Isocitrate Lyase from Germinating Soybean Cotyledons: Purification and Characterization

Ruchti, M. and Widmer, F. 1986. Isocitrate lyase from germinatingsoybean cotyledons: purification and characterization.—J.exp. Bot. 37: 1685–1690. Isocitrate lyase (E.C. 4.1.3.1 [EC] ) was purified from the cotyledonsof 7-d-old soybean seedlings. Three molecular forms were detectedwith pi values of 6·46, 6·25 and 6·0. Themain form (pl = 6·46) had an approximate Mr of 130000,a pH optimum of 8·0, a K_m (isocitrate) close to 2·0mol m^–3 and a molecular activity of 615 min ^–1 at25 °C. The purified enzyme is not a glycoprotein and isheat labile. Key words: Isocitrate lyase, soybean     

Effects of Increasing Water Stress on Simulated Swards of Festuca arundinacea Schreb under Wind Tunnel Conditions

The effects of increasing water stress on water relations, leafconductance, leaf extension and leaf rolling of Festuca arundinaceain sward (I m²) were investigated under wind tunnel conditions.The plants were grown in a container 60 cm deep and the experimentwas conducted over a 36 d period. Upon cessation of watering(day 11), leaf extension and conductance were affected. Within8 d, the onset of leaf rolling helped to reduce transpirationand to maintain leaf water potential. Nocturnal recovery of turgor potential helped in maintainingleaf extension at a moderate level and in the final 5 d waterand osmotic potentials dropped sharply as leaf rolling becamemore acute and leaf extension stopped. The grass combines various morphological and physiological mechanismsto prevent water losses and maintain growth. Festuca arundinacea, tall fescue, wind tunnel, water stress, water potential, osmotic potential, conductance, leaf rolling, leaf extension     

Organisation spatiale des fibres de collagène de la plaque basale des écailles des Téléostéens

Spatial organization of collagenous fibrils in the basal plate of elasmoid scales has been studied in 36 species among 24 teleost families which include the whole order. Angle measurements of the various fibrillary directions were performed on fracture surfaces in frozen scales observed with the scanning electron microscope. The organization of the basal plate is arrayed in three basic patterns. The most remarkable one, found in the more "primitive" families, is a double twisted plywood with a left-handed rotation of the fibrillary directions. The remaining two are an orthogonal plywood, more or less regular, and an "intermediate" plywood, both found among the more "advanced" families. However, an orthogonal plywood is also observed in some "primitive" families, for example in Clupeidae and Salmonidae. We tentatively interpret the left-handed double twisted plywood of the lower teleosteans and of Amiidae as a synapomorphy in relation to the primitive condition of an actinopterygian lineage. On the other hand, within the teleosts, we would consider that the double twisted plywood is a plesiomorphic condition and that the orthogonal plywood is an apomorphy among the "advanced" teleosts families.     

Morphometric stepwise discriminant analysis of the five genetically determined European taxa of the genus Mus

Univariate and multivariate analyses have been performed on skull and mandible measurements for the five biochemically defined groups of the genus Mus in Europe. Four of these taxa occur in Bulgaria; other samples came from France and Israel. This extensive biometrical analysis has allowed us to establish diagnostic keys for these taxa.     

DNA sequence variation of the mitochondrial control region among geographically and morphologically remote European brown trout Saltno trutta populations

Throughout its natural range, the brown trout Salmo trutta L. exhibits a complex pattern of morphological and life-history variation. This has led to considerable taxonomic confusion, hampering the understanding of the evolutionary history of the species. To document the phylogenetic relationships among morphologically and geographically remote brown trout populations across western Europe, we determined the DNA sequence variation in segments of the mitochondrial control region for 151 individuals representing 24 populations. DNA was prepared for double-stranded sequencing by the polymerase chain reaction (PCR). Twenty-one variable nucleotide positions within a 640-bp fragment surveyed defined 12 genotypes differing by a mean of 7 nucleotide substitutions (range 1-12). Five major phylogenetic assemblages differing by mean sequence divergence estimates of 0.96 to 1.44% were identified. These groupings exhibited a strong spatial partitioning but lacked congruence with either ecological or morphological differentiation. Complete mitochondrial DNA (mtDNA) monomorphism across all Atlantic basin populations contrasted with the high interdrainage genetic diversity observed in more southerly populations. This study exemplified the usefulness of mitochondrial DNA sequence analysis for estimating phylogenetic relationships within S. trutta populations.     

