bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of the FGF and MEK signaling pathway in the ascidian embryo
Authors: Kim Gil Jung , Nishida Hiroki
Published: March 2003

In the ascidian embryo, a fibroblast growth factor (FGF)‐like signal from presumptive endoderm blastomeres between the 32‐cell and early 64‐cell stages induces the formation of notochord and mesenchyme cells. However, it has not been known whether endogenous FGF signaling is involved in the process. Here it is shown that 64‐cell embryos exhibit a marked increase in endogenous extracellular signal‐regulated kinase (ERK/MAPK) activity. The increase in ERK activity was reduced by treatment with an FGF receptor 1 inhibitor, SU5402, and a MEK (ERK kinase/MAPKK) inhibitor, U0126. Both drugs blocked the formation of notochord and mesenchyme when embryos were treated at the 32‐cell stage, but not at the 2‐ or 110‐cell stages. The dominant‐negative form of Ras also suppressed notochord and mesenchyme formation. Both inhibitors suppressed induction by exogenous basic FGF. These results suggest that the FGF signaling cascade is indeed necessary for the formation of notochord and mesenchyme cells during ascidian embryogenesis. It is also shown that FGF signaling is required for formation of the secondary notochord, secondary muscle and neural tissues, and at least ERK activity is necessary for the formation of trunk lateral cells and posterior endoderm. Therefore, FGF and MEK signaling are required for the formation of various tissues in the ascidian embryo.
β‐Catenin‐dependent Wnt signaling in apical ectodermal ridge induction and FGF8 expression in normal and limbless mutant chick limbs
Authors: McQueeney Kelly , Soufer Renee , Dealy Caroline N.
Published: March 2003

The fibroblast growth factor (FGF) and β‐catenin‐dependent Wnt signaling pathways are key regulators of vertebrate limb development. FGF10 induces expression of Wnt3a, which regulates the formation and FGF8 expression of the apical ectodermal ridge (AER). In amelic limbless limbs, an AER fails to form and FGF8 is not expressed, despite expression of FGF10. It has been found that Wnt3a is initially expressed in limbless ectoderm, although subsequently is drastically reduced. In addition, changes in the expression pattern or level of several Frizzled receptors, Axin, Lef1/Tcf1 and β‐catenin have been found in limbless limbs. Notably, while normal wing buds respond to LiCl‐stimulated activation of β‐catenin‐dependent signaling by forming ectopic, FGF8‐expressing AER, LiCl was unable to induce an AER in limbless wing buds. The results of this study suggest that the limbless gene is required for β‐catenin‐dependent Wnt signaling in limb ectoderm leading to FGF8 expression and AER formation.
Gα3 and protein kinase A represent cross‐talking pathways for gene expression in Dictyostelium discoideum
Authors: Brandon Maureen A. , Mahadeo Dana C. , Podgorski Gregory J.
Published: March 2003

Heterotrimeric G proteins and protein kinase A (PKA) are regulators of development in Dictyostelium discoideum. It has been reported that disruption of the Dictyostelium Gα3 gene (gα3–) blocks development and expression of several early development genes, characteristics that are reminiscent of mutants lacking the catalytic subunit of PKA (pkac–). The hypothesis that Gα3 and PKA signaling pathways may interact to control developmental gene expression was tested by comparing the regulation of seven genes expressed early in development in the wild‐type and in gα3– and pkac– mutants, and comparing PKA activity in the wild‐type and in a gα3– mutant. The expression patterns of six genes were affected similarly by the Gα3 and PKA mutations, while the expression of only one gene, the cAMP receptor 1 (cAR1), differed between the mutants. PKA activity, measured by phosphorylation of the PKA‐specific substrate Kemptide, was higher in gα3– cells than in wild‐type cells, suggesting that Gα3 normally exerts an inhibitory effect on PKA activity. Although some early development genes appear to require both Gα3 and PKA for expression, the differing response of cAR1 expression and the inhibitory effect of Gα3 on PKA activity suggest that Gα3 and PKA are members of interacting pathways controlling gene expression early in development.
Methane and hydrogen production in a termite‐symbiont system
Authors: SUGIMOTO ATSUKO , INOUE TETSUSHI , TAYASU ICHIRO , MILLER LEIGH , TAKEICHI SATOKI , ABE TAKUYA
Published: March 2003

