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At least 19 recordsLinked to original sources

PubMedDate not supplied

[Structure of the epithelium of the parasitic turbellaria Notenera ivanovi (Turbellaria: Fecampiida)].

The ultrastructure of the epithelium in Notentera ivanovi (Turbellaria, Fecampiida) has been studied. Notentera ivanovi lacks the digestive system but has a pad of the epidermal cells on the dorsal side of the body, which seems to be similar to the digestive epidermis on LM. Both the ventral and dorsal epithelium are cellular, ciliated and not insunk (fig. 1, a). The ultrastructure of the ventral and dorsal epithelium is similar in essential features. The cells bear abundant microvilli, cilia and are very rich in mitochondria, but the cytoplasm does not contain lysosomes and shows no other indications of phago- or pinocytosis. The basal membrane of epithelial cells forms deep invaginations (fig. 1, [symbol: see text]), partly with dilations (fig. 1, a; 2, a) containing the lamellated material (3, [symbol: see text]). In the basal part of the cells the numerous Golgi apparatus and rare cysternae of the smooth endoplasmic reticulum were observed (fig. 2, a, [symbol: see text]). The epithelium consists of several types of cells, which differ in the structure of secretory granules. The most abundant type of cells contains the granules with the rough-fibrillated content (fig. 1, a; 2, [symbol: see text]; 3, a). The cells of this type cover most part of the body. In some cells the content of such granules becomes condensed and electron-dense granules appear (fig. 3, a, [symbol: see text]). Another type of cells contains the giant granules with the rough-fibrillated content (fig. 3, [symbol: see text]). Third type of the secret is the granules with the finely fibrillated content which is ejected by exocytosis. The cells of the second and third types form a separate areas of the epithelium of the dorsal side of the body but occasionally were observed in the ventral epithelium too. The epithelium of N. ivanovi differs from that in Kronborgia by the abundance and diversity of secretory contents. The role of the epithelium in the digestion remains conjectural. It seems to be mainly the suckering tissue transporting the low molecular nutrients.

Animals↗

PubMedDate not supplied

[Turbellaria in the lagoon of Ghar-el-Melh. Research on the regenerative ability of Monocelis fusca Oersted (Turbellaria, Monocelididae)].

The Turbellarian Monocelis fusca Oersted is abundant in the lagoon of Ghar-el-Melh. Traumatic regeneration in this animal is realised for the first time. Transversal sections through two levels of the body are made, and pointed out the presence or the absence of regeneration ability with the considered fragment.

Animals↗

PubMed1997

Nutritional and respiratory pathways to parasitism exemplified in the Turbellaria.

Symbiosis is a dominant trait in the Platyhelminthes. The Neodermata (Aspidogastrea, Monogenea, Digenea, Udonellidea, Cestoda) are wholly parasitic and even the predominantly free-living Turbellaria have almost 200 species from 35 families living in permanent associations with other animals. In the simplest turbellarian symbioses, ectosymbiotes such as the Temnocephalida, some other Rhabdocoela and a few Tricladida live on the body surfaces or in the branchial chambers of their mainly arthropodan or chelonian hosts. They feed on the same types of prey as their free-living relatives but supplement their diet by opportunistic commensalism. Their digestive physiology and food reserves are the same as in free-living species. The entosymbiotic Umagillidae, Graffillidae, Pterastericolidae, Fecamplidae and Acholadidae live in internal body cavities or body wall derivatives of echinoderms, molluscs or arthropods and show increasing metabolic dependence on their hosts. Patterns of digestive physiology and food storage generally differ markedly from those of ectosymbiotic and free-living species. Some umagillids, in echinoids, feed as entozoic predators on co-symbiotic protozoa, supplemented by opportunistic ingestion of the hosts' ingesta, gut cells or coelomocytes. Others, in holothurians, feed mainly on gut cells, which also provide some digestive enzymes, and to a lesser extent on host ingesta and co-symbiotes. Graffillids, in molluscs, lack endogenous digestive enzymes and rely entirely on those taken in with host ingesta and gut tissues. Pterastericolids, in asteroids, similarly utilise gut tissues both as food and enzyme sources. The climax to metabolic dependence occurs in the Fecamplidae and Acholadidae. The former, in crustacean haemocoels and myzostomid tissues, lack conventional alimentary systems and absorb soluble nutrients through the epidermis. In the latter the only known species lives in the tube feet of its asteroid host, lacks a normal endodermal gut, but has a modified epidermis performing both digestive and absorptive functions. Most of these entosymbiotes show a shift from the lipid storage characteristic of free-living and ectosymbiotic species to the glycogen storage predominating in the Neodermata. In both groups this emphasis on carbohydrate metabolism is often independent of the PO2 of their environment. Both groups also show high fecundity and it is suggested that there is a direct relationship between this and glycogen storage. High fecundity, while clearly of adaptive value in entosymbiotes, is arguably primarily related to the assured food supply conferred by the entosymbiotic habit and thus can be viewed as a consequence of the latter rather than a prerequisite for it. Some entosymbiotic Turbellaria have evolved physiologically active haemoglobins, allowing them to abstract oxygen preferentially from host tissues; some have also evolved facultative glycolytic mechanisms comparable to those of the Cestoda. All these adaptations to ecto- and entosymbiotic life in the Turbellaria exemplify possible pathways to wholly parasitic lifestyles, with total metabolic dependence on the hosts, which may have been followed during the evolution of the Neodermata.

