bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrastructure of conidiogenesis in Drechslera sorokiniana
Authors: Cole Garry T.
Published: September 2008

An ultrastructural examination of conidiogenesis in Drechslera sorokiniana reveals that conidia develop enteroblastically through channels in the conidiogenous cell wall. These channels probably form by autolysis of the outer wall layers. The data support earlier concepts based on light-microscopic studies of conidium ontogeny in this and other developmentally related species of hyphomycetes. The surface morphology and relationship of wall layers of the conidium and conidiogenous cell at various stages of development are illustrated by scanning and transmission electron microscopy, respectively. This information is summarized in a diagrammatic interpretation of conidiogenesis. Cytodifferentiation during conidium formation and conidiogenous cell proliferation is also examined. A possible association between organelle migration in developing conidiogenous cells and fascicles of microfibrils, proposed in an earlier paper, is discussed. A suggestive explanation is presented for the accumulation of microbodies in conidium initials and apices of proliferating conidiogenous cells. Layers of endoplasmic reticulum which are terminally hypertrophied and juxtaposed to the plasma membrane of developing conidiogenous cells are also noted.
Pseudorobillarda Nag Raj et al., a later homonym of Pseudorobillarda Morelet
Authors: Raj T. R. Nag , Morgan-Jones G. , Kendrick Bryce
Published: September 2008

Pseudorobillarda Nag Raj, Morgan-Jones, and Kendrick is a later homonym of Pseudorobillarda Morelet, typified by P. phragmitis (Cunnell) Morelet. The status of P. bambusae Nag Raj, Morgan-Jones, and Kendrick; P. indica Nag Raj, Morgan-Jones, and Kendrick; P. agrostidis (Sprague) Nag Raj, Morgan-Jones, and Kendrick; and P. muhlenbergiae (Sprague) Morelet, is indicated.
Continuous automatic measurement of rhythms in fungal respiration using a gas chromatograph
Authors: Smith Roger S.
Published: September 2008

The long-term measurement of aerobic fungal respiration, both on an agar medium and on wood blocks, was possible using a gas-chromatographic technique for the detection of the carbon dioxide. This method was fully automated to analyze gas samples sequentially from eight or more growth chambers, after variable but determined time periods. It provided a precise quantitative measure of the respired carbon dioxide, presented both in the form of punched computer tape and normal printed teleprinter output. This apparatus worked continuously for several years without serious breakdown.The fungi Lentinus lepideus, Lenzites trabea, Poria monticola, and several strains of Coniophora puteana all showed a rhythm in their respiration which was not controlled by temperature or light. The magnitude and frequency of the rhythmical peaks in carbon dioxide production varied between fungi and, although there was considerable variation between different isolates of the same species, the separation of these species of fungi based on their different patterns of respiration was possible.
Does the resting potential of Chara braunii have an electrogenic component?
Authors: Pickard William F.
Published: September 2008

The vacuolar resting potential and the membrane resistivity of Chara braunii are studied (i) as a function of ionic composition of the bathing medium, (ii) in the presence of the metabolic inhibitors cyanide and salicylhydroxamic acid, and (iii) as a function of temperature. Substitution of acetate for chloride produces a marked hyperpolarization, sulfate for chloride a small hyperpolarization, sodium for potassium a marked hyperpolarization, and rubidium for potassium a small hyperpolarization; the membrane resistivity showed no readily discernible pattern of variation with these substitutions. The metabolic inhibitors produced a linear decline of resting potential accompanied by a several-fold increase of membrane resistivity. Cooling to levels near 0 °C produced a several-fold increase in resistivity but not necessarily a depolarization. Suitable heating at or above 40 °C could produce a linear depolarization and a several-fold increase in resistivity. The data are interpreted in terms of a depolarizing electrogenic cation-chloride influx pump, a hyperpolarizing hydrogen-ion efflux pump, and a membrane resistivity linked to the hydrogen ion pump.
Seasonal fluctuation in respiration of aging xylem in relation to heartwood formation in Pinus radiata
Authors: Shain Louis , Mackay J. F. Graham
Published: September 2008

Respiratory activity in xylem tissues of Pinus radiata was monitored during the growing and dormant seasons by manometry as well as by histochemical localization of malic and glucose-6-phosphate dehydrogenases and by quantitative estimation of malic dehydrogenase. During the dormant season, respiration and activity of malic dehydrogenase were significantly greater (1% probability level) in the transition zone separating sapwood from heartwood than in middle and inner sapwood. These results were supported by enzyme histochemistry, which indicated a substantial increase in activity of glucose-6-phosphate dehydrogenase in the transition zone, particularly during the dormant season. It is suggested that heartwood formation occurs mainly during this time.
The algal microflora of a string mire in relation to the chemical composition of water
Authors: Flensburg T. , Sparling J. H.
Published: September 2008

Twenty-one samples were examined for algal species diversity. Samples contained between one and 35 species with a mean of 10.6 species per sample. The greatest diversity of species occurred in samples collected from large flarks or bog lakes. Hummock communities, especially those with abundant Sphagnum rubellum contained fewest algae. All samples showed a predominance of Desmidiales.General ionic levels in the string mire were low; however, species of the genera Euastrum, Micrasterias, and Staurastrum occurred frequently in the sites richer in nutrients. More species were found in wetter than in drier sites.The presence of species characteristic of more base-rich conditions may be related to the rate of water flow through the mire.
Effect of changes in carbohydrate concentration on the rate of net photosynthesis in mature leaves of Abies balsamea
Authors: Little C. H. A. , Loach K.
Published: September 2008

