Showing papers by "University of Guelph published in 1983"

Hybridization process utilizing a combination of cytoplasmic male sterility and herbicide tolerance

Abstract: The process of the present invention provides a convenient route for producing a predetermined hybrid variety of a crop which is capable of undergoing both self-pollination and cross-pollination. Cytoplasmic male sterile plants which also exhibit cytoplasmic herbicide tolerance are the key plants for use in the present process. Such cytoplasmic male sterile plants may be readily multiplied and uniformly produced in accordance with the process of the present invention on a relatively economical basis by crossing with suitable maintainer plants. Economical bulk planting of the key plants with either maintainer or restorer plants is made possible. Following cross-pollination from a pollen source which lacks the herbicide tolerance unneeded plants effectively are eliminated by use of a herbicide. For instance, unwanted plants may be effectively eliminated immediately after pollination or prior to pollination in a succeeding generation to make possible the existence in an unharmed state of a substantially homogeneous stand of the desired plants which exhibit cytoplasmic herbicide tolerance. The process of the present invention is applicable to grain crops, forage crops, seed propagated fruits, seed propagated ornamentals, and industrial species. In a particularly preferred embodiment a predetermined variety of Brassica napus (i.e., rape or improved forms thereof known as canola) is formed which is the product of cross-pollination.

Small-scale structure of the Taylor–Green vortex

Abstract: The dynamics of both the inviscid and viscous Taylor–Green (TG) three-dimensional vortex flows are investigated. This flow is perhaps the simplest system in which one can study the generation of small scales by three-dimensional vortex stretching and the resulting turbulence. The problem is studied by both direct spectral numerical solution of the Navier–Stokes equations (with up to 256 3 modes) and by power-series analysis in time. The inviscid dynamics are strongly influenced by symmetries which confine the flow to an impermeable box with stress-free boundaries. There is an early stage during which the flow is strongly anisotropic with well-organized (laminar) small-scale excitation in the form of vortex sheets located near the walls of this box. The flow is smooth but has complex-space singularities within a distance $\hat{\delta}(t)$ of real (physical) space which give rise to an exponential tail in the energy spectrum. It is found that $\hat{\delta}(t)$ decreases exponentially in time to the limit of our resolution. Indirect evidence is presented that more violent vortex stretching takes place at later times, possibly leading to a real singularity ( $\hat{\delta}(t) = 0$ ) at a finite time. These direct integration results are consistent with new temporal power-series results that extend the Morf, Orszag & Frisch (1980) analysis from order t 44 to order t 80 . Still, convincing evidence for or against the existence of a real singularity will require even more sophisticated analysis. The viscous dynamics (decay) have been studied for Reynolds numbers R (based on an integral scale) up to 3000 and beyond the time t max at which the maximum energy dissipation is achieved. Early-time, high- R dynamics are essentially inviscid and laminar. The inviscidly formed vortex sheets are observed to roll up and are then subject to instabilities accompanied by reconnection processes which make the flow increasingly chaotic (turbulent) with extended high-vorticity patches appearing away from the impermeable walls. Near t max the small scales of the flow are nearly isotropic provided that R [gsim ] 1000. Various features characteristic of fully developed turbulence are observed near t max when R = 3000 and R λ = 110: a k − n inertial range in the energy spectrum is obtained with n ≈ 1.6–2.2 (in contrast with a much steeper spectrum at earlier times); th energy dissipation has considerable spatial intermittency; its spectrum has a k −1+μ inertial range with the codimension μ ≈ 0.3−0.7. Skewness and flatness results are also presented.

