bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Added Substrate on Production of Red Swamp Crawfish, Procambarus clarkii, in Earthen Ponds without Planted Forage
Authors: D’Abramo Louis R. , Ohs Cortney L. , Elgarico Kathleen C. E.
Published: August 2006

The effects of addition of substrate consisting of plastic mesh fencing to experimental earthen ponds were evaluated for the culture of the red swamp crawfish, Procambarus clarkii, without planted forage. Mean daily yield (kg/ha/d), number of crawfish harvested (number/ha/d), and mean individual harvest weight were compared for ponds with and without substrate during a 2‐yr period. The surface area of added substrate was equivalent to 50% of the bottom surface area of the pond. Mean daily yield in the ponds containing substrate, based on a comparison with that of the previous year, increased by 80.2% and was principally attributed to a 66.7% increase in the number of crawfish harvested. Comparative values for the ponds without substrate were −13.1 and −11.7%. For the second year, the treatment‐dependent response was consistent. Mean daily yield for the substrate ponds increased by 48.8% compared to 15.0% for the ponds lacking substrate. The primary benefit of the substrate appears to be provision of refuge and three‐dimensional distribution of crawfish in the pond, thereby reducing the incidence of cannibalism and increasing the total number of crawfish harvested per hectare per day. The benefit of the substrate in a commercial production setting must be weighed against its cost and longevity as well as the conditions of the particular management scenario into which it may be incorporated.
Solar Chimney Power Plant Performance
Authors: Pretorius Johannes P. , Kröger Detlev G.
Published: August 2006

This paper evaluates the performance of a large-scale solar chimney power plant. The study considers the performance of a particular reference plant under specified meteorological conditions at a reference location in South Africa. A computer simulation program is employed to solve the governing conservation and draught equations simultaneously. Newly developed convective heat transfer and momentum equations are included in the numerical model and multiple simulations are performed. Results indicate 24hr plant power production, while illustrating considerable daily and seasonal power output variations. It is shown that plant power production is a function of the collector roof shape and inlet height.
Development of Heat-Storage System Using Metal Hydraid: Experiment of Performance by the Actual Loading Condition
Authors: Koseki Takami , Takeda Harunobu , Iijima Kazuaki , Murai Masamitu , Matsufuji Hisayoshi , Kawaguchi Osamu
Published: August 2006

The application of an innovative heat-storage system with metal hydride to building air-conditioning is investigated. Metal hydrides characteristically generate heat through the absorption process and absorb heat through the desorption process, allowing the development of a new air-conditioning system without chlorofluorocarbons. The trial system is composed of two heat-storage vessels, a “shell-and-tube-type” heat exchanger built with heat transfer fins and filled with metal hydride, and a compressor equipped for hydrogen transfer. The purpose of heat storage is to decrease the difference between electric power demand in the daytime and at night. This system transfers hydrogen using electric power at night and reverses the reaction during the day using only the pressure difference between two heat-storage vessels. The experimental results indicate that heat-storage is attained within a limited time, and the heat-storage quantity is 13.5MJ, which is sufficient for the heat capacity to cool the 10m2 room for 3hr. The stored heat per unit metal hydride volume is 289MJ∕m3, which is sufficiently higher than the conventional system using water or ice. In addition, the coefficient of performance of the system is 2.44.
Pyrometric Temperature Measurements on Solar Thermal High Temperature Receivers
Authors: Pfänder Markus , Lüpfert Eckhard , Heller Peter
Published: August 2006

The knowledge of the absorber surface temperature distribution is essential for efficient operation and further development of solar thermal high temperature receivers. However, the concentrated solar radiation makes it difficult to determine the temperature on irradiated surfaces. Contact thermometry is not appropriate and pyrometric measurements are distorted by the reflected solar radiation. The measurement in solar-blind spectral ranges offers a possible solution by eliminating the reflected solar radiation from the measurement signal. The paper shows that besides the incoming solar radiation and the absorber emittance, the bi-directional reflection properties and the temperature of the object are determining for the required selectivity of the spectral filter. Atmospheric absorption affects the solar blind pyrometric measurements in absorption bands of CO2 and water vapor. The deviation of temperature measurement due to atmospheric absorption is quantified and the possibilities and limitations of accounting for the atmospheric absorption with models based on radiation transfer calculations are discussed.
Effect of Unglazed Transpired Collector on the Performance of a Polycrystalline Silicon Photovoltaic Module
Authors: Naveed A. T. , Kang E. C. , Lee E. J.
Published: August 2006

