Showing papers by "University of Hohenheim published in 1996"
TL;DR: The widely used TBA assay for lipid peroxidation was modified to minimize artefactual oxidative degradation of lipids during the assay, and the concentration effect of BHT addition was examined.
708 citations
TL;DR: Root growth is enhanced under nitrogen and phosphorus deficiencies, but not under deficiencies of nutrients of low mobility in the phloem, such as calcium and boron, as demonstrated in impaired export under magnesium, potassium, or zinc deficiencies.
Abstract: Mineral nutrients taken up by the roots are, as a rule, transported in the xylem to the shoot, and photoassimilates transported in the phloem to the roots. According to the Thornley model of photosynthate partitioning, nutrient deficiencies should favour photosynthate partitioning to the roots. Examples are cited to show that this preferential partitioning is dependent on phloem mobility and hence on nutrient cycling from shoot to roots. Thus, root growth is enhanced under nitrogen and phosphorus deficiencies, but not under deficiencies of nutrients of low mobility in the phloem, such as calcium and boron. Enhanced root growth under nutrient deficiency relies on the import of both photosynthates and mineral nutrients. Cycling of mineral nutrients serves a number of other functions. These include the root supply of nutrients assimilated in the shoot (nitrate and sulphate reduction), maintenance of cation-anion balance in the shoot, providing an additional driving force for solute volume flow in the phloem and xylem, and acting as a shoot signal to convey nutrient demand to the root. Cycling of certain mineral nutrients through source leaves has a considerable impact on photosynthate export as demonstrated in impaired export under magnesium, potassium, or zinc deficiencies. Mineral nutrient deficiency can, therefore, affect photosynthate partitioning either directly via phloem loading and transport or indirectly by depressing sink demand.
573 citations
TL;DR: In this article, Moringa oleifera leaves were extracted and unextracted from aqueous ethanol and the true protein contents of these leaves were 93.8% and 81.1% respectively.
537 citations
TL;DR: A 150-year-long cooling in the early Preboreal, associated with rising Δ14C values, is evident in all records and indicates an ocean ventilation change, and box-model calculations suggest that they all may have been the result of increased freshwater forcing that inhibited the strength of the North Atlantic heat conveyor.
Abstract: On the basis of synchronization of three carbon-14 (C-14)-dated lacustrine sequences from Sweden With tree ring and ice core records, the absolute age of the Younger Dryas-Preboreal climatic shift was determined to be 11,450 to 11,390 +/- 80 years before the present. A 150-year-long cooling in the early Preboreal, associated with rising Delta(14)C values, is evident in all records and indicates an ocean ventilation change. This cooling is similar to earlier deglacial coolings, and box-model calculations suggest that they all may have been the result of increased freshwater forcing that inhibited the strength of the North Atlantic heat conveyor, although the Younger Dryas may have begun as an anomalous meltwater event.
511 citations
TL;DR: Two pathways for the uptake of Zn from Zn-phytosiderophores in grasses are proposed, one via the transport of the free Zn cation and the other via the uptake with increasing stability constant of the chelate.
Abstract: To investigate the recognition of Zn-phytosiderophores by the putative Fe-phytosiderophore transporter in maize (Zea mays L.) roots, short-term uptake of 65Zn-labeled phytosiderophores was compared in the Fe-efficient maize cultivar Alice and the maize mutant ys1 carrying a defect in Fe-phytosiderophore uptake. In ys1, uptake and translocation rates of Zn from Zn-phytosiderophores were one-half of those in Alice, but no genotypical difference was found in Zn uptake and translocation from other Zn-binding forms. In ys1 and in tendency also in Alice, Zn uptake decreased with increasing stability constant of the chelate in the order: ZnSO4 [greater than or equal to] Zn-desferrioxamine > Zn-phytosiderophores > Zn-EDTA. Adding a 500-fold excess of free phytosiderophores over Zn to the uptake solution depressed Zn uptake in ys1 almost completely. In uptake studies with double-labeled 65Zn-14C-phytosiderophores, ys1 absorbed the phytosiderophore at similar rates when supplied as a Zn-chelate or the free ligand. By contrast, in Alice 14C-phytosiderophore uptake from the Zn-chelate was 2.8-fold higher than from the free ligand, suggesting that Alice absorbed the complete Zn-phytosiderophore complex via the putative plasma membrane transporter for Fe-phytosiderophores. We propose two pathways for the uptake of Zn from Zn-phytosiderophores in grasses, one via the transport of the free Zn cation and the other via the uptake of nondissociated Zn-phytosiderophores.
