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  • Gas chromatography  (280)
  • Triticum aestivum  (263)
  • Electron microscopy  (252)
  • Springer  (795)
  • American Meteorological Society
  • 2005-2009
  • 1985-1989  (422)
  • 1980-1984  (373)
  • 1925-1929
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 261 (1983), S. 373-374 
    ISSN: 1435-1536
    Keywords: Electron microscopy ; short-time staining ; nodular structure ; crystallization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 2
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    Colloid & polymer science 263 (1985), S. 116-119 
    ISSN: 1435-1536
    Keywords: Electron microscopy ; staining ; morphology ; nylon-12 ; orientation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The morphology of drawn and annealed sheets of nylon-12 was investigated by transmission electron microscopy of stained sections, and the results compared with equivalent small-angle X-ray scattering (SAXS) patterns. A three-component structure was observed, consisting of crystalline (C) and amorphous (A) regions in the microfibrils and an interfibrillar component whose density was deduced to be intermediate between that of the C and A regions. The crystallite width was given satisfactorily by a Guinier analysis of the SAXS profile.
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  • 3
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    Colloid & polymer science 260 (1982), S. 564-569 
    ISSN: 1435-1536
    Keywords: lin. Polyethylene ; Single crystals ; Heat of Fusion ; DSC ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Recently published results for solution crystallized PE single crystals have shown, that the experimental heat of fusionΔH * is higher, if the solvent is exchanged to silicon oil (oil suspension samples) as compared with dried mats. This has been interpreted by the collapse of the original hollow pyramids during drying, inducing lateral defects within the lamellae. The present investigation does not confirm this unexpected result.ΔH * of dried mats (T c 66 to 91 °C) and of the corresponding oil suspension samples agree within the rather small limits of experimental error. The crystallinities as derived fromΔH *, density or WAXS are in excellent agreement. SEM micrographs of cold fractured dried mats show their spongy macromorphology, but TEM micrographs of stained ultra-thin sections reveal the lamellar morphology of the walls, consisting of curved lamellae and stacked hollow pyramides. If a dried mat is sintered at room temperature, a dense transparent film is obtained with a rather regular stacked morphology of large flat lamellae.ΔH * of these films agrees with that of the original mat.
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  • 4
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    Springer
    Entomologia experimentalis et applicata 34 (1983), S. 20-26 
    ISSN: 1570-7458
    Keywords: Dioryctria abietella ; Cone pyralid ; Lepidoptera ; Pyralidae ; Sex pheromone, (Z,E)-9,11-tetradecadienyl acetate ; Single sensillum recordings ; Electroantennography ; Gas chromatography ; Mass spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé L'analyse en chromatographie gazeuse associée à une détection électroantennographique a montré que l'acétate (Z,E)-9,11-tétradécadiényle (Z,E)-9,11–14:Ac est l'un des composants de la phéromone de Dioryctria abietella Schiff (Lepid.: Pyralidae). Couplage chromatographie en phase gazeuse spectrometrie de masse a montré la présence d'acétate tétradécadiényle avec un spectre de masse et un indice de rétention identiques au Z,E-9,11–14:Ac Un récepteur cellulaire sensible à la fois au Z,E-9,11–14:Ac et à un extrait de la femelle a été identifié sous l'antenne du mâle. Les analyses des antennogrammes et de la cellule isolée ont étayé la caractérisation du composant de la phéromone comme étant Z,E-9,11–14:Ac. Un récepteur cellulaire additionnel sensible à l'acétate (Z.)-9-tétradécadiényle et à l'acétate (Z.E.)-9,12-tétradécadiényle a été trouvé sur l'antenne du mâle, mais il n'était pas activé par l'extrait de la femelle. Sur le terrain Z,E-9,11–14:Ac, présenté seul, attirait des nombres importants de mâles de D. abietella. L'addition de l'acétate (Z)-9-tétradécényle a inhibé l'attraction des mâles par les pièges.
    Notes: Summary Gas chromatographic analyses coupled with electro-antennographic detection indicated that (Z,E)-9,11-tetradecadienyl acetate (Z,E-9, 11–14:Ac) is a pheromone component of the cone pyralid Dioryctria abietella. Gas chromatographic-mass spectrometric analyses confirmed the presence of a tetradecadienyl acetate with mass spectrum and retention index identical to Z,E-9,11–14:Ac. A receptor cell sensitive to both Z,E-9,11–14:Ac and the female extract was identified on the male antenna. An additional receptor cell sensitive to (Z)-9-tetradecenyl acetate and (Z,E)-9,12-tetradecadienyl acetate was found on the male antenna but was not activated by the female extract. In the field Z,E-9,11–14:Ac presented alone attracted significant numbers of male D. abietella. Addition of (Z)-9-tetradecenyl acetate inhibited the attraction of males to traps.
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  • 5
    ISSN: 1432-0789
    Keywords: Wheat ; Paddy straw compost ; N and P enrichment ; Rock phosphate ; Pyrite ; Triticum aestivum ; Nutrient uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A nutrient-rich compost from paddy straw was prepared using urea and Mussoorie rock phosphate for N and P enrichment respectively. Inorganic N was partly conserved in the compost by the addition of pyrite. Citric-acid-soluble P also increased with the addition of pyrite. Compost containing about 1.6% total N and 3.3% total P was found to be a good source of P for a wheat crop and also supplied a significant amount of N to the plants.
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  • 6
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    Biology and fertility of soils 3 (1987), S. 199-204 
    ISSN: 1432-0789
    Keywords: Phosphatases ; Rhizosphere ; Organic phosphorus ; Allium cepa ; Brassica oleracea ; Triticum aestivum ; Trifolium alexandrinum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The distribution of phosphatase activity and of phosphate fractions of the soil in the proximity of roots was studied in order to evaluate the significance of phosphatases in P nutrition of various plants (Brassica oleracea, Allium cepa, Triticum aestivum, Trifolium alexandrinum). A considerable increase in both acid and alkaline phosphatase activity in all the four soil-root interfaces was observed. Maximum distances from the root surface at which activity increases were observed ranged from 2.0 mm to 3.1 mm for acid phosphatase and from 1.2 mm to 1.6 mm for alkaline phosphatase. The increase in phosphatase activity depended upon plant age, plant species and soil type. A significant correlation was noticed between the depletion of organic P and phosphatase activity in the rhizosphere soil of wheat (r = 0.99**) and clover (r = 0.97**). The maximum organic P depletion was 65% in clover and 86% in wheat, which was observed within a distance from the root of 0.8 mm in clover and 1.5 mm in wheat. Both the phosphatases in combination appear to be responsible for the depletion of organic P.
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  • 7
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    Biology and fertility of soils 5 (1987), S. 76-82 
    ISSN: 1432-0789
    Keywords: Biomass accumulation ; Decomposition ; Litter ; Soil organic matter ; Soil respiration ; 14C deposition ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In a field experiment with 14C-labeled winter wheat conducted in the north-central region of the United States, crop-accumulated carbon (grain excluded) returned to the soil was found to be 542 g m−2 year−1. Almost half of the carbon from the underground compartment was released in the form of CO2 during the first 3 months after harvest due to very favorable conditions for biological activity. After 18 months, no less than 80% of the carbon from the plant residues was mineralized. About 16% of straw carbon and 24% of root carbon was transferred into soil organic matter. The annual rate of soil organic matter decomposition was approximated as 1.7%.
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  • 8
    ISSN: 1432-0789
    Keywords: Triticum aestivum ; T. turgidum ; Nitrogen fixation ; Field inoculation ; Acetylene reduction assay (ARA)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Eight commercial Israeli spring wheat cultivars (six Triticum aestivum and two T. turgidum) grown with 40 and 120 kg N/ha were tested for responses to inoculation with Azospirillum brasilense. At the low level of N fertilization (40 kg/ha), five cultivars showed significant increases in plant dry weight measured at the milky ripe stage; however, by maturation only the cultivar “Miriam” showed a significant increase in grain yield. Two cultivars, which had shown a positive inoculation effect at the earlier stages, had a significant decrease in grain yield. No significant effect of inoculation was found at the high N level. To confirm those results, four wheat (T. aestivum) cultivars were tested separately over 4 years in 4 different locations under varying N levels. Only Miriam showed a consistently positive effect of Azospirillum inoculation on grain yield. Inoculation increased the number of roots per plant on Miriam compared with uninoculated plants. This effect was found at all N levels. Nutrient (N, P and K) accumulation and number of fertile tillers per unit area were also enhanced by Azospirillum, but these parameters were greatly affected by the level of applied N. It is suggested that the positive response of the spring wheat cultivar “Miriam” to Azospirillum inoculation is due to its capacity to escape water stresses at the end of the growth season.
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  • 9
    ISSN: 1432-0789
    Keywords: Azospirillum brasilense ; Triticum aestivum ; Inoculation ; N and dry matter yield ; N percentages in plant parts ; Associative N2 fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Wheat plants (Triticum aestivum) grown in pots and in the field under the Mediterranean climate of the south of France were inoculated with a strain of Azospirillum brasilense. Comparisons with non-inoculated plants grown under the same conditions showed significant responses to inoculation with an increase in the number of fertile tillers, shoot and root dry weight, and root to shoot biomass ratio. The roots of inoculated plants attracted relatively more assimilates than those of the control plants until a late stage of growth (heading stage) but the rhizosphere respiration expressed per unit of root growth was not increased by inoculation. Nitrogen yield, both total and in grains, was also enhanced; however, N percentages of all aerial parts of the plants grown in pots were always statistically lower after inoculation than in the control. At maturity, the N % in seeds was 1.81 and 2.45, respectively. The possible mechanisms of this effect of inoculation under the experimental conditions of this study are discussed.
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  • 10
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    Biology and fertility of soils 7 (1988), S. 67-70 
    ISSN: 1432-0789
    Keywords: Root activity ; Soil C mineralization ; 14C-labelled plant material ; Decomposition stages ; Wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two different soils were amended with 14C-labelled plant material and incubated under controlled laboratory conditions for 2 years. Half the samples were cropped with wheat (Triticum aestivum) 10 times in succession. At flowering, the wheat was harvested and the roots removed from the soil, and a new crop was started. Thus, the soil was continuously occupied by predominantly active root systems. The remaining samples were maintained without plants under the same conditions. The aim of the experiment was to study the effects of active roots on C-mineralization rates during different stages of decomposition and during long-term incubation. During the first 200 days, corresponding to the active decomposition stages, the roots weakly reduced 14C mineralization. With a lower level of decomposition, when more than 60% of the initial 14C was mineralized and when the available nutrients were markedly exhausted by plant uptake, the roots stimulated 14C mineralization.[/ p]
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  • 11
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    Biology and fertility of soils 7 (1988), S. 71-78 
    ISSN: 1432-0789
    Keywords: Root activity ; Rhizosphere ; C metabolism ; Microbial biomass ; Microbial activity ; Wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two different soils were amended with 14C-labelled plant material and incubated under controlled laboratory conditions for 2 years. Half the samples were cropped with wheat (Triticum aestivum) 10 times in succession. At flowering, the wheat was harvested and the old roots removed from the soil, so that the soil was continuously occupied by predominantly active root systems. The remaining samples were maintained without plants under the same conditions. During the initial stages of high microbial activity, due to decomposition of the labile compounds, the size of the total microbial biomass was comparable for both treatments, and the metabolic quotient (qCO2-C = mg CO2-C·mg−1 Biomass C·h−1) was increased by the plants. During the subsequent low-activity decomposition stages, after the labile compounds had been progressively mineralized, the biomass was multiplied by a factor of 2–4 in the presence of plants compared to the bare soils. Nevertheless, qCO2-C tended to reach similar low values with both treatments. The 14C-labelled biomass was reduced by the presence of roots and qCO2-14C was increased. The significance of these results obtained from a model experiment is discussed in terms of (1) the variation in the substrate originating from the roots and controlled by the plant physiology, (2) nutrient availability for plants and microorganisms, (3) soil biotic capacities and (4) increased microbial turnover rates induced by the roots.
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  • 12
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    Biology and fertility of soils 4 (1987), S. 37-40 
    ISSN: 1432-0789
    Keywords: Azospirillum brasilense ; Azospirillum amazonense ; rate reductase ; Inoculation ; Wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Three field experiments with wheat were conducted in 1983, 1984, and 1985 in Terra Roxa soil in Paraná, the major Brazilian wheat-growing region, to study inoculation effects of various strains of Azospirillum brasilense and A. amazonense. In all three experiments inoculation with A. brasilense Sp 245 isolated from surface-sterilized wheat roots in Paraná produced the highest plant dry weights and highest N% in plant tops and grain. Grain yield increases with this strain were up to 31 % but were not significant. The application of 60 or 100 kg N ha−1 to the controls increased N accumulation and produced yields less than inoculation with this strain. Another A. brasilense strain from surface-sterilized wheat roots (Sp 107st) also produced increased N assimilation at the lower N fertilizer level but reduced dry weights at the high N level, while strain Sp 7 + Cd reduced dry weights and N% in the straw at both N levels. The A. amazonense strain isolated from washed roots and a nitrate reductase negative mutant of strain Sp 245 were ineffective. Strains Sp 245 and Sp 107st showed the best establishment within roots while strain Cd established only in the soil.
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  • 13
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    Biology and fertility of soils 4 (1987), S. 41-46 
    ISSN: 1432-0789
    Keywords: Competition ; Migration ; Colonization potential ; Replica printing ; Triticum aestivum ; Pseudomonas fluorescens ; Bacillus subtilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Colonization patterns of Pseudomonas fluorescens and Bacillus subtilis on roots of wheat seedlings growing on water agar were studied qualitatively by replica printing and quantitatively by the plate count method. The results indicated a stronger colonization potential for P. fluorescens (up to 107 cfu/cm root) than for B. subtilis (up to 105 cfu/cm root). Although the numbers of both species were lower when inoculated together, the observed colonization patterns on the roots were comparable to those found with single inoculations. For none of these bacteria was active migration along the root surface in any direction observed, indicating that distal positions are reached mainly by a passive displacement on the root tip and elongating cells. Ecological implications of the observed phenomena are discussed.
