Showing papers by "James Cook University published in 1995"

Nuclear rDNA ITS sequence variation in the trematode genus Echinostoma : an aid to establishing relationships within the 37-collar-spine group

Abstract: The taxonomic history of members of the 37-collar-spine group within the genus Echinostoma has been very confused. We obtained DNA sequence data from the nuclear rDNA ITS1, 5.8S and ITS2 of 7 nominal species belonging to this group, Echinostoma trivolvis (Cert, 1914), E. revolutum (Frolich, 1802), E. caproni Richard, 1964, E. acaproni arasasingam et nl. 1952, E. paraelzsei Lie & Basch, 1967, two African isolates, E. sp.I and E. sp.II, and of one 28-collar-spined echinostome, E. holtense (,4sada, 1926). Five of the eight species n;ere clearly distinguishable using ITS data. Sequences from the remaining three tasa, E. cnpl olzi, E. sp.ll and E. liel mere identical to one another and the group containing these laxa was distant from other 3'7-collar-spine species on a phylogenetic tree. E. tvizrolzris and E. pavaensei form a second, but less distinct group within the 35-collar-spine group. The resolution obtained using DNA sequencing will assist in the current reclassification of the group. It also provides a model for future work on sibling species.

Factors controlling suspended sediment on inner-shelf coral reefs, Townsville, Australia

Abstract: This study was undertaken to describe the characteristics of suspended sediment concentrations (SSCs) of marine waters near inner-shelf fringing coral reefs and relate these to the prevailing oceanographic and meteorological conditions. Using logging optical backscatter nephelometers, SSCs were measured at fringing reefs at Magnetic Island and on the adjacent inner-shelf, Cleveland Bay, N.E. Australia. Continuous measure-ments were made over a period of 4 months, representing possibly the most comprehensive set of SSC data collected near coral reefs. Wind, current and wave data were also collected. Temporal and spatial variation in near-bed SSCs is high. Periods of strong southeasterly regional winds generate swells, which, within 1 km of the reefs, produce near-bed SSCs of well over 200 mg/l. At the fringing coral reefs at Arthur and Geoffrey Bays, SSCs were less than 5 mg/l for most of the time and rarely exceeded 40 mg/l, but there were a number of periods of over 24 h when near-bed SSCs continuously exceeded 20 mg/l. The height of locally produced, short-period wind-waves is the dominant control on the magnitude of near-bed SSCs at the reef sites, and thus the wind regime heavily influences conditions for coral communities. The magnitude of the tide is of lesser importance. However, it is likely that flushing of these bays by tidal currents is important in preventing a long-term build-up of SSC in the water around the coral reefs.

Designed Synthesis of Mononuclear Tris(heteroleptic) Ruthenium Complexes Containing Bidentate Polypyridyl Ligands

Abstract: A general synthetic methodology is reported for tris(bidentate)ruthenium(II) complexes containing three different polypyridyl ligands, based on the sequential addition of the ligands to the oligomer [Ru(CO)₂Cl₂](subscript n). The tris(heteroleptic) complexes were characterized by FAB mass spectrometry and NMR spectroscopy. An X-ray crystal structure determination was made for the complex, [Ru(Me₂bpy)(phen)(bpa)](PF₆)₂. C₆H₁₄·[C₄ₒH₄₃F₁₂N₇P₂Ru, M = 1062.8; Me(2)bpy = 4,4'-dimethyl-2,2'-bipyridine, phen = 1,10-phenanthroline, bpa = bis(2-pyridyl)amine]: triclinic, space group

Chapter 1: Text and Discourse in Education: An Introduction to Critical Discourse Analysis:

Abstract: If we take seriously lessons from the sociology of science, it would be unwise to interpret paradigm shifts in educational research in terms of the succession of disciplinary truths, the emergence of more refined and exacting methods, and a continually improving \"state of the art.\" To embrace such a view of research—a view that often guides annual reviews of research, overviews of the field, encyclopedias, handbooks, and so forth—would be to define educational research first and foremost as a positivist and empiricist enterprise. Like other kinds of \"official knowledge\" (Apple, 1993), educational research is mediated by a complex political economy that entails the immediate statements and imperatives of the institutions it serves; the politics of the academies, government funding agencies, and corporations where theory, research, and curriculum work is undertaken; and larger political and economic interests that influence what can be said, by whom, and in what terms across and within institutions. Of course, social sciences and educational studies do produce and circulate new knowledge, and researchers are able to assert varying kinds and degrees of agency in ascertaining and asserting what should count as educational research in local sites. But a broader social analysis is necessary to grasp how particular perspectives, methods, and \"truths\" are made available, selected, and framed for the work of education (Apple, 1985; Wexler, 1987). Since the Second World War, two major demographic and socioeconomic changes have placed issues of language, discourse, and difference on the educational agenda: the expanded recognition of the educational entitlements

