Showing papers by "University of Guelph published in 1969"
TL;DR: Benzyladenine applied to primary leaves of intact bean plants delayed the senescence of both the leaves and the entire shoot, and the levels of incorporation of labelled precursors into protein and RNA were enhanced.
Abstract: Benzyladenine (BA) applied to primary leaves of intact bean plants delayed the senescence of both the leaves and the entire shoot. The retardation of senescence was manifested in higher levels of chlorophyll, protein, RNA and ribonuclease activity at all stages of development. Also, the levels of incorporation of labelled precursors into protein and RNA were enhanced. The effect of BA was largely independent of light intensity and the compound did not act merely as a nitrogen source.
89 citations
TL;DR: One of the major problems confronting biologists is that of classifying organisms as discussed by the authors, which is usually done in a hierarchical manner, where organisms are grouped together into classes (called "taxa" by biologists) which are assumed to be incapable of significant subdivision; then, these classes are in turn grouped so that the members of a number of classes at the lowest level also form a class at the next higher level.
Abstract: One of the major problems confronting biologists is that of classifying organisms. This is usually done in a hierarchical manner. First, organisms are grouped together into classes (called 'taxa' by biologists) which are assumed to be incapable of significant subdivision; then, these classes are in turn grouped so that the members of a number of classes at the lowest level also form a class at the next higher level. This process is repeated until, at the highest level, all organisms are grouped into a very few large classes. The classes at what is usually the lowest level are called 'species', and it is primarily with these that we are concerned in this paper. Species give rise to two major problems. In the first place, one must decide on criteria for the inclusion (or exclusion) of a particular organism into a particular species. In the second place, one has to put such criteria of demarcation into practice. Obviously, the two problems are not entirely separate, since there would be little point in choosing criteria which were, for practical reasons, impossible to apply. However, here we shall ignore the second problem and discuss only the first. I believe that, in the course of the discussion, light will be shed not only upon the nature of the concepts used for biological classification, but upon scientific concepts in general.
65 citations
TL;DR: Ackerson et al. as mentioned in this paper found that rye can substitute for up to 20% of the corn of barley in a laying hen ration without any effect on egg production, and they further substantiated these reports with the chick.
58 citations
TL;DR: In this paper, a model is proposed to account for the anomalous effect of cations on the kinetics of electrode reactions, which is attributed to variation in the distance of closest approach to the electrode for the predominate cation in the double layer with both the cation's solvated radius and the field in the inner layer.
56 citations
TL;DR: The results supported the hypothesis linking toxicity with an involvement of the central nervous system, and it was demonstrated that healthy cockerels could tolerate a daily intake of 250 μg of DDT per day for an indefinite period of time without signs of toxicity.
56 citations
TL;DR: It was concluded that penetration tests of cellular products such as fruits studied by Bourne may involve shear and compression factors in products with strongly bound network structures, e.g. process cheese, where flow is the only major factor involved.
Abstract: Following the work of Bourne, penetration measurements were performed with two sets of punches. The first set had a constant area and various perimeters. The second set had a constant perimeter and various areas. At constant perimeter, the relationship between punch area and force was a straight line with process cheese, butter and margarine, the latter two going through the origin. At constant area, the relationship between punch perimeter and force was a straight line for process cheese, but no definite relation between punch perimeter and force was obtained with butter and margarine. The relationship between the nature of the curves and the physical structure of the food is discussed. It was concluded that penetration tests of cellular products such as fruits studied by Bourne may involve shear and compression factors. In products with strongly bound network structures, e.g. process cheese, the main factors are shear and flow. In products with weakly bound network structures, such as plastic fats, flow is the only major factor involved.
40 citations
TL;DR: It is concluded that ageing of dandelion leaves is associated with a deficiency of endogenous GA, and most of the GA from Taraxacum leaves moves with the Rf of GA3.
Abstract: The level of endogenous gibberellins (GAs) in leaf tissue of Taraxacum officinale was high during leaf growth and expansion but declined progressively during leaf senescence. In the chromatographic system used, most of the GA from Taraxacum leaves moves with the Rf of GA3. However, several other GAs were also effective in retarding senescence in Taraxacum leaves. It is concluded that ageing of dandelion leaves is associated with a deficiency of endogenous GA.
35 citations
TL;DR: Investigation of interaction between estimates of breeding values of dairy sires and ten contrasting herd environments in which their daughters made records found a highly significant interaction involving sire proofs and level of grain feeding in summer was found.
