摘要:

Pachyella, characterized by amyloid asci, globose cells in the ectal excipulum, hyphoid hairs, and gelatinous tissue, is treated monographically. A total of six species are discussed. The new combinationsP. adnata, P. violaceonigra, andP. megalospermaare proposed and one new species,P. punctispora, is described.

ISSN:0008-4026    

DOI:10.1139/b73-262

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Electron microscopy of the cells of the characean algaNitella flexilisrevealed the presence of numerous spherical inclusions which morphologically resemble plant microbodies. The structures have a dense granular matrix and are bounded by a single membrane. Many of the microbodies contain very electron-dense nucleoids that were shown to be alpha-amylase sensitive. In cells of the young apex, microbodies are the most abundant cellular organelle and are intimately associated with dilated cisternae of the endoplasmic reticulum and Golgi complexes, and with large osmiophilic lipid bodies. Although the microbody population appears reduced in mature branchlet cells and internode cells of the main axis, they exhibit a characteristic and frequent association with the chloroplasts. Turnover of microbodies involves some autolytic degradation of the body matrix until complete digestion presumably occurs. Developmental changes of microbodies were monitored with the cytochemical localization of lysosomal aryl sulfatase and acid phosphatase activities. The current study is of interest since catalase, an enzyme marker of microbodies in a variety of tissues, could not be detected using both cytochemical and enzyme assay methods. The functional role of microbodies inNitellacells is explored in relation to presently available information.

ISSN:0008-4026    

DOI:10.1139/b73-263

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Electron microscopy of conidiogenesis inTritirachium roseumwas done on material fixed in glutaraldehyde followed by OsO4. The walls of conidiogenous cells, though pigmented, lacked well-defined differential electron-transmission layers. Conidial initials developed without the appearance of a rupture in the conidiogenous cell wall, i.e., development was holoblastic. Each successively produced conidiogenous locus developed below and to one side of the previously formed conidium, and the fertile region of the conidiogenous cell elongated in a geniculate pattern. After each conidial initial reached full size, it was delimited by a centripetally developing septum, which increased in thickness, became double, and split during conidial secession. The distal half of a split septum formed the conidial base; the proximal half remained as part of the conidiogenous cell wall. Upon conidial secession, basal frills on conidia, and secession scars on conidiogenous cells were especially conspicuous.

ISSN:0008-4026    

DOI:10.1139/b73-264

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Floral and mineral composition of the vegetation on 12 foothill grassland sites in the Eastern Great Basin has been studied. Aboveground production differed widely among the sites (871–2388 kg/ha per year). Both floristic and mineral composition of the vegetation changed conspicuously across the productivity gradient. As production increased, total nutrient uptake by the aboveground vegetation also increased. This increase was only partially due to greater production; average nutrient content per gram of tissue (all species pooled) also increased along the productivity gradient.Roughly 82% of the variation in total annual production was accounted for using an index of site mesicness. Mesic sites were dominated by forbs, while grasses or shrubs were dominant on xeric sites. The mesic sites were far more productive than xeric sites. The greater nutrient element content of plant tissue from the most productive sites in this study was related more to a shift in dominance from grasses and shrubs to forbs, than to nutrient status of the soil.

ISSN:0008-4026    

DOI:10.1139/b73-265

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Eight constitutive isoperoxidases were separated by the disc method of polyacrylamide gel electrophoresis from a lyophilized extract of 8-day-old oat (Avena sativaL., cv. Victory) coleoptiles. Both anodic and cathodic isoperoxidases were studied and differences in electrophoretic mobilities and hydrogen donor substrate specificities were revealed. In addition, by enzyme assay, cathodic and anodic isoenzymes were shown to possess differences in peroxidase and IAA (indole-3-acetic acid) oxidase activities.Treatment of coleoptiles with 0.07 mM IAA for 24 h resulted in the repression of two slow-migrating anodic isoperoxidases; however, the same treatment also resulted in the induction of two slow-migrating cathodic isoenzymes which were shown to exhibit peroxidase and IAA oxidase activities.

