Effects of Watershed Land use on Nitrogen Concentrations and δ 15 Nitrogen in Groundwater

Eutrophication is a major agent of change affecting freshwater, estuarine, and marine systems. It is largely driven by transportation of nitrogen from natural and anthropogenic sources. Research is needed to quantify this nitrogen delivery and to link the delivery to specific land-derived sources. In this study we measured nitrogen concentrations and δ¹⁵N values in seepage water entering three freshwater ponds and six estuaries on Cape Cod, Massachusetts and assessed how they varied with different types of land use. Nitrate concentrations and δ¹⁵N values in groundwater reflected land use in developed and pristine watersheds. In particular, watersheds with larger populations delivered larger nitrate loads with higher δ¹⁵N values to receiving waters. The enriched δ¹⁵N values confirmed nitrogen loading model results identifying wastewater contributions from septic tanks as the major N source. Furthermore, it was apparent that N coastal sources had a relatively larger impact on the N loads and isotopic signatures than did inland N sources further upstream in the watersheds. This finding suggests that management priorities could focus on coastal sources as a first course of action. This would require management constraints on a much smaller population.     

Vitis vinifera root and leaf metabolic composition during fruit maturation: implications of defoliation

Grapevine (Vitis vinifera) roots and leaves represent major carbohydrate and nitrogen (N) sources, either as recent assimilates, or mobilized from labile or storage pools. This study examined the response of root and leaf primary metabolism following defoliation treatments applied to fruiting vines during ripening. The objective was to link alterations in root and leaf metabolism to carbohydrate and N source functioning under conditions of increased fruit sink demand. Potted grapevine leaf area was adjusted near the start of véraison to 25 primary leaves per vine compared to 100 leaves for the control. An additional group of vines were completely defoliated. Fruit sugar and N content development was assessed, and root and leaf starch and N concentrations determined. An untargeted GC/MS approach was undertaken to evaluate root and leaf primary metabolite concentrations. Partial and full defoliation increased root carbohydrate source contribution towards berry sugar accumulation, evident through starch remobilization. Furthermore, root myo‐inositol metabolism played a distinct role during carbohydrate remobilization. Full defoliation induced shikimate pathway derived aromatic amino acid accumulation in roots, while arginine accumulated after full and partial defoliation. Likewise, various leaf amino acids accumulated after partial defoliation. These results suggest elevated root and leaf amino N source activity when leaf N availability is restricted during fruit ripening. Overall, this study provides novel information regarding the impact of leaf source restriction, on metabolic compositions of major carbohydrate and N sources during berry maturation. These results enhance the understanding of source organ carbon and N metabolism during fruit maturation.     

Determination of genetic variability among the isolates of <Emphasis Type="Italic">Metarhizium anisopliae</Emphasis> var. <Emphasis Type="Italic">anisopliae</Emphasis> from different geographical origins

The entomopathogenic fungus Metarhizium anisopliae is currently used as an efficient biological control agent against different insects. The prevalence and genetic variability of the entomopathogenic fungus Metarhizium anisopliae var. anisopliae in Asian countries (China, Laos, Singapore and South Korea) and a European country (The Netherlands) was examined. The fungus was found to be widespread in agricultural and forest soils throughout China especially in the south and south western regions, with a maximum recovery percentage of 81.6, while in Laos it was found to be abundant in the forest soils only, the soil of Netherlands also seemed to be an excellent source of entomopathogens with a significant recovery of insect pathogenic fungi. Simple sequence repeats (SSR) and ITS-rDNA sequence data showed that the isolates are closely linked to each other. The gene diversity (He) and polymorphic information content values of sixty two isolates showed mean values of 0.37 and 0.63. The majority of the isolates belonged to one of the closely related genotypes and these were found to be dominant in the agricultural as well as forest ecosystem. Genetic distances among the isolates according to locations and different sources showed minimal variation ranging from 0.23 to 0.34%, with maximum genetic distance of 0.34% among the isolates from Laos and The Netherlands. The reason for the limited variation is uncertain, however even the similarity index among the isolates can endow with sufficient knowledge for the implications of the methods to develop this fungus as a microbial control agent.     