Shoreline Vegetation in Axe Lake, Ontario: Effects of Exposure on Zonation Patterns

Abstract: This study tests several hypotheses relating community structure to environmental disturbance, by testing for changes in the zonation patterns of lakeshore vegetation. Twenty—five transects were examined at different positions along an exposure gradient. The range of water depths tolerated by individual species (realized niche width) changes with exposure. Some (Lobelia dortmanna, Utricularia cornuta) reached their maximum on exposed shores, others (Drosera intermedia, Cladium mariscoides) at intermediate exposure, and others (Pontederia cordata, Triadenum fraseri) on sheltered shores. Species richness peaked significantly at intermediate levels of exposure (P < .01). In spite of changes in both species composition and richness, mean niche width did not change with exposure. The distribution of the upper and lower limits of species along the gradient was examined using measures of boundary clustering. The lower and upper boundaries of species were both significantly clustered (P < .001), suggesting discrete communities exist on the shoreline gradient. As exposure increased, upper boundaries became more cluster (P < .002); lower boundaries were unaffected. The distribution of boundaries shifted landward with increasing exposure. This fact is possibly related to an identical landward shift in the lower boundaries of shoreline shrubs, which appear to have a major influence on the distribution of herbaceous shoreline vegetation.

Structure of the Reynolds Stress in a Canopy Layer

Abstract: The u, w velocity covariance above and within a plant canopy (Zea mays L) was examined using the technique of quadrant analysis to separate the momentum transport into events classified as sweep, ejection, and outward and inward interactions. A hyperbolic hole of variable size acted as an excluded region in the u, w domain to asses the relative importance of short-lived events of large magnitude. The results of the analysis were a reasonably close match to rough-wall wind tunnel studies but differed in some respects from a similar experiment performed elsewhere in a flexible wheat canopy. Generally, sweeps exceeded ejections in their contribution to the Reynolds stress, especially at mid-canopy, while the interaction events were of minor importance. Sweeps that were large in magnitude relative to the time-averaged stress were evident at all levels and were intermittent in character. Compared with the layers above, the effect of the canopy was to increase the dominance of sweeps over ejections and...

Magic‐Angle‐Spinning NMR (MAS‐NMR) Spectroscopy and the Structure of Zeolites

Abstract: After outlining the chemical features and properties which make zeolites such an important group of catalysts and sorbents, the article explains how high-resolution solid-state NMR with magic-angle spinning reveals numerous new insights into their structure. 29Si-MAS-NMR readily and quantitatively identifies five distinct Si(OAl)n(OSi)4-n structural groups in zeolitic frameworks (n = 0, 1,….4), corresponding to the first tetrahedral coordination shell of a silicon atom. Many catalytic and other chemical properties of zeolites are governed by the short-range Si, Al order, the nature of which is greatly clarified by 29Si-MAS-NMR. It is shown that, as expected from Pauling's electroneutrality principle and Loewenstein's rule, both in zeolite X and in zeolite A (with Si/Al = 1.00) there are no AlOAl linkages. In zeolite A and zeolite X with Si/Al = 1.00 there is strict alternation of Si and Al on the tetrahedral sites. Ordering models for Si/Al ratios up to 5.00 (in zeolite Y) may also be evaluated by a combination of MAS-NMR experiments and computational procedures. 29Si-MAS-NMR spectra reveal the presence of numerous crystallographically distinct Si(OSi)4 sites in silicalite/ZSM-5, suggesting that the correct space group for these related porosilicates is not Pnma. 27Al-MAS-NMR clearly distinguishes tetrahedrally and octahedrally coordinated aluminum, proving that, contrary to earlier claims, Al in silicalite is tetrahedrally substituted within the framework. In combination, 29Si- and 27Al-MAS-NMR is a powerful tool for monitoring the course of solid-state processes (such as ultrastabilization of synthetic faujasites) and of gas-solid reactions (dealumination of zeolites with silicon tetrachloride vapor at elevated temperatures). They also permit the quantitative determination of framework Si/Al ratios in the region 1.00 < Si/Al < 10 000. Since most elements in the periodic table may be accommodated within zeolite structures, either as part of the exchangeable cations or as building units of the anionic framework, there is immense scope for investigation by MAS-NMR and its variants (cross-polarization, multiple pulse and variable-angle spinning) of bulk, surface and chemical properties. Some of the directions in which future research in zeolite science may proceed are adumbrated.

