摘要:

The development of the male gametophyte from western hemlock (Tsuga heterophylla(Raf.) Sarg.) pollen was complete after 5 days of incubation. This normally takes at least 6 weeks in vivo. The pollen was cultured in a solution containing boron, calcium nitrate, magnesium sulfate, and potassium nitrate. In 2 days the generative cell divided into the body cell and the stalk cell and after a further 3 days the body nucleus divided into two sperm nuclei. Morphological descriptions and measurements of the germinating pollen grains were made.

ISSN:0008-4026    

DOI:10.1139/b71-021

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Extracellular fluid was extracted by centrifugation from the tissue of the traps of the plant Venus's-flytrap. The extracted fluid was subjected to an extensive physicochemical analysis and the results were compared to a similar analysis of exudation sap. The results of the analysis of the extracted fluid served as a basis for the formulation of a physiological perfusion fluid which was compatible with the tissue of the flytrap. The methods used in the extraction and analysis of the fluid are described. The efficacy of the extraction method is discussed.

ISSN:0008-4026    

DOI:10.1139/b71-022

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Enhancement of elongation ofAvenaapical coleoptile segments byDL-fluorophenylalanines is specific for the para isomer. The ortho isomer is less than one-third as effective and the meta isomer has no effect. The in vitro activity of extractable phenylalanine ammonia lyase is inhibited equally well by para- and ortho-fluorophenylalanine and more strongly by the meta isomer. Inhibition was of the competitive type in all three cases. Chlorogenic acid levels were used to indicate the inhibition of phenylalanine ammonia lyase activity in vivo. Chlorogenic acid declined in controls. This decline was accelerated by the para isomer but not by the ortho isomer. The meta isomer protected against loss of chlorogenic acid. Enhancement of elongation was partially blocked bytrans-cinnamic acid, ferulic acid and coumarin but not by chlorogenic, caffeic, oro-coumaric acids. It is postulated thatp-fluorophenylalanine enhances elongation through depressed deamination of phenylalanine and consequent lowering of potentially inhibitory low molecular weight phenolic constituents.

ISSN:0008-4026    

DOI:10.1139/b71-023

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The vascular bundle of leaves with the C4-pathway of photosynthesis is usually surrounded by two concentric chlorophyllous cell layers: an outer mesophyll layer and an inner bundle sheath layer. The localization of the nitrate-assimilating enzymes, nitrate reductase, nitrite reductase, and glutamate dehydrogenase inZea mays, Gomphrena globosa, andSorghum sudanensewas studied by differential grinding. Nitrate reduction to nitrite appears to occur primarily in mesophyll cells. The nitrate content of the mesophyll cells was much higher than the nitrate content of the bundle sheath cells. The distribution of nitrite reductase seemed to be related to the presence of chloroplasts with grana. Ammonia incorporation into organic compounds by glutamate dehydrogenase was localized in the bundle sheath cells.

ISSN:0008-4026    

DOI:10.1139/b71-024

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

A study ofScirpuspopulations (sectionPterolepis)in the Saskatchewan River Delta was conducted to examine morphological and ecological characters of theScirpus acutusMuhl. andS. validusVahl complex to determine whether or not they should be differentiated as species.Population collections from stands ofScirpusand stands of suspected clonal hybrids were taken in 1966 and 1968 from various locations within the delta of the Saskatchewan River. Environmental data such as water depths were recorded at time of collection.Two morphologically and ecologically distinct groups emerged; their hybrids were sterile or nearly so. The features of panicle ray length and floral scale length: achene length ratio were found to be diagnostic morphological criteria for separating theScirpusexamined into two sets of distinct populations. These two sets of populations differed ecologically in terms of water depth tolerances: theS. acutustype tolerates between 60 and 150 cm, whereas theS. validustype occurs only at depths less than 65 cm.It was concluded that in the geographic area in which they were studied, these two separate populations would best be regarded as separate species.