The electrical power generated by a polycrystalline silicon photovoltaic (PV) module mounted on an unglazed transpired solar collector (UTC) has been studied and compared to that of a PV module without UTC for a quantitative analysis of electrical output and its role in reducing the simple payback periods of photovoltaic electrical systems. A 75W polycrystalline silicon PV module was fixed on an UTC in front of the ventilation fan, and effectiveness of cooling by means of the forced ventilation at the rate of 160CFM was monitored. The temperature reduction under forced ventilation was in the range of 3-9°C with a 5% recovery in the electrical output power on a typical day of the month of February 2005. The simulated and measured electrical power outputs are in reasonable agreement with root-mean-square error of 2.40. The life cycle assessment of a hypothetical PV system located at Daejeon, South Korea and consisting of 3kW PV modules fixed on a 50m2 UTC shows that with a possible reduction of 3-9°C in the operating temperatures, the system requires three 75W fewer PV modules. The simple payback period of PV system is reduced from 23yearsto15years when integrated into an UTC air heating system.
Morphological and anatomical development in the Vitaceae. VIII. Comparative development of three Cyphostemma (Vitaceae) species reveals important vegetative and reproductive differences among the species
Authors: Wilson Trevor C. , Gerrath Jean M. , Posluszny Usher
Published: August 2006

Vegetative and floral development of Cyphostemma simulans (C.A. Small) Wild & Drummond, Cyphostemma juttae (Dinter & Gilg) Descoings, and Cyphostemma mappia (Lam) Galet were compared using epi-illumination light microscopy and paraffin sectioning. Cyphostemma simulans is a liana with leaf-opposed tendrils and inflorescences, which both arise from the shoot apical meristem, whereas the other two species are shrubs that lack tendrils and their main shoot terminates in an inflorescence. A shoot apical meristem of C. simulans can be overtopped by an inflorescence, making the architecture appear to develop like a sympodium, which is the architecture shared by the other two species. On the other hand, a terminal inflorescence of C. juttae or C. mappia can be placed in a leaf-opposed position by a precocious axillary branch, making the architecture appear to develop like a monopodium, which is the typical architecture of the Vitaceae. The floral development of all three species is similar in early ontogeny, except for a difference in calyx development between C. mappia and the other two species. Later developmental differences of the septum and gynoecium, in addition to flower colour and phenology, are distinct characteristics that distinguish flowers of each species. Therefore, this study is the first to demonstrate differences in the floral characteristics of Cyphostemma. In addition, it shows how each architecture type (monopodium or sympodium) can resemble the other and so provides stronger evidence about how the unique architecture of the Vitaceae has originated.
Biodiversity of foliar fungal endophytes in white spruce (Picea glauca) from southern Québec
Authors: Stefani F.O.P. , Bérubé J.A.
Published: August 2006

The objective of this study was to investigate the foliar endophyte biodiversity of white spruce ( Picea glauca (Moench) Voss to establish a baseline for future comparative studies examining the impact of forestry practices. It identifies for the first time endophytic fungi living inside the needles of white spruce from 280 needles collected in seven natural stands in southern Québec. The endophyte colonization rate on surface sterilized needles was 53.2%. We performed a PCR-RFLP and sequence analysis on the ITS region of the nuclear ribosomal DNA to achieve molecular identification. Isolate ITS sequences were compared with data from GenBank presenting the best similarity and were analyzed by a maximum of parsimony and Bayesian inference. Relationships between morphological groups, digestion groups, and sequence groups were investigated. In all, 23 morphotypes were found to belong to 14 sequence groups and we demonstrated that morphological groups are poor indicators for estimating species diversity. This study is the first to establish species richness values for foliar endophytes. Among the 141 isolates in this study, 75.15% have a high sequence similarity with Lophodermium piceae , 10.95% with an unknown species of Mycosphaerella , and 5.5% with two species of the genus Hypoxylon . Distribution, incidence and biological significance of all the endophytes found in this study are discussed.
Differential effects of nitrate and ammonium supply on nodule initiation, development, and distribution on roots of pea (Pisum sativum)
Authors: Bollman Mavis I. , Vessey J. Kevin
Published: August 2006

Low, static concentrations of ammonium have less negative effects on nodulation of pea ( Pisum sativum L.) than nitrate and in some cases may actually stimulate nodulation. Two experiments were carried out to assess the effects of supplying both forms of mineral N, separately and in combination, on nodule initiation, nodule development, nodule distribution between primary and lateral (secondary) roots, tertiary root development, and N2 fixation in pea. Pea plants were grown for up to 24 d after inoculation in hydroponic culture with no mineral N (zero N), NO3– (0.5 mmol·L–1), NH4+ (0.5 mmol·L–1), or NO3– (0.25 mmol·L–1) plus NH4+ (0.25 mmol·L–1). Concentrations of nitrate and ammonium were monitored on a daily basis and held relatively constant by continuous, automatic additions of stock solutions. Pea plants accumulated the most total dry mass (DM) and total N when supplied with the combination of nitrate plus ammonium but had the lowest nodule DM and percentage of nitrogen derived from the atmosphere. Whole-plant nodulation (nodules per plant) and DM-specific nodulation (nodules·g–1 root DM) were 2.3- and 2.4-fold greater, respectively, in pea plants receiving NH4+ at 0.5 mmol·L–1 than in those supplied with NO3– at 0.5 mmol·L–1. The nodulation responses of plants receiving NO3– at 0.25 mmol·L–1 plus NH4+ at 0.25 mmol·L–1 were more similar to those of plants receiving only nitrate than only ammonium, indicating that when both forms of mineral N are available to plants, nitrate has a predominant effect on the nodulation response. Assessment of the stage of development of nodule primordia and nodules during the time course of the experiments indicated that nitrate not only decreased the degree of nodule initiation but also the rate at which those nodules developed. Microscopic observations indicated that the more negative effects of the nitrate treatment on DM-specific nodulation as compared with the ammonium treatment were consistent on both the primary and lateral roots. Quantification of nodulation and tertiary root development on lateral roots indicated that the stimulating effects of ammonium were specific to nodulation; the effects on tertiary root development were different. The study demonstrates for the first time that when both forms of mineral N are available at equal concentrations, the nodulation response in pea is influenced more by nitrate than by ammonium and that the effects of nitrate and ammonium on tertiary root initiation and development are unlike those on nodulation.
PpAG1, a homolog ofAGAMOUS, expressed in developing peach flowers and fruit
Authors: Martin Teresa , Hu Ming , Labbé Hélène , McHugh Sylvia , Svircev Antonet , Miki Brian
Published: August 2006

