摘要:

The morphological changes ofChlamydomonas angulosainduced by treatment with an aqueous crude oil extract (ACOE) have been studied and compared with normal cells in the exponential phase of growth. Observations of oil-treated cells under the light microscope showed an effect on flagellar length and on motility, an increased activity of the contractile vacuoles, and an increase in granulations. Cells so treated become surrounded by a transparent envelope. By electron microscopy, the progression of ultrastructural changes has been followed. These changes include: a widened space between the cell wall and the plasmalemma; distorted and disorganized chloroplast lamellae; a decrease in density of the osmiophilic granules; and the presence of electron-dense deposits inside the cytoplasmic vacuoles. Cells were found to possess the ability to recover from the above abnormalities within an 8-day incubation period. Such a recovery corresponds to resumption of motility, capacity for growth, and photosynthesis, as described in other work. Based both on appearance, and on comparisons with bacterial, fungal studies, and cytochemical studies, it is suggested that the osmiophilic granules are lipid in nature and may act as a hydrocarbon sink. A self-cleansing mechanism is also suggested for these granules.

ISSN:0008-4026    

DOI:10.1139/b79-322

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The morphological changes ofChlamydomonas angulosa, when incubated with a 50% saturated solution of the aromatic hydrocarbon naphthalene, have been studied. Comparisons are made with the effects of crude oil. Observations under the light microscope reveal a totally inhibited motility, loss of flagella, an increase in the activity of the contractile vacuoles, and the appearance of cytoplasmic granulation. The cells were found to develop a surrounding transparent envelope. With electron microscopy, the following ultrastructural changes were revealed: the cell wall became partially thickened and a widened space developed between the cell wall and the plasmalemma; abnormal chloroplast lamellae developed, composed of numerous thylakoids; starch grains increased in number and in size; the osmiophilic granules of the stigma became a hollow core with peripheral structure and electron-dense material became heavily deposited inside the cytoplasmic vacuoles. This material stained deeply with Sudan black B, indicating its lipid nature. No recovery of cells was found during the 8-day incubation period with naphthalene, in contrast to recoveries noted with crude oil treatment. The lipid deposits in the vacuole also showed no indication of migration or reduction during this period.

ISSN:0008-4026    

DOI:10.1139/b79-323

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Phenology and states of dormancy ofUtricularia vulgariswere studied using plants and turions collected at intervals throughout the growing season of 1977 from a shallow eutrophic pond in central Alberta located at 53°25′ N, 113°46′ W. States of dormancy and the effects of photoperiod and temperature were determined by the potential for sprouting and subsequent apical growth under long-day (18 h, 20 °C), short-day (12 h, 20 °C), and high-temperature (16 h, 30 °C) conditions, with and without varying periods of chilling at 2–3 °C. Physiological changes associated with different states of dormancy such as frost hardiness, starch content, and dark respiration were also investigated. Turions were formed 1 month after summer solstice and entered a state of innate dormancy during which only a high-temperature treatment at 30 °C would induce sprouting. Plants from innately dormant turions that were forced to sprout and were then cultured at 20 °C invariably reentered dormancy by the production of new turions. Turions collected in the late stages of innate dormancy could withstand −8 °C but not −12 °C. As temperatures dropped and ice cover became continuous, turions entered an imposed state of dormancy during which immediate sprouting and continued vegetative growth occurred under all conditions. Starch content reached a maximum of 49 mg g−1fresh weight during early innate dormancy and declined steadily thereafter. Dark respiration in response to temperature of plants obtained from turions collected during innate and imposed dormancy states differed above 25 °C but was similar below.

ISSN:0008-4026    

DOI:10.1139/b79-324

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The roles of endogenous and exogenous growth regulators on dormancy control ofUtricularia vulgariswere investigated by extraction and bioassay of endogenous levels of four classes at various developmental stages and by measuring the effects of synthetic regulators on these stages. The bioassays used were oat coleoptile for auxins, abscisic acid and other inhibitors; lettuce hypocotyl for gibberellins; and soybean callus for cytokinins. Two weeks before turion formation and during innate dormancy abscisic acidlike and bound gibberellinlike levels were high while free gibberellinlike and auxinlike levels were low. Abscisic acid exogenously applied to actively growing plants rapidly induced turion formation even under noninductive environmental conditions. Kinetin rapidly and completely caused sprouting in innately dormant turions but would not promote continued vegetative growth. These plants formed new turions within 2 weeks of sprouting. During imposed dormancy, when turions rapidly sprouted, there was a low level of abscisic acidlike inhibitor and high levels of gibberellinlike and auxinlike compounds. Turions collected during this state could be maintained in a dormant condition by incubation with abscisic acid even at high temperatures which normally induce sprouting. During sprouting the endogenous growth regulator pattern was similar to that described for imposed dormancy. A model of the environmental and growth regulator factors which control dormancy is presented.