A molecular phylogeny of the genus Echinococcus

Abstract: Three nucleotide data sets, two mitochondrial (COI and ND1) and one nuclear (ribosomal ITS1), have been investigated in order to resolve relationships among species and strains of the genus Echinococcus. The data have some unusual properties in that mitochondrial heteroplasmy was detected in one strain of E. granulosus, and more than one class of ITS1 sequence variant can occur in a single isolate. The data failed to support the hypothesis that E. granulosus, as it is currently viewed, is a single valid species. Rather, the strains of E. granulosus seem to comprise at least three evolutionarily diverse groups, the sheep strain group, bovine strain group and horse strain group. Molecular distances between them are comparable to, or greater than, molecular evolutionary distances observed between recognized species. The affinities of the cervid strain of E. granulosus are unclear because of ambiguous data, but this strain does not appear to be ancestral to others. E. multilocularis may not be distinct from E. granulosus. However, the remaining two species, E. vogeli and E. oligarthrus appear distinct and rather distant from the first two. Based on the results presented here, taxonomic revision of the genus is clearly warranted.

Physiological effects of undernutrition on postpartum anoestrus in cows.

Abstract: The focus of this review is the physiological effects of undernutrition on ovarian follicle growth and the occurrence of ovulation in postpartum cows. Evidence suggests that moderate levels of underfeeding, before or after calving, may interfere with the mechanism(s) of final follicle maturation and ovulation, whereas more pronounced nutritional deficiencies may affect the mechanism(s) regulating dominant follicle size and the dynamics of dominant follicle growth and regression. Severe undernutrition may result in the absence of follicles > 5 mm in diameter. These changes are consistent with likely effects of reduced LH or FSH secretion that have been associated with inhibition of both tonic and surge release of GnRH from the hypothalamus. As yet, there is no direct evidence for local effects of undernutrition on ovarian function in cows, and studies examining this tissue often ignore dynamic interdependencies between the hypothalamus, anterior pituitary gland, and the ovaries, and possible nutritional modulation of ovarian feedback mechanisms that affect gonadotrophin secretion. Further research is required to elucidate nutritional effects on the positive feedback regulation of gonadotrophin secretion and on the expression of behavioural oestrus. Further studies are also needed to determine whether nutritional or metabolic state may influence ovarian function directly in a manner that affects the duration of postpartum anoestrus and fertility in postpartum cows.

Adjustment of K' to varying pH and pMg for the creatine kinase, adenylate kinase and ATP hydrolysis equilibria permitting quantitative bioenergetic assessment.

Abstract: Physiologists and biochemists frequently ignore the importance of adjusting equilibrium constants to the ionic conditions of the cell prior to calculating a number of bioenergetic and kinetic parameters. The present study examines the effect of pH and free magnesium levels (free [Mg2+]) on the apparent equilibrium constants (K9) of creatine kinase (ATP: creatine N-phosphotransferase; EC 2.7.3.2), adenylate kinase (ATP:AMP phosphotransferase; EC 2.7.4.3) and adenosinetriphosphatase (ATP phosphohydrolase; EC 3.6.1.3) reactions. We show how K9 can be calculated using the equilibrium constant of a specified chemical reaction (Kref) and the appropriate acid-dissociation and Mg(2+)-binding constants at an ionic strength (I) of 0.25 mol l-1 and 38 degrees C. Substituting the experimentally determined intracellular pH and free [Mg2+] into the equation containing a known Kref and two variables, pH and free [Mg2+], enables K9 to be calculated at the experimental ionic conditions. Knowledge of K9 permits calculation of cytosolic phosphorylation ratio ([ATP]/[ADP][Pi]), cytosolic free [ADP], free [AMP], standard transformed Gibbs energy of formation (delta fG9 degrees ATP) and the transformed Gibbs energy of the system (delta fG9 ATP) for the biological system. Such information is vital for the quantification of organ and tissue bioenergetics under physiological and pathophysiological conditions.