Conversion of used frying oil to diesel fuel by transesterification: preliminary tests

Abstract: Used frying oil was transesterified by reaction with excess alcohol under both acidic and basic conditions. The alcohols used were: methanol, ethanol, 1-propanol, 2-propanol, 1-butanol and 2-ethoxyethanol. Yields of the fuels determined by gas chromatography and their viscosities are reported. The best result was obtained using methanol with catalysis by potassium hydroxide. The methyl ethyl and 1-butyl esters all ran very well in short-term engine tests with a laboratory high-speed diesel engine.

Redd-site selection by brook trout and brown trout in southwestern Ontario streams

Abstract: Redd-substrate composition, water velocity, depth, and other environmental variables associated with redd-site selection and spawning by brook trout Salvelinus fontinalis and brown trout Salmo trutta in southwestern Ontario streams were examined. Sympatric and allopatric populations spawned in similar ranges of specific conductance (225–810 μmhos/cm), pH (7.0–8.2), dissolved oxygen (>83% saturation), and stream gradient (0.2–2.3%). Brook trout spawned exclusively in areas of groundwater seepage, typically near headwaters where streamflow did not exceed 177 litres/second. Brown trout spawned in a wider range of flows (21–600 liters/second), and utilized locations with and without groundwater seepage. Spawning by brook trout usually began by the second week of October, by brown trout a week later. Brook trout spawning periods lasted 3–5 weeks, those of brown trout, 2–4 weeks. In sympatric populations, an overlap in spawning time occurred for up to 3 weeks. Reuse of redds was mostly intraspecific, a...

Characterization of the gene encoding heat-stable toxin II and preliminary molecular epidemiological studies of enterotoxigenic Escherichia coli heat-stable toxin II producers

Abstract: The gene encoding heat-stable toxin II (STII) was cloned into an Escherichia coli K-12 strain, and its nucleotide sequence was determined. The deduced amino acid sequence indicates that STII is synthesized within the cell as a 71-amino-acid protein and that neither the DNA nor amino acid sequence bears any similarity to that of heat-stable toxin I. A DNA fragment containing the STII gene was used to probe enterotoxigenic E. coli clinical isolates with various toxin phenotypes and was shown to be useful in detecting all STII and only STII producers.

Restriction patterns reveal origins of chloroplast genomes in Brassica amphiploids.

Abstract: Chloroplast (ct) DNA from the three elementary Brassica species (B. nigra (L.) Koch, B. oleracea L. and B. campestris L.) and the three amphiploid Brassica species (B. carinata A. Br., B. napus L. and B. juncea (L.) Czern.) was digested with fifteen restriction endonucleases. In all species restriction sites for enzymes with GC-rich recognition sequences were less frequent and not as variable as for those with AT-rich sequences. Comparisons between species revealed two distinct groups of ct DNA fragment patterns: complex one, composed of B. oleracea, B. napus, B. campestris and B. juncea and complex two, composed of B. nigra and B. carinata. The patterns of B. carinata were virtually identical to those of B. nigra and those of B. juncea were virtually identical to those of B. campestris indicating not only where the ct genomes of B. carinata and B. juncea originated, but also how little these genomes have been altered since the origin of these amphiploids. Ct DNA in B. napus shows more homology with that of B. oleracea than with that of B. campestris, but the ct genome of this amphiploid has diverged more from that of its putative parent than have those of the other two amphiploids.

Vomitoxin in corn fed to young pigs.