MADS-box transcription factors are known to play a central role in floral organ identity and floral meristem determinacy in many gymnosperms and angiosperms. Studies of this nature are limited in fruit tree species despite the economic importance of this group. A peach ( Prunus persica (L.) Batsch) gene, PpAG1, was isolated and shown to be homologous to the Arabidopsis thaliana (L.) Heynh. MADS-box gene AGAMOUS (AG). It is a single gene in peach and codes for a type II or MIKC-type MADS-box protein. The features of the deduced protein sequence indicate that it is similar to other AG homologs from woody plant species. The spatial and developmental patterns of expression parallel those of AG and homologs from other angiosperms with similar floral structures but with some minor differences. In the floral meristem, where AG is responsible for conversion of the vegetative meristem into the floral meristem, the differentiation of the whorls that generate the carpels and stamens coincides with the tissue-specific expression of PpAG1. It continues to be expressed in the ovules, developing fruit and seeds that subsequently develop from the carpels. Constitutive overexpression of PpAG1 in Arabidopsis, using the 35S promoter, caused the homeotic conversion of sepals to carpelloid tissues and altered petal development. This is consistent with C-function genes according to the ABC model of flower development. The data support the conclusion that PpAG1 is the peach homolog of Arabidopsis AG.
Seed production inCardiocrium cordatum: effects of nitrogen and dry mass availability of a plant
Authors: Sakai Satoki , Sakai Akiko , Fujioka Kohta
Published: August 2006

To clarify how seed production depends on the relative N and dry mass availability, we examined the number and size of seeds, and the loss of dry mass in Cardiocrium cordatum (Thunb.) Makaino plants that differed naturally in overall size and stem N content. After adjusting for plant size (basal stem diameter was used as a criterion of plant size), the amount of dry mass lost because of respiration in a plant decreased with an increase in the stem N content of the plant, whereas the total dry mass of seeds of a plant increased with an increase in the stem N content. Plants with a high stem N content relative to dry mass status used dry mass resources more efficiently in seed production by reducing the loss of dry mass. Plants with a higher stem N content produced a greater number of seeds, and the amount of dry mass lost decreased with an increase in the number of seeds of the plant, possibly because the resources allocated to seed production are consumed rapidly, if numerous seeds simultaneously absorb those resources. However, the stem N content of a plant had no influence on the mean seed dry mass, seed N content, and the seed N concentration, and the latter three parameters did not affect respiration loss of dry mass. We concluded that plants undergoing seed production reduce dry mass loss if their relative N to dry mass availability is high, through an increase in the numbers of seeds they produce.
Response of red-osier dogwood (Cornus sericea) seedlings to NaCl during the onset of bud break
Authors: Mustard Jennifer , Renault Sylvie
Published: August 2006

A greenhouse study was designed to test the response of red-osier dogwood (Cornus sericea L.) to NaCl during the onset of bud break. Seedlings treated with 50 mmol·L–1NaCl for 32 d had lower shoot dry mass and shoot height than untreated seedlings. Transpiration and photosynthetic rates, chlorophyll b and carotenoid concentrations of red-osier dogwood seedlings were significantly reduced by NaCl treatment. The shoots of seedlings treated with 50 mmol·L–1NaCl had a higher bulk modulus of cell wall elasticity than those of untreated seedlings, but the water potential components determined from the pressure-volume curves, osmotic potential and pressure potential at full turgor and osmotic potential at pressure loss, suggest that this change did not contribute to salt tolerance. Minor changes, including a small increase in arabinose of the hemicellulose fraction and a decrease in both galactose and rhamnose of the pectin fraction, also occurred in response to NaCl treatment. These changes in cell wall composition and elasticity could be partly attributed to differences in the developmental stage of the shoot tissues resulting from the delay in bud breaking in salt treated plants.
Integrated long-term responses of an arctic–alpine willow and associated ectomycorrhizal fungi to an altered environment
Authors: Clemmensen Karina E. , Michelsen Anders
Published: August 2006

