bluuebunny/crossref_metadata_2025 huggingface dataset:
Promotion of plant growth and inhibition of enzymic degradation of indole-3-acetic acid by metabolites of carbofuran, a carbamate insecticide
Authors: Lee T. T.
Published: September 2008

The carbamate insecticide carbofuran (2,2-dimethyl-2,3-dihydrobenzofuranyl-7-N-methyl carbamate) and three of its metabolites (7-hydroxy-2,2-dimethyl-2,3-dihydrobenzofuran (III), 3,7-dihydroxy-2,2-dimethyl-2,3-dihydrobenzofuran (IV), and 3-keto-7-hydroxy-2,2-dimethyl-2,3-dihydrobenzofuran (V)) stimulated growth in the pea stem segment assay in the presence, but not absence, of a low concentration of indole-3-acetic acid (IAA). The metabolites were more active than carbofuran itself. The synergistic effect on growth was specific with IAA since it was not observed in the presence of other auxins.Metabolites III, IV, and V and, to a lesser degree, carbofuran were found to be inhibitory to IAA degradation catalyzed by pea stem tissue or purified horseradish peroxidase (EC 1.11.1.7). Comparison of the relative activities of the compounds in the inhibition of IAA degradation and in the promotion of plant growth suggests a causal relationship. The implication is that carbofuran may promote plant growth through the inhibitory action of its metabolites on enzymic breakdown of IAA, thus preserving a critical level of IAA required for growth promotion.
Ultrastructure of conidiogenesis in the thallic Hyphomycete Oidiodendron griseum
Authors: Terracina Fred C.
Published: September 2008

Electron microscopy of conidiogenesis in the thallic Hyphomycete Oidiodendron griseum Robak was done on material fixed in glutaraldehyde followed by OsO4. Endohyphae are found at the base of the stalk-like conidiophore. Arthroconidia are formed by basipetal and random septation of the preformed apical fertile hyphae. The thickening of these septa gives the appearance of connectives between adjacent arthroconidia.
Nitrogen fixation by Stereocaulon paschale under field conditions
Authors: Huss-Danell Kerstin
Published: September 2008

Nitrogen fixation (C2H2 reduction) by the lichen Stereocaulon paschale (L.) Fr. was studied in the field in northern Sweden. Field studies were carried out in a very dry dwarf-shrub-type pine forest with S. paschale as the only nitrogen-fixing lichen species. During May–September 1973 and 1974 nitrogen fixation was measured on 28 occasions at irregular intervals, and a total of about 1200 lichen samples were studied. The mean nitrogen-fixation activity during May–September was 0.85 and 1.04 μg N g−1 dry weight h−1 for 1973 and 1974 respectively. The water content of the thallus was the most important factor influencing the nitrogen-fixation activity. Studies on gain and loss of thallus water served as a basis for calculating the number of hours when nitrogen fixation occurred. In the area investigated, with S. paschale covering 14% of the ground, the species was calculated to contribute 0.1 g nitrogen fixed per square metre during May–September 1974.
Experimental studies on the shoot apex of Helianthus annuus: the effect of surgical bisection on quiescent cells in the apex
Authors: Davis E. L. , Steeves T. A.
Published: September 2008

When the shoot apex of Helianthus annuus cv. Peredovic is bisected surgically, two new apices are regenerated, each of which, 3 weeks after the operation, contains a quiescent central zone similar to that of the original apex. The operation destroys some cells of the original zone and stimulates others to become active in DNA synthesis. Regenerating apices, supplied with [H3] thymidine and autoradiographed at the end of the 2nd day after the operation, reveal no evidence of a quiescent zone. Evidence for the establishment of quiescence appears by the end of the 3rd day and becomes clearer on the 4th and 5th days after the operation. There is no evidence that the residual zone cells play any particular role in regeneration. It is suggested that quiescence in regard to DNA synthesis and mitosis appears sooner than the cytological features associated with quiescence in the sunflower shoot apex.
Note on lack of effect of ethylene on water permeability, electroosmotic efficiency, or transcellular water flow of the plasma membranes in Nitella
Authors: Fensom D. S. , Ross S. M.
Published: September 2008

Ethylene (4.0 mM) in artificial pond water had no significant effect on three permeation properties of the plasma membranes of Nitella 2 h after addition. Neither the hydraulic permeability measured by transcellular osmosis, the passive monovalent cation permeability measured by electroosmosis, nor the 'active' transcellular water flows were altered appreciably by ethylene in solution.
Effect of a morphactin on growth, sex expression, fruit-set, and yield in Luffa acutangula
Authors: Bisaria A. K.
Published: September 2008

A single foliar spray of a morphactin (n-butyl-9-hydroxyfluorene-(9)-carboxylate) was applied at a concentration of 1, 10, 100, or 1000 ppm to 6-week-old plants of ribbed gourd (Luffa acutangula Roxb.), a monoecious cultivar, Pusa Nasdar. Growth of the main axis was only stimulated at 1 ppm and was increasingly inhibited at higher concentrations. Morphactin weakened apical dominance and increased the number of lateral branches. The production of pistillate and staminate flowers was increased and then decreased by morphactin, up to a concentration of 100 ppm. At the same concentrations it also increased femaleness, number of fruits, and therefore the yield. A drastic inhibition of total flowering, fruit-set, and therefore yield was recorded at 1000 ppm. Parthenocarpic fruits developed only at 100 and 1000 ppm.
The ultrastructure of conidium ontogeny in Pestalotiopsis neglecta
Authors: Jones John P.
Published: September 2008

