Showing papers by "Macquarie University published in 1973"
TL;DR: The arrangement of lipid molecules in biological membranes enables them to play both a structural part in providing a matrix for membrane proteins and a functional one, in which they act as a barrier to the free flow of solutes.
Abstract: THE arrangement of lipid molecules in biological membranes enables them to play both a structural part in providing a matrix for membrane proteins and a functional one, in which they act as a barrier to the free flow of solutes1. These roles are usually fulfilled by phospholipids arranged in a flat bilayer with the hydrophobic segments of the molecules orientated towards the interior of the bilayer. The importance of this orientation is recognized in studies of model lipid membranes. Much of the knowledge of membrane lipid function has come from work with aqueous dispersions of liposomes, or microscopic phospholipid particles, in which the molecular arrangement is similar to the orientation found in biological structures2.
308 citations
TL;DR: The velocity of enzyme catalysed reactions increases with increasing temperature and the relationship between the velocity of reaction and temperature can be expressed either as the activation energy (E) or the temperature coefficient (Q10).
Abstract: Temperature-mediated changes in the kinetics of enzyme catalysed reactions can be due to effects on a number of different parameters. If the change in temperature does not (a) inactivate the enzyme, (b) alter the affinity of the enzyme for the substrate, an activator or an inhibitor or (c) alter the pH function of the reaction components, the velocity of enzyme catalysed reactions increases with increasing temperature. The relationship between the velocity of reaction and temperature can be expressed either as the activation energy (E) or the temperature coefficient (Q10). Both expressions can be derived from the empirical Arrhenius equation relating the velocity of reaction and temperature
$$\frac{\alpha \ln k}{\alpha T}=\frac{E}{R{{T}^{2}}}$$
(1)
where k is the reaction velocity constant, R the gas constant, T the absolute temperature and E a constant, subsequently called the activation energy (also written as A or μ.). Integration of equation (1) gives
$$\ln \frac{{{k}_{2}}}{{{k}_{1}}}=\frac{E}{R}\left( \frac{1}{{{T}_{1}}}-\frac{1}{{{T}_{2}}} \right)$$
(2)
from which it can be seen that the value for E can be obtained from the slope of the straight line when logk is plotted against 1/T
$$E=2\cdot 303R\times slope$$
$$\therefore E=4\cdot 576\times slope \left( where R=1\cdot 987 cal/mole/{}^{\circ }K \right)$$
297 citations
TL;DR: Exposure of male C.F.S. rats to novel apparatus raised plasma corticosterone levels, but the effect habituated, and the role of psychological component in psychosomatic stress and possible neuroendocrine pathways in psychological stress were discussed.
192 citations
TL;DR: A comparison was made of the differing ability of hearts, isolated from homeothermic and poikilothermic animals, to maintain beating at low temperature, and differences were observed between the activation energy (or temperature coefficient Q 10 ) for each type of heart.
Abstract: 1. 1. A comparison was made of the differing ability of hearts, isolated from homeothermic and poikilothermic animals, to maintain beating at low temperature. Over the temperature range (0–37°C) differences were observed between the activation energy (or temperature coefficient Q 10 ) for each type of heart. 2. 2. The activation energy for beat rate of the homeothermic heart dramatically increased below approximately 21·0°C. The heart beat of a poikilothermic animal maintained a constant activation energy over the full temperature range 0–37°C. 3. 3. The change in heart beat at 21°C for the homeotherm can be correlated with both temperature-induced phase changes in the lipid components of membranes, and the change in the activation energy of membrane-associated ATPases. None of these changes were observed in the membranes of the heart of the poikilotherm.
99 citations
TL;DR: The increased activation energies below approximately 12 °C, with consequent decreased rates of reaction for the photoreduction of NADP +, would result in impaired photosynthetic activity at chilling temperatures, which could explain the changes in chloroplast structure and function when chilling-sensitive plants are exposed to chilling temperatures.
85 citations
57 citations
TL;DR: Norfolk and Philip islands on the Norfolk Ridge linking New Caledonia and New Zealand are deeply weathered erosional remnants of volcanoes consisting of olivine basalt lavas and tuff as discussed by the authors.
Abstract: Norfolk and Philip Islands on the Norfolk Ridge linking New Caledonia and New Zealand are deeply weathered erosional remnants of volcanoes consisting of olivine basalt lavas and tuff. Both volcanoes were active in the late Pliocene. The subaerial portion of the Norfolk volcano was constructed during several volcanic episodes from about 3.05 m.y. to about 2.3 m.y. ago. Both were built when relative sea level stood at about its present level, indicating that the Norfolk Ridge has been very stable at this latitude for the past 3 m.y.
