bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic variation in West Nile virus from naturally infected mosquitoes and birds suggests quasispecies structure and strong purifying selection
Authors: Jerzak Greta , Bernard Kristen A. , Kramer Laura D. , Ebel Gregory D.
Published: July 2005

Intrahost genetic diversity was analysed in naturally infected mosquitoes and birds to determine whetherWest Nile virus(WNV) exists in nature as a quasispecies and to quantify selective pressures within and between hosts. WNV was sampled from ten infected birds and ten infected mosquito pools collected on Long Island, NY, USA, during the peak of the 2003 WNV transmission season. A 1938 nt fragment comprising the 3′ 1159 nt of the WNV envelope (E) coding region and the 5′ 779 nt of the non-structural protein 1 (NS1) coding region was amplified and cloned and 20 clones per specimen were sequenced. Results from this analysis demonstrate that WNV infections are derived from a genetically diverse population of genomes in nature. The mean nucleotide diversity was 0·016 % within individual specimens and the mean percentage of clones that differed from the consensus sequence was 19·5 %. WNV sequences in mosquitoes were significantly more genetically diverse than WNV in birds. No host-dependent bias for particular types of mutations was observed and estimates of genetic diversity did not differ significantly between E and NS1 coding sequences. Non-consensus clones obtained from two avian specimens had highly similar genetic signatures, providing preliminary evidence that WNV genetic diversity may be maintained throughout the enzootic transmission cycle, rather than arising independently during each infection. Evidence of purifying selection was obtained from both intra- and interhost WNV populations. Combined, these data support the observation that WNV populations may be structured as a quasispecies and document strong purifying natural selection in WNV populations.
Interferon-induced exonuclease ISG20 exhibits an antiviral activity against human immunodeficiency virus type 1
Authors: Espert Lucile , Degols Geneviève , Lin Yea-Lih , Vincent Thierry , Benkirane Monsef , Mechti Nadir
Published: July 2005

Interferons (IFNs) encode a family of secreted proteins that provide the front-line defence against viral infections. It was recently shown that ISG20, a new 3′→5′ exoribonuclease member of the DEDD superfamily of exonucleases, represents a novel antiviral pathway in the mechanism of IFN action. In this report, it was shown that ISG20 expression is rapidly and strongly induced during human immunodeficiency virus type 1 (HIV-1) infection. In addition, it was demonstrated that the replication kinetics of an HIV-1-derived virus expressing the ISG20 protein (HIV-1NL4-3ISG20) was delayed in both CEM cells and peripheral blood mononuclear cells. No antiviral effect was observed in cells overexpressing a mutated ISG20 protein defective in exonuclease activity, suggesting that the antiviral effect was due to the exonuclease activity of ISG20. Paradoxically, despite the antiviral activity of ISG20 protein, virus rescue observed in HIV-1NL4-3ISG20-infected cells was not due to mutation or partial deletion of the ISG20 transgene, suggesting that the virus was able to counteract the cellular defences. In addition, HIV-1-induced apoptosis was significantly reduced in HIV-1NL4-3ISG20-infected cells suggesting that emergence of HIV-1NL4-3ISG20was associated with the inhibition of HIV-1-induced apoptosis. Altogether, these data reflect the ineffectiveness of virus replication in cells overexpressing ISG20 and demonstrate that ISG20 represents a new factor in the IFN-mediated antiviral barrier against HIV-1.
Biodiversity and ecosystem function in soil
Authors: FITTER A. H. , GILLIGAN C. A. , HOLLINGWORTH K. , KLECZKOWSKI A. , TWYMAN R. M. , PITCHFORD J. W. ,   THE MEMBERS OF THE NERC SOIL BIODIVERSITY PROGRAMME
Published: July 2005

Soils are one of the last great frontiers for biodiversity research and are home to an extraordinary range of microbial and animal groups. Biological activities in soils drive many of the key ecosystem processes that govern the global system, especially in the cycling of elements such as carbon, nitrogen and phosphorus.

We cannot currently make firm statements about the scale of biodiversity in soils, or about the roles played by soil organisms in the transformations of organic materials that underlie those cycles. The recent UK Soil Biodiversity Programme (SBP) has brought a unique concentration of researchers to bear on a single soil in Scotland, and has generated a large amount of data concerning biodiversity, carbon flux and resilience in the soil ecosystem.

One of the key discoveries of the SBP was the extreme diversity of small organisms: researchers in the programme identified over 100 species of bacteria, 350 protozoa, 140 nematodes and 24 distinct types of arbuscular mycorrhizal fungi. Statistical analysis of these results suggests a much greater ‘hidden diversity’. In contrast, there was no unusual richness in other organisms, such as higher fungi, mites, collembola and annelids.

Stable‐isotope (13C) technology was used to measure carbon fluxes and map the path of carbon through the food web. A novel finding was the rapidity with which carbon moves through the soil biota, revealing an extraordinarily dynamic soil ecosystem.

The combination of taxonomic diversity and rapid carbon flux makes the soil ecosystem highly resistant to perturbation through either changing soil structure or removing selected groups of organisms.
Effect of native and alien vertebrate frugivores on seed viability and germination patterns of Rubia fruticosa (Rubiaceae) in the eastern Canary Islands
Authors: NOGALES M. , NIEVES C. , ILLERA J. C. , PADILLA D. P. , TRAVESET A.
Published: July 2005

This study shows the first results obtained concerning the relative importance and effect on the seeds of a particular plant species, Rubia fruticosa Ait. (Rubiaceae), of passage through the digestive tube of the three main groups of vertebrate seed dispersers: native reptiles and birds, and alien mammals.