ISSN:0008-4026    

DOI:10.1139/b73-266

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Numerical techniques were used to investigate published data from studies on the genusRhizopus. These techniques have produced a classification broadly in agreement with that based on a more classical approach, but a regrouping of the Oryzae section of the genus, which has been the most difficult to classify in the past, is proposed. This work was based on a study of 149 attributes of each of 34 individuals. An investigation of the characters revealed that with the possible exception of temperature-response characters no particular sets of characters can be said to contribute significantly to the classification. An investigation of seven of the previous classifications using objective methods shows that three classifications are in general agreement with the one tentatively proposed here.

ISSN:0008-4026    

DOI:10.1139/b73-267

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Mitosis in zoosporangia of the chytridPhlyctochytrium irregulareis described from electron microscope observations and also from light microscope observations of both living and haematoxylin-stained thalli. At the onset of prophase the centriole complex replicates, and the complexes migrate to polar positions. The semi-persistent nucleolus is appressed to the nuclear envelope as the nuclear pockets invaginate, finally rupturing to create polar fenestrae, through which spindle microtubules penetrate the nucleus from the region of the centrioles at prometaphase. Metaphase chromosomes form an equatorial plate. Initial separation at anaphase seems to be accomplished mainly by shortening of chromosome-to-pole microtubules; additional anaphase and telophase separation is accomplished by elongation of the nucleus. A system of perinuclear endoplasmic reticulum is formed during prophase and is completed by metaphase. It persists during all division stages after its formation. Features of this mitotic apparatus are discussed with reference to earlier light microscope studies of chytrid mitosis. The ultrastructure ofP. irregulare'smitotic apparatus is similar to that of certain unicellular green algae.

ISSN:0008-4026    

DOI:10.1139/b73-268

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Although eastern North American populations ofSanguisorba canadensisL. are reported to be octoploid and plants of western North America reported to be tetraploid, it was found that this species is usually tetraploid,2n = 28, throughout its range. No octoploids were found among the plants studied, even in material from the locations where octoploids have been reported to occur.

ISSN:0008-4026    

DOI:10.1139/b73-269

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Movement of N6-benzyladenine-methylene-14C inAvena sativacoleoptiles,Colens blumeistems and petioles, andCleome hasslerianastamen filaments, gynophores, and pedicels was studied by suspending sections horizontally between donor and receiver agar cylinders and determining radioactivity in receivers by scintillation counting. No polar movement was found in any of the plant organs. In time-course experiments using oat coleoptiles, the amount of radioactivity in receivers continued to increase for 24 h and the velocity was 1.5-2 mm/h, suggesting movement by passive diffusion. More radioactivity moved through stamen filaments and gynophore sections from mature expanded flowers than through those from young buds, apparently as a result of larger uptake and exit areas in expanded flowers. A significantly greater acropetal and basipetal movement through young pedicels is not due to area differences and probably results from a metabolic difference.

ISSN:0008-4026    

DOI:10.1139/b73-270

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

The postglacial vegetation history of the University of British Columbia Research Forest was investigated using percentage and absolute pollen analysis, macrofossil analysis, and radiocarbon dating. A marine silty clay deposit records the oldest (12 690 ± 190 years before present (B.P.)) assemblage of terrestrial plant remains so far recovered from the postglacial of south-coastal British Columbia. Lodge-pole pine (Pinus contorta) dominated this early vegetation, although someAbies, Picea, Alnus, and herbs were also present. Sediment cores from two lakes were also studied. The older is Marion Lake, where five pollen assemblage zones are recognized, beginning with a previously undescribed assemblage ofPinus contorta, Salix, andShepherdiain clay older than 12 350 ± 190 B.P. The pollen diagram from Surprise Lake (11 230 ± 230 B.P.) is divided into three pollen zones which show the same major trends of vegetation change as the Marion Lake diagram.The first report of the postglacial vegetation history of cedar (Thujaand perhapsChamaecyparis) in southwestern British Columbia is presented from pollen and macrofossil analyses.At about 10 500 B.P. in both lakes, pollen of Douglas fir (Pseudotsuga menziesii) began a rapid increase, probably in response to climatic amelioration. The palynological evidence, supported by well-preserved bryophyte subfossils, suggests that humid coastal conditions have prevailed in the study area since about 10 500 B.P., with virtually no evidence for a classical Hypsithermal interval between 8500 B.P. and 3000 B.P.

ISSN:0008-4026    

DOI:10.1139/b73-271

出版商:NRC Research Press    

年代:1973

数据来源: NRC