The hypothesis that photosynthate accumulation within a leaf inhibits the ongoing rate of photosynthesis was investigated in 6-year-old balsam fir trees. Rates of net photosynthesis and transpiration, and concentrations of starch, total sugar, chlorophyll, and water were measured in 1-year-old or fully expanded, current needles, and leaf resistances to carbon dioxide transfer were calculated. The several-fold rise and fall in the content of carbohydrate (mostly starch) that occurs naturally in 1-year-old needles before and after budbreak was correlated positively rather than negatively with the photosynthetic rate. Shading during the normal period of starch accumulation decreased the concentrations of both starch and total sugar, but did not increase photosynthesis. Continuous cooling of the base of a branch to 2 °C to inhibit translocation of photosynthate did not affect the photosynthetic rate during a 2-week period, nor did it cause carbohydrate accumulation, as measured at the end of the experiment. Removing a ring of bark from a branch base resulted in a large increase in the foliar concentration of starch (but not total sugar) and a small decrease in photosynthesis. However, the concomitant decrease in moisture content, not the accumulation of starch, was more probably the cause of the reduced photosynthesis. We conclude that the rate of photosynthesis in fir needles, at least under normal growing conditions, is not influenced by photosynthate accumulation.
An important new diploid Avena species discovered on the Canary Islands
Authors: Baum B. R. , Rajhathy T. , Sampson D. R.
Published: September 2008

Avena canariensis sp. nov., 2n = 14, is described from the Canary Islands. Its spikelets have non-disarticulating upper florets and bidentate lemmas, suggesting the evolutionary sequence: A, canariensis (2x) → A. magna (4x) → A. sterilis (6x). Hence it is a putative ancestor of the 6x cultivated oats. The karyotype consists of two pairs of satellited chromosomes, four pairs with median and one pair with submedian centromeres, suggesting affinity with the A genome diploid avenas. It was found on a diversity of natural and disturbed sites in the uplands of Fuerteventura, but not as a weed of field crops.
Plant adjustment to osmotic stress in balanced mineral-nutrient media
Authors: Cooper A. W. , Dumbroff E. B.
Published: September 2008

Studies of salt tolerance of plants grown in balanced nutrient solutions revealed that growth rate was more a function of the duration of the applied stress than the rapidity with which a particular osmotic concentration was reached in the root medium.The low osmotic potentials initially attained by plants subjected to osmotic stress resulted from both a decrease in water content and an increase in ion concentration in the plant tissues. However, the importance of dehydration in the adjustment process decreased within a relatively short time, and ion uptake was noted to be the predominant factor in the adjustment of the plant sap throughout the vegetative period. With the exception of restrictions on growth, symptoms of ion toxicity were not observed with these balanced solutions, although exposure to stress in one of the treatment series lasted for 84 days.Substantial increases in osmotic potential on the removal of stress were apparently the result of passive diffusion of ions back to the substrate, rather than an increase in the water content of the tissues as previously reported. The cations K+ and Ca2+ provided the major contribution to changes in the osmotic potential of the foliar sap, but significant changes were noted in all of the ions measured.
Studies in the Alismataceae. II. Inflorescences of Alismataceae
Authors: Charlton W. A.
Published: September 2008

Aspects of morphology and development of alismataceous inflorescences have been studied. The inflorescences are always terminal, and transition of the vegetative meristem to the reproductive state is accompanied by the formation of a large vegetative bud in the axil of the last foliage leaf formed before transition. The inflorescences of the family are almost all built on a common plan with bracts in false whorls of 3 on the main axis (and branches when present). The basic structure subtended by the bracts is a bostrycoid complex of flowers (or branches and flowers in the lower parts of some large inflorescences). Modifications of various kinds occur in different cases: the bostryx may be reduced to a single flower; vegetative buds may occur in flower positions in bostryces; a single vegetative bud may replace a whole bostryx in inflorescences much modified in relation to vegetative reproduction. Development of bostrycoid complexes is dependent on formation of buds in prophyll axils and does not occur where prophylls cannot be detected. Some species have inflorescences in which a diversity of lateral structures is associated with each pseudowhorl of bracts and these are termed heterogeneous inflorescences, in contradistinction to homogeneous inflorescences, in which all the lateral structures in a pseudowhorl are of the same kind. Main and branch axes of an inflorescence normally terminate in a flower. Exceptions occur in some (possibly advanced) types in which inflorescence growth is terminated by abortion, and in specialized inflorescences modified in relation to vegetative reproduction which have unlimited growth. The data presented are discussed from systematic, evolutionary, and morphogenetic points of view.
Cytology of Podosordaria leporina
Authors: Rogers Jack D.
Published: September 2008

The haploid chromosome number of Podosordaria leporina is 7. Ascospores are uninucleate when formed, becoming binucleate via a mitosis. Maturing ascospores usually are uninucleate owing to loss of a nucleus. Possible taxonomic significance of these cytological characteristics is discussed.
Environmental factors influencing basidiospore discharge in Polyporus tomentosus
Authors: Bohaychuk W. P. , Whitney R. D.
Published: September 2008