Native birds and reptiles dispersed a high proportion of undamaged seeds of R. fruticosa.

In contrast, seeds defecated by the two alien mammals showed significantly greater proportions of damaged seeds. Seed viability was much higher for reptiles and birds than for mammals, which was consistent with germination results.

Ingested seeds had a significantly thinner coat than uningested control seeds. Seeds that had passed through native dispersers had a significantly thicker coat than those passed through one of the alien mammals (the squirrel).

Considering both quantitative and qualitative components of seed dispersal, we conclude that native reptiles and birds are the most important seed dispersers in this multidisperser system.
Mantophasmatodea and phylogeny of the lower neopterous insects
Authors: Terry Matthew D. , Whiting Michael F.
Published: July 2005

Polyneoptera is a name sometimes applied to an assemblage of 11 insect orders comprising the lower neopterous or “orthopteroid” insects. These orders include familiar insects such as Orthoptera (grasshoppers), Blattodea (roaches), Isoptera (termites) (Mantodea) praying mantises, Dermaptera (earwigs), Phasmatodea (stick insects), Plecoptera (stoneflies), as well as the more obscure, Embiidina (web‐spinners), Zoraptera (angel insects) and Grylloblattodea (ice‐crawlers). Many of these insect orders exhibit a high degree of morphological specialization, a condition that has led to multiple phylogenetic hypotheses and little consensus among investigators. We present a phylogenetic analysis of the polyneopteran orders representing a broad range of their phylogenetic diversity and including the recently described Mantophasmatodea. These analyses are based on complete 18S rDNA, 28S rDNA, Histone 3 DNA sequences, and a previously published morphology matrix coded at the ordinal level. Extensive analyses utilizing different alignment methodologies and parameter values across a majority of possible ranges were employed to test for sensitivity of the results to ribosomal alignment and to explore patterns across the theoretical alignment landscape. Multiple methodologies support the paraphyly of Polyneoptera, the monophyly of Dictyoptera, Orthopteroidea (sensu Kukalova‐Peck; i.e. Orthoptera + Phasmatodea + Embiidina), and a group composed of Plecoptera + Dermaptera + Zoraptera. Sister taxon relationships between Embiidina + Phasmatodea in a group called “Eukinolabia”, and Dermaptera + Zoraptera (“Haplocercata”) are also supported by multiple analyses. This analysis also supports a sister taxon relationship between the newly described Mantophasmatodea, which are endemic to arid portions of southern Africa, and Grylloblattodea, a small order of cryophilic insects confined to the north‐western Americas and north‐eastern Asia, in a group termed “Xenonomia”. This placement, coupled with the morphological disparity of the two groups, validates the ordinal status of Mantophasmatodea.

© The Willi Hennig Society 2005.
Sodium hypochlorite oxidation reduces soil organic matter concentrations without affecting inorganic soil constituents
Authors: Siregar A. , Kleber M. , Mikutta R. , Jahn R.
Published: July 2005

Oxidative treatment can isolate a stable organic matter pool in soils for process studies of organic matter stabilization. Wet oxidation methods using hydrogen peroxide are widely used for that purpose, but are said to modify poorly crystalline soil constituents. We investigated the effect of a modified NaOCl oxidation (pH 8) on the mineral composition of 12 subsoils (4.9–38.2 g organic C kg−1) containing varying amounts of poorly crystalline mineral phases, i.e. 1.1–20.5 g oxalate‐extractable Fe kg−1, and of different phyllosilicate mineralogy. Post‐oxidative changes in mineral composition were estimated by (i) the determination of elements released into the NaOCl solution, (ii) the difference in dithionite‐ and oxalate‐extractable Si, Al and Fe, and (iii) the specific surface areas (SSAs) of the soils. The NaOCl procedure reduced the organic C concentrations by 12–72%. The amounts of elements released into the NaOCl extracts were small (≤ 0.14 g kg−1 for Si, ≤ 0.13 g kg−1 for Al, and ≤ 0.03 g kg−1 for Fe). The SSA data and the amounts of dithionite‐ and oxalate‐extractable elements suggest that the NaOCl oxidation at pH 8 does not attack pedogenic oxides and hydroxides and only slightly dissolves Al from the poorly crystalline minerals. Therefore, we recommend NaOCl oxidation at pH 8 for the purpose of isolating a stable organic matter pool in soils for process studies of organic matter stabilization.
Clay mineralogy determines the importance of biological versus abiotic processes for macroaggregate formation and stabilization
Authors: Denef K. , Six J.
Published: July 2005