Electron microscopy has been used to study conidium ontogeny of Pestalotiopsis neglecta, an annellidic coelomycete, to compare it with previously studied phialidic fungi. It was found that phialidic fungi produce a multiplicity of conidia from a fixed conidiogenous locus within the conidiophore, but annellidic fungi produce conidia individually from progressively different, usually higher, loci within the conidiophore. With the exception of the primary phialidic conidium, both types of organism produce conidia enteroblastically.
On the fine structure of differentiating mucilage papillae of Marchantia
Authors: Galatis B. , Apostolakos P.
Published: September 2008

In Marchantia, the mucilage papillae are initiated by differential divisions occurring in marginal cells of scales at early stages of their development. Establishment of a new polarity axis was observed in mucilage papilla mother cells as well as in their daughter cells, which were destined to develop into mucilage papillae. During polarization the marginal cells synthesize cytoplasm and free ribosomes; subsequently, the cells grow outwards. Concomitantly, organelles migrate to the apical region, where some rough endoplasmic reticulum (ER) membranes and dictyosomes are polarly placed. The subplasmalemmal microtubules become reoriented during polarization.The spindle-shaped preprophase and prophase nucleus of the mucilage papilla mother cell is surrounded by two distinct microtubular systems: the preprophase band of microtubules and an extranuclear sheath of microtubules; the latter is aligned along the spindle axis, close to the nuclear membrane and convergent at polar areas which contain ER membranes.Among the first structural signs of mucilage papillae differentiation are the following: increase of cytoplasm, free ribosomes, rough ER membranes, and dictyosomes; preferential association of plastids with ER membranes and mitochondria, as well as the transverse orientation of subplasmalemmal microtubules. As differentiation ensues the cells acquire more cytoplasm and their organelles proliferate markedly, while new specific organelle relationships become evident.The increase of rough ER membranes predominates and keeps pace with dictyosome proliferation. Among the organelles the ER membranes display a key role in diverse mucilage papilla differentiation and an intermediary one in their secretory activity.The particularly active secretory phase of mucilage papillae is marked by an hypersecretory activity of dictyosomes which produce abundant vesicles. Histochemical staining revealed polysaccharides in the larger vesicles, the space between plasmalemma and cell wall, and within the wall.Ultimately, the mucilage papillae either undergo a partial degradation of protoplasm or even degenerate. In the former case they undergo an intense vacuolation and finally appear structurally similar to other cells of scales.
Photosynthesis and light and dark respiration in freshwater algae
Authors: Bidwell R. G. S.
Published: September 2008

Rates of gas exchange were measured for cultures of Chlorella pyrenoidosa, Chlamydomonas reinhardtii, and Anabaena flos-aquae, which were suspended in moist air on an artificial leaf made with nylon bolting cloth. A 14CO2–12CO2 technique was used to measure net and gross photosynthesis and light and dark respiration in air or nitrogen. Rates of gas exchange on the artificial leaf were equal to maximum rates obtainable for the same algae suspended in culture medium. Rates were stable, and the artificial leaf could be maintained for many hours.The algae did not exhibit conventional photorespiration. However, they did have a variable rate of light respiration that frequently equalled, but did not exceed, the rate of dark respiration. This light respiration appeared to be a continuation of normal dark respiration in light. It was affected by CO2 concentration, declining to zero if the cells were illuminated in the absence of CO2. Unlike higher plants, recent photosynthate is not a substrate of light respiration in these algae.
Nematophagous fungi: Protascus and its relationship to Myzocytium
Authors: Barron G. L.
Published: September 2008

Evidence is presented to support the transfer of Protascus subuliformis to Myzocytium. Based on the nature of the sporangiospores and the method of attacking the host, the known species of Myzocytium parasitic on nematodes are divided into five series. The major characteristics and possible biological advantages of each of these series are outlined. A key to the species of nematophagous Myzocytium species is included.
Controlling soil water matric potential in root disease studies
Authors: Wisbey B. D. , Black T. A. , Copeman R. J.
Published: September 2008

Soil contained in 5.6 × 2.0 × 10.5 cm Plexiglas soil containers was separated from solutions of polyethylene glycol (PEG) 6000 by a Pellicon ultrafiltration membrane glued over the inside of 3.8-cm-diameter holes in two sides. Flow rate through the membrane was 4.4 ml day−1 cm−2 for a 1.0-bar potential difference across the membrane. At the end of 2 weeks, the average matric potential in the soil adjacent to the membranes for soil cells immersed in −0.2-, −1.0-, and −2.0-bar PEG solutions was −0.3, −1.1, and −2.3 bars respectively. The relatively constant potential and vigorous plant growth during the period indicated that sufficient water was passing through the membrane to meet the plant's water requirements. The Pellicon membrane's tolerance to microbial deterioration will permit the use of this technique in longer term studies than previously has been possible.
Effect of cyclic AMP on catabolite-repressed zoosporangial formation in Phytophthora capsici
Authors: Yoshikawa M. , Masago H.
Published: September 2008

