Landscape-ecological mapping of the Netherlands

The Landscape-ecological Mapping of the Netherlands project (LMN project) started in 1983 with the aim of establishing a landscape-ecological database for use in developing and evaluating national land-use plans. The project, working with grid cells of 1 km², has four working objectives: a) development of mapping potential for basic landscape-ecological data, b) assessment of susceptibility to interventions, c) evaluation of significance for nature conservation and d) production of vulnerability maps, as a combination of susceptibility and significance. In addition to information on soil, groundwater, ecotopes, flora and fauna, the database also incorporates information on physiographical features and entire landscapes. The resulting database is a geographic information system (GIS). This article describes the second phase of the project (1985–1989), covering the Randstad area, and focusses on the methods and the applications potential of the database.     

Effects of predator hunting mode on grassland ecosystem function

The way predators control their prey populations is determined by the interplay between predator hunting mode and prey antipredator behavior. It is uncertain, however, how the effects of such interplay control ecosystem function. A 3-year experiment in grassland mesocosms revealed that actively hunting spiders reduced plant species diversity and enhanced aboveground net primary production and nitrogen mineralization rate, whereas sit-and-wait ambush spiders had opposite effects. These effects arise from the different responses to the two different predators by their grasshopper prey-the dominant herbivore species that controls plant species composition and accordingly ecosystem functioning. Predator hunting mode is thus a key functional trait that can help to explain variation in the nature of top-down control of ecosystems.     

Relationships between sulfur concentration in mulberry Leaves and the quality of silkworm cocoon

A 40-day gnotobiotic microcosm experiment was carried out to quantify the effect of bacterial-feeding nematode on plat growth and nutrient absorption.The results showed that inoculation of bacterial-feeding nematode Protorhabditis sp.stimulated the growth of wheat (Triticum aestivum) and the uptake of N.By the end of the 40-day incubation wheat biomass and N uptake in the treatment with nematode and bacteria (Pseudomonas sp.)increased by 6.5% and 5.9%,respectively,compared with bacteria alone treatment.The presence of nematode mainly accelerated the growth of aboveground of wheat,while it slightly inhibited the root development.There was little difference in plant tissue N concentration between treatments.P concentration and uptake of wheat,however,were generally reduced by nematode, It appears that the enhancement of plant growth and nitrogen uptake is attributed to the enhancement of nitrogen mineraliztion induced by nematode feeding on bacteria,and the reduction of phosphorous uptake is the result of ewak root status and comptetition by bacteria immobilzation.     

Identification of volatile compounds in cantaloupe at various developmental stages using solid phase microextraction

Using an automated rapid headspace solid phase microextraction (SPME) method for volatile extraction in cantaloupes, 86 compounds already reported for muskmelons were recovered and an additional 53 compounds not previously reported were identified or tentatively identified. The SPME method extracted a copious number of volatiles that can be analyzed to clearly differentiate between variety, growth stage, and stage of harvest ripeness. Most of the newly reported compounds in cantaloupe were esters and aldehydes that have already been demonstrated as flavor-related compounds in other products. All esters believed to have flavor impact increased progressively after pollination, and this trend continued with increasing harvest maturity. However, compound recovery often decreased when fruits were harvested over-ripe. Most aldehydes increased during early growth stages and then tapered off with increasing harvest maturity. The SPME method suitably recovered most compounds reported to impart characteristic flavor/aroma in muskmelons. SPME offers experimental flexibility and the ability to discover more compounds and address flavor quality changes in fresh-cut cantaloupe.     

Mungbean [Vigna radiata (L.) Wilczek] globulins: purification and characterization

Vicilin type (8S) and basic 7S globulins and legumin type (11S) globulins were isolated from mungbean [Vigna radiata (L.) Wilczek]. The native molecular weights of the different globulin types were 360000 for legumin, 200000 for vicilin, and 135000 for basic 7S. Some of the 8S globulin apparently complexed and coeluted with the 11S on gel filtration. On SDS-PAGE, 11S was composed of two bands of 40000 and 24000, 8S was composed of 60000, 48000, 32000, and 26000 bands, and basic 7S was composed of 28000 and 16000 bands. The percent composition of total globulins was estimated to be as follow: 8S, 89%; basic 7S, 3.4%; and 11S, 7.6%. The basic 7S and 11S but not the 8S globulins were found to have disulfide bonds. The presence of carbohydrates by conjugated peroxidase reaction was observed in all bands of 8S, the acidic polypeptide of basic 7S, and its complex but not in 11S. The 28000 basic 7S band and its 42000 complex and the first three major bands of 8S cross-reacted with antibodies to all types of soybean conglycinin subunits (alpha, alpha', and beta), whereas the fourth band cross-reacted only with the anti-beta subunit. None of the mungbean globulins cross-reacted with anti-soybean glycinin. Basic 7S was found to be easily extracted with 0.15 M NaCl, 11S was extracted with 0.35 M NaCl,and 8S was extracted over a wide range of NaCl concentrations. The N-terminal sequences of the different subunits/fragments of the globulins were determined and found to have strong homology with storage proteins of other legumes and crops.     