Grass Leaf Elongation Rate as a Function of Developmental Stage and Temperature: Morphological Analysis and Modelling

Elongation of successive leaves was measured following defoliationof tall fescue plants in controlled environments. Measurementswere made under constant temperatures of 24 °C and 14 °C,and after temperature changes from 24 to 14 °C andvice versa.A morphological analysis of the growing leaf was made from thetime it was 1 mm long until it was fully elongated. The timeelapsed from initiation until the leaf was 1 mm long was estimated.Young leaves less than 1.5 mm long elongated slowly at a constantleaf elongation rate (LER). By extrapolating this LER back toleaf initiation from the apex it was calculated that elongationlasted 42.5 d at 24 °C and 51 d at 14 °C. Lengths ofthe division zone (DZ) and the extension-only zone (E-OZ) increasedto a maximum and then decreased during leaf development. Temperaturechange had an immediate effect on LER but the response varieddepending on the direction of the temperature change. To describethese different features, an empirical model of DZ and E-OZwas designed. Its five parameters were optimized at constanttemperature. The model was then used to simulate the LER ofplants subjected to temperature changes. Instant and lastingeffects of the initial temperature on mean LER in plants transferredfrom 14 to 24 °C andvice versawere well simulated. It wasconcluded that the major reason for differences was due to thegrowth stage (DZ and E-OZ lengths) at which the changes occurredat both temperatures.Copyright 1999 Annals of Botany Company Festuca arundinaceaSchreb., tall fescue, growth zone, division zone.     

Electron Microprobe Analysis of Zinc Incorporation into Rumen Protozoa

SYNOPSIS. With the aid of electron microprobe analysis on ciliate spreads, we detected zinc in ciliates and its accumulation in the endoplasm. A correlation was found between the amount of zinc accumulation and its concentration in the medium. By the same microprobe analysis of ultrathin sections, we determined semiquantitatively the zinc accumulation in the intracytoplasmic granules and its presence in macronuclei and in intra- and extracellular bacteria.     

Cd uptake by intact wheat plants

Abstract. An investigation of the uptake of Cd by intact wheat plants has been carried out. The accumulation of Cd in the roots as a function of time and external Cd concentration was determined. Since the transport of Cd to the grains and shoots was found to be small, only uptake into the root was examined further. An appreciable fraction of the Cd absorbed by the roots can be desorbed and consequently constitutes the freely diffusible and exchangeable fraction.
The effect of temperature and of metabolic inhibitors on the absorption provides evidence that another Cd fraction is taken up by metabolically mediated processes. The absorption of this Cd fraction was found to be inhibited by Cu and Zn. The inhibitory effect of Cu and Zn on Cd absorption was comparable.     

Monoclonal Antibodies Identify a Subset of Dense Granules in Cryptosporidium parvum Zoites and Gamonts

ABSTRACT. Two monoclonal antibodies raised against purified oocysts and excysted sporozoites of Cryptosporidium parvum identified antigens located in the anterior half of sporozoites by indirect immunofluorescence microscopic assay. The monoclonal antibodies also reacted with Triton X-100-insoluble antigens of asexual and sexual stage parasites developing in epithelial cells in vitro and identified a 110 kilodalton antigen on immunoblots of sodium dodecyl sulfate-extracted oocysts. Immunoblotting reactivity was abolished by prior treatment of blotted antigen with periodic acid suggesting that the monoclonal antibodies recognize a carbohydrate or carbohydrate-dependent epitope(s). By immunoelectron microscopy, the antibodies reacted with a family of small, electron-dense granules located predominantly in the central region of merozoites and also with a population of cytoplasmic inclusions in macrogamonts. In addition, the monoclonal antibodies prominently labeled the parasitophorous vacuole membrane of all intracellular stages examined suggesting that the corresponding antigen(s) may be exocytosed from the granules to become associated with Triton X-100-insoluble components of the vacuolar membrane or cytoskeleton.