Basidiospore discharge rates by sporophores of Polyporus tomentosus were highest at moderate temperatures (16–22 °C) and high relative humidity (85–100%), with either low light intensity or darkness. Discharge rates decreased abruptly when relative humidity was lowered to about 70% in continuous darkness and at constant temperature. Above 85%, fluctuations in relative humidity had little effect on spore discharge rates. In darkness and high relative humidity, discharge rates were positively correlated with temperatures between 5 and 23 °C. Illumination disrupted both these relationships. Under natural conditions, the periodicity of discharge rates was not correlated with the periodicities of light, relative humidity, or temperature, but appeared to be governed by the interaction of these three factors. Polyporus tomentosus discharged spores at a high rate on cloudy days when temperatures were moderate. Highest rates of discharge occurred in the evening and lowest rates occurred in the early morning.Basidiospore discharge rates did not appear to be related to other factors studied, for example, sporophore size, growth rate, and moisture content, or soil moisture and nutrient content. Sporophores required at least 180% moisture content to discharge spores at high rates.
The eyespot of Chlamydomonas eugametos: a freeze-etch study
Authors: Nakamura Kazuo , Bray D. F. , Costerton J. W. , Wagenaar E. B.
Published: September 2008

The ultrastructure of the eyespot region of Chlamydomonas eugametos was studied with the freeze-etch technique. In the region of the eyespot the outer chloroplast membrane, when fractured medially, showed the presence of bulgings which appeared as either depressions or bumps depending on the cleavage plane. These deformations of the outer chloroplast membrane produced by the granules of the eyespot are about 80 mμ in diameter and form ordered arrays of 800 or more particles.
Biochemical differentiation in flax tissue culture. Phenolic compounds
Authors: Liau Sally , Ibrahim R. K.
Published: September 2008

Flax cotyledonary tissue loses its biosynthetic potential for flavonoid and sinapoyl compounds when grown on agar medium containing sucrose, NAA, kinetin, and coconut water. The pattern of phenolic compounds of the callus tissue, however, exhibits a marked differentiation which is related to the levels of growth substances or phenolic precursors added to the culture medium. The induced formation of a C-glycoflavone (iso-orientin) and an anthocyanin (cyanidin-3,5-diglucoside) under high levels of kinetin and white light was demonstrated.
Is cinnamic acid 4-hydroxylase of potato a light-induced enzyme?
Authors: Camm E. L. , Towers G. H. N.
Published: September 2008

Cinnamic acid 4-hydroxylase from potato tuber tissue does not appear to be stimulated by light, but only by the wounding of the tissue. This behavior is in contrast to that observed in other tissues.
Local lesion formation by ultraviolet irradiation on leaves systemically infected with TMV
Authors: Takagi Yasushi , Sugimura Yukio
Published: September 2008

When the leaves of Xanthi tobacco systemically infected with tobacco mosaic virus were irradiated with ultraviolet light, local lesions were induced on the treated leaves.
Environmental regulation of the oxygen effect on apparent photosynthesis in wheat
Authors: Jolliffe P. A. , Tregunna E. B.
Published: September 2008

A closed gas exchange system was used to survey the apparent rates of photosynthesis by young wheat shoots in a wide range of O2 concentrations (O2), CO2 concentrations (CO2), temperatures (T), and radiant flux densities. The results are expressed graphically and by equations. The carbon dioxide compensation point (ΓH) conformed to the equation ΓH = O2e(0.0428T − 12.1). The relationship between the apparent rates of photosynthesis in the presence (PH) and absence (PL) of inhibitory concentrations of oxygen was described by the equation PH = PLk loge(CO2/ΓH) where k was independent of the prevailing environmental conditions and [Formula: see text].
Cytoplasmic and nuclear inclusions in leaf cells infected with Datura shoestring virus (DSV)
Authors: Weintraub M. , Agrawal H. O. , Ragetli H. W. J.
Published: September 2008

Exudates and purified preparations of leaves infected with Datura shoestring virus (DSV) contained particles 720–750 × 16 nm. Light microscopy of DSV-infected Datura metel leaves showed that the shoestring portions consisted mainly of midrib, with the tissues arranged as in healthy leaves, but without a lamina. Ultrathin sections of shoestring portions of D. metel leaves, and of laminae from infected leaves of D. metel, Nicotiana glutinosa, and N. debneyl, contained cytoplasmic lamellar inclusions as dense bands and pinwheels, in all parenchymatous tissues, and often in X-bodies. Long, rod-shaped particles were frequently arranged in regular array along the arms of the lamellar inclusions. Structures composed of ribosome-like particles were often found arranged regularly in an alternating double row in the cytoplasm. Nuclei contained tubular inclusions with an outside diameter of 35–40 nm. The classification of DSV, which is not serologically related to potato virus Y, is discussed, and it is suggested that the present practice of classifying any virus that induces formation of lamellar inclusions, regardless of size or serological relationships, in the PVY group is misleading. A proposed alternative to this practice, with a purely descriptive basis, is that all such viruses be called lamellar inclusion forming (LIF) viruses.
The development of the embryo sac of sunflower Helianthus annuus before fertilization
Authors: Newcomb William
Published: September 2008