Molecular regulation of sink–source transition in rice leaf sheaths during the heading period

The upper leaf sheath of rice (Oryza sativa L.) serves as a temporary starch sink before heading, subsequently becoming a carbon source tissue to the growing panicle at the post-heading stage. The time of sink–source transition in upper leaf sheaths is highly correlated to the panicle exsertion. Here, we found that the expression profiles of starch synthesis genes such as ADP-glucose pyrophosphorylase large subunit 2, granule-bound starch synthase II, soluble starch synthase I, starch branching enzyme (SBE) I, SBEIII, and SBEIV were highly correlated with starch content changes during the heading period in the second leaf sheath below the flag leaf. In addition, the α-amylase2A and β-amylase were considered as major genes that were in charge of starch degradation at the post-heading period. Of the five sucrose transporter (OsSUT) genes, OsSUT1 and OsSUT4 appeared to play an important role in sucrose loading into the phloem of source leaf sheaths. Moreover, the microarray-based data implied that the dominant processes associated with functional leaf sheath transition from sink to source were carbohydrate metabolism and the translocation of the carbon and nitrogen sources and inorganic phosphate.     

Antibacterial activity of a bacteriocin-like substance produced by Bacillus sp. P34 that targets the bacterial cell envelope

The objective of this study was to investigate the mode of action of BLS P34, a bacteriocin-like substance (BLS) produced by a novel Bacillus sp. strain P34 isolated from the Amazon basin. The effect of the BLS was tested against Listeria monocytogenes, showing a bactericidal effect at 200 AU (activity units) ml⁻¹, while no inhibition of spore outgrowth of Bacillus cereus was observed with a dose of 1,600 AU ml⁻¹. Growth of Escherichia coli and Salmonella Enteritidis was inhibited, but only when the chelating agent EDTA was co-added with the BLS. The effect of BLS P34 on L. monocytogenes was also investigated by Fourier transform infrared spectroscopy. Treated cells showed an important frequency increase in 1,452 and 1,397 cm⁻¹ and decrease in 1,217 and 1,058 cm⁻¹, corresponding assignments of fatty acids and phospholipids. Transmission electron microscopy showed damaged cell envelope and loss of protoplasmic material. BLS P34 was bactericidal to Gram-positive, and also showed inhibitory effect against Gram-negative bacteria. There is evidence that its mode of action corresponds to that of a membrane-active substance. The knowledge about the mode of action of this BLS is essential to determine its effective application as an antimicrobial agent.     

Evaluation of Electroencephalography Source Localization Algorithms with Multiple Cortical Sources

Background

Source localization algorithms often show multiple active cortical areas as the source of electroencephalography (EEG). Yet, there is little data quantifying the accuracy of these results. In this paper, the performance of current source density source localization algorithms for the detection of multiple cortical sources of EEG data has been characterized.

Methods

EEG data were generated by simulating multiple cortical sources (2–4) with the same strength or two sources with relative strength ratios of 1:1 to 4:1, and adding noise. These data were used to reconstruct the cortical sources using current source density (CSD) algorithms: sLORETA, MNLS, and LORETA using a p-norm with p equal to 1, 1.5 and 2. Precision (percentage of the reconstructed activity corresponding to simulated activity) and Recall (percentage of the simulated sources reconstructed) of each of the CSD algorithms were calculated.

Results

While sLORETA has the best performance when only one source is present, when two or more sources are present LORETA with p equal to 1.5 performs better. When the relative strength of one of the sources is decreased, all algorithms have more difficulty reconstructing that source. However, LORETA 1.5 continues to outperform other algorithms. If only the strongest source is of interest sLORETA is recommended, while LORETA with p equal to 1.5 is recommended if two or more of the cortical sources are of interest. These results provide guidance for choosing a CSD algorithm to locate multiple cortical sources of EEG and for interpreting the results of these algorithms.     