Methane and hydrogen emission rates and the δ13C of CH4 were observed for various termites in Australia, Thailand and Japan. Combined with the already reported emission rates of CH4 in the literature, the phylogenetic trend was examined. Emission rates of the observed termites were categorized into five groups: group I with high CH4 and low H2 emission rates with a CH4/H2 ratio of typically 10/1; group II with high CH4 and high H2 emissions with a CH4/H2 ratio of 4/1–1/2; group III with low emission rates of CH4 and H2; group IV with high H2 and insignificant CH4 emissions; and group V with insignificant emissions for both CH4 and H2. In lower termites, there are both colonies infected and uninfected with methanogens even in the same species, and no specific trend in CH4 and H2 emissions was observed within a genus. Whether protozoa in the hindgut of termites are infected with methanogens or not and the differences in species compositions of protozoa are possibly responsible for the inter‐colonial variations. The proportions of infected colonies were possibly small for the family Kalotermitidae (dry wood feeders), and relatively large for families of wet or damp wood feeders. The hydrogen emission rate possibly depends on the locality of methanogens: namely, whether they are intracellular symbionts of protozoa or whether they are attached to the hindgut wall. Emission rates of higher termites were classified into groups according to genera and the diet. Most species of soil or wood/soil interface feeders classified into group I, while the soil feeders Dicuspiditermes in Thailand and Amitermes in Australia were classified into groups with high H2 emission rates. Typical wood‐feeding termites and fungus‐growing termites were classified into group III. The results indicate that higher termites tend to increase the CH4 emission rate during dietary evolution from wood‐ to soil‐feeding, and two types of the system with different efficiencies of interspecies transfer of H2 have been formed. The δ13C of CH4 was discernible with a difference in the decomposition process in the termite–symbiont system among lower termites, fungus‐growing termites and other higher termites.
Spatial pattern changes in aboveground plant biomass in a grazing pasture
Authors: Shiyomi Masae , Okada Mari , Takahashi Shigeo , Tang Yanhong
Published: March 2003

Using gamma distribution and spatial autocorrelation, it was demonstrated that plant biomass per unit area of a pasture grazed by cattle exhibited two kinds of spatial heterogeneity: small‐scale heterogeneity caused by grazing and large‐scale heterogeneity caused by topography, land aspect, etc. For each of the 10 measurement times from May to August, 100 quadrats 50 cm × 50 cm were arranged along a straight line 50 m long in a pasture, and the plants within the quadrats were harvested at the height of 3 cm above the ground surface to measure the dry weight. The data were aggregated into frequency distributions, and gamma distribution and the parameter values were estimated. This analysis showed that with the progression of grazing the amount of biomass decreased and the degree of spatial heterogeneity in biomass, measured per 0.25 m2, increased, and due to plant regrowth the trends were reversed. By rearranging the 100 biomass data in order of weight, it was suggested that plots with an extremely large biomass were not grazed by cattle and remained in the pasture. For the same data, variations of biomass along the straight line were divided into two parts based on the moving average: the spatial trend and the residuals which cannot be explained by the trend. In this analysis, 48–75% of the total spatial variation was explained by the trend along the straight line. Analysis using spatial autocorrelation for the actual biomass changes showed that the biomass changes within a range of about 10 m on the straight line gave a positive correlation, which indicates a topographical trend in biomass. Spatial autocorrelation for residuals suggested that the spatial changes in biomass along the straight line followed a wave‐like or checker‐board pattern. Small‐scale spatial heterogeneity in plant biomass may be caused by the uneven deposition of excreta by grazing animals, uneven use of the grassland by grazing animals, and uneven dispersal of plant seeds through faeces over the grassland. The possibility that such unevenness might accelerate energy flow in the grassland ecosystem and contribute to grassland sustainability is discussed.
Competitive ability of two Brassica varieties in relation to biomass allocation and morphological plasticity under varying nutrient availability
Authors: Li Bo , Suzuki Jun‐Ichirou , Hara Toshihiko
Published: March 2003

Green cabbage (Brassica campestris, leafy variety) and turnip (Brassica campestris var. rapifera, rooty variety) were grown in both monocultures and mixtures at three nutrient levels to investigate their responses to nutrient availability with respect to biomass allocation, morphological plasticity and competitive ability. Their allocation parameters and leaf morphological traits were affected by both nutrient availability and developmental stage. Both of the varieties had a smaller biomass allocation to leaf blades, but a greater allocation to petioles at high nutrient levels. Root:shoot ratio (RSR) of green cabbage decreased with increasing nutrient availability, whereas that of turnip increased. Turnip had a smaller leaf blade weight ratio (LBWR) than cabbage, being compensated for by larger leaf area ratio (LAR) and specific leaf area (SLA). Leaf area ratio and SLA of both the varieties increased with increasing nutrient availability as did their mean dry weights. The mean dry weight of turnip was slightly greater than that of green cabbage in their respective monocultures, while that of green cabbage was greater than that of turnip in their 1:1 mixture. Therefore, green cabbage, having inherently greater biomass allocation to leaves, was generally more competitive than turnip with more biomass allocation to roots, especially at higher nutrient levels. However, within a variety, morphological plasticity (variation in LAR and SLA) was more important than the plasticity in biomass allocation (e.g. variation in RSR and LBWR) in determining competitive ability. The implication of our results is that competition models based on biomass allocation pattern alone may fail to predict competitive outcomes and that such models should also take morphological plasticity into full account.
Estimation of mycelial biomass of arbuscular mycorrhizal fungi associated with the annual legume Kummerowia striata by ergosterol analysis
Authors: Fujiyoshi Masaaki , Nakatsubo Takayuki , Ogura Satoko , Horikoshi Takao
Published: March 2003

