Ries De Visser

IsoLife B.V.

Plant biomass conversion by saprotrophic fungi plays a pivotal role in terrestrial carbon (C) cycling. The general consensus is that fungi metabolize carbohydrates, while lignin is only degraded and mineralized to CO 2 . Recent research, however, demonstrated fungal conversion of ¹³ C-monoaromatic compounds into proteinogenic amino acids. To unambi...

With the ever-advancing lignocellulose valorization strategies, lignin analyses need to advance as well. However, lignin quantification still heavily relies on unspecific, time- and sample consuming gravimetric and spectrophotometric analyses. Here, we demonstrate that lignin isolates from uniformly ¹³C labeled wheat straw, willow and douglas fir,...

Understanding mechanisms underlying plant biomass recalcitrance at molecular level can only be achieved by accurate analyses of both content and structural features of the molecules involved. Current quantification of lignin is, however, majorly based on unspecific gravimetric analysis after sulphuric acid hydrolysis. Hence, our research aimed at s...

A relatively recent technique termed Comprehensive Multiphase (CMP) NMR spectroscopy was used to study the growth and associated metabolomic changes of 13C-labeled wheat seeds and germinated seedlings. CMP-NMR enables the study of all phases in intact samples: liquid, gel-like, semi-solid and solid, by combining all required electronics into a sing...

The origin of agricultural products is gaining in appreciation while often hard to determine for various reasons. Geographical origin may be resolved using a combination of chemical and physical analytical technologies. In the present case of Lily of the Valley (Convallaria majalis) rhizomes, we investigated an exploratory set of material from The...

Seeds are complex entities comprised of liquids, gels and solids. NMR spectroscopy is a powerful tool for studying molecular structure, but has evolved into two fields, solution- and solid-state. Comprehensive Multi-phase (CMP)-NMR spectroscopy is capable of liquid, gel, and solid-state experiments for studying intact samples where all organic comp...

a b s t r a c t The isothiocyanate sulforaphane, present in significant amounts in broccoli (Brassica oleracea L.) seedlings in the form of its precursor glucoraphanin, has been identified as an inducer of quinine reductase, a phase-II detoxification enzyme known for its anticarcinogenic properties. Its concentration in broccoli seedlings usually d...

New stable isotope enriched plant compounds for use as internal standards Ries de Visser1, Arno Hazekamp2 & Ton Gorissen1, 1IsoLife, Bornsesteeg 65 6708 PD Wageningen, The Netherlands; 2Prisna, P.O.Box 506, 3233 ZK Oostvoorne, The Netherlands. Plant metabolome analysis by mass spectrometry can be improved by stable isotope labelled internal stand...

* The results of a single publication stating that terrestrial plants emit methane has sparked a discussion in several scientific journals, but an independent test has not yet been performed. * Here it is shown, with the use of the stable isotope (13)C and a laser-based measuring technique, that there is no evidence for substantial aerobic methane...

The influence of shoot transpiration on the rates of growth and nitrogen fixation was investigated in Pisum sativum L. cv. Rondo. In short term experiments, rates of transpiration and acetylene reduction of intact plants were measured simultaneously, using air-tight perspex vessels enclosing the basal part of the nodulated root. In long term experi...

This book consists of edited and revised versions of the 20 invited papers presented at an International Symposium on Grassland Ecophysiology and Grazing Ecology held at Curitiba, Parana, Brazil on 24-26 August 1999. The papers are on the sustainability of grazing systems (1); environmental constraints and plant responses to defoliation (4); morpho...

The quantitative significance of reserves and current assimilates in regrowing tillers of severely defoliated plants of perennial ryegrass (Lolium perenne L.) was assessed by a new approach, comprising 13C/12C and 15N/14N steady-state labeling and separation of sink and source zones. The functionally distinct zones showed large differences in the k...

Little is known about interactions between seeds within the inflorescence of perennial ryegrass ( Lolium perenne L.) and their effect on final seed weight. These relations were investigated in two glasshouse experiments using two genotypes, by reducing the number of seeds in an inflorescence at anthesis. In the first experiment, entire spikelets we...

The contribution of pre-defoliation reserves and current assimilates to leaf and root growth was examined in Lolium perenne L. during regrowth after defoliation. Differential steady-state labelling with 13C (CO2 with δ13C = –0·0281 and –0·0088) and 15N (NO3– with 1·0 and 0·368 atom percentage, i.e. δ15N = 1·742 and 0·0052, respectively) was applied...

