bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vegetation of an alkaline pan — acidic peat mosaic in the Hardwood River Valley, Tasmania
Authors: BROWN M. J. , CROWDEN R. K. , JARMAN S. J. 
Published: July 2006

AbstractThe vegetation associated with sandy alkaline pans and surrounding acidic peats in south‐west Tasmania is described. The upper margins of the pans are characterized by sharp environmental discontinuities, with pH changes of more than 3 units in only 20 cm being recorded. Classification and ordination of quadrats by plant species associated with a typical pan showed that five distinct communities are evident, but that these form a gradational series which reflects the altering edaphic status of the sites during infilling of the pans. The pH, drainage and redox characteristics of the substrates are among the factors determining the frequency of particular species at any stage of the progression. Frequency histograms for plant species in and around the pans indicate that many of the species respond individually to changing pH.
Arthropod associates and macronutrient status of the red‐ink sundew (Drosera erythrorhiza Lindl.)
Authors: WATSON A. P. , MATTHIESSEN J. N. , SPRINGETT B. P. 
Published: July 2006

Abstract Arthropods found associated with field populations of the Western Australian red‐ink sundew, Drosera erythrorhiza, were evaluated for their trophic relationship to the plant in a bushland site of the Spearwood Dunes System near Perth. The major prey of Drosera leaves was the collembolan, Hypogastrura vernalis, whose presence in the Perth metropolitan area is a new record for Australia. Additional arthropods found associated with Drosera included primary consumers and opportunistic predators that scavenge captured prey items. Physical models of Drosera leaves were placed in the field and used to estimate potential leaf capture rate immediately prior to Drosera senescence. These data were coupled with nitrogen (N), phosphorus (P), and potassium (K) analysis of soil, Drosera components and insect prey to determine that H. vernalis populations in the study area were sufficient to supply 100% of the observed sundew N and P pool, but a negligible proportion of the K pool. Soil sources of K exceeded any potential contribution of insect K.
Joint use of habitat by red kangaroos and shorthorn cattle in arid central Australia
Authors: DUDZINSKI M. L. , LOWE W. A. , MÜLLER W. J. , LOW BOBBI S. 
Published: July 2006

Abstract The distribution of cattle and red kangaroos among the major communities of a 170 km2 paddock in central Australia was determined from 108 and 82 air surveys respectively over a four and a half year period. Fifty‐nine surveys of each species were used in this report. Changes in use of the communities by the two species were analysed in relation to forage conditions using linear regression techniques. The two species showed trends in time of use of the open and wooded communities. Kangaroos used the mulga‐perennial community (groved Acacia woodland with a shrub and perennial grass understorey) during good forage conditions and moved to the drought refuge open communities when forage conditions deteriorated. Cattle, on the other hand, used the open communities during good forage conditions and tended to move to the mulga communities and the hills when drought began. Mulga‐annual (ungroved Acacia woodland with short grass and forb understorey) was the only major community which showed no clear linear relationship between kangaroo use and forage conditions. This might be a buffer area from which kangaroos come and go as other areas become more attractive as feeding areas. Cattle, however, show some preference for mulga annual during medium forage conditions. There appears to be little spatial interaction by the two species except during drought when kangaroos concentrate on the open communities and some cattle continue to feed in these communities. Community selection seems to be determined mainly by forage conditions, as there is no evidence that one species attracts or repels the other in spatial terms. In the conditions observed, the two species successfully coexisted with some control of numbers of cattle by man.
The life stages and population dynamics of an arid zone scorpion Urodacus yaschenkoi (Birula 1903)
Authors: SHORTHOUSE D. J. , MARPLES T. G. 
Published: July 2006

AbstractThe arid zone scorpion Urodacus yaschenkoi (Birula 1903) is shown to have six instars. Instars can be recognized by measuring the claws and the carapace plus first five tail segments. A population study, carried out at Coombah, NSW, showed that the life history consisted of mating in September–October, 18 month gestation, birth in February‐March, moult to second instar March‐April and annual moults to sixth instar in December–February. The minimum generation time was 6 y, and the population appeared to be stable. The calendar of catches method was used to determine the population size (about 400 animals in 2240 m2) but required some extra assumptions to cope with loss of marks from individuals when they moulted.
Partitioning of nectar sources in an Australian honeyeater community
Authors: FORD HUGH A. , PATON DAVID C. 
Published: July 2006