The biomass of internal and external mycelia of an arbuscular mycorrhizal (AM) fungus, Gigaspora margarita Becker & Hall, symbiotic with the annual legume, Kummerowia striata (Thunb.) Schindler, was estimated in a sterile culture experiment. When ergosterol, which is a component of fungal cell membranes, was measured in the mycorrhizal roots and soil at 20, 40, 60 and 80 days after inoculation with the AM fungus, the content of ergosterol in the roots increased from 0.036 μg per plant (at 20 days) to 1.85 μg per plant (at 80 days). Ergosterol content in the soil also increased with time, but the ratio of external to internal mycelial biomass decreased from 24.7 at 40 days to 5.6 at 80 days after sowing. The average ergosterol concentration in the external mycelia of G. margarita was 0.63 mg g−1. It was estimated that at 80 days after inoculation, the biomass of internal and external mycelia of the AM fungus accounted for approximately 16 and 92% of root biomass, respectively. For comparison, ergosterol content in the roots of K. striata growing in the field was also measured. The results suggest that AM fungi can be a large sink of the carbon that is assimilated by the host plants.
Community dynamic models of two dioecious tree species
Authors: Nanami Satoshi , Kawaguchi Hideyuki , Kubo Takuya
Published: March 2003

The effects of dioecy on community dynamics were examined by using transition matrix models for two dioecious tree species, one a superior competitor with a narrow dispersal range and the other an inferior competitor with a wide dispersal range. The models are based on tree‐by‐tree replacements in each identical microsite occupied by either male or female canopy trees of the superior competitor and canopy trees of the inferior competitor. Coexistence of the two species is possible not only because of a trade‐off between competitive and dispersal abilities but also because of the existence of a ‘competitor gap’, which the superior competitor cannot occupy. The competitor gap is created under the male trees of the superior competitor. The inferior competitor occupies the competitor gap because of its wide dispersal range. The relative abundance of the two species depends on the dispersal ability and sex ratios of the superior competitor. The decreasing dispersal ability and the female abundance of the superior competitor increase the competitor gap, which allows the regeneration of the inferior competitor.
Parasitism strategy of the grey starling, Sturnus cineraceus: Selection based on host characters and nest location
Authors: Yamaguchi Yasuhiro
Published: March 2003

The strategy used by the intraspecific brood parasite, the grey starling, Sturnus cineraceus (Temminck) and the degree to which this strategy reflected the sources of mortality for parasite eggs were examined. Approximately 74% of all parasite eggs failed to produce young that survived to fledglings. Most of this mortality was due to two factors: (i) laying in a nest that had been deserted by a host during its nesting cycle (19%); and (ii) mismatched timing of laying in the host’s nesting cycle (38%). It is important for parasites to select a suitable host in order to avoid this mortality and increase their reproductive success. However, grey starlings did not select hosts on the basis of nest location, host characteristics, or laying date. Lack of attention to these factors implies a failure on the part of the grey starlings to recognize cues that could direct them to select host nests that would provide the best environment for their eggs. Although some egg loss and egg replacement occurred before clutch initiation by hosts, no evidence was found that parasitic birds removed host eggs after clutch initiation by hosts. These results suggest that parasites did not adopt a successful strategy for enhancing the survival rate of their own eggs.
Effects of herbivore‐bearing adult trees of the oak Quercus crispula on the survival of their seedlings
Authors: Wada Naoya , Murakami Masashi , Yoshida Kunikichi
Published: March 2003

The acorn‐producing oak Quercus crispula Blume is shade‐tolerant and its seedlings were found to be underdispersed on the forest floor, forming seedling aggregations near fertile canopy trees. However, 84.4% of the seedlings were dead within 2 years, with the highest mortality near the adult canopy trees of Q. crispula. This was mostly due to the high levels of herbivory by lepidopteran larvae. The most serious damage was caused by spring consumers, which fed on the leaves of canopy trees in June and, when the food quality of the leaves declined, fell down to the forest floor to consume the juveniles, including the seedlings. Contrary to the expectation of the herbivore–host arms race theory, most of the herbivores were polyphagous. The most dominant spring consumer Telorta edentata (Leech) was also polyphagous, and its distribution on the forest floor showed a high level of association with the distribution of dead oak seedlings.
Improved growth and water use efficiency of cherry saplings under reduced light intensity
Authors: Centritto Mauro , Loreto Francesco , Massacci Angelo , Pietrini Fabrizio , Villani Maria C. , Zacchini Massimo
Published: March 2003

Cherry (Prunus aviumL.) saplings were grown under natural sunlight (controls) or moderate shading (up to 30%, depending on the incident light intensity and the hour of the day). Reduced light intensity increased the dry mass of each of the plant components studied. Consequently, the total dry mass of shaded plants was significantly greater than that of controls at the end of the growing season. However, the diurnal trend in the level of photosynthesis (per unit of leaf area) of shaded plants was similar to the controls in August, but lower in September. As the growing season proceeded, reduced photosynthetic rates, thinner mesophyll and larger specific leaf area in the shaded plants indicated that leaf development had adapted to shaded conditions throughout the growing season. It is suggested that increased growth of shaded plants was caused by a higher initial relative growth rate and a greater whole‐plant photosynthesis. Shading consistently reduced transpiration over the season, therefore improving water use efficiency of shaded leaves. Our results suggest that a moderate reduction in light intensity can be a useful method for improving growth and saving water in hot and dry environments.
Variations in sexual and asexual reproduction of Scirpus mariqueter along an elevational gradient
Authors: Sun Shucun , Gao Xianming , Cai Yongli
Published: March 2003