223 citations
TL;DR: It is suggested that the expression of Zn efficiency mechanism is causally related to phytosiderophore-mediated enhanced mobilization of ZN from sparingly soluble Zn pools and from adsorption sites, both in the rhizosphere and plants.
Abstract: The effect of the zinc (Zn) nutritional status on the rate of phytosiderophore release was studied in nutrient solution over 20 days in four bread wheat (Triticum aestivum cvs. Kirac-66, Gerek-79, Aroona and Kirkpinar) and four durum wheat (Triticum durum cvs. BDMM-19, Kunduru-1149, Kiziltan-91 and Durati) genotypes differing in Zn efficiency.
160 citations
TL;DR: In this paper, during two convective storms, mass fluxes of wind-blown particles were measured in a pearl millet (Pennisetum glaucum) field in southwest Niger, on a sandy, siliceous, isohyperthermic Psammentic Paleustalf.
Abstract: This study was conducted to quantify nutrient losses by saltation and suspension transport. During two convective storms, mass fluxes of wind-blown particles were measured in a pearl millet (Pennisetum glaucum) field in southwest Niger, on a sandy, siliceous, isohyperthermic Psammentic Paleustalf. The trapped material at three heights (0·05, 0·26 and 0·50 m) and a sample of vertically deposited dust were analyzed for total element contents of K, C, N and P. The nutrient content of the material at 0·05 m was similar to the nutrient content of the topsoil. At 0·50 m, the material was three times richer in nutrients than the topsoil, whereas the deposited dust, trapped at 2·00 m, was 17 times richer. For all four elements, a total element (TE) mass flux profile was fitted throughout the observations. From the TE profiles, the following nutrient losses from the experimental plot were estimated: 57·1 kg ha−1 K, 79·6 kg ha−1 C, 18·3 kg ha−1 N, and 6·1 kg ha−1 P. The TE profiles showed a maximum value in the saltation layer. The suspended TE mass fluxes above the saltation layer were an order of magnitude lower than the saltation fluxes, but extended to greater heights. Therefore, saltation and suspension are both able to transport significant quantities of nutrients. While saltation results in only a local redistribution of nutrients, suspension may transport dust over thousands of kilometers, resulting in a regional loss of nutrients.
149 citations
TL;DR: It is concluded that a 5-day parenteral fish oil supplementation has an immunomodulatory effect on lipid-mediator generation in human leukocytes in postoperative trauma.
Abstract: The incorporation of omega-3 and omega-6 fatty acids (FAs) into leukocyte membranes and the leukotriene (LT)B4-, LTB5 -, LTC4-, and LTCs-synthesizing capacity in stimulated leukocytes were measured following parenteral omega-3 FA nutrition in 20 postoperative patients. Total parenteral nutrition (TPN) over 5 days postoperatively was isonitrogenous (0.24 g N x kg-1 x d1) and isoenergetic (92 kJ/22 kcal x kg-1 x d-1), containing 0.15 g fish oil and 0.85 g soybean oil per kg-1 x d-1 (FO) or 1.0 g soybean oil x kg-1 x d-1 (SO). Following 5 days' FO administration, the content of eicosapentaenoic acid (EPA) was increased 2.5-fold, LTB5 1.5-fold, and LTC5 sevenfold. With SO nutrition, EPA and LTB5 generation remained unaltered, whereas LTC5 doubled. The production of LTB4 and LTC4 was not affected in any of the groups. We conclude that a 5-day parenteral fish oil supplementation has an immunomodulatory effect on lipid-mediator generation in human leukocytes in postoperative trauma.
134 citations
TL;DR: In this article, the Ypr10*c gene was identified as a ribonuclease function for the common bean (Phaseolus vulgaris L) protein and was found to have significant sequence similarity to the ginseng protein.
