bluuebunny/crossref_metadata_2025 huggingface dataset:
Absorption, translocation et métabolisme du chlorure de (2-chloroéthyl) triméthylammonium-1,2-14C chez l'orge d'hiver (Hordeum vulgare)
Authors: Belzile L. , Paquin R. , Willemot C.
Published: September 2008

The compound (2-chloroethyl) trimethylammonium chloride-1,2−14C (CCC) is weakly metabolized by winter barley (Hordeum vulgare L., var. Dover), 0.3% of the intital radioactivity being found in the choline moiety of phosphatidyl choline. Traces of radioactivity are also present in choline and in other unidentified compounds soluble in ethanol.CCC is more rapidly absorbed by the roots than by the leaves of winter barley and preferentially accumulates in the meristematic tissues.
In vitro studies on the induction of sporogenous tissue on leaves of cinnamon fern. I. Environmental factors
Authors: Harvey William H. , Caponetti James D.
Published: September 2008

Intact, set III, cinnamon fern cataphyll and frond primordia, which were shown to have no predisposition to fertility in situ, produced sporangia when excised and cultured under sterile conditions in Knudson's medium supplemented with various levels of sucrose and maintained on 11 different regimens of light, darkness, and temperature for 10 weeks. Increasing levels of sucrose resulted in increased fertility under all environmental conditions, but the highest percentage of fertility was obtained under conditions of continuous dark at 26 °C. As the length of the light phase of the photoperiods decreased, a progressive increase in induction of fertile leaves was observed, suggesting that periods of long light exposure are inhibitory to the initiation of sporangia. Conversely, as the light intensity was increased, an inhibition of sporophyll differentiation occurred. Sporangia excised from dark-induced sporophylls and cultured in the light produced viable spores which germinated yielding haploid gametophytes that ultimately produced sporophytes.
Use of cellulase and hemicellulase for the separation of Phytophthora cactorum oospores from mycelium mats
Authors: Sneh B.
Published: September 2008

Degradation of Phytophthora cactorum hyphal cell walls in mycelial mats was effected by incubation in a mixture of cellulase and hemicellulase for 7 days; fragments of homogenized mycelium were degraded after only 2 days. Oospore suspensions free from debris were obtained from the enzyme-treated cultures by washing them through nylon nets.
Genera coelomycetarum. VII. Cryptocline Petrak
Authors: Morgan-Jones G.
Published: September 2008

The genus Cryptocline Petrak is redescribed. Fourteen species are accepted, of which 10 are illustrated. Cryptocline nobile (Sacc.) Arx and C. proquinqua (Bubák and Vleugel) Arx are excluded from the genus while Rhabdogloeum hypophyllum D. E. Ellis and Gill is transferred to it.
Growth requirements and development of Cypripedium reginae in axenic culture
Authors: Harvais Gaëtan
Published: September 2008

In preliminary studies of terrestrial orchids of the Thunder Bay region Cypripedium reginae showed greatest promise as a species for the investigation of the effects of temperature, light, and nutrients. The orchid was grown from seed in sterile cultures on agar slopes of media consisting of various combinations of minerals, sugars, casein hydrolysate, yeast extract, potato extract, the vitamins thiamine, pantothenic acid, and pyridoxine, and the aminopurines kinetin, kinetin riboside, 6(γ,γ-dimethylallylamino)purine, and zeatin.Better germination and growth occurred at 25 °C vs. 15 °C. Germination was better in the dark than in the light. The young protocorms are adversely affected by light until a crucial stage of development is reached. Premature exposure to light, even at the low intensity of 70 lm/ft2, caused mortality.There was no germination on sterile-distilled-water agar or on mineral media alone. Mineral–sugar media produced fairly healthy plantlets; better results were obtained with sucrose, dextrose, and fructose, respectively. Cypripedium reginae was highly intolerant of the casein hydrolysate and yeast extract supplements. Potato extract at 10% of the original concentration was very beneficial.In some cultures the presence of ammonium ions could be responsible for a marked enhancement of growth (and a slight stimulation of germination irrespective of the presence of sugar). The right nitrate/ammonium ratio may be critical. Low levels of nitrate or high levels of chloride or both hindered responses to iron supplements. Also, C. reginae may have a low calcium requirement.The effects of the three vitamins were restricted to the leaves, causing them to broaden to natural proportions while those in the controls remained spindly. Thus, C. reginae may be heterotrophic for those vitamins.There was no morphogenetic response to the four aminopurines. They impeded growth equally in the light as in the dark.
In vitro studies on the induction of sporogenous tissue on leaves of cinnamon fern. II. Some aspects of carbohydrate metabolism
Authors: Harvey William H. , Caponetti James D.
Published: September 2008