Plant residues, living roots and microbial activity play an important role in aggregate formation and the stabilization of soil organic carbon (SOC), but their impact might differ among soils with different clay mineralogy. We investigated the effect of these organic agents on aggregation and SOC during a 76‐day incubation of 2‐mm sieved soil from an illitic Kastanozem and a kaolinitic Ferralsol, subjected to the following treatments: (i) control (no residue input or plant growth), (ii) residue input, (iii) living plants, and (iv) residue input and living plants. After 46 and 76 days, aggregate size distribution, aggregate‐associated SOC and microbial‐C were measured. In both soils, microbial‐C was less in the control than in the residue and/or plant treatments. After 46 days, new large macroaggregates (> 2000 µm) were formed in the control treatment of the kaolinitic soil, but not of the illitic soil. Control macroaggregates in the kaolinitic soil were formed out of silt and clay particles without accumulating C. Residue input and plant growth had a greater positive effect on macroaggregate formation in the illitic than in the kaolinitic soil. A stronger relation was found between microbial‐C and amount of large macroaggregates in the illitic than in the kaolinitic soil. We conclude that kaolinitic soils can rapidly form macroaggregates independent of biological processes due to physical or electrostatic interactions between the 1:1 clay minerals and oxides. However, biological processes led to stronger organic bonds between the illite compared with the kaolinite clay, resulting in more macroaggregates with long‐term stability in the illitic than in the kaolinitic soil.
Mechanisms controlling the mobility of dissolved organic matter, aluminium and iron in podzol B horizons
Authors: Jansen B. , Nierop K. G. J. , Verstraten J. M.
Published: July 2005

The processes governing the (im)mobilization of Al, Fe and dissolved organic matter (DOM) in podzols are still subject to debate. In this study we investigated the mechanisms of (im)mobilization of Al, Fe and organic matter in the upper and lower B horizons of two podzols from the Netherlands that are in different stages of development. We equilibrated batches of soil material from each horizon with DOM solutions obtained from the Oh horizon of the corresponding soil profiles. We determined the amount of (im)mobilized Al, Fe and DOM after addition of Al and Fe at pH 4.0 and 4.5 and initial dissolved organic carbon (DOC) concentrations of 10 mg C litre−1 or 30 mg C litre−1, respectively. At the combination of pH and DOC concentrations most realistic for the field situation, organic matter was retained in all horizons, the most being retained in the lower B horizon of the well‐developed soil and the least in the upper B horizon of the younger profile. Organic matter solubility seemed to be controlled mainly by precipitation as organo‐metal complexes and/or by adsorption on freshly precipitated solid Al‐ and Fe‐phases. In the lower B horizons, at pH 4.5, solubility of Al and Fe appeared to be controlled mainly by the equilibrium with secondary solid Al‐ and Fe‐phases. In the upper B horizons, the solubility of Al was controlled by adsorption processes, while Fe still precipitated as inorganic complexes as well as organic complexes in spite of the prevailing more acidic pH. Combined with a previous study of eluvial horizons from the same profiles, the results confirm the important role of organic matter in the transport of Al and Fe to create illuvial B horizons initially and subsequently deepening and differentiating them into Bh and Bs horizons.
Soil infiltration, runoff and sediment yield from a shallow soil with varied stone cover and intensity of rain
Authors: Mandal Uttam Kumar , Rao K. V. , Mishra P. K. , Vittal K. P. R. , Sharma K. L. , Narsimlu B. , Venkanna K.
Published: July 2005

Stones on the surface of the soil enhance infiltration and protect the soil against erosion. They are often removed in modern mechanized agriculture, with unfortunate side‐effects. We evaluated experimentally the influence of surface stones on infiltration, runoff and erosion under field conditions using a portable rainfall simulator on bare natural soil in semi‐arid tropical India, because modernization and mechanization often lead to removal of these stones in this region. Four fields with varied cover of stones from 3 to 65% were exposed to three rainfall intensities (48.5, 89.2 and 136.8 mm hour−1). Surface stones retarded surface runoff, increased final infiltration rates, and diminished sediment concentration and soil loss. The final infiltration ranged from 26 to 83% of rainfall when the rainfall intensity was 136.8 mm hour−1. The reduction in runoff and soil erosion and increase in infiltration were more pronounced where stones rested on the soil surface than where they were buried in the surface layer. The sediment yield increased from 2 g l−1 for 64.7% stone cover with rainfall of 48.5 mm hour−1 to 70 g l−1 for 3.5% stone cover with rain falling at 136.8 mm hour−1. The soil loss rate was less than 2 t ha−1 hour−1 for the field with stone cover of 64.7% even when the rainfall intensity was increased to 136.8 mm hour−1. The effects of stones on soil loss under the varied rainfall intensities were expressed mathematically. The particles in the sediment that ran off were mostly of silt size.
Neural network models to predict cation exchange capacity in arid regions of Iran
Authors: Amini M. , Abbaspour K. C. , Khademi H. , Fathianpour N. , Afyuni M. , Schulin R.
Published: July 2005

Design and analysis of land‐use management scenarios requires detailed soil data. When such data are needed on a large scale, pedotransfer functions (PTFs) could be used to estimate different soil properties. Because existing regression‐based PTFs for estimating cation exchange capacity (CEC) do not, in general, apply well to arid areas, this study was conducted (i) to evaluate the existing models and (ii) to develop neural network‐based PTFs for predicting CEC in Aridisols of Isfahan in central Iran. As most researches have found a significant correlation between CEC and soil organic matter content (OM) and clay content, we also used these two variables for modelling of CEC. We tested several published PTFs and developed two neural network algorithms using multilayer perceptron and general regression neural networks based on a set of 170 soil samples. The data set was divided into two subsets for calibration and testing of the models. In general, the neural network‐based models provided more reliable predictions than the regression‐based PTFs.
Stable isotopes, mesocosms and gut content analysis demonstrate trophic differences in two invasive decapod crustacea
Authors: RUDNICK DEBORAH , RESH VINCENT
Published: July 2005

1. Improving our understanding of dietary differences among omnivorous, benthic crustacea can help to define the scope of their trophic influence in benthic food webs. In this study, we examined the trophic ecology of two non‐native decapod crustaceans, the Chinese mitten crab (Eriocheir sinensis) (CMC) and the red swamp crayfish (Procambarus clarkii) (RSC), in the San Francisco Bay ecosystem to describe their food web impacts and explore whether these species are functionally equivalent in their impacts on aquatic benthic communities.