Carbon,nitrogen and pH regulate the production and activity of a polygalacturonase isozyme produced by Penicillium expansum

The influence of carbon, nitrogen and pH on polygalacturonase (PG) activity produced by Penicillium expansum were investigated. P. expansum mycelial growth was greatest on lyophilized lyophilised fruit tissue and the highest PG activity occurred in apple pectin medium. Nitrogen source influenced PG activity and was highest with ammonia while the greatest mycelial mass was supported by glutamate or glutamine. PG activity and mycelial mass peaked 5 five days after inoculation as polyuronide content decreased and the pH and ammonium levels increased in apple pectin medium. A single active PG isozyme with an isoelectric point of ～7.6 was produced in apple pectin medium and a partial cDNA clone was obtained that was most homologous to the pggII gene from Penicillium. griseoroseum. The results from this study indicate that P. expansum can modulate the activity of PG in response to nutrient sources and ambient pH through signalling pathways that modulate nutrient acquisition, uptake and metabolism.     

Effect of Silibinin on the Activity and Expression of Superoxide Dismutase in Lymphocytes from Patients with Chronic Alcoholic Liver Disease

The in vitro and in vivo effects of the naturally occuring Ravolignan hepatoprotective agent silibinin? on the expression and activity of superoxide dismutase (SOD) enzyme were studied in lymphocytes from patients with chronic alcoholic liver disease. In vitro incubation with silibinin in a concentration corresponding to the usual therapeutic dosage markedly increased the SOD — expression of lymphocytes as measured by Row-cytofluorimetry following staining with monoclonal anti-Cu, Zn-SOD — antibody and FITC-conjugated anti-mouse Ig. In vivo treatment with the drug restored the originally low SOD activity of the patients' lymphocytes. These data indirectly suggest that antioxidant activity might be one of the important factors in the hepatoprotective action of silibinin.     

Degradation of nitrocellulose by fungi

Three lignocellulolytic fungi, Trametes versicolor, Pleurotus ostreatus, and Coprinus cinereus, and two cellulolytic fungi Trichoderma reesei andChaetomium elatum were tested for their ability to degrade nitrocellulose. They were provided with different carbon and nitrogen sources in liquid cultures. Nitrocellulose (N content above 12%) was added as nitrogen source (in solution in acetone) alongside amino acids or as sole N source. Either starch or carboxy-methyl cellulose were provided as carbon sources. After 28 days of growth the highest decrease of nitrocellulose was observed with Chaetomium elatum when up to 43% was degraded in a medium containing nitrocellulose as the only nitrogen source. Coprinus cinereus caused a 37% decrease of nitrocellulose when provided with amino acids and starch as co-substrate. In cultures of Trametes versicolor, Pleurotus ostreatus andTrichoderma reesei, only 10%–22% decrease of nitrocellulose was measured in all media. In the presence of nitrocellulose with N content below 12% supplied as 3 mm pellets as the only carbon source, or with nitrocellulose with carboxy-methyl cellulose, the release of nitrite and nitrate from liquid cultures of Chaetomium elatum was measured. Between 6 and 9 days of growth in these media, an increase in both nitrite and nitrate was observed with a loss in weight of nitrocellulose up to 6% achieved after 34 days. The physical nature of the NC pellets may have reduced the rate of degradation in comparison with supplying NC in solution in the cultures.     