Abstract: The intracellular pathogenesis-related (PR) proteins of common bean (Phaseolus vulgaris L.) are encoded by a highly polymorphic family of at least 20 genes. One member, the Ypr10*c gene, has been isolated and characterised. The deduced amino acid sequence of the encoded protein, PR-10, exhibits similarities to tree-pollen allergens, to food allergens from celery and apple and to ginseng ribonuclease peptide sequences. We show by RNA blot analysis that the Ypr10 gene family, including Ypr10*c, is strongly expressed in bean roots. In leaves Ypr10 transcript levels are low in young and mature stages but are elevated during senescence and in diseased states. Dark treatment of leaves causes strong induction of Ypr10 transcripts, which is reversible by light, and diurnal rhythms of transcript accumulation during the night are observed. Ypr10 genes are responsive to external stimuli related to pathogen-defence such as glutathione or salicylic acid. Transcriptional activity of a Ypr10*c promoter-beta-glucuronidase fusion gene in transgenic tobacco was observed in roots, in developing xylem and phloem of stems, and in the blade of senescent leaves, with highest levels at the onset of senescence. The most striking characteristic of developmental expression was the specific localisation of beta-glucuronidase activity in the transmitting tract of styles in flowers at anthesis. Feeding of various pathogen-related and stress-related stimuli to young tobacco leaves led to accumulation of GUS activity in leaf blades. We identify considerable spatio-temporal similarities between reported expression patterns of Ypr10 genes and ribonuclease genes, which, together with the significant sequence similarity to the ginseng ribonuclease, support the hypothesis of a ribonuclease function for PR-10 proteins and allow the prediction of possible biological roles.
134 citations
TL;DR: In this paper, the maturity of apple fruit at harvest was examined as a factor affecting later flavour development, and it was suggested that fundamental physiological processes such as respiration and ethylene production may be limiting factors for volatile production in earlier-harvested fruit.
130 citations
TL;DR: The results suggest that the enhanced capacity of genotypes for Zn uptake and translocation from roots to shoot meristems under deficient Zn supply might be the most important factor contributing to Zn efficiency in wheat genotypes.
Abstract: Six bread wheat (Triticum aestivum cvs. Kirac-66, Gerek-79, Aroona, ES 91-12, ES-14 and Kirkpinar) and four durum wheat (Triticum durum cvs. BDMM-19, Kunduru-1149, Kiziltan-91 and Durati) genotypes were grown under controlled environmental conditions in nutrient solution for 20 days to study the effect of varied supply of Zn (0 to 1 µM) on Zn deficiency symptoms in shoots, root and shoot dry matter production, and distribution of Zn in roots and shoots.
TL;DR: In this paper, the changes in acid and base in soil during growth of field beans (Vicia faba L. cv. Alfred) and after incorporation of the plant material into the soil were studied.
Abstract: During cultivation of legumes soil is acidified due to proton release from roots. As a consequence of proton release, plants accumulate organic anions which may, if returned and decomposed in the soil, neutralize the soil acids. Until now the detailed processes responsible for the change in soil pH after incorporation of plant material have not been completely understood. Using a pot experiment we studied the changes in acid and base in soil during growth of field beans (Vicia faba L. cv. Alfred) and after incorporation of the plant material into the soil. Soil pH was significantly decreased by field beans from 6.00 to 5.64 in a cultivation period of 45 days. Proton release amounted to 32.7 mmol H+ pot-1, which was approximately equivalent to the accumulated alkalinity in the plant shoots (34.4 mmol). Return of field bean shoots caused a significant soil pH increase from 5.64 to 6.29. Within 7 days more than 90% of the added alkalinity was released. After 307 days incubation, soil pH decreased to 5.86 due to nitrification. In a second experiment, maize leaves (Zea mays L.), containing various concentrations of nitrogen and at various alkalinities, were incorporated into the soil. Soil pH change was positively correlated to alkalinity and malate concentration and negatively correlated to total nitrogen and water-soluble organic nitrogen of incorporated leaves. It is concluded that the soil acidification caused by legume cultivation can be partly compensated for if crop residues are returned to the soil. Addition of plant material may initially cause an increase in soil pH due to decomposition of organic anions and organic nitrogen. Soil pH may decrease if nitrification is involved. The concentrations of nitrogen and alkalinity of added plant material are decisive factors controlling soil pH change after incorporation of plant material.