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  • 14
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    Biology and fertility of soils 5 (1987), S. 31-35 
    ISSN: 1432-0789
    Keywords: Gaeumannomyces graminis ; VegVetative growth ; Pathogenicity ; Herbicides ; Diquat+paraquat ; Glyphosate ; Dicamba ; Trifluralin ; Chlorsulfuron ; Chlorthal dimethyl ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effects of Spray Seed (diquat + paraquat), Roundup (glyphosate), Banvel-D (dicamba), Treflan (trifluralin), Glean (chlorsulfuron) and Dacthal (chlorthal dimethyl) at concentrations of 0–500 ppm product on the vegetative growth, vigour and pathogenicity of Gaeumannomyces graminis var. tritici (Ggt) on wheat were examined. All herbicides with the exception of dicamba and chlorsulfuron inhibited fungal growth on potato dextrose agar (PDA) at concentrations 10–500-fold of rates recommended for use in the field. The vegetative growth of the pathogen growing out of straw colonized on PDA supplemented with 100 ppm diquat + paraquat or glyphosate was reduced by 47.4% and 42.4%, respectively. When portions of these colonies were subcultured onto unamended PDA, their growth and the pathogenicity of straw pieces colonized by these subcultures were found to be unaltered. Straw colonized by Ggt on agar amended with concentrations of diquat + paraquat or at all concentrations of glyphosate produced less root disease in wheat seedlings in comparison to those colonized on unamended agar. It is proposed that the reduced pathogenicity of inocula prepared on agar amended with these two herbicides is due to poor colonization by the pathogen of straw on these media, and that a similar effect on saprophytic colonization in the field could lead to a reduction in the field inocula of the pathogen.
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  • 15
    ISSN: 1432-0789
    Keywords: Biopores ; Root growth ; Transpiration ; Simulations ; Mechanical impedance ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The use of vertical biopores by wheat (Triticum aestivum) seminal roots for easy access to the subsoil and the consequences for plant water supply and yield has been investigated by computer simulation. Parameters included were: biopore density and diameter, depth of cultivation and strength of the subsoil — all under a wide range of seasonal weather conditions. The model predicts that biopores add significantly to root penetration at depth, even at a density of 0.1% v/v of small, vertical pores, while 1.5% to 2.0% v/v can ensure maximum root penetration. When the growing season is shorter a larger number of biopores is needed to ensure timely root penetration to depth. With shallow tillage, biopores occur closer to the soil surface, and their importance is increased. Deeper root penetration invariably gives greater water uptake and transpiration, but may have a negative effect on grain yield, especially under the driest climatic conditions. An increase in early water use may result in less soil water being available during the grain-filling period. The effect of biopores on plant transpiration varies from year to year, depending on the amount of rain and its distribution in time, and on the amount of soil water stored at time of sowing.
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  • 16
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    Current genetics 14 (1988), S. 163-170 
    ISSN: 1432-0983
    Keywords: Plant mtDNA ; Electron microscopy ; Restriction enzymes ; Hairpin structures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Broad bean (Vicia faba) mitochondrial DNA (mtDNA) includes three circular plasmids: mt-plasmid 1 (1,704 ntp), mt-plasmid 2 (1,695 ntp) and mt-plasmid 3 (1,476 ntp). Partially replicated circular forms of these mt-plasmids have been observed in electron microscope preparations. Restriction enzymes that cleave either mt-plasmid 2 (but not mt-plasmids 1 and 3) or mt-plasmid 3 (but not mt-plasmids 1 and 2) were used to generate linear forms of partially replicated mt-plasmid 2 and mt-plasmid 3 molecules. Analyses of these linearized replicative intermediates, observed by electron microscopy, indicated that in both mt-plasmid 2 and mt-plasmid 3 replication originates at a specific location and proceeds in the same, single direction around the molecules. The replication origins of mt-plasmid 2 and mt-plasmid 3 map close to sequences that can fold into hairpin structures.
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  • 17
    ISSN: 1432-0983
    Keywords: Sugar beet ; Cytoplasmic male sterility ; Mitochondrial DNA ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mitochondrial (mt) DNAs from normal (N) and male sterile (S) cytoplasms of sugar been have been isolated and investigated by electron microscopy. The results showed that mtDNA was composed of a heterogeneous population of circular molecules. Their contour lengths varied from 0.28 to 51 μm, but unlike in the case of maize, a large difference was not observed in the distribution of molecular classes greater than 1.0 μm between N and S cytoplasms of sugar beet. On the other hand, N and S cytoplasms were shown to contain their own characteristic combinations of small circular mtDNA species with lengths between 0.28 μm and 0.6 μm. Mitochondrial DNAs from various sources of male-sterile cytoplasms were analyzed by agarose gel electrophoresis to determine the extent of cytoplasmic variation. Additional low molecular weight DNA bands appeared in all male-sterile lines examined, and as a result, three distinctive banding patterns were recognized. These data are in general agreement with those based upon restriction endonuclease digestion of mt and chloroplast DNAs and the genetic analysis of fertility restoration in test crosses.
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  • 18
    ISSN: 1432-0983
    Keywords: Triticum aestivum ; Plant mitochondrial DNA ; Ribosomal genes ; Sequence rearrangements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nucleotide sequence of the wheat mitochondrial 26S ribosomal RNA gene and flanking regions was determined and compared with mitochondrial 26S rRNA genes from maize and Oenothera. All three genes exhibit a high degree of homology except within two variable regions. When the plant mitochondrial 26S rRNA genes are compared with Escherichia coli 23S rRNA and chloroplast 23S and 4.5S rRNA genes, a third variable region is apparent close to the 3′ end of the gene. The 5′ and 3′ ends of the wheat mitochondrial gene were determined by S1 nuclease mapping. Computer analysis of the wheat mitochondrial gene revealed several small sequences present either in the 5′ region of the 26S rRNA gene or in the 18S rRNA gene.
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  • 19
    ISSN: 1432-0983
    Keywords: Triticum aestivum ; Genomic variability ; Mitochondrial DNA ; Somatic tissue culture ; Regeneration ability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Embryogenic and non-embryogenic long-term callus cultures of hexaploid wheat exhibit differences in the organization of their mitochondrial genome. Embryogenic and non-embryogenic fractions of callus cultures initiated from immature embryos of the wheat cultivar “Chinese Spring” have been isolated and subsequently subcultured. DNA-DNA hybridization experiments using labelled cloned wheat mitochondrial DNA fragments have shown that the mitochondrial DNA organization of embryogenic subcultures derived from embryogenic parts of “Chinese Spring” calli is closely related to that of the initial “Chinese Spring” calli, while non-embryogenic subcultures derived from non-embryogenic fragments of “Chinese Spring” calli exhibit a mitochondrial DNA organization similar to that found in non-embryogenic calli derived from cultivar “Aquila”. In addition, somatic tissue cultures initiated from three other non-embryogenic wheat cultivars (“Talent”, “Thésée” and “Capitole”) display mitochondrial DNA arrangements similar to those found in cultivar “Aquila”. These results strongly suggest that, in wheat callus cultures, a particular mitochondrial genome organization is correlated with the ability of cultured cells to regenerate whole plants.
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  • 20
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    Journal of molecular evolution 26 (1987), S. 347-357 
    ISSN: 1432-1432
    Keywords: Ribosome structure ; Electron microscopy ; Image analysis ; Evolutionary lineages
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Multivariate statistical analysis and classification techniques are powerful tools in sorting noisy electron micrographs of single particles according to their principal features, enabling one to form average images with an enhanced signal-to-noise ratio and a better reproducible resolution. We apply this methodology here to determining the characteristic views of the large (50S) ribosomal subunits from the eubacteriumEscherichia coli and the archaebacteriaMethanococcus vannielii, Sulfolobus solfataricus, andHalobacterium marismortui. Average images were obtained of the subunit in the common crown and kidney projections, but views of the particle in orientations intermediate between these two extremes were also elucidated for all species. These averages show reproducible detail of up to 2.0 nm resolution, thus enabling the visualization and interspecies comparison of many structural features as a first step toward comparing the actual three-dimensional structures. Our results disprove evolutionary lineages recently postulated on the basis of electron microscopical images of ribosomal subunits.
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  • 21
    ISSN: 1432-1432
    Keywords: Primordial terrestrial atmospheres ; CH4, C2H2, CO2 ; Prebiotic synthesis ; High-frequency discharge ; Hydrocarbons ; Gas chromatography ; Mass Spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Various hydrocarbons were synthesized by high-frequency discharge in a primordial terrestrial model atmosphere. The products were extracted by benzene or methanol and analyzed by GC-MS. The mean carbon chain length of the hydrocarbons formed by the discharge through pure CH4 gas was less than 6. Benzene was also obtained. Some isomers were obtained for each of the hydrocarbons containing a given number of carbons. When a small amount of C2H2 was added to the CH4, longer chain compounds were formed, as compared with discharge in CH4 only. However, when the amount of C2H2 was increased, unextractable high molecular weight compounds were produced. The amounts of products decreased as the mixing ratio of CO2 to CH4 increased. No hydrocarbons were detected when the ratio of CO2/CH4 exceeded 1.
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  • 22
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    Trees 1 (1987), S. 94-101 
    ISSN: 1432-2285
    Keywords: Monoterpenes ; Abies alba Mill ; Resin ; Seeds ; Gas chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Using gas-chromatographic methods, the variability of the contents of monoterpene hydrocarbons (α-pinene, β-pinene, Δ3carene and limonene) in the resin of silver fir seeds (Abies alba Mill.) was studied. Resin cavities were characterized according to their position on the seed surface. It was estabilished that the terpene content of the resin of cavities localized on the abaxialadaxial surfaces of the seed differs significantly, creating a gradient of resin composition around the circumference of the seed. The differences between various resin cavities of single seeds were greater than the differences between different seeds of a single cone and between seeds of various cones on a single tree. An accurate definition of the resin cavity location on the seeds appears to be a fundamental condition for the collection of a sample representing the resin composition of individual trees. Resin biosynthesis in the course of organogenesis and the control of terpene contents in the resin of various locations on the seed and the cone are discussed.
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  • 23
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    Nutrient cycling in agroecosystems 20 (1989), S. 59-66 
    ISSN: 1573-0867
    Keywords: Ammonia volatilization ; nitrogen leaching ; denitrification ; time of N application ; wheat ; Triticum aestivum ; Triticale ; irrigation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Grain yield, nitrogen (N) assimilation, ammonia (NH3) volatilization, denitrification and fertilizer N distribution were examined in three commercially grown cereal crops; two were sown into conventionally tilled fields, while the third was direct drilled into an untilled field. The crops were top dressed with urea at establishment, tillering or ear initiation. Crop yield and N assimilation were measured in 16 m by 2.5 m plots receiving 0, 35, 70, 105, 140 or 175 kg N ha−1. A mass balance micrometeorological technique was used to measure NH3 volatilization, and other fertilizer N transformations and transfers were studied using15N labelled urea in microplots. On the conventionally tilled sites application of urea increased the grain yield of wheat from 3.9 to 5.5 t ha−1, when averaged over the five application rates, three application times and two sites. There were no site or application time effects. However, on the direct drilled site, time of application had a significant effect on grain yield. When urea was applied at establishment, grain yield was not significantly increased and the mean yield (2.81 t ha−1) was less than that obtained from treatments fertilized at tillering or ear initiation (4.09 and 4.0 t ha−1, respectively). Much of the variation in grain yield at the no-till site could be ascribed to differences in NH3 volatilization. At the no-till site, NH3 losses were equivalent to 24, 12 and 1% of the N applied at establishment, tillering and ear initiation, respectively. Negligible volatilization of NH3 occurred at the other sites. The surface soil at the no-till site had the highest urease activity and the soil was covered with alkaline ash resulting from stubble burning. Plant recovery of fertilizer N did not vary with application time on conventionally tilled sites (mean 62%). However, plant recovery of15N applied to the no-till site at establishment (35% of the applied N) was significantly less than that from plots where the application was delayed (45% at tillering and 55% at ear initiation, respectively). Leaching of N to below 300 mm depth was minimal (0 to 5% of the applied N). The calculated denitrification losses ranged from 1% to 14% of the applied N. The results show that the relative importance of NH3 volatilization, leaching and denitrification varied with site and fertilization time. The importance of the various N loss mechanisms needs to be taken into account when N fertilization strategies are being developed.
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  • 24
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    Development genes and evolution 191 (1982), S. 205-207 
    ISSN: 1432-041X
    Keywords: Chitin inhibition ; Nikkomycin ; Cuticle ; Electron microscopy ; Epilachna varivestis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nucleoside antibiotic nikkomycin has proved to be an effective inhibitor of chitin synthesis in the Mexican bean beetleEpilachna varivestis. Ultrastructural investigations show defects in the procuticular area after nikkomycin application which suggest the complete absence of chitin. A cuticle like this is inflexible and too brittle to satisfy its normal function as an exoskeleton. The individuals are not able to free themselves from the exuvia and finally die. Therefore nikkomycin seems to be a potential insecticide with high specifity.