The relative importance of sediment and water column supplies of nutrients to the growth and tissue nutrient content of the green macroalga Enteromorpha intestinalis along an estuarine resource gradient

Large blooms of opportunistic green macroalgae such as Enteromorpha intestinalis are of ecological concern in estuaries worldwide. Macroalgae derive their nutrients from the water column but estuarine sediments may also be an important nutrient source. We hypothesized that the importance of these nutrient sources to E. intestinalis varies along a nutrient-resource gradient within an estuary. We tested this in experimental units constructed with water and sediments collected from 3 sites in Upper Newport Bay estuary, California, US, that varied greatly in water column nutrient concentrations. For each site there were three treatments: sediments + water; sediments + water + Enteromorpha intestinalis (algae); inert sand + water + algae. Water in units was exchanged weekly simulating low turnover characteristic of poorly flushed estuaries. The importance of the water column versus sediments as a source of nutrients to E. intestinalis varied with the magnitude of the different sources. When initial water column levels of dissolved inorganic nitrogen (DIN) and soluble reactive phosphorus (SRP) were low, estuarine sediments increased E. intestinalis growth and tissue nutrient content. In experimental units from sites where initial water column DIN was high, there was no effect of estuarine sediments on E. intestinalis growth or tissue N content. Salinity, however, was low in these units and may have inhibited growth. E. intestinalis growth and tissue P content were highest in units from the site with highest initial sediment nutrient content. Water column DIN was depleted each week of the experiment. Thus, the water column was a primary source of nutrients to the algae when water column nutrient supply was high, and the sediments supplemented nutrient supply to the algae when water column nutrient sources were low. Depletion of water column DIN in sediment + water units indicated that the sediments may have acted as a nutrient sink in the absence of macroalgae. Our data provide direct experimental evidence that macroalgae utilize and ecologically benefit from nutrients stored in estuarine sediments.     

Filial Cannibalism in the Paternal Mouthbrooding Cardinalfish Apogon lineatus: Egg Production by the Female as the Nutrition Source for the Mouthbrooding Male

We investigated about filial cannibalism by Apogon lineatus based on 25 mouthbrooding males sampled in Tokyo Bay, Japan. Eggs were found in the stomachs of all mouthbrooding males, indicating that Apogon lineatus performs partial brood cannibalism. The number of eggs in the stomachs ranged from 1015 to 9384, corresponding to 30% on average of the entire brood. This study revealed that mouthbrooding males could gain considerable energy by partial brood cannibalism during brood periods, that is, females would produce surplus eggs as the nutrition sources for starving males.     

Sucrose-phosphate synthase responds differently to source-sink relations and to photosynthetic rates: Lolium perenne L. growing at elevated pCO2 in the field

Lolium perenne, a main component species in managed grassland, is well adapted to defoliation, fertilization, and regrowth cycles; and hence, to changes in the assimilatory carbon source‐sink ratio. In the Swiss Free Air CO₂ Enrichment experiment the source‐sink ratio is (i) increased by elevated partial pressure of CO₂ (p_CO2), (ii) decreased by enhanced carbon use under high N fertilization, and (iii) gradually increased during regrowth after defoliation. Since sucrose synthesis plays a central role in leaf carbohydrate metabolism in this fructan‐accumulating species, we investigated how sucrose‐phosphate synthase (SPS) responds to the differing assimilatory carbon fluxes and source‐sink ratios in the field. Assimilatory carbon flux, as estimated by leaf gas exchange, strongly depended on p_CO2. Surprisingly, the SPS content per leaf area did not increase with p_CO2, but increased with N fertilization. During later regrowth, when a dense canopy had formed, the SPS content decreased; in particular, SPS was decreased at high N under elevated p_CO2. Further, the higher assimilatory carbon flux through SPS at elevated p_CO2 was accompanied by a higher activation state of SPS. The SPS content correlated very strongly with the ratio of free sucrose to free amino acid in leaves, which represents the carbon source‐sink ratio. Hence, SPS content in L. perenne appears to be regulated by the current, strongly nitrogen‐dependent, source‐sink relation.     