TL;DR: In this article, a multi-purpose solar tunnel dryer was used to dry bananas under the hot and humid weather conditions of Thailand in order to investigate its performance, and seven drying tests were conducted at the Royal Chitralada Projects in Bangkok during March-May 1995.
TL;DR: Prospects for improving 1SCB resistance by marker-assisted breeding are promising, based on data mapped and characterized quantitative trait loci affecting resistance to the leaf feeding generation of SCB, grain yield under both protection and infestation with SCB larvae, and plant height.
Abstract: Sugarcane borer (SCB), Diatraea saccharalis Fabricius, is a serious pest in tropical maize production areas in the Americas. Little is known about the genetic resistance of maize genotypes to this pest. In this study, we mapped and characterized quantitative trait loci (QTL) affecting resistance to the leaf feeding generation of SCB (1SCB), grain yield under both protection (GYP) and infestation (GYI) with SCB larvae, and plant height (PITT). A total of 171 F2 genotypes derived from cross CML131 (susceptible) × CML67 (resistant) 93 RFLP marker loci were used in QTL analyses. F3 lines were evaluated for the above traits and grain yield reduction (GYR) in field experiments with two replications at two or three tropical environments. Resistance was assessed by rating leaf feeding damage after artificial infestation with SCB larvae. The method of composite interval mapping with selected markers as cofactors was used for detection and characterization of QTL. Resistance to 1SCB was significantly affected by 10 putative QTL on Chromosomes 1, 2, 5, 7, 8, 9, and 10. These showed predominantly additive gene action and explained 65.0% of the phenotypic variance and 93.5% of the genetic variance in a simultaneous fit. Six QTL for GYP, five QTL for GYI with primarily dominant genetic effects, and four QTL for PHT with primarily additive genetic effects were identified, explaining in total about one third of the phenotypic variance for the respective trait. No more than one putative QTL was found to be common between different characters. QTL × environment interaction was found to be significant for 1SCB ratings only. Based on these data, prospects for improving 1SCB resistance by marker-assisted breeding are promising.
TL;DR: It is concluded that sunlight influences the beta-carotene and alpha-tocopherol content of blood and tissues.
Abstract: We conducted a randomized placebo-controlled double-blind study in 20 healthy young female students (skin type II + III, body mass index 18–22) in order to evaluate the efficacy of 10 weeks of mode
TL;DR: In this article, the effects of management practices on soil microbial properties and to relate those effects to changes in the microbially available part of the soil organic matter were measured in the plough layer of field plots from a haplic Luvisol at the ‘Ihinger Hof’ near Stuttgart, SW Germany.
Abstract: Adenosine triphosphate (ATP) contents, enzymatic activities, cellulose decomposition in situ, aggregate stability, total organic C contents, C- and N-mineralization potentials and amounts of water-soluble C compounds were measured in the plough layer of field plots from a haplic Luvisol at the ‘Ihinger Hof’ near Stuttgart, SW Germany Plots had been treated differently for 14 years with regard to tillage (ploughing, rotary cultivation) and crop rotations (legume-cereals, rape-cereals) Soils were sampled from the 0–10 cm and 10–25 cm layer of the Ap horizon 4 times in 1990 during and after the vegetative growth of oats On the basis of the input and distribution of crop and root residues during the previous 8 years a model for the decomposition of organic substances was used to estimate the amounts of the microbially-decomposable organic substances added to the plots (decomposable young soil organic matter, DYSOM) Our aim was to study the effects of management practices on soil microbial properties and to relate those effects to changes in the microbially-available part of the soil organic matter The contents of total soil organic C, total N, ATP, and soil microbial activities in the 0–10 cm layer were mostly higher with rotary cultivation than with ploughing In contrast, either no differences between the tillage systems or higher values with ploughing occurred in the second soil layer (10–25 cm) In the upper soil layer of the rape-cereals crop rotation soil microbial biomass was higher and more active than in the legume-cereals crop rotation In the lower soil layer no uniform effects of the crop rotations were found For the 0–10 cm layer there was an overlapping effect of cultivation and crop rotation on soil organic matter fractions and microbial biomass Differences in soil microbial measurements were partly related to differences in humus contents However, variations in microbial properties with different treatments were mostly larger than variations in total organic C content, sometimes occurring without any difference in total organic C contents In these cases the contents of DYSOM and soil pH were found to have a dominant influence Soil physical properties either showed only little differences (texture, bulk density), or were highly correlated to total organic C contents (water contents) There seemed to be a contradiction between a tendency for higher microbial activities and at the same time larger humus contents on plots with rotary cultivation compared to ploughing This may be explained by a higher C efficiency in these plots, ie the soil microbial biomass-to-organic C ratio was relatively high and accompanied by small changes in biomass contents during the year
TL;DR: In this paper, experimental results from their laboratory and literature data are used to describe the potential activity of tree roots and mycorrhizas in nutrient and water uptake in forest trees.