Zoosporangial formation in Phytophthora capsici was sensitively inhibited by glucose and other catabolites including sugars, citric acid cycle acids, and amino acids, but was only slightly inhibited by 3-O-methylglucose and 2-deoxyglucose and by other seemingly weak catabolites. The inhibitions were specifically prevented by cyclic AMP among the various related nucleotides evaluated. The reversing effect by cyclic AMP was observed only on zoosporangial formation that was partially repressed by catabolites, but the completely repressed zoosporangial formation could not be reversed by cyclic AMP. Furthermore, cyclic AMP failed in reversing zoosporangial formation that was inhibited by antibiotics such as antimycin A and cycloheximide. The results suggested that the initiation of zoosporangial formation in the fungus is under the control of catabolite repression that is mediated by cyclic AMP.
Synchronized zoosporangial formation in liquid culture of Phytophthora capsici
Authors: Yoshikawa M. , Nishida A. , Masago H.
Published: September 2008

A method was developed which permitted synchronous zoosporangial formation in Phytophthora capsici. Encysted zoospores were vegetatively grown in liquid medium based on asparagine–glucose for various periods of time under shaking or standing conditions. The resulting young and uniform hyphae were transferred into either deionized water or potassium phosphate buffer (20 mM, pH 6.0) to induce zoosporangial formation. The duration of the vegetative growth phase critically affected the synchrony of the subsequent zoosporangial formation. The optimal periods were 8 to 15 h and 15 to 24 h under shaking and standing conditions, respectively. Under these optimal periods of the vegetative growth, most (>80%) zoosporangia formed between 16and 24 h in both shaking and standing conditions after the transfer. Zoosporangia thus produced were apparently normal in their morphology and ability to germinate.
Modifying the growth habit of the filamentous fungus Fusarium solani to facilitate replica plating procedures
Authors: VanEtten Hans D. , Kølmark H. Gunnar
Published: September 2008

The surfactants Triton X-100 and X-171 were found to facilitate the replica plating of Fusarium solani by markedly inhibiting the radial growth of this fast-growing fungus. In addition, specific types of morphological mutants were isolated which assisted the replica plating of F. solani.
Composition of epicuticular waxes of some grasses
Authors: Tulloch A. P. , Hoffman L. L.
Published: September 2008

The compositions of the epicuticular waxes of grasses Agropyron desertorum, Bromus inermis, Elymus cinereus, Elymus junceus, Festuca ovina, and Phleum pratense have been determined. Hexacosanol was the principal component of wax of A. desertorum and P. pratense, and octacosanol, of wax of E. junceus; C40–C60 esters were major components of wax of B. inermis. Hentriacontane-14, 16-dione and the 25-hydroxy derivative were the principal components of wax of E. cinereus, and the major constituent of wax of F. ovina was tritriacontane-12, 14-dione. The two β-diketone-containing grasses were glaucous.
A new method for measurement of hydraulic conductivity and elastic coefficients in higher plant cells using an external force
Authors: Ferrier J. M. , Dainty J.
Published: September 2008

A small external force is used to produce deformation of the cells and an increase in internal hydrostatic pressure in onion epidermis cells. The subsequent change in cell layer thickness is measured as a function of time. The theory is developed to show that, for sufficiently small forces, this measurement provides enough information to determine cell membrane hydraulic conductivity and elastic modulus, and some results are given. This method should be applicable to sections containing several layers of cells from other kinds of higher plant tissue.
Effects of 15% CO2 on the accumulation of the phytoalexin phaseollin in Phaseolus vulgaris in response to mechanical injury and to infection by Colletotrichum lindemuthianum
Authors: Arnold Robert M. , Rahe James E.
Published: September 2008

Accumulation of phaseollin at sites of point-freezing injury on etiolated hypocotyls of Phaseolus vulgaris occurred in air but was prevented when seedlings were placed in air containing 15% CO2 immediately after injury. The inhibitory effect was partially overcome when CO2-treated seedlings were returned to air. Phaseollin accumulation in 15% CO2 did occur, however, when injured seedlings were maintained in air for 3–9 h before being transferred to CO2, indicating that the sensitivity to CO2 lies at an early stage of the process leading to phaseollin production. In contrast, phaseollin accumulation at sites of infection of P. vulgaris by an incompatible race of Colletotrichum lindemuthianum was not inhibited by 15% CO2. These results indicate that the processes leading to the accumulation of phaseollin at incompatible infection sites and at injury sites may be regulated differently.
Pezizella chapmanii n.sp., a discomycete associated with bark beetle galleries in western conifers
Authors: Whitney H. S. , Funk A.
Published: September 2008

Pezizella chapmanii n.sp. (Helotiales) is described from apothecia found in the galleries of various bark beetles in conifers of western Canada; viz., Dendroctonus rufipennis Kirby galleries in Picea glauca (Moench) Voss; D. ponderosae Hopkins galleries in Pinus contorta var. latifolia Engelmann and in P. ponderosa Laws.; D. murrayanae Hopkins galleries in P. contorta var. latifolia; and D. pseudotsugae Hopkins galleries in Pseudotsuga menziesii (Mirb.) Franco. In agar culture, a prominent Malbranchea conidial state is produced.
Nematophagous fungi: a new Harposporium parasitic on Prismatolaimus
Authors: Barron G. L.
Published: September 2008