AbstractFeeding by honeyeaters was found to maintain nectar at low levels at three sites studied on Kangaroo Island in May‐June 1978. The productivity of nectar at a site and position in a dominance hierarchy appeared to determine which bird species used each site. Correa was the main nectar source in the poorest area and produced 0.05 kJ m−2 per day. The small eastern spinebill was the most abundant honeyeater. The purple‐gaped honeyeater also occurred but fed mostly on honeydew. The medium sized New Holland honeyeater was common and territorial in the second area, where Banksia marginata and B. ornata inflorescences and Adenanthos flowers produced 0.7 kJ m−2 of nectar per day. Spinebills and crescent honeyeaters also visited flowers and were sometimes chased by New Holland honeyeaters. The richest site was a flowering Eucalyptus cosmophylla tree (5.1 kJ m−2 of nectar per day). A red wattlebird, the largest honeyeater, held a territory in part of this tree and chased other honeyeaters from the territory. New Holland, crescent and purple‐gaped honeyeaters fed on flowers in other parts of the tree. The spinebill was absent. We conclude that nectar was partitioned along a spectrum of rich to poor sources. Larger more aggressive species used and sometimes defended the richest sources while the smaller birds used the poorer sources.
Biology of Australian and United States strains of Trissolcus basalis, a parasitoid of the green vegetable bug, Nezara viridula
Authors: POWELL JANINE E. , SHEPARD MERLE 
Published: July 2006

AbstractStrains of Trissolcus basalis (Wollaston) Hymenoptera: Scelionidae, an egg parasitoid of the green vegetable bug, Nezara viridula (L.), were obtained from three regions of Australia and from Homestead, Florida (USA). Percent parasitoid emergence was approximately the same for freezer‐stored (‐75°C) and fresh eggs, and freezer‐stored eggs were suitable hosts for a longer time.Optimum host age, oviposition and emergence patterns, mean number of progeny per female, sex ratio and longevity were examined and certain comparisons were made between the Australian and USA parasitoids. Genetic crosses made between males and females of each strain revealed that reproductive isolation did not occur.Higher fecundity of the Australian strains may make them more successful than indigenous (USA) strains for controlling pest populations of N. viridula in the southern USA.
Status of coastal dune communities invaded by Chrysanthemoides monilifera
Authors: WEISS P. W. , NOBLE I. R. 
Published: July 2006

Abstract It has often been assumed that the introduced species Chrysanthemoides monilifera is displacing native species in invaded coastal communities in Australia but no direct evidence has been presented that this displacement is occurring and, if so, to what extent. At an invaded site near Moruya, New South Wales, we found strong negative correlations between the presence (measured as cover, frequency or volume of shrub) of C. monilifera and Acacia longifolia, the hitherto dominant native species, and of C. monilifera and Lomandra longifolia. The negative correlations are partly accounted for by differences in the amounts of each species on different zones on the dune, but the negative correlations remain even within these zones. Also a comparison with uninvaded sites indicates that C. monilifera is displacing A. longifolia from the fore‐dune and mid‐dune but is having less effect in the swale. In addition, there is a trend towards reduced seed production of A. longifolia when growing in proximity to C. monilifera. There is no significant difference in the presence of L. longifolia in the uninvaded and invaded sites. In invaded sites, significantly fewer C. monilifera seedlings occur in the presence of L. longifolia. Thus it appears that the observed negative associations arise from different causes. Chrysanthemoides monilifera is displacing the structurally similar, and previously dominant A. longifolia, while the tussock‐forming L. longifolia is locally hindering the invasion.
Honeybees and the nectar of Echium plantagineum L. in southeastern Australia
Authors: CORBET SARAH A. , DELFOSSE ERNEST S. 
Published: July 2006

