bluuebunny/crossref_metadata_2025 huggingface dataset:
Randomized controlled trial of nebulized adrenaline in acute bronchiolitis
Authors: Hariprakash Suriyanarayanapillai , Alexander John , Carroll Will , Ramesh Pavanasam , Randell Tabitha , Turnbull Frances , Lenney Warren
Published: December 2004

Use of both l‐epinephrine and racemic epinephrine (adrenaline) has improved clinical symptoms and composite respiratory scores in acute bronchiolitis. The objective of this randomized double‐blind placebo‐controlled study was to assess whether there was sufficient improvement in clinical state to reduce hospital admissions. Seventy‐five infants aged 1 month to 1 year with a clinical diagnosis of acute bronchiolitis were treated with either 2 ml of 1:1000 nebulized adrenaline or 2 ml of nebulized normal saline administered after baseline assessment and 30 min later. Clinical respiratory parameters were recorded at 15‐min intervals for a period of 2 h following the baseline assessment. Admission to hospital was the primary end‐point and changes in respiratory parameters were secondary end‐points. Fifty percent (19/38) of infants treated with adrenaline were discharged home compared with 38 percent (14/37) of those treated with saline. This 12 percent reduction in rate of admission is not statistically significant (95% CI of difference: −10% to 35%). There was no difference between treated and placebo groups in respiratory rate, oxygen saturation, heart rate or a composite respiratory distress score at 30, 60 or 120 min post‐treatment. In this study, nebulized epinephrine did not confer a significant advantage over nebulized saline in the emergency room treatment of acute bronchiolitis.
Natural exposure to Alternaria spores induces allergic rhinitis symptoms in sensitized children
Authors: Andersson Morgan , Downs Sara , Mitakakis Teresa , Leuppi Jörg , Marks Guy
Published: December 2004

Allergic rhinitis is associated with exposure to inhaled allergens. Allergic sensitization to the fungus Alternaria is common, especially in warm climates, but the relevance of sensitization to Alternaria in the generation of rhinitis has not been elucidated. The aim of this study was to determine whether natural exposure to Alternaria induces rhinoconjuctivitis symptoms in Alternaria‐sensitized children. Symptoms of rhinoconjuctivitis in 132 atopic (measured by skin prick tests) children (aged 7–12 years) in inland New South Wales Australia were measured using parent‐completed questionnaires in summer and winter 1998. Airborne concentrations of Alternaria spores and grass pollen were measured throughout the study period using a Burkard volumetric trap. The relation between airborne concentrations of Alternaria spores and symptoms of rhinoconjunctivitis was examined using Wilcoxon's matched pairs signed ranked test and generalized estimating equations. The proportion of children atopic to Alternaria reporting symptoms of rhinitis was significantly higher in the summer, when airborne concentrations of Alternaria were high, than in the winter, when airborne concentrations were low (66.2% vs. 38.2% for nasal symptoms at night, p = 0.0001, 70.6% vs. 51.52% for nasal symptoms during the day, p = 0.02). The proportion of children using anti‐allergic treatment was also higher in summer than in winter (anti‐allergic medication for the nose 39.7% vs. 17.7%, p = 0.0003). A strong correlation between airborne concentrations of grass pollen and Alternaria was found (R = 0.94, p < 0.001). However, when all children atopic to ryegrass were excluded from the analyses, significant associations between symptoms and season remained. We conclude that exposure to Alternaria spores may be an important cause of allergic rhinoconjunctivitis.
Renal retransplantation of children: Is a policy ‘first cadaver donor, then live donor’ an acceptable option?
Authors: De Meester J. , Smits J. M. A. , Offner G. , Persijn G. G.
Published: December 2004

Abstract: Retransplantation is often a necessity for children with end‐stage renal disease (ESRD), as kidney graft survival is still not infinite. If a suitable live donor is present, the current policy is to use the live donor first, in order to obtain excellent long‐term outcome and to prevent human leucocyte antigen (HLA) sensitization. Data from the Eurotransplant International Foundation were analyzed to determine whether the sequence, first a cadaveric donor then a live donor, is acceptable. Between January 1 1983 and December 31 1995, 1305 children received a first renal transplant; 269 of them had a second transplant during the same period. Follow‐up of at least 1 yr was available. Categories were made according to the sequence of renal donor source: 217 patients were classified as first cadaver and second cadaver (1cad‐2cad) transplant, 26 as first cadaver and second live (1cad‐2liv) donor transplant, 23 as first live donor and second cadaver (1liv‐2cad) transplant and three patients had two subsequent live donor transplants (1liv‐2liv). When a live donor transplant was carried out, either first or second, the donor age was always higher, and the chance of a pre‐emptive transplantation or short stay on dialysis was higher, compared with a cadaver transplant. The re‐graft survival rate of the ‘1cad‐2liv’ was better than the ‘1cad‐2cad’ and ‘1liv‐2cad’ transplants. At 5 yr, the survival was 76%, 49%, and 61%, respectively. These data suggest that, when a suitable live donor is not available for a first transplantation owing to medical and/or familial reservations, a policy of ‘first a cadaver donor then a live donor’ transplantation is a viable option and should even be promoted. The pre‐emptive stage of the second transplant, probably with a live donor, is additionally advantageous.
Comparison of polyclonal induction agents in pediatric renal transplantation
Authors: Brophy Patrick D. , Thomas Susan E. , McBryde Kevin D. , Bunchman Timothy E.
Published: December 2004