Harposporium rhynchosporum is described as a new species recovered from farmyard soil. The fungus was found parasitizing only one nematode species belonging to the genus Prismatolaimus. In H. rhynchosporum the phialospores are asymmetrically heart-shaped with a spiny outgrowth to one side of their convex surface. The species is related to H. diceraeum and H. bysmatosporum and the infection cycle is probably initiated by the conidia lodging in the buccal cavity or oesophagus of the host.
Conditions affecting in vivo nitrate reductase activity in chlorophyllous tissues
Authors: Jones Richard Wyn , Sheard Robert W.
Published: September 2008

Nitrite production during darkness by vacuum-infiltrated strips of foliar material was investigated in 6-day-old corn, field peas, wheat, barley, and marrow and in 10-week-old Gomphrena globosa. Inclusion of n-propanol enhanced nitrite production by 10 to 40%, at a species-specific optimum concentration of 0.5 to 1.0% v/v, in all plants except Gomphrena. Triton X-100 (0.1% v/v) caused additional enhancement in corn only. Substantial nitrite production (59 to 94% of maximum) occurred in plants grown with moderate (5 mM) and high (20 mM) nitrate concentrations without exogenous assay nitrate; optimum exogenous nitrate concentration was 50 to 100 mM. The patterns of response towards nitrate and propanol were highly species specific. In contrast, all species responded analogously to pH of the incubating medium, yielding a maximum plateau of activity at pH 7 to 8. Nitrite production was not enhanced by substitution of nitrogen for air during vacuum infiltration and incubation. Assay conditions yielding maximum rates of nitrite production were not affected by growth conditions which yielded higher in vivo activity at high vs. low irradiance and at high vs. low nutrient nitrate. Plants grown with moderate irradiance and nitrate exhibited 1.2- to 6-fold higher in vitro than in vivo nitrate reductase (EC 1.6.6.1) activities. In plants grown at high irradiance and low nutrient nitrate, in vivo nitrite production without exogenous nitrate was severely limited by in situ nitrate, indicating that nitrate reduction can be regulated by the rate of supply of substrate to foliar tissues under certain conditions.
Cell growth, wall deposition, and correlated fine structure of colchicine-treated lettuce hypocotyl cells
Authors: Srivastava L. M. , Sawhney V. K. , Bonettemaker M.
Published: September 2008

The effects of colchicine, singly and in combination with gibberellic acid (GA3), on growth of lettuce hypocotyl cells are reported. After 72 h of growth, the cells in GA3 are extremely long and cylindrical, whereas those in GA3 + colchicine are very large and more or less isodiametric. The cell volume in colchicine is not significantly different from that in the water control. Kinetic data on cell growth and on dry weight of cell walls indicate a parallelism between the GA3 and GA3 + colchicine treatments and between the colchicine treatment and water control. In all treatments, certain cytological changes, viz. proliferation of dictyosomes and their vesicles, increase in endoplasmic reticulum (ER) and polyribosomes, and increased connections between the ER and plasmalemma, occur at the same time as in the water conrol and proceed ahead of evident cell growth. Changes in wall fibrils and microtubules are described. It is concluded that colchicine does not inhibit the kinetics of cell growth or the deposition of wall material, but since it causes dissolution of microtubules, the deposition of new wall fibrils is random even though it shows some degree of order, and if at that time the cells are growing rapidly under the influence of GA3, they become spherical. These results are discussed with a view to understanding the mechanisms underlying cell enlargement.
Adhesion of the Boston ivy tendril
Authors: Endress Anton G. , Thomson William W.
Published: September 2008

Tactile stimulation of Boston ivy tendrils results in the development of bilaterally symmetric discs which adhere to substrates in the vicinity of the tendrils. Our electron microscopic examination of the tendrils indicates that adhesive secretion occurs from the peripheral cells at the contact face of the discs. Cell walls in this region develop pockets which fill with adhesive and ultimately coalesce. In fully adherent discs, the adhesive occupies the region between the substrate and the cells as well as the intracellular regions between the peripheral cells. While a cuticle was present on immature discs, no cuticle-like material was observed at the contact interface of mature discs.Staining of the adhesive was enhanced by ruthenium red and potassium ferrocyanide treatments, and the adhesive bound both colloidal iron and thorium. These results indicated that the adhesive is possibly a mucopolysaccharide.
Defect development in second-growth sugar maple in Ontario. I. Microfloral infection relationships associated with dead branches
Authors: Basham J. T. , Anderson H. W.
Published: September 2008

From 293 second-growth sugar maple (Acer saccharum Marsh.) trees (maximum age 114 years) felled in Ontario, 966 branch stubs, 70 intact dead branches, and 58 stem stubs were dissected and studied. Microfloral associations, examined and related to many tree and wound characteristics with computer assistance, show a progressive pattern of invasion, spread, colonization, and replacement within dead branches, stubs, and adjacent stem wood tissue. A unique, limited fungal microflora colonizes dead branches and one of these fungi, Nodulisporium sp. 5, appears instrumental in the early self-pruning habit of sugar maple. All but 25 of the 80 organisms or organism groups isolated from stubs occurred rarely, and these were mainly near the exposed stub ends. Most organisms seem incapable of prolonged existence there, or of much penetration into the stub. Most stub fungi lose viability once the stubs are healed over, particularly those associated with decay pockets near the exposed ends. These include the two most frequently isolated fungi, Rhinocladiella sp. A and Stachybotrys atra Corda, whose occurrence in sugar maple trees is virtually limited to branch stubs. Only bacteria and four of the fungi that invade branch stubs appeared capable of appreciable spread and development after complete stub healing; these organisms generally dominate the resident microflora encountered in the stained core of living sugar maple trees. Evidence indicates that the stain present in many of the stubs, often extending into the main stem, is principally physiological in origin, but its development is enhanced by the presence of certain microorganisms. Decay was far less common, seldom reaching the main stem; evidence suggests most stub decay is caused by Corticium vellereum Ell. & Cragin, a Basidiomycete isolated from, but reportedly incapable of causing, stem decay in mature maple.
A new nematode-trapping hyphomycete and a reevaluation of Dactylaria and Arthrobotrys
Authors: Schenck S. , Kendrick W. B. , Pramer D.
Published: September 2008

