Bioavailability of lysine in heat-treated foods and feedstuffs

During the processing of foodstuffs, lysine can react with other compounds present to form nutritionally unavailable derivatives, the most common example of which are Maillard products. Maillard products can cause serious problems when determining the available lysine content of processed foods or feedstuffs as they can revert to lysine during amino acid analysis. Several methods have been developed to determine the dietary lysine available for the metabolic processes of animals including animal growth-based assays, reactive lysine chemical methods and digestibility assays. However, growth-based assays are laborious, highly variable and tend to determine utilization rather than availability. Chemically reactive lysine assays do accurately determine the unmodified lysine in a food or feedstuff, but do not determine available lysine as they incorrectly assume that reactive lysine digestion and absorption is 100%. Ileal digestibility assays measure digestible total lysine rather than digestible reactive lysine (available lysine) and so are inaccurate, especially when applied to processed protein sources. This thesis describes the development of a true ileal digestible reactive lysine assay for determining dietary (bio)available lysine. This assay couples the guanidination reaction, for determining reactive lysine, with a true ileal digestibility assay. The resulting apparent digestibility estimate is corrected to a true digestibility value by accounting for the endogenous ileal lysine flow. Selected reaction conditions for the guanidination of lysine in a heated lactose/casein mixture and digesta of rats fed unheated casein and heated lactose/casein was examined. Overall, suitable reaction conditions were 0.6 M O-methylisourea for 7 d in a shaking waterbath at 21 ± 2 °C with an O-methylisourea to lysine ratio of 1000 and a reaction mixture pH of 10.6 for casein and heated lactose/casein and 11.0 for digesta. The accuracy of the guanidination method for determining reactive lysine in a range of “ready-to-eat ” cereal-based breakfast foods and selected feedstuffs was tested by comparison with the reactive lysine content of the same protein sources when determined using the fluorodinitrobenzene method. Overall, there was excellent agreement between the two methods. The accuracy of the newly developed bioassay for determining digestible reactive (available) lysine for predicting lysine deposition was also tested using a heated skim milk powder. The true ileal total and reactive lysine digestibilities were determined for the heated skim milk powder which was then fed to pigs, along with two control diets which were formulated based on either total lysine digestibility or reactive lysine digestibility. All diets were limiting in lysine. The pigs fed the heated skim milk powder deposited the same (P > 0.05) amount of lysine (9.1 g d-1) as the pigs fed the control diet that was formulated based on reactive lysine digestibility (9.1 g d-1) but deposited significantly (P The new assay demonstrated that for a range of milk protein-based foods, there was little difference between digestible total lysine and digestible reactive lysine for most of the milk products tested. In contrast, for a range of “ready-to-eat” cereal-based breakfast foods, available lysine was 5 – 50% lower than that determined using the traditional assay, which is of concern given that breakfast cereals are perceived to be “healthy” foods. Similarly, the available lysine content of a range of moist and dry commercial cat foods was significantly (P <br/

Social Status and Badge Design

Many websites rely on user-generated content to provide value to consumers. These websites typically incentivize participation by awarding users badges based on their contributions. While these badges typically have no explicit value, they act as symbols of social status within a community. In this paper, we consider the design of badge mechanisms for the objective of maximizing the total contributions made to a website. Users exert costly effort to make contributions and, in return, are awarded with badges. A badge is only valued to the extent that it signals social status and thus badge valuations are determined endogenously by the number of users who earn each badge. The goal of this paper is to study the design of optimal and approximately badge mechanisms under these status valuations. We characterize badge mechanisms by whether they use a coarse partitioning scheme, i.e. awarding the same badge to many users, or use a fine partitioning scheme, i.e. awarding a unique badge to most users. We find that the optimal mechanism uses both fine partitioning and coarse partitioning. When status valuations exhibit a decreasing marginal value property, we prove that coarse partitioning is a necessary feature of any approximately optimal mechanism. Conversely, when status valuations exhibit an increasing marginal value property, we prove that fine partitioning is necessary for approximate optimality

Acetyl-CoA carboxylase in the photosynthetic tissue of maize :a thesis presented in partial fulfilment of the requirement for the degree of Master of Science in biochemistry at Massey University