We evaluated ectomycorrhizal (ECM) colonization and morphotype community composition together with growth response and biomass distribution in the arctic–alpine, prostrate willow Salix herbacea L. × Salix polaris Wahlenb. after 11 seasons of shading, warming, and fertilization at a fellfield in subarctic Sweden. The aim was to assess responses of the integrated plant–fungal system to long-term field experiments simulating expected environmental changes. Warming more than doubled aboveground S. herbacea × S. polaris biomass and shoot growth, whereas shading and nutrient addition had less influence on these variables. In shaded plants, adjustments at leaf level probably buffered major changes in plant biomass allocation. Fertilization increased the root mass fraction and changed root system morphology by decreasing the number of root tips per unit root mass. While no long-term changes in total ECM colonization (%ECM root tips) in response to the treatments were identified, ECM colonization in June just after snowmelt was positively correlated with root density. Changes in densities of potential host plants may therefore be of great importance for ECM colonization intensity in this ecosystem type. The ECM morphotype community changed through the season, and frequencies of some ECM morphotypes ( Cortinarius saturninus and Clavulina spp.) changed more with season than with the treatments. Warming only slightly affected ECM morphotype frequencies, which implies a balanced increase in root tip numbers of most ECM morphotypes in warmed plants. Fertilization changed ECM morphotype community composition mainly because of a decrease in Cenococcum geophilum frequency and an increase in Tomentella stuposa frequency. We hypothesize that a shift from drought stress-tolerant fungi towards a dominance of minerogenic fungi may take place if nutrient availability increases substantially because of anthropogenic disturbances.
Fine-scale vegetation distribution in a cool temperate peatland
Authors: Bubier Jill L. , Moore Tim R. , Crosby Gareth
Published: August 2006

Carbon (C) modeling and carbon dioxide (CO2) flux measurements in peatlands are dependent on the distribution and productivity of vegetation in a system with a high degree of spatial variability, often linked to the position of the water table. We tested the hypothesis that at a fine-scale (tens of metres) water table position exerts a strong control on species abundance, plant biomass, particularly photosynthetically active tissues, leaf area index (LAI), and areal foliar N and chlorophyll at Mer Bleue, a cool temperate peatland in eastern Canada. Total aboveground biomass ranged from 147 to 1011 g·m–2, with shrubs contributing between 42% and 72% of the total in the transects. We found significant (P < 0.05) positive relationships between foliar and total vascular plant biomass and mean water table position, and significant decreases in the shrub foliar:woody biomass ratio and moss biomass with a lower water table. However, there was no significant relationship between water table position and photosynthetically active tissues (vascular plant leaves and moss capitulum), ranging from 114 to 672 g·m–2) and the areal mass of N in these tissues, ranging from 1.5 to 6.7 g·m–2. Multivariate analyses of vegetation and environmental data showed that species distribution could be explained by both water table and chemistry gradients and that unimodal rather than linear responses best described the species and water table relationships. LAI ranged from 0.1 to over 3 and was correlated with both water table position and with vascular foliar biomass. Percent cover of shrubs was correlated with foliar biomass and LAI. Our results suggest that the less labour-intensive estimates of percent cover can be used to predict the vascular plant foliar biomass and LAI measurements. The lack of relationship between photosynthetically active tissues, tissue N concentrations, and water table may also explain the surprising lack of spatial variability in peak growing season eddy flux net ecosystem CO2exchange in three different areas of the peatland.
Effects of clearcut logging and tree species composition on the diversity and community composition of epigeous fruit bodies formed by ectomycorrhizal fungi
Authors: Durall Daniel M. , Gamiet Sharmin , Simard Suzanne W. , Kudrna Lenka , Sakakibara Stacey M.
Published: August 2006

The objective of this study was to examine the effects of stand age and tree species composition on the abundance, diversity, and community composition of epigeous fruit bodies formed by ectomycorrhizal (ECM) fungi in the Interior Cedar Hemlock zone of British Columbia. Fruit bodies were collected and identified in May, June, August, September, and October of 1996, 1997, 1998, and 1999 from transects located in new (5 year old) plantations and mature (75–125 year old) wild forests composed of relatively pure Betula papyrifera Marsh. (paper birch), relatively pure Pseudotsuga menziesii var. glauca (Beissn.) Franco (interior Douglas-fir), and mixtures of the two tree species. A total of 187 fungal taxa were collected during the study, of which 185 occurred in mature forests and only 17 occurred in the plantations. Thirty-four taxa were unique to mature predominantly birch forests, 35 were unique to mature predominantly Douglas-fir forests, 17 were unique to mixed mature forests, and 68 taxa were found in all three mature forest types. The abundance of fruit bodies in mature forests varied widely among sampling years and generally increased with annual precipitation. ECM species richness differed between stand ages but not among forest compositions in both plantations and mature forests. Lactarius glyciosmus , Hygrophorus eburneus var. eburneus , and Cortinarius armillatus were more abundant in mature birch than mature Douglas-fir forests. Lactarius torminosus , Leccinum scabrum var. scabrum , and Rozites caperatus were also found predominantly in mature birch and mixed forests, whereas Gomphidius subroseus was more abundant in Douglas-fir forests than in birch and mixed mature forests. Russula brevipes was also found predominantly in mature Douglas-fir and mixed forests. Our results indicate that clearcutting has a profound effect on abundance and composition of ECM fruit bodies, and that changes in forest tree species composition may lead to shifts in ECM fungal community composition.
Relative abundance of ectomycorrhizas in a managed loblolly pine (Pinus taeda) genetics plantation as determined through terminal restriction fragment length polymorphism profiles
Authors: Burke David J. , Martin Kendall J. , Rygiewicz Paul T. , Topa Mary A.
Published: August 2006