Since previous studies indicated a requirement for high levels of exogenous sucrose for induction of sporogenous tissue on excised set III leaves of cinnamon fern, the initial part of this study was performed to determine which hexose moiety of sucrose would serve as the more active substrate for sporangial induction. Glucose was found to be preferentially used for sporophyll induction and resulted in more extensive development than was seen in those leaves grown on fructose. Endogenous carbohydrate levels were measured by gas–liquid chromatography. In decreasing order of quantity, freshly excised primordia contained xylans, sucrose, fructose, β-D-glucose, xylose, and α-D-glucose. In leaves cultured on medium with sucrose levels of 2, 4, 6, 8, and 10%, the highest levels of all endogenous carbohydrates studied were found in leaves grown on medium with 2% sucrose. The xylans accumulated in leaves grown on medium with all sucrose levels and the amounts present were generally above those of uncultured primordia. The xylans represented the highest quantities of the carbohydrates measured and appeared to be a major storage carbohydrate in both cultured and uncultured leaves. The concentrations of sucrose, on the other hand, generally declined and were, in all cases, below the amounts in uncultured primordia. Increasing levels of exogenous sucrose above 2% generally resulted in a decline in levels of the other internal carbohydrates after [Formula: see text] weeks of culture, but the respective quantities were generally above those of freshly excised primordia. Enzymatic analysis failed to reveal any starch in the leaves. It is suggested that although increasing sucrose levels resulted in an increase in the growth rate, it would appear that sucrose is important in sporangial induction because of some mechanism in addition to its effect on an increasing growth rate.
The incorporation of tritiated water into amino acids in the presence of urea by white spruce seedlings in light and darkness
Authors: Durzan D. J.
Published: September 2008

White spruce seedlings containing urease were exposed to 0.16 M urea for 4 h in continuous light. Seedlings accumulated total soluble nitrogen as amides and arginine, and increased their content of bound amino acid nitrogen. In darkness, total soluble nitrogen declined and the increase of total bound amino acids was not as great as in light. In both treatments, the fate of tritiated water was examined by recovery of nonexchangeable tritium from amino acids. As urea was consumed, more tritium was recovered from seedlings in light than in darkness. In both treatments tritium followed the nitrogen of urea and was bound covalently, initially in glutamic acid, and subsequently wherever an α-keto acid was a precursor for the synthesis of the corresponding amino acid, viz. alanine and aspartic acid. In light, tritium was recovered mainly from glutamic acid, followed by glutamine, and to a lesser extent by γ-aminobutyric acid. In darkness, while glutamic acid was prominent initially, more radioactivity was recovered from γ-aminobutyric and glutamic acids compared to glutamine and to the light treatment. Glutamic acid was the main bound amino acid containing covalent tritium.The occurrence of tritium at the α-carbon of glutamic acid was supported by transfer of this tritium after decarboxylation to γ-aminobutyric acid, and by conversion of bound glutamate-3H to radioactive pyrrolidone carboxylic acid during acid hydrolysis of protein.Although urea nitrogen contributed to arginine synthesis in light, no tritium was found in arginine nor its precursors in the ornithine cycle until later, when nearly all amino acids were radioactive. This is consistent with the absence of covalent binding of tritium in ureido precursors leading to arginine biosynthesis, and supports the idea that tritium did not readily follow the carbon of urea into covalent linkage.
Nitrogen metabolism of Picea glauca. V. Metabolism of uniformly labeled 14C-L-proline and 14C-L-glutamine by dormant buds in late fall
Authors: Durzan D. J.
Published: September 2008

In early fall, the high levels of free arginine nitrogen in spruce buds were eventually replaced by proline nitrogen, and in late spring, glutamine nitrogen accumulated. In late October when levels of free proline nitrogen were high, bud primordia from terminal shoots were excised and exposed to uniformly labeled 14C-L-proline and 14C-L-glutamine. The main early products from 14C-L-proline were Δ1-pyrroline-5-carboxylic acid, glutamic-γ-semialdehyde, and glutamic acid. Later products included glutamine, γ-aminobutyric acid, and to a much lesser extent pyrrolidone carboxylic acid, ornithine, and arginine. In protein, radioactivity was recovered from proline, glutamic acid, and hydroxyproline.Products from 14C-glutamine were mainly glutamic and α-ketoglutaric acid as well as proline, γ-aminobutyric acid, alanine, and pyrrolidone carboxylic acid. In protein, glutamic acid, aspartic acid, and proline contained carbon-14. Results indicated that proline and glutamine were related by their carbon metabolism through a common path involving glutamic acid. However, the main feature of glutamine metabolism was the removal of its α-amino and the amide nitrogen to yield α-keto acids especially α-ketoglutaric acid. The occurrence of α-ketoglutaramic acid could have accounted for succinamic acid and succinimide derived from 14C-L-glutamine.
Improved filtration techniques for the concentration and cytological preservation of microalgae for electron microscopy
Authors: Bisalputra T. , Cheng J. Y. , Taylor F. J. R. , Antia N. J.
Published: September 2008

A gentle filtration technique is described for concentration and fixation of phytoplankters directly on Millipore membranes, followed by subsequent removal of the membrane and embedment of the cellular material in epoxy resin. The technique shows excellent preservation of cell morphology, especially of fragile algal cells (dinoflagellates, zoospores, etc.), with little loss of material, and affords permanently fixed samples for both light and electron microscopy. It is ideally suitable for handling small amounts of algal cultures and for frequent sampling of such cultures in time-sequence studies. Adaptations of the technique are described which enable (1) high proportion of flagella preservation, (2) successful concentration of algal cells from water samples of low population density, and (3) convenient preparation of samples for "freeze-etching" or histochemical studies. A further application to scanning electron microscopy is described, where the replacement of Millipore membranes by Nuclepore filters affords the differentiation of nannoplanktonic cells from non-living debris and detritus, thereby holding promise for ecological studies of natural waters.
The effects of osmotic water potentials on Aphanomyces euteiches during zoosporogenesis
Authors: Hoch H. C. , Mitchell J. E.
Published: September 2008

