Comparison of the developmental patterns of mitochondrial malate dehydrogenase between mung bean and cucumber cotyledons during and following germination

The development of mitochondrial NAD⁺-malate dehydrogenase (EC 1.1.1.37) in mung bean and cucumber cotyledons was followed. using the antibody raised against it, during and following germination. The developmental patterns were quite different between the two. In cucumber, the content of mitochondrial malate dehydrogenase continued to increase through 3–4 days after the beginning of imbibition. This was, at least in part, due to active synthesis of the enzyme protein, and the synthesis seemed to be regulated by the availability of the translatable mRNA for the enzyme. In mung bean, on the other hand, the enzyme was present in dry cotyledons at a rather high concentration, and remained at a constant level between day 1 and day 3 after the reduction of the content to one-half its initial level during the first day. De novo synthesis of the enzyme could not be detected in mung bean cotyledons by pulse-labeling experiment.     

Ectomycorrhizal colonization on black spruce and jack pine seedlings outplanted in reforestation sites

Six-week-old, mycorrhiza-free, bareroot jack pine and black spruce seedlings were outplanted in ten reforestation sites, situated between 45–48° latitude N and 69–74° longitude W, within the province of Quebec, representing diverse operational forestry disturbances and ecological conditions. Two months after outplanting, root systems of black spruce seedlings had fewer mycorrhizae than those of jack pine seedlings. Ectomycorrhizal colonization on black spruce seedlings did not vary significantly with the reforestation site. Percent mycorrhizal colonization for these seedlings was positively correlated with seedling dry weight while with the jack pine seedlings, mycorrhizal colonization varied significantly with the outplanting site and there was no correlation between mycorrhizal formation and seedling dry weight. Multiple linear regressions showed pH to be a determinant soil factor for mycorrhizal colonization for the two species. Drainage was the other influential factor affecting colonization of black spruce while organic matter accumulation was more important for jack pine. Inoculation with selected ectomycorrhizal fungi could be more important for black spruce than for jack pine seedlings.     

Isozyme gene markers in Vicia faba L.

Summary This study was conducted to assess the genetic basis of the variability observed for the glutamate oxaloacetate transaminase (GOT), Superoxide dismutase (SOD), esterase (EST), and malate dehydrogenase (MDH) isozyme systems in different open-pollinated Vicia faba varieties. Individual plants showing contrasting zymogram patterns were simultaneously selfed and cross-combined. Crossing was unsuccessful in producing progeny, and only selfed progenies were suitable for genetical analysis of isozyme variability. Three zones of GOT activity were made visible. The isozyme of GOT-2 and GOT-3 zones were dimeric and under the control of three alleles at the Got-2 locus and two alleles at the Got-3 locus, respectively. The isozymes of the GOT-1 zone did not show any variability. Three zones of SOD isozyme activity were made visible. The isozymes occurring in the SOD-1 (chloroplastic isozyme form) and SOD-2 (cytosol isozyme form) zones were dimeric and under the control of two alleles at the Sod-1 and Sod-2 loci. The isozyme visualized in the SOD-3 zone (mitochondrial isozyme form) were tetrameric and under the control of two alleles at the Sod-3 locus. Apparently the isozymes made visible in the most anodal esterase zones EST-1, EST-2, and EST-3 were monomeric, and the occurrence of two alleles at each of two different loci explained the variability observed in the EST-2 and EST-3 zones. For MDH, only two five-banded zymogram pattern types were found, and every selfed progeny showed only one of the two zymogram type, indicating that each individual possessed fixed alleles at the loci controlling MDH isozyme. Got-2, Got-3, Sod-1, Sod-2, and Sod-3 appear to be five new isozyme gene markers that can be useful in Vicia faba breeding for linkage study, varietal fingerprinting, outcrossing rate estimate, and indirect selection for quantitative characters.     