We examined the relationship between relative abundance of ectomycorrhizas in soil cores determined using morphotype tip counts and terminal restriction fragment length polymorphism (TRFLP) analysis. Root tips were harvested from a total of 120 soil cores collected from six family plots in a loblolly pine ( Pinus taeda L.) genetics plantation. Tips from each soil core were morphotyped based on physical characteristics, identified through TRFLP and sequence analysis, then pooled to reconstruct the ectomycorrhizal community within that core. The identity and relative abundance of specific ectomycorrhizas in each reconstructed community was then determined using TRFLP analysis of the internal transcribed spacer of the rRNA gene. Using TRFLP, we were able to detect 34 ectomycorrhizal phylotypes colonizing roots of loblolly pine. TRFLP peak area was an accurate approximation of the relative number of tips of each ectomycorrhizal type within a soil core. Relative abundance of each ectomycorrhiza as determined by TRFLP was used to describe their distribution in the pine plantation. Although there were no differences found in ectomycorrhizal richness and evenness among the six family plots, the two fertilized plots had generally lower levels of ectomycorrhizal richness and evenness as indicated by rank abundance curves. Our results suggest that TRFLP is a useful tool for describing the occurrence and distribution of ectomycorrhizas in environmental samples.
Impacts of forest fragmentation on the reproductive success of white spruce (Picea glauca)
Authors: O'Connell Lisa M. , Mosseler Alex , Rajora Om P.
Published: August 2006

The fragmentation of forests into small, isolated remnants may reduce pollen quantity and quality in natural plant populations. The reproductive success of white spruce ( Picea glauca (Moench) Voss) was assessed in a landscape fragmented by agriculture in northern Ontario, Canada. We sampled a total of 23 stands and 104 white spruce trees from three different stand size classes. Each sampled stand was separated by 250–3000 m from the nearest neighbouring stand. Reproductive success, measured as the number of filled seeds per cone, increased with stand size. The total number of seeds per cone, a measure that includes both filled and aborted seeds, also increased with stand size, suggesting that pollen receipt limits the number of seeds in a cone. The proportion of empty seeds (postzygotic abortions) was highest in the two smallest stand size classes, suggesting that inbreeding levels were also highest in these stands. We detected no difference in germination success, seedling growth, and growth of trees up to 10 years from seeds produced by trees from different stand size classes. These results suggest that inbred individuals are largely eliminated during the seed development stage. We estimated that a threshold population size of 180 trees is needed to reduce the negative effects of pollen limitation and inbreeding and maintain seed yields observed in large contiguous stands.
Intensive grazing by Barnacle geese depletes High Arctic seed bank
Authors: Kuijper D.P.J. , Bakker J.P. , Cooper E.J. , Ubels R. , Jónsdóttir I.S. , Loonen M.J.J.E.
Published: August 2006

Studies in the Canadian Arctic show dramatic effects of increased goose grazing on vegetation structure and soil conditions, but little is known of the role of goose grazing in the European Arctic. We focused on how geese might affect plant recruitment via effects on seed production and soil seed bank in High Arctic Svalbard. Experimental grazing by captive Barnacle geese ( Branta leucopsis (Bechstein, 1803)) decreased flower densities both at normal and at high grazing pressure. Geese showed a clear preference for reproductive rather than vegetative shoots. Soil samples collected inside and outside 7-year-old exclosures in an intensively goose-grazed area revealed significant effects on the germinable soil seed bank. The density of viable seeds in the top soil layer inside exclosures was six times higher than in grazed plots. Lower densities of viable seeds occurred in the basal than in the top layer but there was no difference in basal layer seed density between exclosed and grazed plots. This study shows that geese have strong effects on floral abundance and consequently on the seed bank. We argue that goose grazing in these systems influences the potential for recovery after a disturbance event and thus the long-term plant species diversity and dynamics.
Organic solvents for the glucocorticoid inducer dexamethasone: are they toxic and unnecessary in hydroponic systems?
Authors: Robison Mary M. , Smid Matthew P.L. , Wolyn David J.
Published: August 2006

Hydroponic cultivation systems provide convenient means of delivering chemical inducers of gene expression to transgenic plants. The glucocorticoid dexamethasone is a water-insoluble inducer and is usually prepared as a stock solution in an organic solvent before addition to the hydroponic nutrient solution. We investigated the effects of ethanol, methanol, and dimethyl sulfoxide (DMSO) on plant appearance and root bacterial growth in nonsterile hydroponic Arabidopsis thaliana (L.) Heynh. culture after 8 d of exposure to the solvent. Ethanol and methanol promoted root bacterial growth and visibly affected overall plant appearance at levels as low as 0.001%, and the effects increased in direct relation to alcohol concentration. DMSO promoted root bacterial growth to a lesser extent than the alcohols and plant appearance was negatively affected only at concentrations of DMSO above 0.01%, suggesting that DMSO may be the best solvent choice. We also demonstrated, however, that dexamethasone prepared as a suspension in water, without dissolution in an organic solvent, was completely effective at inducing transcription of the transgene, thus eliminating the potentially confounding effects of solvents in the interpretation of results.
Seed-transmitted beneficial endophytic Stagonospora sp. can penetrate the walls of the root epidermis, but does not proliferate in the cortex, of Phragmites australis
Authors: Gao Kexiang , Mendgen Kurt
Published: August 2006

