摘要:

The metabolic activities of living sapwood ray cells ofPicea mariana(Mill.) BSP. were studied and the nuclear slenderness ratio was compared with a new indicator, the nuclear elongation index. For comparative studies of the two indicators, 40 living sapwood ray cells from earlywood uniseriate rays of 11 sapwood growth rings were measured for cell length, nuclear length, and nuclear width. For the study of the relationship between the ray cell length and nuclear length, 40 earlywood and 34 latewood cells of the first, second, and fifth growth rings of sapwood of specimens collected in May were measured. A strong positive relationship between the nuclear length and the ray cell length existed in the three studied growth rings. A general decreasing trend of cell activity in the living sapwood ray cell was shown by both indicators. However, the new indicator, the nuclear elongation index, shows a smoother curve than that exhibited by the old indicator.

ISSN:0008-4026    

DOI:10.1139/b87-245

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

A previously undescribed member of the genusMallomonas(Chrysophyceae) has been found in several Ontario soft-water lakes. Its scale and bristle structure is reminiscent ofM.acaroides; however, it has been assigned new variety status (Mallomonas acaroidesvar.muskokana). There are several features of scale and bristle structure that serve to separate this taxon from its closest relatives,M.acaroidesvar.acaroidesPetty emend. Iwanoff andM.acaroidesvar.inermisFott.

ISSN:0008-4026    

DOI:10.1139/b87-246

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Detergent-soluble polypeptides from urediosporelings and purified germ-tube walls of urediosporelings of wheat stem rust,Puccinia graminisf.sp.tritici, races C1(17), C17(56), and C36(48) were separated by two-dimensional isoelectric focusing – polyacrylamide gel electrophoresis. More than 280 polypeptides were distinguished by Coomassie brilliant blue staining in each race, and there were 18 polypeptides that varied among the three races, 7 of which were coincident with urediosporeling wall polypeptides. Polypeptides transferred from two-dimensional gels onto nitrocellulose membrane were either stained with India ink or probed with concanavalin A – peroxidase for the location of concanavalin A binding glycoproteins. Of 97 concanavalin A binding glycoproteins in urediosporelings, 41 were coincident with polypeptides that stained with Indian ink and 3 were coincident with race-variable polypeptides. The walls of urediosporelings contained few polypeptides that stained with Coomassie brilliant blue or India ink, but most were concanavalin A binding. None of the polypeptides had affinity to soybean agglutinin orLotuslectin, suggesting that galactose or fucose is not a terminal sugar moiety in these polypeptides. We conclude that race-variable polypeptides are located both within the cytoplasm and in the walls of urediosporelings, but most are not glycosylated.

ISSN:0008-4026    

DOI:10.1139/b87-247

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Three new Holocene pollen percentage and accumulation rate diagrams for southern Ontario are presented. They greatly increase the available information on the history of the area's forest trees and permit a discussion of the competitive interactions that have brought about the forest pattern seen today. In the earliest Holocene, the forests were dominated byPicea, which was replaced by firstPinus banksiana–resinosaand thenPinus strobus. In extreme southern Ontario,Pinus strobuswas replaced byAcer saccharumandFagus grandifolia, but in the area east of Georgian Bay,Tsuga canadensisbecame the dominant, and near Mattawa,Betula(probablylutea). Late Holocene stability of forests is considered to be a function of the lack of taxa better able to compete than those already present.

ISSN:0008-4026    

DOI:10.1139/b87-248

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

The presence of aScopulariopsisBainier anamorph inPithoascus schumacheri(Hansen) von Arx is reported.Pithoascus langeroniivon Arx is transfered to the monotypic new genusPithoascina, on the basis of ascospore morphology and conidial state. The new combinationPithoascus stysanophorus(Matt.) Valmaseda, Martínez & Barrasa is also proposed. The relationship between the generaPithoascusvon Arx andMicroascusZukal is discussed.