Abstract An account is given of the flower of Echium plantagineum in south‐eastern Australia, including stages and timing of flowering, behaviour of raindrops in the flower and aspects of floral microclimate.The concentration of nectar solutes varied with time and site, with means varying from 2 to 62% (as g sucrose/100 g solution). There was a significant negative correlation between nectar solute concentration and ambient relative humidity: the drier the air, the more concentrated the nectar.Rates of nectar secretion per flower varied with the bagging method, with long‐term bagging reducing net secretion rates, possibly because of re‐absorption. Rates varied with time, day and site, with a temporal pattern of change suggesting a link between rates of photosynthesis and secretion. Maximum nectar secretion rates in short‐term bagging experiments were ca. 300 μg sugar/flower/hr (equivalent to > 2 mglflower/24 hr). Secretion rate was correlated with flower density. As flower density increased, secretion rate per flower decreased; rate of sugar production per unit area increased relatively more slowly than flower density. E. plantagineum could produce > 500 mg sugar/m2/day. Honeybees foraged on E. plantagineum only at ambient air temperatures above ca. 17°C unless irradiance exceeded ca. 750 W m‐2. Foragers collected nectar or pollen alone, or both, with the type of visit significantly correlated with nectar solute concentration. Below 35% (as g sucrose/100 g solution) most bees took pollen only; above 40%, most took nectar.Mean standing crop of nectar was generally < 100 μg/flower when most bees were taking nectar, but could exceed 1000 μg/flower when bees were absent or foraging mainly for pollen. Honeybees did not always remove all nectar from flowers they probed. Reabsorption of residual nectar may augment the following day's secretion.
An assessment of a natural wetland receiving sewage effluent
Authors: FINLAYSON MAX , CULLEN PETER , MITCHELL DAVID , CHICK ALAN 
Published: July 2006

AbstractAn assessment of the performance of a wetland dominated by opportunistic weeds in removing nutrients from a secondary sewage effluent was carried out at Thredbo in Kosciusko National Park. Water quality sampling of the inflow and outflow showed a reduction in turbidity, pH and conductivity with passage through the wetland. Dissolved oxygen levels also decreased. In summer 1982, the phosphorus toad of 1.8 kg P day‐1 was reduced by 44% as wastewater moved through the wetland, and the nitrogen load of 6.4 kg N day‐1 by 65%. Winter retentions were 10% and 14% of inflowing loads, respectively. In 1983 there was a net release of phosphorus and reduced retention of nitrogen. This was regarded as being a result of physical disturbance of the wetland. Vegetation downstream of the effluent inflow was dominated by the opportunistic weeds Epilobium sarmantaceum and Rumex crispus. Upstream, Carex gaudichaudiana and Baeckea gunniana dominated. Marked seasonal changes in vigour and biomass were recorded. Plants, but not sediments, downstream of the inflow contained more nutrients than those upstream. Seed bank analysis showed more seeds downstream than upstream. A moist treatment promoted more seed germination than a flooded treatment. E. sarmantaceum and to a lesser extent R. crispus dominated in each treatment. In an effort to promote greater water retention and replacement of the weed species, channels in the wetland have been blocked with gravel and planted with Phragmites australis and Schoenoplectus validus.
Immediate and longer‐term effects of fire on seed predation by ants in sclerophyllous vegetation in south‐eastern Australia
Authors: ANDERSEN ALAN N. 
Published: July 2006

AbstractFollowing a prescribed spring fire at a woodland site with heathy understorey in south‐eastern Australia, the following features changed markedly: the composition of the ant fauna taken in pitfall traps; the abundance of seed‐eating species; seedfall from woody‐fruitedEucalyptus obliquaandCasuarina pusilla; and rates of seed predation by ants. Broadly adapted species ofMonomoriumandRhytidoponera, uncommonly recorded before the fire, became the most abundant ants caught. Seed removal from baits dropped by almost half during the week after fire, despite an increased catch of seed‐eatingRhytidoponera tasmaniensis. This coincided with a massive fire‐induced release of seeds stored inside woody fruits, suggesting that predator satiation occurred.The fall ofCasuarinaseeds andEucalyptuschaff returned to pre‐fire (low) levels 1 week after the fire, but a substantial proportion ofEucalyptusseeds fell after several weeks. By this time rates of seed removal were increasing rapidly as the abundance of seed‐eatingR. tasmaniensiscontinued to increase. Weekly removal from baits reached 100% 7 weeks after the fire, which was much higher than any level recorded before it. Results from a nearby heathland site, burned by an earlier fire, indicated that unusually high rates of seed removal, paralleling increases in abundance ofR. tasmaniensis, can persist for at least 2 years following fire. These results have potentially important implications for post‐fire recruitment.
Spatial variability of experimental fires in south‐west Western Australia
Authors: HOBBS RICHARD J. , ATKINS LYN 
Published: July 2006