In order to assess the importance of sexual and asexual reproduction during the life history of Scirpus mariqueter, its reproductive and growth characters were concurrently examined along an elevational gradient (from low elevation to high elevation). The proportions of flowering shoot and inflorescence mass, seed : flower ratio and seed weight were used to quantify the investment in sexual reproduction. The proportions of current‐year shoot and rhizome mass were used to quantify the investment in asexual reproduction, and the proportion of corm mass was used for growth, respectively. It was found that vegetative propagation predominated at low elevation, whereas sexual reproduction predominated at high elevation; and that sexual reproduction increased with declining asexual reproduction along the gradient. The results suggest that asexual reproduction is relatively favored in the early life stage, whereas sexual reproduction is favored when the population becomes mature and aged, probably because of the functional differentiation between the two reproductive types. Sexual productive characters (i.e. the proportions of flowering shoot and inflorescence mass) were negatively correlated to both growth and asexual reproductive characters along the gradient, indicating there might exist some trade‐offs among growth, sexual and asexual reproduction during the life history. However, no obvious pattern was found between asexual reproductive characters and growth characters along the elevational gradient, possibly because of the varied relationships between them at different life stages. The variations in sexual and asexual reproduction in the species and the relationship between them are thought to be of great significance for local population growth, species persistence and evolution.
Variable correspondence of female host preference and larval performance in a phytophagous ladybird beetle Epilachna pustulosa (Coleoptera: Coccinellidae)
Authors: Fujiyama Naoyuki , Katakura Haruo
Published: March 2003

Genetic and environmental factors causing intraspecific variation of the thistle Cirsium kamtschaticum Ledeb. as a host plant of the phytophagous ladybird Epilachna pustulosa Kôno were investigated through simple food‐choice tests and rearing of larvae. Two thistle clones (T1U1 and T4H2) were used, originally growing approximately 12 km apart. A previous study showed that adult female ladybirds preferred T1U1 to T4H2, and that larval performance was better on T1U1, when leaves from the clones in situ were examined. The two clones retained their characteristics with respect to beetle preference after transplantation into a common garden. However, the difference between T1U1 and T4H2 with respect to larval performance was reduced after the transplantation. When leaves from shoots of T1U1 exposed to different sunlight intensities were offered, adult female ladybirds did not show obvious preferences. Larval eclosion rates increased significantly with the increase in leaf sunlight intensity exposure. These results suggest strongly that both genetic and environmental factors are involved in interclonal variation of thistle quality in beetle preference and/or performance. It is suggested that the quality of thistle leaves for larval performance is largely affected by environmental factors, while leaf quality for beetle preference may be determined strictly by genetic factors. Under certain conditions, E. pustulosa females may behave maladaptively, preferring plants not appropriate for larval growth, or not choosing plants appropriate for the larval growth.
Ecological study of pseudoscorpion fauna in the soil organic layer in managed and abandoned secondary forests
Authors: Yamamoto Tetsuya , Nakagoshi Nobukazu , Touyama Yoshifumi
Published: March 2003

We surveyed pseudoscorpion fauna in the soil organic layer in managed and abandoned secondary forests in Hiroshima Prefecture, Japan, and studied the effects of forest management on the pseudoscorpions. The vegetation structure was generally more developed in abandoned stands than in managed stands. The depth of the soil organic layer was not significantly different between the two stand types. We observed a total of seven pseudoscorpion species belonging to five genera. Pseudoscorpion species richness and densities were higher in abandoned stands than in managed stands. We did not find any pseudoscorpions in stands where the summed vegetation cover was less than 150%.
Local neighborhood effects on long‐term survival of individual trees in a neotropical forest
Authors: Hubbell Stephen P. , Ahumada Jorge A. , Condit Richard , Foster Robin B.
Published: March 2003

The survival of approximately 235 000 individual tropical trees and saplings in the 50 ha permanent plot on Barro Colorado Island (BCI), Panama was analyzed over a 13‐year interval (1982–1995) as a function of four biotic neighborhood variables: (i) total stem density; (ii) conspecific density; (iii) relative plant size; and (iv) relative species richness. These neighborhood variables were measured in annular rings of width 2.5 m, extending 30 m from a given focal plant, and in one more distant annulus at 47.5–50 m. Because survival was spatially autocorrelated, a Gibbs sampler and a Monte Carlo Markov chain method were used for fitting an autologistic regression model to obtain unbiased estimates of parameter variances for hypothesis testing. After pooling all species at the community level, results showed that all four variables had significant and often strong effects on focal plant survival. Three of the four variables had negative effects on focal plant survival; relative plant size was the only variable with a positive effect (18% increase in the survival odds ratio). The variables with a negative effect on the survival odds ratio, in order of their effect strength in the nearest annulus, were: stem density (a 70% reduction in the survival odds ratio), conspecific density (50% reduction) and species richness (13% reduction). A guild‐level analysis revealed considerable heterogeneity among guilds in their responses to these variables. For example, survival of gap species showed a much larger positive response to relative plant size than did survival of shade‐tolerant species. Survival of shrub species was positively affected by conspecific density, but canopy tree survival was negatively affected. Conspecific density negatively affected survival of rare species much more strongly than survival of common species. The neighborhood effects of conspecific density disappear within approximately 12–15 m of the focal plant. Although locally strong, the rapid spatial decay of these effects raises unanswered questions about their quantitative contribution to the maintenance of tree diversity on landscape scales in the BCI forest.
Design and analysis of biodiversity field experiments
Authors: Deutschman Douglas H.
Published: March 2003