The discovery of a new nematode-trapping hyphomycete producing ameroconidia but clearly assignable to the otherwise didymoconidial form-genus Arthrobotrys leads to a reevaluation of generic concepts in Arthrobotrys Corda and Dactylaria Sacc. The nematode-trapping species of Dactylaria are transferred to Arthrobotrys.
Dicranum ontariense Peterson: a new name for a North American endemic moss
Authors: Peterson Wilbur
Published: September 2008

Because of nomenclatural confusion, a North American endemic moss species and a distinctly different Eurasian species have both been referred to as Dicranum drummondii C. Mueller. Evidence is presented to indicate that this name should be applied to the Eurasian species and not the North American one as is commonly done. This leaves the North American species without a name. Dicranum ontariense is proposed as the new name and a description and distribution map are given.
Vegetative bud development and cone differentiation in Abies amabilis
Authors: Owens John N. , Molder Marje
Published: September 2008

In the trees studied, vegetative buds began development in early April, bud burst occurred in early June and shoot elongation was completed by late July. Vegetative buds initiated bud scales from mid-April until mid-July and then initiated leaf primordia until the vegetative buds became dormant in November. All axillary buds were initiated in mid-May and their bud scales were initiated until early July. During bud-scale initiation, distal vegetative lateral apices were more conical but had a mitotic frequency similar to other lateral apices. Near the end of bud-scale initiation, vegetative apices accumulated more phenolic and ergastic compounds in future pith cells than did potential seed-cone or pollen-cone apices. Bud differentiation occurred in mid-July at the end of lateral shoot elongation. During bud differentiation the mitotic frequency of pollen-cone and seed-cone apices increased much more than that of distal vegetative apices. This resulted in a marked increase in apical size and a change in apical shape and zonation that made reproductive apices easily distinguishable from vegetative apices. Bracts began to be initiated in mid-July, and ovuliferous scales, in mid-August. Both continued to be initiated until seed-cone buds became dormant in November. A single megaspore mother cell formed in each ovule before dormancy. Microsporophylls were initiated from mid-July until early September. Microsporangia began to differentiate in September and contained microspore mother cells when pollen cones became dormant in mid-October. Meiosis did not begin before dormancy. A few potential vegetative and many potential seed-cone and potential pollen-cone apices became latent during bud-scale initiation. Some potential seed-cone apices became vegetative buds. Consequently, the number of cone buds formed was determined primarily by the proportion of apices that developed fully and the pathway along which they developed.
Variations qualitatives et quantitatives des carbures terpéniques au cours de la croissance des rameaux et des aiguilles du Pin maritime: étude comparée de huit phénotypes
Authors: Zimmermann-Fillon C. , Bernard-Dagan C.
Published: September 2008

The variations of the monoterpene and sesquiterpene hydrocarbons have been studied during the growth of the needles and shoots of eight trees of maritime pine. These trees represent the eight possible phenotypic associations for 3-carene, myrcene and limonene. The 'monoterpene profiles' under genetic control are very comparable for a same individual but the differences between phenotypes are more important in oils from cortical tissues than in those from leaves mainly for the 3-carene content.α- and β-Pinene are synthetized very early in the three kinds of organs and tissues studied; needles, wood, and cortical tissues of young shoots. On the contrary, 3-carene, myrcene, and limonene are mainly elaborated in the needles and cortical tissues. The synthesis of limonene and myrcene starts later than that of pinenes and 3-carene. The sesquiterpenes are mainly elaborated in the needles and their accumulation is progressive.These variations during the growth of the organs suggest the existence of several paths for the synthesis of C10 and C15 hydrocarbons.
Observations on the pathology of seaweeds in the Pacific Northwest
Authors: Andrews John H.
Published: September 2008

Seaweeds that displayed disease symptoms were collected intertidally and subtidally from coastal Washington and British Columbia. A red rot of Fucus, characterized by the progressive reddish discoloration and ultimate disintegration of host tissue, was observed frequently. The fungus Cephalosporium was isolated consistently from diseased plants. Extensive galls, from 1 to 50 mm in size, on stipes of Laminaria, Nereocystis, and Macrocystis, were associated invariably with a filamentous, endophytic, and presumably parasitic Streblonema-like alga. A bacterium, identified tentatively as Acinetobacter, was isolated from infected Nereocystis in the laboratory and shown to be pathogenic by fulfillment of Koch's Postulates. Symptoms or signs of this white rot disease were restricted to exposed, floating stipes and pneumatocysts which collapsed, became flaccid, and were covered with a white bacterial slime. Attempts to demonstrate causality with the putative pathogens causing red rot and galls, respectively, were unsuccessful. Nematodes of the genera Paralinhomeous and Monhystera were isolated from Fucus and Laminaria, respectively, but appear to be free-living and not parasitic.
Properties of the single protein and two nucleic acids of tomato ring-spot virus
Authors: Allen Wayne R. , Dias H. F.
Published: September 2008