The megaspore mother cell of sunflower Helianthus annuus L. undergoes two meiotic divisions to form a linear tetrad of haploid megaspores. The chalazal megaspore increases in size while the other megaspores and the nucellus degenerate such that the integumentary tapetum is adjacent to the embryo sac. Mitotic divisions occur forming the coenocytic two- and four-nucleate embryo sacs and the seven- or eight-nucleate six-celled embryo sac. Electron-microscopic observations suggest that the antipodals are very active synthetically but start degenerating before fertilization. Similarly the synergids are also apparently very active synthetically before fertilization as judged by the presence of extensive regions of dilated rough endoplasmic reticulum and many Golgi bodies and associated vesicles. The egg cell is characterized by the presence of many free ribosomes and small undifferentiated plastids. The central cell contains many circular strands of rough endoplasmic reticulum, lipid droplets, and large clusters of apparently active Golgi; it is a transfer cell resulting from the presence of embryo sac wall ingrowths. The development and the possible nutritional interrelationships of the megagametophyte and surrounding tissues are discussed.
Studies in the Alismataceae. III. Floral anatomy of Ranalisma humile
Authors: Charlton W. A. , Ahmed A.
Published: September 2008

The flower of Ranalisma humile is comparable in morphology to those of other alismads. The vascular anatomy is noteworthy. Flowers of R. humile are provided with a major (central) vascular system supplying androecial and gynoecial vasculature and a variable amount of the sepal and petal vasculature, and a minor (peripheral) system which supplies the rest of the perianth vasculature. There is very little anastomosis between the two systems. It is suggested that the variability of perianth vascular supply reflects variability in timing of differentiation events. The occurrence of an almost independent peripheral vascular system is probably of significance in a consideration of the relationship of Ranalisma humile to other alismads.
A survey of anthocyanin pigments in seedling legumes
Authors: Nozzolillo Constance
Published: September 2008

Light-grown seedlings of 88 species of legumes were examined for anthocyanins. No red pigmentation developed in 22 species. In nearly all the 66 pigmented species, the red color was subepidermally located. Pigment determination of 40 species showed cyanidin glycosides to be the most common. In five of seven species of Phaseolus and the closely related Glycine max, however, malvidin glucoside was predominant. In four of five species of Vicia as well as in two species of Phaseolus, delphinidin glycosides were the major pigments.
Studies on the haustorium of Castilleja (Scrophulariaceae). I. The upper haustorium
Authors: Dobbins David R. , Kuijt Job
Published: September 2008

The portion of the Castilleja secondary haustorium external to host tissues was investigated at the light- and electron-microscopic levels. One or more haustoria may be present along a single lateral root; however, primary roots of Castilleja may also have haustoria. A localized development of root hairs usually precedes haustorial formation. The first sign of haustorial formation is the swelling of root cortical cells which gives rise to a nearly spherical structure. Eventually, the haustorial epidermis is obliterated at the contact surface between parasite and host. The upper haustorium has a complex internal structure consisting of several distinct cell zones. The pericycle gives rise to a parenchymatous zone of cells adjacent to the plate xylem. Later, collenchyma differentiates in the center or core of the haustorium and is surrounded by a cortical zone of parenchyma cells. This is the first report of collenchyma tissue in a haustorium of any parasite. Thus, a mature Castilleja haustorium consists of a plate xylem zone, an adjacent parenchymatous zone, a centrally located collenchyma zone, and a peripheral cortical zone. The endophyte is initiated from hypodermal parenchymatous cells located between the collenchyma core and the haustorial surface. Lipid is abundant in the young endophyte and paramural bodies are common in many cells. Strands of vessel members differentiate at random and are sheathed by thin-walled densely cytoplasmic cells. Vessel members occur within the collenchyma zone as well, and frequently contain starch and other coarsely granular materials. No phloem was found in the upper haustorium of Castilleja. The upper haustorium of Castilleja and of other members of the Scrophulariaceae are compared.
Inhibition by cytochalasin B of sucrose transport in isolated phloem strands of Heracleum
Authors: Thompson R. G. , Thompson A. D.
Published: September 2008

Cytochalasin B was found to inhibit the translocation of 14C-sucrose applied to isolated phloem strands of Heracleum. This supports the theory that microfilaments are involved in translocation since this drug is known to inhibit microfilament action in other organisms.
Secretion of acid polysaccharides by the brown alga Pilayella littoralis
Authors: Leppard Gary G.
Published: September 2008

The vegetative cell of Pilayella littoralis has been chosen as an advantageous experimental system for the study of acid polysaccharide secretion. Alginic acid is shown to be quantitatively important by extract analysis. Cytochemistry reveals its localization in the cell wall and cytoplasmic structures referred to here as TBO particles (unpigmented particles, seen by the optical microscope, which take up vitally the basic dye toluidine blue O). Radioautographic and radioisotopic extract analyses suggest that alginic acid is polymerized in the cytoplasm by TBO particles. From there it is transported, probably by streaming of the same particles, to the cell surface, where it is extruded into the cell wall.
Developmental morphology and taxonomy of the genus Arbuscula Batista and Peres
Authors: Subramanian C. V. , Vittal B. P. R.
Published: September 2008