Abstract:Collective pediatric data suggest that anti‐T‐cell induction therapy with polyclonal antibodies improves the outcome of both short‐ and long‐term renal allograft survival. Polyclonal agents, including thymoglobulin (Thy), a rabbit anti‐thymocyte globulin; Minnesota (horse) anti‐lymphoblast globulin (ALG); and ATGAM, a horse anti‐thymocyte globulin (ATG), all suppress B and T cells. While no specific T‐cell subset marker exists to measure the adequacy of immunosuppression with polyclonal induction, flow cytometric analysis has been used to evaluate the suppression of CD3, CD4, and CD8 cells. Thy is currently undergoing pediatric trials at our center, and we have utilized ATG and ALG in previous pediatric induction protocols. ALG (20 mg/kg/day) and ATG (15 mg/kg/day) were administered over 10 days, whereas Thy (2 mg/kg/day) was given over 5 days. All inductions were accompanied by preoperative intravenous solumedrol (10 mg/kg) followed by oral prednisone (2 mg/kg/day) with taper. Preoperative (1.5 mg/kg/day) and post‐operative (2 mg/kg/day) azathioprine was administered to patients receiving ALG or ATG. Mycophenolate mofetil (MMF) (1200 mg/m2/day) was given to the patients receiving Thy. Post‐operative cyclosporin A (CsA) (14 mg/kg/day) was started (for all groups) once renal function permitted (creatinine < 50% of baseline with brisk urine output) (trough goal 150–250 ng/mL via HPLC). Values for CD3, CD4, and CD8 T cells were determined by flow cytometry in 2–18‐yr‐old renal transplant recipients, comparing the polyclonal induction agent utilized [Thy (n = 8), mean age 9.7 ± 2.3 yr; ATG (n = 13), mean age 10.1 ± 4.1 yr; and ALG (n = 9), mean age 9.3 ± 3.7 yr] over days 2–10 post‐induction. Data were expressed as the average percentage of cells remaining relative to the baseline T‐cell subsets (day 1 = 100%), because of the large age variation present in basal T‐cell subset values. The flow cytometric data suggest that 5 days of Thy appears to give an equal or greater peripheral blood T‐cell suppression by day 10 than a 10‐day course of either ATG or ALG.
Oral administration of tacrolimus in the presence of jejunostomy after liver transplantation
Authors: Hasegawa Toshimichi , Nara Keigo , Kimura Takuya , Soh Hideki , Sasaki Takashi , Azuma Tatsuo , Okada Akira
Published: December 2004

Abstract:The feasibility of oral administration of tacrolimus in the presence of an intestinal stoma after liver transplantation (LTx) has not been adequately demonstrated. A 10‐month‐old girl underwent LTx with biliary reconstruction using a Roux‐en Y loop. She developed intestinal perforation and underwent a jejunostomy at 40–50 cm distal to the jejunojejunostomy of the Roux‐en Y loop on day 8 post‐LTx. Tacrolimus was given twice daily via a nasogastric tube or orally; the initial dose of tacrolimus was 0.10 mg/kg/day. Until the time of intestinal perforation, the trough level of tacrolimus ranged from 13.0 to 19.6 ng/mL. The dose‐normalized trough concentration (DNTC) of tacrolimus ranged from 130 to 196 ng.kg.daypermg.mL (control: 80–145 ng.kg.daypermg.mL). For a 2‐week period when the patient was septic, the tacrolimus dose was reduced to 0.05 mg/kg/day, with a subsequent trough level of 3.6–5.1 ng/mL (DNTC: 72–102 ng.kg.daypermg.mL). After 3 weeks, the dose was increased to 0.175 mg/kg/day with the disappearance of infection; the trough level ranged from 8.5 to 9.7 ng/mL with a peak level of 26.3 ng/mL (DNTC: 48.5–55.4 ng.kg.daypermg.mL). After the initiation of oral feeding, the dose was slightly increased to 0.20 mg/kg/day with the trough level ranging from 8.1 to 9.8 ng/mL (DNTC: 40.5–49 ng.kg.daypermg.mL). After closure of the jejunostomy, the dose of tacrolimus was reduced to 0.075 mg/kg/day to maintain the same trough level (7.9–9.1 ng/mL) and the DNTC ranged from 105 to 121 ng.kg.daypermg.mL. In conclusion, oral administration of tacrolimus may achieve the therapeutic level, even in the presence of jejunostomy after LTx, although the bioavailability is decreased.
Ambulatory blood pressure monitoring in pediatric renal transplantation
Authors: Mitsnefes Mark M. , Portman Ronald J.
Published: December 2004

Abstract: Over last two decades ABPM has evolved from a research device to an established and valuable clinical tool for BP evaluation. More than 10 yrs ago ABPM was introduced to pediatrics and since that time, its importance has been increasing in the management of hypertension in children and adolescents. This review summarizes the information gathered from the studies of ABPM in adult and pediatric patients with renal transplants. We will review the importance of hypertension in this patient subset, discuss the advantage of ABPM over CBP and focus on specific abnormalities and clinical significance of ABPM in renal transplant recipients.
Tolerance of crop plants to oxygen deficiency stress: fermentative activity and photosynthetic capacity of entire seedlings under hypoxia and anoxia
Authors: Mustroph Angelika , Albrecht Gerd
Published: December 2004