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  • 25
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    Calcified tissue international 33 (1981), S. 143-151 
    ISSN: 1432-0827
    Keywords: Calcium transport ; Cytochalasin B ; Dihydrocytochalasin B ; Colchicine ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary In vivo calcium absorption was studied in normal and rachitic chicks. Cytochalasin B (CB) at a concentration of 25 µg/ml added to the medium inside the duodenal lumen inhibited calcium absorption (20 min) from 82.5±1.9% of calcium absorbed in the controls to 59.2±3% in normal and from 70.0±2.3% to 47.0±2.1% in rachitic chicks. In vitro studies by everted ileal sacs of young rabbits also showed an inhibition of active transport of calcium due to CB. Whereas in the controls the ratio of45Ca concentrations in serosal and mucosal media (60 min) was 7.2±0.32, the ratios were 5.24±0.52; 4.40±0.36; 3.40±0.42; 5.77±0.52; 1.38±0.08; and 1.06±0.02 in the presence of CB at concentrations of 5, 10 and 25 µg/ml; colchicine 10−4M, Na citrate 0.02M, and heat-devitalized conditions, respectively.45Ca concentration in the mucosal scrapings was also affected. It showed an increase from controls (15,101±404 cpm/mg) and correlated with CB concentration: 17,378±489, 19,015±1000, and 20,201±362 at 5, 10, and 25 µg/ml, respectively. Dihydrocytochalasin B also inhibited active calcium transport and caused an increase in45Ca concentration in the mucosal scrapings. Correlated electron microscopic studies showed certain changes in the brush border, especially in some actin microfilaments in the terminal web region. It seems that these morphological alterations may be related to transcytoplasmic movement of calcium.
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  • 26
    ISSN: 1432-0827
    Keywords: Alcohol ; Electron microscopy ; Growth plate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary We have previously demonstrated that ethanol has a direct toxic effect on the rat skeleton characterized by decreased trabecular bone volume. In the present study, we examined the ultrastructure of the distal radial epiphyseal growth plates in these same animals. Eight weeks of ethanol administration to 12 male rats results in serum alcohol levels of 140 mg/dl but did not alter the width or light microscopic appearance of the radial growth plate. Quantitative electron microscopy failed to demonstrate morphologic evidence of toxicity in the skeletal cells. We conclude that although ethanol appears to have a direct effect on rat bone characterized by enhanced resorption, toxicity is not attended by ultrastructural changes in the skeletal cells.
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  • 27
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    Calcified tissue international 33 (1981), S. 529-540 
    ISSN: 1432-0827
    Keywords: Bone cells ; Electron microscopy ; PTH ; PGE1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Four different cell populations—designated PF, OB, OC, and PC—were isolated from calvaria of 18-day-old chick embryos for analysis of the effects of hormones on bone tissue. The cell populations were studied with histological and biochemical methods. Apart from the well-known cell types present in calvaria, a new cell type was found in the noncalcified organic matrix between the osteoblastic layer and the calcified matrix. These cells were provisionally called osteocytic osteoblasts. They represent the “transition state” between osteoblasts and osteocytes. On the basis of histological studies with light microscopy (LM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), the PF population was considered to originate primarily from the periosteal fibroblasts, the OB population from the osteoblasts and osteocytic osteoblasts. The population of cells still present in calvaria after removal of periosteal fibroblasts and osteoblasts was called the OC population. This cell population was very much enriched with osteocytes. The fourth isolated population (PC) was a mixed population of fibroblasts, osteoblasts, and preosteoblasts. On exposure to parathyroid hormone (PTH), all four cell populations showed increased lactate production, but only the OB and OC populations displayed increased cAMP production. Prostaglandin E1 (PGE1) stimulated cAMP production in both OB and PF cells. From the results of this study it was concluded that PTH receptors are present on all of the cell types studied, but that occupancy of the receptor induces adenylate cyclase stimulation only in osteocytes and fully differentiated osteoblasts.
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  • 28
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    Calcified tissue international 30 (1980), S. 43-50 
    ISSN: 1432-0827
    Keywords: Osteogenesis ; In vitro ; Electron microscopy ; Mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Chick limb mesenchymal cells differentiate into muscle, cartilage, fibrous, and bone tissue. Previous reports show that when stage 24 limb mesenchymal cells are cultured in vitro, chondrocytes, myocytes, fibrocytes, and osteoblasts can be identified on the basis of morphological and biochemical parameters. The study reported here demonstrates that phenotypic expression in culture seems to be dependent on the initial plating density, Scanning electron microscopic observations indicate that when stage 24 limb mesenchymal cells are initially seeded at high densities (5 × 106 cells per 35 mm culture dish), mounds of cells appear in culture. These mounds represent cartilage nodules composed of a fine fibrous matrix and chondrocytes, surrounded by a loose fibrous connective tissue matrix. Cultures initially plated at intermediate densities (2.0–2.5 × 106 cells/35 mm culture dish) produce a flattened layer of fibrocytes overlying a matrix of collagen fibers and calcium phosphate deposits as determined by electron-microprobe analysis; these observations are indicative of osteoblast expression. Cells seeded at this intermediate density appear larger and possess greater surface area than cells seeded at high density. It is suggested that conditions that permit such increased cell surface area coupled with a relative compaction due to cell crowding may provide conditions permissive for osteogenesis. Based on morphological criteria, it appears that chick limb mesenchymal cell osteogenesis in vitro is not associated with chondrogenesis but represents a separate route of phenotypic expression.
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  • 29
    ISSN: 1432-0827
    Keywords: Rat ; Calvarium ; Electron microscopy ; Preosteoclasts ; Osteoclasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary This is a study of the fine structure of cells of the 20-day fetal rat calvarium. Special attention is given to identifying and characterizing preosteoclasts. These cells are relatively common and located largely, but not exclusively, at the endocranial bone surface. The preosteoclasts are characterized by abundant mitochondria, an incomplete perinuclear Golgi apparatus, and variable-shaped dense granules. The dense granules are unique in appearance in that they contain an internal dense matrix surrounded by a clear halo. Most granules are circular in shape but some are elongate or tubular in form. Granules with identical appearance are observed in osteoclasts. The preosteoclasts are mononucleate, or occasionally binucleate. It is suggested that because preosteoclasts are morphologically distinctive and relatively abundant, it should be feasible to separate these cells from a heterogeneous cell isolate.
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  • 30
    ISSN: 1432-0827
    Keywords: Decalcification ; Electron microscopy ; Bone matrix ; Bone glycoproteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A solution of triethylammonium EDTA in 80% ethanol was evaluated as a demineralizing reagent for bone in comparison with aqueous solutions of EDTA. Biochemical analysis and acrylamide gel electrophoresis of extracts of finely powdered bovine bone showed that most of the macromolecular components of the organic matrix extractable in aqueous EDTA were retained when the triethylammonium EDTA reagent was used. Ultrastructural examination of chick tibias decalcified with the reagents showed a better preservation of cellular morphology, especially the membranous components, and more uniformly distributed ground substance, though slightly less in quantity, when the aqueous reagent was used. Use of the two reagents appears to be complementary, the alkylammonium reagent being more appropriate for use in studies of the organic matrix of bone, including immunohistochemical studies of bone glycoproteins. The aqueous reagent is more appropriate for use in studies of cellular ultrastructure.
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    Calcified tissue international 33 (1981), S. 119-124 
    ISSN: 1432-0827
    Keywords: Avian eggshell ; Microstructure ; Electron microscopy ; Electron diffraction ; Calcite growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The eggshell of the domestic fowl has been studied by transmission electron microscopy and diffraction. Thin sections of shell were prepared by chemical and ion-beam thinning techniques. Each calcite column of the palisade layer consisted of crystallites of diameter 20 to 30 µm with some tendency for crystallite alignment within a single column. Evidence indicates that there was no significant preferred orientation in the palisade layer as a whole. Only in the surface layer was any preferred orientation detected, and here {1014} planes tended to lie parallel to the surface. The results are compared with previously published data, and calcite nucleation and growth are discussed.
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  • 32
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    Sexual plant reproduction 1 (1988), S. 217-222 
    ISSN: 1432-2145
    Keywords: Triticum aestivum ; Cytology ; In vitroandrogenesis ; Fluorescent microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two winter wheat genotypes (‘Diószegi 200’ and ‘Mv 15’) were compared for their in vitro androgenic capacity. On average, the induction frequency of embryogenic structures was 71.7% in ‘Diószegi 200’ and only 4.3% in ‘Mv 15’. The haploid induction ability of the two genotypes differed considerably, with ‘Diószegi 200’ being much higher. The difference in the in vitro inductability of the microspores may result from genetic differences which are manifested in the survival rate of the microspores during the culture period and their adaptability to in vitro conditions. Special DNA fluorochrornes were suitable for studying the different pathways of in vitro androgenesis. Our data indicate that the repeated equal divisions of the microspore nucleus might lead to pollen embryo formation, and subsequent divisions of the vegetative portion of the pollen grain after the first asymmetric microspore mitosis can result in pollen callus formation.
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  • 33
    ISSN: 1432-2145
    Keywords: Pollen development ; Triticum aestivum ; RH0007
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A study of pollen development in wheat was made using transmission electron microscopy (TEM). Microspores contain undifferentiated plastids and mitochondria that are dividing. Vacuolation occurs, probably due to the coalescence of small vacuoles budded off the endoplasmic reticulum (ER). As the pollen grain is formed and matures, the ER becomes distended with deposits of granular storage material. Mitochondria proliferate and become filled with cristae. Similarly, plastids divide and accumulate starch. The exine wall is deposited at a rapid rate throughout development, and the precursors appear to be synthesized in the tapetum. Tapetal cells become binucleate during the meiosis stage, and Ubisch bodies form on the plasma membrane surface that faces the locule. Tapetal plastids become surrounded by an electron-translucent halo. Rough ER is associated with the halo around the plastids and with the plasma membrane. We hypothesize that the sporopollenin precursors for both the Ubisch bodies and exine pollen wall are synthesized in the tapetal plastids and are transported to the tapetal cell surface via the ER. The microspore plastids appear to be involved in activities other than precursor synthesis: plastid proliferation in young microspores, and starch synthesis later in development. Plants treated with the chemical hybridizing agent RH0007 show a pattern of development similar to that shown by untreated control plants through the meiosis stage. In the young microspore stage the exine wall is deposited irregularly and is thinner than that of control plants. In many cases the microspores are seen to have wavy contours. With the onset of vacuolation, microspores become plasmolyzed and abort. The tapetal cells in RH0007-treated locules divide normally through the meiosis stage. Less sporopollenin is deposited in the Ubisch bodies, and the pattern is less regular than that of the control. In many cases, the tapetal cells expand into the locule. At the base of one of the locules treated with a dosage of RH0007 that causes 95% male sterility, several microspores survived and developed into pollen grains that were sterile. The conditions at the base of the locule may have reduced the osmotic stress on the microspores, allowing them to survive. Preliminary work showed that the extractable quantity of carotenoids in RHOOO7-treated anthers was slightly greater than in controls. We concluded that RH0007 appears to interfere with the polymerization of carotenoid precursors into the exine wall and Ubisch bodies, rather than interfering with the synthesis of the precursors.
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  • 34
    ISSN: 1432-0983
    Keywords: Electron microscopy ; Replicative intermediates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Some physicochemical properties of the mitochondrial DNAs (mtDNA) from plants of flax, broad bean and mung bean, and from tissue culture cells of jimson weed, soybean, petunia and tobacco were determined. Circular molecules were observed in electron microscope preparations of each mtDNA. In soybean, petunia, broad bean and mung bean mtDNAs, the circular molecules had a continuous distribution of lengths (ranges between 1 to 36 kb, and 1 to 126 kb), heavily skewed toward smaller molecules. Eighty-six percent of the flax circular molecules were from 27 to 54 kb in size, and 78% of the jimson weed circular molecules were from 4 to 15 kb. Replicative forms of 1.2–1.6 kb circular molecules were observed in electron microscope preparations of broad bean mtDNA.
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  • 35
    ISSN: 1432-0983
    Keywords: Triticum aestivum ; Tissue culture ; Mitochondrial DNA ; Genomic variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Wheat mitochondria) DNA has been isolated from callus cultures initiated from both immature embryos and the corresponding parental cultivar. A Sall restriction pattern study has shown that the organization of callus culture mitochondria) DNA underwent extensive change, characterized by either the disappearance or the decrease in the relative stoichiometry of several restriction bands. Hybridization of labelled mitochondrial fragments obtained from a recombinant cosmid library to Southern blots of callus and parental line restricted mitochondria) DNAs has shown that a fraction of the mitochondria) genome was lost in callus cultures. Data from a Sall + HindIII restriction map of a defined part of the wheat mitochondria) genome concerned with some of these variations strongly suggest that the observed variations correspond to the disappearance of at least one mitochondria) DNA subgenomic molecule in callus cultures.
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  • 36
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    European biophysics journal 7 (1981), S. 209-212 
    ISSN: 1432-1017
    Keywords: Photosynthetic bacteria ; Electron microscopy ; Planar lattices
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The thylakoids of Rhodopseudomonas viridis have been studied by freeze-fracturing whole cells. Depending on growth conditions and treatment before freezing, three different types of particle arrangements in the photosynthetic membrane are reported: a random arrangement, an isometric (quadratic) lattice arrangement with a lattice constant of 12.5 ± 0.8 nm, and a hexagonal lattice arrangement with a lattice constant of 12.5 ± 0.8 nm.
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  • 37
    ISSN: 1432-0789
    Keywords: Rhizosphere bacteria ; Nitrogenase activity ; Triticum aestivum ; Inoculation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Wheat seedlings were inoculated with rhizosphere nitrogen-fixing bacteria and grown gnotobiotically for 15 days. The growth medium consisted of semisolid agar with or without plant nutrients. The bacteria, isolated from roots of field-grown wheat, were three unidentified Gram-negative rods (A1, A2, E1), one Enterobacter agglomerans (C1) and two Bacillus polymyxa (B1, B2). A strain of Azospirillum brasilense (USA 10) was included for comparison. Nitrogenase activity (acetylene reduction activity, ARA) was tested on intact plants after 8 and 15 days of growth. In semisolid agar without plant nutrients, five isolates showed ARA of 0.01–0.9 nmol C2H4 plant−1 h−1, while the two strains of B. polymyxa had higher ARA of 3.3–10.6 nmol C2H4 plant−1 h−1. Plant development was not affected by inoculation with bacteria, except that inoculation with B. polymyxa resulted in shorter shoots and lower root weight. Transmission electronmicroscopy of roots revealed different degrees of infection. A. brasilense, A1 and A2, occurred mainly in the mucilage on the root surface and between outer epidermal cells (low infectivity). B. polymyxa strains and E1 were found in and between epidermal cells (intermediate infectivity) while E. agglomerans invaded the cortex and was occasionally found within the stele (high infectivity).