Animal Nutritional Physiological Phenomena↗

PubMed1975

Uniflagellate spermatozoa in Nemertoderma (Turbellaria) and their phylogenetic significance.

An ultrastructural study of Nemertoderma (Turbellaria, Nemertodermatida) has revealed that its spermatozoa have only a single falgellum. This is the first uniflagellate spermatozoon known in the Turbellaria; it is indicative of the primitiveness of Nemertoderma and is evidence in support of the view that the Turbellaria as a whole are among the most primitive living Bilateria.

Acrosome↗

PubMed1978

Paddle cilia and discocilia - genuine structures? Observations on cilia of sensory cells in marine turbellaria.

Kinocilia of epidermal sensory cells in fixed marine Turbellaria often terminate as flattened biconcave discs. The distal part of the ciliary axoneme curves back upon itself forming a 360 degree loop which is enveloped by the plasmalemma. In living animals this structure can be induced by the addition of sodium cacodylate, monobasic sodium phosphate, dibasic sodium phosphate, sucrose, calcium chloride, or formaldehyde to the sea water. Specimens treated with sodium chloride, glutaraldehyde, or osmium tetroxide do not show modified cilia. In animals prepared for EM at low temperature and with a buffered hypotonic fixative less kinocilia are modified than in animals treated with a buffered iso- or hypertonic fixative and at a higher temperature. It is assumed that the unusually shaped cilia, described as "paddle cilia" or "discocilia" in other invertebrates, do not represent a genuine but an artificial structure.

Animals↗

PubMed1980

Ultrastructure of epidermal eyespots of Microstomum lineare (Turbellaria, Macrostomida).

The eyespots of Microstomum lineare were studied by electron microscopy, light microscopy, and fluorescence microscopy. Each eyespot consists of two ciliary photoreceptor cells shielded by pigment cells and additional sensory cells. The photoreceptor cells are characterized by a distal intracellular cavity lined with 50-100 interwoven cilia. The other sensory cells are of two ultrastructurally different types, one with long cilia predominating and the other with balloonlike cilia. The pigment cells, which envelop processes of the sensory cells, contain pigment vacuoles varying in size and content and give a bright red fluorescence by the Falck-Hillarp method. The eyespots are suggested to perform a dual function as photoreceptors and chemoreceptors. The evolutionary significance of ciliary photoreceptors in Turbellaria is discussed.

Animals↗

PubMed1980

The nervous system of Microstromum lineare (Turbellaria, Macrostomida). I. A fluorescence and electron microscopic study.

The nervous system (NS) of Microstomum lineare (Turbellaria, Macrostomida) was studied by electron and light microscopy, combined with fluorescence histochemistry (Falck-Hillarp method for biogenic monoamines). The NS is primitively organized, with a bilobed brain, two lateral nerve cords lacking commissures, and peripheral nerve cells scattered along the nerve cords. The stomatogastric NS, with a pharyngeal nerve ring, is joined to the central NS by a pair of connective ganglia. A green fluorescence in all parts of the NS indicates catecholaminergic neurons as the dominant neuron type. Ultrastructurally, two types of neurons were identified on the basis of their vesicle content: 1. Aminergic (catecholaminergic) neurons containing dense-core vesicles of varying electron-density and size, i.e., small dense-core vesicles (diameter 50--100 nm), vesicles with a highly electron-dense core (60--140 nm), and vesicles with an eccentric dense-core. 2. Presumed peptidergic neurosecretory neurons containing large granular vesicles (diameter about 200 nm) in the stomatogastric NS and peripheral parts of the central NS. In light microscopy, paraldehyde-thionin stained neurons were observed in the same areas.

Animals↗

PubMed1996

Evidence that two types of 18S rDNA coexist in the genome of Dugesia (Schmidtea) mediterranea (Platyhelminthes, Turbellaria, Tricladida).