Abstract: Summary Four trials were conducted with young pigs to evaluate the effect of dietary level of vomitoxin-contaminated corn on performance and pathology. A dietary level of approximately 20 ppm vomitoxin caused vomiting, 12 ppm vomitoxin caused almost complete feed refusal and 1.3 ppm caused a significant depression in feed intake and rate of gain. No lesions attributable to vomitoxin were observed in pigs fed up to 43 ppm dietary vomitoxin for a 21-d period. Alterations in various blood serum characteristics were observed in pigs fed vomitoxin, however, the effects could not be separated from those that may result from low intake of food.

Determination of amino acid requirements of young pigs using an indicator amino acid.

Abstract: 1. Mixtures of skim milk and free amino acids were compared as diets for pigs which would allow manipulation of dietary amino acid levels. Piglets gained 208 g/d between 3 and 14 d of age on the skim-milk diet, but replacement of 600 g/kg of the dietary nitrogen with free amino acids reduced growth rate to 148 g/d.2. Supplementation of a lysine-deficient diet with lysine reduced the catabolism of [14C]phenylalanine showing that phenylalanine catabolism could be used as an indicator of the adequacy of diet with respect to another essential amino acid.3. The dietary level of phenylalanine which would provide an excess for catabolism by the piglet was estimated directly by measuring the influence of dietary phenylalanine level on [14C]phenylalanine oxidation. Reduction of the dietary phenylalanine level below 7 g/kg had no effect on phenylalanine oxidation, whereas increasing the dietary phenylalanine level above 7 g/kg resulted in a linear increase in phenylalanine oxidation.4. An indirect estimate of histidine requirement was made by examining the influence of dietary histidine level on [14C]phenylalanine oxidation. In diets containing more than 4 g histidine/kg, phenylalanine oxidation was minimal. In diets containing less than 4 g histidine/kg, [14C]phenylalanine oxidation increased as the level of dietary histidine was reduced. This showed that the utilization of the essential amino acid phenylalanine, for protein synthesis, was not limited by histidine supply in diets containing more than 4 g histidine/kg.5. A direct estimate of histidine requirement was made by examining the influence of dietary histidine level on [14C]histidine oxidation. Diets with more than 4 g histidine/kg contained an excess which was catabolized: there was a linear increase in histidine oxidation in response to dietary histidine levels greater than 4 g/kg. This confirmed the previous indirect estimate of histidine requirement.

Effect of increased dietary carbohydrate on selenium metabolism and toxicity in rainbow trout (Salmo gairdneri).

Abstract: Juvenile trout were reared on either a high available carbohydrate (HC) or low available carbohydrate (LC) diet supplemented with from 0 to 10 micrograms selenium per gram of diet for 16 weeks, to determine if excess liver glycogen deposition affected the metabolism and toxicity of dietary selenium. Trout reared on the HC diet with 10 micrograms selenium per gram diet first demonstrated signs of selenosis and had significantly higher (P less than 0.05) liver selenium levels than trout reared on the LC diet with 10 micrograms selenium per gram diet after 16 weeks, indicating that excess dietary carbohydrate enhances dietary selenium toxicity in trout. The mechanism of the interaction is unclear since neither selenium elimination rates nor carcass and kidney selenium levels were affected by the dietary carbohydrate level. Trout reared on high dietary selenium diets (10 micrograms/g) had an increased incidence of renal calcinosis. In addition, liver copper levels were significantly affected by both dietary selenium and liver glycogen content indicating a significant copper-selenium and copper-glycogen interaction in trout. The development of renal calcinosis and the copper interactions suggest a variety of toxic effects of selenium on trout that may all be responsible for the observed changes in growth and feed efficiency.

Effect of Nitrite and Salt on the Color, Flavor and Overall Acceptability of Ham

Abstract: Effect of nitrite and salt on color, flavor and overall accpetability of ham was examined. Semitendinosus pork muscles were cured with four levels of nitrite (0, 50, 100 and 150 ppm) and three levels of salt (0, 1 and 2%). Nitrite content decreased after processing and salt remained constant. The Semitendinosus muscle became darker, redder and more intensely colored as measured on the Hunterlab colorimeter. Also the increased redness was detected by panelists as nitrite increased. Cured meat flavor intensity increased with increasing salt and nitrite, with salt having the greater effect. Panelists' perceptions of saltiness and sweetness were most affected by level of salt. The sample containing 50 ppm nitrite was acceptable to untrained panel.