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  • 38
    ISSN: 1432-0983
    Keywords: Allomyces macrogynus ; Mitochondrial DNA ; Electron microscopy ; Restriction enzyme map
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mitochondrial (mt) DNA of the aquatic phycomycete Allomyces macrogynus is a circular molecule with a size of 56.1 kbp. The cleavage sites for the restriction enzymes SalI and PvuI were mapped by comparing the partial denaturation patterns of isolated restriction fragments with the pattern of the intact circle. The genes coding for the small and large ribosomal RNA (rRNA) were located on the restriction map by heteroduplex and R-loop analysis. The gene coding for the large rRNA contains an intervening sequence, app. 0.7 kbp in size, near the 3′-end of the gene. The two rRNA genes are encoded on the same strand of the mtDNA and separated by a region of 17–18 kbp. This rRNA gene organization is similar to that found with members of the Ascomycetes.
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  • 39
    ISSN: 1432-072X
    Keywords: Allomyces ; Zoospores ; Cell wall ; Chitin ; Gamma particle ; Encystment ; Electron microscopy ; Calcofluor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Structural changes during cell wall formation by populations of semisynchronously germinating zoospores were studied in the water mold Allomyces macrogynus. Fluorescence microscopy using Calcofluor white ST (which binds to β-1,4-linked glycans) demonstrated that Calcofluor-specific material was deposited around most cells between 2–10 min after the induction of encystment (beginning when a wall-less zoospore retracts its flagellum and rounds up). During the first 15 min of encystment there was a progressive increase in fluorescence intensity. Ultrastructural analysis of encysting cells showed that within 2–10 min after the induction of encystment small vesicles 35–70 nm diameter were present near the spore surface, and some were in the process of fusing with the plasma membrane. The fusion of vesicles with the zoospore membrane was concomitant with the appearance of electron-opaque fibrillar material outside the plasma membrane. Vesicles similar to those near the spore surface were found within the gamma (γ) particles of encysting cells. These particles had a crystalline inclusion within the electron-opaque matrix. During the period of initial cyst cell wall formation numerous vesicles appeared to arise at the crystal-matrix interface. Approximately 15–20 min was required for the cell wall to be formed. We suggest that the initial response of the zoospore to induction of encystment is the formation of a cell wall mediated by the fusion of cytoplasmic vesicles with the plasma membrane.
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    Archives of microbiology 130 (1981), S. 125-128 
    ISSN: 1432-072X
    Keywords: Rhodospirillum rubrum ; Chromatophores ; Reaction centers ; Liposomes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In freeze-fractures of chromatophores of Rhodospirillum rubrum the reaction centers are seen as hexagonal arranged particles of 13 nm diameter with a density of around 5,500 particles per μm2. Similar regions on the cytoplasmic membrane suggest that these parts are the prospective invagination sites. Isolated reaction centers are easily incorporated into liposomes. In freeze fractures of liposomes particles similar in shape and size, although less dense as in chromatophores are observed. In negative staining much smaller units of only 5 nm in diameter are found indicating that reaction centers occur in the membrane as tri- or tetramers. There is a strong correlation between particle density in chromatophores and titratable reaction centers remaining in these membranes after extraction of reaction centers by detergents; both values are in good agreement with the yield of reaction centers at a given detergent concentration.
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  • 41
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    Archives of microbiology 142 (1985), S. 333-339 
    ISSN: 1432-072X
    Keywords: Photosynthesis ; Membrane structure ; Electron microscopy ; Photosynthetic bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The organization of photosynthetic membranes in the cytoplasm of the photosynthetic bacterium Rh. viridis has been examined by several techniques for electron microscopy. Thin sections of membrane stacks show that the regular lattice of membrane subunits reported in other studies can be observed in thin section. Tilting of sections in the electron microscope shows that the regular lattices of several membranes overlap in a way that suggests they are in register with each other. This observation can be confirmed by freeze-fracture images in which a regular arrangement of membrane lattices can be observed, each perfectly aligned. Analysis of the spacings of membrane pairs shows that the photosynthetic membranes of Rh. viridis are very closely apposed. The mean diameter of two membranes is 160A, and the average space between two such membranes is only 42A. When a recently developed atomic level model of Rh. viridis reaction center is superimposed against these spacings, each reaction center extends from the surface of its respective membrane far enough to make contact with an apposing membrane. The limited free space between membranes and regular alignment of lattices has a number of implications for how this membrane is organized to carry out the process of energy transfer.
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  • 42
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    Archives of microbiology 146 (1986), S. 267-274 
    ISSN: 1432-072X
    Keywords: Photosynthesis ; Membrane structure ; Electron microscopy ; Ectothiorhodospira ; Serial thin sectioning ; Three dimensional reconstruction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The three dimensional organization of the complete photosynthetic apparatus of the extremely halophilic, bacteriochlorophyll b containing Ectothiorhodospira halochloris has been elaborated by several techniques of electron microscopy. Essentially all thylakoidal sacs are disc shaped and connected to the cytoplasmic membrane by small membraneous “bridges”. In sum, the lumina of all thylakoids (intrathylakoidal space) form one common periplasmic space. Thin sections confirm a paracrystalline arrangement of the photosynthetic complexes in situ. The ontogenic development of the photosynthetic apparatus is discussed based on a structural model derived from serial thin sections.
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  • 43
    ISSN: 1432-072X
    Keywords: Acidaminococcus fermentans ; Glutamate fermentation ; Electron microscopy ; Immunocytochemistry ; Post-embedding labelling ; Antibody-gold complexes ; Protein A-gold complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have investigated the in situ location of glutaconyl-CoA decarboxylase and 2-htdroxyglutaryl-CoA dehydratase in Acidaminococcus fermentans using the antibody-gold and protein A-gold techniques carried out as a post-embedding immunoelectron microscopic procedure. Polyclonal antisera were raised in rabbits against homogeneous fractions of the enzymes. Anaerobically grown cells of A. fermentans of the late exponential growth phase were fixed with 0.2% glutaraldehyde and 0.3% formaldehyde (final concentrations) in the growth medium. Dehydration of the cells was achieved with methanol. The cells were embedded in the low temperature embedding resin Lowicryl K4M. The markers indicative for antigenic sites of the two enzymes unequivocally demonstrate that the sodium pump glutaconyl-CoA decarboxylase is located at the cell periphery being a membrane-bound enzyme as expected whereas 2-hydroxyglutaryl-CoA dehydratase is a soluble cytoplasmic enzyme.
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  • 44
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    Archives of microbiology 126 (1980), S. 277-283 
    ISSN: 1432-072X
    Keywords: Bacteriophage ; Myxococcus ; λ ; Superooiled DNA ; Cross-linking ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract DNA was partially released from the heads of myxococcus phages and also coliphage λ and examined by electron microscopy by a modification of the Kleinschmidt technique, in which water was used as hypophase. DNA emerged from the heads in patterns suggestive of newly relaxed supercoils. The unreleased DNA appeared to occupy discrete regions in the head. Some closed circles were released from λ heads. When NaCl solution was used as hypophase, the DNA was observed either released from the tail or from the head, in the latter case, supercoiled regions were observed. When NH4OAc solution was used as hypophase, tightly wound structures were released from λ heads; these fields also contained supercoiled circles. The presence of constrained supercoiled domains in newly released phage DNA was confirmed by observing the effects of ethidium bromide on its conformation. Treatment of phage with nitrogen mustard, a bifunctional alkylating agent, preserved supercoiled domains, even when the phage were lysed over water as hypophase. Further experiments suggested that phage inactivation by nitrogen mustard is largely due to restraint of the supercoiled, native, tertiary structure and that DNA-protein cross-linking may be involved in this reaction. The implications of these findings for the conformation of phage DNA in vivo are discussed and a new model for the winding of DNA in phage heads is proposed.
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  • 45
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    Archives of microbiology 129 (1981), S. 129-134 
    ISSN: 1432-072X
    Keywords: Cockroach ; Hindgut ; Distribution ; Microbial morphotypes ; Transmission ; Electron microscopy ; Statistical analysis ; Eublaberus posticus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relative numbers of fourteen microbial morphotypes in transmission electron micrographs of the hindgut of a cockroach, Eublaberus posticus, were counted and their distribution was analyzed statistically. The microbiota of three wall-associated regions (the anterior paunch, the posterior paunch, and the black band region) was clearly different from that of the gut lumen. The three wall fractions were also significantly different from each other. Only one of the fourteen types, prosthecate bacteria, appeared to be distributed randomly in the four fractions. The five main wall-associated morphotypes individually constituted up to 41% of the microbes in some micrographs. They included one type with the characteristic morphology of Methanospirillum. Six morphotypes rarely made up over 2% of the population, but were consistently present. The numbers of the remaining three morphotypes were quite variable between micrographs and between individual insects, but when present often made up 5–10% of the population.
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  • 46
    ISSN: 1432-072X
    Keywords: Biological control ; Cyanobacteria ; Electron microscopy ; Entrapment ; lysis ; Myxococcus ; Phormidium ; Spherule
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    Notes: Abstract A Myxococcus xanthus isolate from a farm drainage ditch, designated strain PCO2, is capable of rapidly inducing lysis of both agar and liquid-grown cultures of the cyanobacterium, Phormidium luridum, var. olivacea. Microscopic studies of the predator-prey interaction demonstrate that lysis of the cyanobacterium occurs within clumps and spherules formed by the cells of M. xanthus PCO2. In the earliest stage, one sees the formation of irregular microclumps of bacteria and cyanobacterial filaments. As these clumps mature, colonies 1 to 6 mm in diameter develops. The center of these densely green colonies contains cyanohacteria in various stages of degradation, while the periphery is almost exclusively a tightly woven mass of myxobacterial cells. Electron microscopy shows that long extrusions from the outer membrane of the M. xanthus PCO2 cells are involved in the formation both of initial clumps and of mature colonial spherules. These extrusions appear to efficiently entangle the cyanobacterial filaments in the culture environment. Predator-to-prey ratios of 1/10, 1/100 and 1/1,000 have resulted in cyanobacterial lysis. Because the entrapment and lysis of P. luridum filaments by M. xanthus PCO2 appears to be independent of any other heterotrophic nutritional requirement, as well as of environmental agitation, this system has potential as a biological control technique for undesirable aquatic cyanobacteria.
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  • 47
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    Archives of microbiology 138 (1984), S. 273-277 
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Secondary metabolite ; Allelopathy ; Photosynthesis ; Electron transport ; Thylakoids ; Herbicides ; Electron microscopy
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    Topics: Biology
    Notes: Abstract Cyanobacterin is a secondary metabolite produced by the cyanobacterium, Scytonema hofmanni. Highly purified cyanobacterin was found to inhibit the growth of many cyanobacteria at a minimum effective dose of 2 μg/ml (4.6 μM). The antibiotic had no effect on eubacteria including the photosynthetic Rhodospirillum rubrum. The site of action of cyanobacterin was further investigated in the unicellular cyanobacterium, Synechococcus sp. Electron micrographs of antibiotic-treated Synechococcus cells indicated that cyanobacterin affects thylakoid membrane structure. The antibiotic also inhibited light-dependent oxygen evolution in Synechococcus cells and in spheroplasts. These data support our conclusion that cyanobacterin specifically inhibits photosynthetic electron transport. This activity is similar to herbicides such as 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU). The anhydro analog of cyanobacterin had no biological activity.
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  • 48
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    Archives of microbiology 130 (1981), S. 339-343 
    ISSN: 1432-072X
    Keywords: Leptospira ; Halophilic ; Electron microscopy ; X-ray analysis ; Inclusions ; Cytoplasmic tubules
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    Topics: Biology
    Notes: Abstract The morphology of cells of strain Muggia, a slightly halophilic leptospire, was examined by the negative staining technique. The ultrastructure of the cells was rather similar to that of cells of Leptonema illini, i. e. the cells possessed cytoplasmic tubules. The basal complex of their flagella, however, was similar to the corresponding part of flagella on Gramnegative bacteria. The interior of the cells was densely packed with inclusions, except for the two outermost wavelengths at each end where these inclusions were absent. X-ray microanalysis showed that the inclusions contained sodium and chlorine as their main constituents. The inclusions disappeared upon storage of the cultures at room temperature.
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  • 49
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    Archives of microbiology 132 (1982), S. 10-13 
    ISSN: 1432-072X
    Keywords: Calcofluor White ; Cell wall structure ; Chlorella ; Electron microscopy ; Protoplast ; Ruthenium Red
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Among 12 strains ofChlorella ellipsoidea, C. vulgaris, andC. saccharophila tested, 4 strains (1,C. ellpsoidea; 2,C. vulgaris; 1,C. saccharophila) formed osmotically labile protoplasts after treatment with mixtures of polysaccharide degrading enzymes. The relationship between enzymatical digestibility and structure or composition ofChlorella cell walls were studied by electron microscopy and staining techniques with some specific dyes. The cell wall structures of the 12Chlorella strains were grouped into three types: (1) with a trilaminar outer layer, (2) with a thin outer monolayer, and (3) without an outer layer. Protoplasts were formed only from the strains with a cell wall of Type 2. In the strains with a cell wall of Type 1, the outer layer protected the inner major microfibrillar layer against enzymatic digestion. The cell wall of Type 3 was totally resistant to the enzymes; the chemical composition of the cell wall would be somewhat different from that of other types.