Zoosporogenesis in Aphanomyces euteiches was inhibited by increasing the osmotic water potential (ψπ) of the wash solution used to induce asexual reproduction. Mycelial protoplasm did not differentiate into primary spores when exposed to osmotica of glucose, mannose, fructose, sorbitol, sucrose, KCl, CaCl2, and polyethylene glycol (PEG) 4000 of ψπ ≤ −5.0 bars. Primary spores were formed in these osmotica at ψπ ≥ −4.0 bars, but they were not extruded from the sporangia until the ψπ ≥ −3.0 bars. Active zoospores were observed only at ψπ ≥ −2.0 bars and were most abundant at ψπ ≥ −0.5 bars. Osmotica of mannitol, i-erythritol, glycerol, and i-inositol did not completely suppress zoospore formation until the ψπ ≤ −7.0 bars, and primary spore cleavage occurred at ψπ as low as −11.0 bars. PEG-6000 and PEG-20 000 prevented primary spore formation at ψπ below −3.0 bars and −0.5 bars, respectively. The ψπ and turgor pressure (ψp) of mycelia exposed to various water potentials were also determined and found not to differ greatly between the various osmotica. The ψπ of vegetative mycelia was found to be about −8.0 bars, while that activated to form primary spores in the basal salt wash solution was −3.0 bars. As the ψπ of the solution decreased, so did the ψπ of the mycelia until the two were equal to about −14.0 bars, thus creating a zero ψp of the mycelia. Mechanisms for asexual spore formation and discharge are also discussed.
Preliminary studies in the taxonomy of Danthonia in Canada
Authors: Baum B. R. , Findlay Judy N.
Published: September 2008

Representative Canadian herbarium material of Danthonia was studied morphologically and micromorphologically. Characters used by previous authors were reexamined. Among the new characters studied the lodicule patterns were found to be very useful for discrimination. Canonical analyses were performed excluding input of lodicule patterns, but with the incorporation of various other lodicule attributes. As a result, five species are recognized for Canada; a key and a map of distribution are given. An additional canonical analysis with the inclusion of latitude and longitude added as input has shown that the geographical factor is insignificant.
Regenerative studies on the detached leaves of Echeveria elegans. Regeneration and growth in leaves
Authors: Raju M. V. S. , Hines James E.
Published: September 2008

Detached leaves of Echeveria elegans Bgr. produce both roots and shoots. However, when their bases are severed, they tend to produce only roots. It was observed that roots had to be present on detached leaves, bases removed or not, in order to have an increase in size and also in dry weight. The growth in size was found to be due mainly to enlargement of cells, and the increase in dry weight was presumably due to maintenance of normal metabolic activity in the detached leaves. Thus detached leaves of E. elegans have a greater potential for growth than is normally realized by the leaves that are mature and still attached to the parent axis. The vigorously growing shoots seem to have an inhibitory influence on growth in the detached leaves. Roots on detached leaves, on the other hand, seem to play an important role not only in the delaying of senescence but also in reducing the inhibitory influence of shoots. Roots alone appeared to bring about "uncontrolled" enlargement of cells and consequently lesions were formed on the leaves, which finally died off. Thus growth, regeneration, and senescence in the detached leaves appear to be correlative phenomena.
Effect of oxygen concentration on the rates of photosynthesis and photorespiration of some higher plants
Authors: D'Aoust A. L. , Canvin D. T.
Published: September 2008

Carbon dioxide gas exchange of leaf material was studied in the light at different oxygen tensions for two CO2 concentrations, using an isotope technique. With bean, radish, and tobacco leaves in the leaf chamber, increasing the oxygen tension resulted in a significant alteration in the 14CO2/CO2 ratio of the gas mixture leaving the leaf chamber as compared to that offered to the leaf material. On estimating the rates of “true’ and apparent photosynthesis it was found that below 5% oxygen concentration the rates were not significantly different. However, increasing the oxygen concentration of the gas mixture resulted in a proportional decrease in the rates of true and of apparent photosynthesis. The increasing oxygen tension also resulted in proportional increases in the CO2 evolution (true photosynthesis minus apparent photosynthesis). The percentage inhibition of apparent photosynthesis was greater at low carbon dioxide concentration, while the inhibition of true photosynthesis was not as sensitive to the carbon dioxide level. The inhibition of apparent photosynthesis was not entirely attributable to the increased photorespiration but was roughly equally divided between an inhibition of true photosynthesis and a stimulation of CO2 evolution in the light.However, with corn leaf material, there was no effect of oxygen concentration on both the rates of true and apparent photosynthesis; also, no large CO2 evolution could be detected as emerging from leaf in the light at any of the oxygen concentrations tested.
Influence de phénomènes d'antagonisme entre organes et entre régulateurs sur le développement floral de bourgeons cotylédonaires chez le Scrofularia arguta
Authors: Miginiac Emile , Lacombe Nicole
Published: September 2008