The study investigates the reactions of rice, wheat and maize to anoxia (plants without access to oxygen) and hypoxia (roots with very limited access to oxygen). We studied the adaptations of these intact crop plants because they are known to differ widely in their tolerance to oxygen deficiency. In hypoxia, there was an accumulation of sugars, especially in wheat and maize, although both flood‐sensitive species significantly increased the activities of fermentative and glycolytic enzymes, clearly more than in rice. In rice, avoiding an oxygen limitation due to the effective aeration system (30% of root cross‐sectional area) may have accounted for only a minor metabolic reaction to hypoxia. In anoxia, maize and wheat quickly lost viability and nearly all photosynthetic capacity, while most rice leaves stayed turgid and green, losing only 50% of the photosynthetic capacity. A strong metabolic arrest under anoxia was obvious for the sucrolytic, glycolytic and fermentative enzymes in all tested species, but was most pronounced in rice. Of the 14 enzymes studied, rice showed the lowest activity increase in hypoxia for 11 enzymes, and the strongest activity decrease in anoxia for 8 enzymes. However, rice was able even under anoxia to keep a 1/4 of the ATP level of the aerated control, while it was at the detection limit in maize and wheat. It appears that in anoxic rice, the switch to metabolic dormancy and maintenance of basic shoot meristems diminishes the needs for energy and substrate. Additionally, rice already has lower sugar demand under hypoxia, and sugar supply appears to be sustained under anoxia by a functioning anaerobic amylase and by the photosynthetically active shoot.
Dark chilling effects on soybean genotypes during vegetative development: parallel studies of CO2 assimilation, chlorophyll a fluorescence kinetics O‐J‐I‐P and nitrogen fixation
Authors: Van Heerden Philippus D. R. , Tsimilli‐Michael Merope , Krüger Gert H. J. , Strasser Reto J.
Published: December 2004

The effects of dark chilling on CO2 assimilation, chlorophyll a fluorescence kinetics and nitrogen fixation were compared in two Glycine max (L.) Merr. genotypes. The aim was to elucidate the mechanisms by which photosynthesis was inhibited as well as identification of selection criteria for dark chilling tolerance. Seedlings were dark chilled (8°C) for 9 consecutive nights but kept at normal day temperatures (28°C). CO2 gas exchange analysis indicated that photosynthesis in Maple Arrow was inhibited largely as a result of stomatal limitation, while in Fiskeby V, it indicated inhibition of the mesophyll reactions. Increased intercellular CO2 concentration and decreased carboxylation efficiency suggested loss of Rubisco activity in Fiskeby V, although no effect on the KM (CO2) of Rubisco was observed. Quantification and deconvolution of the Chl a fluorescence transients into several phenomenological and biophysical parameters (JIP‐test) revealed large genotypic differences in the response of PSII to dark chilling. These parameters differentially changed in the two genotypes during the progression of the chilling treatment. Among them, the performance index, reflecting several responses of the photochemical apparatus, provided the best preliminary overall assessment of the genotypes. In contrast, the quantum yield of primary photochemistry ϕPo (FV/FM) was quite insensitive. The recovery of most of the JIP‐test parameters in Maple Arrow after 6 and 9 nights of dark chilling was a major genotypic difference. Genotypic differences were also observed with regard to the ureide response and N2 fixation appeared to be more sensitive to dark chilling than CO2 assimilation. The JIP‐test provided information consistent with results derived from CO2 assimilation and N2 fixation studies suggesting that it can substitute the much more time‐consuming methods for the detection of chilling stress and can well satisfy the requirements of a rapid and accurate screening method.
Effect of various temperatures on phosphatidylglycerol biosynthesis in thylakoid membranes
Authors: Xu Yi‐Nong , Wang Ze‐Neng , Jiang Gui‐Zhen , Li Liang‐Bi , Kuang Ting‐Yun
Published: December 2004

Lipid unsaturation, the major factor to maintain thylakoid membrane fluidity, is affected by temperature. In this work, we analysed the molecular species composition of phosphatidylglycerol (PG) in thylakoid membranes during spinach (Spinacia oleracea) and squash (Cucurbita pepo) cotyledon growth to investigate how the growth temperature affects the PG biosynthesis. Of the 10 molecular species detected, temperature affected mainly the relative content of molecular species containing linolenic acid (18:3) and those containing palmitic acid (16:0) at the sn‐1 position of glycerol backbone. Lowering the temperature induced an increase in the former and a decrease in the latter. The relative content of molecular species containing 18:3 or 16:0 at the sn‐1 position of the glycerol backbone were correlated with temperature. Our results indicate that the substrate selectivity of the glycerol‐3‐phosphate acyltransferase (GPAT) in chloroplasts towards 16:0 or oleic acid (18:1) and the activity of fatty acid desaturases are greatly affected by temperature. In addition, changes in the relative content of PG molecular species induced by variations in growth temperature depended mainly on the substrate selectivity of GPAT.
Differential expression of the LePS2 phosphatase gene family in response to phosphate availability, pathogen infection and during development
Authors: Stenzel Irene , Ziethe Kathrin , Schurath Joerg , Hertel Silvia C. , Bosse Dittmar , Köck Margret
Published: December 2004