Regioselective dimerization of ferulic acid in a micellar solution.

Dehydrodimers of hydroxycinnamates play an important role in the cross-linking of plant cell walls. An aqueous solution of quaternary ammonium salts with a long aliphatic chain is known to spontaneously organize itself into micelles with the ionic part at the outer sphere. It is shown that regioisomeric ferulic acid dehydrodimers can be obtained in one step from trans-ferulic acid after attachment to these micelles and using the biomimetic peroxidase-H2O2 system. The surfactant hexadecyltrimethylammonium hydroxide yielded trans-4-(4-hydroxy-3-methoxybenzylidene)-2-(4-hydroxy-3-methoxyphenyl)-5-oxotetrahydrofuran-3-carboxylic acid (25%), (E,E)-4,4'-dihydroxy-5,5'-dimethoxy-3,3'-bicinnamic acid (21%), and trans-5-[(E)-2-carboxyvinyl]-2-(4-hydroxy-3-methoxyphenyl)-7-methoxy-2,3-dihydrobenzofuran-3-carboxylic acid (14%), whereas the surfactant tetradecyltrimethylammonium bromide gave 4-cis, 8-cis-bis(4-hydroxy-3-methoxyphenyl)-3,7-dioxabicyclo[3.3.0]octane-2,6-dione (18%) as the main product. The use of micelles appears to be not only a new way to synthesize regioisomeric ferulic acid dehydrodimers but may also help to understand the regiospecificity of dimeric hydroxycinnamate formation in vivo.     

New device for direct extraction of volatiles in solid samples using SPME.

A new device that allows extraction of volatiles from solid materials by SPME, avoiding preparation of the sample, was designed and tested in two different food products. Volatiles from dry-cured ham and canned liver sausage were analyzed by headspace SPME (HS SPME) and by using a new device that protects the SPME fiber in the core of the solid material. Volatile profiles generated by using both methods of extraction were very similar in both products. Compounds that have been previously highlighted as quality markers, such as products from oxidative degradation of lipids, products from Strecker degradation of amino acids, or terpenes, were satisfactorily extracted by SPME coupled to the device for direct extraction. In addition, by using this method no laboratory contaminants were extracted, whereas some major laboratory solvents were presented in the chromatogram using the HS SPME method. However, coefficients of variation were higher when performing the direct sampling procedure. This new device appears to have potential as a simple method for extracting volatiles in solid materials while at the same time avoiding taking samples.     

Kiwellin, a modular protein from green and gold kiwi fruits: evidence of in vivo and in vitro processing and IgE binding

Kiwellin, an allergenic protein formerly isolated from green kiwi fruit, has been identified as the most abundant component of the gold kiwi species. A protein named KiTH, showing a 20 kDa band on reducing SDS-PAGE and 100% identity with the C-terminal region of kiwellin, has been identified in the extract of the ripe green species. In vitro treatment of purified kiwellin with the protease actinidin from green kiwi fruit originated KiTH and kissper, a recently described pore-forming peptide. Primary structure analysis and experimental evidence suggest that kiwellin is a modular protein with two domains. It may undergo in vivo proteolytic processing by actinidin, thus producing KiTH and kissper. When probed with sera recognizing kiwellin from green kiwi fruit, KiTH showed IgE binding, with reactivity levels sometimes different from those of kiwellin. The IgE-binding capacity of kiwellin from gold kiwi fruit appears to be similar to that of the green species.     

Development of an appropriate procedure for estimation of RUSLE EI30 index and preparation of erosivity maps for Pulau Penang in Peninsular Malaysia

Pluviographic data at 15 min interval from 6 stations in Pulau Penang of Peninsular Malaysia were used to compute rainfall erosivity factor (R) for the revised universal soil loss equation (RUSLE). Three different modelling procedures were applied for the estimation of monthly rainfall erosivity (EI₃₀) values. While storm rainfall (P) and duration (D) data were used in the first approach, the second approach used monthly rainfall for days with rainfall ≥ 10 mm (rain₁₀) and monthly number of days with rainfall ≥ 10 (days₁₀). The third approach however used the Fournier index as the independent variable. Based on the root mean squared error (RMSE) and the percentage error (PE) criteria, models developed using the Fournier index approach was adjudged the best with an average PE value of 0.92 and an average RMSE value of 164.6. Further, this approach was extended to the development of a regional model. Using data from additional sixteen stations and the Fournier index based regional model, EI₃₀ values were computed for each month. ArcView GIS was used to generate monthly maps of EI₃₀ values and also annual rainfall erosivity (R). The rainfall erosivity factor (R) in the region was estimated to vary from 9000 to 14,000 MJ mm ha^− 1 h^− 1 year^− 1.