The influence of various correlations and a few growth regulators (auxin, abscissic acid, and kinetin) on vegetative or floral development of cotyledonary buds is studied on plants or plant fragments cultured in vitro. It is shown that the terminal bud inhibits growth and stimulates flowering, whereas "non-absorbing roots" inhibit floral development; if the terminal bud is present, the roots are inactive. This antagonism between organs can be simulated by replacing the terminal bud by an auxin or abscissic acid treatment and the roots by a kinetin treatment. The two groups of substances show antagonistic actions on the nature of cotyledonary bud development. Flowering or non-flowering, then, depends on the balance of concentration of these two groups of substances in the culture medium.
Control of cambial activity in roots of turnip (Brassica rapa)
Authors: Peterson R. L.
Published: September 2008

The physiological control of cambium activity in seedling roots and isolated cultured root tips of turnip was investigated. In seedlings, excision of the root tip had no effect on root cambial activity while excision of the shoot (including cotyledons) resulted in a dramatic reduction in both cambial derivatives and secondary xylem elements. Removal of one or two cotyledons also reduced root cambial activity. An investigation of the control of cambial activation in cultured first-transfer root tips of turnip showed that a combination of an auxin, a cytokinin, sucrose, and myoinositol was necessary for maximum radial growth of these excised root tips. The deletion of any one of these substances resulted in a reduction in cambial activity. Likewise, root tips treated with any one of these growth regulators alone showed little cambial activation. The present results are compared to results obtained by earlier workers using other genera of plants, and it is shown that the control of cambial activity is similar to that described for radish roots but differs from the results obtained with pea roots.
Conidial state of Poronia punctata
Authors: Stiers D. L. , Rogers J. D. , Russell Dorothy Watts
Published: September 2008

Conidium ontogeny of Poronia punctata is described. The conidium wall is continuous with the conidiogenous cell wall, i.e., is holoblastic in origin. Secession of the conidium involves rupture of a highly developed cross wall between conidium and conidiogenous cell.
Observations of thraustochytriaceous (Phycomycetes) and labyrinthulid (Rhizopodea) ectoplasmic nets on natural and artificial substrates—an electron microscope study
Authors: Perkins Frank O.
Published: September 2008

The ectoplasmic net ultrastructure of five thraustochytrids and labyrinthulids (Labyrinthula algeriensis; L. minuta; T-20, an undescribed thraustochytrid; Schizochytrium aggregation; and Thraustochytrium motivum) is described for cells grown on different microorganisms, metazoan cells, and spermatophyte cells. Net elements did not appear to actively penetrate animal cells, but a mat was formed on the surface of the food cells, lysis resulted, and net elements intermingled with the organelles, followed by food cell digestion. A similar sequence of events resulted in digestion of plant cells after penetration of the food cell wall at selected sites. The highly resistant sporopollenin layer of pine pollen was digested and penetrated by T. motivum and S. aggregatum. Internal membrane arrays of net elements in all species were found to be markedly larger than in cells grown on artificial media, thus suggesting a possible role in digestion of the food cells.The fine structure of ectoplasmic nets formed on thin formvar rafts was also examined in whole-mount preparations. The cells which use the nets in motility formed net-like arrays which were more nearly symmetrically arranged around the cells than in those species which were not motile (S. aggregatum and T. motivum). The latter species extended nets from one side of the cell and generally formed less periodically structured, smaller mesh nets around one or several amorphous, major net elements.
The bacteria in sapwood, wetwood, and heartwood of trembling aspen (Populus tremuloides)
Authors: Knutson Donald M.
Published: September 2008

Bacteria (Erwinia, Bacillus) were consistently isolated from all samples of aspen sapwood and heartwood. In wetwood zones (water-soaked xylem tissue) or discolored heartwood, large populations often occur. No organisms unique to wetwood were isolated. Wetwood probably is formed by nonmicrobial means and, once formed, merely supports large populations of indigenous bacteria.
Palynology of six sections of Late Quaternary sediments from the Old Crow River, Yukon Territory
Authors: Lichti-Federovich Sigrid
Published: September 2008

The Old Crow Plain, northern Yukon Territory, Canada, is a large flat lowland consisting of basin-fill sediments of Late Quaternary age. The modern Arctic treeline passes across the northern tip of the lowland, and much of the vegetation consists of tundra and shrub tundra, with scattered groves of spruce mainly on alluvial deposits. Steep scarps have been exposed by the downcutting of the Old Crow River in these basin-fill sediments, and good exposures of Late Quaternary sediments are available for investigation. Samples from six of these exposures were analyzed for pollen. Although many parts of the sections were barren, it has been possible to derive pollen diagrams with discrete pollen zones for the six sections, and four pollen assemblage types have been identified. Their occurrence in the stratigraphie sequence suggests the following pattern of pollen stratigraphy: the lowermost sedimentary units, probably deposited early in the interstadial following an Early Wisconsin glaciation, are of pollen assemblage types III (Glumiflorae–herb) or IV (Betula–herb), both indicative of tundra vegetation; the middle levels of the sediment show, consistently, pollen spectra of type II (Picea–Betula–Glumiflorae–herb), indicating forest groves with tundra, quite similar to the modern vegetation. The sediment underlying the Upper Glaciolacustrine Unit (correlative, according to Hughes (1969), with the Classical Wisconsin Stadial) yields pollen assemblage type III (Glumiflorae–herb), which is interpreted as indicating a rich and varied tundra. These vegetation reconstructions are consonant with a tentative palaeoclimatic interpretation in terms of a tripartite interstadial climate showing severe tundra climate – milder forest or forest–tundra climate – severe tundra climate. Two of the sections have incomplete pollen stratigraphy for the uppermost postglacial silts and peats. They suggest that vegetation similar to the present day became established in the Old Crow Plain in mid-postglacial time.
Foliicolous bryophytes and lichens of Thuja plicata in western British Columbia
Authors: Vitt Dale H. , Ostafichuk Michael , Brodo Irwin M.
Published: September 2008