2. We used multiple methods to maximise resolution of the diet of these species, including N and C stable isotope analysis of field data, controlled feeding experiments to estimate isotopic fractionation, mesocosm experiments, and gut content analysis (GCA).

3. In experimental enclosures, both CMC and RSC caused significant declines in terrestrially derived plant detritus (P < 0.01) and algae (P < 0.02) relative to controls, and declines in densities of the caddisflyGumaga nigriculaby >50% relative to controls.

4. Plant material dominated gut contents of both species, but several sediment‐dwelling invertebrate taxa were also found. GCA and mesocosm results indicate that CMC feed predominantly on surface‐dwelling invertebrates, suggesting that trophic impacts of this species could include a shift in invertebrate community composition towards sediment‐dwelling taxa.

5. Stable isotope analysis supported a stronger relationship between CMC and both algae and algal‐associated invertebrates than with allochthonous plant materials, while RSC was more closely aligned with terrestrially derived detritus.

6. The trophic ecology and life histories of these two invasive species translate into important differences in potential impacts on aquatic food webs. Our results suggest that the CMC differs from the RSC in exerting new pressures on autochthonous food sources and shallow‐dwelling invertebrates. The crab's wide‐ranging foraging techniques, use of intertidal habitat, and migration out of freshwater at sexual maturity increases the distribution of the impacts of this important invasive species.
Additive partitioning of aquatic invertebrate species diversity across multiple spatial scales
Authors: STENDERA SONJA E. S. , JOHNSON RICHARD K.
Published: July 2005

1. Additive partitioning of three measures of diversity (species richness, Shannon's diversity index H and Simpson's diversity D) was used to study the relationship between local and regional diversity of benthic macroinvertebrate communities of boreal lakes (littoral habitats) and streams (riffle habitats) across three spatial scales (sampling sites, ecoregions and biogeographic regions).

2. Alpha (α) and beta (β) diversity are defined as within‐habitat and between‐habitat diversity, respectively. According to the concept of additive partitioning, diversity can be partitioned across multiple spatial scales such that the total (γ) diversity on one spatial scale becomes within‐habitat (α) diversity at the next higher scale. Hence, the total diversity at one scale is determined by the α diversity and the between‐habitat diversity (β) at the next lower scale. Consequently, one of the advantages of additive partitioning is that it is possible to study simultaneously β diversity and the regional‐local species relationship and the scale dependence of α and β components.

3. For both lakes and streams α diversity was low for sites and ecoregions, whereas β diversity was high, indicating that among‐site factors are important in describing the variability among the lakes and streams studied here.

4. Weak, albeit significant, evidence was found for regional and local species saturation patterns. Multiple stepwise regression indicated that local processes might be more important in structuring lake‐littoral and stream‐riffle species assemblages than regional processes. From these results we conclude that environmental heterogeneity may act as an important factor contributing to species coexistence, resulting in the observed saturation patterns.

5. Our study supports the use of additive partitioning for identifying specific patterns of macroinvertebrate diversity on multiple spatial scales and the underlying processes generating these patterns. This information is needed to improve understanding of the relation between patterns and processes affecting (decreasing) trends in aquatic biodiversity.
Water temperature determines strength of top‐down control in a stream food web
Authors: KISHI DAISUKE , MURAKAMI MASASHI , NAKANO SHIGERU , MAEKAWA KOJI
Published: July 2005

1. We examined effects of water temperature on the community structure of a three trophic level food chain (predatory fish, herbivorous caddisfly larvae and periphyton) in boreal streams. We used laboratory experiments to examine (i) the effects of water temperature on feeding activities of fish and caddisfly larvae and on periphyton productivity, to evaluate the thermal effects on each trophic level (species‐level experiment), and (ii) the effects of water temperature on predation pressure of fish on abundance of the lower trophic levels, to evaluate how temperature affects top‐down control by fish (community‐level experiment).

2. In the species‐level experiment, feeding activity of fish was high at 12 °C, which coincides with the mean summer temperature in forested streams of Hokkaido, Japan, but was depressed at 3 °C, which coincides with the mean winter temperature, and also above 18 °C, which coincides with the near maximum summer temperatures. Periphyton productivity increased over the range of water temperatures.

3. In the community‐level experiments, a top‐down effect of fish on the abundance of caddisfly larvae and periphyton was clear at 12 °C. This effect was not observed at 3 and 21 °C because of low predation pressure of fish at these temperatures.

4. These experiments revealed that trophic cascading effects may vary with temperature even in the presence of abundant predators. Physiological depression of predators because of thermal stress can alter top‐down control and lead to changes in community structure.

