Structural studies of a fucogalactoxyloglucan from pinus radiata primary cell walls : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Biochemistry at Massey University

1. The changes in carbohydrate composition of elongating Pinus radiata primary cell walls were investigated. In the hemicellulose B extracts, a large increase in the percentage of non-starch, non-cellulosic, glucose was found to occur on cessation of cell-wall elongation. 2. By fractionation of the hemicellulose B extracts, with a variety of methods involving precipitation from an aqueous solution, a xyloglucan was purified. This xyloglucan was the major hemicellulose of the Pinus radiata hypocotyl cell wall. 3. Characterisation studies on the xyloglucan involved: quantitative analysis of the monosaccharides derived by nitric acid/urea hydrolysis; identification of the partial hydrolysis products derived by trifluoroacetic acid hydrolysis; quantitation of the sugar linkages using methylation by the Hakomori method; and analysis of the anomeric configuration of component sugars using chromium trioxide oxidation. 4. From the results a tentative structure has been suggested for the xyloglucan, consisting of a backbone of B-D-gluco-pyranose residues linked together by 1-4 glycosidic bonds, and with sidechains of single xylose residues linked through C-6 of the glucose units. Galacto and fuco-1,2- galacto sidechains are attached to some of the xylose residues, probably through the C-2 of the xylose

Cyclic nucleotide-gated channels: structural basis of ligand efficacy and allosteric modulation

Most working proteins, including metabolic enzymes, transcription regulators, and membrane receptors, transporters, and ion channels, share the property of allosteric coupling. The term 'allosteric' means that these proteins mediate indirect interactions between sites that are physically separated on the protein. In the example of ligand-gated ion channels, the binding of a suitable ligand elicits local conformational changes at the binding site, which are coupled to further conformational changes in regions distant from the binding site. The physical motions finally arrive at the site of biological activity: the ion-permeating pore. The conformational changes that lead from the ligand binding to the actual opening of the pore comprise 'gating'. In 1956, del Castillo and Katz suggested that the competition between different ligands at nicotinic acetylcholine receptors (nAChRs) could be explained by formation of an intermediate, ligand-bound, yet inactive state of the receptor, which separates the active state of the receptor from the initial binding of the ligand (del Castillo & Katz, 1957). This 'binding-then-gating', two-step model went beyond the then-prevailing drug-receptor model that assumes a single bimolecular binding reaction, and paralleled Stephenson's conceptual dichotomy of 'affinity' and 'efficacy' (Stephenson, 1956). In 1965 Monod, Wyman and Changeux presented a simple allosteric model (the MWC model) (Monod et al. 1965) that explained the cooperative binding of oxygen to haemoglobin; it was adopted as an important paradigm for ligand-gated channels soon after its initial formulation (Changeux et al. 1967; Karlin, 1967; Colquhoun, 1973)

Do Frictions Matter in the Labor Market? Accessions, Separations and Minimum Wage Effects

We measure labor market frictions using a strategy that bridges design-based and structural approaches: estimating an equilibrium search model using reduced-form minimum wage elasticities identified from border discontinuities and fitted with Bayesian and LIML methods. We begin by providing the first test of U.S. minimum wage effects on labor market flows and find negative effects on employment flows, but not levels. Separations and accessions fall among restaurants and teens, especially those with low tenure. Our estimated parameters of a search model with wage posting and heterogeneous workers and firms imply that frictions help explain minimum wage effects.minimum wage, labor market flows, monopsony, Bayesian estimation

The literary criticism of TS Eliot

Thesis (M.A.)--Boston University, 1942. This item was digitized by the Internet Archive

Relationship between change in condition of beef cows during the pasture season and performance of their calves to weaning

One hundred and fifty-five Angus cows were measured ultrasonically for fat thickness using a Branson Model 12 Sonoray and visually scored for condition in April and October of 1966. Least-squares analyses of the data collected were conducted, using as a dependent variable in each analysis one of the three calf traits observed and recorded at weaning, viz., average daily gain, type score and condition score. The inde-pendent variables included in the model were age of dam, sex of calf, change in dam\u27s fat thickness, squared change in dam\u27s fat thickness, and age of calf. Change in fat thickness, as well as the squared change in dam\u27s fat thickness, significantly affected weaning condition score but not weaning gain or weaning type score. The same analyses were conducted with change in dam\u27s condition score substituted for change in fat thick-ness. Although cow condition score was highly correlated with each of the two ultrasonic estimates of fat thickness (r = 0.70 and 0.67 in spring and fall data, respectively), change in cow condition score did not affect weaning average daily gain, type or condition score of calf. A proposed explanation is that cow condition score may be influenced by cow size such that variation in condition score did not reflect dif-ferences in fatness as accurately as did the variation in ultrasonically measured fat thickness. The findings suggest that, under conditions similar to those in this study, change in fat thickness of the dam in conjunction with a measure of calf fatness might be useful in partitioning increases in calf weight into gain due to growth and gain due to fattening