Four species of mosses, all in the genus Orthotrichum; 1 species of hepatics; and 16 species of lichens compose the foliicolous bryophyte and lichen flora of Thuja plicata L. leaves in certain areas of western British Columbia. This is the first report of foliicolous mosses and hepatics for North America, north of the tropical and subtropical regions of the southeastern United States. The taxonomy of the four species of Orthotrichum is discussed and a key given differentiating the species.All of the species that have been found on Thuja leaves except perhaps Catillaria bouteillei are facultative foliicolous species and occur on leaves, only in scattered areas of northwestern North America. Two taxa of lichens, Catillaria bouteillei (Desm.) Zahlbr. and Cetrelia cetrarioides (Del. ex Duby) W. Culb. & C. Culb. (perlatolic acid strain) are reported as new to Canada.
CO2 assimilation by Dryas integrifolia on Devon Island, Northwest Territories
Authors: Mayo James M. , Despain Don G. , van Zinderen Bakker Jr. Eduard M.
Published: September 2008

In situ measurements of CO2 assimilation by Dryas integrifolia at different stages of development and under different environmental conditions were made on Devon Island, Northwest Territories. Dryas can fix CO2 in excess of respiration over a 24-h period under conditions of clear nights and cloudy days. The maximum net assimilation rate measured was 4.2 mg g−1 dry weight h−1. The maximum amount of CO2 fixed in 24 h was 61.54 mg g−1 dry weight. Maximum net assimilation occurred at 8 to 10 °C leaf temperatures. Positive net assimilation occurred at 1 °C leaf temperature. Light compensation was shown to be less than 0.04 langley min−1. Leaf temperatures were always greater than ambient. The maximum leaf temperature measured was 39 °C. Net assimilation rates appear to decrease as the season progresses.
Differential effects of cholesterol in mating thalli of Pythium sylvaticum and Phytophthora capsici
Authors: Pratt R. G. , Mitchell J. E.
Published: September 2008

Hyphae of male and female isolates of Pythium sylvaticum grown from inoculum blocks with and without 0.01 g/liter cholesterol met and produced sexual unions in water agar. Fewest oospores formed when sterol was omitted from both male and female sides. Sterol added to the male side only did not cause a significant increase in percentage of mature oospores formed in sexual unions, but addition of sterol to the female side resulted in greatly increased numbers of oospores. When two pairs of isolates were mated and cholesterol was added to both sides, a further increase in oospore formation occurred that was significant at the 5% level with one pair and at the 1% level with another pair. These results are viewed as a dosage effect due to the relative amounts of sterol carried in the male and female game-tangia and not to a specific effect on either sex. Rare mature oospores were found in single cultures of the female type isolate of P. sylvaticum. Oospore formation in crosses of isolates N14 and N58 of Phytophthora capsici increased significantly when either isolate was grown from a medium containing 0.03 g/liter cholesterol. These results are viewed as effects of bisexual mating by both Phytophthora isolates.
An ultrastructural and Nomarski-interference study of the sperms of barley
Authors: Cass David D.
Published: September 2008

Male gametes of barley are small cells with conspicuous nuclei and compact cytoplasm. The cytoplasm is limited by a unit membrane. Between sperm and vegetative cell unit membranes is a thin, relatively homogeneous region which failed to stain with common cell wall specific reagents at the light microscope level. Cytoplasmic contents include mitochondria, ribosomes, dictyosomes, endoplasmic reticulum, and microtubules. Microtubules occur nearly around the entire periphery of a transected sperm, sometimes occurring in clusters of up to 16 tubules. Their chief orientation is longitudinal. No plastids or plastid-like organelles were observed. Chromatin in the nucleus is condensed; when present, there are two nucleoli. Living sperms observed with Nomarski-interference optics exhibited marked cytoplasmic activity, but no directional motility. Observed transitions from spindle-shaped to more spherical sperms could be facilitated by changes in disposition of sperm microtubules.
Megasporogenesis and megagametogenesis in Pelargonium × hortorum
Authors: Tsai Annie H. , Harney Patricia M. , Peterson R. L.
Published: September 2008