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  • 50
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    Archives of microbiology 135 (1983), S. 169-175 
    ISSN: 1432-072X
    Keywords: Photosynthetic membranes ; Electron microscopy ; Image processing ; Ectothiorhodospira halochloris ; Ectothiorhodospira abdelmalekii ; Rhodopseudomonas viridis ; Rhodopseudomonas sulfoviridis ; Thiocapsa pfennigii
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    Notes: Abstract The photosynthetic membranes of the five bchl b-containing bacteria Ectothiorhodospira halochloris, E. abdelmalekii, Rhodopseudomonas viridis, R. sulfoviridis and Thiocapsa pfennigii have been investigated by electron microscopy and digital image analysis. All five species have the photosynthetic complexes hexagonally arrayed in the membrane with lattice spacings close to 13 nm, except for R. sulfoviridis and T. pfennigii which display somewhat smaller (∼12.5 nm) lattice spacings. Correlation averaging which imposes less stringent requirements on the lattice perfection than conventional Fourier filtration techniques has been employed to elucidate the structure of the photosynthetic complexes. Their basic organization, i.e. a ring, probably containing the light-harvesting (LH) polypeptides, surrounding a core (the “reaction centre”) appears to be almost identical for all species under scrutiny. Despite a resolution of ∼1.6 nm, however, little further significant substructure can be deduced from the averages; possible reasons for the “blurred” appearance of the LH-ring and absence of any subdivision in the reaction centre are discussed along with strategies aimed at obtaining a more detailed model of the molecular architecture of the photosynthetic membranes.
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  • 51
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    Keywords: Bacteriolysis ; Penicillin ; Autolysis ; Cell wall ; Electron microscopy ; Staphylococcus aureus
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    Notes: Abstract The actual reason for the penicillin-induced bacteriolysis of staphylococci was shown to be the “punching” of one or a few minute holes into the peripheral cell wall at predictable sites. These perforations were the result of the lytic activity of novel, extraplasmatic vesicular structures, located exclusively within the bacterial wall material, which we have named “murosomes”. In untreated staphylococci the punching of holes into the peripheral wall is a normal process which follows cross wall completion and represents the first visible step of cell separation. Under penicillin, however, analogous holes are punched by the murosomes at sites of presumptive cell separation even if no sufficient cross wall material had been assembled before at this site (but had rather been deposited at other sites). Consequently, because of the internal pressure of the protoplast, lytic death is the inevitable result of this perforation of the protective peripheral wall. Hence, the real mechanism of penicillin-induced bacteriolysis in staphylococci is considered to be mainly the result of a special morphogenetic wall defect: bacteriolysis is taking place regularly when a cell separation process is no longer preceeded by sufficient cross wall assembly at the correct place. However, hypotheses which are based purely on some variations of overall biochemical processes like total wall enzyme activities or total wall synthesis are not regarded to be sufficient to explain this type of lytic death.
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  • 52
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    Archives of microbiology 142 (1985), S. 259-261 
    ISSN: 1432-072X
    Keywords: Methanogenic bacteria ; Plasmid isolation ; Alkaline lysis ; CsCl gradient ; Restriction endonuclease mapping ; Electron microscopy ; DNA homology
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    Notes: Abstract Of 21 recently isolated strains of methanococci, one was found to harbor a small, cryptic, low copy number plasmid. Reproducible recovery was achieved by alkaline lysis of cells pretreated with proteinase K in an osmotically stabilizing buffer. The plasmid was found to contain a singleAval site. No homology was detected between the plasmid and DNA from any of the other new strains or from five known species of methanococci.
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  • 53
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    Keywords: Immunoferritin labeling ; Electron microscopy ; Membrane vesicles ; Nitrate reductase ; Bacillus licheniformis ; Klebsiella aerogenes
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    Notes: Abstract The indirect immunoferritin labeling method was used to localize the membrane-bound respiratory nitrate reductase in membrane vesicles and protoplasts or spheroplasts of Bacillus licheniformis and Klebsiella aerogenes, respectively. For a comparison of the labeling of the various vesicle preparations, which differed not only in size but also in the percentage of inside-out orientation, a quantification of the results was needed to circumvent the problem of non-specifically bound ferritin. From the results the sidedness of the nitrate reductase in the cytoplasmic membrane of the abovementioned bacteria was determined as being cytoplasmic in B. licheniformis and as transmembranous in K. aerogenes.
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  • 54
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    Archives of microbiology 128 (1980), S. 12-18 
    ISSN: 1432-072X
    Keywords: Moraxella glucidolytica ; Electron microscopy ; Lipopolysaccharide
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    Topics: Biology
    Notes: Abstract A cellular (LPS I) and extracellular (LPS II) lipopolysaccharide were isolated from Moraxella glucidolytica cells grown on ethanol and from the culture fluid, respectively. Both LPS were toxic when injected to mice and chick embryos. These LPS contained glucose, galactose, glucosamine, galactosamine, 2-keto-3-deoxyoctonate and lipids. By permethylation studies, glucose was found to be linked (1→6) and (1→3) in LPS I and only (1→6) in LPS II. Galactose was the terminal non-reducing sugar. Branching occurred at positions 3 and 4 of galactose residues. LPS I was rich in α- and β-hydroxylauric and α-hydroxymyristic acids and LPS II contained mainly stearic and α-hydroxymyristic acids. LPS I was detoxified by mild acid and alkaline treatments. It was also dissociated by sodium deoxycholate and chromatographed on Sephadex G-75. The main fraction was reassociated by removing the surfactant by dialysis. The morphology of LPS I and LPS II was examined by electron microscopy. LPS I (original and reassociated fractions) consisted exclusively of ribbons while LPS II contained ribbons and vesicles.
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  • 55
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    Keywords: Ribulose bisphosphate carboxylase ; Quaternary structure ; Molecular weight ; Electron microscopy ; Cyanobacteria ; Synechococcus
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    Notes: Abstract Ribulose bisphosphate (RuP2) carboxylase from the marme cyanobacterium, Synechococcus sp., comprised both large (57,000 dalton) and small (12,000 dalton) subunits. The undissociated, purified enzyme was considerably smaller than the spinach enzyme when compared by pore-gradient electrophoresis, gel filtration and density-gradient centrifugation. This suggested that the cyanobacterial enzyme might have a hexameric (L6S6) subunit structure, unlike the enzymes from spinach and many other organisms which are octamers (L8S8). However, the molecular weight of the Synechococcus enzyme was measured by equilibrium sedimentation and found to be 530,000, which is within the range observed for L8S8-type enzymes. Furthermore, electron microscopic studies of negatively stained preparations of both the native enzyme, and a preparation depleted of 87% of its small subunits by repeated mild-acid precipitation, revealed four-fold symmetry characteristic of an octameric, cubical structure. Synechococcus RuP2 carboxylase therefore must be an L8S8 octamer and its anomalous pore-penetration behaviour may be due to an asymmetric shape. Some support for the latter possibility was provided by electron miscoscopic observations of two different types of images which may be different views of the molecule in two planes.
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  • 56
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    Archives of microbiology 140 (1984), S. 265-270 
    ISSN: 1432-072X
    Keywords: EcoRI ; EcoRI-DNA complexes ; EcoRI* activity ; Recognition sites ; Frequency of binding ; Electron microscopy
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    Topics: Biology
    Notes: Abstract Electron microscopy of negatively stained isolated restriction enzyme EcoRI revealed particle projections with triangular or square outlines, indicating that the enzyme, in its tetrameric state, is tetrahedron-like. The two dimers making up the tetramer appear to be arranged in two planes orthogonal to each other. Complexes formed by EcoRI with the plasmids pBR322 or pGW10 were investigated by electron microscopic spreading techniques. In the presence of Mg2+, EcoRI was bound to the DNA molecules to form pearl necklace-like aggregates. The number of bound EcoRI particles was much higher as the sum of EcoRI-and 5′..AATT..3′ sites (with exceptions, the 5′..AATT..3′ sites may function as one type of EcoRI* sites) along the DNAs, indicating unspecific binding. In the absence of Mg2+, EcoRI was bound to the DNA only at the recognition site for EcoRI and the sites where the tetranucleotide sequence 5′..AATT..3′ was present. A direct correlation of the local concentrations of the bases A and T within the flanking sequences of the binding sites with the frequency of EcoRI to the DNA was observed. Dimers and tetramers of the enzyme was found to bind to the DNA. Tetramers occasionally exhibited two binding sites for DNA as indicated by the observation of DNA loops originating at the sites of bound tetrameric EcoRI particles.
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  • 57
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    Archives of microbiology 140 (1985), S. 338-342 
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    Keywords: Sporosarcina halophila ; Endospores ; Electron microscopy ; Heat resistance ; Ethanol resistance ; Germination ; Dipicolinic acid
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    Notes: Abstract Sporosarcina halophila forms endospores. Electron micrographs revealed ultrastructural similarity to spores of S. ureae. Spore germination indicated by loss of refractility, darkening, swelling and formation of new vegetative cells was followed by phase contrast light microscopy. To induce spore germination, the endospores needed to be heat avtivated. After activation, they were inoculated into nutrient broth medium supplemented with sea-water. Double concentrated sea-water was found to be optimal for germination. Similar to other bacterial endospores, the spores were found to be resistant to heat and ethanol. An ultraviolet absorbing substance was isolated from suspensions of free spores; it was identified to be pyridine-2,6-dicarboxylic acid (DPA) usually present in bacterial spores. DPA was detected in amounts ranging from 5–7% of the spore dry weight; it was not detected in extracts of vegetative cells.
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  • 58
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    Archives of microbiology 141 (1985), S. 85-90 
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    Keywords: C. sporosphaeroides ; Citrate lyase ; Regulation ; Purification ; Properties ; Electron microscopy
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    Notes: Abstract Cells of Clostridium sporosphaeroides which were grown on citrate contained citrate lyase and citrate lyase acetylating enzyme, but no detectable citrate synthase and citrate lyase deacetylase activities. Citrate lyase from C. sporosphaeroides was purified to homogeneity as judged by polyacrylamide gel electrophoresis and high performance liquid chromatography. In contrast to the enzyme from Clostridium sphenoides, the addition of l-glutamate was not necessary for activity and stabilization of the enzyme. The purified enzyme had a specific activity of 34 U/mg protein and was comparable to other citrate lyases with respect to its molecular weight and subunit composition. Electron microscopic investigations showed that similar to the lyase from C. sphenoides and in contrast to all other citrate lyases examined so far, the majority of the enzyme molecules was present in “star” form.
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  • 59
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    Archives of microbiology 143 (1986), S. 400-402 
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    Keywords: E. coli relA +/relA ; Starvation survival ; Guanosine tetraphosphate ; Electron microscopy ; Glycogen
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    Notes: Abstract Amino acid-starved cells of Escherichia coli relA +, which contain a large number of glycogen particles, are able to survive in phosphate buffer for a longer time period than their relaxed counterparts. With regard to NH 4 + starvation differences in the survival of both strains were not found. NH 4 + starved cells of E. coli relA are able to synthesize glycogen but amino acid-starved cells of the relA strain are not. We suggest that the synthesis of glycogen triggered by guanosine tetraphosphate during amino acid starvation is responsible for the prolonged viability of the E. coli relA + strain.
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  • 60
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    Keywords: Bradyrhizobium ; Electron microscopy ; Mutants ; Nitrogen fixation ; Nodulation ; Soybean ; Symbiosis ; Transposon Tn5
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    Notes: Abstract The genome of the slow-growing Bradyrhizobium japonicum (strain 110) was mutagenized with transposon Tn5. A total of 1623 kanamycin/streptomycin resistant derivatives were screened in soybean infection tests for nodulation (Nod) and symbiotic nitrogen fixation (Fix). In this report we describe 14 strains possessing a stable, reproducible Nod+Fix- phenotype. These strains were also grown under microaerobic culture conditions to test them for free-living nitrogen fixation activity (Nif). In addition to strains having reduced Fix and Nif activities, there were also strains that had reduced symbiotic Fix activity but were Nif+ ex planta. Analysis of the genomic structure revealed that the majority of the strains had a single Tn5 insertion without any further apparent physical alteration. A few strains had additional insertions (by Tn5 or IS50), or a deletion, or had cointegrated part of the vector used for Tn5 mutagenesis. One of the insertions was found in a known nif gene (nifD) whereas all other mutations seem to affect different, hitherto unknown genes or operons. Several mutant strains had an altered nodulation phenotype, inducing numerous, small, widely distributed nodules. Light and electron microscopy revealed that most of these mutants were defective in different stages of bacteroid development and/or bacteroid persistence. The protein patterns of the mutants were inspected by two-dimensional gel electrophoresis after labelling microaerobic cultures with l-(35S)methionine. Of particular interest were mutants lacking a group of proteins the synthesis of which was known to be under oxygen control. Such strains can be regarded as potential regulatory mutants.
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  • 61
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    Keywords: Aggregation substance ; Enterococcus faecalis ; Electron microscopy ; Field emission scanning electron microscopy ; Immunogold labelling technique ; Sex pheromone system
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    Notes: Abstract The distribution of sex pheromone induced aggregation substance was studied on the cell surface of various Enterococcus faecalis strains. In the accompanying paper we have shown that the aggregation substance appears as a layer of hairlike structures. Using direct and indirect immunogold technique, transmission electron microscopy and high resolution scanning electron microscopy we investigated the appearance and distribution of the aggregation substance. The “hairs” increase in number with increasing exposure to sex pheromones (maximum density: 1300/μm2). We show that these structures are unequally distributed over the cell surface, even if the cells were induced by sex pheromones for a long period of time. Statistical analysis of the unequal distribution indicates that aggregation substance is incorporated into pre-existing “old” cell-walls and that this incorporation shows a saturation ca. 40 min after addition of sex pheromones.