Abstract: Although per growing season nutrient uptake of adequately growing forest trees is less than the nutrient uptake of annual crop species, nutrient uptake per unit root length in trees is considerable. Because of high heterogeneity of soil conditions and root growth in forest soils, modelling of uptake processes is even more difficult for forest than for crop stands. Detailed studies show that white lips of growing tree roots have a high nutrient uptake capacity. However, most root tips are usually colonised by mycorrhizal fungi. These fungi can participate substantially in tree nutrient uptake, in particular in the utilisation of organically-bound phosphorus and nitrogen in soils. Mycorrhizal hyphae, root tips, and older root zones can all absorb water, but their actual contribution is difficult to assess. In this review, experimental results from our laboratory and literature data are used to describe the potential activity of tree roots and mycorrhizas in nutrient and water uptake. Methodology for in situ measurements must be developed to quantify at different forest sites the actual contribution of mycorrhizas and different root parts.
Nahrstoff- und Wasseraufnahme durch Wurzeln von Waldbaumen
Der jahrliche Nahrstoffbedarf gut wachsender Waldbestande ist geringer als der Nahrstoffbedarf von Kulturpflanzen, aber immer noch so erheblich, das Wurzeln von Waldbaumen eine hohe Nahrstoffaufnahme-kapazitat haben mussen. Die Nahrstoffkonzentrationen in der Bodenlosung sind im Wald ublicherweise geringer als auf Ackerland. Vor allem sind jedoch sowohl das Nahrstoffangebot als auch das Wurzelwachstum auf Waldstandorten grosen raumlichen und zeitlichen Schwankungen unterworfen. Die intensive Nahrstoff- und Wasseraufnahme durch nicht verbraunte, wachsende Wurzelspitzen von Waldbaumen ist experimentell gut untersucht. Die meisten Wurzelspitzen, insbesondere von Koniferenwurzeln, sind jedoch durch Ektomykorrhizapilze besiedelt. Anhand von eigenen Versuchsergebnissen und Literaturbeispielen wird im vorliegenden Artikel gezeigt, das die Pilze eine grose Rolle bei der Nahrstoffversorgung des Baumes ubernehmen konnen, insbesondere bei der Verwertung organischer Nahrstoffquellen.
TL;DR: In this paper, the effects of spacers on the local flow and mass transport phenomena in narrow rectangular ducts including different spacers were investigated in gas flows in a wind tunnel, and a fundamental study of the geometric parameters, based on the results of Schock [1], led to a new definition of the hydraulic diameter.
TL;DR: The non-haem chloroperoxidase gene (cpoF) from the pyrrolnitrin producer Pseudomonas fluorescens BL914 was cloned using an oligonucleotide derived from part of the N-terminal amino acid sequence of chloroperxidase (CPO-P) from PseUDomonas pyrrocina as a probe and partial characterization of the enzyme showed that it belongs to the class of bacterial non- Haem C
Abstract: The non-haem chloroperoxidase gene (cpoF) from the pyrrolnitrin producer Pseudomonas fluorescens BL914 was cloned using an oligonucleotide derived from part of the N-terminal amino acid sequence of chloroperoxidase (CPO-P) from Pseudomonas pyrrocina as a probe. Based on the overexpression of cpoF in Escherichia coli and the stabilty of CPO-F against higher temperatures and proteases, the enzyme was purified to homogeneity. Partial characterization of the enzyme showed that it belongs to the class of bacterial non-haem CPOs. To investigate the role of CPO-F in pyrrolnitrin biosynthesis, the cpoF gene was inactivated by insertion of a kanamycin cassette. Exchange of the chromosomal cpoF gene against the disrupted copy had no influence on pyrrolnitrin production demonstrating that CPO-F was not involved in pyrrolnitrin biosynthesis.