55 citations
TL;DR: Fractionation of E. gracilis DNA on CsCl gradients and subsequent hybridization experiments, as well as melting curves of DNA-RNA hybrids, show that chloroplast rRNA does not anneal specifically with either the cistrons for cytoplasmic rRNA or any DNA in the dark-grown cell, in contrast to those results found in some higher plants.
41 citations
TL;DR: The authors explored the nature of directional experience and directional behavior in countries with different scripts, children and adults in the United States and in Israel were asked to copy a number of geometric shapes, and the paths or sequences of strokes displayed some common developmental trends together with some specific differences stemming from the patterns taught for forming letters.
Abstract: To explore the nature of directional experience and directional behavior in countries with different scripts, children and adults in the United States and in Israel were asked to copy a number of geometric shapes. The paths or sequences of strokes displayed some common developmental trends together with some specific differences stemming from the patterns taught for forming letters. Generalization from letter patterns, however, followed a nonlinear course: strongest at the time when writing is first being mastered and then declining. A similar course, it is suggested, may occur in generalizations among other cognitive or perceptual behaviors.
41 citations
TL;DR: In this article, the effects of varying the inter-meal interval were studied in two food-deprived rats and it was found that water intake per session decreased, whereas amount drunk per interval increased, reaching a maximum at 4 min., before decreasing at 5 min.
Abstract: Schedule-induced polydipsia was studied in 2 food-deprived rats. In one condition one food pellet was presented per “meal,” and effects of varying the inter-meal interval were studied. It was found that as inter-meal interval increased, water intake per session decreased, whereas amount drunk per interval increased, reaching a maximum at 4 min., before decreasing at 5 min. In a second condition rate of food consumption was held constant by increasing meal size as inter-meal interval increased. Despite holding consummatory rate constant, as inter-meal interval increased, the amount drunk per session again decreased. These results are incompatible with the suggestion that schedule-induced polydipsia is a function of consummatory rate.
36 citations
TL;DR: A polarimetric study of a 36-residue peptide, α1CB2, obtained by CNBr cleavage of rat-tail tendon collagen, and the marked difference in thermal stability is interpreted in terms of the differing degree of hydroxylation of proline residues in otherwise identical peptides.
TL;DR: In this paper, the authors assess the applicability of the Gottschalk-Gleser Content Analysis Scales in Australia using verbal behaviour from 32 successful students and 35 hospitalized psychiatric patients.
Abstract: Samples of verbal behaviour were collected from 32 successful students and 35 hospitalized psychiatric patients in order to assess the applicability of the Gottschalk-Gleser Content Analysis Scales in Australia. Estimates of interjudge reliability and criterion groups validity resulted in acceptable findings for the Anxiety and Schizophrenic scales, and for the indices of hostility with the exception of Hostility Outward. Discriminant validity of the scales was successfully demonstrated for the student sample only. Comparisons of the data with American norms yielded significantly higher Hostility Inward scores for both Australian samples.
TL;DR: Deep sea drilling in the eastern Indian Ocean shows that the oceanic crust off Western Australia is approximately 140 million years old and becomes younger to the west; this dates the initial opening of the Indian Ocean.
Abstract: Deep sea drilling in the eastern Indian Ocean shows that the oceanic crust off Western Australia is approximately 140 million years old and becomes younger to the west; this dates the initial opening of the Indian Ocean.
TL;DR: It is concluded that pigment is added on to the pre-existing proteins of the etioplast to stabilise it during extraction rather than the activity of PS II (Photosystem II).
TL;DR: In this article, a sample of 92 landslides from the greywacke hill country of the North Island of New Zealand is classified on the basis of as many as 19 numerical and 43 disordered multistate attributes.
TL;DR: The temperature at which the changes occurred did not correlate with the susceptibility of the cultivars to low temperature breakdown, and the apparent energy of activation of both respiration and motion of the spin label increased abruptly at low temperatures indicative of a temperature-induced phase change in the membrane lipids.
Abstract: Mitochondria were isolated from fruit of six cultivars of apples differing in susceptibility to the physiological disorder, low temperature breakdown. The state 3 rate of succinate-dependent oxygen uptake and the motion of a spin label were measured at from 0 to 25 C. Arrhenius plots of the data showed that the apparent energy of activation of both respiration and motion of the spin label increased abruptly at low temperatures indicative of a temperature-induced phase change in the membrane lipids. The changes were detected with mitochondria from all of the cultivars, but the temperature at which the changes occurred did not correlate with the susceptibility of the cultivars to low temperature breakdown.
TL;DR: The correlation between the improvement in behavioral performance and the recovery of endogenous NA to control values suggests that the supposition implicating NA in the development of avoidance learning is a phenomenon worthy of further investigation.