The aim of this study was, a). to examine further, aspects of the role of acetyl-CoA carboxylase in the regulation of fatty acid synthesis in the provision of acyl lipid for plastid development, and b}. to purify acetyl-CoA carboxylase from maize leaves using the affinity methods which have been used successfully to purify the enzyme from animal tissues. In a constant weight of tissue, carboxylase activity decreased 7.6-fold over the period of 4 to 12 days after sowing, while total acetyl-CoA carboxylase activity increased 9-fold in maize seedlings over the period of 4 to 8 days with no further increase up to day 12. Protein levels decreased 3-fold over the growth period examined, while specific activity was constant at 27.2 to 28.3nmol/min/mg of protein between 4 and 6 days, before increasing to a maximum of 33.2nmol/min/mg of protein at day 7, then decreasing to one third of the maximum value on day 12. Chlorophyll levels in a constant weight of tissue increased 260-fold over the period of 4 to 11 days. The changes in the level of acetyl-CoA carboxylase activity paralleled changes in fatty acid levels in tissue along the length of the 9-day-old maize leaf. The levels of both biochemical parameters increased in the region from the leaf base to 15mm along the leaf. After which they both decreased to a minimum at 25-30mm along the leaf before increasing to a maximum at 60mm along the leaf, and finally decreasing towards the leaf tip. A 5-fold increase in acetyl-CoA carboxylase activity was observed from the least favourable chloroplast stromal concentrations of ATP, ADP, Mg2+ and tt+ in the dark, to the most favourable concentrations of these metabolites present in the chloroplast stroma during light periods. These findings are consistent with, 1). a role for acetyl-CoA carboxylase in the regulation of fatty acid synthesis in maize photosynthetic tissue and, 2). control of acetyl-CoA carboxylase activity via light-dependent changes in the pH and concentrations of ATP, ADP and Mg2+ found in the stroma of chloroplasts. Several attempts were made to purify acetyl-CoA carboxylase using avidin-affinity chromatography. However, after the initial, apparently successful attempt, active enzyme could not be recovered from the avidin-affinity column upon elution with biotin. Changes were made to several chromatographic conditions, and although ionic strength in the range of 0.1 to l.0M KCl, did not affect the elution of active acetyl CoA carboxylase from the column; lowering the column flow rates from l.5ml/hr/ml of gel to 0.15-0.3ml/hr/ml of gel did appear to enhance the binding of the enzyme to the column. Using this flow rate, a 62 000 dalton protein and a 54 500 dalton protein were eluted in a fraction found to contain biotin-containing proteins. Since it is feasible that the 62 000 dalton is biotin-containing and since this protein has a similar molecular weight to 60 000-62 000 dalton biotin-containing subunit of maize leaf acetyl-CoA carboxylase, the potential for purifying acetyl-CoA carboxylase from maize leaves using avidin-affinity chromatography seems to exist. However, further investigation is necessary in order to facilitate the recovery of active carboxylase from the avidin-affinity column

Some contributions to the theory and application of polynomial approximation

The fundamental theorem, as far as this work is concerned, is Weierstrass' theorem (1885) on the approximability of continuous functions by polynomials. Since the time of Weierstrass (1815-97) and his equally important contemporary Chebyshev (1821-94), the topic of approximation has grown enormously into a subject of considerable interest to both pure and applied mathematicians. The subject matter of this thesis, being exclusively concerned with polynomial approximations to a single-valued, function of one real variable, is on the side of 'applied' side of approximation theory. The first chapter lists the definitions and theorems required subsequently. Chapter is devoted to estimates for the maximum error in minimax polynomial approximations. Extensions of this are used to obtain crude error estimates for cubic spline approximations. The following chapter extends the minimax results to deal also with best L[sub]p polynomial approximations, which include beat least squares (L₂) and best modulus of integral (L₁) approximations as special cases. Chapter 4 is different in character. It is on the practical problem of approximating to convex or nearly convex data

Global gene expression analysis of apple fruit development from the floral bud to ripe fruit

<p>Abstract</p> <p>Background</p> <p>Apple fruit develop over a period of 150 days from anthesis to fully ripe. An array representing approximately 13000 genes (15726 oligonucleotides of 45–55 bases) designed from apple ESTs has been used to study gene expression over eight time points during fruit development. This analysis of gene expression lays the groundwork for a molecular understanding of fruit growth and development in apple.</p> <p>Results</p> <p>Using ANOVA analysis of the microarray data, 1955 genes showed significant changes in expression over this time course. Expression of genes is coordinated with four major patterns of expression observed: high in floral buds; high during cell division; high when starch levels and cell expansion rates peak; and high during ripening. Functional analysis associated cell cycle genes with early fruit development and three core cell cycle genes are significantly up-regulated in the early stages of fruit development. Starch metabolic genes were associated with changes in starch levels during fruit development. Comparison with microarrays of ethylene-treated apple fruit identified a group of ethylene induced genes also induced in normal fruit ripening. Comparison with fruit development microarrays in tomato has been used to identify 16 genes for which expression patterns are similar in apple and tomato and these genes may play fundamental roles in fruit development. The early phase of cell division and tissue specification that occurs in the first 35 days after pollination has been associated with up-regulation of a cluster of genes that includes core cell cycle genes.</p> <p>Conclusion</p> <p>Gene expression in apple fruit is coordinated with specific developmental stages. The array results are reproducible and comparisons with experiments in other species has been used to identify genes that may play a fundamental role in fruit development.</p