TL;DR: In plants grown without Zn, release of phytosiderophores progressively increased with the onset of visual Zn deficiency symptoms, such as inhibition of shoot elongation and appearance of chlorotic and necrotic patches on leaves.
Abstract: The effect of the zinc (Zn) nutritional status on the rate of phyto‐siderophore release was studied in three wild grass species (Hordeum murinum, Agropyron orientale, and Secale cereale) grown in nutrient solution under co‐trolled environmental conditions. These wild grasses are highly “Zn‐efficient”; and grow well on severely Zn‐deficient calcareous soils in Turkey (DTPA‐extractable Zn was 0.12 mg/kg soil and CaCO3 was 37%). In all wild grasses studied, Zn deficiency reduced shoot growth but had no effect on root growth. Low amounts of phytosiderophores were released from roots of all wild grasses adequately supplied with Zn. In plants grown without Zn, release of phytosiderophores progressively increased with the onset of visual Zn deficiency symptoms, such as inhibition of shoot elongation and appearance of chlorotic and necrotic patches on leaves. Compared to Zn‐sufficient plants, phytosiderophore release increased 18–20‐fold in deficient plants. HPLC analysis of root exudates showed that the...
TL;DR: In this paper, the suitability of the sensors has been examined in laboratory and field tests, and the technical equipment has been evaluated in both testbed and field field conditions, showing that the accuracy of yield mapping can be increased by additional measuring of grain moisture, actual cutting width and the dynamics of the grain transport within the combine.
TL;DR: In this article, the response of carbohydrate metabolism in 3-year-old Norway spruce plants to an increased amount of nitrogen supply to a N-poor forest soil was investigated in a pot experiment.
Abstract: The response of carbohydrate metabolism in 3-year-old Norway spruce plants to an increased amount of nitrogen supply to a N-poor forest soil was investigated in a pot experiment. After 7 months of treatment we found a decreased amount of starch in both needles and roots, together with decreased amounts of sucrose in needles of those plants grown under an enhanced inorganic N supply. In addition, the activity and the protein amount of the anaplerotic enzyme phosphoenolpyruvate carboxylase (PEPC) and the activity of NADP-dependent isocitrate dehydrogenase (IDH) were clearly increased. The activity of sucrose phosphate synthase (SPS) and the pool size of fructose 2,6-bisphosphate (F26BP) were not affected by high supply of inorganic N. These data indicate a shift of carbon flow from starch formation towards an enhanced provision of carbon skeletons for N assimilation and shoot growth. In parallel, we found decreased contents of fungus-specific compounds (ergosterol, mannitol, trehalose) in roots, which are indicators of a decreased colonization by ectomycorrhizal fungi, probably as a result of a changed allocation and partitioning of photoassimilates due to an increased N supply.
TL;DR: Quantitative trait loci involved in the resistance of maize to Setosphaeria turcica, the causal agent of northern leaf blight, were located by interval mapping analysis of 121 F2:3 lines derived from a cross between Mo17 (moderately resistant) and B52 (susceptible).