5. We suggest that thermal habitat alteration can change food web structure via combinations of direct and indirect trophic interactions.
The use of indicator taxa as representatives of communities in bioassessment
Authors: NIJBOER R. C. , VERDONSCHOT P. F. M. , VAN DER WERF D. C.
Published: July 2005

1. Sampling and processing of benthic macroinvertebrate samples is time consuming and expensive. Although a number of cost‐cutting options exist, a frequently asked question is how representative a subset of data is of the whole community, in particular in areas where habitat diversity is high (like Dutch surface water habitats).

2. Weighted averaging was used to reassign 650 samples to a typology of 40 community types, testing the representativeness of different subsets of data: (i) four different types of data (presence/absence, raw, 2log‐ and ln‐transformed abundance), (ii) three subsets of ‘indicator’ taxa (taxa with indicator weights 4–12, 7–12, and 10–12) and (iii) single taxonomic groups (n = 14) by determining the classification error.

3. 2log‐ and ln‐transformed abundances resulted in the lowest classification error, whilst the use of qualitative data resulted in a reduction of 10% of the samples assigned to their original community type compared to the use of ln‐transformed abundance data.

4. Samples from community types with a high number of unique indicator taxa had the lowest classification error, and classification error increased as similarity among community types increased. Using a subset of indicator taxa resulted in a maximum increase of the classification error of 15% when only taxa with an indicator weight 10–12 were included (error = 49.1%).

5. Use of single taxonomic groups resulted in high classification error, the lowest classification error was found using Trichoptera (68%), and was related to the frequency of the taxonomic group among samples and the indicator weights of the taxa.

6. Our findings that the use of qualitative data, subsets of indicator taxa or single taxonomic groups resulted in high classification error implies low taxonomic redundancy, and supports the use of all taxa in characterising a macroinvertebrate community, in particular in areas where habitat diversity is high.
Ecological interactions between Nile tilapia (Oreochromis niloticus, L.) and the phytoplanktonic community of the Furnas Reservoir (Brazil)
Authors: FIGUEREDO CLEBER C. , GIANI ALESSANDRA
Published: July 2005

1. Exotic invasive species modify natural food webs in a way frequently hard to predict. In several aquatic environments in Brazil the introduction of Oreochromis niloticus (tilapia) was followed by changes in water quality. Yet, because of its rapid and easy growth, this fish has been used in many aquaculture programmes around the country.

2. To measure the effects of tilapia on the phytoplankton community and on water conditions of a large tropical reservoir in south‐eastern Brazil (Furnas Reservoir), we performed two in situ experiments using three controls (no fish) and three tilapia enclosures (high fish density). Abiotic and biotic parameters were measured at 4 day intervals for 28 days.

3. Fish presence increased nitrogen (N) and phosphorus (P) availability (ammonium 260 and 70% mean increase – first and second experiment; and total phosphorus 540 and 270% mean increase) via excretion. Nutrient recycling by fish can thus be significant in the nutrient dynamics of the reservoir. The higher chlorophyll a concentration in the experimental fish tanks (86 and 34 μg L−1, first and second experiment, respectively) was the result of a positive bottom‐up effect on the phytoplankton community (approximately 2 μg L−1 in the reservoir and control tank).

4. Because tilapia feed selectively on large algae (mainly cyanobacteria and diatoms), several small‐sized or mucilaginous colonial chlorophyceans proliferated at the end of the experiments. Thus, the trophic cascade revealed strong influences on algal composition as well as on biomass.

5. Tilapia can contribute to the eutrophication of a waterbody by both top‐down and bottom‐up forces. In particular, by supplying considerable amount of nutrients it promotes the increase of fast growing algae. Tilapia must be used cautiously in aquaculture to avoid unexpected environmental degradation.
Strong impact of wintering waterbirds on zebra mussel (Dreissena polymorpha) populations at Lake Constance, Germany
Authors: WERNER STEFAN , MÖRTL MARTIN , BAUER HANS‐GÜNTHER , ROTHHAUPT KARL‐OTTO
Published: July 2005

1. Since zebra mussel invaded Lake Constance in the 1960s the number of wintering waterbirds increased fourfold. We studied the impact of predation by waterbirds (tufted duckAythya fuligula, pochardAythya ferinaand cootFulica atra) on the population ofDreissena polymorphain winter 2001/2002. These three species, with monthly peak numbers of approximately 230 000 individuals, currently comprise up to 80% of the waterbird population wintering at Lake Constance.

2. Four different study sites and four depths, that represent typical and characteristic habitats of mussels in Upper Lake Constance, were chosen.

3. Zebra mussels were sampled before, during and after predation by waterbirds. Their biomass in shallow areas decreased by >90%; the biomass reduction in deeper areas was highly variable and dependent on the substratum. With one exception, no changes could be detected at the greatest depth (11 m).

4. Concurrent exclosure studies revealed that the decrease in zebra mussels was caused by waterbird predation. A GIS‐based approximation revealed that in an area of 1 km2a total of approximately 750 t mussel fresh mass was removed by birds, which is equivalent to 1390 g mussels per bird per day.