The design and analysis of field experiments have figured prominently in the current debate about biodiversity and ecosystem function. These debates have identified important issues about species traits, functional groups, and community assembly, but a broader debate needs to include discussions about the scale (grain and extent) of experiments relative to natural spatial and temporal heterogeneity. In addition, alternative statistical analyses need to be explored that focus on comparison among several statistical models rather than simple hypothesis testing. Analyses of the first 2 years of data from a new biodiversity field experiment are used to illustrate these concepts. A traditional one‐way ANOVA demonstrates the expected increase in aboveground biomass with higher levels of vascular plant diversity. Further analysis demonstrates that this relationship is absent when the community contains either Arrhenatherum
elatius or Holcus lanatus, two dominant species of grass. Variance in biomass is also a function of diversity and both spatial and temporal heterogeneity are significant factors in the analysis despite precautions taken to minimize them. These examples illustrate the degree to which the analysis of a field experiment influences the interpretation of the observed results. Ultimately, results from field experiments must be validated through continued comparisons among field experiments, mathematical models, laboratory trials, and mesocosm experiments.
Spatial and seasonal heterogeneity in understory light conditions caused by differential leaf flushing of deciduous overstory trees
Authors: Kato Shogo , Komiyama Akira
Published: March 2003

In a deciduous broad‐leaved forest, we investigated the seasonality and heterogeneity of understory light conditions in relation to the leaf phenology of overstory trees. Fisheye photographs were taken from spring to autumn to estimate direct and indirect light conditions above the understory. Spatial variation in daily direct photosynthetic photon flux density (PPFD) was highest in late May, when the early and the intermediate‐flushing trees had finished flushing and the late‐flushing trees had just started flushing. After whole canopy closure, spatial variation in direct PPFD became low. Thus, asynchronous overstory leaf flushing in spring resulted in spatial heterogeneity in understory light conditions. These results suggest that the leaf phenological patterns of overstory trees are an important factor in the formation of the understory community.
Storage ability of overwintering leaves and rhizomes in a semi‐evergreen fern, Dryopteris crassirhizoma (Dryopteridaceae)
Authors: TANI TOMOKAZU , KUDO GAKU
Published: March 2003

Dryopteris crassirhizoma is a rhizomatous semi‐evergreen fern growing in the understory of deciduous forests. Although the top portion of the overwintering leaves began to wither in early winter, intensive senescence occurred in the spring, concurrently with new leaf development. Dry weight comparisons between organs revealed that the rhizome occupied the largest proportion of the total mass, followed by the pinnae. To assess the storage ability of overwintering leaves and the rhizome, seasonal changes in nitrogen content and the dry mass of pinnae and the rhizome were measured. Nitrogen (36.6%) was resorbed from winter‐withering pinnae, but not from spring‐withering pinnae. In contrast, a similar decrease in dry mass per unit area occurred between winter‐ and spring‐withering pinnae (∼15%). These results indicate that overwintering leaves serve as a carbohydrate storage organ, but do not serve as a nitrogen storage organ. Nitrogen was not translocated from the rhizome during the early growing season, but translocation did occur in late summer and autumn. The dry mass of the rhizome decreased by 18.4% in spring, at the time of new leaf expansion. The amount of exported dry matter from the rhizome was threefold larger than that from senescent pinnae. Therefore, the rhizome is a major carbohydrate storage organ in this species, although overwintering leaves also act as a carbohydrate storage organ.
Habitat differentiation of Lauraceae species in a tropical lower montane forest in northern Thailand
Authors: SRI‐NGERNYUANG KRIANGSAK , KANZAKI MAMORU , MIZUNO TAKASHI , NOGUCHI HIDEYUKI , TEEJUNTUK SAKHAN , SUNGPALEE CHETTHA , HARA MASATOSHI , YAMAKURA TAKUO , SAHUNALU PONGSAK , DHANMANONDA PRICHA , BUNYAVEJCHEWIN SARAYUDH
Published: March 2003

Dependency on topographical habitat was examined for Lauraceae tree species in a lower montane forest using a large‐scale research plot established at Doi Inthanon National Park, northern Thailand. Twenty species of 10 genera of Lauraceae were recorded in a 7.5‐ha part of the plot; Lauraceae accounted for 18% of the total basal area. Lauraceae was the most species‐rich and most abundant family in the plot. In a cluster analysis based on the matrix of spatial associations between species, two clusters were recognized. Members of one cluster seemed to associate with lower‐elevation habitats, and members of the other associated with habitats on ridges. By subdividing the study plot into 20 m × 20 m squares, a discriminant analysis could be applied to the presence–absence data for the 17 species that had sufficient population density. The predictor variables used were the relative elevation, slope inclination, slope direction (transformed to deviation from SSW) and slope convexity for each of the squares. The discriminant models were tested statistically by applying the random shift technique. The models were significant for 11 of the species (65% of the species examined) and were associated with the topographical condition of the habitat. Stepwise selection of the predictor variables for these 11 species revealed that relative elevation and slope convexity were the most important factors for predicting the presence or absence of the Lauraceae species. Both these variables were considered to indicate the hydrological condition of the habitat.
Spatial and temporal variations in insect‐infested acorn fall in a Quercus liaotungensis forest in North China
Authors: YU XIAODONG , ZHOU HONGZHANG , LUO TIANHONG
Published: March 2003