Stagonospora sp. (4/99-1) is a beneficial endophytic fungus frequently transmitted by seeds of Phragmites australis [Cav.] Trin. ex Steudel. Here we show that this fungus also penetrates the root epidermis. At first, hyphae were attracted by the root and proliferated on the root surface, preferably over the anticlinal walls. Penetration occurred directly by undifferentiated hyphae or was facilitated by hyphopodia. Hyphal growth within the root was restricted to the walls of epidermal cells and the walls of the cells of the outermost cortical layer. Deeper growth by the fungus elicited wall appositions and ingress into the cytoplasm of cortical cells was blocked by papillae. In the rare cases, the fungus managed to penetrate into cortical cells, these reacted with necrosis. Immunological studies suggested that fungal material reached the host plasmalemma and may have been taken up by endocytotic events. Our observations explain the endophytic lifestyle of hyphae close to the epidermis and the restricted development within the cortex.
A chloroplast DNA hairpin structure provides useful phylogenetic data within tribe Senecioneae (Asteraceae)
Authors: Bain J.F. , Jansen R.K.
Published: August 2006

The distribution of an inversion associated with a small hairpin structure in the psbA–trnH intergenic spacer region of chloroplast DNA was surveyed to determine its phylogenetic utility within the tribe Senecioneae of the Asteraceae. Over 2000 sequences were examined from a wide range of angiosperms. Although the inversion is homoplasious in a number of taxonomic groups, including the Senecioneae, it still provides useful phylogenetic information, especially when point substitutions in both the stem and loop regions are scored along with the inversion. The presence of two nested inversions within the hairpin structure allows it to be treated as a partially ordered multistate character, adding to its potential utility as a phylogenetic marker.
The application of proteomics to plant biology: a review
Authors: Rampitsch Christof , Srinivasan Murali
Published: August 2006

The term proteomics, although still less than a decade old, is becoming commonplace in the vocabulary of biologists. Advances made in yeast and humans have been remarkable, sustained by equally remarkable progress in mass spectrometry, bioinformatics, and separation techniques. Progress in plants has been more recent, much of it in the model organisms Arabidopsis thaliana (L.) Heynh. and rice ( Oryza sativa L.), reflecting the tremendous advantage of a complete genomic sequence for proteomics endeavours. Other plants have also been the subject of investigation and this review deals with recent progress in proteomics under three main subheadings: total proteome studies, stress and post-translational modifications, and symbiotic plant–microbe interactions. Examples from the current literature are used to illustrate how proteomics can be used by itself or as part of a larger strategy to gain insight into the functioning of plants at the molecular level.
A new study ofMarrella splendens(Arthropoda, Marrellomorpha) from the Middle Cambrian Burgess Shale, British Columbia, Canada
Authors: García-Bellido Diego C , Collins Desmond H
Published: August 2006

Study of over 1000 specimens of Marrella splendens Walcott, 1912, out of the more than 9000 collected by the Royal Ontario Museum (ROM) since 1975, has produced new information on the anatomy, functional morphology, and behaviour of this most common arthropod in the Burgess Shale fauna. Among the new features recognized is the distinction between the alimentary canal and circulatory system; where the former is generally three-dimensional and slightly reflective, the latter never presents any relief and is very reflective. A larger range of size is now known, from 2.4 to 24.5 mm in length, with small individuals possessing 17 body segments to large specimens with more than 26 body segments, representing an almost complete ontogenetic series. The second pair of "antennae" is now interpreted as swimming appendages, since the five distal segments are dorsoventrally compressed, fringed with setae and with a considerable blood supply, providing a paddlelike appendage capable of producing a considerable propelling force. The ROM collections extend the geographical distribution of Marrella 13 km to the southeast and the stratigraphical range through the lowest five members of the Burgess Shale Formation.
Reconstructing sea-level change from the internal architecture of stromatolite reefs: an example from the Mesoproterozoic Sulky Formation, Dismal Lakes Group, arctic Canada
Authors: Kah Linda C , Bartley Julie K , Frank Tracy D , Lyons Timothy W
Published: August 2006