33 citations
TL;DR: It was concluded that high levels of ribonuclease and chlorophyllase activity are not linked directly with the degradation of RNA andchlorophyll during leaf senescence.
Abstract: The activities of two enzymes, ribonuclease and chlorophyllase were investigated during the senescence of leaves. Ribonuclease activities were measured in primary leaves of Phaseolus vulgaris, and related to the levels of nucleic acid, protein and chlorophyll. Similarly, changes in chlorophyllase activity during senescence of leaves of Raphanus sativus were measured and related to chlorophyll. During senescence the levels of each enzyme as well as its respective substrate declined. Retardation of senescence, by excision of young tissue from intact plants or by treatment of detached leaves with cytokinins resulted in a maintainace of both the substrate and enzyme levels. It was concluded that high levels of ribonuclease and chlorophyllase activity are not linked directly with the degradation of RNA and chlorophyll during leaf senescence.
33 citations
TL;DR: The cell to dendrite transition during Pb-Sb alloy solidification was characterized by a gradual and continuous change in the cell cross-section rather than by the sudden growth of periodic secondary branches as discussed by the authors.
30 citations
TL;DR: In this paper, the annihilation lineshape in a Ge(Li) spectrometer is shown to be sensitive to the presence of metallic defects introduced by plastic deformation or temperature.
TL;DR: The orange-coloured mycetome of the pear psylla contains two kinds of inclusions; one kind contains protein, and (by electron microscopy) tubule-like peripheral maculae, which are probably unusual, degenerate or aberrant microorganisms.
Abstract: The orange-coloured mycetome of the pear psylla, which comprises a cellular covering membrane, a number of mycetocytes and a central syncytium, contains two kinds of inclusions (micro-organisms-in the literature). As DNA could not be detected in them, their status as micro-organisms is questioned. Both kinds contain protein; one kind contains RNA, and (by electron microscopy) tubule-like peripheral maculae. In spite of their anomalous reactions, the inclusions are probably unusual, degenerate or aberrant microorganisms. The biosome theory is invoked in explanation.
TL;DR: St studies on multiplication of T. brucei and T. congolense showed that trypanosomes artificially maintained in mice multiply exclusively by longitudinal fission, which suggests that some of these forms were seen dividing and may be part of the developmental cycle in the vertebrate host.
Abstract: Studies on multiplication of T. brucei and T. congolense showed that trypanosomes artificially maintained in mice multiply exclusively by longitudinal fission. T. brucei and T. congolense in a rabbit and a guinea-pig as well as in sheep has, in addition to multiplication by binary fission, a developmental cycle which includes leishmanial, leptomonad, crithidial and multinucleated forms. Since some of these forms were seen dividing, we suggest that they may be part of the developmental cycle in the vertebrate host.
TL;DR: It appears that the reduction in nodulation and nitrogen fixation in birdsfoot trefoil is a result of plant damage and abnormal root growth caused by 2,4-DB application.
Abstract: Field trials carried out in 1965 and 1966 showed that 2,4-DB, alone or in combination with dalapon, reduced nodulation and tended to decrease the efficiency of nitrogen fixation in birdsfoot trefoil. Dalapon appeared to enhance the inhibitory action of 2,4-DB on nodulation. No obvious cytological differences could be detected in the nodules or in the isolated bacteroids of field-treated and untreated plants. Under growth chamber conditions, 2,4-DB drastically reduced trefoil growth and nodulation particularly in treatments where the herbicide came directly in contact with the plants. It appears that the reduction in nodulation and nitrogen fixation is a result of plant damage and abnormal root growth caused by 2,4-DB application.
TL;DR: The enzyme phloretin hydrolase was purified from cells of E. herbicola Y46 grown on Yeast Beef Broth, by treatment of crude extracts with protamine sulfate, ammonium sulfate precipitation, elutions from calcium phosphate gel, elution from diethylaminoethyl-cellulose, and concentration by ultrafiltration.