The impact of supplemental carbon sources on <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> growth,chlorophyll content and anthocyanin accumulation

This research explores the impacts of a broad range of supplemental carbon sources on growth and development of Arabidopsis thaliana. Parameters measured include dark-germinated hypocotyl length, light-germinated root growth, rosette growth, chlorophyll concentration and anthocyanin content. Treatment sugars include sucrose, maltose, d-glucose, d-fructose, l-arabinose, l-fucose, d-galactose, d-mannose, l-rhamnose and d-xylose each supplied at 4, 20 or 100 mM. This comparison of the effect of different carbon sources on multiple parameters and under identical conditions showed that every carbon source had unique qualitative and quantitative effects on Arabidopsis growth and development. Root growth was particularly sensitive to supplemental carbon source. Growth on 100 mM sucrose, maltose, glucose or xylose stimulated root growth by ~100%. Growth on arabinose, fucose, galactose, mannose or rhamnose inhibited root growth by 50% or more. Several sugars that strongly inhibited root growth had either no effect (galactose and fucose) or a positive effect (arabinose) on hypocotyl elongation and rosette growth. Rhamnose was the only carbon source that inhibited hypocotyl elongation across all concentrations. Sucrose, maltose, glucose, fructose, arabinose or xylose stimulated rosette growth by ~50%. Chlorophyll content was strongly reduced by mannose while sucrose, glucose, galactose and rhamnose caused smaller reductions. Anthocyanin accumulation was strongly induced by both galactose and mannose. Only mannose impacted all parameters across all concentrations. Based on these data it can be concluded that the effect of each carbon source on Arabidopsis growth and development is specific in terms of both magnitude and the parameters impacted.     

Patterns of sugar feeding and host plant preferences in adult males of An. gambiae (Diptera: Culicidae)

Sugar feeding by male mosquitoes is critical for their success in mating competition . However, the facets of sugar source finding under natural conditions remain unknown. Here, evidence obtained in Western Burkina Faso indicated that the distribution of An. gambiae s.s. (M and S molecular forms) males across different peri‐domestic habitats is dependent on the availability of potential sugar sources from which they obtain more favorable sites for feeding or resting. Among field‐collected anophelines, a higher proportion of specimens containing fructose were found on flowering Mangifera indica (Anacardiaceae), Dolonix regia (Fabaceae), Thevetia neriifolia (Apocynaceae), Senna siamea, and Cassia sieberiana (both Fabaceae) compared to that recorded on other nearby plants, suggesting that some plants are favored for use as a sugar source over others. Y‐tube olfactometer assays with newly‐emerged An. gambiae s.s. exposed to odors from individual plants and some combinations thereof showed that males use odor cues to guide their preference. The number of sugar‐positive males was variable in a no‐choice cage assay, consistent with the olfactory response patterns towards corresponding odor stimuli. T hese experiments provide the first evidence both in field and laboratory conditions for previously unstudied interactions between males of An. gambiae and natural sugar sources.     

Orexinergic Neurotransmission in Temperature Responses to Methamphetamine and Stress: Mathematical Modeling as a Data Assimilation Approach

Experimental Data

Orexinergic neurotransmission is involved in mediating temperature responses to methamphetamine (Meth). In experiments in rats, SB-334867 (SB), an antagonist of orexin receptors (OX1R), at a dose of 10 mg/kg decreases late temperature responses (t>60 min) to an intermediate dose of Meth (5 mg/kg). A higher dose of SB (30 mg/kg) attenuates temperature responses to low dose (1 mg/kg) of Meth and to stress. In contrast, it significantly exaggerates early responses (t<60 min) to intermediate and high doses (5 and 10 mg/kg) of Meth. As pretreatment with SB also inhibits temperature response to the stress of injection, traditional statistical analysis of temperature responses is difficult.