AbstractDescriptions of fire behaviour and severity are often limited to single measures of intensiv and some assessment of spread rates. This study examined the small‐scale variability in fire severity during three prescribed fires in shrub and woodland communities in south‐west Western Australia. Using Thermocolor pyrometers, the temperatures reached during the fires were found to vary spatially, because of variation in fuel distribution and type. Different shrub species also reached different temperatures during ignition. Temperatures at and just below the soil surface also varied greatly. Only in a very intense fire caused by heavy fuel loads was a uniform fire treatment experienced. Such fire variability may be important in determining post‐fire vegetation response, especially where temperature‐dependent germination or coneopening occurs. In fire studies some estimate of fire variability should be obtained to allow adequate explanation of subsequent regeneration patterns.
Dynamics of root growth and decay in two grasses native to semi‐arid Argentina
Authors: DISTEL ROBERTO A. , FERNÁNDEZ OSVALDO A. 
Published: July 2006

AbstractThe pattern of root growth and decay in Stipa tenuis Phil, and Piptochaetium napostaense (Speg.) Hack, was examined under field conditions in root observation chambers. The roots of both species grew uninterruptedly throughout the whole year. Root elongation during spring, summer, and early autumn can be six and five times as high as that in the late autumn to winter period for S. tenuis and P. napostaense, respectively. Root decay was a continuous process in both species throughout the year, with maximum decay rates occurring from late spring through to the middle of autumn. Comparison of minimum and maximum values registered during the year showed a root decay ratio of about 4:1 for S. tenuis and one of 5:1 for P. napostaense. During the period of maximum root growth, both species showed a pulse‐like pattern of root elongation in response to rapid changes in water availability. In a semi‐arid region in which the soil is notably shallow, root growth behaviour of this kind should allow these species to respond opportunistically to water.
Effects of the cholesterol‐lowering compound methyl‐β‐cyclodextrin in models of α‐synucleinopathy
Authors: Bar‐On Pazit , Rockenstein Edward , Adame Anthony , Ho Gilbert , Hashimoto Makoto , Masliah Eliezer 
Published: July 2006

AbstractThe aggregation of α‐synuclein (α‐syn) is believed to play a critical role in the pathogenesis of disorders such as dementia with Lewy bodies and Parkinson's disease. The function of α‐syn remains unclear, although several lines of evidence suggest that α‐syn is involved in synaptic vesicle trafficking, probably via lipid binding, and interactions with lipids have been shown to regulate α‐syn aggregation. In this context, the main objective of this study was to determine whether methyl‐β‐cyclodextrin (MβCD), a cholesterol‐extracting agent, interfered with α‐syn accumulation in models of synucleinopathy. For this purpose, we studied the effects of MβCD on the accumulation of α‐syn in a transfected neuronal cell line and in transgenic mice. Immunoblot analysis showed that MβCD reduced the level of α‐syn in the membrane fraction and detergent‐insoluble fraction of transfected cells. In agreement with the in vitro studies, treatment of mice with MβCD resulted in decreased levels of α‐syn in membrane fractions and reduced accumulation of α‐syn in the neuronal cell body and synapses. Taken together, these results suggest that changes in cholesterol and lipid composition using cholesterol‐lowering agents may be used as a tool for the treatment of synucleinopathies.
Regulation of N‐acetylaspartate and N‐acetylaspartylglutamate biosynthesis by protein kinase activators
Authors: Arun Peethambaran , Madhavarao Chikkathur N. , Moffett John R. , Namboodiri M. A. Aryan 
Published: July 2006