ISSN:0008-4026    

DOI:10.1139/b87-249

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Flavoparmelia caperata(L.) Hale andUmbilicaria mammulata(Ach.) Tuck, were exposed to 262 μg SO2 m−3, 59 μg O3 m−3, and 262 μg SO2 m−3in combination with 59 μg O3 m−3for 20 h over a 5-day period. Photosynthesis and ultrastructural observations were made after 12 and 20 h. At these low concentrations of pollutants, ultrastructural changes preceded and accompanied decreases in photosynthesis rates. Ozone was more phytotoxic than SO2. Ultrastructural damage was least with SO2and greater and very similar with O3and the combination of O3and SO2. Photosynthetic data showed that SO2ameliorates effects of O3. Electron micrographs showed increased accumulation of starch and cavity space around starch grains in the chloroplast and increased lipids in the cytoplasm inF.caperata; there was some increased starch inU.mammulata, but alterations were primarily in increased chloroplast opacity. Photosynthesis ofU.mammulatawas more sensitive to the pollutants than that ofF.caperata. Ultrastructural damage was greater when samples were stored in the light than when they were stored in the dark between fumigations. The study shows that species vary in their responses to pollutants and that combinations of pollutants may give results different from those obtained with single pollutants.

ISSN:0008-4026    

DOI:10.1139/b87-250

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

A population of the grassDanthonia spicatagrowing in a pine–hardwood forest in northern lower Michigan was studied before, during, and after a period of major disturbance. Samples of the aboveground population were collected after clear-cutting but before fire, 9 days after fire, 10 months after fire, and 13 months after fire. Change was examined by growing clonally replicated genets in a series of light and watering treatments in the greenhouse. There was a significant change in the composition of the population after fire. Genets collected following the fire grew faster and larger in the 100% light treatment than individuals collected before the fire. Differences among collections were small or not significant for plants grown in the 20 and 6% light treatments. The watering treatments showed little or no effects. Although there are limitations in the interpretation of common garden studies, the differences among collections appear to have a genetic basis. The growth characteristics of genets collected after the fire showed possible adaptation to postfire conditions. These results suggest a greater importance for genetic adaptation in the persistence ofD.spicataduring secondary succession than had been concluded from earlier experiments.

ISSN:0008-4026    

DOI:10.1139/b87-251

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Eleven alkaline western Canadian montane streams were sampled by transects to compare the bryophyte species cover, diversity, frequency, richness, niche width, and niche overlap in three vertical zones (relative to water level) with the same parameters in four acidic streams on Slide Mountain in the Adirondack Mountains of New York. Resources for niche width and overlap include vertical distance from water surface, aspect in stream, substrate size, and percent bare substrate. Species cover, richness, and diversity increase from the submerged zone 1 (< −5 cm) to the terrestrial zone 3 (10–30 cm). Brillouin species diversity increases from 1.98 to 3.03 (means per stream) along the same gradient. All species except one from zone 1 also occur in zone 3. The niche widths for aspect in stream, substrate size, and vertical distance from water surface are all negatively correlated with their chi-square values, indicating that the width values are most reliable for small widths and become increasingly less reliable for large niche widths. Niche overlap is high among most species for at least one resource parameter.

ISSN:0008-4026    

DOI:10.1139/b87-252

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Fleshy (noncalcified) crustose algae are abundant throughout the intertidal zone in Washington State. Crusts include members of the Chlorophyta, Phaeophyta, Rhodophyta, Cyanobacteria, and marine lichens and represent a variety of life-history patterns. Some of the 14 taxa studied are observed only in specific habitats (e.g., only in the low or high intertidal zone or in pools), whereas others are broadly distributed throughout the intertidal zone. All crusts are patchy in their distribution, and their thicknesses show no trends with tidal height. The reproductive periodicity of 10 common fleshy species was studied over 2 years. Most crusts reproduce in the fall and winter, but none is rigidly tied to a seasonal pattern. A key to the fleshy crusts is provided.

ISSN:0008-4026    

DOI:10.1139/b87-253

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Based on autoradiographic (210Pb) and ultrastructural studies, it was determined that lead is taken up from solution with the same intensity along the length ofAllium cepaL. roots. As expected, the rate of uptake is dependent on the lead concentration and exposure time of the roots to lead salts. Lead takes about 80 min to penetrate radially through consecutive root tip layers in the meristematic zone. Lead is first deposited on the root surface, and then is translocated radially through the middle lamella (apoplast) of root cap cells. The lead reaches protoderm cells and meristematic cells of the hypodermis, where it penetrates into the symplast. Lead passes through consecutive ground meristem tissue layers at the rate of 1 cell layer/5 min. Its deposition in the ground meristem tissue is surprisingly nonuniform. It is deposited uniformly in the first six layers, but in the deeper (7th to 10th) layers, lead deposits are encountered in intercellular spaces and the middle lamellae, then in the cell walls near the plasmalemma, and finally in vacuoles.

ISSN:0008-4026    

DOI:10.1139/b87-254

出版商:NRC Research Press    

年代:1987

数据来源: NRC