5. Wintering waterbirds have a strong structural impact on the littoral community of Lake Constance and could be the key predator of zebra mussels.
Nitrogen absorption by roots as a cause of interspecific variations in leaf nitrogen concentration and photosynthetic capacity
Authors: OSONE Y. , TATENO M.
Published: July 2005

Optimal biomass allocation models predicted that an increase in specific absorption rate (SAR: nitrogen absorption rate per unit root dry weight) increases the optimal leaf N concentration (LNC) which maximizes whole‐plant growth rates. From this prediction, we hypothesized that inherent differences in the N absorption ability of roots, which is represented by differences in SAR, causes interspecific differences in LNC and photosynthetic capacity (Pmax).

Four deciduous tree species and three herb species were grown under controlled conditions to test this hypothesis. Despite growing under the same soil N conditions, the SAR of these species differed more than sixfold, with the deciduous trees having a smaller SAR than the herbs. Consistent with the hypothesis, there were strong positive correlations between SAR, LNC and Pmax. Leaf dry mass per area and the LNC–Pmax relationship, factors correlated with leaf life span, differed little among the species, suggesting a small effect of differences in these properties on the variation in LNC.

Simulations were performed using an optimal biomass allocation model and parameter values determined from measurements of each species. These demonstrated that the observed variation in LNC could be explained largely by differences in the N absorption ability of the species.

Additionally, the causal relationship between N absorption ability and LNC, suggested by optimal biomass allocation models, was verified by manipulating the biomass allocation between roots and leaves of Morus bombycis using uniconazole, an inhibitor of gibberellin synthesis.

These results indicate a close functional link between N absorption ability and LNC, which would account for large variations in LNC and Pmax across species.
CO2and nitrogen, but not population density, alter the size and C/N ratio ofPhytolacca americanaseeds
Authors: HE J.‐S. , FLYNN D. F. B. , WOLFE‐BELLIN K. , FANG J. , BAZZAZ F. A.
Published: July 2005

Plants can provision seeds by optimizing seed size, number and nutrient content to maximize parental fitness. According to the McGinley–Charnov hypothesis, seed size should be determined by the ratio of carbon to nitrogen (C/N) available to the plant, with larger seed size correlating with larger C/N ratios and smaller absolute N content.

This hypothesis was tested by establishing monocultures ofPhytolacca americanaL. (Phytolaccaceae) at three population densities under ambient and elevated CO2environments, with two availabilities of soil N.

Elevated CO2reduced both seed size and N concentration while increasing the C/N ratio; high soil N availability produced the opposite result for N concentration and C/N ratio. Higher planting densities reduced plant biomass, but did not alter seed size.

In accordance with the McGinley–Charnov hypothesis, larger seeds had both larger C/N ratios and smaller N content. However, the increase in C/N ratio caused by elevated CO2corresponded with smaller seeds overall: elevated CO2reduced seed size, although the seed size–C/N relationship remained positive.

These results suggest an alternative mechanism to explain variation in seed size, and suggest that future climate conditions may alter seed quality and plant reproductive behaviour.
Tree growth is related to light interception and wood density in two mixed dipterocarp forests of Malaysia
Authors: KING D. A. , DAVIES S. J. , SUPARDI M. N. NUR , TAN S.
Published: July 2005

The development of simple predictors of tree growth is important in understanding forest dynamics. For this purpose, tree height, crown width in two perpendicular directions, trunk diameter at 1·3 m height (d.b.h.) and crown illumination index (CI) were determined for 727 pole‐sized trees (8–20 cm d.b.h.) of 21 species, on forest dynamics plots at Pasoh Forest Reserve, Peninsular Malaysia and Lambir Hills National Park, Sarawak, Malaysia. A light‐interception index (LI = AcrCI2, where Acr is crown area) was calculated for each tree, and wood density (stem wood dry mass/fresh volume) was estimated for each species from reported values.

Diameter growth rates were linearly correlated with LI (mean per species r2 = 0·45, excluding substantially damaged and vine‐covered trees).

Among trees of all species, diameter growth rate was highly correlated with LI/wood density.

Mean growth rate per species varied 10‐fold among the study species, but increased linearly with mean LI/wood density ratio (r2 = 0·78), consistent with the previous pattern.

Thus much of the variability in tree growth rates, both within and among species, can be accounted for by the simple mechanistic assumption that, within a given size class, growth is proportional to light interception/wood density.
Genotype by environment interactions in the nectar production of Echium vulgare
Authors: LEISS K. A. , KLINKHAMER P. G. L.
Published: July 2005

Genotype by environment interactions for nectar production in Echium vulgare were studied. Nectar production was measured under high and low‐water treatments for high and low nectar‐producing genetic lines in a growth chamber. In the field the response of nectar production and pollinator behaviour to water availability for potted plants chosen from field populations was studied.

Plants selected from high‐nectar lines produced significantly more nectar than those selected from low‐nectar lines. Nectar production thus had a heritable component.

Under high water conditions plants produced more nectar than under low water conditions. The increase in nectar production under high water availability was strongest for the low‐nectar plants, demonstrating a genotype by environment interaction. Only under dry conditions, which usually prevail during the flowering period of E. vulgare, high and low‐nectar plants differ in nectar production.

Plants selected from high‐nectar lines had a significantly higher root mass and root : shoot ratio. This suggests that they are less affected by low water availability and thus able to maintain high nectar production under dry conditions.