Sequences of 18S ribosomal DNA (rDNA) are increasingly being used to infer phylogenetic relationships among living taxa. Although the 18S rDNA belongs to a multigene family, all its copies are kept homogeneous by concerted evolution (Dover 1982; Hillis and Dixon 1991). To date, there is only one well-characterized exception to this rule, the protozoan Plasmodium (Gunderson et al. 1987; Waters, Syin, and McCutchan 1989; Qari et al. 1994). Here we report the 1st case of 18S rDNA polymorphism within a metazoan species. Two types (I and II) of 18S rDNA have been found and sequenced in the platyhelminth Dugesia (Schmidtea) mediterranea (Turbellaria, Seriata, Tricladida). Southern blot analysis suggested that both types of rDNA are present in the genome of this flatworm. This was confirmed through sequence comparisons and phylogenetic analysis using the neighbor-joining method and bootstrap test. Although secondary structure analysis suggests that both types are functional, only type I seems to be transcribed to RNA, as demonstrated by Northern blot analysis. The finding of different types of 18S rDNAs in a single genome stresses the need for analyzing a large number of clones whenever 18S sequences obtained by PCR amplification and cloning are being used in phylogenetic reconstruction.

Animals↗

PubMed1998

Prevalence of Mytilicola intestinalis (Copepoda: Mytilicolidae) and Urastoma cyprinae (Turbellaria: Hypotrichinidae) in marketable mussels Mytilus galloprovincialis in Italy.

Marketable mussels Mytilus galloprovincialis traded with commercial certification from production sites in Italy and abroad (France, Spain) were examined for the presence of Mytilicola intestinalis (Copepoda: Mytilicolidae) and Urastoma cyprinae (Turbellaria: Hypotrichinidae) from October 1994 to February 1996. The prevalence of M. intestinalis was 4.1% and 4.7% respectively in mussels from Lerici (La Spezia) and S. Pietro in Volta (Venice), whereas it rose to 57.9% in the samples from Spain. M. intestinalis was absent in mussels from Chioggia (Venice), Ganzirri (Messina), Taranto, Trieste and France. The prevalence of U. cyprinae varied considerably, ranging from 0.3% in mussels from Trani (Bari) to 33.2% and 86.3% respectively in those from Chioggia and Trieste. It was 85.7% in samples from France and 63.7% in those from Spain.

Animals↗

PubMed1980

[Turbellaria in the gulf of Tunis. I. Morphology].

This is a preliminary work for a regeneration study which experimental results will be published posteriorly. This first note describes three triclads Turbellaria found in the gulf of Tunis for the first time: Procerodes lobata O. Schmidt, 1862, Procerodes dohrni Wilhelmi, 1909 and Sabussowia dioica Claparède, 1863. Precisions concerning ecological preferences and geographical distribution have been given.

Animals↗

PubMedDate not supplied

[Acid phosphatase activity during digestion in the anintestinal turbellaria Convoluta convoluta].

Studies have been made on changes in the activity of acid phosphatase during the digestion in the turbellaria C. convoluta. The increase of the enzymic activity of cytoplasm of the peripheral parenchyma at the initial stages after feeding (6 hours, 1 day) and gradual decrease of this activity at later stages (2,4 and 7 days) were noted. The presence of acid phosphatase in the nuclei and cytoplasm of cells of the central parenchyma at all stages of the digestive cycle is explained by degeneration of these cells which is associated with holocrine secretion of the digestive enzymes.

Acid Phosphatase↗

PubMed1993

Optimizing a method of protein extraction for two-dimensional electrophoretic separation of proteins from planarians (Platyhelminthes, Turbellaria).

Different procedures for microscale extraction of proteins from small amounts of tissue of planarians (Platyhelminthes, Turbellaria) to be analyzed by two-dimensional gel electrophoresis (2-D PAGE) are compared. Three extraction methods were assessed: (i) extraction of soluble proteins with nondenaturing Tris buffers, (ii) extraction with Tris buffer containing the anionic detergent sodium dodecyl sulfate (SDS), and (iii) denaturing extraction under reducing conditions in the presence of urea and Nonidet P-40 (NP-40) with or without SDS. Buffers combining minute concentrations of SDS (0.01%), denaturing concentrations of urea (8M) and alkaline pH solubilized the greatest number of proteins without detectable proteolysis. Neither the presence of protease inhibitors nor higher concentrations of SDS improved protein extraction. We have applied this method to planarians to detect proteins specific to the pharynx. The resulting two-dimensional pattern shows a larger number of specific spots than in previous extraction methods.

Animals↗

PubMed1965