Diapause as escape strategy to exposure to toxicants: response of Brachionus calyciforus to arsenic

Invertebrate organisms commonly respond to environmental fluctuation by entering diapause. Production of diapause in monogonont rotifers involves a previous switch from asexual to partial sexual reproduction. Although zooplankton have been used in ecotoxicological assays, often their true vulnerability to toxicants is underestimated by not incorporating the sexual phase. We experimentally analyzed traits involved in sexual reproduction and diapause in the cyclically parthenogenetic freshwater rotifer, Brachionus calyciflorus, exposed to arsenic, a metalloid naturally found in high concentrations in desert zones, focusing on the effectiveness of diapause as an escape response in the face of an adverse condition. Addition of sublethal concentrations of arsenic modified the pattern of diapause observed in the rotifer: investment in diapause with arsenic addition peaked earlier and higher than in non-toxicant conditions, which suggests that sexual investment could be enhanced in highly stressed environmental conditions by increased responsiveness to stimulation. Nevertheless, eggs produced in large amount with arsenic, were mostly low quality, and healthy-looking eggs had lower hatching success, therefore it is unclear whether this pattern is optimum in an environment with arsenic, or if rather arsenic presence in water bodies disturbs the optimal allocation of offspring entering diapause. We observed high accumulation of arsenic in organisms exposed to constant concentration after several generations, which suggests that arsenic may be accumulated transgenerationally. The sexual phase in rotifers may be more sensitive to environmental conditions than the asexual one, therefore diapause attributes should be considered in ecotoxicological assessment because of its ecological and evolutionary implications on lakes biodiversity

Gonadotrophin-releasing hormone immunoreactivity in the brain of the tropical freshwater fish, Pygocentrus notatus (Teleostei-Characidae)

The distribution of GnRH in the brain of the teleost Pygocentrus notatus was demonstrated with the avidin-biotin peroxidase immunocytochemical method using highly specific antibody against synthetic mammalian GnRH. Optimal immunoreaction was obtained using: 1) Bouin's fluid for fixation; 2) repeated incubation with primary antiserum; 3) the use of a detergent in the dilution buffer; 4) the high sensitivity of the avidin-biotin immunoperoxidase method with the cobalt intensification of 3-3'diaminobenzidine tetrahydrochloride; and 5) the use of primary antibody with high specificity. GnRH-immunoreactive (GnRH-ir) in cells andlor axons was observed in al1 main brain regions. In the forebrain, GnRH-ir was located in a network extending from the caudal part of the olfactory bulb to the telencephalon. GnRH-ir fibres were also observed in the optic tectum, cerebellum and hypothalamus. Two groups of neurona1 cell bodies were identified. One group was located in the antero-ventral telencephalon corresponding to the nucleus olfactoretinalis. The second group was found in the rostrodorsal hypothalamus. No GnRH-ir material was detected in the pituitary gland, thus confirming the results of previous studies on brain GnRH-ir distribution obtained by radioimmunoanalysis in this species. These results demonstrate a high degree of similarity between the GnRH systems of P. notatus and other teleost species

Leukocyte immunophenotypes in bronchoalveolar lavage fluid and peripheral blood of paracoccidioidomycosis, sarcoidosis and silicosis

Leukocyte subsets in bronchoalveolar lavage (BAL) fluid and peripheral blood of patients with paraccoccidioidomycosis, sarcoidosis and silicosis were characterized using monoclonal antibodies and an immunoperoxidase technique. In paraccocidioidomycosis, the number of T-helperl inducer CD4-positive lymphocytes was lower in peripheral blood than in BAL fluid. Additional analysis showed that the expression of HLA-DR was very similar in alveolar macrophages, lung and blood T-cells. In sarcoidosis and silicosis there were higher proportions of T-helperlinducer cells in peripheral blood than in BAL fluid. The alterations in the T-helperlinduceriT-suppressorl cytotoxic CD4lCD8 ratio in sarcoidosis and silicosis were more appreciable in peripheral blood than in BAL fluid, contrasting with the results in paracoccidioidomycosis. The expression of HLA-DR by alveolar macrophages in sarcoidosis was the highest of al1 the diseases studied. No statistically significant differences were observed between chronic multifocal and chronic unifocal paracoccidioidomycosis disease, stage 11 and stage 111 sarcoidosis, and chronic and accelerated silicosis. The three granulomatous diseases analyzed had a few alveolar macrophages expressing the CD4 molecule on their surface. These findings and the technique of analyzing both peripheral blood and BAL leukocyte subsets may help to understand the pathogenesis of interstitial lung diseases

Therapy of Venezuelan patients with severe mucocutaneous or early lesions of diffuse cutaneous leishmaniasis with a vaccine containing pasteurized Leishmania promastigotes and bacillus Calmette-Guerin: preliminary report

Severe mucocutaneous (MCL) and diffuse (DCL) forms of American cutaneous leishmaniasis (ACL) are infrequent in Venezuela. Chemotherapy produces only transitory remission in DCL, and occasional treatment failures are observed in MCL. We have evaluated therapy with an experimental vaccine in patients with severe leishmaniasis. Four patients with MCL and 3 with early DCL were treated with monthly intradermal injections of a vaccine containing promastigotes of Leishmania (Viannia) braziliensis killed by pasteurization and viable Bacillus Calmette- Guerin. Clinical and immunological responses were evaluated. Integrity of protein constituents in extracts of pasteurized promastigotes was evaluated by gel electrophoresis. Complete remission of lesions occurred after 5-9 injections in patients with MCL or 7-10 injections in patients with early DCL. DCL patients developed positive skin reactions, average size 18.7 mm. All have been free of active lesions for at least 10 months. Adverse effects of the vaccine were limited to local reactivity to BCG at the injection sites and fever in 2 patients. Extracts of pasteurized and fresh promastigotes did not reveal differences in the integrity of protein components detectable by gel electrophoresis. Immunotherapy with this modified vaccine offers an effective, safe option for the treatment of patients who do not respond to immunotherapy with vaccine containing autoclaved parasites or to chemotherapy