ISSN:0008-4026    

DOI:10.1139/b71-025

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The development of fungi causing soft rots and of ensuing cavities in cell walls was studied with a new technique, consisting in inoculation of sterilized wood sections placed on agar slants. The senior author proposes a new system of classification of the soft rot fungi. Applied to investigations onCeratocystis ulmi(Buism.) C. Moreau, this technique permits further characterization of the morphology of this fungus, including the formation of microhyphae and microspore-like particles, often less than 0.5 μ in diameter, and recognition of the various configurations brought about by its growth in wood tissues. For example, microhyphae grow in a reticulate manner in close contact with starch grains, and these seem to break down.

ISSN:0008-4026    

DOI:10.1139/b71-026

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

Early stages of regeneration inFucus vesiculosusL. have been studied using segments of vegetative tissue from mature plants cultured in natural seawater. Changes in the production of sulfated polysaccharide at the wound surfaces of the segments were traced by light microscope autoradiography of applied35SO4−at various intervals after the plants were wounded. Within 6 h after wounding, newly synthesized sulfated polysaccharide is deposited at the extensively pitted cross walls which separate wounded and unwounded filament cells. As regeneration continues, this deposition is no longer confined to the cross walls but occurs throughout the extracellular matrix adjacent to the wound surface.Thin sections of regenerating segments were prepared for electron microscopy at intervals of up to 30 days of culture. Within 24 h after wounding, a layer of microfibrils probably composed of alginic acid is deposited asymmetrically within the existing cell walls of filament cells adjacent to wounded cells. About 2 weeks after wounding, the ends of filament cells adjacent to the wound surface expand laterally in the regions of cells where the newly deposited wall penetrates the original wall. Subsequent division and growth of these cells produces a ‘plate’ of cells at the wound surface which differentiates into new epidermis and cortex.

ISSN:0008-4026    

DOI:10.1139/b71-027

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The movement of14C from the old needles to the roots, and later to the new needles, was measured in 2-year-old ponderosa pine seedlings. The seedlings were in one of three growth stages at the time of the feeding of14CO2: 9 days before spring bud break with no root activity; 7 days before spring bud break with high root activity; and 7 days after spring bud break with moderate root activity. The form of the curves of count rate plotted against time are similar for a given plant part. Immediately after being fed14CO2, year-old needles had high14C count rates which dropped rapidly, leveled out within 7 to 10 days, and reached a steady state residual count rate after 10 to 20 days. The decrease in count rate from the old needles was followed by an increase in count rate by the root tip and (or) the new needles. The count rate of the root tips increased from background to a peak within 3 to 7 days, then decreased for the duration of the study. The details and timing of movement of14C to and from plant parts was a function of the growth state at the time of14CO2feeding.

ISSN:0008-4026    

DOI:10.1139/b71-028

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The daily variation of sorbitol, starch, sucrose, glucose, and fructose were estimated in the leaf of the apple,Malus pumilaMill., at 2-h intervals over 24-h periods in each of the months June to October, inclusive, 1968. Marked daily fluctuation in sorbitol concentration was observed in all months, accompanied by more moderate variations in the other carbohydrates. The patterns of concentration variability in sorbitol and starch were relatively similar compared to the more irregular patterns of the three sugars, sucrose, glucose, and fructose. In conjunction with its invariably very high leaf concentration relative to the other carbohydrates, the general daily pattern of sorbitol content, namely, a marked nocturnal decrease followed by a great increase during daylight, indicated that sorbitol is the major photosynthetically derived carbohydrate and is further evidence that sorbitol is a reserve carbohydrate in apple leaves.

ISSN:0008-4026    

DOI:10.1139/b71-029

出版商:NRC Research Press    

年代:1971

数据来源: NRC

摘要:

The bundle sheath chloroplasts ofSorghum bicolorlose their grana during ontogeny. Their ability to reduce the Hill reagent tetranitro blue tetrazolium chloride is also lost. Grana appear necessary for non-cyclic photosynthetic electron flow.

ISSN:0008-4026    

DOI:10.1139/b71-030

出版商:NRC Research Press    

年代:1971

数据来源: NRC