Mathematical Modeling

We have developed a mathematical model that explains the complexity of temperature responses to Meth as the interplay between excitatory and inhibitory nodes. We have extended the developed model to include the stress of manipulations and the effects of SB. Stress is synergistic with Meth on the action on excitatory node. Orexin receptors mediate an activation of on both excitatory and inhibitory nodes by low doses of Meth, but not on the node activated by high doses (HD). Exaggeration of early responses to high doses of Meth involves disinhibition: low dose of SB decreases tonic inhibition of HD and lowers the activation threshold, while the higher dose suppresses the inhibitory component. Using a modeling approach to data assimilation appears efficient in separating individual components of complex response with statistical analysis unachievable by traditional data processing methods.     

Activity of triadimefon vapour against Erysiphe graminis f. sp. hordei

A series of experiments from 1978 to 1983 investigated the activity of triadimefon vapour against barley powdery mildew (Erysiphe graminis f. sp. hordei). In early experiments there was a pronounced protectant action when the dry product was used as the vapour source, and this protection persisted after test seedlings had been removed from the vicinity of the vapour source. In a glasshouse, sprayed seedlings remained sources of active vapour for at least 6 wk after spraying. In later experiments, effects of triadimefon vapour were much smaller, probably because the pathogen had become less sensitive to the fungicide. The dry product was no longer an effective vapour source but infection of test seedlings was still decreased if they were exposed to vapour emanating from impregnated absorbent paper or sprayed seedlings, presumably because the effective surface areas were much greater. Possible benefits and problems that arise from vapour action in glasshouse and field experiments are discussed.     

Spatial orientation in the bushcricket <Emphasis Type="Italic">Leptophyes punctatissima</Emphasis> (Phaneropterinae; Orthoptera): III. Peripheral directionality and central nervous processing of spatial cues

We examined peripheral and central nervous cues underlying the ability of the bushcricket Leptophyes punctatissima to orient to elevated and depressed sound sources broadcasting the female acoustic reply. The peripheral spatial directionality of the ear was measured physiologically using monaural preparations of an auditory interneuron (T-fibre). In the azimuth, maximal interaural intensity differences of 18 dB occur between ipsi- and contralateral stimulation. With increasing elevation or depression of the sound sources, IIDs decrease systematically and reach zero with the source exactly above or below the preparation. Bilateral, simultaneous recordings of the activity of the pair of interneurons allowed determining the binaural discharge differences which occur in response to the extremely short (1 ms) female reply. These discharge differences are large (four action potentials/stimulus) and reliable in the azimuth with lateral stimulation, and decrease gradually with more frontal stimulation. With elevation and depression of sound sources these differences again decrease to one action potential/stimulus at 60° or 75° elevation, and lateral stimulus angles of about 60°. We also calculated the reliability with which a receiver could correctly determine the location of the sound source. We discuss these quantitative measures in relation to the spatial phonotactic behaviour of male L. punctatissima.     

An anchored linkage map for sugar beet based on AFLP,SNP and RAPD markers and QTL mapping of a new source of resistance to <Emphasis Type="Italic">Beet necrotic yellow vein virus</Emphasis>

Rhizomania, caused by Beet necrotic yellow vein virus (BNYVV), is an important sugar-beet disease worldwide and can result in severe losses of root yield and sugar content. We have identified a major QTL for BNYVV resistance from a new source in a segregating population of 158 individuals. The QTL explained an estimated 78% of the observed phenotypic variation and the gene conferring the partial resistance is referred to as Rz4. AFLP was used in combination with bulked segregant analysis (BSA) to develop markers linked to the resistance phenotype. AFLP marker analysis was extended to produce a linkage map that was resolved into nine linkage groups. These were anchored to the nine sugar-beet chromosomes using previously published SNP markers. This represents the first anchored sugar-beet linkage map to be published with non-anonymous markers. The final linkage map comprised 233 markers covering 497.2 cM, with an average interval between markers of 2.1 cM. The Rz4 QTL and an Rz1 RAPD marker were mapped to chromosome III, the known location of the previously identified BNYVV resistance genes Rz1, Rz2 and Rz3. The availability to breeders of new resistance sources such as Rz4 increases the potential for breeding durable disease resistance.