Major Campbell Wallace: Southern railroad leader

Major Campbell Wallace distinguished himself as a railroad leader in Tennessee and Georgia during the middle years of the nineteenth century. From 1853 until 1963 he occupied the presidency of the East Tennessee and Georgia Railroad Company and from 1866 until 1868 was superintendent of the Western and Atlantic Railroad. During his years on the East Tennessee and Georgia, he was able to place that road on a firm financial basis, as well as to direct efficiently the expansion of that road. In Georgia, under effective administration, the war-devastated Western and Atlantic were restored to first class operating condition; furthermore, the line paid many of its debts. During his three terms (1879-1890) on the Georgia Railroad Commission, Wallace was active defending individual rights over corporate rights; moreover, he was a guiding hand in the organization and construction of two Alabama railroads. Thus, the basic purpose of this study is to determine the influence of Major Wallace in the development of railroad enterprise throughout the South in the nineteenth century. In assessing Wallace\u27s achievement, the majority of material was taken from the Campbell Wallace Papers in Special Collections in the University of Tennessee Library, which is the only primary source that covers his entire life. Of course, additional primary sources such as newspapers, census returns, and legislative journals were consulted. The writer is fully aware that many of these sources are not very reliable; however, since they are the only ones available, it has been necessary to utilize them. Several of the sources, especially the Atlanta Constitution, are rather eulogistic in their descriptions of Wallace\u27s activities; thus, the writer has experienced real difficulty in attempting to present a critical study. Yet, when possible, more dependable materials such as the Acts of Tennessee, census returns, and the official reports of the various railroads were consulted

A Matrix Application to Systems of n Linear and Non-Linear Homogenous 1st Order Differential Equations

In recent years, matrices have become very useful in the study of differential equations. The aim of this paper is to demonstrate the application of matrices to the existence and uniqueness of solutions to systems of differential equations. This matrix theory will be applied to both the linear and non-linear homogeneous 1st order cases

Preweaning body measurements of beef calves and traits of their dams as predictors of calves\u27 postweaning and lifetime performance

Body measurements, body composition traits and certain performance traits of 74 Angus bull and 84 Angus heifer calves, recorded at three different observations up to weaning, were studied to assess their value as predictors of postweaning ADG, lifetime ADG (ADG from birth until the end of test), final condition scope and fat thickness (measured ultrasonically when the postweaning feeding period was terminated). n These calves were born from January 17, 1968, to April 26, 1968. A stepwise regression procedure was employed to construct prediction equations. Traits that could enter the regression equation as independent variables included heart girth, back length, loin length, rump length, total length, type score, condition score, weight and age. Also, fat thickness measured ultrasonically over the twelfth and thirteenth ribs at weaning was considered among the independent variables. Coefficients of multiple determination (R2) for the equations to predict the dependent variables tended to be larger when the independent variables were the calves\u27 weaning traits rather than preweaning or interim traits. It was concluded that if the dependent variables are to be predicted from calf traits observed at only one time of observation, that observation should be taken at an average age of about 220 to 225 days (weaning). Various combinations of the weaning body measurements and body composition traits explained significantly (P \u3c .05) more variation in postweaning ADG, lifetime ADG, final condition score and final fat thickness than was explained by weight and age alone. For bulls, the increases in R2 were 0.239, 0.113, 0.155, and 0.207, respectively, for the dependent variables enumerated above. In the case of heifers, the increases in R2 were 0.277, 0.089, 0.105, and 0.1A6, respectively. Hence, it appears from these results that body dimension measurements and estimates of fatness can be used effectively to improve the predict tion of calf performance and subsequent body composition over conventional methods utilizing only calf weight and age. The addition of traits of the dam (weight and condition score and linear, squared and cubed forms of change in weight and condition of the dam from April, 1968, until time of observation of calf) to the regression equations, after entering the calf traits, generally did not result in significant increases in the R2 values for predicting postweaning and lifetime ADG. These cow variables tended to be slightly more important as predictors of final condition score and fat thickness of the calves. It is doubtful that the additional precision in predicting future performance and body composition of calves obtained by considering these traits of the dams, is large enough to warrant the extra effort and expense necessary to obtain these data

An investigation of the heat rejection to the engine oil in an internal combustion engine.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1944.MICROFICHE COPY AVAILABLE IN BARKER ENGINEERING LIBRARY. MIT copy bound with: Analysis of an automatic pressure controller / by Lawrence S. Churchill [1944]Includes bibliographical references (leaf 29).B.S