Grain-Size Characteristics of Sediment Transported During Dust Storms

Abstract: The grain-size characteristics of sediment transported by wind in creep, saltation, and suspension during 15 dust storms in the Slims River Valley, Yukon Territory, were investigated. Grain-size analysis of the transported sediment indicated that the suspended sediment is significantly finer and better sorted than the sediment transported in either surface creep or saltation. The data also show that during dust storms the mean particle size of the suspended sediment decreases as a power function of height. The grain size distributions of the sediment transported in suspension and surface creep are characterized by strong positive skewness, which results from the selective removal of surface particles small enough to be transported by the wind at a given velocity. In contrast, the grai -size distribution of the saltation samples are negatively skewed, which is thought to result from the selective removal of the finer particles into suspension from those particles initially lifted from the surface into the air stream. Thus the proportion of sediment initially entrained into the air stream which returns to the surface in saltation will lack the fine grains removed in suspension and will therefore tend to be less positively or negatively skewed.

Calculation of particle trajectories in the presence of a gradient in turbulent-velocity variance

Abstract: Recent papers by Wilson et al. (1981b) and Legg and Raupach (1982) give methods for the calculation of particle trajectories in turbulence with a gradient in vertical velocity variance Σ2w. However the two methods seem contradictory.

Prototyping interactive information systems

Abstract: Applying prototype-oriented development processes to computerized application systems significantly improves the likelihood that useful systems will be developed and that the overall development cycle will be shortened. The prototype development methodology and development tool presented here have been widely applied to the development of interactive information systems in the commercial data processing setting. The effectiveness and relationship to other applications is discussed.

The Effect of Differential Amounts of Positive Verbal Feedback on the Intrinsic Motivation of Male Hockey Players

Abstract: The purpose of this study was to assess the relationship between the amount of positive verbal feedback presented and the ensuing intrinsic motivation of male hockey players toward a hockey-related task. The subjects were 50 male hockey players 13-16 years of age who performed on an interesting task consisting of 24 slides that allowed the subject to test his decision-making abilities in simulated hockey situations. Subjects performed on the task and received either 6, 12, 18, 24 (on every trial or slide), or no positive verbal reinforcements regarding their performance. Following their participation on the task, subjects answered an intrinsic motivation questionnaire and a question on feelings of competence. Results indicated that subjects receiving positive verbal feedback displayed a much higher level of intrinsic motivation and experienced higher levels of feelings of competence than subjects in the control group, irrespective of the amount of feedback presented. Further, no other differences were fou...

Fish assemblages in a river with unusual gradient (Luongo, Africa-Zaire system), reflections on river zonation, and description of another new species

Abstract: Fish distribution in a river within the drainage system of Zaire headwaters and with an unusual gradient was studied. The Luongo River has high gradient upper and lower sections, separated by a long middle section of no gradients, and bordered by rapids and waterfalls. On the basis of Luongo's hydrographic history, topography and fish taxocenes the river is divided into saltatory zones, each zone inhabited by separate homeostatic fish communities. The problem of river natural zonation is argued. Luongo River is, furthermore, unique for its high richness (49 species), biogeographical correlations, and the number of undescribed species found (14%), of which one,Chetia mola, is described in this study. The probable reasons for the richness and for the discontinuous fish assemblages are discussed.

Dehydration Injury in Germinating Soybean (Glycine max L. Merr.) Seeds.