Three plots with different aspects and slope characteristics were surveyed in 1999 and 2000 to clarify the spatial and temporal variations in insect‐infested acorn fall patterns in a Quercus liaotungensis Koidz. forest in the Dongling Mountain region, North China. There was a significant difference in the proportion of infested acorns in the three plots in a low crop year, but not in a mast year. Within oakwoods on the southeast‐facing slope, the insect infestation rate on the upper slope was significantly higher than on the lower slope, but not in the northwest‐facing plot. Infestation rate in the low crop year in all three plots was significantly higher than infestation in the mast year. Most of the early fallen acorns had a higher proportion of insect infestation, and in the mast year it was much more obvious than in the low crop year. The proportion of infested acorns in seed bank along the topographic gradient showed a similar decreasing trend with acorn fall time, but the proportion on the upper slope was the highest and the proportion on the lower slope was the lowest. Larval emergence from acorns commenced just after acorns fell from the trees and lasted for 40–50 days, with peak emergence occurring from 24 to 32 days after acorn rain began. We conclude that insect‐infested acorn distribution in Q. liaotungensis shows spatial and temporal heterogeneity, and an early drop of infested acorns can be a short‐term defensive strategy against insect infestation.
Parasitism of mosquitoes (Diptera: Culicidae) by larval mites (Acari: Parasitengona) in Adelaide, South Australia
Authors: Williams Craig R , Proctor Heather C
Published: March 2003

Larval mites (Acari) from the cohort Parasitengona were collected from adult female mosquitoes captured in Adelaide, South Australia, from 1997 to 2000. Larvae from three families were identified: Arrenuridae, Hydryphantidae and Erythraeidae. Arrenurid larvae were associated with mosquitoes that use ground pools for larval habitat, while hydryphantids were associated with tree‐hole and container‐breeding species. Only a single erythraeid record was made. The overall prevalence of parasitism was very low (0.27% of 19 280 mosquitoes) and ranged from 0 to 5.6% for the 16 mosquito species collected. New mite–host records are presented.
Reduction in cricket (Orthoptera: Ensifera) populations along a gradient of sulphur dioxide from mining emissions in northern Australia
Authors: Hoffmann Benjamin D , Lowe Lyn M , Griffiths Anthony D
Published: March 2003

The impact of SO2 dry deposition from mining emissions on cricket abundance,

diversity and composition was investigated at Mount Isa in the semiarid tropics of

northern Australia. Seventy‐one sites were sampled, stratified at two levels: sulphur

deposition zones (high, medium, low, and background zones) and habitat (rocky ridge,

rocky plain and alluvial plain). The three habitats did not support distinctly different

cricket assemblages. Crickets responded to SO2 emissions, but impacts

were largely restricted to the high‐sulphur zone. Generalised linear modelling showed

significant reductions in the probability of presence in the high‐sulphur zone for

the three genera Eurepella, Salmanites and Endacusta, and the subfamily

Eneopterinae. In ordination space, the three high‐sulphur zone by habitat combinations

were clearly separated from all other combinations, and vector fitting of environmental

variables showed soil SO4 to be a primary correlative factor of this separation.

Crickets are sensitive to SO2 emissions and they appear to be a good indicator group in this context.
The clinical effects of spider bites in southern Tasmania
Authors: Woo Kathy Ml , Smart David R
Published: March 2003

Objectives: To analyse the clinical features and outcomes of patients with spider bites who presented to the Department of Emergency Medicine, Royal Hobart Hospital, Tasmania, Australia.

Methods: A retrospective study of all patients with an emergency department discharge diagnosis of confirmed spider bite during a 5 year period was performed.

Results: Twenty‐two cases were identified, 15 of which involved unidentified spiders. Most victims were in the 15–34 years age group and were bitten in the home. Identified spiders included: redback (Latrodectus hasselti), white‐tailed house (Lampona cylindrata), black house (Badumna insignis) and huntsman (Delena cancerides). Pain, swelling and erythema were the main presenting symptoms; main presenting signs were erythema, swelling, bite marks, local tenderness, lymphadenopathy and blistering. In 23% of cases, no clinical signs were detectable. Treatment consisted of antihistamines (36%) and antibiotics (32%). Four patients had signs consistent with necrotizing arachnidism; two of the four healed with hyperbaric oxygen after antibiotic treatment failed. Redback antivenom was administered to four patients. Three patients required in‐patient treatment for local complications.