Direct estimate of bioerosion by two parrotfish species, Chlorurus gibbus and C. sordidus , on the Great Barrier Reef, Australia

Abstract: A description of the daily feeding patterns is provided for the two most abundant bioeroding parrotfish species on the Great Barrier Reef: Chlorurus gibbus and C sordidus This study was based at Lizard Island in the northern section of the GBR Dawn to dusk observations were used to estimate feeding rates and the length of the feeding day The effects of location and season on these values were also examined These data are used to estimate erosion rates by the two species A direct estimate of erosion rates by the two species is provided based on estimated feeding rates and bite sizes In both species, feeding was characterized by an abrupt initiation and termination with relatively consistent feeding rates throughout the day Both species spend 836 to 910% of daylight hours feeding The proportion of daylight hours spent feeding increases in winter, although the actual length of time spent feeding decreases Overall, the two species are similar in their general feeding patterns but differ in their seasonal response to time of day effects C gibbus is conservative with limited site, time of day or seasonal changes in feeding rates In contrast, C sordidus displayed marked seasonal changes in daily feeding rates and diel feeding patterns, with higher feeding rates in the afternoon and in the summer Seasonally adjusted estimates of annual erosion rates per individual of the two species were 10177±1863 kg yr-1 (041±007 m3 yr-1) for C gibbus and 236±34 kg yr-1 (97 10-3±13 10-3 m2yr-1) for C sordidus The likely impact of location and season effects on erosion rates appear to be limited

Consequences of biotransformation of plant secondary metabolites on acid-base metabolism in mammals—A final common pathway?

Abstract: Regulation of acid-base homeostasis is essential for mammals and birds. Biotransformation and metabolism of absorbed plant secondary metabolites (PSMs) results in the production of organic acids that threaten acid-base homeostasis. Consequently these acids must be buffered and excreted from the body. The production of an acid load from detoxified PSMs should occur in herbivorous mammals and birds and with most PSMs and so may provide a unifying theme to explain many effects of PSMs on animal metabolism. Since the organic acids will be largely ionized at physiological pH, disposal of the hydrogen ion and the organic anion may proceed independently. Most hydrogen ions (H+) from organic acids are eliminated by one or more of three ways: (1) when they react with bicarbonate in the extracellular fluid to form carbon dioxide and the carbon dioxide is exhaled, (2) when they bind to dibasic phosphate and are excreted by the kidney as monobasic phosphate, and (3) when they are buffered and retained in the skeletal system. The secretion of phosphate ions and ammonium excretion are two ways in which the kidney replaces bicarbonate ions that have been eliminated as carbon dioxide. Secretion in the kidney tubule is an important means of excreting excessive organic anions rapidly. This process is saturable and may be subject to competition from a variety of different metabolites. Lagomorphs have limited capacity to form new bicarbonate from ammonium excretion and may therefore be obliged to excrete other cations such as sodium to balance the excretion of organic anions from PSMs. Acidemia has wide-ranging impacts on animals but browsing mammals and birds may have to break down muscle tissues to provide for urinary ammonium in order to generate bicarbonate for buffering. Acidemia also can affect the extent of urea recycling. Animals consuming browse diets may have to regulate feeding so that the rate of formation of hydrogen ions does not exceed the rate of disposal. The mechanisms by which this could occur are unknown.

Sequential changes in ovarian follicular dynamics in Bos indicus heifers before and after nutritional anoestrus.

Abstract: This study examined the effects of live mass on ovarian follicular dynamics in heifers before and after the onset of nutritional anoestrus. The effects of decreased live mass on secretion of progesterone, LH and FSH were also investigated. Ovarian characteristics were monitored in 16 postpubertal Brahman heifers using daily transrectal ultrasonography. After two normal oestrous cycles, 11 heifers (treatment group) were allocated to a restricted diet, until the cessation of their oestrous cycles, that resulted in a decrease in live mass of 0.8 kg day-1. Heifers were then fed an ad libitum diet, resulting in increasing live mass until resumption of oestrous cycles. Five heifers (control group) were fed an unrestricted diet throughout the experimental period. The concentrations of progesterone in plasma were monitored twice a week and the concentrations of LH and FSH were determined on day 6 after ovulation, before initiation of dietary restriction, after a 17% decrease in live mass and after the onset of anoestrus in the treatment group. Onset of anoestrus was preceded by linear decreases in the size of ovarian follicles and corpora lutea, and in the persistence of the first dominant follicles of oestrous cycles. These changes were proportional to the decrease in live mass (P < 0.001). The frequency of pulses of LH or mean concentration of FSH on day 6 of the oestrous cycle were not changed after a 17% decrease in live mass, and did not increase following the onset of anoestrus, although concentrations of progesterone were < 0.2 ng ml-1, suggesting that release of LH was suppressed at this time.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of road layout and road environment on driving performance, drivers' physiology and road appreciation