The ovary of Pelargonium × hortorum contains five pairs of superposed ovules in five locules. These ovules are bitegmic and crassinucellar and the upper ovule of each pair is campylotropous while the lower one is anatropous. A single archesporial cell functions directly as the megaspore mother cell. Meiotic division of the megaspore mother cell results in the formation of a linear tetrad of megaspores of which the chalazal megaspore is functional. Embryo sac development is of the polygonum type. Rapid degeneration of the three antipodals occurs followed by the fusion of the two polar nuclei. Therefore, the mature embryo sac contains the egg, the two synergids, and the fused polar nucleus. Double fertilization takes place. Ninety-two percent of the fertilized ovules of P. × hortorum cv. ‘Purple Heart’ are found in the upper position.The two integuments are initiated before the differentiation of the archesporial cell. Cells of the outer layer of the outer integument and the inner layer of the inner integument deposit tannins. The nucellus develops through divisions of the parietal cells of the nucellar epidermal cells.
Levels of polyploidy in four vegetation types of southwestern British Columbia
Authors: Pojar Jim
Published: September 2008

Chromosome counts were made for the angiosperm species of five sample sites representative of four vegetation types in southwestern British Columbia. Levels of polyploidy were calculated for both the flora and vegetation of each of the sites. It is proposed that the differences in polyploid levels between the sites are related primarily to the increased likelihood of formation and selective advantage of allopolyploids in chronically unpredictable physical environments.
The effect of light intensity on tumorigenesis in a Nicotiana amphiploid
Authors: Ames Ira H.
Published: September 2008

Young seedlings of the tumor-prone amphiploid Nicotiana suaveolens × N. langsdorffii were grown aseptically on nutrient medium under either 2000, 1000, or 500 ft-c of illumination. The incidence of tumor formation was scored at regular intervals beginning 17 days after the seeds had been sown. The rate of tumorigenesis was significantly reduced in those plants that were exposed to either 1000 or 500 ft-c of illumination. These seedlings were also taller and heavier than those grown under 2000 ft-c.
Cytochemical differentiation between ATPase and fructose-1,6-diphosphatase in dry peanut cotyledons
Authors: Grove Stanley N. , Ory Robert L.
Published: September 2008

Two acid phosphatase activities can be differentially localized by cytochemistry in dry peanut cotyledons. Adenoside triphosphatase activity is localized at the plasma membranes but not found in plasmodesmata or protoplasmic components. Fructose-1,6-diphosphatase activity is localized in the cytoplasmic matrix to the exclusion of plasma membranes, lipid bodies, aleurone grains, and other organelles.
Floral development of Potamogeton densus
Authors: Posluszny U. , Sattler R.
Published: September 2008

The floral appendages of Potamogeton densus are initiated in an acropetal sequence. The first primordia to be seen externally are those of the lateral tepals, though sectioning young floral buds (longitudinally, parallel to the inflorescence axis) reveals initial activity in the region of the lower median (abaxial) tepal and stamen at a time when the floral meristem is not yet clearly demarcated. The lateral (transversal) stamens are initiated simultaneously and unlike the median stamens each arises as two separate primordia. The upper median (adaxial) tepal and stamen develop late in relation to the other floral appendages, and in some specimens are completely absent. Rates of growth of the primordia vary greatly. Though the lower median tepal and stamen are initiated first, they grow slowly up to gynoecial inception, while the upper median tepal appears late in the developmental sequence but grows rapidly, soon overtaking the other tepal primordia. The four gynoecial primordia arise almost simultaneously, although variation in their sequence of inception occurs. The two-layered tunica of the floral apices gives rise to all floral appendages through periclinal divisions in the second layer. The third layer (corpus) is involved as well in the initiation of the stamen primordia. Procambial strands develop acropetally, lagging behind primordial initiation. The lateral stamens though initiating as two primordia each form a single, central procambial strand, which differentiates after growth between the two primordia of the thecae has occurred. A great amount of deviation from the normal tetramerous flower is found, including completely trimerous flowers, trimerous gynoecia with tetramerous perianth and androecium, and organs differentiating partially as tepals and partially as stamens.
Studies in the Arundinelleae (Gramineae). XV. Taximetrics of leaf anatomy
Authors: Li Y-H. C. , Phipps J. B.
Published: September 2008

Taximetric studies on 106 operational taxonomic units (OTU's) of the tribe Arundinelleae (Gramineae)—most of the non-Loudetia species—using 81 anatomical characters, resulted in a classification resembling the traditional ones in only a very general way. This lack of congruence, if the reproductive morphology is to be considered the key to Arundinellean classification, is indicative of considerable convergent evolution of leaf anatomical character suites. Nevertheless, groupings of 22 out of 41 Arundinella OTU's studied remain together, as do 6 out of 8 Trichopteryx, all the Danthoniopsis, sensu stricto, and many of the tristachyoids. However, a large and intermixed grouping containing the other tristachyoids, remaining Arundinella species and Trichopteryx, the few Loudetia species included in the study, other danthoniopsoids, and most Loudetiopsis, sensu lato, occurs. Jansenella is shown to be extremely isolated, though Gilgiochloa is very close to Danthoniopsis, sensu stricto. Some of the characters most responsible for the variation encountered are the amount and the distribution pattern of the sclerenchyma, the occurrence and the arrangement of the colorless parenchyma, the presence of distinctive cells, and some other characters which are related to size, such as the prominence of a keel, the presence and the height of the ribs, etc.
Antifungal activity of Rhizobium
Authors: Drapeau R. , Fortin J. A. , Gagnon C.
Published: September 2008