Fruit crops: a summary of research, 1998

Pesticide deposition in orchards: effects of pesticide type, tree canopy, timing, cultivar, and leaf type / Franklin R. Hall, Jane A. Cooper, and David C. Ferree -- The influence of a synthetic foraging attractant, Bee-Scent™, on the number of honey bees visiting apple blossoms and on subsequent fruit production / James E. Tew and David C. Ferree -- The reliability of three traps vs. a single trap for determining population levels of codling moth in commercial northern Ohio apple orchards / Ted W. Gastier -- Evaluation of an empirical model for predicting sooty blotch and flyspeck of apples in Ohio / Michael A. Ellis, Laurence V. Madden, and L. Lee Wilson -- Influence of pesticides and water stress on photosynthesis and transpiration of apple / David C. Ferree, Franklin R. Hall, Charles R. Krause, Bruce R. Roberts, and Ross D. Brazee -- Influence of temporary bending and heading on branch development and flowering of vigorous young apple trees / David C. Ferree and John C. Schmid -- The effect of apple fruit bruising on total returns / Richard C. Funt, Ewen A. Cameron, and Nigel H. Banks -- Yield, berry quality, and economics of mechanical berry harvest in Ohio / Richard C. Funt, Thomas E. Wall, and Joseph C. Scheerens -- Monitoring flower thrips activities in strawberry fields at two Ohio locations / Roger N. Williams, M. Sean Ellis, Dan S. Fickle, and Carl M. Pelland -- Cluster thinning effects on fruit weight, juice quality, and fruit skin characteristics in 'Reliance' grapes / Yu Gao and Garth A. Cahoon -- Effects of various fungicide programs on powdery mildew control, percent berry sugar, yield, and vine vigor of 'Concord' grapes in Ohio / Michael A. Ellis, Laurence V. Madden, L. Lee Wilson, and Gregory R. Johns -- Influence of growth regulators, cropping, and number on replacement trunks of winter-injured 'Vidal Blanc' grapes / David C. Ferree, David M. Scurlock, and Rick Evans -- Effect of new herbicides on tissue-cultured black raspberry plants / Richard C. Funt, Thomas E. Wall, and B. Dale Stokes -- Investigating the relationship between vine vigor and berry set of field-grown 'Seyval Blanc' grapevines / Steven J. McArtney and David C. Ferree -- Summary of Ohio Fruit Growers Society apple cider competition, 1993-1997 / Winston Bash and Diane Mille

Transcriptome profile analysis of flowering molecular processes of early flowering trifoliate orange mutant and the wild-type [Poncirus trifoliata (L.) Raf.] by massively parallel signature sequencing

<p>Abstract</p> <p>Background</p> <p>After several years in the juvenile phase, trees undergo flowering transition to become mature (florally competent) trees. This transition depends on the balanced expression of a complex network of genes that is regulated by both endogenous and environmental factors. However, relatively little is known about the molecular processes regulating flowering transition in woody plants compared with herbaceous plants.</p> <p>Results</p> <p>Comparative transcript profiling of spring shoots after self-pruning was performed on a spontaneously early flowering trifoliate orange mutant (precocious trifoliate orange, <it>Poncirus trifoliata</it>) with a short juvenile phase and the wild-type (WT) tree by using massively parallel signature sequencing (MPSS). A total of 16,564,500 and 16,235,952 high quality reads were obtained for the WT and the mutant (MT), respectively. Interpretation of the MPSS signatures revealed that the total number of transcribed genes in the MT (31,468) was larger than in the WT (29,864), suggesting that newly initiated transcription occurs in the MT. Further comparison of the transcripts revealed that 2735 genes had more than twofold expression difference in the MT compared with the WT. In addition, we identified 110 citrus flowering-time genes homologous with known elements of flowering-time pathways through sequencing and bioinformatics analysis. These genes are highly conserved in citrus and other species, suggesting that the functions of the related proteins in controlling reproductive development may be conserved as well.</p> <p>Conclusion</p> <p>Our results provide a foundation for comparative gene expression studies between WT and precocious trifoliate orange. Additionally, a number of candidate genes required for the early flowering process of precocious trifoliate orange were identified. These results provide new insight into the molecular processes regulating flowering time in citrus.</p