Purified preparations of several isolates of tomato ring-spot virus were shown by rate-zonal centrifugation in sucrose and equilibrium centrifugation in CsCl to be composed of two individual nucleoprotein components. Acrylamide-gel electrophoresis showed that the lighter (middle) component contained a nucleic acid (RNA 2) that was distinct from the species (RNA 1) contained in the heavier (bottom) component. The bottom was more infectious than the middle component and infectivity was enhanced by mixing the components, indicating that the virus genome is divided between component types. Similar results were obtained from infectivity tests on the two nucleic acids. The nucleic acid contents of the middle and bottom components were about 40 and 41%, respectively. The average molecular weights of RNA 2 and RNA 1 from three virus isolates, as determined by acrylamide-gel electrophoresis, were 2.5 and 2.6 × 106, respectively. Molecular complexing between the RNA species during electrophoresis was prevented with the use of formamide. The single protein subunit from the same three isolates had an average molecular weight of about 58 000. Serological comparisons of five tomato ring-spot isolates associated with diseases of fruit trees and grapevines indicated that only the grape yellow vein strain was antigenically distinct. These and other properties indicate that this virus is similar to other members of the nepovirus group.
Notes on Rosellinia buxi and conidial Xylaria
Authors: Rogers Jack D. , Malmgren Marlene M.
Published: September 2008

Ascus cytoplasm of Rosellinia buxi is convoluted with broad areas containing nuclei separated by isthmus-like connections. Ascospores are formed singly or in pairs in broad areas. Ascospores are at first uninucleate, becoming binucleate via mitosis. Maturing ascospores are uninucleate after disintegration of one of their two nuclei. Aspects of the conidial state are illustrated.The flabelliform conidial state of a Xylaria species, probably X. castorea, is illustrated and discussed.
Fine structure of basidiospores of the cedar-apple rust fungus Gymnosporangium juniperi-virginianae
Authors: Mims Charles W.
Published: September 2008

Each basidiospore of Gymnosporangium juniperi-virginianae contains many ribosomes as well as lipid droplets, mitochondria, small vesicles, endoplasmic reticula, and structures thought to be microbodies. Mature spores are either uninucleate or binucleate although larger, tetranucleate spores were occasionally observed. The spore wall appears as a thin layer except around the hilar region where two layers are evident. Germination is almost always lateral although no germ pore region was noted in the wall. Vacuolation takes place during germination and lipid bodies disappear. The wall of the germ tube arising from the spore is continuous with that of the spore. A large number of vesicles is present in the germ tube. Basidiospores may also germinate by repetition.
Assimilate distribution patterns and carbohydrate concentration changes in organs of Solidago canadensis during an annual developmental cycle
Authors: Bradbury Ian K. , Hofstra G.
Published: September 2008

At different stages in the growth cycle the short-term translocation pattern of 14C-labelled assimilates was determined together with carbohydrate concentration changes in two Solidago canadensis L. populations growing on abandoned pasture sites in southern Ontario. Tagging whole shoots with 14C revealed that (1) a high (50–70%) proportion of assimilated carbon is retained by leaf tissue, (2) the proportion of assimilated carbon incorporated in the aerial stem increases during shoot extension but declines later during inflorescence development, (3) the proportion of assimilated carbon translocated to the inflorescence during flowering and fruiting is considerably in excess of its dry weight contribution, and (4) underground tissues, even the new rhizomes which develop in late season, account for a comparatively small proportion of assimilated carbon. Tagging individual leaves with 14C during reproductive development showed that the proportion of leaves exporting assimilates to the new rhizome system progressively increases, while that supplying the inflorescence decreases, after August and that individual leaves do not simultaneously export carbon to the inflorescence and new rhizomes. Carbohydrate analysis showed that early shoot development is associated with a marked reduction in carbohydrate status of both roots and rhizomes, which is subsequently restored, and that roots and rhizomes retain a storage function for at least 2 and 3 years, respectively.
Characterization of augmented potassium uptake in the seedling primary root of inbred maize (Zea mays)
Authors: Frick Hugh , Nicholson Ralph L. , Bauman Loyal F.
Published: September 2008

As the seedling primary root of maize inbred W64A elongates, basal and augmented K+(86Rb) uptake rates increase in regions increasingly distant from the apex and in regions at a fixed distance from the advancing apex. The pH-dependent process of augmentation requires aeration, begins without a lag period at pH 6, and is linear for 90 to 120 min. The augmentation potential of W64A(N) midzone root segments is minimal at 0.5 mM external K+ concentration and increases toward higher and lower external K+ concentrations. Augmentation is prevented at pH 4 in the Texas cytoplasmic male-sterile (T) version of inbred W64A but not in the male-fertile (N) version.Protein synthesis is required for development of K+(86Rb) uptake augmentation and probably also for maintenance of the augmented rate after development but apparently not for its expression. Inhibition of the maintenance of the augmented rate by low concentrations of chloramphenicol or cycloheximide does not prevent subsequent augmentation in their absence.Augmentation of amino acid uptake is not inhibited by 100 μg/ml chloramphenicol or 10 μg/ml cycloheximide, but augmentation of amino acid incorporation is inhibited by each. Augmentation of amino acid influx is sensitive to the toxin of Helminthosporium maydis, race T, in T roots but not in N roots, whereas augmentation of amino acid incorporation is only slightly more toxin-sensitive in T than in N root segments.
Physiological and ultrastructural changes occurring during germination of sclerotia of Sclerotium rolfsii
Authors: Chet I. , Timar D. , Henis Y.
Published: September 2008