Abstract: Infrastructural changes were implemented on rural 80 km/h roads in The Netherlands in an effort to reduce speeding. The road infrastructure changes were designed to produce discomfort for the speeding driver by providing noxious auditory and haptic feedback. On experimental roads, smooth-surface road width was reduced by using blocks of gravel chippings placed along the centre line and at intervals on road edges. It was predicted that these changes would increase mental load while driving, and thereby decrease speeding. In a field experiment 28 subjects drove an instrumented vehicle over experimental and control roads. A decrease in driving speed and swerving behaviour was found on the experimental roads, and this was coupled with a decrease in heart rate variability, consistent with an increase in mental load. Roads in two different road-side environments (woodland vs. moorland) were also tested. There were differences in driver appraisal of the two environments, but no interactions were observed between these appraisals and driving performance on the experimental roads. It is concluded that the infrastructural measures have a useful role to play in road safety through a reduction in driver speeding.

Adularia in epithermal veins, Queensland: morphology, structural state and origin

Abstract: Four types of adularia (i.e. sub-rhombic, rhombic, tabular and pseudo-acicular) are recognised from examination of samples from ten epithermal vein deposits and prospects in Queensland, based on morphology of the individual crystals. Further investigation of the structural state of adularia reveals that each group has some specific features in terms of the degree of Al/Si disordering, which can be related to various crystallisation conditions and the thermal history. Sub-rhombic adularia is commonly 2–4 mm in size and subhedral with more or less rhombic outlines, and has a relatively ordered Al/Si distribution (2t1 > 0.84), reflecting slow crystallisation conditions. Adularia of this type, in association with coarse-grained quartz, is predominant at deep levels of epithermal systems where boiling is initiated in an environment of low permeability and the fluid is slightly supersaturated with respect to adularia and quartz. Tabular adularia, characterised by its lath-shape and disordered structure (2t1 values ranging from 0.64 to 0.74), is likely to have formed when the fluid moves up to a more permeable environment and starts boiling violently. Relatively high temperatures and rapidly changing conditions account for its special morphology and disordered structure. Rhombic adularia, showing very small crystal size (< 0.2 mm) with euhedral rhombic form, has an intermediate degree of Al/Si ordering. Pseudo-acicular adularia is interpreted as pseudomorphs after carbonate, and its high Al/Si ordered structure is attributed to the presence of a carbonate precursor. These two types of adularia commonly occur within crustiform and colloform bands in association with high grade ore, and chalcedony or fine-grained quartz which often displays various recrystallisation textures. It is most likely that adularias of these two types are formed when extensive boiling is protracted. Microprobe analyses indicate the composition of all adularia types close to pure KAlSi3O8. Sericite- and/or carbonate-altered adularias consistently display more ordered structures, suggesting that the post-crystallisation thermal regime affects the structural state of altered adularia, even at temperatures as low as in epithermal environments.

Multi-scale analysis of habitat association in a guild of blennioid fishes

Abstract: The degree to which reef fish are associated with parhcular reef characteristics has been the subject of much debate It is increasingly clear that the strength of the relationship between reef fish and their habitat may be dependent on the scales at which the reef habitat is categorised Consequently, scale must be explicitly incorporated into any investigation of fish and habitat association I addressed the problem of scale by examining changes in the composition of a guild of blennioid fishes (comprising 13 species in the families Tripterygiidae and Blenniidae) relative to the scale at which their habitat was defined Correspondence Analysis was used to display differences in guild structure At large, geographical scales, characteristic blenniold assemblages could be detected Changes in gulld structure were due partly to differences in numerical dominance of a set of generalist species and, to a lesser extent, species composition At broad scales, the blennioid assemblage displayed speciesspecific depth patterns and association with macroalgal cover A core group of species was found at all depths, while others were restricted in depth and biogenic habitat type The degree of shelter provided by topographic features characterised the blennioid assemblage at fine scales, and habitat specialisation became apparent at this scale The patterns detected in this survey indicate scales at which questions about processes generating these patterns may be profitably addressed 1 conclude that the incorporation of more than 1 scale in ecological studies is useful for reducing ambiguity and for generating a future research program of hypotheses