Abstract: Erwinia herbicola Y46 degrades phloridzin to yield phloretin, phloroglucinol, and phloretic acid, when grown on defined medium containing phloridzin as the sole source of carbon. The identities of the intermediates isolated from culture filtrates were established by co-chromatography and by ultraviolet absorption spectra. Only 3 of 11 strains of this species, and none of the 12 species of bacterial phytopathogens tested could effect this breakdown. Some of the latter organisms possessed beta-glucosidase activity which liberated d-glucose from phloridzin. The enzyme phloretin hydrolase was purified from cells of E. herbicola Y46 grown on Yeast Beef Broth, by treatment of crude extracts with protamine sulfate, ammonium sulfate precipitation, elution from calcium phosphate gel, elution from diethylaminoethyl-cellulose, and concentration by ultrafiltration. The final preparation was free of beta-glucosidase, had a specific activity of 213 units per mg of protein, and represented a 142-fold purification over the crude extract. The enzyme had a pH optimum of 6.7 to 6.8, and produced only phloroglucinol and phloretic acid as products of phloretin breakdown, there being an equimolar relationship between the cleavage of phloretin and the formation of the products. The Michaelis constant (K(m)) for the enzyme with phloretin as substrate was 3.8 x 10(-5)m, and the enzyme was sensitive to Hg(2+) and Cu(2+) ions. Phloroglucinol, phloretic acid, p-chloromercuribenzoate and iodoacetamide were without effect on the activity. The enzyme did not react with phloridzin, naringin, or naringenin. The physiological significance of the results is discussed.
TL;DR: In this article, the peeling difficulty of hard-cooked eggs was investigated and it was found that the difficulty persisted until approximately pH 8.9, the critical range of pH.
TL;DR: The Progressive Fish-Culturist: Vol. 31, No. 2, pp. 90-93 as mentioned in this paper discusses the effects of aeromonas Salmonicida on amphibians.
Abstract: (1969). Habitat and Viability Studies on Aeromonas Salmonicida, Causative Agent of Furunculosis. The Progressive Fish-Culturist: Vol. 31, No. 2, pp. 90-93.
TL;DR: A commercial strain of large white turkey was fed maize‐soybean meal type rations from 8 to 21 (for hens) and 23 weeks of age (for toms) and its specific gravity determined, and the quantity of fat in skin taken from the dorsal surface determined.
Abstract: Synopsis A commercial strain of large white turkey was fed maize‐soybean meal type rations from 8 to 21 (for hens) and 23 weeks of age (for toms). During the developing period (8–18 weeks) each sex was offered diets having either a “high” or “low” energy concentration. To assure energy as the only dietary variable while con‐comitantly effecting a reasonable separation in caloric density, 3 per cent tallow was substituted by an equal amount of cellulose. At 18 weeks of age, the birds representing each of the developing period treatments, were subdivided into 3 further groups and subsequently offered the experimental finishing rations. These terminal diets, through the use of tallow, glucose and cellulose, were altered in energy content (2202, 2642, and 3083 kcal ME/kg) and respectively rated “low”, “moderate” and “high” in caloric concent. All birds were slaughtered, their specific gravity determined, and the quantity of fat in skin taken from the dorsal surface determined. Though there was a reduced weigh...
TL;DR: The 6-PGD patterns observed in this study resemble those found in other species, and three phenotypes were observed: a single fast band, a single slow band and a triple band composed of fast, slow and intermediate hands.
Abstract: Genetically controlled variants of 6-phosphogluconic dehydrogenase (6-PGD) have been described by many workers since first reported by FILDES and PARR in 1963 [Z]. Inherited electrophoretic patterns of this enzyme in red cell haemolysates have been detected in humans [4], rats [4], deer mice [S], cats [6], Drosophila [3] and pigeons [3]. Using the methods of FILDES and PARR [2], we have found 6-PGD polymorphism in the pig. Three herds of pigs were studied: a Canadian herd from Macdonald College, Quebec, composed of Yorkshire, Landrace, Lacombe and Large Black breeds; the Ontario Veterinary College (O.V.C.) blood group panel of pigs, including the breeds mentioned above and Hampshire, Tamworth and Berkshire breeds, and the pigs used for the European Pig Blood Group Comparison test, which were German Improved Landrace, German Improved Landrace/German Large White crosses, Gottingen Miniature and Pietrain breeds. The 6-PGD patterns observed in this study resemble those found in other species. Three phenotypes were observed: a single fast band, a single slow band and a triple band composed of fast, slow and intermediate hands. The migration of the 6-PGD components is toward the anode. These phenotypes are designated PGD A, PGD B and PGD AB (fig. 1). Table I shows the inheritance of the 6-PGD variants in 15 litters. Matings between PGD A individuals produce PGD A offspring, proving the parents to be homozygous for PGDA. No litters from
TL;DR: A study in the laboratory has confirmed the work of the above authors with regards to low egg production and small egg size and attempts to improve the nutrient requirements for growth and egg production of the dwarf birds.