Sclerotia of Sclerotium rolfsii germinated without the addition of an exogenous nutrient source. The germinating sclerotia excreted sugars and amino acids to the surrounding medium. Continuous washing of sclerotia prevented germination. In germinating sclerotia, the rate of uptake and incorporation into macromolecules of [3H]uridine and[3H]leucine was very low in the first 6 h but increased rapidly during the next 6 h. Electron microscopy of germinating sclerotial slices revealed that only the granulated medullar cells were involved in germ-tube formation. The germination tubes were very electron-dense and had a large number of mitochondria near their tips. The huge vesicles of the cortex cells appeared almost empty in the germinating sclerotium. It is suggested that these cells serve as an external nutrient reservoir for the germination tubes.
Uptake of magnesium by suspension cultures of plant cells (Ipomoea sp.)
Authors: Veliky I. A. , Rose D. , Zink M. W.
Published: September 2008

The magnesium level required to support full growth in batch suspension cultures of an Ipomoea sp. (Morning Glory) cell line in 2% sucrose media was less than 0.3 mM. The uptake of magnesium increased with increasing magnesium in the medium, and with increasing pH at constant magnesium level. In medium containing 1.0 mM (24 mg/ℓ) magnesium, a culture kept at pH 4.7 absorbed 6 mg of magnesium in 150 h; the corresponding figure for a culture kept at pH 6.9 was 19 mg.Much of the excess magnesium taken up by cells grown at the 1.0 mM magnesium level at various controlled pH levels could be extracted by grinding the cells in distilled water. The data suggest that under conditions of high magnesium supply and high pH these cells absorb large amounts (i.e. several milligrams per gram dry cells) of magnesium in excess of their requirement for growth.
Toxin produced by Phytophthora cryptogea active on excised tobacco leaves
Authors: Csinos Alex , Hendrix James W.
Published: September 2008

A sterilized aqueous extract of mycelium of Phytophthora cryptogea, grown on a defined medium, caused water-soaking of excised tobacco leaves within 12 h, laminar collapse within 20 h, and extensive dehydration within 48 h. This phenomenon was used as a bioassay to study the production and stability of the toxin. Many tobacco cultivars of diverse origin were all found to be susceptible, although degrees of susceptibility may exist. Bean, peas, pepper, tomato, and potato were not affected. Toxin was present in mycelium and culture filtrate throughout the growth cycle. The toxin was stable to autoclaving at acid pH but labile at alkaline pH. The activity of the toxin was augmented by dilution of mycelial extracts with 0.01 mol/kg NaH2PO4 rather than water. Treatment of leaves with light before or during incubation with the toxin reduced their susceptibility. Leaves collected for assay from the greenhouse in the afternoon were less sensitive to the toxin than those collected in the morning or at night. The toxin was equally active at incubation temperatures of 20 and 27 °C.
Isolation of protoplasts from unhardened and hardened tissues of winter rye and wheat
Authors: de la Roche A. Ian , Keller W. A. , Singh J. , Siminovitch D.
Published: September 2008

An enzymatic method is described for preparing stable protoplasts in high yield from non-hardened seedlings and hardened seedlings of winter wheat and rye capable in the hardened condition of tolerating −15 and −26 °C, respectively. The protoplasts were prepared from the epicotyl tissues which were found to be highly amenable to enzymic digestion. Metabolic competence and vitality of protoplasts were established by neutral red staining, cyclosis, regeneration of cell wall, and absence of alteration in lipid unsaturation.
An artefact in studies of the responses of respiration of bryophytes to desiccation
Authors: Gupta R. K.
Published: September 2008

The behaviour of respiration in response to desiccation treatments has been studied in the species Tortula ruralis (Hedw.) Gaertn., Mnium hornum (Hedw.), Dicranella palustris (Starke) Schp., Porella platyphylla (L.) Lindb., and Scapania undulata (L.) Dum. After 48 h of desiccation at 0 and 50% RH and rewetting for 32 h, the O2 uptake increased to about 6 times that of the control for Scapania, 2.5 times for Dicranella and about twice for Porella and Mnium: however, there was no significant increase for Tortula.Microscopic examination of the excess water collected from the shoots of Dicranella and Scapania 22 h after rewetting indicated the presence of a large number of microorganisms. Respiration experiments on the rewetting medium showed that the respiratory activity is due to microorganisms. The study shows that the stimulation of respiration because of microbial contamination could provide an indication of survival or injury in various bryophytes in response to desiccation stress. Respiration measurements however have serious limitations as indicators of cell viability in bryophytes.
A multivariate analysis of the niches of plant populations in raised bogs. I. Niche dimensions
Authors: Johnson E. A.
Published: September 2008

