Effect of the digenean parasites of fish on the fauna of Mediterranean lagoons.

Attention is drawn to the effects of parasites on their hosts, taking as a model the digenean parasites of teleosts (hereafter: fish) from lagoons along the French Mediterranean coast. Because digeneans have a heteroxenic life cycle, their impact is not limited to the definitive host, which harbours the sexual adults, but is extended to the first host (mollusc) and to the second host ("invertebrate" or fish). Adult parasites, in order to ensure efficient sexual reproduction, never cause excessive damage to their definitive host, usually only exploiting the intestinal fluids; however, the host must intensify its search for prey, which results in a diminished fitness. Within the first host, 'larval' stages of digenean parasites invade the gonads, resulting in its castration, then exhaustion and eventually death. The diversion of energy from the second hosts towards the parasites forces them to intensify their search for food, resulting in decreased fitness and an increased risk of being eaten; in addition, manipulation of the host's behaviour by parasites drives this host into the food chain of the definitive host. In lagoons, many individuals of almost all species of fish and invertebrates act as first, second and/or definitive hosts for digeneans. Obviously, parasites have a severe impact on the population dynamics of key taxa, on the food web and therefore also on the functioning of the whole lagoon ecosystem. Yet this impact has been largely overlooked or underestimated in functioning models, by ecologists, who tend to prioritize more apparent trophic relationships.

Species diversity among the genus Monorchis (Digenea: Monorchiidae) parasitic in marine teleosts: molecular, morphological and morphometrical studies with a description of Monorchis blennii n. sp.

Molecular, morphological and morphometrical studies were conducted on two species of the genus Monorchis (Monorchiidae), Monorchis parvus and Monorchis monorchis, collected in different fish hosts from the Mediterranean Sea. The analysis of internal transcribed spacer 1 sequences of ribosomal DNA showed that M. monorchis specimens from Parablennius gattorugine were strongly divergent (12.9%) from specimens of this species collected in Spondyliosoma cantharus and Diplodus puntazzo. This high genetic variation was confirmed by the analysis of morphological structures and morphometrics, which showed that M. monorchis specimens from P. gattorugine can be distinguished from those of S. cantharus and D. puntazzo by several morphological characteristics, including body size, number and distribution of vitelline follicles, testis shape, structure of the cirrus pouch, and number of eggs. Our results show that M. monorchis specimens isolated from P. gattorugine represent a clearly distinct entity from M. monorchis found in the other hosts, which has enabled us to describe a new species, Monorchis blennii n. sp.

A redescription of Homalometron senegalense Fischthal & Thomas, 1972 (Digenea: Apocreadiidae) from Synaptura kleinii (Teleostei) of the western Mediterranean.

The apocreadiid digenean Homalometron senegalense is redescribed from the soleid fish Synaptura kleinii from off Corsica in the western Mediterranean. For the first time, lymphatic vessels are described for this species, and the implications of this in the systematics of the Apocreadiidae discussed. This species is considered closest to H. galaicus and H. wrightae, both also reported from soleid hosts. The concept of Apocreadiidae espoused is that most recently developed by Cribb & Bray (1999).

Metadena phoceae n. sp. (Digenea: Cryptogonimidae), a rectal parasite of the shore rockling Gaidropsarus mediterraneus (Teleostei: Lotidae) in the western Mediterranean.

Metadena phoceae n. sp. is described and figured in detail from the rectum of the shore rockling Gaidropsarus mediterraneus (Lotidae) in the Gulf of Marseilles and off Corsica. It is compared with other cryptogonimids occurring in Mediterranean and Black Sea fishes and is distinguished from its closest relatives, M. depressa (Stossich, 1883) and M. pauli (Vlassenko, 1931), which occur in sparid and sciaenid fishes, respectively, by both morphometrical and biological features. The host-specificity of cryptogonimids occurring in Mediterranean and Black Sea fishes is commented upon.

Contribution to the knowledge of species of the genus Stephanostomum Looss, 1899 (Digenea: Acanthocolpidae) from teleosts of the Western Mediterranean, with the description of S. gaidropsari n. sp.

Four species of the acanthocolpid genus Stephanostomum are redescribed from the digestive tract of teleosts in the Western Mediterranean: the type-species, S. cesticillum from Lophius piscatorius is described with a ventrally interrupted ring of 35 circum-oral spines and as lacking a uroproct; S. bicoronatum from Sciaena umbra has a ventrally interrupted ring of 31 circum-oral spines and a uroproct; S. pristis from Phycis phycis has an uninterrupted ring of 36 oral spines and no uroproct; S. minutum from Uranoscopus scaber has an uninterrupted ring of 36 oral spines and a uroproct. A new species, S. gaidropsari from Gaidropsarus mediterraneus, is described with an uninterrupted ring of 36 oral spines and an apparent uroproct. It differs from all other Stephanostomum species with similar oral spine numbers in the armament of the ejaculatory duct, and from various of these species by vitelline distribution, length of the genital atrium, oesophageal length and sucker-ratio.

