Showing papers by "University of Western Australia published in 1971"

Control of leghaemoglobin synthesis in snake beans.

Abstract: 1. The finding that the plant is the genetic determinant of leghaemoglobin production in legume nodules was further tested by inoculating snake beans with two strains of Rhizobium selected to give large genetic differences. Carbohydrate requirement patterns, immunological techniques and DNA base ratio determinations were used to demonstrate genetic differences between the two rhizobial strains. 2. Partially purified preparations of the haemoglobins from the nodules produced by the two strains showed no differences when examined by electrophoresis, isoelectric focusing or ion-exchange chromatography. 3. Two different leghaemoglobins from each type of nodule were separated by chromatography on DEAE-cellulose. One of these was isolated in the Fe 3+ form and accounted for two-thirds of the total leghaemoglobin. When it was examined in the analytical ultracentrifuge and by amino acid analysis, this major component did not vary with the inoculant rhizobial strain. The molecule had an s 20,w of 1.88S, a diffusion coefficient of 10.7×10 -7 cm 2 · s -1 and a mol. wt. of 16700. 4. These results strongly support the hypothesis that the mRNA for leghaemoglobin is transcribed from plant DNA.

Gel chromatography of humic acid

Abstract: Summary Gel-solute interactions have been reported in the application of gel chromatography to humic acid. The origins and nature of these interactions are discussed with particular reference to the behaviour of ‘Sephadex’ with compounds which are aromatic, heterocyclic, phenolic, or charged. Such structural units are known to be present in humic acid and could account for its observed interactions with ‘Sephadex’gel. The behaviour of humic acid on ‘Sephadex’and a number of other gel materials in a variety of eluants is examined. The observed deviations of these systems from that of an ideal gel chromatography system are explained in terms of charge and adsorption effects. The results indicate that a fractionation based solely on molecular weight differences can be achieved by using an alkaline buffer containing a large ammo cation as eluant together with ‘Bio-gel’, ‘Sephadex’ or an agar based gel. Systems in which gel-solute interactions occur should not be used for molecular weight fractionations.

The common septoria diseases of wheat

Abstract: Introduction -231 Economic importance -232 Stage of plant development for infection 236 Taxonomy and nomenclature -237 Symptomatology and pathological history -239 Life cycle -241 Factors affecting infection and symptom expression -243 Humidity, temperature, and light -244 Spore load -245 Plant nutrition 245 Plant age 246 Interaction with other diseases -246 Host range and pathogenic specialization -247 Host resistance and genetics of resistance -249 Co trol250 Resistant varieties -250 Seed treatments -251 Cultural practices -252 Cover spraying -253 Quarantine -253 Summary -253 Acknowledgments -254 Literature Cited -254

Optimal Curve Fitting With Piecewise Linear Functions

Abstract: A method is described for determining an optimal straight-line segment approximation to specified functions for constrained and unconstrained endpoints.

New crystallographic shear families derived from the rutile structure, and the possibility of continuous ordered solid solution

Abstract: A number of new families of titanium and mixed titanium plus chromium oxides has been discovered, their structures all being derived from the rutile type by crystallographic shear. Different famili...

The Death of Alexander the Great: Rumour and Propaganda

Abstract: Propaganda and history are often inseparable. Most governments are in a position to control the dissemination of evidence, and if an event is embarrassing or damaging, the relevant evidence is certain to be distorted or withheld. Moreover the writers of history, however innocent their motives, cannot disregard the official apologia of their rulers. One notes with interest that the learned authors of the official Soviet history of the world portray the invasion of eastern Poland on 17 September 1939 as a crusade of liberation. Of course it might be true that the people liberated by the Red Army were glad to be rid of ‘the arbitrary despotism of the Polish Pans’ and that in the subsequent elections there was absolute freedom of choice and overwhelming support for union with the Ukraine, but the fact remains that it was impossible for membersof the Moscow Academy to contradict their government's justification of the invasion.

On the aggregation of wadsley defects in slightly reduced rutile

Abstract: Electron micrographs of a small proportion of specimens from a sample of slightly reduced rutile, TiO1·9986, show groups of parallel fringes that are interpreted as oxygen-deficient lamellae of CS planes parallel to {132}. Their spacing varies within a group, and with the number in the group, in a way that suggests the operation of both attractive and repulsive forces between CS planes.

The I.R. Spectra of Interlamellar Kaolinite-Amide Complexes—I. The Complexes of Formamide, N-Methyl-Formamide and Dimethylformamide

Abstract: The i.r. spectra of interlamellar kaolinite complexes with formamide, N-methylformamide and dimethylformamide have been examined. The spectra show that the amides hydrogen-bond, through the C=O group of the amide to the inner surface kaolinite hydroxyls and decrease the intensity of the kaolinite ν(OH) bands. Hydrogen-bonded kaolinite hydroxyl bands appear at lower frequencies and these have been correlated to the original kaolinite ν (OH) bands. Other kaolinite bands in the complexes show smaller perturbations of the kaolinite vibrations. Each amide hydrogen-bonds to different groups of hydroxyls. Formamide hydrogen-bonds to the 3690 and 3664 cm−1 hydroxyls, N-methylformamide to the 3690 and 3648 cm−1 hydroxyls. The interpretation for the dimethylformamide complex is less clear. The ν(NH) frequencies of formamide and N-methylformamide in the complexes are intermediate between that in dilute non-polar solution and in the liquid. This could arise from either or both a degree of intermolecular association of the amide when between the kaolinite lamellae, or to weak N—H … O hydrogen bonds to the tetrahedral oxygen sheet of the lamellae.