Abstract: Publisher Summary This chapter focuses on the implication of noradrenaline in avoidance learning in the rat The anatomical and physiological consequences of olfactory deafferentation are profound: (1) degeneration occurs in primary olfactory neurones passing to the allocortex; (2) following primary neurone degeneration, transneuronal degeneration occurs involving the pyramidal cells of the allocortex, which is characterized in the rat by a lack of dendritic proliferation; and (3) following unilateral section of an olfactory tract, a reduction in telencephalic noradrenaline (NA) occurs in the side ipsilateral to the lesion, with no concomitant significant reduction in hypothalamic NA The correlation between the improvement in behavioral performance and the recovery of endogenous NA to control values suggests that the supposition implicating NA in the development of avoidance learning is a phenomenon worthy of further investigation It is also suggested that the results as presented offer a tentative explanation for the mode of action of amitriptyline in the clinical situation
TL;DR: In this paper, a 2-benzimidazolemethanol was obtained by methanesulfonylation of 4 pyridine at 0°, and α-[1-(methylsulfonyl)-2-(chloromethyl)-2.
TL;DR: The homology functor from the category of free abelian chain complexes and homotopy classes of maps to that of graded groups is full and replete (surjective on objects up to isomorphism) and reflects isomorphisms as mentioned in this paper.
Abstract: The homology functor from the category of free abelian chain complexes and homotopy classes of maps to that of graded abelian groups is full and replete (surjective on objects up to isomorphism) and reflects isomorphisms. Thus such a complex is determined to within homotopy equivalence (although not a unique homotopy equivalence) by its homology. The homotopy classes of maps between two such complexes should therefore be expressible in terms of the homology groups, and such an expression is in fact provided by the Kunneth formula for Hom, sometimes called ‘the homotopy classification theorem’.
01 Dec 1973
TL;DR: In this paper, the oxygen fugacities of the individual lava flows appear to be principally a function of temperature and intrinsic chemical equilibria existing at the time of formation of the basaltic liquid.
Abstract: Alkali basaltic rocks from the Southern Highlands, N.S.W., contain oxide phases of both high and low pressure origin. The two phases are readily distinguished using chemical and textural criteria. Chemical data for low‐pressure Fe‐Ti oxides indicate that oxygen fugacities of the host lavas range from 10‐12.8 to 10‐8 atm at 950° to 1110°C. In most cases, the oxygen fugacities of the individual lava flows appear to be principally a function of temperature and intrinsic chemical equilibria existing at the time of formation of the basaltic liquid. However, some relatively differentiated flows shows a high degree of oxidation due to volatile enrichment with fractionation. Rare glassy flows show dendritic crystallization of Fe‐Ti oxides. Most flows in which abundant olivine was the first phase to be precipitated also contain Cr‐rich spinels associated, and apparently coeval, with the earliest‐crystallizing olivine.
TL;DR: Comparative electrophoretic data collected for seven proteins from thirty-four species of marsupial have been examined to define the advantages and shortcomings of electrophoresis as a taxonomic method.
TL;DR: The sedimentary history of Australia suggests that Cretaceous transgressions occurred as a result of displacement of ocean water by elevated spreading ridges and of subsidence of continental interiors near subduction zones as discussed by the authors.
Abstract: The sedimentary history of Australia suggests that Cretaceous transgressions occurred as a result of displacement of ocean water by elevated spreading ridges and of subsidence of continental interiors near subduction zones.
TL;DR: The potential of one model—the Markov Chain—which is capable of predicting enrolments for an education system is examined, and the projected enrolments compared to the actual enrolments in those years are compared.
Abstract: Mathematical models can assist educators in the preparation of their educational plans and their potential in this regard is being increasingly realized. As a result, models have found application at all levels at which planning is conducted. This paper examines the potential of one model—the Markov Chain—which is capable of predicting enrolments for an education system. The model is applied to the New South Wales State Government education system between 1947 and 1961 and the projected enrolments compared to the actual enrolments in those years. Some success is achieved but it appears as if the data rather than the model are responsible for this. The limitations of the Markov Chain approach are discussed and present research and directions listed.
TL;DR: The inhibition of initial state 3 rates was satisfactorily relieved by incubating the mitochondria with substrate, and several cycles of ADP under conditions which increased the absolute rate of respiration.
Abstract: The initial state 3 rates of respiration of mitochondria from plant tissue and from rat liver are usually less than the state 3 rates obtained after the mitochondria experience several state 3-state 4 cycles.
TL;DR: In this article, the effect of the assumption of equal diffusivities on the Bowen ratio was examined in relation to stability conditions, and some recently published experimental relations between the eddy Diffusivities for momentum, heat and water vapour were then used to determine the effect.
TL;DR: It is concluded that the inhibition of photochemical activity caused by filipin is a secondary effect resulting from a change in membrane conformation induced by the antibiotic.