In this study, we report the cloning of the three‐member LePS2 gene family of acid phosphatases via subtractive screening of a cDNA library of Pi‐starved cultivated tomato cells (Lycopersicon esculentum Mill. cv. Lukullus). As members of the plant Pi‐starvation response, LePS2 genes were tightly regulated in cultivated cells and tomato seedlings by Pi availability. The LePS2 enzymes which are most likely expressed in the cytoplasma could be involved in processes that are accompanied by degradation of phosphorylated organic substrates. Independently from exogenous phosphate supply LePS2 expression was detected in tomato endosperm during germination. LePS2 genes were differentially induced after infection with the bacterial pathogen Pseudomonas syringae and in the early stages of flower development. Using RT–PCR it was found that the gene LePS2B was the most abundant transcript in phosphate‐depleted cells, but a reduced expression was determined in floral buds and it was not found during pathogen interaction. In this respect, it is interesting that the promoter sequences of the LePS2 genes are also divergent. LePS2 gene products may have functions in developmental processes which are restricted to distinct plant tissues or cell types.
Effects of long‐term chilling on growth and photosynthesis of the C4 gramineae Paspalum dilatatum
Authors: Cavaco Ana M. , Da Silva Anabela Bernardes , Arrabaça Maria Celeste
Published: December 2004

Dallis grass (Paspalum dilatatum Poir.) is a C4/NADP‐ME gramineae, previously classified as semi‐tolerant to cold, although a complete study on this species acclimation process under a long‐term chilling and controlled environmental conditions has never been conducted. In the present work, plants of the variety Raki maintained at 25/18°C (day/night) (control) were compared with plants under a long‐term chilling at 10/8°C (day/night) (cold‐acclimated) in order to investigate how growth and carbon assimilation mechanisms are engaged in P. dilatatum chilling tolerance. Although whole plant mean relative growth rate (mean RGR) and leaf growth were significantly decreased by cold exposure, chilling did not impair plant development nor favour the investment in biomass below ground. Cold‐acclimated P. dilatatum cv. Raki had a lower leaf chlorophyll content, but a higher photosynthetic capacity at optimal temperatures, its range being shifted to lower values. Associated with this higher capacity to use the reducing power in CO2 assimilation, cold‐acclimated plants further showed a higher capacity to oxidize the primary stable quinone electron acceptor of PSII, QA. The activity and activation of phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) and ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco; EC 4.1.1.39) were not significantly affected by the long‐term chilling. Cold‐acclimated P. dilatatum cv. Raki apparently showed a lower transfer of excitation energy from the light‐harvesting complex of photosystem II to the respective reaction centre and enhancement of radiationless energy‐dissipating mechanisms at suboptimal temperatures. Overall, long‐term chilling resulted in several effects that comprise responses with an intermediate character of both chilling‐tolerant and –sensitive plants, which seem to play a significant role in the survival and acclimation of P. dilatatum cv. Raki at low temperature.
The temperature‐dependent accumulation of Mg‐protoporphyrin IX and reactive oxygen species in Chlorella vulgaris
Authors: Wilson Kenneth E. , Sieger Stephen M. , Huner Norman P. A.
Published: December 2004

Photosynthetic organisms undergo photoacclimation in response to changes in environmental conditions to maximize energy production and at the same time protect the light‐sensitive pigments and proteins from excess light. Low temperature and high irradiance both cause the electron transport chain to become more reduced which can result in the production of damaging reactive oxygen species. In the unicellular green alga Chlorella vulgaris Beij., light and temperature regulate light‐harvesting protein accumulation via the redox state of the plastoquinone pool. To investigate temperature‐dependent factor (s) regulating light‐harvesting protein accumulation we measured the abundance of chlorophyll biosynthetic precursors and reactive oxygen species production in C. vulgaris cells acclimated to a series of growth conditions. We observed that Mg‐protoporphyrin accumulates in response to low temperature, but its abundance does not correlate with light‐harvesting protein levels. Reactive oxygen levels measured under the same growth conditions strongly correlated with light‐harvesting protein levels. Therefore, we suggest that reactive oxygen species may act as part of both a temperature‐ and irradiance‐dependent signalling mechanism in the regulation of light‐harvesting protein accumulation in response to growth conditions.
Stress response, cell death and signalling: the many faces of reactive oxygen species
Authors: Mahalingam Ramamurthy , Fedoroff Nina
Published: December 2004

Plants respond to pathogens and abiotic stresses by transient increases in the production of reactive oxygen species (ROS) and ion fluxes, which activate both local programmed cell death and systemic increases in stress‐ and pathogen‐resistance. The present essay explores the emerging complexity of the multiple roles that ROS play in intra‐ and intercellular communication in both stressed and unstressed organisms.
The ability of abaxial and adaxial epidermis of sun and shade leaves to attenuate UV‐A and UV‐B radiation in relation to the UV absorbing capacity of the whole leaf methanolic extracts
Authors: Liakoura Vally , Bornman Janet F. , Karabourniotis George
Published: December 2004