Abstract: Quantitative trait loci (QTL) involved in the resistance of maize to Setosphaeria turcica, the causal agent of northern leaf blight, were located by interval mapping analysis of 121 F2:3 lines derived from a cross between Mo17 (moderately resistant) and B52 (susceptible) A linkage map spanning 112 RFLP loci with 15 cM mean interval length was constructed, based on marker data recorded in a previous study Field tests with artificial inoculation were conducted at three sites in tropical mid- to high-altitude regions of Kenya, East Africa Host-plant response was measured in terms of incubation period, disease severity (five scoring dates), and the area under the disease progress curve (AUDPC) Heritability of all traits was high (around 075) QTL associated with the incubation period were located on chromosomes 2S and 8L For disease severity and AUDPC, significant QTL were detected in the putative centromeric region of chromosome 1 and on 2S, 3L, 5S, 6L, 7L, 8L and 9S On 2S the same marker interval which carried a gene enhancing latent period was also associated with reduced disease severity of juvenile plants QTL on chromosomes 3L, 5S, 7L and 8L were significant across environments but all other QTL were affected by a large genotype x environment interaction Partially dominant gene action for resistance as well as for susceptibility was prevailing Single QTL explained 10 to 38% of the phenotypic variation of the traits All but the QTL on chromosomes 1, 6 and 9 were contributed by the resistant parent Mo17 On chromosome 8L a QTL mapped to the same region as the major race-specific gene Ht2, supporting the hypothesis that some qualitative and quantitative resistance genes may be allelic
TL;DR: Electrophysiological studies on the insects' olfactory receptor organs reveal that certain cell types, which are not involved in perception of the attractive odorants, respond to deet and/or KBR 3023, suggesting that K BR 3023 may act via subsets of G-protein-coupled receptors in sensory neurones.
Abstract: Starting from a set of known repellent compounds, a general structural framework with high probability for repellent activity was developed by molecular modelling techniques. Synthesis, structure–biological activity relationships of acylated 1,3-aminopropanols on the yellow fever mosquito Aedes aegypti and the properties and activity of the new development candidate compound KBR 3023 on Ae. aegypti, the malaria mosquito Anopheles stephensi, the common house mosquito Culex quinquefasciatus and the stable fly Stomoxys calcitrans are described. The sensory effect of KBR 3023 and deet has been studied in behavioural and neurophysiological investigations on Ae. aegypti and the American cockroach Periplaneta americana.
The compounds clearly reduce or even eliminate the approach behaviour towards attractants like host odours or sexual pheromones. Electrophysiological studies on the insects' olfactory receptor organs reveal that certain cell types, which are not involved in perception of the attractive odorants, respond to deet and/or KBR 3023. As soon as one of the compounds is presented together with an attractant, a new input is active in the brain, which adds to the input from other receptors activated by the attractant. This new overall pattern clearly differs from that elicited by the attractant, so that the insect is no longer able to detect the latter.
The specificity and mode of action of KBR 3023 was investigated by experiments exploring second-messenger responses elicited in antennal preparations of male P. americana. KBR 3023 induced a rapid increase in the concentration of inositol triphosphate in a dose-dependent and tissue-specific manner; other second-messenger systems were not affected. These observations suggest that KBR 3023 may act via subsets of G-protein-coupled receptors in sensory neurones.
TL;DR: Fenvalerate, diflubenzuron and Bt prevented the development of the larvae once eggs had hatched, but 50% of the eggs developed as far as the larval and pupal stages and larvae caused damage to the tubes.
TL;DR: It was concluded that increased root respiration was mainly responsible for the growth reduction in mycorrhizal compared with non-mycorrhIZal plants, whereas the production of fungal biomass in the extramatrical mycelium of mycor rhizal plants was of minor importance.
Abstract: summary
In seedlings of Norway spruce (Picea abies (L.) Karst.), grown in semi-hydroponic sand culture, mycorrhizal infection decreased growth (Eltrop & Marschner, 1996). Possible reasons for this growth depression were investigated in the present study by comparing the plant and fungal biomass distribution and carbon partitioning between non-mycorrhizal and mycorrhizal (Pisolitlius tinctorius) plants supplied with ammonium or nitrate as source of N.
Despite the high mycorrhizal infection rate (55–71% of total root tips), the amount of fungal biomass in roots and extramatrical mycelium of mycorrhizal plants accounted for less than 3% of plant dry matter and was significantly lower in nitrate- than in ammonium-supplied plants.