In the field, high‐nectar plants produced significantly more nectar but did not receive more pollinator visits. Watered plants produced significantly more nectar and did receive an enhanced pollinator service. When watered, nectar production and pollinator service was similar for high and low‐nectar plants.
Foliar fibre predicts diet selection by invasive Red Deer Cervus elaphus scoticus in a temperate New Zealand forest
Authors: FORSYTH D. M. , RICHARDSON S. J. , MENCHENTON K.
Published: July 2005

There is much interest in how herbivores interact with plant communities, but the association between foliar traits and the feeding behaviour of invading browsing mammals has not been explored in this context.

We investigated whether eight foliar traits predicted the preferences of invasive Red Deer for 21 woody plant species in lowland forest in southern New Zealand.

The four models with substantial support for predicting variation in two indices of diet selection all included one or more traits related to foliar fibre (acid detergent fibre; acid detergent cellulose; acid detergent lignin). In all models the coefficients were negative, indicating that as the concentrations of foliar fibre increased, the preference of deer for foliage decreased.

Our results thus link the feeding behaviour of Red Deer with previously demonstrated shifts in the composition of New Zealand forests towards understorey species and leaf litter with high concentrations of foliar fibre.
Effects of season, understorey vegetation density, habitat edge and tree diameter on patch‐use by bark‐foraging birds
Authors: WHELAN C. J. , MAINA G. G.
Published: July 2005

We provided equal feeding opportunities for bark‐foraging bird species across seasons, cleared and uncleared woody understories, edge‐to‐interior habitat and tree diameters in a deciduous oak forest in north‐eastern Illinois, USA, to determine habitat preferences of these bird species. We determined habitat preferences by quantifying patch‐use intensity.

Patch‐use intensity was greater in the breeding season than in the non‐breeding season, and in interior than in edge habitat. In addition, however, we found interactions among the habitat variables. For instance, these bird species showed significant preferences for foraging in woodland interior habitat and on large diameter trees in the breeding season, but not in the non‐breeding season.

Foraging preferences were further affected by understorey clearing, with preference for interior over edge habitat reversed in the cleared habitat in the non‐breeding season. This effect may reflect unintended consequences of topography, an uncontrolled factor outside the experiment protocol.

Overall, the results suggest that patch‐use results from the response of the bird species to effects of vegetation variation from edge to interior habitat on both microclimate and predation risk. Those effects of vegetation may disappear or diminish when understorey vegetation is removed or reduced.
Super size me: an experimental test of the factors affecting lipid content and the ability of residual body mass to predict lipid stores in nestling European Starlings
Authors: ARDIA D. R.
Published: July 2005

Lipids are a major source of energy storage in vertebrates. A cross‐fostering brood manipulation was conducted to assess the role of rearing environmentvscommon origin on lipid stores.

Rearing conditions, especially nest temperatures, explained more variation in lipid levels than did nest of origin. As nest temperatures increased, lipid levels in nestlings also increased. Larger individuals, reflected in both wet and lean dry mass, tended to store more lipids.

There was no trade‐off between structural growth and lipid stores. However, body mass growth was linked with lipids. In addition, nestlings raised early in the season tended to maintain greater lipid levels, suggesting a role of individual quality.

Because the assessment of lipid stores is difficult, it is common to use residual body mass (RBM) as a surrogate. Multiple methods of calculating RBM were compared with actual lipid mass in nestling European Starlings (Sturnus vulgaris). RBM was correlated with lipid levels (R2up to 0·66); models calculated using ordinary least squares regression predicted lipid stores better than reduced major axis regression.

These results indicate that RBM can be a non‐invasive predictor of lipid levels in nestling birds and that studies examining variation in physiological stores should consider development conditions and individual quality.
Digestive plasticity in Mallard ducks modulates dispersal probabilities of aquatic plants and crustaceans
Authors: CHARALAMBIDOU I. , SANTAMARÍA L. , JANSEN C. , NOLET B. A.
Published: July 2005

The consequences of plastic responses of the avian digestive tract for the potential of birds to disperse other organisms remain largely uninvestigated.

To explore how a seasonal diet switch in Mallard (Anas platyrhynchos L.) influences their potential to disperse plants and invertebrates, we recorded the retention time of markers, following exposure to two diets of contrasting digestibility (trout chow vs seeds).

We then recorded the retrieval and germination of Fennel Pondweed (Potamogeton pectinatus L.) seeds and Brine Shrimp (Artemia franciscana Kellogg) cysts ingested by the same birds.

Gut passage rates of markers were increasingly longer in birds on the seed‐based, high‐fibre diet and shorter in birds on the animal‐based, low‐fibre one.

Propagule digestibility, and thus survival to gut passage, differed between diet groups, with more seeds and fewer cysts retrieved from ducks on the animal‐based diet. Germination decreased with retention time, but was not affected by diet.