The Mesoproterozoic Dismal Lakes Group, arctic Canada, contains a relatively thin, yet regionally extensive stromatolitic reef complex that developed subtidally during a major transgression, shoaled to sea level, and was overlain by intertidal to supratidal carbonate and evaporite strata. The September Lake reef complex exhibits a complex internal architecture that records the interaction between stromatolite growth and changes in accommodation space derived from both higher order (4th- or 5th-order, parasequence-scale) changes in sea level and the variable bathymetry of the sea floor. Reef growth, which was initiated during three sea-level cycles, records progressive marine transgression over depositional lows that were formed during pre-reef subaerial exposure and erosion of the underlying strata. A fourth sea-level cycle, represented by spectacular coniform stromatolites with >10 m of synoptic relief, marks a more dramatic rise in sea level and establishment of the main reef complex. Aggradation and eventual shoaling of the reef complex occurred over an additional six sea-level cycles. Only basinward regions of the September Lake reef complex preserve vertical stacking of reefal packages in response to sea-level fluctuations. In contrast, in the main reef core, sea-level fluctuations resulted in subaerial exposure of the reef top, variable karst development, and the progressive infilling of reef topography by progradational reef elements. Assessment of stromatolite growth patterns reveals the complex nature of the reef architecture and permits the determination of higher order changes in relative sea level that were responsible for reef development.
Middle Turonian dinosaur paleoenvironments in the Upper Cretaceous Kaskapau Formation, northeast British Columbia
Authors: Rylaarsdam Jessica R , Varban Bogdan L , Plint A Guy , Buckley Lisa G , McCrea Richard T
Published: August 2006

The Kaskapau Formation is a mudstone-dominated wedge up to 950 m thick that spans late Cenomanian to middle Turonian time. The formation has a prominent wedge geometry and was deposited in the foredeep of the Western Canada Foreland Basin. In outcrop in northeast British Columbia, nearshore sandstones are locally well developed and include rare wedges of nonmarine strata. On Quality Creek, near Tumbler Ridge, 11 m of nonmarine strata contain abundant dinosaur tracks and the first in situ dinosaur bone reported from British Columbia. This site, at a paleolatitude of about 67°N, preserves a rare glimpse of Turonian terrestrial environments during global eustatic highstand. Three main dinosaur habitats are recognized: strandplain and beach-ridge; freshwater lake; and brackish lagoon. Back-beach sandstone has a relief of about 2.5 m, interpreted as beach ridges; sandy coals containing abundant dinosaur tracks represent inter-ridge slough deposits. Overlying lake deposits comprising laminated muds with freshwater molluscs grade up into rooted muddy siltstone and locally, dinoturbated sandstone. Lake deposits are capped by lagoonal mudstone with abundant brackish-water molluscs, locally including a dinosaur-trampled oyster bioherm. The upper parts of sandy lagoonal deltas are pervasively dinoturbated. Sandstone filling a tidal channel contains logs, oyster shells, and bones of dinosaurs, turtles, and crocodiles, as well as fish scales. The lagoonal succession is erosively overlain by offshore sandy mudstones. Various lines of evidence suggest that the mean annual temperature at this sea-level location was about 14 °C, with a cold-month mean no less than 5.5 °C. The high-latitude location implies a significant period of winter darkness, and correspondingly diminished plant productivity.
Evidence for catastrophic volcanic debris flows in Pemberton Valley, British Columbia
Authors: Simpson K A , Stasiuk M , Shimamura K , Clague J J , Friele P
Published: August 2006

The Mount Meager volcanic complex in southern British Columbia is snow and ice covered and has steep glaciated and unstable slopes of hydrothermally altered volcanic deposits. Three large-volume (>108 m3) volcanic debris flow deposits derived from the Mount Meager volcanic complex have been identified. The volcanic debris flows travelled at least 30 km downstream from the volcanic complex and inundated now populated areas of Pemberton Valley. Clay content and mineralogy of the deposits indicate that the volcanic debris flows were clay-rich (5%–7% clay in the matrix) and derived from hydrothermally altered volcanic material. The youngest volcanic debris flow deposit is interpreted to be associated with the last known volcanic eruption, ~2360 calendar (cal) years BP. The other two debris flows may not have been directly associated with eruptions. Volcanic debris flow hazard inundation maps have been produced using the Geographic Information System (GIS)-based modelling program, LAHARZ. The maps provide estimates of the areas that would be inundated by future moderate to large-magnitude events. Given the available data, the probability of a volcanic debris flow reaching populated areas in Pemberton Valley is ~1 in 2400 years. Additional mapping in the source regions is necessary to determine if sufficient material remains on the volcanic edifice to generate future large-magnitude, clay-rich volcanic debris flows.
The influence of siting and deterrence methods on seal predation at Atlantic salmon (Salmo salar) farms in Maine, 2001–2003
Authors: Nelson Marcy L , Gilbert James R , Boyle Kevin J
Published: August 2006

We document the nature and frequency of seal predation at Atlantic salmon (Salmo salar) farms in Maine and determine whether the severity of predation is related to the proximity of farms from one another and nearby harbor seal (Phoca vitulina concolor) haul-outs. We surveyed farm managers annually from 2001–2003 to document management techniques, husbandry practices, and predator deterrence methods employed for comparison with the extent of seal predation. Biweekly aerial surveys were conducted between January and March of each year to document harbor seal presence. An empirical estimate from a negative binomial model showed seal predation at farms declined significantly with distance to the nearest haul-out, suggesting that seal predation may be deterred by maximizing the distance between farms and seal haul-outs. Farms located further than 4 km from harbor seal haul-outs experienced minimal losses. At farms located within 4 km of harbor seal haul-outs, seal predation decreased with increasing distance from neighboring farms, indicating that areas where farms are concentrated may be more vulnerable. The regular replacement of primary and secondary cage netting was negatively correlated with seal predation. Finally, this study documents the apparent ineffectiveness of acoustic harassment devices at deterring seal predation.
The influence of prey availability on ontogenetic diet shifts of a juvenile piscivore
Authors: Galarowicz Tracy L , Adams Julie A , Wahl David H
Published: August 2006