Growth and mortality in a field population of Amphibolurus lizards exposed to seasonal cold and aridity

Abstract: The demography of a discrete population of Amphibolurus ornatus lizards in Western Australia was studied over a period of four years. Large differences in the rate of growth of individuals from the same cohort were observed during each year of the study and each animal could be classified as maturing at one, two or three years of age. Fast- and slow growing individuals were shown to suffer differential mortality during seasonal stresses with fast growers being cold hardy and drought sensitive whereas slow-growers were cold sensitive but drought resistant. The potential longevity of fast- and slow-growing animals appears to be identical but the survival of animals in the field depends markedly upon the incidence of climatic extremes, slow growers tending to live longer than fast growers in the study area. Changes that were observed in the size and age structure of the breeding population during the period of study can be interpreted in terms of the weather conditions experienced by the population over this period. The significance of the variability in individual growth rates of Amphibolurus ornutus for the persistence of the study population is discussed.

Chemistry of Saline Soils and Their Physical Properties

Abstract: An outline of the forces involved in clay particle interaction (swelling and dispersion) is given as a background for the interpretation of the physical behaviour of sodic soils, especially in relation to electrolyte levels. The electrolyte concentration below which appreciable decreases in soil permeability are encountered has been termed the threshold concentration and this concentration increases with the degree of sodium saturation of the soil colloids. The application of the threshold concentration concept to the management and reclamation of sodic soil is discussed.

Distribution of alkaloids in some Western Australian plants

Abstract: Previous Australian phytochemical surveys for alkaloids (5, 7, 8) have been concerned mainly with plants that occur in the State of Queensland, and particular attention has been directed to those found in rain forest communities. Relatively little information is available concerning the occurrence of alkaloids in species that grow in the more temperate and arid regions of the continent. The present investigation was undertaken in an attempt to remedy this deficiency. By means of a simple field test, 1301 species representing 469 genera and 102 plant families that grow in the SouthWest and Eremean Vegetation Provinces of Western Australia (4) have now been examined for alkaloids. The plants investigated are mainly shrubs or herbs and the majority are native species, but some introduced and naturalized plants encountered in the field have also been included in the survey. Flowering plants were collected, and in all cases a voucher specimen has been lodged in the Western Australian Herbarium, Perth. The date of collection and precise details of the locality at which the species was found have been recorded on the herbarium sheets. Plants were collected during the day and packed loosely in plastic bags until the evening. A representative sample (ca. 5 g) of the tops of shrubs, or of whole herbs, was then chopped finely with secateurs and just covered with 1% HCl. The mixture was shaken vigorously, allowed to stand overnight, then filtered. The extract was tested with Mayer's reagent, which had been prepared by the addition of a solution of KI (100 g) in water (200 ml) to a solution of HgCl2 (27.2 g) in water (1200 ml) fol-

The compression block technique.

Abstract: Two points were made in support of the compression-block technique as a useful tool in motor-control research. The effect of motor impairment (if any) can be controlled (a) by only making direct comparisons between results obtained under block, and (b) by keeping muscle exertion during the entire course of the block to an absolute minimum to avoid muscle fatigue.

Philip II and Upper Macedonia

Abstract: One of the most enigmatic figures in Macedonian history is Alexander of Lyncestis, son of Aeropus and son-in-law of the great Antipater. During the reign of his royal namesake he achieved sensational prominence, deposed from his command of the elite Thessalian cavalry under suspicion of treasonable correspondence with the Persian court. Still more sensational, however, is his involvement in the murder of Philip II. Our sources are unanimous that together with his brothers, Heromenes and Arrhabaeus, he was party to the murder, but secured pardon by his immediate recognition of Alexander as king.The immediate recognition is certain, the participation in the murder much less so.

Studies on the mechanism of interaction between rabbit transferrin and reticulocytes

Abstract: The two stages in the uptake of transferrin by rabbit reticulo-cytes were investigated using radioiodine-labeled rabbit transferrin and albumin. The first stage of rapid, temperature-insensitive uptake of transferrin was similar to albumin uptake: uptake of both proteins increased linearly with increasing protein concentration of the incubation medium up to at least 60 mg/ml, was maximal at low ionic strength and pH, and increased in the presence of basic polyamino acids. Transferrin uptake was in part dependent on the reticulocyte concentration of the blood, but albumin uptake was independent of reticulocyte concentration. The second slower, temperature-sensitive stage of transferrin uptake was linearly related to reticulocyte concentration, and was not found with albumin, α1-macroglobulin or γ-globulin. Transferrin uptake was optimal at physiological pH and ionic strength and was unaffected by basic polyamino acids. When the transferrin concentration was raised, uptake increased to reach a maximum at a concentration of 15 mg/ml. It was concluded that the first stage of transferrin uptake was in part or wholly due to non-specific adsorption of transferrin to erythrocytes, while the second stage of uptake was specific for transferrin and reticulocytes and depended upon normal function of the cells.

Kinetics of heterogeneous isotopic exchange reactions: derivation of an Elovich equation

Abstract: A derivation is presented for an Elovich equation, d θ /d t = A exp (– Bθ ), describing the kinetics of heterogeneous isotopic exchange reactions involving non-uniform surfaces of solids. By considering a small element of the surface, an equation was obtained relating the rate of transfer of isotope to the rate at which all the molecules of the exchanging species undergo exchange at that element; the effect on kinetics due to the development of excess isotope concentrations on more labile surface sites during isotopic exchange was taken into account. The Elovich equation for exchange over the whole surface was then obtained by an approximate integration procedure previously used in the kinetics of chemisorption of gases on solids, assuming that the activation energies for exchange were a linear function of θ . The term θ was related to the experimentally measured fraction exchange F by θ = bF/[ b + a (1 – F)] where a and b are the concentrations of the exchanging species in the system, in the adsorbed and free states respectively. The derivation indicates methods for obtaining concentration independent rate constants from the parameters A and B .