Molecules, morphology and morphometrics of Cainocreadium labracis and Cainocreadium dentecis n. sp. (Digenea: Opecoelidae) parasitic in marine fishes.

Molecular, morphological and morphometric analyses were conducted on several samples of Cainocreadium labracis (Opecoelidae), a trematode parasitic in marine teleosts. The samples were isolated from several specimens of Dicentrarchus labrax, the type host, and Dentex dentex. The molecular analysis of complete Internal Transcribed Spacer sequences of ribosomal DNA revealed that specimens isolated from each host species form two well-defined groups, whose sequence divergence reaches 7.5%. The morphological study showed that the two groups can be distinguished by several characters, including the level of maximum body breadth, the relative position of the testes, the shape of the cirrus pouch, and the extent of the uterus. Multivariate analyses of morphometrics demonstrated consistency of most of the characters for discriminating the two groups. Our results show that C. labracis specimens isolated from D. labrax and D. dentex represent clearly distinct entities from molecular, morphological and statistical points of view, which has enabled us to describe a new species, Cainocreadium dentecis n. sp.

Three little known acanthostomine digeneans from Uranoscopus scaber L. in the western Mediterranean.

Three species of acanthostomine digeneans, Anisocoelium capitellatum from the gall-bladder and Anisocladium fallax and A. gracilis from the intestine, are redescribed from the teleost Uranoscopus scaber in the western Mediterranean. The latter two species, which have in the past been confused and synonymised, are distinguished clearly on the basis of morphology, size and site.

The life cycle of Opecoeloides columbellae (Pagenstecher, 1863) n. comb. (Digenea, opecoelidae): evidence from molecules and morphology.

The cosmopolitan digenean family Opecoelidae comprises several hundred species, whose adults live in the digestive tract of marine and freshwater fishes. The genus Opecoeloides Odhner, 1928 is represented in the Mediterranean by a single species, Opecoeloides furcatus (Bremser in Rudolphi, 1819), that has been recorded from six definitive hosts species. To see if this broad host range could be the result of an underestimation of species diversity, we obtained ITS1 ribosomal DNA sequences as well as morphological data from adult specimens of O. furcatus isolated from two definitive hosts species: Mullus surmuletus and Gaidropsarus mediterraneus. Sequence and morphological data were also obtained from several opecoelid cercariae and metacercariae occurring in different invertebrate hosts. The data presented here provide striking evidence that O. furcatus specimens isolated from the two host fishes represent distinct species. This argument is reinforced by the fact that cercariae corresponding to each of these adult species were found in two molluscan host-species, Columbella rustica and Mitrella scripta. These parasite species differ by several nucleotide substitutions and a 60 bp-long insertion in the ITS1. They also show clear morphological differences in testis and ovary shape, as well as in their mean dimensions. Here, we attribute the adult specimens found in G. mediterraneus to Opecoeloides columbellae (Pagenstecher, 1863) n. comb. This species was described and compared with O. furcatus from M. surmuletus. ITS1 sequence comparison allowed identification of the cercaria (occurring in C. rustica) and metacercaria (occurring in Hippolyte inermis) of O. columbellae n. comb.

The life cycle of Monorchis parvus (Digenea: Monorchiidae) demonstrated by developmental and molecular data.

Cercaria cerastodermae I, a digenean parasite of Cerastoderma edule, was recorded for the first time in the Atlantic Ocean off the Iberian peninsula. Sporocysts were present in the hemolymph of the digestive gland, gonad, gills, and foot of the mollusc. Most of the cercariae present within sporocysts were encysted as metacercariae. The corresponding adult stages were obtained after experimental infection of several Diplodus sargus artificially reared in fish farms and that had previously been protected against natural infections. Numerous adult specimens of Monorchis parvus were collected in Diplodus annularis along the French Mediterranean coast. Comparison of wild and experimental adults allowed the adult stage of Cercaria cerastodermae I to be identified as M. parvus. Another monorchid, Monorchis monorchis, a parasite of Spondyliosoma cantharus, was found in the same Mediterranean area and compared with M. parvus. Additionally, ITS1 nuclear ribosomal DNA sequences of C. cerastodermae I and of the adults collected in naturally infected D. annularis and S. cantharus were obtained. Sequence data indicate that C. cerastodermae I corresponds to the adult of M. parvus found in D. annularis and is clearly distinct from M. monorchis found in S. cantharus.

Methodology of head-up tilt testing potentiated with sublingual nitroglycerin in unexplained syncope.