TL;DR: Electrophoretic investigation of the perinatal development of hepatic and renal esterases showed that the increased enzyme activity was predominantly of microsomal origin.
TL;DR: In this article, the authors examined the role that convenience plays in food choices, in particular, studies looking at the role of convenience in relation to full meal preparation and/or consumption, and the individual characteristics of consumers and how they value these dimensions.
Abstract: It is evident that convenience plays a prominent role in the food choices of today’s consumers. A trend having begun throughout the Western world, consumer demand for convenience foods is now on the rise around the globe. The growing presence of drive-thru windows, microwave dinners, take-out meals, home delivery for groceries and internet shopping, all demonstrate the importance of convenience in determining food choices. Costa et al. have argued that convenience itself determines where, when, why, what, how, and even with whom we eat. Several studies have examined the role that convenience plays in determining food choices, in particular, studies looking at the role of convenience in relation to full meal preparation and/ or consumption.The two areas of investigation will be 1) the dimensions of convenience as a part of the meal preparation and consumption processe, and 2) the individual characteristics of consumers and how they value these dimensions.
TL;DR: Infective forms of T. brucei present in the liver and spleen of infected mice can pass through filters of pore size 0.8–1 μ diameter, however, the infective forms present in in the blood of these same mice can passed through filter sizes 3 μ or larger.
Abstract: Infective forms of T. brucei present in the liver and spleen of infected mice can pass through filters of pore size 0.8–1 μ diameter. However, the infective forms present in the blood of these same mice can pass through filters of pore size 3 μ or larger. Tissue forms were found in the spleen and liver of mice inoculated with infective tissue filtrates 72 hours after inoculation, while blood forms were present 24 hours after inoculation. However, if blood forms were inoculated into mice, tissue forms were present in spleen and liver in about 24 hours.
TL;DR: A distinct overlap between the breeding season and the moult period was observed and the significance of this is discussed in the light of recent metabolic studies and studies of moult.
Abstract: As part of a study of the European Goldfinch Carduelis carduelis near Melbourne, Victoria, the annual moult was observed in 512 birds between January 1963 and February 1965. The moult period occurred between December and May with the peak of activity in February and March. The moult sequence is discussed and is essentially similar to the normal passerine pattern with the exception of the tail moult. A distinct overlap between the breeding season and the moult period was observed. The significance of this is discussed in the light of recent metabolic studies and studies of moult.
TL;DR: The current study was conducted to determine the association between the bursa of Fabricius and the incidence of Marek’s disease in the domestic chicken.
TL;DR: Excessive mechanical action has little permanent softening effect on plastic fats, and little remained after 8 days storage of margarine and butter.
Abstract: The work-softening of margarine and butter resulting from passage through perforated plates was determined Various plates were used differing in size and number of perforations, but identical in the total area of perforations Greater work-softening was obtained with plates having many small perforations, but the back-pressure in the equipment was higher Passing the product through two or three plates slightly increased work softening Additional mechanical action was provided by a propeller rotating immediately behind the perforated plates Only small additional work-softening was obtained by this action and little remained after 8 days storage Increasing the speed of the propeller up to 100 rpm increased work softening Increasing it to 300 rpm did not further increase work softening It appears that excessive mechanical action has little permanent softening effect on plastic fats
TL;DR: A simultaneous increase of RNA and RNase in maturing tissue and a decrease during senescence suggests that the enzyme activity is correlated with the rate of ‘turnover’ of RNA rather than the absolute levels of RNA present in the tissue.
Abstract: The levels of the enzyme ribonuclease (RNase) were determined in primary leaves of Phaseolus vulgaris in an attempt to correlate changes in RNA with maturation and senescence. RNase, RNA and chlorophyll levels increased in expanding and maturing tissue and subsequently declined in senescing tissue. Senescence of the primary leaves started with the onset of flowering. A simultaneous increase of RNA and RNase in maturing tissue and a decrease during senescence suggests that the enzyme activity is correlated with the rate of‘turnover’of RNA rather than the absolute levels of RNA present in the tissue.