DNA structures associated with autonomously replicating sequences from plants

DNA fragments capable of conferring autonomous replicating ability to plasmids inSaccharomyces cerevisiae were isolated from four different plant genomes and from the Ti plasmid ofAgrobacterium tumefaciens. The DNA structure of these autonomously replicating sequences (ARSs) as well as two from yeast were studied using retardation during polyacrylamide gel electrophoresis and computer analysis as measures of sequence-dependent DNA structures. Bent DNA was found to be associated with the ARS elements. An 11 bp ARS consensus sequence required for ARS function was also identified in the elements examined and was flanked by unusually straight structures which were rich in A+T content. These results show that the ARS elements from genomes of higher plants have structural and sequence features in common with ARS elements from yeast and higher animals.Supported by Grant 1RO1-GM41708-O1 from the National Institute of Health.     

Performance of nymphal and adult Nezara viridula on selected alternate host plants

Laboratory studies with the southern green stink bug, Nezara viridula (L.) (Hemiptera: Pentatomidae), feeding on seeds or fruits of some alternate host plants, demonstrated differences in nymphal survival and development time, and body weight at adult emergence. Lowest mortalities (25%) were observed for nymphs on fruits of dakota mustard [Brassica kaber (DC.)] and siberian motherwort (Leonurus sibiricus L.). On fruits of castor bean (Ricinus communis L.) nymph mortality was ca. 60%, and on mature seeds of L. sibiricus ca. 75%. Total development time from second instar to adult ranged from ca. 26 days on B. kaber to ca. 42 days on R. communis. Fresh body weight at adult emergence was greatest for nymphs on L. sibiricus and lowest on R. communis. Adult survival after 30 days and mean longevity was greater on L. sibiricus than on the remaining foods, being drastically reduced on R. communis. In general, reproductive performance on all foods was similar, except R. communis, on which no female reproduced. Female weight gain of N. viridula was generally greater on L. sibiricus On R. communis, adults lost weight during their first week and showed the lowest weight gain at the end of day 29. Field observations coupled with these laboratory studies suggest that in the Warta area (northern Paraná state, Brazil, 23° 11 S), L. sibiricus and B. kaber are important alternate food plants in the seasonal phenology of N. viridula. R. communis, however, is of poor nutritional quality, serving primarily as a refuge.

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Résumé L'alimentation au laboratoire de N. viridula avec les graines et les fruits de diverses plantes a entraîné différentes mortalités larvaires, différentes vitesses de développement et des différences dans les poids des adultes à l'émergence. Les mortalités les plus faibles (25%) on été observées avec les fruits de Brassica kaber DC. et de Leonurus sibiricus L.Avec les fruits de Ricinus communis L., la mortalité larvaire était de 60%; sur graines mûres de L. sibiricus, elle était de 75%. La durée du développement du second stade à l'adulte a varié de 26 jours sur B. kaber à 42 jours sur R. communis. Le poids frais des adultes à l'émergence était le plus élevé avec L. sibiricus et le plus faible avec de R. communis. La longévité des adultes au-delà de 30 jours était la plus élevée avec L. sibiricus, et était fortement réduite avec R. communis. Dans l'ensemble, la reproduction était de même importance avec les différents aliments, à l'exception de R. communis avec lequel les femelles ne se reproduisaient pas. Le gain de poids des femelles était généralement supérieur avec L. sibiricus; avec R. communis les adultes ont perdu du poids pendant la première semaine et ont présenté le plus faible gain à la fin du 29ème jour.Des observations dans la nature, associées à ces expériences de laboratoire, laissent supposer que dans la zone de Warta (au Nord de l'état de Paraná, 23° 11 S, au Bresil), L. sibiricus et B. kaber sont des plantes hôtes alternatives importantes dans la phénologie saisonnière de N. viridula. Cependant, R. communis, de faible valeur alimentaire, sert avant tout de refuge.

     

Non-everted oxygenated rat intestinal segments as a measure of neutral detergent fiber effects on iron absorption

Iron absorption in the presence of varying amounts and sizes of dietary fiber was measured. A method using non-everted rat intestinal segments perfused in oxygen was refined. Neutral detergent fiber (NDF), a component of dietary fiber, was extracted from cooked pinto bean (Phaseolus vulgaris). The NDF did not affect iron absorption in intestinal segments from iron replete rats. However, 4 and 6 mg of NDF/ml significantly decreased iron absorption in the intestinal segments from anemic rats. NDF with a smaller particle size of 0.125 mm increased iron absorption relative to that absorbed with 0.180 mm particles. Histological examination validated using non-everted intestinal segments perfused with oxygen as a method for studying dietary effects on iron absorption. Segments which are not everted are less prone to damage. Perfusion with oxygen maintained metabolic activity in the tissue during the experiment.     

