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Hyriopsis (Hyriopsis) bialatus has been cultured during the mussel life cycle from glochidia to the adult stage with a low total survival of 6% up to 130-day-old juveniles. The main digestive enzymes (amylase and proteinases) were not detectable in one-day-old juveniles, and increased during development. The stomach, including digestive glands, was the major digestive organ for both carbohydrate and protein. The optimum conditions for amylase activity were 40°C and pH 7; for acidic proteinases they were 60°C and pH 5. Two main alkaline proteinases were found in the intestine, with optimum conditions of 30°C and pH 8 and 60°C and pH 8. To improve mussel survival by finding suitable phytoplankton species and age as food for juveniles and adults, an in-vitro digestibility test was performed on ten algal species three and seven days old using amylase and proteinases in crude enzyme extracts from different mussel life stages. Among the phytoplankton selected, the three most efficiently digested by juveniles were sevenday-old Chlorella sp.2, seven-day-old Chlorococcum sp. and seven-day-old Kirchneriella incurvata, in the ratio 1:1:3 for 30-day-old juveniles and 3:1:1 for 130-day-old juveniles. For the adult mussel, three-day-old Chlorella sp.2, seven-day-old Coccomyxa sp., and seven-day-old Monoraphidium sp., in the ratio 3:1:1, were the most digestible phytoplankton. Levels of in-vitro digestibility were related to the quality (not the concentrations) of carbohydrate and protein in the phytoplankton mixtures, and protein digestibility seemed to be the key factor determining food quality for the mussel.

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The insect Callosobruchus maculatus causes considerable damage to harvested mungbean seeds every year, which leads to commercial losses. However, recent studies have revealed that mungbean seeds contain alpha-amylase inhibitors that can inhibit the protein C. maculatus, preventing growth and development of the insect larvae in the seed, thus preventing further damage. For this reason, the use of alpha-amylase inhibitors to interfere with the pest's digestion process has become an interesting alternative biocontrolling agent. In this study, we have isolated and purified the alpha-amylase inhibitor from mungbean seeds (KPS1) using ammonium sulfate precipitation, gel filtration chromatography and reversed phase HPLC. We found that the alpha-amylase inhibitor, isolated as a monomer, had a molecular weight of 27 kDa. The alpha-amylase inhibitor was purified 750-fold with a final yield of 0.4 mg of protein per 30 g of mungbean seeds. Its specific activity was determined at 14.5 U (mg of protein)(-1). Interestingly, we found that the isolated alpha-amylase inhibitor inhibits C. maculatus alpha-amylase but not human salivary alpha-amylase. After preincubation of the enzyme with the inhibitor, the mungbean alpha-amylase inhibitor inhibited C. maculatus alpha-amylase activity by decreasing V(max) while increasing the K(m) constant, indicating that the mungbean alpha-amylase is a mix noncompetitive inhibitor. The in vivo effect of alpha-amylase inhibitor on the mortality of C. maculatus shows that the alpha-amylase inhibitor acts on C. maculatus during the development stage, by reducing carbohydrate digestion necessary for growth and development, rather than during the end laying/hatching stage. Our results suggest that mungbean alpha-amylase inhibitor could be a useful future biocontrolling agent.

Continuous noninvasive readout of biochemical events in body tissues is the goal of many techniques and optical and nuclear magnetic resonance (NMR) approaches seem to be at the forefront of these. Here we present a review of NMR methods for studying liver metabolism in vivo with special emphasis on methods of localizing the response appropriate to the liver itself and to the exclusion of surrounding tissues. The simplest and most direct method appears with the use of an implanted coil which enables a variety of NMR magnets to be used in this study.