The regulation of endogeneous energy stores during starvation and refeeding in the somatic tissues of the golden perch

Abstract: Adult golden perch Macquaria ambigua were fed to satiety, starved for up to 210 days, or starved for 150 days then fed to satiety for 60 days to investigate the utilization of energy stores in response to food deprivation and re-feeding. Golden perch sequentially mobilize energy from hepatic tissue, extra-hepatic lipid, and finally muscle components in response to food deprivation. The relative size of the liver was significantly reduced by 30 days after the onset of food deprivation due to the simultaneous mobilization of lipid, protein and glycogen reserves. These stores were renewed rapidly within 30 days by satiety feeding. Mobilization of lipid stores in perivisceral fat bodies occurred between 30 and 60 days of food deprivation. These deposits were also renewed upon re-feeding, although not as rapidly as liver reserves. The glycogen content of the epaxial muscle was reduced by the 60th day of food deprivation but subsequently increased indicating the mobilization of other energy reserves. The concentration of muscle lipid decreased after 90 days of food deprivation. The only significant response in body composition observed in the fish fed to satiety throughout the study was an increase in the relative size of the perivisceral fat bodies. The results of this study suggest that golden perch are well adapted to cope with extended periods of food deprivation, storing energy as perivisceral fat when food is readily available and having a clearly sequential process for mobilizing energy when food is scarce which largely protects the integrity of the musculature.

Evidence that some dinoflagellates contain a ribulose-1,5-bisphosphate carboxylase/oxygenase related to that of the alpha-proteobacteria.

Abstract: The ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) large subunit from several dinoflagellates has a structure similar to that of the Form II enzyme from Rhodospirillum and Rhodobacter species rather than the Form I Rubisco of eukaryotic algae and higher plants. The dinoflagellate Rubisco was identified on native polyacrylamide gels by autoradiographic detection of the stable Rubisco-[2$^{\prime}$-$^{14}$C]-2-carboxy-D-arabinitol 1,5-bisphosphate complex. The antibody to the Symbiodinium sp. large subunit cross reacts with both the Rhodospirillum rubrum and Rhodobacter sphaeroides Form II enzyme whereas antibodies to the R. rubrum Rubisco cross react with a range of dinoflagellate Rubisco large subunits. The N-terminal amino acid sequence of the large subunit from both Symbiodinium sp. and Amphidinium carterae confirmed this relation. The lack of inhibition of the dinoflagellate Rubisco by 6-phosphogluconate is consistent with this structure.

The effects of running, environment, and attentional focus on athletes’ catecholamine and cortisol levels and mood

Abstract: This study was designed to examine some of the psychoneuroendocrine effects of exercise-induced emotional experiences and the mediating effects of environmental setting and subjects' attentional focus Trained runners were tested during an outdoor run and two indoor treadmill running conditions Excretions of catecholamines and cortisol significantly increased after all running conditions but not after a control condition Results indicate that patterns of endocrine and concomitant emotional change through exercise differ when environmental setting and attentional focus are altered in such a way that a normally pleasant task such as running becomes tedious and negatively evaluated These findings support the notion that setting, attention, and cognitive appraisal may alter the emotional experience associated with physical exercise

A new indicator of movement direction during orogenesis: measurement technique and application to the Alps

Abstract: The orientation of axes of sigmoidal, staircase or spiral inclusion trails within porphyroblasts provides an indicator of the direction of movement during deformation that is synchronous with metamorphism. A simple technique is presented in detail to find this axis in 3D by radially sectioning a horizontal slab cut from an oriented sample. When viewed from one direction, the switch in asymmetry of the porphyroblast inclusion trails in these sections defines the trend of the axis. Further radial sectioning of a vertical slab cut parallel to this trend determines the plunge of this axis. This technique is independent of the model adopted for the formation of sigmoidal or spiral-shaped inclusion trails and can be used to evaluate the mechanism by which they form. It can also be used to evaluate theories of folding and orogenesis. Measurements of spiral and sigmoid axes in garnet porphyroblasts from the European Alps show that they reflect the movement of the African Plate relative to Europe better than linear indicators preserved within the same rocks.