The UV‐absorbing capacity (measured as A310 cm−2 and A365 cm−2 or AUVR cm−2) of the shade leaves of four representative evergreen sclerophylls of the Mediterranean region (Quercus coccifera, Q. ilex, Arbutus andrachne and A. unedo) was considerably lower than the corresponding one of sun leaves of the same species. However, fibre optic microprobe measurements showed that adaxial as well as abaxial epidermis of shade leaves of all examined plants, except abaxial epidermis of A. andrachne, were almost as effective as the corresponding ones of the sun leaves in screening out most of the incident UV‐B radiation. There is probably a threshold, under which the concentration of the UV‐B absorbing compounds in the protective tissues is not furthermore reduced, in spite of the low levels of the stress factor (UV‐B radiation) in the environment. On the other hand, the ability of both abaxial and adaxial epidermis to attenuate UV‐A radiation, except of adaxial leaf epidermis of Quercus species, depended on the UV absorbing capacity of the whole‐leaf extracts, with different correlation patterns between the two Quercus species and the two Arbutus species. This could be explained by the fact that shade leaves showed not only quantitative, but also qualitative differences (higher A310/A365 ratio) in the absorbance of their methanolic extracts compared to these of sun leaves. The results of the present study showed that we should not always correlate the depth of penetration of UV radiation into sun and shade leaves according to the corresponding UV absorbing capacity of the whole leaf methanolic extracts, without taking into account all the anatomical, developmental and biochemical (such as different composition and distribution of the UV‐absorbing compounds among the different protective tissues) peculiarities of the leaves of each species.
Molecular cloning of cDNAs for three tau‐type glutathione S‐transferases in pumpkin (Cucurbita maxima) and their expression properties
Authors: Fujita Masayuki , Hossain Mohammad Z.
Published: December 2004

cDNAs of three major glutathione S‐transferases (GSTs), Puga, Pugb and Pugc, in 2,4‐D‐treated pumpkin (Cucurbita maxima Duch.) callus were individually obtained through immuno‐screenings with corresponding antisera from a pumpkin cDNA library. Comparison of the predicted protein sequences with ones of other plant GSTs reported previously and recognition of the presence of a single intron in each genomic gene indicated that they could be classified into tau‐type GST group. Hence, Puga, Pugb and Pugc were named CmGSTU1, CmGSTU2 and CmGSTU3, respectively. Expression of the GSTs in various organs of pumpkin plants, and in hypocotyls of seedlings under various stress conditions were examined by Western blotting and Northern blotting analyses. CmGSTU1 tended to be expressed more in fully expanded mature organs, and CmGSTU2 seemed to be expressed preferentially in leaves and petioles. CmGSTU1 and CmGSTU2 were induced by dehydration. CmGSTU1 was also induced by high temperature stress. In this study, the expression pattern of CmGSTU3 could not be determined because the contents were too low to detect with the antiserum. After 2,4‐d treatment, GST activity in the pumpkin callus increased rapidly until day one and then slowly increased at a constant rate up to day 6. The increase seemed to be dependent on post‐transcriptional enhancement as well as transcriptional induction.
A biological spectral weighting function for ozone depletion research with higher plants
Authors: Flint Stephan D. , Caldwell Martyn M.
Published: December 2004

Biological spectral weighting functions (BSWF) play a key role in assessing implications of stratospheric ozone reduction. They are used to calculate the increase in biologically effective solar UV radiation due to ozone reduction (radiation amplification factor, RAF), assess current latitudinal gradients of solar UV radiation, and compare solar UV radiation with that from lamps and filters used in experiments. As a basis for a BSWF, we developed an action spectrum for growth responses of light‐grown oat (Avena sativaL. cv. Otana) seedlings exposed to narrowband UV radiation from a large double water‐prism monochromator. Five UV wavelength peaks were used (275, 297, 302, 313 and 366 nm) in the absence of any visible radiation. Growth responses were measured from 1 to 10 days after the treatments. At all these wavelengths, the UV radiation inhibited height growth, including the height at which the first leaf separated from the stem. Radiation at all wavelengths used, except the one UV‐A wavelength, promoted the length of the second leaf. The resulting action spectrum closely resembles the commonly used generalized plant response function except that it indicates continued sensitivity into the UV‐A region. When used as a BSWF for the ozone depletion problem, this new function for plant growth would suggest substantially less impact of ozone depletion because it results in only a modest increment of biologically effective UV for a given level of ozone depletion (a lower RAF). Yet this new BSWF also suggests that experimental treatments based on previous BSWF with less emphasis on the UV‐A may have resulted in simulations of less pronounced ozone depletion than intended. The validity of this new BSWF with UV‐A sensitivity, designated the UV plant growth weighting function, was verified in field experiments as described in the companion paper.
When do herbivores affect plant invasion? Evidence for the natural enemies and biotic resistance hypotheses
Authors: Maron John L. , Vilà Montserrat
Published: December 2004