Shortened head-up tilt testing (HUT) potentiated with sublingual nitroglycerin (60 degrees passive standing for 20 minutes followed, if negative, by 400 microg of sublingual nitroglycerin spray with the test continuing for another 20 minutes) differs from conventional nitroglycerin HUT for a shorter drug-free phase (20 vs 45 minutes). To compare the positivity rate of the 2 protocols, both tests were performed in a randomized sequence in 10 patients with unexplained syncope (study 1), and another 42 patients were randomly assigned either to conventional or to shortened nitroglycerin HUT (study 2). To evaluate the reproducibility of the shortened nitroglycerin HUT, another 38 patients with unexplained syncope underwent 2 consecutive tests within a 7+/-8 day interval (study 3). Finally, to evaluate the specificity of the test, 47 control subjects underwent shortened nitroglycerin HUT (study 4). Seven positive responses were observed during shortened nitroglycerin HUT, and there were 8 positive responses during conventional nitroglycerin HUT (p = NS) in the study 1 group. Fifteen positive (71%) responses, 5 negative responses, and 1 exaggerated response were observed during shortened nitroglycerin HUT; 16 positive (76%, p = NS vs. shortened nitroglycerin HUT), 3 negative, and 2 exaggerated responses were observed during conventional nitroglycerin HUT in the study 2 group. During the first test, 21 patients (55%) had a positive, 15 patients had a negative, and 2 patients had an exaggerated response in study group 3. During the second test, 15 positive (39%), 19 negative, and 4 exaggerated responses were observed. Thus, the reproducibility was 67% for a positive and 94% for a negative test. In control subjects, 2 positive (4%) responses, 38 negative, and 7 exaggerated responses were observed with a specificity of 96% in study group 4. In patients with unexplained syncope, shortened nitroglycerin HUT allowed a positivity rate similar to that of the conventional test. Moreover, the shortened test provided a high specificity and adequate reproducibility for both the positive and the negative responses.

Signaling through Ras is essential for ret oncogene-induced cell differentiation in PC12 cells.

Specific germline mutations of the receptor tyrosine kinase, Ret, predispose to multiple endocrine neoplasia types 2A and 2B and familial medullary thyroid carcinoma. The mechanisms by which different Ret isoforms (Ret-2A and Ret-2B) cause distinct neoplastic diseases remain largely unknown. On the other hand, forced expression of these mutated versions of Ret induces the rat pheochromocytoma cell line, PC12, to differentiate. Here we used an inducible vector encoding a dominant-negative Ras (Ras p21(N17)) to investigate the contributions of the Ras pathway to the phenotype induced in PC12 cells by the expression of either Ret-2A or Ret-2B mutants. We show that the Ret-induced molecular and morphological changes are both mediated by Ras-dependent pathways. However, even though inhibition of Ras activity was sufficient to revert Ret-induced differentiation, the kinetics of morphological reversion of the Ret-2B- was more rapid than the Ret-2A-transfected cells. Further, we show that in Ret-transfected cells the suc1-associated neurotrophic factor-induced tyrosine phosphorylation target, SNT, is chronically phosphorylated in tyrosine residues, and associates with the Sos substrate. These results indicate the activation of the Ras cascade as an essential pathway triggered by the chronic active Ret mutants in PC12 cells. Moreover, our data indicate SNT as a substrate for both Ret mutants, which might mediate the activation of this cascade.

New classification of haemodynamics of vasovagal syncope: beyond the VASIS classification. Analysis of the pre-syncopal phase of the tilt test without and with nitroglycerin challenge. Vasovagal Syncope International Study.

We believe that the pattern of blood pressure response to tilt during the time preceding the development of the vasovagal reaction may provide adjunctive diagnostic information. A group of 101 consecutive patients affected by syncope of uncertain origin underwent passive tilt testing for 45 min at 60 degrees followed, if negative, by oral (sublingual) trinitroglycerin (TNG) 0.4 microg with continuation of the test for 20 min. Three main patterns were observed: the classic (vasovagal) syncope pattern was observed in 36 patients who, during the preparatory phase, had a rapid and full compensatory reflex adaptation to upright position, resulting in stabilization of their blood pressure values until abrupt onset of the vasovagal reaction; the dysautonomic (vasovagal) syncope pattern was observed in 47 patients in whom steady-state adaptation to upright position was not possible. There was thus a progressive fall in their blood pressure until the occurrence of a typical vasovagal reaction; the orthostatic intolerance pattern was observed in 18 patients in whom there was a progressive fall in blood pressure, similar to that of the dysautonomic group, but this was not followed by a clear vasovagal reaction. Compared with the classic, the dysautonomic patients were older, had a higher prevalence of co-morbidities, a very much shorter history of syncopal episodes, and a prevalence of mixed and vasodepressor forms of the VASIS classification. The patients with orthostatic intolerance had clinical characteristics similar to the dysautonmic group but they could not be classified according to the VASIS classification. In conclusion, in patients with syncope, a variety of abnormal responses is observed during tilt testing, suggesting that different syndromes can be diagnosed by the test. A more detailed, although still arbitrary, classification may form the basis of a number of future drug and pacemaker trials, as well as help towards a greater understanding of the different mechanisms of tilt-induced syncope.