Observations on the developmental morphology of Arbuscula eugeniae Batista and Peres (the type species of the genus) are given. The fungus produces largely pseudoparenchymatous bulbils generated by and surrounding a core of hyphae whose continued extension and activity result in the successive acropetal production of columnar branching chains of bulbils. The genus Arbuscula is therefore classified in the Mycelia Sterilia.
Pathological anatomy of conifer needle necrosis
Authors: Stewart Dennis , Treshow Michael , Harner Frances M.
Published: September 2008

The pathological anatomy of pine needle necrosis caused by major environmental stresses was investigated to determine if histological responses could provide a diagnostic tool. All stresses studied caused a general hypertrophy of the epithelial tissue of the resin canals, occluding these ducts. Granulation of transfusion and mesophyll parenchyma cells was also a general response to stress. Hypertrophy of the phloem cells and transfusion parenchyma was caused by almost all stresses in some instances but was most consistent for necrosis caused by natural senescence, drought, or fluoride. Collapse of the mesophyll cells best characterized necrosis caused by ozone, sulfur dioxide, salt, or boron toxicity. The greatest value of microscopic examination of the tissues adjacent to the necrotic areas was found to lie in the elimination of certain pathogens, narrowing the possible causal agents. Histological examination could ascertain when certain air pollutants were not responsible for a particular injury; for instance, the absence of mesophyll collapse can definitely eliminate sulfur dioxide as a cause of necrosis. Conversely, though, presence of mesophyll cell collapse, because of its ubiquitous nature, could not establish etiology.
Geotropic response patterns of the Avena coleoptile. II. Induction at low temperature
Authors: Pickard Barbara Gillespie
Published: September 2008

The gravity reception system of the coleoptile of Avena sativa L., cv. Victory, deteriorates progressively and rapidly at 2 °C. In contrast, at 2 °C there is no progressive diminution of the ability of the geotropically induced coleoptile, when returned from 2 °C to 25 °C, to carry out the secondary processes leading to curvature.For the Avena coleoptile, it is impossible to isolate primary reactions by means of low temperature as has been reported successful for the Helianthus hypocotyl; induction and curving proceed concurrently at 2 °C.
Distribution of 14C-labeled metabolites in mycorrhizal and nonmycorrhizal lodgepole pine seedlings
Authors: Ahrens J. R. , Reid C. P. P.
Published: September 2008

Four days after 14CO2 assimilation, the distribution of 14C-labeled metabolites in mycorrhizal and nonmycorrhizal pine seedlings was investigated by use of autoradiography, thin-layer chromatography, and liquid scintillation techniques. Mycorrhizal formation was accomplished by growing the lodgepole pine (Pinus contorta Dougl.) seedlings in axenic culture with the fungal symbionts Thelephora terrestris (Ehrh.) Fr., Cenococcum graniforme (Sow.) Ferd. and Winge, and Rhizopogon vinicolor A. H. Smith.Although no significant differences between ectomycorrhizal and uninfected pines were found in the distribution of 14C-labeled metabolites after seedling harvest, important trends were noted in both seedling types with respect to the 14C distribution. Total radioactivity within both mycorrhizal and nonmycorrhizal seedlings was highly correlated with shoot dry weight. Most activity was present in ethanol-soluble fractions. The percentage of activity in ethanol-soluble fractions was greater in roots than shoots. Sugars formed the greatest percentage of the labeled, ethanol-soluble fractions, with sucrose the most common. The roots of all plants analyzed had higher percentages of sucrose and lower percentages of hexoses than did the shoots. Of the hexoses, glucose was more prominent in the shoots and fructose more prominent in the roots of both types of seedlings. Greater quantities of 14C-labeled organic acids and amino acids were found in the shoots than in roots. Both mycorrhizal and nonmycorrhizal plants had similar mean 14C activities in root exudate fractions collected in distilled water. This activity was not correlated with root dry weight or 14C activity within the plant.There was no evidence to support the hypothesis that mycorrhizal development promotes increased translocation of assimilates to the roots or results in increased soluble carbohydrate levels.
Developmental changes in radish caused by brief end-of-day exposures to far-red radiation
Authors: Proctor J. T. A.
Published: September 2008

Five-minute exposure of radish plants to far-red radiation at the end of each day after the development of the first two leaves significantly increased plant height, leaf length and width, root length, fresh weight of leaves, and reduced the chlorophyll content of leaves.
Representation of leaf orientation data by equal-area projection techniques
Authors: Douglas George W. , Ramsden John
Published: September 2008

Two equal-area projection techniques (point diagrams and contoured density diagrams) are presented for use in analyzing three-dimensional leaf orientation data. The diagrams display both azimuths and inclinations simultaneously, and allow a rapid visual evaluation of the data. Leaf orientation measurements from three specimens of Nerium oleander are used to illustrate the techniques.In addition, the point diagram permits the grouping of data from a particular canopy layer into regions, simultaneously considering both azimuths and inclinations as well as leaf area. The contoured density diagram allows these regions to be selected on the basis of the actual distribution of leaf area.
Nonspiral androecium and gynoecium of Sagittaria latifolia
Authors: Singh V. , Sattler R.
Published: September 2008