Two venerable hypotheses, widely cited as explanations for either the success or failure of introduced species in recipient communities, are the natural enemies hypothesis and the biotic resistance hypothesis. The natural enemies hypothesis posits that introduced organisms spread rapidly because they are liberated from their co‐evolved predators, pathogens and herbivores. The biotic resistance hypothesis asserts that introduced species often fail to invade communities because strong biotic interactions with native species hinder their establishment and spread. We reviewed the evidence for both of these hypotheses as they relate to the importance of non‐domesticated herbivores in affecting the success or failure of plant invasion.  To evaluate the natural enemies hypothesis, one must determine how commonly native herbivores have population‐level impacts on native plants. If native herbivores seldom limit native plant abundance, then there is little reason to think that introduced plants benefit from escape from these enemies. Studies of native herbivore‐native plant interactions reveal that plant life‐history greatly mediates the strength with which specialist herbivores suppress plant abundance. Relatively short‐lived plants that rely on current seed production for regeneration are most vulnerable to herbivory that reduces seed production. As such, these plants may gain the greatest advantage from escaping their specialist enemies in recipient communities. In contrast, native plants that are long lived or that possess long‐lived seedbanks may not be kept “in check” by native herbivores. For these species, escape from native enemies may have little to do with their success as exotics; they are abundant both where they are native and introduced.  Evidence for native herbivores providing biotic resistance to invasion by exotics is conflicting. Our review reveals that: 1) introduced plants can attract a diverse assemblage of native herbivores and that 2) native herbivores can reduce introduced plant growth, seed set and survival. However, the generality of these impacts is unclear, and evidence that herbivory actually limits or reduces introduced plant spread is scarce. The degree to which native herbivores provide biotic resistance to either exotic plant establishment or spread may be greatly determined by their functional and numerical responses to exotic plants, which we know little about. Generalist herbivores, through their direct effects on seed dispersal and their indirect effects in altering the outcome of native–non‐native plant competitive interactions, may have more of a facilitative than negative effect on exotic plant abundance.
The role of species richness for recruitment in a seminatural grassland
Authors: Franzén Daniel
Published: December 2004

I examined two aspects of how recruitment is influenced by species richness in a seminatural grassland: effects of species richness among colonisers in a seed mixture, and effects of species richness, ramet density, grass and moss cover in the colonised vegetation. The results suggest that recruitment is higher in more species‐rich seed mixtures (for three of the four target species: Anthyllis vulneraria, Centaurea jacea, Filipendula vulgaris and Primula veris). Average recruitment of the target species was negatively related to ramet density in the colonised vegetation, but not affected by grass or moss cover. The results imply that mechanisms other than interspecific competition among species are important in structuring the community during the recruitment phase. The negative effects of ramet density and the positive effects of species richness may be a result of strong intra‐specific competition, or species‐independent competition in combination with diversity effects enhancing microsite variability.
Population dynamics of host‐parasite interactions in a cockroach‐oxyuroid system
Authors: Müller‐Graf C. D. M. , Jobet E. , Cloarec A. , Rivault C. , Baalen M. van , Morand S.
Published: December 2004

Host‐parasite interactions of an urban cockroach,Blattella germanica, and its oxyuroid parasite,Blatticola blattae, were investigated. Life history data of host and parasites were collected under laboratory conditions. These data were used to model the effect of the parasite on the population dynamics of the host in order to understand the parasite's impact on the host population. The aggregation of parasites within a host was under‐dispersed. Hosts normally were found to be infected with only one male and one female and rarely two or three. However, the primary sex ratio after hatching was 1.1 (males/females). Female parasite longevity equalled the life span of its host.B. blattaehad a significant impact on the survival rate of the cockroach larvae and their time to reach maturity, but no effect on the survival rate of the adults. Infected host females produced fewer first oothecae than uninfected ones. Using the population parameters a simple model was developed to estimate the parasite's effect on the population dynamics of its host. According to the model the parasite suppresses the cockroach populations by ca 11%. Hence, the effect of the parasite does not appear strong enough to be used as a biological control agent by itself.
Sources of variability in plant resistance against insects: free caterpillars show strongest effects
Authors: Kaitaniemi Pekka , Ruohomäki Kai
Published: December 2004

Tests with herbivorous animals have shown great variability in foliage quality within individual plants. This may be a product of plant architecture and microclimate as well as a specific response to herbivory. We tested the level of constitutive and herbivore‐induced resistance within the canopy of mountain birch (Betula pubescensssp.czerepanovii) stems of different age, using shoots with different architectural position, function and age. We tested foliage both with uncaged larvae ofEpirrita autumnatafeeding freely on foliage and with growth trials in the laboratory. The only indication of systematic within‐tree variability was low consumption by third instar larvae growing on long shoot leaves. This may protect long shoots that would suffer from reduced growth if their first leaves were consumed at an early stage of development. Stem age and architecture did not contribute to within‐tree variation and the effects induced by herbivory were similar throughout the tree. A small number of caterpillars was sufficient to elicit responses in larval growth or consumption. This suggests that the presence of caterpillars may act as a cue of increased risk of future herbivory for mountain birch attacked byE. autumnatawith poor mobility and regular outbreaks. Previous defoliation and young age of stems increased the disappearance rate of free larvae. The effect of defoliation suggests that induced resistance may act to prevent future buildup ofE. autumnatapopulations. The small size and simple canopy architecture of young stems may in turn increase the disappearance rate by increasing the probability of predators finding prey. This may partly explain the low vulnerability of young mountain birch forests toE. autumnataoutbreaks. Overall, changes in the disappearance rate were greater than changes in larval growth and consumption. This suggests that tests in the laboratory or inside cages may underestimate the efficacy of induced resistance against herbivores.
Competition coefficients in a marine epibenthic assemblage depend on spatial structure
Authors: Dunstan Piers K. , Johnson Craig R.
Published: December 2004

