Z Swiderski

Molecular phylogenetic analysis of the Microphalloidea Ward, 1901 (Trematoda: Digenea)

Phylogenetic interrelationships of 32 species belonging to 18 genera and four families of the superfamily Microphalloidea were studied using partial sequences of nuclear lsrDNA analysed by Bayesian inference and maximum parsimony. The resulting trees were well resolved at most nodes and demonstrated that the Microphalloidea, as represented by the present data-set, consists of three main clades corresponding to the families Lecithodendriidae, Microphallidae and Pleurogenidae + Prosthogonimidae. Interrelationships of taxa within each clade are considered; as a result of analysis of molecular and morphological data, Floridatrema Kinsella & Deblock, 1994 is synonymised with Maritrema Nicoll, 1907, Candidotrema Dollfus, 1951 with Pleurogenes Looss, 1896, and Schistogonimus Lühe, 1909 with Prosthogonimus Lühe, 1899. The taxonomic value of some morphological features, used traditionally for the differentiation of genera within the Lecithodendriidae and Prosthogonimidae, is reconsidered. Previous systematic schemes are discussed from the viewpoint of present results, and perspectives of future studies are outlined.

Intraspecific variability among NADH dehydrogenase subunit 1 sequences of Taenia hydatigena

This paper describes intraspecific variability of the partial sequences of the mitochondrial ND1 gene among isolates of Taenia hydatigena from pigs in Poland, Ukraine and Wales. The differences between studied isolates ranged from 0.4 to 5.5%, which exceeds the variability within the same fragment between the different genetic variants of Echinococcus multilocularis and is comparable with the variability between the most closely related strains (G5/G6/G7) of E. granulosus. The biggest difference (5.5%) was found between the geographically most distant Ukrainian and Welsh samples of T. hydatigena while the samples collected from the neighbouring locations in Poland, were most similar to each other.

Differentiation and ultrastructure of the paruterine organs and paruterine capsules, in the nematotaeniid cestode Nematotaenia dispar (Goeze, 1782) Lühe, 1910, a parasite of amphibians

Three types of egg-protecting envelopes of parenchymatic, uterine and embryonic origin have been distinguished in the cyclophyllidean cestode Nematotaenia dispar (Goeze, 1782) Lühe, 1910, a type species for the genus Nematotaenia and the family Nematotaeniidae. The present paper deals with the parenchymatic envelopes, which originate from the modified medullary parenchyma and are represented in this species by the paruterine organs and paruterine capsules. In pregravid proglottids they are composed of clongated myocytons, myofibrils and membranous anucleate cellular processes, containing a large amount of lipid droplets and some calcareous corpuscle cells. These cellular elements (CE) are separated from each other by abundant extracellular matrix (ECM), which consists primarily of an electron lucent ground substance with fine filaments embedded in it. The paruterine capsules of gravid proglottids are surrounded from the outside by a typical medullary parenchyma and are lined by a layer of the connective tissue. The paruterine organs and paruterine capsules show similar ultrastructure. During their histogenesis, all cellular elements undergo extensive flattening, followed by cellular deterioration, with simultaneous reduction in CE/ECM ratio. In the late gravid segments, paruterine capsule walls are very thick and consist of membranous sheets with large amounts of lipid droplets, which cause the cytoplasmic sheets to bulge. Ultrastructure of various types of parenchymatic envelopes in representatives of different cyclophyllidean families, such as paruterine organs in Nematotaeniidae and Mesocestoididae, uterine and parenchymatic egg capsules in Anoplocephalidae (Linstowiinae and Inermicapsiferinae, respectively), is compared.

Systematic position and phylogenetic relationships of the family Omphalometridae (Digenea, Plagiorchiida) inferred from partial lsrDNA sequences

The phylogenetic relationships and systematic position of the digenean genus Omphalometra Looss, 1899 and several other closely related genera, have always been controversial and opinions of different authors on the systematic rank and content of this group have varied greatly. Molecular analysis based on the partial sequences of the large subunit ribosomal DNA gene of representatives of the genera Omphalometra, Rubenstrema and Neoglyphe as well as previously published sequences of members of five families of Plagiorchioidea, has demonstrated: (1) close phylogenetic relationships between these three genera, and (2) a strong support of their position within the family Plagiorchiidae as a well-defined separate clade considered here as a subfamily Omphalometrinae. Molecular data do not support the close affinities of the members of Omphalometrinae and genus Opisthioglyphe as has been suggested by majority of previous authors. Among Omphalometrinae, Omphalometra flexuosa (a parasite of moles, Talpidae) occupies a basal position in relation to Rubenstrema exasperatum and Neoglyphe locellus (both parasitic in shrews, members of the more evolutionary advanced family Soricidae). An extremely low level of lsrDNA sequence divergence between Neoglyphe and Rubenstrema suggests very close phylogenetic relationships of these two genera. Results of the molecular analysis are briefly discussed in comparison with the previously published systems.

Ultrastructure of oncospheral hook formation in the nematotaeniid cestode, Nematotaenia dispar (Goeze, 1782)

Ultrastructural characteristics of oncospheral hook morphogenesis in the nematotaeniid cestode, Nematotaenia dispar, are described. The primordia of embryonic hooks appear in the advanced phase of the pre-oncosphere in 6 specialised hook-forming cells or oncoblasts. Each hook primordium, situated near an invaginated part of the nucleus, is surrounded by numerous free ribosomes, mitochondria and extended Golgi regions. Simultaneously with the hook primordium elongation and transformation into a blade, handle and base, the hook material differentiates into an electron-dense cortex and a less dense, inner, crystal-like core. The exit of the blade of the mature hook, protruding from the oncosphere, is surrounded by a circular, septate desmosome and 2 rigid, dense rings on either side. The pattern of oncospheral hook morphogenesis in N. dispar is compared with that of 2 previously examined cyclophyllidean cestodes, Inermicapsifer madagascariensis and Catenotaenia pusilla.

Ultrastructural study of vitellogenesis and oogenesis of Metadena depressa (Stossich, 1883) Linton, 1910 (Digenea, Cryptogonimidae), intestinal parasite of Dentex dentex (Pisces, Teleostei).

The ultrastructural organization of the female reproductive system of Metadena depressa, digenean intestinal parasite of Sparidae (Dentex dentex), was investigated by electron microscopy. The vitellogenesis is divided into four stages: stage I, vitellocytes have a cytoplasm mainly filled with ribosomes and few mitochondria; stage II, beginning of the synthetic activity; stage III, active shell globule clusters synthesis; stage IV, mature vitellocytes are filled with shell globule clusters and generally contain several large lipid droplets. Glycogen granules are grouped at the periphery of the cell. The three stages of the oogenesis process take place in the ovary: stage I, oogonia are undifferentiated small cells located at the periphery of the organ; stage II, primary oocytes possess a higher nucleo-cytoplasmic ratio and a nucleus with a nucleolus and synaptonemal complexes indicating the zygotene-pachytene stage of the first meiotic division; stage III, mature oocytes are located in the proximal region of the organ and possess a cytoplasmic chromatoid body and cortical granules in a monolayer close to the periphery of the cell.