摘要:

The uptake of14C-labeled glucose, fructose, and sucrose intoNitella flexilishas been investigated by varying concentrations of sugars, by the use of competition experiments, by the use of inhibitors, and by varying conditions of temperature. The kinetic studies and the complex interaction between the sugars were characteristic of a carrier-mediated system maintained by metabolic energy. Glucose and fructose appear to have different sites of entry though each can influence the other. It is suggested that sucrose is hydrolyzed at the plasmalemma, glucose and fructose then entering the cells.

ISSN:0008-4026    

DOI:10.1139/b74-001

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The chromosome number ofRosellinia mammiformisisn = 6. Ascospores are uninucleate when formed, becoming binucleate by mitosis. One of the nuclei degenerates; maturing ascospores are uninucleate. Ascospores show apical appendages that are proliferations of the outermost wall or perispore. The chromosome number ofRosellinia aquilais tentativelyn = 6. Ascospores are at first uninucleate, becoming binucleate by a mitosis. One of the nuclei degenerates and is often cut off in an appendage. Maturing ascospores are uninucleate and show two types of appendages. Secondary appendages are formed from the perispore. Primary appendages are cut off from the spore body by a septum and are surrounded by the secondary appendage. In addition, a double primary appendage, part of which probably functions to trap a degenerating nucleus, is described. The significance of these results is discussed.

ISSN:0008-4026    

DOI:10.1139/b74-002

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The perfect state ofDiplodia tumefaciens(Keissleriella emergens(Karsten) Bose) is described from the infected roots ofPopulus balsamifera.

ISSN:0008-4026    

DOI:10.1139/b74-003

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

A study was conducted in 1971 to estimate the degree of genetic control on the characters of cone morphology of white spruce (Picea glauca(Moench) Voss) from two areas of central Newfoundland and to determine whether these characters were associated with phenotypic superiority in growth. Hierarchical sampling was done, selecting two locations, two populations at each location, five trees in each population, and 20 cones from each tree. Ten characters were studied. Statistical analysis techniques used were calculation of repeatability as an estimate of heritability, hierarchical analysis of variance, and comparison of the populations of "ordinary" and "plus" trees, using Student's ‘t’ and Snedecor's 'F' tests.The results indicate that most of the 10 characters studied are under strong genetic control but these characters are not associated with phenotypic superiority in growth.

ISSN:0008-4026    

DOI:10.1139/b74-004

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The integrity of the local-lesion technique in producing genetically homogeneous isolates of tobacco mosaic virus fromNicotiana glutinosahas been verified using strains doubly labeled with genetic markers governing symptomatology and host range.

ISSN:0008-4026    

DOI:10.1139/b74-005

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Somatic and genetic effects of incorporated strontium-90 and cesium-137 in the small cruciferArabidopsis thaliana, race Estland, were studied. The uptake and distribution of the radionuclides in the treated plants (M1) and their progeny (M2) were determined and the approximate radiation dose received was calculated.A significant increase in plant height and acceleration of floral initiation in the M1plants was observed. This was most likely a radiation effect rather than an ionic (or chemical) effect. The early flowering was consistently observed in several subsequent tests with acute gamma-ray seed treatment at 0.3 krads or 3 krads. The early floral initiation was not maintained in the M2progeny despite measurable quantities of radionuclides transferred through the M1seed to M2progeny, exposing the latter to low level chronic beta-ray exposure.The M2from90Sr- and137Cs-treated plants exhibited gross physiological changes (loss of apical dominance, dwarfism, gigantism, fasciation, etc.) and heritable mutations which persisted in the M3.

ISSN:0008-4026    

DOI:10.1139/b74-006

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

A survey of recent literature on the effects of low levels of air pollutants on plants, and the results of our experiments with low levels of ozone (< 0.1 ppm) on bean (Phaseolus vulgaris), barley (Hordeum vulgare), and smartweed (Polygonum lapathifolium) indicate stimulations of various growth parameters when compared with growth in clean, filtered air. Increasing knowledge of the composition of air in various regions of the world has been interpreted by some as evidence of increased air pollution. We argue that such a conclusion may not necessarily be valid, and that the observed levels of individual constituents may be indicative of long-term air composition. The similarity between the ambient levels of pollutants reported from numerous locations and those which result in stimulations of plant growth when compared with clean air, suggests that plants exhibiting such stimulations have adapted to low pollution levels, and hence are at a disadvantage when grown in clean air. We argue that the use of filtered air controls in experiments on the effects of air pollutants on plants is therefore unrealistic and misleading, and should be replaced by the use of ambient levels of pollution.

ISSN:0008-4026    

DOI:10.1139/b74-007

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

In vitro tests showed that mycelial growth ofPyrenochaeta terrestris(Hansen) Gorenz, Walker and Larson was inhibited by extracts from noninfected roots and bulbs of the pink-root-resistant onion cultivar Nebuka, and to a lesser extent by extracts from the moderately susceptible and highly susceptible Yellow Sweet Spanish and Southport White Globe, respectively. The active principle was shown to be fungistatic rather than fungicidal. Inhibitory activity of root and bulb extracts from Nebuka was eluted as a single peak from a Bio-Gel P-10 column. The inhibitory compound had anRfvalue of 0.44 on silica gel plates developed in a mixture of methyl ethyl ketone, pyridine, water, and glacial acetic acid (70:15:15:2). The compound reacted positively to ninhydrin, ammoniacal silver nitrate, bisdiazotized benzidine, and diazotized sulfanilic acid. The inhibitory effects of the compound were lost by heating or by exposure to extreme acid or base conditions. The inhibitory compound was without effect when column fractions were diluted 1:30 or more. Quantitative estimation of total phenols in extracts from onion cultivars ranging from highly resistant to completely susceptible showed that resistant cultivars contained about 35% more total phenols than did susceptible ones.

ISSN:0008-4026    

DOI:10.1139/b74-008

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Shifts in host metabolism during early stages of foliar infection and symptom development are examined.Verticillium dahliaeKleb. invaded and colonized chrysanthemum leaf tissue before symptom expression. Similar numbers of fungal propagules were recovered from non-symptomatic and symptomatic parts of a leaf lobe. No changes in relative water content, tissue permeability, RNA, and protein levels and only a slight decrease in chlorophyll level were detected within infected leaf tissue before the appearance of visible wilt. These data are discussed in relation to the possible role of senescence in theVerticilliumwilt syndrome in chrysanthemum.

ISSN:0008-4026    

DOI:10.1139/b74-009

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Principal component and Bray and Curtis ordination techniques were used to explore the ecology of lichen–moss ground-layer communities in Ontario and Wisconsin. The Ontario data included thirty-nine 100-m2stands from a large geographic region; lichen and moss relations along macroscale environmental and successional gradients were considered. Species relations along gradients of moisture and exposure were recognized. The Wisconsin data included one hundred sixty-six 0.5-m2quadrats from a single site in the Wisconsin Pine Barrens; species relations along microscale environmental gradients were examined. Gradients related to moisture, light, and temperature regimes were recognized. The ordinations provided a graphic display of the ground-layer lichen–moss community ecology and offered a basis for further work on the comparative autoecology of variousCladonialichens.Cladonia mitis, C. rangiferina, andC. uncialis, the subject of a subsequent paper in this series, were found to be similar in the macroscale but separated in the microscale ordinations.

ISSN:0008-4026    

DOI:10.1139/b74-010

出版商:NRC Research Press    

年代:1974

数据来源: NRC