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  • 62
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    Archives of microbiology 126 (1980), S. 87-95 
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    Keywords: Ascodichaena ; Beech bark ; Electron microscopy ; Host-fungus relationship
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    Notes: Abstract Ascodichaena rugosa Butin is a corkinhabiting fungus, found frequently on the bark of Fagus sylvatica L. The hyphae of the fungus are distributed solely in the phellem cells, stopping their growth in the last-formed cork cell layer. The cell to cell invasion is effected by penetration hyphae, causing no extensive dissolution of the cork wall. Electron microscopical observations revealed fine structural details of the fruit bodies and of the intracellular hyphae. Of special interest were the finger-like hyaline hyphae in the last-formed layer of cork cells, which are interpreted as haustoria on the basis of the fine structure both of hyphae and host cells. This situation is considered as reflecting a parasitic relationship of Ascodichaena to beech bark. The activity of the fungus led also to the increased production of cork cells, perhaps related to the nutrient supply of the fungus.
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  • 63
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    Archives of microbiology 133 (1982), S. 97-99 
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Thylakoid centers ; Photosynthetic membranes/thylakoids ; Membranes ; Membrane biogenesis ; Electron microscopy
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    Notes: Abstract An ultrastructural study of four cyanobacteria (Anabaena cylindrica, Dermocarpa violaceae, Gleocapsa alpicola, Pleurocapsa minor) indicates the presence of previously undescribed thylakoid centers from which photosynthetic membranes (thylakoids) radiate. These peripherally located thylakoid centers are cylinders 30 nm wide by 320 nm long, consisting of globular subunits oriented in nonparallel stacked arrays. Thylakoids are attached to the outer surface of the cylinder along its longitudinal axis. Thylakoid centers appear to be functionally significant due to their structure, location and thylakoid association.
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  • 64
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    Archives of microbiology 135 (1983), S. 25-29 
    ISSN: 1432-072X
    Keywords: Electron microscopy ; Euglena mutabilis ; Flagellate ; Photomovement ; Photoreceptor ; Phototaxis ; Single-cell analysis ; Videomicroscopy
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    Topics: Biology
    Notes: Abstract Due to the lack of an emergent flagellum the green flagellate Euglena mutabilis is restricted to gliding motility. During forward movement, the organisms orient positive phototactically in the presence of a suitable light stimulus. The cell contains both a stigma and a paraflagellar body which differ in shape and size from the organelles found in E. gracilis. The degree of orientation in white light follows an optimum curve with a maximum at about 100 lx. The spectral sensitivity shows a number of prominent peaks in the blue and green regions and extends well into the red region of the visible spectrum. Since the cell does not rotate during locomotion a periodic shading mechanism cannot account for phototactic orientation. Thus, phototaxis in the related species, E. gracilis and E. mutabilis differ in their photoreceptor molecules, their sensory transduction chains and their strategies of light direction detection.
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  • 65
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    Archives of microbiology 131 (1982), S. 116-123 
    ISSN: 1432-072X
    Keywords: Cell wall ; Wall degradation ; Lysozyme ; Autolysines ; Electron microscopy ; Staphylococcus aureus
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    Topics: Biology
    Notes: Abstract In contrast to former findings lysozyme was able to attack the cell walls ofStaphylococcus aureus under acid conditions. However, experiments with14C-labelled cell walls and ribonuclease indicated that, under these conditions, lysozyme acted less as an muralytic enzyme but more as an activator of pre-existing autolytic wall enzymes. Electron microscopic studies showed that under these acid conditions the cell walls were degraded by a new mechanism (i.e. “attack from the inside”). This attack on the cell wall started asymmetrically within the region of the cross wall and induced the formation of periodically arranged lytic sites between the cytoplasmic membrane and the cell wall proper. Subsequently, a gap between the cell wall and the cytoplasmic membrane resulted and large cell wall segments became detached and suspended in the medium. The sequence of lytic events corresponded to processes known to take place during wall regeneration and wall formation. In the final stage of lysozyme action at pH 5 no cell debris but “stabilized protoplasts” were to be seen without detectable alterations of the primary shape of the cells. At the same time long extended ribbon-like structures appeared outside the bacteria. The origin as well as the chemical nature of this material is discussed. Furthermore, immunological implications are considered.
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  • 66
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    Keywords: Thiobacillus ferrooxidans ; Sulfur production ; Sulfur oxidation ; Inhibitors ; Uncouplers ; Electron microscopy
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    Notes: Abstract The intermediary production of elemental sulfur during the microbial oxidation of reduced sulfur compounds has frequently been reported. Thiobacillus ferrooxidans, an acidophilic chemolithoautotroph, was found to produce an insoluble sulfur compound, primarily elemental sulfur, during the oxidation of thiosulfate, trithionate, tetrathionate and sulfide. This was confirmed by light and electron microscopy. Sulfur was produced from sulfide by an oxidative step, while the production from tetrathionate was initiated by a hydrolytic step, probably followed by a series of chemical reactions. The oxidation of intermediary sulfur was severely inhibited by sulfhydryl-binding reagents such as N-ethylmaleimide, by the addition of uncouplers or after freezing and thawing of the cells, which probably damaged the cell membrane. The mechanisms behind these inhibitions have not yet been clarified. Finally, it was observed that elemental sulfur oxidation by whole cells depended on the medium composition. The absence of sulfate or selenate reduced the sulfur oxidation rate.
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  • 67
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    Biochemical genetics 24 (1986), S. 435-446 
    ISSN: 1573-4927
    Keywords: superoxide dismutase ; Triticum aestivum ; isozymes ; isoelectric focusing ; structural genes
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Extracts of mature grains of a large number of aneuploid derivatives of Triticum aestivum cv. Chinese Spring and of the members of five wheat-alien chromosome addition series were subjected to isoelectric focusing in polyacrylamide gels in order to study the genetic control of superoxide dismutase (SOD). Evidence was obtained that homologous structural genes for the mitochondrial form of SOD are located in the long arms of the homoeologous group 2 chromosomes of Chinese Spring and in chromosome 2R of Secale cereale cv. Imperial. The SOD gene loci located in chromosomes 2A, 2B, 2D, and 2R were designated Sod-A1, Sod-B1, Sod-D1, and Sod-R1, respectively. Chromosome-arm pairing data indicate that 2DL is not homoeologous to either 2AS or 2BL. The results of this study suggest, however, that 2BL is partially homoeologous to both 2AL and 2DL.
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  • 68
    ISSN: 1573-4927
    Keywords: nitrate reductase ; Triticum aestivum ; ditelosomics
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The nitrate reductase activities (NRA) of 31 ditelosomic stocks were compared with that of the control plant [Chinese Spring (CS) euploid], using in vivo and in vitro assay procedures that had been optimized with respect to the euploid. Fourteen stocks exhibited significant differences in in vivo NRA from that of the euploid; the effect of removal of a chromosome arm was always to increase NRA. Eight of these stocks showed similar effects in vitro, although in three, a casein-sensitive factor had to be eliminated before the difference was expressed. Homoeologous group effects were evident among ditelosomics of groups 2, 4, and 7, while for three chromosomes (2D, 7A, and 7B), removal of either arm resulted in a similar increase in NRA in vivo and probably in vitro.
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  • 69
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    Biochemical genetics 25 (1987), S. 837-846 
    ISSN: 1573-4927
    Keywords: NADH dehydrogenase ; aromatic alcohol dehydrogenase ; Triticum aestivum ; isozymes ; structural genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The genetic control of NADH dehydrogenase-1 (NDH-1) and aromatic alcohol dehydrogenase-2 (AADH-2) was investigated in Triticum aestivum cv. Chinese Spring. Evidence was obtained that NDH-1 is active as a monomer and is encoded by genes located in the p arms of the homoeologous group 4 chromosomes. The NDH-1 gene loci located in 4 Ap, 4Bp, and 4Dp were designated Ndh-A1, Ndh-B1, and Ndh-D1, respectively. Aadh-A2 was previously reported to be located in 6Aq; in this study, Aadh-B2 and Aadh-D2 were localized in 6Bq and 6Dq, respectively. Alcohol dehydrogenase-1 is expressed on AADH-2 zymograms; the presence of a contaminating aliphatic alcohol in one or more reagents is suggested as the probable cause of this phenomenon.
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    Biochemical genetics 26 (1988), S. 287-301 
    ISSN: 1573-4927
    Keywords: shikimate dehydrogenase ; electrophoresis ; isoelectric focusing ; isozymest ; Triticeae ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Starch gel electrophoresis and polyacrylamide gel isoelectric focusing (IEF) were used to investigate the genetic control of Triticeae shikimate dehydrogenase-1 (SKDH-1). Studies of wheat-alien species chromosome addition lines established thatSkdh-1 ofHordeum vulgare cv. Betzes is located in chromosome 5H,Skdh-V1 ofDasypyrum villosum in 5V,Skdh-R1 ofSecale cereale cvs. Dakold and King II in 5R, andSkdh-S 11 ofTriticum longissimum in 5S1S. Also, the chromosomal locations of the genes that encode SKDH-1 inT. aestivum cv. Chinese Spring,T. umbellulatum, andS. cereale cv. Imperial, determined earlier using zone electrophoresis, were reconfirmed using IEF. Zone electrophoresis and IEF do not differ markedly in their ability to detect the expression of alienSkdh-1 genes in wheat-alien species chromosome addition lines. However, IEF may be superior to zone electrophoresis as a technique for detecting and analyzing SKDH-1 genetic variants within Triticeae species; among the species studied, IEF generally resolved two or more isozymes perSkdh-1 allele present, while zone electrophoresis resolved only one.
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  • 71
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    Plant molecular biology 11 (1988), S. 311-319 
    ISSN: 1573-5028
    Keywords: chloroplast gene ; iron-sulphur protein ; psaC ; Pisum sativum ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The gene for the 8 kDa subunit of photosystem I has been located in the small single copy region of wheat chloroplast DNA by coupled transcription-translation of cloned fragments of DNA and by DNA sequence analysis. The pea gene for this subunit was located in pea chloroplast DNA by using the wheat gene as a probe. The location was confirmed by immunoprecipitation of the products of coupled transcription-translation of cloned DNA with antiserum raised against the small subunits of pea photosystem I and by DNA sequence analysis. The deduced amino acid sequences of the pea and wheat proteins are identical in seventy-six out of the eighty-one amino acid residues. There are nine conserved cysteine residues, eight of which are arranged in the primary structure in a similar way to those in bacterial ferredoxins containing two 4Fe-4S centres, suggesting that the polypeptide binds iron sulphur centres A and B of photosystem I.
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  • 72
    ISSN: 1432-2048
    Keywords: Amyloplast DNA ; DNA accumulation ; Endosperm development ; Triticum aestivum
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    Topics: Biology
    Notes: Abstract The accumulation of amyloplast DNA during endosperm development was studied in two cultivars of spring wheat, Triticum aestivum L. ‘Chinese Spring’ (CS) and ‘Spica’, small and relatively larger-grained cultivars, respectively. Endosperms were isolated between 9 and 45 days post anthesis (dpa) and the amyloplast DNA content of endosperm nucleic-acid extracts was measured by quantitative hybridisation with a homologous chloroplast-DNA probe. The endosperm cells of CS and Spica accumulated amyloplast DNA during development in a similar way. In both cultivars there was a large increase in the amount of plastid DNA (ptDNA) per endosperm between 9 and about 15 dpa, after which there was no further increase. Because nuclear DNA continued to accumulate until 24 dpa, the percentage contribution of amyloplast DNA to total DNA fluctuated in both cultivars during development, reaching maxima at 12 dpa of about 1.00% and 0.85%, and dropping to apparently constant levels of 0.60% and 0.52% in CS and Spica, respectively, by 24 dpa. In both cultivars, the average number of ptDNA copies per amyloplast was calculated to increase from about 10 copies at 9 dpa to about 50 copies in the mature amyloplasts at 31 dpa. However, the heavier endosperms of Spica contain more cells than those of CS and the varieties therefore differed in the amount of ptDNA that accumulated per endosperm: Spica endosperms accumulated 110 ng of ptDNA by 15 dpa, compared with only 85 ng in CS. The apparent accumulation of ptDNA copies in wheat amyloplasts during endosperm development contrasts with the decline in chloroplast-DNA copies in wheat chloroplasts during leaf development.
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  • 73
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    Theoretical and applied genetics 66 (1983), S. 101-109 
    ISSN: 1432-2242
    Keywords: Anther culture ; Culture temperature ; Induction frequency ; Pollen callus (plantlet) ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The response of anther culture to culture temperature was studied in detail using many varieties, F1 hybrids and pollen-derived lines of wheat (Triticum aestivum) as materials. The suitable culture temperature for inducing pollen callus (or embryoids) in wheat anther culture ranged from 26 °C to 30 °C, varying with genotypes. But for the great majority of wheat genotypes the suitable culture temperatures lay between 28 °C and 30°C. The most significant genotypic variation in the response to culture temperature was observed in the comparison between the culture at 33 °C for eight days followed by culture at 25 °C (or 26 °C) and the continuous culture at 25 °C (or 26 °C). This genotypic variation in the response to culture temperature is a heritable character which may be controlled by multiple genes. The effect of culture at 30 °C for eight days followed by culture at 26 °C was similar to, or in some cases, better than that of continuous culture at 28 °C, and the effect of culture at 32 °C for eight days followed by culture at 28 °C was similar to that of continuous culture at 30 °C. In the range from 26 °C to 32 °C, the overwhelming majority of pollen calli emerged before the 40th day after anther inoculation, and the higher the culture temperature, the earlier and more concentrated the emerging period of the pollen callus. The pollen callus obtained at high temperatures above 28 °C should be transferred in time onto the regeneration medium at 25°–27°C to induce shoots.