Developmental studies do not confirm the general opinion that the androecium or the gynoecium is spiral in Sagittaria latifolia. After the inception of three sepal primordia, three bulges (petal–stamen primordia) are formed on radii alternating with the sepal primordia. On each petal–stamen primordium a petal is initiated and subsequently a pair of stamens in the male floral bud and staminodia in the female floral bud. Next, two antesepalous primordia are formed between the first paired primordia. Further stamens (or staminodia and carpels in the female floral bud) are formed centripetally, more or less alternating with the previous ones at subsequently higher levels.
The uptake of alanine-14C by soybean root cells grown in sterile suspension culture
Authors: King J. , Oleniuk F. H.
Published: September 2008

A method has been adapted to follow quantitatively the uptake of L-alanine-14C, and presumably other 14C-labeled compounds, into soybean (Glycine max. cv. Mandarin) root cells growing in sterile suspension culture. Details are given of the growth and assay requirements needed to yield reproducible data.When alanine-14C uptake is followed into cells grown in the presence of nitrogen until immediately before assaying, a double reciprocal plot of velocity against alanine concentration yields a straight line which passes through zero, indicating that increasing substrate concentration will not saturate this uptake system. When cells are starved of nitrogen for 12 h before they are assayed, uptake rates increase by more than 100 times and a substrate-saturable uptake system can be detected. A Km value of 2.55 × 10−6 M was calculated. This saturable system is also strongly and rapidly affected by the respiratory inhibitors 2,4-dinitrophenol (DNP) and sodium azide.
Three new Hyphomycetes from litter
Authors: Subramanian C. V. , Vittal B. P. R.
Published: September 2008

Three hyphomycetes collected on litter in India are described: Kramasamuha sibika gen. et sp. nov., Sympodiella laxa sp. nov., and Zanclospora indica sp. nov.
Compositional studies on the cell walls of the synnema and vegetative hyphae of Ceratocystis ulmi
Authors: Harris James L. , Taber Willard A.
Published: September 2008

The composition of the cell walls of synnemal and vegetative hyphae of Ceratocystis ulmi was studied by fractionation and assay of released compounds. Residues after enzymatic hydrolyses were examined by electron microscopy. The synnemal wall was found to have 67% carbohydrate, 4.52% amino sugar, 5.02% protein, 1.6% lipid, and 0.59% ash, which accounted for 78.7% of the cell wall. The vegetative hyphal wall contained 56% carbohydrate, 3.44% amino sugar, 7.92% protein, 4.5% lipid, and 1.45% ash, which totaled 73.3% of the wall weight. Sugars identified were D-glucose, D-mannose, D-galactose, and L-rhamnose. Enzymatic hydrolysis of both wall types by cellulase and laminaranase indicated the presence of beta-1,3 and beta-1,4 linkages of glucose polymers. N-acetylglucosamine was liberated by chitinase. Most of the 16 amino acids detected in each wall type were at least twice as abundant in vegetative hyphal walls as in synnemal hyphal walls. Cellulase and laminaranase treatment of cell walls revealed a fibrillar structure. Chitinase-treated walls did not appear as fibrous, suggesting that the fibrous structure may be mostly chitinous. Synnemal cell walls are covered by electron-dense granules which may correspond to the pigment in the synnemal hyphae.
Production, storage, and use of photosynthate during shoot elongation in balsam fir (Abies balsamea)
Authors: Loach K. , Little C. H. A.
Published: September 2008

Rates of net photosynthesis and dark respiration of 1-year-old and currently developing foliage were measured in the uppermost (i.e. 1-year-old) whorl of branches of 6-year-old balsam fir trees (Abies balsamea (L.) Mill.) during the period of extension growth of the current shoot. The rates were integrated to estimate net dry matter production by the two ages of foliage, and compared with dry matter requirements for growth of the new shoot (estimated from a regression equation of length over dry weight), and with cambial growth in the 1-year-old shoot (estimated from periodic harvests). The surplus of production over use in these two sinks was stored temporarily in the 1-year-old foliage or exported from the branch, the latter predominating. Two periods in which a large proportion of the photosynthetic production was exported (corresponding roughly to the months of May and July) were separated by a period when export was relatively low. At this intermediate time, current photosynthetic production was minimal and local growth demands were at their highest. Photosynthates stored in the 1-year-old foliage before budbreak supplemented current photosynthesis and permitted export to continue, except for a few days at the end of June. The contribution from stores in the old foliage, however, never exceeded one-third of current photosynthetic production. When extension growth terminated, a second transient storage peak occurred in the 1-year-old foliage for about 2 weeks. These observations explain the commonly observed reduction in root growth during current shoot extension, and corroborate results from studies made by other investigators using radioactive tracers.
Rapid release of peroxidase by peanut cells in suspension culture
Authors: Huystee R. B. van , Turcon G.
Published: September 2008

Peanut cells in a suspension culture were studied with regard to the process of peroxidase release and some ultrastructural features that appeared to relate to this process. By means of gel filtration on Sephadex G-200 it was established that protein released into the medium had the same molecular weight as the peroxidase found in this medium. From information gained through the electron-microscopic studies and from incorporation of labeled leucine, it may be deduced that the metabolic rate of these cells is very high. Within 2 h after incubation with radioactive leucine it was noted that newly synthesized protein was released by the cells into the medium. This protein had also the same characteristics of peroxidase and its synthesis and subsequent appearance in the medium could be reduced by incubation in the presence of cycloheximide. A possible explanation for the presence of these large quantities of peroxidase is discussed.
The effect of ozone on leaf cell membranes
Authors: Swanson Elizabeth S. , Thomson William W. , Mudd J. Brian
Published: September 2008