Conclusions: Most spider bites presenting to Royal Hobart Hospital were uncomplicated; redback bites were uncommon. Treatment strategies were ill‐defined and microbiological specimens were taken infrequently. Patients’ tetanus immunization status was poorly documented. There is a need for a national register of spider bites in Australia.
Survey of management of fever without source in young children in Australasian emergency departments
Authors: Smith Brendon
Published: March 2003

Objective: To document the management of young children with fever without source presenting to emergency departments in Australia and New Zealand, and to document to what extent published guidelines are followed.

Method: A questionnaire survey was mailed to Directors of emergency departments.

Results: Variation in practice, by a number of measures including age ranges used, threshold temperature, investigations performed, antibiotic use and admission criteria was found. Half the departments did not have written management protocols which correlated with greater variation in practice within a department, compared with those that did have written management protocols. For children 3 to 36 months of age, in three of 23 departments (13%) antibiotics were routinely prescribed for fever without source.

Conclusions: Among emergency departments, there is variation in practice in the management of fever without source in infants and young children. Variation within departments is correlated with lack of written management guidelines. Antibiotic use is markedly less than recommended in published guidelines and clinical assessment is emphasized. It is proposed that published guidelines have not been incorporated into routine practice because evidence from clinical trials does not support the guidelines.
Near hanging
Authors: Adams Nick
Published: March 2003

Abstract

Objectives: To review the literature on near hanging, focusing on the pathophysiology, and relating this to the clinical features and management.

Methods: English language articles published in the past 15 years and major textbooks of emergency and forensic medicine were searched. Eight case series and six relevant single case reports were identified. Only articles concerned with non‐judicial near hanging were reviewed. Data concerning the incidence of cervical spine injury, laryngeal injury, pulmonary complications and mortality were extracted. Not the case series documented the presence or absence of all these factors, resulting in differing total patient numbers in each category. Unusual complications of near hanging were documented from case reports.

Results: Cervical spine injury occurred in four of 689 patients (0.6%). Pulmonary complications occurred in 15 of 133 patients (11%). The in‐hospital mortality rate was 23% (29 deaths of 128). No clinically significant laryngeal injuries were reported. Unusual complications documented included hyperthermia, status epilepticus, carotid artery dissection, subarachnoid haemorrhage and pneumoperitoneum.

Conclusions: Cervical spine injury, although uncommon, does occur in near hanging, and emergent airway management should take this into account. Laryngeal injury sufficiently severe to interfere with endotracheal intubation does not appear to occur. Cerebral oedema, aspiration pneumonia and acute respiratory distress syndrome are the commonest in‐hospital complications. Management of near hanging involves establishment of a safe airway, plus treatment of pulmonary and cerebral oedema along standard lines. In‐hospital mortality remains high.
Are too many head CT scans ordered in emergency departments?
Authors: Kelly Anne‐Maree , Kerr Debra
Published: March 2003

Objectives: The aims of this study were to: (i) characterize ordering of head computed tomography scans from the emergency department; (ii) determine the proportion of scans that yield an abnormal result; (iii) correlate results with clinical syndromes and neurological findings; and (iv) identify areas where a change in ordering practice may be warranted.

Method: Prospective case identification with detailed explicit review of clinical notes and radiological findings.

Results: Two hundred and thirty‐six cases were analysed. The rate of head computed tomography scans was 2.3% of all emergency department attendances. Of the scans, 21.6% were abnormal with the most common abnormalities being haemorrhage or infarction. Indications that correlated highly with abnormal scans were altered mental state (43.7%), focal weakness (36.7%), mild head injury (21.2%) and confusion (18.5%). Headache, transient ischaemic attack and seizure had low correlations with abnormal scans.

Conclusion: The results of this study suggest that the overall rate of head computed tomography scans ordered by the study emergency department was appropriate. It also supports the development of guidelines for the ordering of head computed tomography scans in patients with headache, seizure and transient ischaemic attack.
Australian and New Zealand 1997 thrombolysis audit
Authors: Mountain David , Jelinek George , O’Brien Debra , Ardagh Michael , Ieraci Sue , Lynch Dania , Jacobs Ian , Lopez Derrick
Published: March 2003

Objectives: To describe patterns of revascularization techniques in acute myocardial infarction in Australasia, particularly time to thrombolysis, site of delivery, patient demographics, revascularization rates and outcomes.

Methods: Seventy‐four Australasian emergency departments were surveyed. Data from 1997 were obtained on number of acute myocardial infarction patients, age, gender, time to revascularization, intracranial haemorrhage rate, mortality, location and rate of revascularization and angioplasty. Grouped data were analysed.

Results: Thirty‐three hospitals responded (44.6%). Many others could not supply data. Of 2930 acute myocardial infarction patients, 29% received thrombolysis and 5% angioplasty. Tertiary hospitals thrombolysed more in coronary care units (24.2% versus 8.8%), while non‐tertiary hospitals used emergency departments more (16.2% versus 5.9%). Average emergency department door‐to‐needle time was 49.4 min (median 38.6) versus 63.9 min (median 66.8) in coronary care units. More patients had streptokinase than tissue‐type plasminogen activator. Inferior myocardial infarction accounted for 58% of cases. Primary angioplasty commenced on average 61.5 min (median 69.2) after arrival.

