Els isòtops radiogènics(Sr i Nd) en diferents contextes geodinàmics: Illes Canaries i Vesuvi. Preparació i anàlisi de mostres mitjançant la tècnica analítica TIMS

Projecte de recerca elaborat a partir d’una estada l’ Osservatorio Vesuviano (Nàpols, Italia) entre novembre del 2006 i març del 2007. Un dels objectius principals de l’estada ha estat conèixer la tècnica analítica Thermal Ionisation Mass Spectrometry (TIMS ) per l’anàlisi d’isòtops radiogènics (Sr i Nd). Aquesta estada ha permès aprendre tant la part de preparació de les mostres, com la part d’utilització i programació de l’instrument. Inicialment en el projecte es va programar l’anàlisi dels isòtops radiogènics en laves i xenòlits de l’illa de Gran Canaria (Illes Canàries) amb l’objectiu de modelar geoquímicament el mantell terrestre sota les illes Canàries. Finalment, i a part de les mostres inicials de Gran Canaria, es van incloure mostres del volcà Vesuvi per tal de concloure un projecte iniciat el 2003 amb el Professor Giovanni Orsi i la Professora Lucia Civetta. L’estudi dels isòtops radiogènics en contextes geodinàmics tant diferents ha permès comparar la variació dels isòtops radiogènics de Sr i Nd que existeix entre volcanisme d’ intraplaca (Illes Canàries) i volcanisme en zones convergents (Vesuvi).

Analysis of toxoplasma gondii proteins after Triton X-114 solubilization and hidropholic chromotograhy

The distribution of the surface proteins of toxoplasma gondii radiodinated were studied using the phase separation technique and ability of binding in the phenyl-Sepharose column. Eight polypeptides with Mr 22 to 180 distributed exclusively in the detergent rich-phase, while six polypeptides with mol. wt. 15,000 to 76,000 distributed exclusively in the detergent poor-phase. Twopolypeptides with 15,000 and 70,000 distributed on both phase. All the polypeptides present in the detergent rich-phase binding in the phenyl-Sepharose column, and can be isolated in two peak according with their relative hydrophobicities.two polypeptides hydrophobic with Mr 60 and 66 recognized by human serum were isolated by the association of the two technique. Our result showed that the surface proteins of t. gondii present different degrees of hydrophobicity and that the use of hydrophobic interaction chromatography after Triton X-114 extraction may be an important isolation method of membrane proteins.

Characterization of plasma menbrane polypeptides of trypanosoma from bats

Cell surface proteins of Trypanosoma dionisii, Trypanosoma vespertilionis and Trypanosoma sp. (M238) were radiodinated and their distribution both in the detergent-poor (DPP) and dertergent-enriched phase (DRP) was studied using a phase separation technique in Triton X-114 as well as polyacrylamide gel electrophoresis in sodium dodecyl sulphate (SDS-PAGE). Significant differences were observed in the proteins present in the DRP when the three species of trypanosoma were compared. Two major bands with 88 and 70 KDa were observed in T. sp. (M238) but were not detectable in T. dionisii and T. vespertilionis. Three polypeptides whith 96, 77 and 60 KDa were identified in the DRP of T. vespertilionis. Three major bands with 84, 72 and 60 KDa were observed in the DRP of T. dionisii. Two polypeptides with 34-36 KDa present in the DPP, were observed in the three Trypanosome species analyzed. Our observations show that T. sp. (M238) has characteristic surface polypeptides not found in T. vespertilionis.

Technique for the detection of Toxoplasma gondii antigens in mouse urine

A simple and rapid staphylococcal coagglutination test for the detection of Toxoplasma gondii antigens in mice urine is described. A suspension of protein-A containing Staphylococcus aureus coated with rabbit hyperimmune serum was used as reagent. The sensitivity of the antigen assay was found to be at least 118 ng of the antigen protein per ml. No coagglutination was observed when the reagent was challenged against antigenic solutions of other parasites. The suitability of the method for detecting antigens of T. gondii in urine samples was studied by experimental toxoplasma infection in mice. Before the staphylococcal test, the urine samples were double serially diluted in 0.1 M PBS. From the second day on all samples from infected mice were positive at 1/16 dilution. At this dilution, all samples from non infected mice were negative or did not produce coagglutination. This method might be used in the rapid etiological diagnosis also in human cases of acute toxoplasmosis.