Antifungal activity of three different Rhizobium isolates was tested against eight different fungi. Some of these fungi are potential phytopathogens on legumes. Inhibition zones were observed in several cases. Similar results were obtained with the cell-free extract of the media on which Rhizobium had been grown.
The long-term fate and distribution of 14C photoassimilated by young white pines in late summer
Authors: Ursino D. J. , Paul J.
Published: September 2008

In early September after shoot elongation and needle expansion had terminated, pine plants (Pinus strobus L.) in their third year of growth were permitted to photoassimilate 14CO2. At intervals of time ranging from [Formula: see text] to [Formula: see text] months, the distribution of 14C within the plants was determined. Within the first 48 h about 40% of the photoassimilated 14C was lost from the plant through respiration and of the retained 14C, over 50% was found in the root, a value equivalent to about a third of the total 14C activity initially assimilated. Despite continued losses of 14C from the pines, about 30% of the initially assimilated 14C was still present [Formula: see text] months later. Evidence for remobilization of 14C into the following year's shoot growth is also provided.
The structure of protein bodies in Cucurbita maxima cotyledons
Authors: Lott John N. A. , Vollmer Catherine M.
Published: September 2008

The results of this freeze-etching study of imbibed seeds confirm the findings of an earlier study on the structure of protein bodies in the cotyledons of dormant squash seeds. The cotyledon mesophyll cell protein bodies were found to have at least four components, which are the proteinaceous matrix, the protein crystalloid, the soft globoid, and the globoid crystal.
Nonspecificity of the necrosis-inducing toxin of Sclerotium bataticola
Authors: Chan Y. H. , Sackston W. E.
Published: September 2008

Sclerotium bataticola produces a translocatable toxin which induces necrotic spotting in sunflower leaves. The toxin is not host specific, and does not induce symptoms on all susceptible host species. Virulence of four isolates of S. bataticola is not correlated with their toxin production in culture.
Mineral nutrition of Pythium marinum, a marine facultative parasite
Authors: Kazama Frederick Y. , Fuller Melvin S.
Published: September 2008

Pythium marinum Sparrow, isolated from lesions on Porphyra miniata, required Na+, Ca2+, and Mg2+ in quantities far exceeding those reported to be required by terrestrial species of Pythium. Unlike most of its terrestrial counterparts, P. marinum required alkaline pH values for good growth, with a pH of 7.8 providing maximum growth under the conditions examined. The requirement for large amounts of Na+ ions appeared to have a specific nutritional basis rather than a purely osmotic function. Growth at various temperatures indicated that the fungus is a facultative psychrophile with the optimum growth temperature between 15 and 20 °C. The nutritional data show that P. marinum is able to grow in a wide range of salt concentrations and is well adapted to the marine environment.
Resistance and virulence in the Avena: Puccinia coronata host–parasite system in Kenya and Ethiopia
Authors: Martens J. W. , McKenzie R. I. H.
Published: September 2008

Crown rust of oats is widespread on wild and cultivated oats in Kenya and Ethiopia. The six oat species in the area have very little resistance to crown rust, which has a wide virulence range, much wider than required for local survival. Thirteen physiologic races were identified using 10 single resistance Pc gene line cultivars. Kenya and Ethiopia appear to have distinct pathogen populations with only a few races in common.
Effects of ozone on bean rust Uromyces phaseoli
Authors: Resh H. M. , Runeckles V. C.
Published: September 2008

Diurnal exposure to ozone at low concentrations reduces the size of primary uredia of bean rust on bush bean, increases their number, and leads to secondary pustule formation. Infection does not protect the host tissues from ozone injury, since such injury can be observed immediately adjacent to pustules. Similarly, infection does not retard the enhanced rate of senescence induced by ozone treatment.
Growth kinetics of Marquis wheat. IV. Temperature dependence
Authors: Macdowall F. D. H.
Published: September 2008

Earlier described data from this laboratory were subjected to primary growth analysis. The plants had been grown in constant conditions of light intensity (200 to 2500 ft-c) and temperature (10° to 30 °C) at five different settings each. Multiple temperature optima were revealed and interpreted. The computed maximum plant growth coefficient was highest in value at 25 °C (plant kmL = 0.44 day−1) and secondarily so at 15 °C, but at the experimental light intensities the plant growth coefficient was maximal at 15 °C. The higher temperature optimum was characteristic of roots and "stems" (stem plus leaf sheaths) whose growth coefficients displayed a prominent peak at 25 °C (root kmL ~ 0.8 day−1, "stem" kmL = 0.4 day−1). This optimum was shifted downward with decreasing light intensity until temperature insensitivity was attained at low light intensity. The low-temperature optimum at 15 °C was principally displayed by leaf blades (lamina kmL = 0.47 day−1) whose computed maximum growth coefficient also showed a secondary maximum at 25°, but the 15 °C peak was the only one evident at low light intensities. It was tentatively concluded that the 25 °C temperature optimum was that of net translocation, and that the 15 °C temperature optimum was that of net photosynthesis in which photosynthesis was primarily balanced by photorespiration in wheat. The differential growth of the organs represented their relative sink strengths for attracting growth substrate, as dependent on light intensity and temperature. The availability of photosynthate was considered to be the dominating factor in the kinetics of growth free from inorganic limitations. When there was very little photosynthate the tissues benefited from translocation on a "first come first serve" basis. The high values of kmL pushed the absolute maximum plant growth coefficient, kM, of Marquis wheat toward 0.5 or 50% per day, and the basis of the advantage over previous approximations must be elucidated by further experiments. The computed relative efficiency of the use of photosynthate for growth was temperature dependent, but its value at optimum temperature was similar to previous estimates.
Morphological variation of Dicranidion fragile and D. inaequalis in culture
Authors: Butterfield Winifred
Published: September 2008

