic analyses of the well-known caryophyllidean species Caryophyllaeus laticeps. For comparison, we also examined for the first time the chromosomes of Paracaryophyllaeus gotoi, a specific parasite of loaches in China. Both species showed a diploid chromosome number of 2n = 20, n = 10m. Chromomycin A3 (CMA3)/diamidino-2-phenylindole (DAPI) staining performed for the first time in the class Cestoda revealed CMA3+/DAPI− bands in the pericentromeric regions of the short arms of chromosome pair no. 7 in the karyotype of C. laticeps. Fluorescence in situ hybridization with the 18S rDNA probe confirmed the presence of a single cluster of major rDNA near the centromere on a pair of small chromosomes in both species. These findings support the hypothesis that the ancestral state in the family Caryophyllaeidae is a single interstitial cluster of major rDNA genes and thus one nucleolar organizer region per haploid genome. Our results, which we presented together with literature data plotted on a phylogenetic tree, show stability of caryophyllidean karyotypes at the genus level, but showed differences between genera without a clear phylogenetic signal. The data allowed us to at least formulate a hypothesis about the ancestral haploid chromosome number of n = 10 for the family Caryophyllaeidae and possibly for the sister family Capingentidae. In addition, we compared two populations of C. laticeps from water bodies with different levels of polychlorinated biphenyl contamination, showing a slightly increased incidence of chromosomal abnormalities at the contaminated site.

• Klíčová slova
• Chromosome aberration, FISH, environmental pollution, karyotype, karyotype evolution, ribosomal DNA,
• MeSH
• Cestoda * genetika   MeSH
• cytogenetické vyšetření MeSH
• fylogeneze MeSH
• hybridizace in situ fluorescenční MeSH
• karyotyp MeSH
• máloostní * MeSH
• paraziti * genetika   MeSH
• ribozomální DNA genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ribozomální DNA MeSH

The large-sized tapeworm Dibothriocephalus latus is known as the broad or fish-borne cestode of mammals that is capable to infect humans and cause diphyllobothriosis. Recently, molecular data on D. latus has been accumulating in the literature and a complete genome sequence has been published; however, little is known about the karyotype and chromosome architecture. In this study, an in-depth karyological analysis of 2 D. latus specimens was carried out. The plerocercoids originated from a perch caught in subalpine Lake Iseo (Italy) and the tapeworms were reared in hamsters. Both specimens contained cells with a highly variable number of chromosomes ranging from18 to 27. Nevertheless, the largest portion of mitotic figures (47%) showed a number corresponding to the triploid set, 3n = 27. Accordingly, the karyotype of the analyzed specimens consisted of 9 triplets of metacentric chromosomes. Fluorescence in situ hybridization (FISH) with the 18S rDNA probe clearly demonstrated the presence of 3 clusters of hybridization signals on the triplet of chromosome 7, thus confirming the triploid status of the specimens. FISH with a telomeric (TTAGGG)n probe confined hybridization signals exclusively to the terminal chromosomal regions, supporting the earlier findings that this repetitive motif is a conserved feature of tapeworm telomeres.

• Klíčová slova
• 18S rDNA, parthenogenesis, polyploidization, telomeres, triploid,
• MeSH
• chromozomy genetika   MeSH
• cytogenetické vyšetření MeSH
• difylobotriáza parazitologie   MeSH
• Diphyllobothrium genetika   metabolismus   MeSH
• hybridizace in situ fluorescenční MeSH
• karyotyp MeSH
• RNA helmintů analýza   MeSH
• RNA ribozomální 18S analýza   MeSH
• triploidie * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• RNA helmintů MeSH
• RNA ribozomální 18S MeSH

An original cytogenetic study combining classical karyotype analysis and modern fluorescence in situ hybridization using telomeric (TTAGGG)n and ribosomal sequences (18S rDNA) was performed in Khawia abbottinae (Cestoda, Caryophyllidea), a parasite of Chinese false gudgeon (Abbottina rivularis) from China. Analyses based on conventional Giemsa staining, DAPI, YOYO-1 dye, and silver (Ag) staining were also carried out. The karyotype is composed of eight pairs of metacentric and telocentric chromosomes (2n = 16, n=5m + 3t). Constitutive heterochromatin was mainly positioned at pericentromeric regions, and telomeric sequences (TTAGGG)n were restricted to the end of all chromosomes. In mitotic preparations stained with Giemsa, both homologues of chromosome pair 4 showed a distinct secondary constriction. FISH with rDNA probe confirmed that this secondary constriction contains a nucleolar organizer region (NOR). The process of spermatocyte meiosis and the dynamics of nucleolus degradation in dividing cell were scrutinized. The present study and its results enhance the limited knowledge on basic karyotype characteristics and 18S rDNA clusters location in caryophyllidean tapeworms.

• Klíčová slova
• 18S rDNA mapping, Cestoda, FISH, Karyotype, Telomeres,
• MeSH
• Cestoda klasifikace   genetika   izolace a purifikace   MeSH
• chromozomy genetika   MeSH
• Cyprinidae genetika   MeSH
• DNA helmintů genetika   MeSH
• heterochromatin genetika   MeSH
• hybridizace in situ fluorescenční MeSH
• karyotyp MeSH
• karyotypizace MeSH
• proteiny červů genetika   MeSH
• ribozomální DNA genetika   MeSH
• ribozomy genetika   MeSH
• telomery genetika   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Čína MeSH
• Názvy látek
• DNA helmintů MeSH
• heterochromatin MeSH
• proteiny červů MeSH
• ribozomální DNA MeSH