The macauba palm (Acrocomia aculeata) is native of tropical America and is found mostly in the Cerrados and Pantanal biomes. The fruits provide an oily pulp, rich in long chain fatty acids, and a kernel that encompass more than 50% of lipids rich in medium chain fatty acids (MCFA). Based on biochemical and nutritional evidences MCFA is readily catabolized and can reduce body fat accumulation. In this study, an animal model was employed to evaluate the effect of Acrocomia aculeata kernel oil (AKO) on the blood glucose level and the fatty acid deposit in the epididymal adipose tissue. The A. aculeata kernel oil obtained by cold pressing presented suitable quality as edible oil. Its fatty acid profile indicates high concentration of MCFA, mainly lauric, capric and caprilic. Type 2 diabetic rats fed with that kernel oil showed reduction of blood glucose level in comparison with the diabetic control group. Acrocomia aculeata kernel oil showed hypoglycemic effect. A small fraction of total dietary medium chain fatty acid was accumulated in the epididymal adipose tissue of rats fed with AKO at both low and high doses and caprilic acid did not deposit at all.

Ammonium ions were incorporated into L-glutamate and alpha-ketoglutarate in epimastigote forms of Trypanosoma cruzi through the following enzymatic systems: NADPH and NADH-dependent glutamate dehydrogenase, NADPH-dependent glutamate synthase, L-glutamine synthetase and NADH-dependent glutamate synthase in order of decreasing specific activity (mumoles of product formed/min/mg protein). The pH optima and Km's for the glutamate dehydrogenase system were determined. Disc electrophoresis showed the presence of cathodic bands of GDH activity, which were highly dependent on NADP+.

SummaryThe beta-glucosidase of a Humicola sp. is partly characterized. The pH and temperature optima, thermal stability and Michaelis constants with p-nitrophenyl-beta-D-glucoside (PNPG) substrate suggest the existance of at least one extracellular and one intracellular enzyme. The extracellular activity is substantially more than that produced by Trichoderma reesei QM 9414.

Crop improvement in agriculture generally focuses on yield, seed quality and nutritional characteristics, as opposed to resistance to biotic stresses. Consequently, natural antifeedant toxins are often rare in seed material, with commercial crops being prone to insect pest predation. In the specific case of cowpea (Vigna unguiculata), smallholder cropping is affected by insect pests that reproduce inside the stored seeds. Entomopathogenic organisms can offer an alternative to conventional pesticides for pest control, producing hydrolases that degrade insect exoskeleton. In this study, protein secretions of the ascomycete Metarhizium anisopliae, which conferred bioinsecticidal activity against Callosobruchus maculatus, were characterized via 2D electrophoresis and mass spectrometry. Proteases, reductases and acetyltransferase enzymes were detected. These may be involved in degradation and nutrient uptake from dehydrated C. maculatus. Proteins identified in this work allowed description of metabolic pathways. Their potential applications in biotechnology include both novel compound development and production of genetically modified plants resistant to insect pests. INTRODUCTIONCallosobruchus maculatus is the main pest of cowpea (Vigna unguiculata), a common smallholder crop in Latin America and Africa (Delincee et al., 1998). During its larval stage, this weevil feeds on cotyledon material, causing significant economic losses through reduced seed quality and quantity (Credland et al., 1986). Control of C. maculatus currently relies upon application of chemical insecticides, biological control with bacteria, protozoa, nematodes, viruses and fungi (Kaya & Gaugler, 1993;Legner, 1995;Becker, 1998;Scholte et al., 2004;Jackai & Adalla, 1997;Galvan et al., 2006), and post-harvest treatment with ionizing radiation (Delincee et al., 1998). In recent years, the applicability of entomopathogenic fungi has been examined for biological control of coleopteran pests (Adane et al., 1996;Rice & Cogburn, 1999; Bourassa et al., 2001;Kassa et al., 2002). For example, strains of Metarhizium anisopliae from diverse geographical origins have been characterized according to their virulence against storage Bruchidae pests of maize, beans, rice and other agricultural crops (Cherry et al., 2005;Murad et al., 2006Murad et al., , 2007. These fungi secrete hydrolytic enzymes involved in insect attack, and offer potential for development of bioinsecticides and/or construction of pestresistant genetically modified plants (Murad et al., 2006(Murad et al., , 2007. In a previous study, we screened 10 M. anisopliae isolates for virulence against C. maculatus, and performed enzymic and 2D gel electrophoretic analyses of fungal secretions in the absence and presence of dehydrated C. maculatus (Murad et al., 2006). The results indicated that M. anisopliae strain CG34 has potential as a source of proteins for control of C. maculatus. Other authors have also utilized proteomic approaches in fungi for discovery of novel compounds with biological control p...

Digestive alpha-amylases play an essential role in insect carbohydrate metabolism. These enzymes belong to an endo-type group. They catalyse starch hydrolysis, and are involved in energy production. Larvae of Zabrotes subfasciatus, the Mexican bean weevil, are able to infest stored common beans Phaseolus vulgaris, causing severe crop losses in Latin America and Africa. Their alpha-amylase (ZSA) is a well-studied but not completely understood enzyme, having specific characteristics when compared to other insect alpha-amylases. This report provides more knowledge about its chemical nature, including a description of its optimum pH (6.0 to 7.0) and temperature (20-30 degrees C). Furthermore, ion effects on ZSA activity were also determined, showing that three divalent ions (Mn2+, Ca2+, and Ba2+) were able to enhance starch hydrolysis. Fe2+ appeared to decrease alpha-amylase activity by half. ZSA kinetic parameters were also determined and compared to other insect alpha-amylases. A three-dimensional model is proposed in order to indicate probable residues involved in catalysis (Asp204, Glu240, and Asp305) as well other important residues related to starch binding (His118, Ala206, Lys207, and His304).