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  • 74
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    Theoretical and applied genetics 64 (1983), S. 255-258 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Wheat ; Malate dehydrogenase ; Chromosomal location
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The malate dehydrogenase (E.C. no 1.1.1. 37) of Triticum aestivum L. cv. Chinese Spring, shows two activity zones. The results obtained support the hypothesis that the malate dehydrogenase isozymes of zone II are dimers composed of the six possible combinations of subunits coded by triplicate genes located in the long arms of chromosomes of the homoeologous group 1.
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  • 75
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    Theoretical and applied genetics 68 (1984), S. 335-345 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; 2D electrophoresis ; Developmental genetics ; Cytoplasmic inheritance ; Genetic regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two-dimensional gel electrophoresis of denaturated proteins were performed at five developmental stages or organs (hereafter referred to as stage-organs) on two wheat lines with four different cytoplasms. Five hundred and fifty to 712 reproducible spots were scored depending on the stage-organ. Each stage-organ is unambiguously characterized and several types of control of protein quantity are recorded. Post-translational modifications are hypothetized and may sometimes be stagespecific. Two cytoplasmic patterns are found: one for the euplasmic lines with Triticum aestivum cytoplasm and one for the alloplasmic lines with Aegilops juvenalis, Ae. ventricosa and Ae. kotschyi cytoplasms. Cytoplasmic variation is observed for 28 spots showing position difference, all of which are probably products of the LS gene, and for four spots showing differences for regulation of protein quantity. Nuclear variation between ‘Chinese Spring’ and ‘Selkirk’ is found for 20 allelic differences and for 20 regulatory systems, the latter number being probably underestimated.
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  • 76
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    Theoretical and applied genetics 71 (1985), S. 31-38 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; 2D electrophoresis ; Gene localization ; Homoeologous genes ; Genetic regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Among the 782 spots observed in two-dimensional gel electrophoresis of denatured proteins from etiolated wheat shoots, 185 were found to be variable between the euploid and 26 ditelosomic lines of ‘Chinese Spring’. Thirty-five structural genes were located on 17 chromosome arms. Numerous intensity changes showing alterations in protein levels were observed and led to the following statements: 1) regulators are frequently found and can be assigned for a same polypeptide to various chromosome arms; 2) for most polypeptides homoeologous arms do not manifest similar effects; 3) nevertheless, when affecting the same polypeptide, homoeologous arms display in most cases identical regulatory effects; 4) gene dosage compensation is observed in only one out of four homoeoallelic situations.
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  • 77
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    Theoretical and applied genetics 73 (1986), S. 122-128 
    ISSN: 1432-2242
    Keywords: α-amylase ; Triticum aestivum ; Secale montanum ; C-banding ; Meiotic pairing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A 5BS/5RmS translocation chromosome spontaneously recovered from a ‘Chinese Spring’ — Secale montanum wheat-rye telocentric 5RmS addition line has been identified and cytologically studied using C-banding in somatic and meiotic cells. Analysis of the translocated chromosome showed that a terminal segment of the short arm of 5B had been replaced by a short terminal region of chromosome arm 5RmS. The translocation led to the deletion of the genetic system promoting pairing located in 5BS, which is slightly compensated for when doses of 5RmS are increased, indicating homoeology to wheat chromosome 5BS. The α-amylase phenotype in 5B/5Rm translocated material was studied and found to be identical to that of ditelocentric line 5BL of ‘Chinese Spring’. An effect on the α-amylase activity was detected as a result of the removal of the terminal region of 5BS, perhaps as a consequence of variation in dormancy period duration.
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  • 78
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    Theoretical and applied genetics 73 (1986), S. 246-251 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; 2D electrophoresis ; Gene localization ; Gene regulation ; Homoeology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two-dimensional gel electrophoresis was conducted on denatured proteins of the 10-day-old first leaf (1F stage) of 18 homoeologous ditelosomic (DT) lines of wheat cultivar ‘Chinese Spring’. The observations, compared to the euploid control and relative to previous data found on 7-day-old etiolated seedlings (G7 stage) of the same lines lead to the following statements: 1) the structural genes of 24 spots can be assigned to 12 chromosome arms; 2) regulatory effects are completely different between the 1F and the G7 stages which may indicate that the regulation of protein amounts is often stage-specific; 3) no case of complete gene dosage compensation is observed among 4 groups of hypothesized homoeoallelic products; 4) homoeologous DT lines do not manifest similar effects which suggest the absence of homoeology for the detected regulatory effects.
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    Theoretical and applied genetics 73 (1987), S. 459-464 
    ISSN: 1432-2242
    Keywords: β-amylase ; Isozymes ; Triticum aestivum ; Somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The progeny of 149 plants regenerated from tissue culture of immature wheat (Triticum aestivum) embryos were screened for variation in their grain β-amylase isozyme pattern. One regenerant was found which was heterozygous for a variant pattern characterized by the presence of at least five new isozyme bands, as well as an increased intensity in existing bands in two more positions. The F2 of a homozygous variant crossed back to the parent segregated in an approximate 3∶1 ratio but resolution of the gels was not sufficient to distinguish whether this represents a dominant or co-dominant single mutant gene. No chromosome abnormalities were evident in mitosis or meiosis of the homozygous variant or in the F1 of the variant crossed back to the parent. No recombination has been seen between the variant bands and production of multiple bands from a single locus is consistent with the nature of the known β-amylase loci. However, the variant bands were not evident in a survey of 111 diverse genotypes, nor were they present in developing grain of the parent cultivar. Therefore, this variant could represent a rare mutation leading to expression of a currently unexpressed locus.
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    Theoretical and applied genetics 73 (1987), S. 846-855 
    ISSN: 1432-2242
    Keywords: Puccinia graminis tritici ; Triticum aestivum ; Monosomic analysis ; Rust resistance ; Gene identification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary ‘Chris’ wheat possessed genes Sr5, Sr7a, Sr8a, Sr9g and Sr12. ‘W3746’, derived from the cross ‘Chris’/‘Baart’, possessed Sr7a and Sr12. The response conferred by Sr7a was influenced by the genetic background. Although Sr7a or Sr12 alone conferred no observable resistance upon adult plants, the adult resistances of ‘Chris’ and ‘W3746’ to predominant pathotypes appeared to be associated with the interaction of Sr7a and Sr12, or genes at closely linked loci.
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  • 81
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    Theoretical and applied genetics 74 (1987), S. 584-588 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; T. turgidum ; Aegilops squarrosa ; Cation uptake ; D genome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary K/Na ratios have been determined in the leaves of salt-treated plants of 14 disomic substitution lines in which each of the D-genome chromosomes replaces the homoeologous A- or B-genome chromosome in the tetraploid wheat variety Langdon (AABB genome). Aneuploid lines of hexaploid bread wheat (cv Chinese Spring) having a reduced or an enhanced complement of chromosome 4D have also been examined. These investigations show that the gene(s) determining K/Na ratios in the leaves of wheat plants grown in the presence of salt is located on the long arm of chromosome 4D.
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    Theoretical and applied genetics 78 (1989), S. 728-734 
    ISSN: 1432-2242
    Keywords: Esterases ; Genetic variability ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Genetic variability of endosperm esterase has been studied in 42 cultivars of Triticum aestivum L. 2n=6x=42. Different techniques, including sequential electrophoresis and electrofocusing, have been used with various substrates and esterase inhibitors. The electrophoretic patterns in each cultivar are described. Chromosomal location using the nullitetrasomic and ditelosomic lines of Chinese Spring was carried out in order to relate and/or locate the esterase genes to specific chromosomes. Most of the esterase isozymes located were in the long arm of the chromosomes of the homoeology group 3; but we have found six located in the short arms, five of them in the chromosome 3AS and one in the 3DS. This location increases the number of esterase genes described, because no esterase genes had been described so far in short arms of chromosomes of the homoeology group 3. The genetic control is discussed and, according to our results, between 12 and 15 loci, organized in five “compound loci”, control the endosperm esterases in wheat. Also one “modifier” gene modifying the mobility of two esterase bands and present in all the cultivars studied is postulated.
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    Theoretical and applied genetics 78 (1989), S. 873-878 
    ISSN: 1432-2242
    Keywords: Heat shock proteins ; 2D electrophoresis ; Triticum aestivum ; Gene location ; Gene regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The low molecular weight heat shock protein (HSP) profiles of the hexaploid wheat cultivar “Chinese Spring” and its ditelosomic series were characterized by isoelectric focusing polyacrylamide gel electrophoresis of denatured in vivo radiolabeled proteins. Comparisons of the ditelosomics (DTs) to the euploid “Chinese Spring” enabled the assignment of genes controlling 9 of the 13 targeted HSPs to seven chromosome arms. There did not appear to be a genome-specific action in the regulation of expression of these HSPs. There did appear to be a higher frequency of controlling genes within homoeologous DT lines 3, 4 and 7. Significant variation in protein quantity was evident among the DT lines for some HSPs, while other HSPs were remarkably stable in their expression across all DTs examined. The results are useful in identifying specific DT lines for the investigation of HSP functions in hexaploid wheat.
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  • 84
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    Theoretical and applied genetics 66 (1983), S. 111-121 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Agropyron ; Intergeneric hybrids ; Embryo culture ; Chromosome pairing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Intergeneric hybrids of Triticum aestivum (2n=42,AABBDD) with Agropyron ciliare (2n= 28,SSYY), A. trachycaulum (2n=28,SSHH), A. yezoense (2n=28,SSYY) and A. scirpeum (2n=28) are reported for the first time. F1 hybrids of T. aestivum were also produced with A. intermedium (2n=42,E1E1E2E2Z1Z1) and A. junceum (2n=14,JuJu). All wheat-Agropyron hybrids were obtained by embryo rescue technique. Cultivars and reciprocal crosses differed for seed set, seed development and F1 plant production. The F1 hybrids were sterile. Attempts to obtain amphiploids were unsuccessful. However, backcross derivatives were obtained with wheat as the recurrent parent. The level of chromosome pairing in A. trachycaulum x wheat, A. yezoense x wheat and wheat x A. junceum hybrids provided no evidence of homologous or homoeologous pairing. Mean pairing frequencies in A. ciliare x wheat, wheat x A. scirpeum and wheat x A. intermedium hybrids indicated homoeologous or autosyndetic pairing. Ph gene was more effective in regulating homoeologous pairing in A. yezoense x wheat hybrids than in A. ciliare x wheat hybrid. Chromosome pairing data of BC1 derivatives indicated that either some of the wheat chromosomes were eliminated or Agropyron chromosomes caused reduced pairing of wheat homologues.
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  • 85
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Gliadins ; Electrophoresis ; Hybridological analysis ; Genetic nomenclature
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary Inheritance of gliadin components in winter wheat has been studied by one-dimensional polyacrylamide gel electrophoresis. Single F2 grains from 36 intervarietal hybrid combinations have been analysed. The genetic analysis has revealed blocks, including 1–6 gliadin components, which are inherited as individual mendelian traits. About 80 variants of blocks have been detected. On the basis of the allelism test they are grouped into 6 series in accordance with the number of known gliadin-coding loci located on chromosomes of the homoeologous groups 1 and 6. Each series includes 8–18 blocks controlled by different alleles of one gliadin-coding locus. Blocks of components have been confirmed to be inherited codominantly in accordance to the gene dose in the triploid endosperm. The highest similarity between members of one series is observed in groups of blocks controlled by chromosomes ID and 6D. On the contrary, many blocks controlled by chromosomes 1A and 1B have no bands in common. The presented catalogue of blocks of components may be used to make up gliadin genetic formulae and to compare electrophoregrams obtained by different authors. Blocks of gliadin components are suitable genetic markers for use in revealing and studying heterogeneity of wheat varieties, in tracing their origin, in identifying recombinations, translocations and substitutions of the genetic material and in solving many other problems of the origin, evolution and selection of hexaploid wheat.
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  • 86
    ISSN: 1432-2242
    Keywords: Amphiplasty ; Ag-NOR ; Addition lines ; Nucleolar organizer ; Agropyron elongatum ; Triticum aestivum
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    Topics: Biology
    Notes: Summary The nucleolar organizer activity of the Agropyron elongatum, its amphiploid with hexaploid wheat (Triticum aestivum) and the chromosome addition lines is analyzed by the silver-staining procedure. Four Ag-NORs are observed in A. elongatum corresponding to the chromosomes 6E and 7E. In the amphiploid T. aestivum — A. elongatum, eight Ag-NORs are observed which corresponds the wheat chromosomes 1B and 6B and to the elongatum chromosomes 6E and 7E. Thus, there is codominance in the nucleolar organizer activity of the chromosomes of the two species. However, a partial amphiplasty is detected since less than 8 Ag-NORs (7 up to 4) are observed in some metaphase cells; the chromosomes 6E and 7E are occasionally suppressed by wheat chromosomes. This conclusion is confirmed by the behaviour of the addition lines since only in those corresponding to the chromosomes 6E and 7E are the elongatum chromosomes nucleolar active although occasionally they can be suppressed by wheat chromosomes.
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    Theoretical and applied genetics 69 (1984), S. 193-198 
    ISSN: 1432-2242
    Keywords: C-banding ; Heterochromatin ; Meiosis ; Common wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The meiotic identification of nine pairs of chromosomes at metaphase I of meiosis of Triticum aestivum (B genome, 4A and 7A) has been achieved using a Giemsa C-banding technique. As a result, the analysis of the pairing of each chromosome arm in disomic and monosomic intervarietal hybrids between ‘Chinese Spring’ and the Spanish cultivar ‘Pané 247’ could be carried out. Differences in the chiasmata frequencies per chromosome arm cannot be explained on the basis of relative arm lengths only. Possible effects of arm-to-arm heterochromatic differences on meiotic pairing are discussed.