Identification and characterization of sex-linked proteins of Schistosoma mansoni

The proteins of adults worms (male and female) of two isolates (BH and RJ) of Shistosoma mansoni were extracted using Triton X-114 phase separation. The SDS-polyacrilamide gel electrophoresis profiles of the three phases (detergent, aqueous and insoluble proteins) obtained were compared after Coomassie blue and silver staining, surface radioiodination and Western blotting. No major differences were detected between the 2 isolates. Of the 25 or more proteins which partitioned into the detergent phase, only about 8 proteins could be surface radiodinated on live adult worms. A comparison was also made between the profiles of mael and females worms, isolated from bisexually infected mice. Two major female-specific and one male-specific band were detected by silver and/or Coomassie staining. The female bands, 32 KDa and 18 KDa, partitioned into the detergent and aqueous phase, respectively. The male-specific band of 42 KDa remained in the insoluble phase. Antigenic differences between male and females protins were detected by Western vlotting using a sera from infected Nectomys squamipes.

Migration and trade: Theory with an Application to the Eastern- Western European Integration

The remarkable increase in trade flows and in migratory flows of highly educated people are two important features of globalization of the last decades. This paper extends a two-country model of inter- and intraindustry trade to a rich environment featuring technological differences, skill differences and the possibility of international labor mobility. The model is used to explain the patterns of trade and migration as countries remove barriers to trade and to labor mobility. We parameterize the model to match the features of the Western and Eastern European members of the EU and analyze first the effects of the trade liberalization which occured between 1989 and 2004, and then the gains and losses from migration which are expected to occur if legal barriers to labor mobility are substantially reduced. The lower barriers to migration would result in significant migration of skilled workers from Eastern European countries. Interestingly, this would not only benefit the migrants and most Western European workers but, via trade, it would also benefit the workers remaining in Eastern Europe. Key Words: Skilled Migration, Gains from Variety, Real Wages, Eastern-Western Europe. JEL Codes: F12, F22, J61.

A new host of Trypanosoma cruzi from Jujuy, Argentina: octodontomys gliroides (Gervais & D'Orbigny, 1844) (Rodentia, Octodontidae)

To identify wild hosts of Trypanosoma cruzi, surveys were conducted in the subandean valleys of Jujuy Province, Argentina, between June 1986 and March 1987. Seventy two mammals from 13 different species were examined by xenodiagnosis. Fifty two of them were mostly roedents trapped at the localities of Maimará, León and Tilcara, and the remainder had been kept in captivity at the Estación Biológica Experimental, in Jujuy. Trypanosoma cruzi infection was detected only in 2 Octodontomys gliroides (2 pos./8 exam. 25%) from all 72 examined mammals. Isolates were called Octodontomys Argentina 1 and 2 (OA1 and OA2). Both infected animals were caught at the archaelogical ruin of Pucará, at Tilcara. Repeated searches for triatomines in the ruin itself and in neighbour houses rendered negative results. Groups of mice inoculated with either OA1 or OA2 isolates became infected between 7 (OA1) to 12 days (OA2) postinoculation PI. Parasitemia peaks were observed between day 12th - 14th PI. Scarce amastigote nests were found in myocardium and skeletal muscle. Mortality was observed only for mice inoculated with OA1. Isoenzyme patterns of OA1 and OA2 were identical to one found in dogs and slightly different from that of human parasites in Argentina. Bones from Octodontomys sp., were recently found in a cave, dated 10200-8600 BC, in Pumamarca, near Tilcara, Jujuy. There are evidences that O. gliroides cohabited with man in ancient times and was associated to the domestic cycle of T. cruzi transmission, playing a role like that of domestic cavies. in Bolivia.