Acquisition of parasites correlated with social rank and behavioural changes in a fish species.

A survey of parasites was conducted on 258 Symphodus ocellatus (Teleostei: Labridae) collected in Corsica National Park (west Mediterranean). In addition, the total length, sex and social status were recorded for each individual fish. Three species of trematodes were found in the digestive tract. One of the parasites, Genitocotyle mediterranea, was only present, with one exception, in males of large size, and principally in the individuals that had the highest status and that were involved in nest construction. Two hypotheses are suggested to explain this particular distribution of a parasite: the immunocompetence handicap and the changing trophic behaviour as the fish grows.

Thymosin beta-10 gene overexpression is a general event in human carcinogenesis.

The beta-thymosins comprise a family of structurally related, highly conserved acidic polypeptides, originally isolated from calf thymus. Recently, we have demonstrated the overexpression of thymosin beta-10 (TB10) in rat thyroid transformed cell lines and in human thyroid carcinoma tissues and cell lines. To verify whether TB10 overexpression is a general event in the process of carcinogenesis, we have analyzed TB10 mRNA levels in human colon carcinomas, germ cell tumors of different histological types, breast carcinomas, ovarian carcinomas, uterine carcinomas, colon and esophageal carcinoma cell lines. Overexpression of the TB10 gene was detected in all of the neoplastic tissues and cell lines compared to the respective normal tissues. Moreover, the mouse model of skin carcinogenesis induced by the combined action of chemical carcinogens and phorbol esters was used to identify the stage of TB10 gene induction. The expression was almost undetectable in normal keratinocytes, its induction occurred even at the papilloma stage, however a further increased expression was observed in the carcinoma derived cell lines. Finally, immunohistochemical analysis of some breast, colon and ovary carcinoma samples by using specific anti-TB10 antibodies revealed the presence of the TB10 protein in all of the neoplastic tissues, but not in the respective normal tissues. Therefore the TB10 detection may be considered a potential tool for the diagnosis of several human neoplasias.

Community structure of digenean parasites of sparid and labrid fishes of the Mediterranean sea: a new approach.

The aim of this work was to study the structure of the parasite communities of Digeneans of 2 families of Teleost fishes (Sparidae and Labridae) of the Mediterranean sea. We tried to quantify the importance of both the microhabitat requirements of the parasite species and the effect of host biological factors on the parasite communities. We applied, for the first time in parasite community studies, the Canonical Correspondence Analysis (CCA) to analyse (i) the spatial distribution of parasite species within the digestive tract of the hosts; (ii) the host's biological factors (such as diet, host length, gregariousness and abundance) that may influence this spatial distribution of parasite species. Our results showed that potential microhabitats were vacant in the 2 host families studied revealing a lack of niche saturation because either there was little inter- and/or intraspecific competition or there were enough available space and resources within the host. Our results also indicated that the position of the parasite in the digestive tract is much more important than host biological factors for the structure of parasite community. Finally, we highlight the potential use of the CCA method for controlling for phylogenetic constraints in multi-species analyses.

The life-cycle of three species of the Mesometridae (Digenea) with comments on the taxonomic status of this family.

The intra-molluscan stages of three species of the Mesometridae Poche, 1926 are described. The corresponding adult stages are intestinal parasites of herbivorous sparid teleosts. The cercariae develop in prosobranch gastropods. The larvae of Elstia stossichianum occur in Vermetus triqueter, those of Wardula capitellata are parasites of Barleeia rubra and those of Centroderma spinosissima are found in three related rissoid hosts species: Rissoa ventricosa, R. auriscalpium and R. similis. The phylogenetic status of the Mesometridae in the Digenea is discussed in relation to larval and life-cycle characters.

Molecular identification of developmental stages in Opecoelidae (Digenea).

Nuclear ribosomal DNA sequences represent a useful tool for distinction of poorly differentiated developmental stages, such as trematode cercariae or metacercariae. Here, the complete internal transcribed spacer region of the ribosomal DNA (ITS 1 + 5.8S + ITS 2) was sequenced for 29 specimens of the digenean family Opecoelidae, including 16 adult specimens and 13 undescribed larval stages (nine cercariae and four metacercariae) occurring in various marine host organisms. Six cercariae and three metacercariae were found to match their corresponding adult form. This work also revealed that cercariae of the same species are able to infect more than one gastropod host species, suggesting that the specificity for the first intermediate host within the Digenea may be lower than previously thought.