AbstractThe neuronal dipeptide N‐acetylaspartylglutamate (NAAG) is thought to be synthesized enzymatically from N‐acetylaspartate (NAA) and glutamate. We used radiolabeled precursors to examine NAA and NAAG biosynthesis in SH‐SY5Y human neuroblastoma cells stimulated with activators of protein kinase A (dbcAMP; N6,2′‐O‐dibutyryl cAMP) and protein kinase C (PMA; phorbol‐12‐myristate‐13‐acetate). Differentiation over the course of several days with dbcAMP resulted in increased endogenous NAA levels and NAAG synthesis from l‐[3H]glutamine, whereas PMA‐induced differentiation reduced both. Exogenously applied NAA caused dose dependent increases in intracellular NAA levels, and NAAG biosynthesis from l‐[3H]glutamine, suggesting precursor–product and mass–action relationships between NAA and NAAG. Incorporation of l‐[3H]aspartate into NAA and NAAG occurred sequentially, appearing in NAA by 1 h, but not in NAAG until between 6 and 24 h. Synthesis of NAAG from l‐[3H]aspartate was increased by dbcAMP and decreased by PMA at 24 h. The effects of PMA on l‐[3H]aspartate incorporation into NAA were temporally biphasic. Using short incubation times (1 and 6 h), PMA increased l‐[3H]aspartate incorporation into NAA, but with longer incubation (24 h), incorporation was significantly reduced. These results suggest that, while the neuronal production of NAA and NAAG are biochemically related, significant differences exist in the regulatory mechanisms controlling their biosynthesis.
Retracted: Deposition of iron and β‐amyloid plaques is associated with cortical cellular damage in rabbits fed with long‐term cholesterol‐enriched diets
Authors: Ghribi Othman , Golovko Mikhail Y. , Larsen Brian , Schrag Matthew , Murphy Eric J. 
Published: July 2006

AbstractHypercholesterolemia is a potential trigger of Alzheimer's disease, and is thought to increase brain levels of β‐amyloid (Aβ) and iron. However, animal models to address the mechanisms by which Aβ and iron accumulation may cause neuronal damage are poorly defined. To address this question, we fed adult rabbits a 1% cholesterol‐enriched diet for 7 months. This diet was associated with increased regional deposition of both iron and Aβ peptide in the brain. Iron preferentially accumulated around Aβ plaques in the adjacent cortex, but was not found in the hippocampus. Co‐localization of iron and Aβ was accompanied by apoptosis, DNA damage, blood–brain barrier (BBB) disruption, as well as dysregulation in the level of the iron‐regulatory proteins, ferritin and heme‐oxygenase‐1. We further demonstrate that the cholesterol diet‐induced apoptosis is mediated by the activation of the endoplasmic reticulum stress pathway, involving the down‐regulation of the endoplasmic reticulum chaperones, calreticulin, grp78 and grp94, and the activation of the growth and arrest DNA damage protein, gadd153. Our results suggest that BBB damage and disturbances in iron metabolism may render the cortex more vulnerable than the hippocampus to the cholesterol‐induced cellular stress.
Neuron–astrocyte interactions in the regulation of brain energy metabolism: a focus on NMR spectroscopy
Authors: Escartin Carole , Valette Julien , Lebon Vincent , Bonvento Gilles 
Published: July 2006

AbstractAn adequate and timely production of ATP by brain cells is of cardinal importance to support the major energetic cost of the rapid processing of information via synaptic and action potentials. Recently, evidence has been accumulated to support the view that the regulation of brain energy metabolism is under the control of an intimate dialogue between astrocytes and neurons. In vitro studies on cultured astrocytes and in vivo studies on rodents have provided evidence that glutamate and Na+ uptake in astrocytes is a key triggering signal regulating glucose use in the brain. With the advent of NMR spectroscopy, it has been possible to provide experimental evidence to show that energy consumption is mainly devoted to glutamatergic neurotransmission and that glutamate‐glutamine cycling is coupled in a ∼ 1 : 1 molar stoichiometry to glucose oxidation, at least in the cerebral cortex. This improved understanding of neuron–astrocyte metabolic interactions offers the potential for developing novel therapeutic strategies for many neurological disorders that include a metabolic deficit.