Cultural studies of single conidium isolates of strains of Dicranidion fragile Harkness, 1885, and Dicranidion inaequalis Tubaki and Yokoyama, 1971, revealed extensive variation in conidial morphology. Dicranidion inaequalis is placed in synonymy with D, fragile, because both produce stauroconidia with symmetrical and asymmetrical basal cells by single conidium isolates. The production of phragmoconidia as the variation or mutation of stauroconidia is discussed.
Formation of p-hydroxybenzoic acid from phenylacetic acid by Poria weirii
Authors: Li C. Y. , Lu K. C. , Trappe J. M. , Bollen W. B.
Published: September 2008

Phenylacetic acid is known to inhibit growth of Poria weirii cultures at concentrations of 2.0 mM but not at 0.5 mM. In this study, the compound at the lower concentration was metabolized by the fungus by degradation to noninhibitory p-hydroxybenzoic acid and an unknown compound.
Environmental control of gametogenesis in Laminaria saccharina. II. Correlation of nitrate and phosphate concentrations with gametogenesis and selected metabolites
Authors: Hsiao Stephen I. C. , Druehl Louis D.
Published: September 2008

The gametophyte growth, morphology, gametogenesis, and metabolites of Laminaria saccharina (L.) Lamouroux were studied in different cyncentrations of nitrate and phosphate in axenic culture, using a synthetic seawater medium under optimal light and temperature conditions.Nitrate and phosphate were required for the various stages of gametophyte development and gametogenesis. Under nitrate and phosphate concentrations optimal for growth and gametogenesis, maximum quantities of DNA, RNA, protein, and carbohydrate, and low quantities of lipid were produced. Further, nutrient concentrations which gave rise to the greatest fertility also gave rise to the highest ratios of RNA/DNA and protein/RNA.Antheridial production occurred over a wider range of nitrate and phosphate concentrations than oogonial production. Further, percentage fertility was greater for the male gametophyte. This indicated that the female gametophyte was the limiting agent in sexual fusion.
The development of the embryo sac of sunflower Helianthus annuus after fertilization
Authors: Newcomb William
Published: September 2008

The degeneration of one synergid denotes the initiation of embryo and endosperm development in the embryo sac of sunflower Helianthus annuus L. The other synergid, the persistent synergid, is present until the late globular stage of embryogenesis. The primary endosperm nucleus divides before the zygote nucleus forming a coenocytic nuclear endosperm. When about eight endosperm nuclei are present during the early globular stage of embryogenesis, endosperm wall formation starts at the micropylar end of the embryo sac. The walls continue to grow toward the chalazal end of the embryo sac apparently as a result of the activity of Golgi located at the tips of the growing walls. Most endosperm wall formation is not associated with a mitotic spindle apparatus in sunflower. The suspensor of the embryo consists of a large basal cell during the proembryo stages, a single row of cells during the early globular stages, and at the late globular stage a double tier of cells near the radicle end of the embryo and a single row at the micropylar end of the embryo sac. Occasionally embryo development occurs in the absence of endosperm when only single fertilization has taken place. The development and nutritional implications of post-fertilization events in the sunflower embryo sac are discussed.
Studies in the Alismataceae. IV. Developmental morphology of Ranalisma humile and comparisons with two members of the Butomaceae, Hydrocleis nymphoides and Butomus umbellatus
Authors: Charlton W. A. , Ahmed A.
Published: September 2008

The development of the foliage leaf bearing axes in Ranalisma humile (Kunth.) Hutch. and Hydrocleis nymphoides Buch. is similar in that both show sympodial development, each branch of the sympodium terminating in an inflorescence; in Butomus umbellatus L. the inflorescence is lateral and the vegetative axis is monopodial.Inflorescences of Ranalisma can adopt a horizontally growing pseudostolon form in which floral meristems are formed but abort at an early stage; there is no basic difference between the organ complements of the pseudostolon and the erect inflorescence.Inflorescences of Hydrocleis and Ranalisma have similar developmental patterns. In both, the main axis terminates in a floral primordium while a large bud is developed in the axil of the first of two bracts below the flower. The lateral bud in Hydrocleis develops into a sympodial bud complex consisting of flowers, a vegetative bud, and an inflorescence branch which repeats the pattern of development; in Ranalisma the lateral bud gives rise only to a vegetative bud and an inflorescence branch. Ranalisma appears to possess a reduced form of the kind of inflorescence development found in Hydrocleis.The inflorescence of Butomus also terminates in a flower. It has three bracts, each subtending a set of multiple axillary buds. Each individual bud develops into a sympodially arranged set of flowers.Previously proposed isolation of Butomus from other Butomaceae and Alismataceae is further emphasized by developmental data. Ranalisma provides a connecting link between Alismataceae and the Butomaceae excluding Butomus (i.e. the Limnocharitaceae of some authors).