Abstract: The sensitivity of soybean (Glycine max L. Merr. cv Maple Arrow) seeds to dehydration changed during germination. Seeds were tolerant of dehydration to 10% moisture if dried at 6 hours of imbibition, but were susceptible to dehydration injury if dried at 36 hours of imbibition. Dehydration injury appeared as loss of germination, slower growth rates of isolated axes, hypocotyl and root curling, and altered membrane permeability. Increased electrolyte leakage due to dehydration treatment was observed only from isolated axes but not from cotyledons, suggesting that cotyledons are more tolerant of dehydration. The transition from a dehydration-tolerant to a dehydration-susceptible state coincided with radicle elongation. However, the prevention of cell elongation by osmotic treatment in polyethylene glycol (−6 bars) or imbibition in 20 micrograms per milliliter cycloheximide did not prevent the loss of dehydration tolerance suggesting that neither cell elongation nor cytoplasmic protein synthesis was responsible for the change in sensitivity of soybean seeds to dehydration. Furthermore, the rate of dehydration or rate of rehydration did not alter the response to the dehydration stress.

Number of Generations, Egg Production, and Developmental Time of Culex Pipiens and Culex Restuans (Diptera: Culicidae) in Southern Ontario

Abstract: Culex pipiens and Cidex restuans each had 3 major generations per year during 1978, 1979, and 1980 in southern Ontario, Canada. Eggs of the 1st generation were laid from mid-May to mid-June, the 2nd from mid-June to mid-July, and the 3rd from mid-July to early August. A small 4th generation occurred during August. The 3rd generation of Cx. pipiens and the 2nd of Cx. restuans were usually the largest. Overwintered females of Cx. pipiens and Cx. restuans produced fewer eggs per raft than females of the summer generations, although egg production declined in late summer. Temperature during ovarian development did not affect egg production; however, the development of Cx. pipiens larvae at high densities reduced egg production. The rates of embryonic, larval and pupal development were correlated positively with temperature, although larval and pupal development was negatively correlated with larval density. Water temperature was more important than density in influencing the developmental rate of Cx. pipiens larvae, although the opposite was true with Cx. restuans . Survival of larvae and pupae of each species was similar and depended on larval density and not temperature. Based on biological and epidemiological factors, the most efficient procedure to reduce the possibility of an outbreak of St. Louis encephalitis in Ontario is larval control from late May through July.

Examination of bioaccumulation and biomagnification of metals in a precambrian shield lake

Abstract: This paper reports on a comprehensive examination of metal levels at various trophic levels within an undisturbed Precambrian shield lake ecosystem Concentrations of 21 naturally occurring elements (Hg, Cu, Al, Ba, S, Ni, Cd, Ca, Be, Zn, P, Pb, Mg, Sr, Fe, V, Mo, Mn, Ti, B, Cc) were measured in sediments, clams, fish, birds and mammals Mercury was the only element to exhibit biomagnification in both aquatic and terrestial food chains The levels of several metals were elevated in fish-eating birds relative to concentrations observed in the fish Mercury was the only metal which accumulated in muscle tissue with increased age and size of all fish species tested The concentrations of a few other metals were correlated to fish length, but these relationships were not consistent between species

Niche Dynamics and Organization of Waterfowl Guilds in Variable Environments

Abstract: Factors influencing the diversity of coexisting ducks in the prairie—pothole region of North America were investigated. Thirty—five years of census data and data on breeding—habitat use for each of two guilds (diving and dabbling ducks) from aspen—parkland and mixed—prairie habitats were analyzed to investigate the means by which species were accommodated in diverse assemblages. There was a regular increase in the temporal variability of breeding habitats of each guild in this order: parkland divers < parkland puddle ducks < grassland divers < grassland puddle ducks. A positive relationship between a multivariate measure of niche separation derived from discriminant function analysis and species diversity, suggesting competitively induced adjustments to niche parameters, was found only for parkland diving ducks. Species diversity was better correlated with total niche space for guilds occupying more variable breeding habitats. Niche separation and species diversity were never inversely related, suggesting...