Immunological profiles of patients from endemic areas infected with Schistosoma mansoni

Crude extracts of eggs (SEA) adult worms (SWAP) or cercariae (Cerc) have been used to stimulate Peripheral Blood Mononuclear cells (PBMC) and have provided rather distinct profiles of responses in different types of patients. In genenral it is clear that patients with early infections respond strongly to SEA while response to SWAP are developed more slowly. As infection progresses into the more chronic phases, a general pattern is seen whic leads to lower anti-SEA proliferative responses in the face of higher responses to SWAP and variable anti-cerc responsiveness. Cured not re-exposed patients express very high levels of anti-SEA proliferation. It has recently been seen that those individuals who live in endemic areas and have continued water contact, but are reapeatedly stool-negative (who are presumed to have self-cured or be putatively resistant; endemic normals) are strongly responsive to antigenic extracts, particularly to SEA. Furthermore, our results show that endemic normal individuals have significantly higher IFN gamma production upon PBMC stimulation with schistosome antigens than infected individuals. With the emergence of more studies it is becoming apparent that both the intensity and the prevalence of a given area may influence or shape the general responsiveness of the population under study.

Human schistosomiasis mansoni: studies on in vitro granuloma modulation

Infection with Schistosoma mansoni induces humoral and T cell mediated responses and leads to delayed hipersensitivity that results in granulomatous inflamatory disease around the parasite eggs. Regulation of these responses resulting in a reduction in this anti-egg inflamatory disease is appsrently determined by idiotypic repertoires of the patient, associated with genetic background and multiple external factors. We have previously reported on idiotype/anti-idiotype-receptor transactions in clinical human schistosomiasis. These findings support a hypothesis that anti-SEA cross-reactive idiotypes develop in some patients during the course of a chronic infection and participate in regulation of anti-SEA cellular immune responses. We repport here on experiments wich extend those observations to the regulation of granulomatous hypersensitivity measured by an in vitro granuloma model. T cells from chronic intestinal schistosomiasis patients were stimulated in vitro with anti-SEA idiotypes and assayed in an autologous in vitro granuloma assay for modulation of granuloma formation. These anti-SEA idiotype reactive T cells were capable of regulating autologous in vitro granuloma formation. This regulatory activity, initiated with stimulatory anti-SEA idiotypic antibodies, was antigenically specific and was dependent on the present of intact (F(ab')2 immunoglobulin molecules. The ability to elicit this regulatory activity appears to be dose dependent and is more easily demonstrated in chronically infected intestinal patients or SEA sensitized individuals. These data support the hypothesis that anti-SEA cross reactive idiotypes are important in regulating granulomatous hypersensitivy in chronic intestinal schistosomiasis patients and these cross-reactive idiotypes appear to play a major role in cell-cell interactions which result in the regulation of anti-SEA cellular immune responses.

Dispersive flight and house invasion by Triatoma guasayana and Triatoma sordida in Argentina

Flight activity and invasion of houses by Triatoma sordida and T. guasayana were studied in the Province of Santiago del Estero, Argentina. Spontaneous findings of both species in houses were recorded from 1982 to 1989. Light trap collections were performed in 1982, 1983 and 1984, at the woods surrounding the settlements of Amamá (43 houses) and Trinidad (19 houses). Most of the 101 triatomines collected, were unfed and negative for Trypanosoma cruzi. T. guasayana predominated over T. sordida, and both appeared on the lighted screens between 19-31 min (mean 24) after dusk and the catch time was 30-45 min. Although entomological evaluation of 41 houses at Amamá performed in September 1985, just before insecticidal spraying, showed that Triatoma infestans predominated, adults of T. guasayana were collected in sleeping places, in 7 houses (17%). Most triatomines invading houses from then up to 1990 were flying T. guasayana (20/27) and females outnumbered males. Three non infected T. guasayana females were fed on man and two T. guasayana males positive for "T. cruzi like" trypanosomes were unfed. Therefore, visiting hungry adults could transmit T. cruzi to people and introduce wild parasites to the domestic cycle. T. guasayana stands as the main potential substitute of T. infestans in the studied area, and it might play there the same role as T. sordida in Brazil.

Partial isolation and some properties of enterotoxin produced by Bacillus cereus strains

Extracellular proteins produced by Bacillus cereus AL-42 and AL-15 were fractioned by chromatography on QAE-Sephadex and Sephadex G75. This last chromatographic process resulted in three peaks. The major peak showed vascular permeability activity to rabbits, lethality to mice, and cytotoxicity to Vero and Hela cells. The analysis by SDS-PAGE after ultrafiltration confirm recent findings that the enterotoxin is a compound with molecular mass > 30.000.