ISSN:0008-4026    

DOI:10.1139/b79-325

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Two samples of plants ofCelosia cristata, a quantitative short-day plant, were grown in an 8-h or a 16-h day. The shoot apices were collected at 11, 15, 18, and 28 days in order to carry out a cytophotometric study of the nuclear DNA in thecorpus. This distribution of the DNA values was analyzed statistically using the χ2test. At the beginning of development, for both 8-h day and 16-h day plants, the DNA content of the majority of the nuclei is at the 2C level. Then the percentage 2C–4C or 4C nuclei increases, slowly for the plants grown under a 16-h photoperiod and quickly for the others. At the 28th day, the Gaussian distribution of DNA values indicates that the state reached by the meristems is quite different. Between the 18th day and the 28th day of culture, ontogenesis of the shoot apex goes through a critical period. At the end of this period, shoot apices of the plants grown under a 16-h photoperiod are in the intermediate phase with a majority of nuclei in the synthetic phase (S) or in the postsynthetic phase (G2). Simultaneously, structural modifications of the axial zone give rise to a central zone characteristic of the fasciation of the shoot apex. In plants grown with an 8-h photoperiod, the shoot apex goes through the prefloral phase with more numerous nuclei in the presynthetic phase (G1) or in the synthetic one (S). For each sample the nuclei clustered in a particular phase of the cell cycle indicate that a certain synchronism of the cell cycles in thecorpustakes place. These results are compared with those recently obtained by other authors working with different plants.

ISSN:0008-4026    

DOI:10.1139/b79-326

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

A variety of the mosquito pathogen,Coelomomyces psorophorae, collected at Fincastle, Alberta, has been maintained in laboratory-reared larvae ofCuliseta inornataand in cultures of the copepod,Cyclops vernalis. Despite earlier speculation, the fungus appears to have a relatively broad host range as revealed by preliminary host-specificity studies. Seven of the 12 mosquito species tested became infected. One species,Aedes vexans, known to be a host forC. psorophoraewas not infected, confirming experimentally that host-specific varieties of this species of fungus do exist. Staining with a dilute solution of methylene blue revealed that the fungus encysts in definite patterns on the cuticles of both host animals. Penetration occurs through the cuticle and not through the digestive tract. A correlation between attachment and susceptibility was obvious in these limited trials.

ISSN:0008-4026    

DOI:10.1139/b79-327

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The modification of the genotype of the Cadet and Rescue cultivars of spring wheat (Triticum aestivumL. emend. Thell) by disomic chromosome substitution altered the amount of plant nitrogen derived from dinitrogen fixation by the associated bacterium in a phytotron experiment. With the exception of the C-R5B line, inoculation of the parent Cadet or its substitution lines with either the bacillus C-11-25 orAzospirillum brasilenseincreased plant dry matter and the total N yield. Rescue lines were unaffected by inoculation unless genotypically altered by substitution of the 5B or 5D chromosome from Cadet. Different substitution lines reacted uniquely to inoculation with the specific bacteria: C-R2A and R-C2D promoted greater dinitrogen fixation byA. brasilense; C-R5D, R-C5B, and R-C5D promoted greater dinitrogen fixation by the C-11-25 bacillus. Both bacteria had high and identical levels of dinitrogen fixation in association with the C-R2D line; neither bacterium fixed N when grown in association with the C-R5B, Rescue, or R-C2A lines. Although the ability of spring wheat to induce dinitrogen fixation in associated bacteria is influenced by chromosomes 5B (which controls root rot reaction) and 5D, it does not appear to be directly related to reaction to common root rot.

ISSN:0008-4026    

DOI:10.1139/b79-328

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Mature roots from banana and representatives of eight other families of the Monocotyledonae examined by electron microscopy showed isotropic layers (IL) in the secondary cell walls of mature fibers. These IL were shown by histochemical tests to be rich in pectin and lignin and to correspond to the primary wall in composition. The IL occurred between layers of cellulosic secondary walls that exhibited differentiation into the typical S1and S2layers. The resultant structure gave the appearance of a succession of complete cell walls laid down inside one another. This structure appears to be of common occurrence in the mature fibers of woody monocotyledons.

ISSN:0008-4026    

DOI:10.1139/b79-329

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Pollen development in a male-fertile and a cytoplasmic male-sterile line of rye (Secale cerealsL.) was investigated using histological techniques. In the male-fertile line a high degree of organization was evident within the locule, and polarity within the microspore was also apparent. In the male-sterile line, development appeared to proceed normally until the tetrad stage. Just after tetrad breakup, the tapetum became vacuolate and invaded the locule. Two days later the organization within the locule had broken down completely. Microspores and tapetum had become an unorganized mass within the locule. By 10 days after tetrads, the middle layer had also broken down. At dehiscence the contents of the locule remained as a compressed layer over the endothecium of the anther.

ISSN:0008-4026    

DOI:10.1139/b79-330

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Water and phytoplankton samplings were taken in three little Laurentide lakes from July 4, 1972, to October 29, 1973. Of the 111 species identified, 66 are found in Lake Triton (maximum depth 3 m, pH 6.8, conductivity 30 μmhos/cm; 1 mho = 1 S), 62 in Lake Geai (6 m, pH 5.8, 22 μmhos/cm) and 47 in Lake Croche (8 m, pH 6.5, 25 μmhos/cm). The greatest number of species belong to Diatoms and Desmidiaceae. However, the most numerous algae are Chrysophyceae, at least in some months of the year in the three lakes, and Cyanophyceae in Lake Geai.

ISSN:0008-4026    

DOI:10.1139/b79-331

出版商:NRC Research Press    

年代:1979

数据来源: NRC