The objective of this study was to determine the effects of ozone on membrane lipids and on the electron-density patterns of cell membranes in electron micrographs. Analysis of fatty acids from tobacco leaves fumigated with ozone indicated that there was no significant difference between the ozone-treated and the control plants in the relative amounts of the fatty acids. This suggests that if the primary site of ozone action is unsaturated lipids in membranes then the amounts of affected unsaturated fatty acids are too small to be detected by gas chromatography. In support of this, characteristic electron-microscopic images of membranes are observed in cells of fumigated leaves. However, measurements of the length and width of the chloroplasts and the determination of axial ratios indicated that the ozone treatment resulted in a shrinkage of the chloroplasts. In contrast, mitochondrial changes are apparently explained in terms of ozone-induced swelling.
The effect of lipid extraction on electron-microscopic images of plant membranes
Authors: Swanson Elizabeth S. , Thomson William W. , Mudd J. Brian
Published: September 2008

An evaluation was made of the role of lipids in electron-microscopic membrane images of plant cells by comparing extracted lipids with changes in the ultrastructural membrane images. Lipids were extracted from tobacco leaves with a series of acetone concentrations. In a parallel series, glutaraldehyde fixation preceded lipid extraction. Thin-layer chromatography of the acetone extracts showed no major difference in the lipids extracted with and without glutaraldehyde fixation, but different concentrations of acetone removed specific lipids. Electron micrographs of tissues not previously fixed with glutaraldehyde showed a disruption of all membrane images at acetone concentrations greater than 30%. From these studies it appears that lipids are involved in the formation of electron-microscopic membrane images, but to a different degree in the various membranes. The general form of mitochondria and chloroplast grana was not dependent upon lipid, though lipid was required for the typical density pattern of the granal partitions. The bounding membranes of the mitochondria and chloroplasts were lost with extraction of galactolipids, sulfolipids, and phospholipids. The plasmalemma, tonoplast, and microbody membranes lost their typical density pattern and their structural integrity with the extraction of phospholipids.
Plant composition and species relations on the Huntingdon Marsh, Quebec
Authors: Auclair Allan N. , Bouchard André , Pajaczkowski Josephine
Published: September 2008

The purpose of this study was to identify significant species relationships and underlying ecological gradients characteristic of the Huntingdon Marsh, Quebec. In 1970, one hundred and seven 1-m2 samples of plant biomass were obtained from the marsh in conjunction with environmental measurements. These data were later analyzed using principal-components analysis.The marsh complex divided unambiguously into emergent aquatic and sedge meadow communities on the basis of distinct environmental and compositional differences. Equisetum fluviatile, Scirpus fluviatilis, Eleocharis palustris, and Scirpus validus were major species in the emergent aquatic community. Respectively, these species dominated 29, 25, 16, and 14% of 51 quadrats on a dry weight basis. Water depth accounted for almost one-third of the species variation in this community. Interaction between submerged and floating forms and competitive exclusion between dominant species explained much of the remaining species variance.On a dry weight basis, Carex aquatilis, C. lacustris, Calamagrostis canadensis, and Typha angustifolia dominated 36, 16, 16, and 11% of the 56 quadrats on the sedge meadow. As a group, Carex spp. dominated 63% of the quadrats. Disturbance related to chance perturbations, water depth, and the incidence of fire accounted for much of the variation in this community.The organization of emergent and sedge meadow communities was discussed in relation to continuum and community concepts with particular reference to relative changes in discontinuity of species relationships across the environmental gradient.
Microlychnus gen. nov., a lichenized hyphomycete from western conifers
Authors: Funk A.
Published: September 2008

Microlychnus epicorticis gen. et sp. nov. is a lichenized hyphomycete found on the bark of three species of conifers growing in the coastal rain forest of British Columbia and Alaska. It is characterized by a synnematous fruiting structure bearing minute phialides which produce filiform conidia; its associated alga was not identified.
The genus Crepidotus in Hawaii
Authors: Ueki Robert , Smith Clifford W.
Published: September 2008

Ten species of the genus Crepidotus are described from Hawaii. They are Crepidotus alabamensis, C. amygdalosporus, C. appalachianensis, C. applanatus var. globigera, C. avellaneus, C. citrinus, C. mollis, C. nephrodes, and C. rhizomorphus. One new species, C. bakerae, is proposed. Keys and distinctive characters of each species are provided. It is suggested that most of the species came from the North American continent.
Growth kinetics of Marquis wheat. V. Morphogenic dependence
Authors: Macdowall F. D. H.
Published: September 2008