Comparative analysis of the lipopolysaccharides of a rough and a smooth strain of Pseudomonas syringae pv. phaseolicola

The lipopolysaccharides (LPS) of a rough (R) and a smooth (S) strain of Pseudomonas syringae pv. phaseolicola were analysed. The S-LPS revealed markedly more rhamnose and fucose, but less glucose, than the R-LPS. The presence of 3-O-methyl-rhamnose (acofriose) in the S-LPS was confirmed by cochromatography with authentic acofriose. SDS polyacrylamide gel electrophoresis of the S-LPS demonstrated a cluster of regularly spaced high molecular weight fractions, which was almost lacking in the R-LPS. The main fatty acids of the lipid A of both LPS species were 3-OH-10:0,3-OH-12:0,2-OH-12:0, and 12:0. Two N-linked diesters were demonstrated: 3-O(12:0)-12:0 and 3-O(2-OH-12:0)-12:0. S-LPS was subjected to mild hydrolysis and the degraded polysaccharide separated into three fractions by gel permeation chromatography on a Fractogel TSK HW-50 column. Fraction I, representing nearly only the O-specific side chain, consisted of rhamnose and fucose in a molar ratio of 4:1, with 4% of the rhamnose being 3-O-methylated (acofriose). Fraction II, representing mostly core material, was composed of glucose, rhamnose, heptose, glucosamine, galactosamine, alanine, and a still unidentified amino compound, in an approximate molar ratio of 3:1:1:1:1:1:1, and KDO. Fraction III consisted of released monomers and salts. The LPS was highly phosphorylated (3.28% phosphorus in the core fraction). The thus characterized composition of the LPS O-chain seems to be unique for the pathovar phaseolicola of P. syringae, although many similarities exist to other pathovars as well as to other bacterial species.Abbreviations LPS lipopolysacchairdes - GC/MS combined gas liquid chromatography-mass spectrometry - HVE high voltage electrophoresis - KDO 2-keto-3-deoxyoctonic acid - PAGE polyacrylamide gel electrophoresis - SDS sodium dodecylsulfate P.s. pv. phaseolicola is termed P. phaseolicola in the text     

Analysing partitioning of recently fixed and of reserve carbon in reproductive Phaseolus vulgaris L. plants

Abstract. Partitioning of recently-fixed carbon among plant organs and subsequent distribution of reserve carbon were studied by supplying whole shoots of bean plants ( Phaseolus vulgaris L.) with ¹⁴C-labelled CO₂ of constant specific radioactivity throughout a photoperiod. The gain of tracer carbon in each part revealed net accumulation of recently-fixed carbon from direct fixation, import or both. Growth rate coefficients describing the present pattern of plant growth were calculated from ratios of tracer carbon to total carbon present in plant organs and were used to project future plant form. The period 10–20 d after the start of flowering was marked by a major increase in partitioning of recently-fixed carbon to reproductive growth. Growth rates for the plant and its parts during this period were projected on the basis of growth rate coefficients and were found to be similar to rates measured by gravimetric growth analysis. Changes in tracer carbon recovered in individual organs after chase periods of various lengths revealed net decreases for leaves and stems. About 9% of the carbon distributed to fruits came from reserves even in the absence of obvious stress. Respiratory loss during the chase period was determined from the progressive drop in recovery of the original tracer carbon. The methods are being applied to measure current net accumulation rates in studies of sink organ physiology, and to compare partitioning of recently-fixed and of stored carbon in several plant species under defined growth conditions.     

Chromium in plants

Chromium is an essential trace element and is associated with some biological pathways, especially with glucose tolerance. For these reasons, we decided to determine the concentration of chromium in two sets of Brazilian medicinal plants. The first group consisted of plants that are considered as antidiabetic, whereas the second included plants that do not have this therapeutic property. The concentration of chromium was determined by flameless atomic absorption. All the plants analyzed contain chromium in the normal range for this element, but the hypoglycemic plants contain more chromium than the others (1–4 μg/g compared to 0.5–1.5 μg/g).