Conclusions: Australasian revascularization procedure rates, times, mortality and intracranial haemorrhage rates are similar to internationally published values. Thrombolysis starts sooner if given in emergency departments. Hospitals thrombolysing patients in coronary care units should consider emergency department thrombolysis if median times are greater than 50 min.
QUEST: Questionnaire relating to patients’ Understanding and Expectations of their Symptoms and Treatment
Authors: Bartley Bruce , Cameron Peter
Published: March 2003

Objectives: To survey patients’ perceptions of illness and their expectations of the emergency department visit in a major tertiary‐referral teaching hospital and to compare these responses with the doctors’ assessment in a major tertiary‐referral teaching hospital.

Method: A two‐part survey was conducted. Patient questions focused on patient perception of illness severity, and expectation of process and outcome. Doctor questions focused on the severity of illness and the advice given.

Results: Pre‐consultation: Of 141 patients, 94 (67%) were concerned that they were suffering from something serious or dangerous. Eighty‐three of 145 patients (57%) expected an explanation and/or reassurance. Eighty‐four of 145 patients (58%) expected investigation. Twenty‐seven of 135 patients (20%) expected admission to hospital. Post‐consultation: 119/126 patients (94%) who were given an explanation stated that they understood their illness. One hundred and thirteen of 122 patients (93%) felt reassured on departure.

Conclusions: In this group of patients, fear of a dangerous or life‐threatening condition not borne out in the doctors’ assessment is common. Present clinical practice, including explanation and reassurance based on clinical and investigation findings, appears sufficient to meet patient expectations.
Chronic meningococcaemia
Authors: Teoh Ben , Williams Aled
Published: March 2003

Meningococcal infection usually presents as a severe illness with septicaemia, cardiovascular collapse and a purpuric rash. Less commonly, it presents in a chronic form with an intermittent course over a number of weeks. Chronic meningococcaemia may mimic other conditions, such as viral illness or autoimmune disease. Early diagnosis of chronic meningococcaemia is essential because it may progress into the more familiar acute form. Emergency physicians need to be aware of the disease and its clinical features so that appropriate interventions can be made when a patient presents with a suggestive clinical picture. In this article, we present a case of chronic meningococcaemia that was seen three times in an emergency department before the correct diagnosis was made. We will also review the pathophysiology and the clinical features that may aid in the early diagnosis of this unusual condition.
Essential role of prehospital care in the optimal outcome from major trauma
Authors: Hodgetts Tim J , Smith Jason
Published: March 2003

Prehospital care for major trauma victims is a balance of timely delivery to definitive care and appropriate intervention to maximize probability of survival. In the development of advanced, organized prehospital care systems, the evidence for the benefit of individual interventions has been limited and contradictory. Leading controversies reviewed are: the place of advanced life support, the role of doctors compared with paramedics, the optimal advanced airway adjunct, the role of intravenous fluids in serious injury, and the value of prehospital cardiopulmonary resuscitation following traumatic cardiac arrest. International differences in trauma epidemiology are discussed. The identification of prehospital care as the weak link within a trauma system is highlighted.
Establishing rudimentary health‐care facilities in East Timor
Authors: Galvin G Michael
Published: March 2003

The former Portuguese colony of East Timor was forcibly absorbed into the Republic of Indonesia in 1975. An armed East Timorese resistance movement maintained a fight for independence for the next quarter of a century. The Indonesian Government allowed a plebiscite of the population in August 1999, the result of which was strongly in favour of independence. Following the poll, there was an outbreak of extreme violence and the structure of the country was virtually destroyed. The Indonesian Government invited a multinational force to restore order. This report is of the medical work conducted while serving in a multifunction non‐government organization in East Timor in the post‐conflict environment. The work includes developing a tuberculosis clinic, conducting refugee medicine at the border crossing point and establishing a rudimentary health‐care system based on a primary‐care model. A background in emergency medicine is very useful in situations such as this, where improvisation becomes a core skill.
Suspected subarachnoid haemorrhage with a negative CT head scan: What next?
Authors: Foot Carole , Merfield Eve
Published: March 2003

The current recommended ‘next investigation’ for patients with a suspected subarachnoid haemorrhage and a negative non‐contrast computed tomography head scan, is a lumbar puncture. The cerebrospinal fluid obtained at lumbar puncture may be examined for the presence of blood and xanthochromia. Xanthochromia may be assessed by macroscopic examination or by spectrophotometry. Total red cell count and the three‐tube test have poor sensitivity and specificity as investigations for diagnosing subarachnoid haemorrhage. Macroscopic examination for xanthochromia is unreliable, with a risk of false‐negative results. Spectrophotometric examination for xanthochromia is associated with false positive results. The use of cerebrospinal fluid derivative spectroscopy and D‐Dimer testing using an enzyme‐linked immunosorbent assay need further evaluation. In the future, computed tomography angiography or magnetic resonance angiography may change current practice. Until then, all patients should be advised to have a lumbar puncture. A cerebrospinal fluid specimen obtained at least 8 h after the onset of headache and analysed for xanthochromia via spectrophotometry has the best chance of placing the patient in the lowest possible risk category. The emergency physician must be aware of the methods of cerebrospinal fluid analysis used locally.