The rate coefficients of the exponential period of growth of the vegetative organs of Marquis wheat were changed and made biphasic by the morphogenesis of the stem apex from the vegetative to the flowering state. The rate coefficient of stem elongation was lower in the initial or vegetative phase than later, and it was initially insensitive to temperature up to 20 °C but temperature sensitive in the final or flowering phase from 10 °C to 30 °C. In contrast the growth coefficients of plant, shoots, and roots computed from measurements of dry weight were higher in the first phase than in the second phase and increased with temperature to a maximum at 20 °C in both phases. The differences were attributed to the less autotrophic nature and initially more limited growth of the stem. The raised stem-growth coefficient in the flowering phase was compensated by slowed growth of its shoot. Tillers grew most rapidly, successive tillers more so, and accounted for the previously observed dominant growth of "stems" as stems plus leaf sheaths. The change of slope within the exponential plots was not noticed in previous work at 25 °C and it portends higher maximal coefficients for vegetative (initial phase) plant growth than those previously estimated from the entire exponential period. However, under optimal conditions the growth coefficient of the whole plant seems to be internally limited to about half that of one or another organ.
Studies on lichen-dominated systems. V. A primary survey of a raised-beach system in northwestern Ontario
Authors: Kershaw K. A. , Rouse W. R.
Published: September 2008

A series of raised-beach systems in northwestern Ontario were examined using principal-component analysis and a number of broad plant associations were delimited. A definite trend exists from the younger raised beaches adjacent to the coastline, to the older ridges examined some 8 km inland. This trend has been characterized by the major species involved and by the plant associations relating to specific ridge groups. The paper also lays the foundation for a series of detailed studies which are currently in progress.
Scanning electron microscopy of sporangia of Coelomomyces
Authors: Bland C. E. , Couch J. N.
Published: September 2008

The scanning electron microscope is used in an examination of the sporangia of 18 described and 3 undescribed species of Coelomomyces. As a possible aid to taxonomy, those species considered in this study are grouped into eight morphologically recognizable groups. The complementary use of light microscopy and scanning electron microscopy in studies of this type is emphasized.
Ethylene production in xylem of Pinus radiata in relation to heartwood formation
Authors: Shain Louis , Hillis W. E.
Published: September 2008

The production of ethylene by xylem tissues of Pinus radiata was monitored throughout the year. Statistically, significantly greater quantities of ethylene were produced during the winter by transition zones separating sapwood from heartwood than by transition zones during the rest of the year and by middle and inner sapwood during the entire year. Ethylene (5 ppm in air), but not carbon dioxide (27.5% in air), stimulated the production of pinosylvin in sapwood blocks. Phenol synthesis appeared to be preceded by desiccation during both heartwood formation and wound response. Tests with cycloheximide indicated that transition zones are capable of protein synthesis. It was suggested that the auxin-ethylene balance could contribute to quantitative and seasonal differences in ethylene production between the wound and senescent responses (heartwood formation). These and other results suggest that (i) ethylene is involved in stimulation of respiration and phenol synthesis during the wound and senescent responses of xylem tissues of this species, and (ii) heartwood formation takes place mainly in the dormant season during increased metabolic activity in the transition zone.
Genera coelomycetum. IX. Brycekendrickia gen. nov. and Vasudevella
Authors: Raj T. R. Nag
Published: September 2008

Brycekendrickia gen. nov. and B. indica sp. nov. are described. Revised descriptions of Vasudevella and its type species V. sporoboli are provided.
Benzyladenine effects on cell separation and wall metabolism
Authors: Halperin W. , Minocha S.
Published: September 2008

Cytokinins cause a failure of cell separation from primary explants cultured in agitated liquid media, as well as a variety of other phenotypic effects which are associated with alterations in wall metabolism. Using several different dicotyledonous species, a quantitative investigation was made of cell-to-cell binding in relation to changes in several relevant wall enzymes. Alterations in carbohydrate-degrading enzymes may not be responsible for the failure of cell separation since benzyladenine enhances rather than inhibits wall cellulase, and possibly also pectinase, activity. Wall acid phosphatase, an enzyme circumstantially associated with degraded wall regions of cultured cells, is also strongly promoted by benzyladenine. However, benzyladenine reduces the activity of calcium-chloride-extractable wall peroxidase 25 to 50% within 24 h after treatment. The reduction in salt-extractable peroxidase activity occurs whether or not there is concomitant auxin-induced growth, and may be associated with the synthesis of lignin.
Development of Cronartium comandrae in Comandra umbellata
Authors: Tainter F. H.
Published: September 2008

Infection of bastard toadflax by aeciospores of the comandra rust fungus appeared to occur through stomata. Within 3–4 days substomatal hyphae began ramifying into intercellular spaces between mesophyll cells. On the 5th day small chlorotic spots were visible with a 10 × hand lens and within 9 days, yellow uredial pustules were visible to the unaided eye. Uredia maturation proceeded via a palisade-like arrangement of cells to form basal cells, uredial initials, stalk cells, and urediospores, successively. By the 5th day haustoria began forming and by the 9th day were numerous, developing into a variety of sizes and shapes. Several layers of immature urediospores were also produced. By the 20th day host mesophyll cells became slightly compacted in the vicinity of the pustule and intercellular spaces were packed with fungal mycelium. After 25 days, the host cells in the base of the pustule became visibly disorganized and a central core of hyphae had developed in the base of most pustules, severely misshaping some host cells. Between 25 and 28 days most pustule membranes had ruptured and urediospores were liberated. Telia began to form in the former uredia by the 32nd day after inoculation.