Principal component analysis is used as an empirical procedure for defining ecological niches in plant populations in raised bogs. The two niche dimensions identified within the raised bogs are related to mineral-ion concentration: (1) atmospheric input differences owing to proximity to the ocean and (2) mineral-soil groundwater influence. Both of these niche dimensions are related to the two important gradients in the surface water quality of the state of Maine. By comparing the principal component analysis study of the vegetation with the principal component analysis study of the physical environment (peat) using transformation analysis, their very similar but non-linear relationship is demonstrated.
A multivariate analysis of the niches of plant populations in raised bogs. II. Niche width and overlap
Authors: Johnson E. A.
Published: September 2008

The results of a principal components analysis are used to define the ecological niches of the plant populations in raised bogs. This paper examines the niche parameters of width and overlap. Dominance is positively related to niche width and inversely related to the number of species (richness). Richness is shown to be positively related to increased environmental complexity and predictability. Dominants appear to decrease in environments that are more complex and predictable because as a class these organisms are less opportunistic. Niche differentiation measured as overlap is greater in the richer, more environmentally complex and predictable parts of raised bogs.
Zoospore ultrastructure of Olpidium brassicae and Rhizophlyctis rosea
Authors: Barr D. J. S. , Hartmann V. E.
Published: September 2008

Zoospore cytology of two lettuce strains (from carrot and plantain) and a cabbage strain of Olpidium brassicae (Woronin) Dang, was compared with that of two isolates of Rhizophlyctis rosea (deBary & Woronin) Fischer. Olpidium brassicae zoospores contain four to six mitochondria grouped around the nucleus: microbodies are closely associated with the nucleus and mitochondria and casually associated with lipid bodies in the cytoplasm; ribosomes are scattered in the cytoplasm; a rhizoplast, 0.65 μm long, extends from kinetosome and non-functional centriole to an area near the nuclear membrane and consists of elongated, very fine fibrils crossed by electron-dense layers (striations) of varying thickness and density; the configuration of the layers of the rhizoplast in the lettuce strains differed from the cabbage strain. Rhizophlyctis rosea zoospores contain many (about 21) mitochondria grouped around the nucleus; elongated microbodies are conspicuous on the posterior and lateral sides of the nucleus and extend into the cytoplasm to lipid bodies; ribosomes are concentrated in an area around the nucleus and are partially enclosed by a net-like and folded arrangement of rough endoplasmic reticulum. Rhizoplasts of R. rosea consist of fine fibrils which extend from the kinetosome and non-functional centriole to the nucleus and are crossed by electron-dense layers; in one isolate the rhizoplast is 0.35 μm long and tapers to a point which is connected by fibrils to a flap of the nucleus in a posteriorly located nuclear pocket; in the other isolate it is 1.35 μm long, and expands into a cone-like segment which abuts onto the flattened, posterior face of the nucleus. The significance of the arrangement of organelles, and in particular the rhizoplast, in chytrid biosystematics is discussed.
Influence de la sécheresse sur la morphologie du système racinaire du Carex setifolia
Authors: Da S. , Hubac C. , Vartanian N.
Published: September 2008

Two kinds of roots, differing in width, can be grown from the regularly watered rhizome of Carex setifolia in strict cultural conditions. When plants are subjected to drought, which increases water deficit in the plants, root growth stops and the root tip necroses while lateral root initiation is stimulated. After watering again, growth of aerial parts is resumed, either from the oldest tiller after moderate desiccation, or from new tillers. The roots with the greatest diameter show an increase in thickness just behind the tip. The thickening lasts only 48 h after the beginning of watering, then roots grow normally again. Sometimes, several roots initiate from the thickened portion of the tuberized zone.An histological study of the normal roots and tuberized zones indicates that the difference occurs in the cortex. Whereas the cortex is lacunar in normal roots, it looks dense in tuberized parts of the roots and consists of radial rows of cells apparently generated from an extra-endodermic layer. This generative zone is normally present, though undeveloped and nonfunctional in normal roots of C. setifolia. Furthermore, a large amount of starch is found in the cortex of the thickened parts of the roots.
Shoots from Douglas-fir cultures
Authors: Winton Lawson L. , Verhagen Shirley A.
Published: September 2008

Whole Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seed embryos were placed on defined medium containing 0.05 or 0.1 mg/ℓ BAP (benzylaminopurine). One vigorous shoot usually grew from the tip of each swollen cotyledon on the 0.05 BAP medium, but small multiple shoots were produced on the 0.1 BAP medium. After transfer of embryos or excised cotyledons to medium without hormones, the vigorous shoots developed normally but the small multiple shoots did not. However, when cotyledons were grown on medium containing auxin and cytokinin, callus was produced that was isolated and subcultured monthly to fresh medium. Shoots were produced from subcultured cotyledon callus in 11 of 35 cultures, for a frequency of 31%. Two of 30–50 excised shoots rooted after treatment with 10 mg/ℓ IBA (indolebutyric acid). A few shoots were also produced from subcultured needle callus and from stem explant callus from young seedling material.
Perithecia and spore liberation of Claviceps purpurea: scanning electron microscopy
Authors: Colotelo Nicholas , Cook Wendy
Published: September 2008

Stromatal heads of Claviceps purpurea were examined with the scanning electron microscope. Perithecial walls are composed of flattened prismatic cells which serve as a common wall for the adjacent perithecia. Young perithecia contain asci enveloped in viscous material which is not evident in more mature perithecia or fixed preparations. Micrographs showing stages of ascus extrusion are presented. Ascospores are extruded and also ejected from perithecia.