Young-of-year piscivores typically undergo ontogenetic diet shifts from planktivory to benthivory to piscivory. These shifts are often the result of changes in predator foraging abilities, but little is known about the influence of relative prey availability. As a result, we examined diet shifts across a range of sizes (20–150 mm) of a young-of-year piscivore, walleye (Sander vitreus), in feeding experiments in which zooplankton, benthic invertebrates, and fish were made available at different density combinations. Consumption of each prey type changed with walleye size and prey densities. Small juveniles (20 mm) selected zooplankton and fish, whereas larger walleye (40–100 mm) selected benthic invertebrates and fish. Relative prey densities influenced consumption; increased densities of more profitable prey types resulted in reduced consumption of less profitable prey. Walleye larger than 100 mm selected only fish. Foraging efficiencies also varied with size and prey types; small walleye (20 mm) were less likely to pursue benthic invertebrates and retain captured fish. These ontogenetic changes in foraging patterns are linked to prey profitability, have growth consequences for juvenile walleye, and have implications for understanding diet shifts of other juvenile fish.
Olfactory inhibition and recovery in chum salmon (Oncorhynchus keta) following copper exposure
Authors: Sandahl Jason F , Miyasaka Go , Koide Nobuhisa , Ueda Hiroshi
Published: August 2006

Copper can be an effective hatchery treatment to control certain parasitic and fungal infections in salmonids, yet it is also highly toxic to the fish's olfactory system. Numerous reports have described the early inhibitory impacts of copper on fish olfaction, but very few have addressed processes of recovery. Here we show that the chum salmon (Oncorhynchus keta) olfactory system can recover from short-term (4 h) exposures to copper (3–58 µg·L–1) within 1 day, as indicated by electro-olfactogram (EOG) recordings. Recovery followed initial EOG reductions of up to 88%. We also applied a novel cytophysiological approach to monitor changes in the olfactory receptor cells using a fluorescent styryl dye, AM1-43. Copper's influence on the number of receptor cells that labelled with the dye was biphasic, initially increasing the number at the two lowest copper concentrations (3 and 8 µg·L–1) and decreasing the number at the two highest concentrations (24 and 58 µg·L–1). Changes in the ability of olfactory receptor neurons to internalize the dye were monitored up to 10 days in fish recovering from copper exposure.
Estimation of seabird bycatch for North Pacific longline vessels using design- and model-based methods
Authors: Miller T J , Skalski J R
Published: August 2006

Bycatch estimation for sensitive species is becoming increasingly important with the shift toward an ecosystem-based approach to fisheries management. Incidental mortalities for various seabird species occur on longline vessels throughout the world, including those in the North Pacific groundfish fleet. We present an approach to seabird bycatch estimation for North Pacific longline vessels using observer-collected data. Observers collect enormous amounts of data through a complex sampling design, but some information deficiencies preclude bycatch estimation using only probability sampling. Our approach combines probability sampling with model-dependent techniques to overcome these information deficiencies. The resulting bycatch estimator reflects the observer sampling design as closely as possible and minimizes reliance on untested model assumptions. We apply our estimator to black-footed albatross (Phoebastria nigripes) bycatch as an example and compare yearly estimates to those previously published. We also suggest changes in data collection that would further reduce dependence on model assumptions.
Short-term responses to watershed logging on biomass mercury and methylmercury accumulation by periphyton in boreal lakes
Authors: Desrosiers Mélanie , Planas Dolors , Mucci Alfonso
Published: August 2006

In the boreal forest, watershed logging may increase runoff, as well as chemical loading, including nutrient, dissolved organic carbon, and mercury, to lakes. Because they are exposed directly to nutrients and contaminants exported from the watershed, littoral communities such as periphyton may respond quickly to watershed disturbances. The objectives of this study were to evaluate the response of periphyton to watershed logging using a BACI (before–after control–impact) statistical approach and to develop a predictive tool to facilitate the elaboration of practical logging policies aimed at reducing Hg loading to lakes. In this study, we compare the periphyton biomass in 18 boreal Canadian Shield lakes, as well as their total mercury and methylmercury levels. During the ice-free season from 2000 to 2002, eight of these lakes were monitored before and after logging, with the other 10 lakes serving as controls. The BACI statistical analyses reveal a significant impact of logging on periphyton biomass (decrease; 0.6- to 1.5-fold) and methylmercury accumulation (increase; 2- to 9.6-fold). This study demonstrates that periphyton responds quickly to disturbances of the watershed. Our results suggest that the periphyton and watershed characteristics could serve as good management tools and that logging should be limited in watersheds with a mean slope below 7.0%.