Differences in passage rates of markers but not of seeds and cysts suggest no change in dispersal distances of plants and invertebrates between seasons, while differences in digestibility would affect the numbers of propagules dispersed.
The role of distillation on the quality of tequila
Authors: Rogelio Prado‐Ramírez , Victor Gonzáles‐Alvarez , Carlos Pelayo‐Ortiz , Norberto Casillas , Mirna Estarrón , Héctor E. Gómez‐Hernández
Published: July 2005

The role of a batch rectification on the quality of tequila, a traditional Mexican beverage, was studied. It was shown that the official tequila standard composition, particularly the size of the slop cuts and the correct balance of flavour constituents, can be determined by monitoring the concentration of the regulated compounds (ethanol, methanol, higher alcohols, ethyl acetate, acetaldehyde and furfural) throughout the rectification process. It was found that these regulated compounds are produced over the same time scales when either stainless steel or copper alembics are used. When distillations were done in copper alembics, however, it was found that the copper content of the rectified product exceeded the amount permitted in the official tequila standards. Finally, we report a comparison of sensory properties of tequila distillates obtained in both copper and stainless steel alembics.
Antioxidant Effect of Korean Traditional Lotus Liquor (Yunyupju)
Authors: Lee Hyo Ku , Choi Yang Mun , Noh Dong Ouk , Suh Hyung Joo
Published: July 2005

This study presented the antioxidant activities of the Korean traditional lotus liquor (Yunyupju) made from lotus blossom and leaves. The antioxidant activities are dose‐dependent and reached a plateau (about 80% inhibition) when the concentration of lotus liquor exceeded 25 μg in a modified linoleic acid peroxidation induced by haemoglobin. The concentrations to attain one absorbance unit at 700 nm were 23.6 ± 1.2 μg for Butylated hydroxytolene (BHT), and 45.7 ± 5.4 μg for lotus liquor. The scavenging activities of DPPH exerted by lotus liquor as well as α‐tocopherol were tested. Linear response curves were also obtained and the IC50 were estimated as 5.6 μg for α‐tocopherol, 17.9 μg for lotus liquor. The maximum scavenging activity on hydroxyl radicals (40%) could be achieved when lotus liquor was more than 500 μg. Lotus liquor also has a potent superoxide radical scavenging activity, with value of 0.93 unit mg−1 as superoxide dismutase equivalents. The IC50 was estimated as 1.07 ± 0.04 mg for lotus liquor. The high performance liquid chromatography analysis of polyphenols was successfully achieved as these compounds appeared at 16.30 (catechin), 21.87 (rutin), 25.88 (unidentified peak), 31.51 (quercitrin), 35.19 (myricetin), and 36.72 (quercetin) min after injection of the sample, respectively.
Activities of antioxidant enzymes in rats fed with hot‐smoked rainbow trout (Oncorhynchus mykiss)
Authors: Ünlüsayın Mustafa , Kaleli Süleyman , Bilgin Şengül , İzci Levent , Günlü Ali
Published: July 2005

The activities of antioxidant enzymes in rats fed with hot‐smoked rainbow trout (Oncorhynchus mykiss) was investigated. Four diets containing fresh and hot‐smoked rainbow trout flesh and vitamin were prepared and commercial pellet food purchased. Four groups of rats were fed with the diets for 28 days. Body weight was checked weekly. No significant (P > 0.05) differences were found in weight between groups. Malondialdehyde (MDA) values of group B and group D were found to be significantly increased (P < 0.05). Differences in glutathione peroxidase (GPX) and glutathione reductase (GR) values were not significant (P > 0.05) between groups. The difference in superoxide dismutase (SOD) and catalase (CAT) values was found to be significant (P < 0.05). The hot smoked process led to significant changes as decreased in the antioxidant enzymes activities. Our results indicate that determination of MDA, GPX, GR, SOD and CAT parameters in blood may help to point out cancer risk in humans.
Textural modification of soya bean/corn extrudates as affected by moisture content, screw speed and soya bean concentration
Authors: Li Si‐quan , Zhang Howard Q. , Tony Jin Z. , Hsieh Fu‐hung
Published: July 2005

A Clextral BP‐10 (type BC45) co‐rotating twin‐screw extruder was used for texture modification of extrudates. Dry materials were mixed in a mixer for 15 min at low speed before extrusion. Moisture content 21–23% and addition of soya bean flour (0–40%) showed significant influences on the texture of the extrudates. Addition of soya bean flour in the range from 0 to 40% increased the diametrical expansion ratio (P < 0.01), decreased the hardness (P < 0.01) and modifies specific volume and chewing behaviours of the extrudates. Increasing moisture content in the range from 21 to 23%, however, significantly decreased specific volume (P < 0.01), and increases hardness (P < 0.01) of the extrudates. The hardness and crispness of the extrudates at fracturability of 110 g were graded higher than 6.0 by 30 and 27 of 34 consumer panelists, respectively. Consumer purchase intent showed the highest score of 5.5 in a 9‐point hedonic scale when sample fracturability was at 110 g.
An apparatus for on‐line measuring electric field intensity during microwave heating: a theoretical consideration
Authors: Fu Yi‐Chung , Yang Binghuei B. , Chen Chung‐Jen , Sheen Shiow‐Shuh
Published: July 2005

A simple minimally perturbing method and an apparatus for on‐line measuring the electric field (E‐field) intensity at a particular small region, or a localized point in an electromagnetic field is described. The theoretical considerations and methodology for on‐line measuring electric field intensity are presented. They are based on measurement of the differential heating of the temperature rise using a fiberoptic temperature sensor at which a selected droplet of dielectric medium is dissipated in an electromagnetic field. The performance of the apparatus was examined and verified from power dissipation calculations of the water load. There was good agreement between the experimental and predicted value of average water temperature based on electric field on‐line measurement.