We investigated the importance of the spatial context of interactions in a multispecies marine epibenthic assemblage with respect to the outcomes of interspecific interactions, neighbour‐specific growth rates, and the dynamics of spatial and mean‐field models of the system. We compared the outcomes of interactions and overgrowth rates of pair‐wise combinations of species in spatially simplified contrived interactions with the same combinations in an unmanipulated assemblage. While estimates of neighbour‐specific growth rates were similar in both sets of interactions, the probability of a species winning a particular interaction was strongly dependent on whether the interaction was contrived or occurred in the unmanipulated assemblage. The dynamics of a spatial model and its mean‐field equivalent parameterised from estimates of interaction outcome and neighbour‐specific growth from contrived interactions were significantly different to the dynamics of models based on estimates of interaction outcome and neighbour‐specific growth obtained from non‐manipulated assemblages. Differences in the dynamics of models based on parameters from unmanipulated and contrived interactions are primarily due to differences in outcomes of interspecific interactions, while fluctuations in growth rates contribute to the variability around these dynamics. Our results suggest that conclusions about interspecific interactions and community dynamics examined in simplified spatial associations (e.g. in manipulative experiments) is likely to be limited to assemblages with a similarly simplified spatial structure, which is an unlikely occurrence in nature.
Integrating methods that investigate how complementarity influences ecosystem functioning
Authors: Petchey Owen L.
Published: December 2004

Separating the mechanisms that influence ecosystem functioning has been a goal of recent high profile experiments. Integrating the various experimental and analytical methods that attempt this goal across terrestrial and aquatic ecosystems, as well as careful definition of ‘complementarity’, produces novel insights and valuable lessons about new directions for research. (1) Experimental designs differ in temporal scale and whether standing stock or another ecosystem process was the response variable. (2) Mathematically identical variables in different designs have contrasting ecological interpretations. For example, different sets of ecological processes can contribute to different variables in different experimental designs. (3) The frequency of transgressive overyielding of standing stock (e.g. total above ground biomass) in polycultures implies little about the prevalence of transgressive overyielding in other ecosystem processes. (4) Measuring the contribution to ecosystem functioning of individual species, rather than just total ecosystem functioning of a polyculture, is not essential for estimating effects of complementarity. (5) Further research will profit from distinguishing standing stock from all other ecosystem functions. (6) None of the analytic methods can distinguish the effects of individual processes or mechanisms such as resource use differentiation, facilitation, or allelopathy, for which additional experimental treatments are required.
Estimation by capture‐recapture of recruitment and dispersal over several sites
Authors: Lebreton J. D. , Hines J. E. , Pradel R. , Nichols J. D. , Spendelow J. A.
Published: December 2004

Dispersal in animal populations is intimately linked with accession to reproduction, i.e. recruitment, and population regulation. Dispersal processes are thus a key component of population dynamics to the same extent as reproduction or mortality processes. Despite the growing interest in spatial aspects of population dynamics, the methodology for estimating dispersal, in particular in relation with recruitment, is limited. In many animal populations, in particular vertebrates, the impossibility of following individuals over space and time in an exhaustive way leads to the need to frame the estimation of dispersal in the context of capture‐recapture methodology. We present here a class of age‐dependent multistate capture‐recapture models for the simultaneous estimation of natal dispersal, breeding dispersal, and age‐dependent recruitment. These models are suitable for populations in which individuals are marked at birth and then recaptured over several sites. Under simple constraints, they can be used in populations where non‐breeders are not observed, as is often the case with colonial waterbirds monitored on their breeding grounds. Biological questions can be addressed by comparing models differing in structure, according to the generalized linear model philosophy broadly used in capture‐recapture methodology. We illustrate the potential of this approach by an analysis of recruitment and dispersal in the roseate ternSterna dougallii.
Breeding success of sympatric dabbling ducks in relation to population density and food resources
Authors: Elmberg Johan , Nummi Petri , Pöysä Hannu , Sjöberg Kjell
Published: December 2004

Breeding success in sympatric mallard Anas platyrhynchos, teal A. crecca and wigeon A. penelope in a boreal watershed in Finland was studied for 12 years. Benthic and surface‐emerging prey animals were trapped to obtain annual indices of food abundance. Mallard and teal were equally abundant over the years, being roughly twice as numerous as wigeon.

