Composition, ileal amino acid digestibility and nutritive value of organically grown legume seeds and conventional rapeseed cakes for pigs

Selostus: Palkoviljojen ja rypsipuristeiden koostumus, aminohappojen ohutsuolisulavuus sekä rehuarvo sikojen ruokinnassa

Apparent ileal amino acid digestibility and the nutritive value of the triticale cultivars Moreno and Ulrika for growing-finishing pigs

Selostus: Ruisvehnälajikkeiden Ulrika ja Moreno rehuarvo lihasikojen ruokinnassa

The effects of mutated cationic amino acid transporter y+LAT1 at the cellular and systemic level

y+LAT1 is a transmembrane protein that, together with the 4F2hc cell surface antigen, forms a transporter for cationic amino acids in the basolateral plasma membrane of epithelial cells. It is mainly expressed in the kidney and small intestine, and to a lesser extent in other tissues, such as the placenta and immunoactive cells. Mutations in y+LAT1 lead to a defect of the y+LAT1/4F2hc transporter, which impairs intestinal absorbance and renal reabsorbance of lysine, arginine and ornithine, causing lysinuric protein intolerance (LPI), a rare, recessively inherited aminoaciduria with severe multi-organ complications. This thesis examines the consequences of the LPI-causing mutations on two levels, the transporter structure and the Finnish patients’ gene expression profiles. Using fluorescence resonance energy transfer (FRET) confocal microscopy, optimised for this work, the subunit dimerisation was discovered to be a primary phenomenon occurring regardless of mutations in y+LAT1. In flow cytometric and confocal microscopic FRET analyses, the y+LAT1 molecules exhibit a strong tendency for homodimerisation both in the presence and absence of 4F2hc, suggesting a heterotetramer for the transporter’s functional form. Gene expression analysis of the Finnish patients, clinically variable but homogenic for the LPI-causing mutation in SLC7A7, revealed 926 differentially-expressed genes and a disturbance of the amino acid homeostasis affecting several transporters. However, despite the expression changes in individual patients, no overall compensatory effect of y+LAT2, the sister y+L transporter, was detected. The functional annotations of the altered genes included biological processes such as inflammatory response, immune system processes and apoptosis, indicating a strong immunological involvement for LPI.

Andean indigenous food crops: nutritional value and bioactive compounds

The Andean area of South America is a very important center for the domestication of food crops. This area is the botanical origin of potato, peanut and tomato. Less well- known crops, such as quinoa (Chenopodium quinoa), kañiwa (Chenopodium pallidicaule) and kiwicha (Amaranthus caudatus), were also domesticated by ancient Andean farmers. These crops have a long history of safe use with the local populations and they have contributed to the nutrition and wellbeing of the people for centuries. Several studies have reported the nutritional value of Andean grains. They contain proteins with a balanced essential amino acid composition that are of high biological value, good quality oil and essential minerals, for example iron, calcium and zinc. They are potential sources of bioactive compounds such as polyphenols and dietary fiber. The main objective of the practical work was to assess the nutritional value of Andean native grains with a special emphasis on the bioactive components and the impact of processing. The compounds studied were phenolic acids, flavonoids, betalains and dietary fiber. The radical scavenging activity was measured as well. Iron, calcium and zinc content and their bioavailability were analyzed as well. The grains were processed by extrusion with the aim to study the effect of processing on the chemical composition. Quinoa, kañiwa and kiwicha are very good sources of dietary fiber, especially of insoluble dietary fiber. The phenolic acid content in Andean crops was low compared with common cereals like wheat and rye, but was similar to levels found in oat, barley, corn and rice. The flavonoid content of quinoa and kañiwa was exceptionally high. Kiwicha did not contain quantifiable amounts of these compounds. Only one variety of kiwicha contained low amounts of betalains. These compounds were not detected in kañiwa or quinoa. Quinoa, kañiwa and kiwicha are good sources of minerals. Their calcium, zinc and iron content are higher than the content of these minerals in common cereals. In general, roasting did not affect significantly mineral bioavailability. On the contrary, in cooked grains, there was an increase in bioavailability of zinc and, in the case of kañiwa, also in iron and calcium bioavailability. In all cases, the contents of total and insoluble dietary fiber decreased during the extrusion process. At the same time, the content of soluble dietary fiber increased. The content of total phenolics, phytic acid and the antioxidant activity decreased in kiwicha varieties during the extrusion process. In the case of quinoa, the content of total phenolic compounds and the radical scavenging activity increased during the extrusion process in all varieties. Taken together, the studies presented here demonstrate that the Andean indigenous crops have excellent potential as sources of minerals, flavonoids and dietary fiber. Further studies should be conducted to characterize the phenolic compound and antioxidant composition in processed grains and end products. Quinoa, kañiwa and kiwicha grains are consumed widely in Andean countries but they also have a significant, worldwide potential as a new cultivated crop species and as an imported commodity from South America. Their inclusion in the diet has the potential to improve the intake of minerals and health-promoting bioactive compounds. They may also be interesting raw materials for special dietary foods and functional foods offering natural sources of specific health-promoting components.

Inactive endosialidase-based detection of bacterial and oncofetal polysialic acid

Polysialic acid is a carbohydrate polymer which consist of N-acetylneuraminic acid units joined by alpha2,8-linkages. It is developmentally regulated and has an important role during normal neuronal development. In adults, it participates in complex neurological processes, such as memory, neural plasticity, tumor cell growth and metastasis. Polysialic acid also constitutes the capsule of some meningitis and sepsis-causing bacteria, such as Escherichia coli K1, group B meningococci, Mannheimia haemolytica A2 and Moraxella nonliquefaciens. Polysialic acid is poorly immunogenic; therefore high affinity antibodies against it are difficult to prepare, thus specific and fast detection methods are needed. Endosialidase is an enzyme derived from the E. coli K1 bacteriophage, which specifically recognizes and degrades polysialic acid. In this study, a novel detection method for polysialic acid was developed based on a fusion protein of inactive endosialidase and the green fluorescent protein. It utilizes the ability of the mutant, inactive endosialidase to bind but not cleave polysialic acid. Sequencing of the endosialidase gene revealed that amino acid substitutions near the active site of the enzyme differentiate the active and inactive forms of the enzyme. The fusion protein was applied for the detection of polysialic acid in bacteria and neuroblastoma. The results indicate that the fusion protein is a fast, sensitive and specific reagent for the detection of polysialic acid. The use of an inactive enzyme as a specific molecular tool for the detection of its substrate represents an approach which could potentially find wide applicability in the specific detection of diverse macromolecules.