The present study explores the potential contribution of the energy requirements associated with nocturnal carbohydrate export to (1) the fraction of dark respiration correlating with leaf nitrogen concentration and (2) the dark respiration of mature source leaves. To this end, we determined the nocturnal carbohydrate-export rates from leaves with...

Protein turnover is generally regarded as a major maintenance process, but experimental evidence to support this contention is scarce. Here we quantify the component of dark respiration rate associated with overall protein turnover of tissues in vivo. The effect of an inhibitor of cytosolic protein synthesis (cycloheximide, CHM) on dark respiration...

Maintenance of ion gradients across plant membranes is considered to be an important process requiring respiratory energy in plant tissues. In order to test this hypothesis, roots of intact plants of potato (Solanum tuberosum L. cv. Alcmaria and cv. Pimpernel) were incubated in a closed circulation system. Electrical conductivity of the solution su...

The rate of dry matter accumulation by seeds of Vicia faba L. cv. Minica increases with temperature in the range of 16 to 26 degrees C. The duration of dry matter accumulation decreases with temperature, resulting in a decrease of final seed dry weight. In this study we test the hypothesis that a diffusion barrier for O(2), located in the seed coat...

Using an open air flow system, differences in the yellowing rate of leaves during curing were assessed in relation to ethylene production by shoots of intact seedlings or attached mature leaves of 60 day old tobacco (Nicotiana tabacum L.) plants. The rate of ethylene evolution from the leaves of the fast yellowing cultivars was significantly higher...

The aim of this brief review is to discuss some intriguing new developments which should receive more attention, and to indicate some areas where rapid progress could be made if biochemists, physiologists and biophysists would join forces. The subject of plant growth and respiration has been extensively reviewed during the last few years, including...

Changes in the efficiency of root respiration were examined on intact plants of Pisum sativum L. cv Rondo after addition of nitrate or ammonium to the culture solutions. Nitrate was absorbed immediately after addition and elicited a respiratory rise (O(2)-uptake as well as CO(2)-production) to 160% at most. This occurred both in roots of plants fix...

The function of alternative path respiration in roots was investigated in pea plants (Pisum sativum L. cv. Rondo). Plants were grown in symbiosis with Rhizobium leguminosarum (strain PF2), completely dependent on N2 fixation, or non-nodulated, receiving nitrate or ammonium at the same rate as N2 was fixed in symbiosis. Under these conditions, relat...

Plants of Urtica dioica L., a very nitrophilous species, were grown in a nutrient solution containing either high (100%) or low (2%) nutrient supply. Part of these plants were subjected to a sudden switch from 100% to 2% or vice versa. Plant weight, sugar and organic nitrogen (both soluble and insoluble) and nitrate content were measured during gro...

The control of electron flow through the cytochrome and alternative pathways was studied in intact roots of Plantago lanceolata L., P. major L. ssp. major and Pisum sativum L. cv. Rondo, grown either on nitrate or on ammonium. Root respiration in these species was highly resistant to 0.2 mM cyanide and sensitive to 25 mM salicylhydroxamate (SHAM)....

The contribution of the alternative pathway in root respiration of Pisum sativum L. cv Rondo, Plantago lanceolata L., and Plantago major L. ssp major was determined by titration with salicylhydroxamate (SHAM) in the absence and presence of cyanide. SHAM completely inhibited the cyanide-resistant component of root respiration at 5 to 10 millimolar w...

This paper discusses some aspects of the energy metabolism in nodulated roots. It is the aim to address the problem if the supply of photosynthates to the nodulated roots or the production of metabolic energy in respiratory pathways limits the rate of N2-fixation in nodulated roots of vegetative Pisum sativum plants. Our approach involves the deter...

The control of the relative efficiency (RE) of N2 fixation in legume root nodules has been the subject of many investigations and hypotheses (Davis et al.1975, Bethlenfalvay, Phillips 1977, Edie 1983, Hageman, Burris 1980). We report on the RE of pea root nodule nitrogenase activity as affected by energy supply and mean age of the bacteroids.

Growth and efficiency of root respiration were investigated in Pisum sativum L. cv. Alaska and cv. Rondo. Plants were grown in culture solutions, either in symbiosis with Rhizobium leguminosanm, or with an abundant supply of nitrate or ammonium and completely lacking nodules. In comparison with plants utilizing nitrate or ammonium, Ni-fixing plants...