Pair density, brood:pair ratio and duckling:pair ratio were used to test the hypothesis that per capita breeding success decreases in a density‐dependent fashion as either pair density or the number of nesting pairs per available food unit increases. In mallard we found no density‐dependent patterns at all. In teal per capita brood production decreased as prey animals became relatively scarcer, but this interpretation may not be robust. In wigeon, however, there were two independent significant patterns of direct density‐dependence in a temporal succession, i.e. between pair density and per capita brood production in the early part of the breeding season, and then between per capita abundance of surface‐emerging insect prey and the number of ducklings per pair. Despite wide dietary overlap and frequent co‐occurrence on single lakes among species in the guild, we found no evidence for interspecific density‐dependent effects. We hypothesize that there is no or infrequent food limitation for breeding dabblers in this system, and that behavior may be the process behind the pattern of density‐dependence in wigeon.
Functional responses in polar bear habitat selection
Authors: Mauritzen Mette , Belikov Stanislav E. , Boltunov Andrei N. , Derocher Andrew E. , Hansen Edmond , Ims Rolf A. , Wiig Øystein , Yoccoz Nigel
Published: December 2004

Habitat selection may occur in situations in which animals experience a trade‐off, e.g. between the use of habitats with abundant forage and the use of safer retreat habitats with little forage. Such trade‐offs may yield relative habitat use conditional on the relative availability of the different habitat types, as proportional use of foraging habitat may exceed proportional availability when foraging habitat is scarce, but be less than availability when foraging habitat is abundant. Hence, trade‐offs in habitat use may result in functional responses in habitat use (i.e. change in relative use with changing availability). We used logistic and log‐linear models to model functional responses in female polar bear habitat use based on satellite telemetry data from two contiguous populations; one near shore inhabiting sea ice within fjords, and one inhabiting pelagic drift ice. Open ice, near the ice edge, is a highly dynamic habitat hypothesised to be important polar bear habitat due to high prey availability. In open ice‐polar bears may experience a high energetic cost of movements and risk drifting away from the main ice field (i.e. trade off between feeding and energy saving or safety). If polar bears were constrained by ice dynamics we therefore predicted use of retreat habitats with greater ice coverage relative to habitats used for hunting. The polar bears demonstrated season and population specific functional responses in habitat use, likely reflecting seasonal and regional variation in use of retreat and foraging habitats. We suggest that in seasons with functional responses in habitat use, polar bear space use and population distribution may not be a mere reflection of prey availability but rather reflect the alternate allocation of time in hunting and retreat habitats.
Behavioural plasticity in relation to egg and time limitation: the case of two fly species in the genus Anastrepha (Diptera: Tephritidae)
Authors: Díaz‐Fleischer Francisco , Aluja Martín
Published: December 2004

Reproductive opportunities in insects that deposit their eggs in discrete resource patches are frequently limited because the availability of oviposition substrates is often spatially and temporally restricted. Such environmental variability leads individuals to confront time‐ or egg‐limitation constraints. Additionally, species with different oviposition strategies (i.e. single egg layers vs clutch layers) commonly deal with different structural and ecological characteristics of larval host plants. To test the hypothesis that oviposition strategies such as laying eggs singly or in batches (clutches) are related to these constraints (i.e. egg vs time limitation), we compared the lifetime oviposition patterns of two closely related sympatric species of Anastrepha (Diptera: Tephritidae) with different oviposition strategies. We exposed five cohorts of A. obliqua and A. ludens females, over the course of their adult lifetimes, to three conditions of “habitat quality” (measured as host density per cage): unpredictable habitat quality (host density varied randomly from day to day between 1, 5, 15, 30 and 60 hosts/cage), low habitat quality (fixed density of one host/cage) and high habitat quality (fixed density of 60 hosts/cage).

 Responses to host density conditions were strikingly different in the two species. (1) Frequency of host visits and oviposition events increased in A. obliqua but not in A. ludens when host densities increased. (2) Anastrepha ludens females accepted low quality hosts (i.e. fruits on which eggs had already been laid and were therefore partially covered with host marking pheromone) significantly more often than A. obliqua females did. (3) Females of A. obliqua adjusted their oviposition activity to variations in host density, whereas A. ludens females exhibited a constant oviposition pattern (i.e. did not respond to variations in host density). Based on the above, it is likely that in A. obliqua oviposition is governed by egg‐limitation and in A. ludens by time‐limitation constraints. We discuss the relationship between the oviposition strategies of each fly species and the fruiting phenology and density of their native host plants. We also address the possible influence of oogenesis modality and parasitism by braconid wasps in shaping oviposition behaviour in these insects.
A parasite spatially structures its host population
Authors: Wellnitz Todd , Giari Luisa , Maynard Barbara , Dezfuli Bahram S.
Published: December 2004

Acanthocephalan parasites are capable of altering the behavior of their intermediate amphipod hosts by inducing hyperactivity and increasing downstream drift. We used a laboratory and field study to investigate how Echinogammarus stammerii amphipods infected by the acanthocephalan Pomphorhychus laevis compensated for downstream displacement and responded to a fish extract predator cue. Experiments conducted in laboratory streams showed infected amphipods drifted more and compensated for drift less than non‐infected individuals. When fish extract was added to the channels, non‐infected individuals decreased their activity while infected individuals did not. A field study examined the up‐ and down‐stream movements of a population of E. stammerii infected with P. laevis in the River Brenta, Italy. Drift by E. stammerii was positively influenced by acanthocephalan infection. Infected amphipods made up 40% of the drift but accounted for just 5% of the E. stammerii population. Infected individuals, however, were under‐represented among upstream‐moving amphipods collected from the main river channel and a near‐shore migration column, comprising only 3% of sampled individuals. These data suggest that infected individuals may be effectively displaced downstream, creating a mechanism for spatial separation of the non‐infected and infected sub‐populations.