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  • 88
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Gliadins ; Two-dimensional electrophoresis ; Hybridological analysis
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary Blocks of gliadin components found both in a number of varieties and in single F2 grains of winter wheat intervarietal hybrids have been studied by two-dimensional electrophoresis combining electrophoresis in acidic aluminium-lactate buffer (pH3.1) and SDS-electrophoresis. Gliadin components (spots) have been shown to be inherited as linked groups (blocks), codominantly and in accordance with a gene dosage in triploid endosperm. Blocks include components differing in their electrophoretic mobility and molecular weight. Some allelic variants of blocks differ only in presence of few additional components or in the electrophoretic mobility of components with similar molecular weights; other variants may contain no similar components. Apparently, in the course of evolution, mutations in individual genes of gliadin-coding loci and processes changing the number of expressing genes and the sizes of their structural part occurred.
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  • 89
    ISSN: 1432-2242
    Keywords: Intrachromosomal mapping ; Nucleolar organiser region ; Triticum aestivum
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    Notes: Summary Restriction enzyme digestion of the ribosomal RNA genes of the nucleolar organisers of wheat has revealed fragment length polymorphisms for the nucleolar organiser on chromosome 1B and the nucleolar organiser on 6B. Variation between genotypes for these regions has also been demonstrated. This variation has been exploited to determine the recombination frequency between the physically defined nucleolar organiser on 1B (designatedNor1) and other markers; two loci,Glu-B1 andGli-B1 which code for endosperm storage proteins andRf3, a locus restoring fertility to male sterility conditioned byT. timopheevi cytoplasm.Gli-B1 andRf3 were located on the short-arm satellite but recombine with the nucleolar organiser giving a gene order ofNor1 — Rf3 — Gli-B1. Glu-B1 is located on the long arm of 1B but shows relatively little recombination withNor1, which is, in physical distance, distal on the short arm. This illustrates the discrepancy between map distance and physical distance on wheat chromosomes due to the distal localisation of chiasmata. The recombination betweenNor1 andRf3 indicates that, contrary to previous suggestions, fertility restoration is not a property of the nucleolar organiser but of a separate locus.
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  • 90
    ISSN: 1432-2242
    Keywords: Line × tester analysis ; Triticum aestivum ; Gene action ; Combining ability ; Mating designs
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary For studying the inheritance of metric traits, diallel cross and factorial mating designs are commonly used. Since factorial mating design is less restrictive in crossing plans, the genetic information drawn from it was compared with that from a diallel cross. The comparison was made using graphical, genetic components and combining ability analyses for grain yield, grain weight and spike length in a field experiment of bread wheat (Triticum aestivum L.). Analyses were made on a nine parent diallel cross and a 4 ♀ × 5 ♂ factorial mating design which was sampled from the diallel cross. In general, there was a high degree of agreement between the results obtained from factorial mating design and diallel cross analyses showing thereby that the former provides almost equivalent genetic information to the latter.
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    Theoretical and applied genetics 69 (1985), S. 583-589 
    ISSN: 1432-2242
    Keywords: Common wheat ; Triticum aestivum ; Electrophoresis ; Endosperm proteins ; Glutenins ; Gliadins ; Genetic control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Total endosperm proteins extracted from both several common wheat cultivars and some intervarietal substitution lines derived from them were fractionated according to their molecular weight in a high resolution one-dimensional gel electrophoresis. The four donor cultivars and the recipient one — ‘Chinese Spring’, possessed differentially migrating protein bands in the fractions of high molecular weight (HMW) glutenins and gliadins. Several of these bands were identified for the first time in this study. By utilizing intervarietal substitution lines the control of the HMW glutenins and gliadins by chromosomes of homoeologous group 1 was either reaffirmed or, for the new bands, established. Several HMW gliadin subunits showed a considerable variation in their staining intensity in the intervarietal substitution lines indicating that their expression was dependent on the genetic background.
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  • 92
    ISSN: 1432-2242
    Keywords: Anther culture ; Pollen callus (plantlet) ; Induction frequency ; Triticum aestivum ; Agropyron glaucum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Experimental results showed that the use of potato extract as a basic component of culture medium had a promoting effect on producing calli in anther culture of the intergeneric hybrids of Triticum aestivum × Triticum-Agropyron (intermediate type). The induction frequencies of pollen callus on the Potato-II medium containing potato extract as the main component was much higher than that found on N6 and W5 media. The induction frequencies of pollen callus and green plantlets in four intergeneric hybrid material inoculated at the late-uninucleate pollen stage were all higher than those inoculated at the mid-uninucleate stage. Appropriate increases in culture temperature significantly increased pollen callus induction frequencies of the intergeneric hybrids. The genotype and physiological state of anther donor plants also influenced pollen callus and green plantlet induction frequencies.
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    Theoretical and applied genetics 70 (1985), S. 634-642 
    ISSN: 1432-2242
    Keywords: Hexaploid wheat ; Triticum aestivum ; Glutenins ; Electrophoresis ; Amino acid analysis ; Peptide mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Several high molecular weight endosperm glutenin subunits, coded by genes located on chromosomes 1A, 1B and 1D of common wheat, Triticum aestivum L. em. Thell., were isolated from excised gel segments and subjected to amino acid analysis and peptide mapping; the latter was carried out following a limited digestion with trypsin, chymotrypsin or Staphylococcus aureus — V8 protease. Generally, all high molecular weight glutenins had a similar amino acid composition but several significant differences were observed in some of them. Both analyses revealed that the structural similarity among the various subunits was related to the homology of the genes coding them: subunits coded by homoalleles, i.e., different alleles of the same gene, were most similar; those coded by homoeoalleles, i.e., alleles of homoeologous genes, were less similar; whereas subunits coded either by alleles of different genes of the same gene cluster, or by nonhomoeoalleles of homoeologous clusters, were the least similar. Several small peptides derived from protease digestion of various subunits had a higher than expected staining intensity indicating that small peptide repeats may be interspersed within the glutenin subunits. The evolutionary course of the high molecular weight glutenins is discussed.
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    Theoretical and applied genetics 71 (1985), S. 278-283 
    ISSN: 1432-2242
    Keywords: Nucleolar competition ; Amphiplasty ; Ag-NORs ; Addition lines ; Triticum aestivum ; Aegilops umbellulata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nucleolar organizer activity of wheat (Triticum aestivum, AABBDD) and Aegilops umbellulata (UU) chromosomes have been analyzed in the complete set of the chromosome addition lines by using a highly reproducible silver-staining procedure. Chromosomes 1U and 5U produce the partial inactivation of wheat nucleolar organizer chromosomes 6B, 1B and 5D. The chromosomes D and G from Ae. umbellulata, which are not SAT-chromosomes, seem to specifically influence the activity of wheat NORs. The predominant status of the U genome with respect to nucleolar competition in the Triticeae is confirmed.
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  • 95
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Agropyron caninum ; Elymus caninus ; Intergeneric hybrids ; Chromosome pairing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Intergeneric hybrids were produced between common wheat, Triticum aestivum (2n=6x=42, AABBDD) and wheatgrass, Etymus caninus (Agropyron caninum) (2n=4x=28, SSHH) — the first successful report of this cross. Reciprocal crosses and genotypes differed for percent seed set, seed development and F1 hybrid plant production. With E. caninus as the pollen parent, there was no hybrid seed set. In the reciprocal cross, seed set was 23.1–25.4% depending upon wheat genotype used. Hybrid plants were produced only by rescuing embryos 12–13 days post pollination with cv ‘Chinese Spring’ as the wheat parent. Kinetin in the medium facilitated embryo germination but inhibited root development and seedling growth. The hybrids were vigorous, self sterile, and intermediate between parents. These had expected chromosome number (2n=5x=35, ABDSH), very little chromosome pairing (0.51 II, 0.04 III) and some secondary associations. The hybrids were successfully backcrossed with wheat. Chromosome number in the BC1 derivatives varied 54–58 with 56 as the modal class. The BC1 derivatives showed unusually high number of rod bivalents or reduced pairing of wheat homologues. These were sterile and BC2 seed was produced using wheat pollen.
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  • 96
    ISSN: 1432-2242
    Keywords: Tissue culture ; Electrophoresis ; Storage proteins ; Mutation ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Fertile r0 plants of the winter wheat line ND7532 (Triticum aestivum L.) were regenerated from callus tissue after 60–190 days in culture. Seeds produced from these self-pollinated plants were planted in the field. Of the 5586 R1 plants, 32 differed for one or more agronomic traits from plants not passed through tissue culture process. Gliadin electrophoregrams were prepared from bulk samples of R2 seed from these 32 plants. Four of the 32 produced gliadin patterns different from controls, so 12 seeds of each of these four lines were examined individually. Three of the four mutant lines were fixed for the presence of a mutant protein of 50 relative mobility units (RMU) and the corresponding loss of a parental protein of 26 RMU. The remaining line segregated for the presence/absence of band 50 and the corresponding loss/retention of band 26. The mutant protein of 50 RMU was never seen in control plants. This indicated that either band 50 was coded for by a mutant gene allelic to the gene that coded for band 26 or that bands 26 and 50 were coded for by two different structural alleles under the control of a common regulatory locus. Each of the 12 seeds from the four mutant lines contained a prominent protein band at 30 (RMU), which was only observed as a faint band in one control seed. The types of variation in gliadin patterns observed in somaclones of ND7532 were similar to those reported for the line ‘Yaqui 50E’, except that, gliadin changes occurred less frequently in ND7532.
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  • 97
    ISSN: 1432-2242
    Keywords: Mitochondrial DNA of plants ; Electron microscopy ; Suspension culture ; Vicia faba
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A comparative analysis of the Vicia faba mitochondrial genome in whole plants and in longterm suspension culture has been conducted. Restriction fragment patterns of the mtDNA isolated from these two sources were notably different. Electronmicroscopic analysis also revealed significant differences. Large circular mtDNA patterns shifted from a 37–80 kb subpopulation, which was predominant in whole plants, to 18–34 kb subpopulations although in both classes notable quantities of circular molecules of 80 to 120 kb and more were also found. Both in whole plant and suspension culture cells very large circular DNAs were observed. Some of them had lengths nearly 290 kb and could be considered as evidence of the existence of master chromosomes. The minicircular DNA population was also altered. In the suspension culture we observed a notable increase of percentage of minicircles with sizes near 1 kb. Simultaneously, the percentage of minicircles with sizes near 3.5–10 kb significantly increased in suspension culture cells. In addition, a new peak (10–12 kb) of minicircles appeared. Copy number alterations for some sequences homologous to CCC1A, CCC1B and CCC2 (Negruk et al. 1982, 1985) were shown. Southern hybridization revealed the existence of a family of minicircles having sizes 1.4–2 kb with predominance of CCC1A, CCC1B and CCC2. The copy numbers of CCC1B and some minor minicircles was changed in the suspension culture when compared with the whole plants.
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  • 98
    Electronic Resource
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    Theoretical and applied genetics 72 (1986), S. 548-550 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Monosomic analysis ; Inheritance ; Gene location
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The inheritance of yellow berry, a grain disorder in durum and bread wheats, was studied in six intervarietal crosses in bread wheat. The trait was found to be controlled by either two or three dominant genes. Monosomic analysis using ‘Chinese Spring’ monosomic series showed the presence of two major dominant genes on chromosomes 1A and 7A, and four modifiers on 4A, 4B, 6A and 6D, which influence the expression of yellow berry in bread wheat.
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  • 99
    ISSN: 1432-2242
    Keywords: Common wheat ; Triticum aestivum ; Structural rearrangements ; Translocation ; Interchange ; Duplication-deficiency ; Aneuploidy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The winter wheat varieties ‘Starke’ and ‘Cappelle Desprez’ and the spring wheat ‘Chinese Spring’ were analysed for structural chromosome rearrangements that resulted in the formation of multivalents in F1 hybrids. The analyses were carried out using hybrids involving euploids, monosomic and ditelosomic stocks, and double-monotelodisomic constructs. The study confirmed that ‘Cappelle Desprez’ differs from ‘Chinese Spring’ in a reciprocal translocation between chromosomes 5B and 7B (Riley et al. 1967); a translocation involving chromosomes 3B and 3D could not be verified. Furthermore, the analysis showed that ‘Starke’ differs from ‘Chinese Spring’ in a reciprocal translocation between chromosomes 7A and 7D. Both translocations have a coefficient of multivalent realisation of about 0.84. Further multivalents in euploid ‘Starke’, in euploid and some aneuploid stocks of ‘Cappelle Desprez’, and in euploid as well as various types of aneuploid hybrids between all three varieties could nearly all be explained hypothesizing that chromosome 2B of both ‘Starke’ and ‘Cappelle Desprez’ is a duplication-deficiency chromosome. In the hypothesis a part of the long arm of 2B is missing and replaced by a duplicated part of the long arm of chromosome 2D. The multivalents of this rearrangement showed an average coefficient of realisation of about 0.09.
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  • 100
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 65 (1983), S. 41-46 
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Wheat ; Protein ; Mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Poor adaptability or functional quality of much germplasm used for breeding high-protein hard red winter wheats prompted mutagenesis as an alternative means of increasing grain protein content. Four hard red winter wheat genotypes — KS644 (‘Triumph// Concho/Triumph’), ‘Kaw’, ‘Parker’, and ‘Shawnee’ — were treated with 0.40 M ethyl methanesulfonate (EMS). Advanced lines (M8-M10) were selected that had a 3-year mean grain protein advantage of 0.7% to 2.0% over controls. Increased grain protein content was generally associated with decreased grain yield and kernel weight, but some high-protein mutant lines had yields or kernel weights similar to those of original genotypes. Changes in height and lodging induced by EMS were generally favorable, most mutants being shorter and lodging less than controls, but blooming date was generally delayed, a deleterious change. One line also changed from resistant to segregating for wheat soil-borne mosaic virus. Mutant lines might be utilized in cross-breeding programs, particularly if negative pleiotropic effects and linkages are absent.
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