The CO2 assimilation rates were higher in mycorrhizal than in non-mycorrhizal plants supplied with ammonium as well as those supplied with nitrate. High light intensity considerably increased CO2 assimilation rates. The respiration rates of the intact root systems were significantly increased in ammonium-supplied mycorrhizal plants compared with non-mycorrhizal plants. The amount of CO2 lost in root respiration as a percentage of the amount of CO2 gained in photosynthesis (respiratory quotient), ranged from 49.3% at 30°C root zone temperature and low light intensity (290 μmol m−2 S−1) to 11.7% at 10 °C and high light intensity (990 μmol m−2 s−1). In ammonium-supplied plants grown at 22 °C and low light intensity, the proportion of carbon lost by root respiration was significantly higher in mycorrhizal than in non-mycorrhizal plants. This increase in root respiration was of the same order of magnitude (7.4 %) as the decrease in dry matter production by mycorrhizal plants (10.1 %). In nitrate-supplied plants, no significant difference in the respiratory quotient was found between non-mycorrhizal and mycorrhizal plants. The respiration rate per unit d. wt of the fungal mycelium was estimated to account for 31.3 % (ammonium supply) and 8.3 % (nitrate supply) of that of the total mycorrhizal root system although the dry weight accounted for only 4. % (ammonium supply) and 2.5 % (nitrate supply). Accordingly, the respiration rate was calculated to be 11.1 times higher with ammonium supply, and 3.4 times higher with nitrate supply, than that of the root tissue. The carbohydrate concentrations in shoots and roots were not consistently different between non-mycorrhizal and mycorrhizal plants.
It was concluded that increased root respiration was mainly responsible for the growth reduction in mycorrhizal compared with non-mycorrhizal plants, whereas the production of fungal biomass in the extramatrical mycelium of mycorrhizal plants was of minor importance.
TL;DR: The chitinase of A. viteae infective stage larvae (L3) is identified as the main target of the humoral immune response of jirds, which were protected against challenge infection after vaccination with irradiation attenuated L3.
TL;DR: In this article, the effects of drying air temperature up to 100°C and position of halved dehusked coconuts with respect to the direction of the air stream were investigated at constant air velocity of 0.5 m s−1 and tropical dew point temperature of 25°C so that good quality copra and coconut oil were produced at the shortest drying time.
TL;DR: The tannins from quebracho and leaves of Acioa barteri after purification, and commercially available tannic acid, were stored in buffers of different pH values (6−11) at 0, 20, and 37 °C as mentioned in this paper.
Abstract: The tannins from quebracho and leaves of Acioa barteri after purification, and commercially available tannic acid, were stored in buffers of different pH values (6−11) at 0, 20, and 37 °C. The recovery of tannins was monitored at different time intervals (up to 18 h) using Folin−Ciocalteu and butanol−HCl−Fe3+ reagents. The recovery of tannins decreased with increase in time of storage, increase in pH, and increase in temperature. The decrease in the recovery of tannins was accompanied by a decrease in their protein precipitation capacity, and also there was no defined peak for the assay medium following the butanol−HCl−Fe3+ method for the purified quebracho and A. barteri tannins when stored at pH 11. These observations suggested that the decrease in recovery of tannins was due to inactivation of tannins. A. barteri tannins were found to be most susceptible to pH-mediated inactivation. The stirring of quebracho tannins increased the rate of inactivation at pH 11. The results suggested that alkaline pH ina...
TL;DR: It is demonstrated that purified aphrodisin, a hamster mounting pheromone, modulates IP3 production in male VNO membranes without altering cAMP production and establishes the importance of IP3 cascades in mammalian reproductive behavior.
Abstract: COMPOUNDS present in estrous hamster vaginal discharge modulate male attraction and mounting behavior. These compounds are differentially processed by chemosensory neurons in the main olfactory epithelium (MOE) and vomeronasal organ (VNO). The transduction cascade responsible for this processing is unclear in the VNO, although studies of the MOE suggest that the second messengers cAMP or IP 3 may be involved. Here we demonstrate that purified aphrodisin, a hamster mounting pheromone, modulates IP 3 production in male VNO membranes without altering cAMP production. Aphrodisin does not alter the concentration of either second messenger in membranes from the MOE. These results confirm the specificity of the VNO in the processing of mounting pheromones and establishes the importance of IP 3 cascades in mammalian reproductive behavior.