This study aims to explain the effects of silicon on chlorophyll and to measure gas exchange and carbohydrate levels in two Lycopersicon esculentum cultivars that are exposed to drought. The experimental design used in this study was a randomised combination of five different water and silicon conditions (control, water deficit + 0.00 μmol Si, water deficit + 0.25 μmol Si, water deficit + 1.00 μmol Si, and water deficit + 1.75 μmol Si) applied to the two cultivars (Super Marmante and Santa Cruz). Parameters measured were gas exchanges, chlorophylls, and total soluble carbohydrates. Silicon at concentrations of 0.25, 1.00, and 1.75 μmol induced a gradual increase in the total chlorophyll levels. A correlation analysis revealed a linear, positive interaction between the leaf water potential and the total chlorophyll (r = 0.71; P < 0.05). This study confirmed the hypothesis that silicon has a beneficial effect with regard to chlorophyll. Under water-deficient conditions, both cultivars showed an increase in chlorophyll a when treated with silicon in addition to changes in the total chlorophyll levels. These results were supported by the change in leaf water potential. In addition, a reduction of the effects of water restriction was also observed in the transpiration rate, the stomatal conductance and in the levels of total carbohydrates.

Schistosomiasis continues to be a significant public health problem that affects 200 million people worldwide. This is one of the most important parasitic diseases, and one whose effective control is unlikely in the absence of a vaccine. In this study, we have isolated a cDNA clone encoding the Schistosoma mansoni Sm21.6 protein that has 45% and 44% identity with Sm22.6 and Sj21.7 EF-hand containing antigens, respectively. Confocal microscopy analysis revealed that Sm21.6 is a membrane-associated protein localized on the S. mansoni adult worm. Mouse immunization with rSm21.6 induced a mixed Th1/Th2 cytokine profile and no protection against infection. However, vaccination with rSm21.6 reduced by 28% of liver granuloma numbers, 21% of granuloma area and 34% of fibrosis. Finally, rSm21.6 was recognized by sera from individuals resistant to reinfection compared with patients susceptible to reinfection and this molecule should be further studied as potential biomarker for disease resistance. In conclusion, Sm21.6 is a new tegument protein from S. mansoni that plays an important role in reducing pathology induced by parasite infection.

Corynebacterium pseudotuberculosis is the etiological agent of caseous lymphadenitis (CLA), a chronic small ruminant's disease. C. pseudotuberculosis Hsp60 expressed in E. coli was purified and tested as a vaccine candidate against CLA. Immunization of BALB/c mice with recombinant Hsp60 (rHsp60) induced a significant anti-Hsp60 IgG response, with greater production of IgG1 than of IgG2a. Cell-mediated immune responses induced by immunization were characterized by elevated production of gamma interferon (IFN-) and interleukin (IL)-10, while IL-4 concentrations were not significantly increased. Otherwise, mice challenged with 10 6 c.f.u. of a virulent C. pseudotuberculosis strain developed abscesses and other signs of morbidity at the site of inoculation. The rate of survival of the animals immunized with rHsp60 was slightly higher than that of mice immunized with PBS; however, all the animals died within two weeks after challenge. We concluded that subcutaneous administration of rHsp60 does not induce effective protection against intraperitoneal infection with C. pseudotuberculosis.

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The yeastKluyveromyces lactis was cultured in cheese whey and b-galactosidase was extracted from cells by an organic solvent procedure. Under optimum conditions (pH 8.5, 25C), approximately 90% of the intracellular b-galactosidase activity was released into 0.1 M potassium phosphate solution with 2% chloroform after 9 h. The cell-free extract containing b-galactosidase activity was concentrated and the enzyme partially characterized. This enzyme has exhibited an optimum activity at a pH range of 6.2-6.6 and temperature of 40-45C on O-nitrophenyl-b-D-galctopyranoside. The maximum enzyme activity in milk was found at 45C and the concentrated enzymatic extract was found to have 19 U/mg protein. A feasible preparation for commercial application containing 20% glycerol maintained 89% of activity after 2 months at 4C, demonstrating stability. This preparation analyzed on 5% nondenaturing polyacrylamide gel electrophoresis exhibited two bands suggesting two aggregation forms with b-galactosidase activity. PRACTICAL APPLICATIONSKluyveromyces lactis yeast cells are a safe source of b-galactosidase for food and pharmaceutical industries. Their application to prior hydrolysis of lactose in milk products has become commonplace in alleviating the symptoms of lactose intolerance. It is also of great interest to prevent lactose crystallization in concentrated or frozen dairy products such as condensed 1 Corresponding