Showing papers by "Agriculture and Agri-Food Canada published in 1987"

Greatly Accelerated Microbial Degradation of Aldicarb in Re-treated Field Soil, in Flooded Soil, and in Water

Abstract: Two successive annual applications of aldicarb, as subsurface band-in-row soil treatments at 4 kg (AI)/ha in the same field plots, resulted in development of strains of microorganisms that rapidly broke down aldicarb in acid mineral soils of pH above ca. 6.0. Concentration and time required for breakdown for laboratory applications of 10–750 μg (AI)/g (ppm) of soil were positively correlated. Breakdown of these concentrations ranged from 1 to ca. 14 days. Concentrations higher than ca. 800 ppm appeared to retard bacterial action and inhibited fungal growth in the soil. A 5,000-ppm application inhibited fungal growth for > 6 months and retarded growth during the following 6–8 months. Toxic residues from 2,000- to 5,000-ppm applications persisted for 6 months to 1 year or more in the moist soil but degraded faster in flooded soil. Breakdown of repeated 50- or 100-ppm applications was most rapid in alkaline and near-neutral acidic soil or water media, much slower at pH levels near 6.0, and negligible at pH levels below ca. 5.6. Rate of accelerated microbial degradation depended on pH and moisture content of the soil, amount applied per treatment, numbers of treatments, and time period between treatments of aldicarb.

Peroxidase-labelled monoclonal antibodies for use in enzyme immunoassay.

Abstract: Desirable characteristics of enzyme-antibody conjugates for use in enzyme immunoassay are labelling uniformity, permanent availability and stability. The use of monoclonal antibodies (MCABS) for preparation of enzyme conjugates, in place of poly-clonal antibodies, ensures labelling uniformity and permanent availability. The problem of stability still exists. Monoclonal antibody-horseradish peroxidase (McAB-HREQ) conjugates produced in our laboratory showed variable stability. After extensive testing of McAB-HRPO conjugates it became obvious that sodium borohydride, used as a reducing agent, did not result in the production of stable conjugates without enzyme pretreatment with fluorodinitrobenzene (FDNB). Ascorbic acid or ethanolamine used as the reducing agent, resulted in McAB-HRPO conjugates which were stable for periods of ten months or more when stored filter sterilized at 4°C.

Membrane alterations in winter rye and Brassica napus cells during lethal freezing and plasmolysis

Abstract: Cells fixed during freezing or plasmolysis were used to study membrane alterations in hardened and non-hardened Brassica napus suspension-cultured cells and rye leaf mesophyll cells. The plasmalemma in non-hardened rye mesophyll cells formed multilamellar vesicles during lethal freezing at high subzero temperatures (–5°C). These vesicles became highly condensed at lower subzero temperatures (–10°C). Conversely, cold-hardened rye mesophyll cells did not undergo membrane alterations at these temperatures. The results from plasmolysis of B. napus and rye mesophyll cells hardened by ABA at 25 °C and low temperature (2°C), respectively, verify the cell response to lethal freezing. Again there was a continuum of responses with 1 kmol m−3 balanced salt causing multilamellar protrusions. Appression of the plasmalemma against the tonoplast to form multilamellar vesicles and the invagination of these vesicles into the tonoplast were also observed in rye cells undergoing lethal plasmolysis. Increasing the plasmolysing solution to 3 kmol m−3 occasionally caused the formation of multilamellar vesicles on the cell surface of hardened rye mesophyll cells.

15N-determined effect of inoculation with N2 fixing bacteria on nitrogen assimilation in Western Canadian wheats

Abstract: A two-year field study was undertaken using 15N isotope techniques to differentiate between stimulation of N uptake and N2 fixation in Western Canadian cultivars of spring wheat (Triticum aestivum L emend Thell) and durum (T turgidum L emend Bowden) in response to inoculation with N2-fixing bacteria

The effect of spacing of seedpieces on yield, quality and economic value for processing of Shepody potatoes in Manitoba

Abstract: The effect of in-row seedpiece spacing on Shepody potatoes for processing was tested under dryland conditions in southern Manitoba over three growing seasons, 1982 to 1984. Four seedpiece spacings, 22, 30, 38, and 46 cm were evaluated in two trials each year, one harvested as an early maincrop and the other as a maincrop.

Nepoviruses of the Americas

Abstract: The idea that plant viruses spread through the soil and infect healthy plants via the roots is nearly as old as the concept of viruses as causal agents of plant diseases. The first experimental proof that soil-inhabiting nematodes may serve as vectors of plant viruses was not obtained until 1958 when Hewitt et al. (51) published their significant findings linking soil transmission of grapevine fanleaf virus with the feeding of the ectoparasitic nematode Xiphinema index. This publication stimulated similar experiments on other soil-borne viruses, and by the early 1960s, several viruses with similar biological and physical properties were shown to have species of Xiphinema or Longidorus as vectors. In addition to grapevine fanleaf, the initial group of viruses with nematode vectors included tobacco ringspot, tomato ringspot, arabis mosaic, raspberry ringspot, strawberry latent ringspot, and tomato black ring. These viruses were indistinguishable morphologically and they were either serologically unrelated to each other or distantly related. Cadman (13) recognized that the viruses involved had close natural affinities and he proposed the group name NEPO viruses as a meaningful abbreviation of their two distinctive properties: nematode transmission and polyhedral-shaped particles. This group name has withstood the test of time, and although officially reduced to lower case letters, it now constitutes one of the 26 plant virus groups recognized by the International Committee on Taxonomy of Viruses (75).

The chemistry of a termite fungus comb

Abstract: The chemical and spectroscopic data presented herein show that about 50% of the weight of the termite fungus comb consists of carbohydrates (⊂40%) and proteinaceous materials (⊂10%). Of the remaining material about 30% appears to be aliphatic in nature (long-chain and branched alkanoic acids) and 20% aromatic and phenolic. The data on monosaccharide composition indicate that the fungus comb material, rich in glucose, arabinose and xylose, is predominantly of plant origin.

Virus-Free Potatoes Through Meristem Culture

Abstract: Among the common viruses that infect potato, some, like potato viruses A and Y, cause distinctive symptoms; others, like potato viruses M and S, are latent, causing no visible symptoms. These can be detected only by transmission to indicator plants, by electron microscopy or by serology. Others, like potato virus X and potato leaf roll, occur in strains of varying severity, some of which are latent. Viruses that cause foliar symptoms have been controlled by devising certification schemes that include periodic inspection and rogueing out abnormal plants. Until recently, however, latent viruses have been accepted, not only because detection was difficult, but also because no virus-free source plants were available, and techniques for virus eradication had not been developed. With the advent of nutrient culture of meristematic buds excised from heat-treated plants, developing virusfree plantlets from infected source plants became relatively easy and virus-free plants of most major cultivars are now available (see Mellor and Stace-Smith 1977).

Enzyme-linked immunosorbent assay on nitrocellulose membranes (dot-ELISA) in the serodiagnosis of plant pathogenic bacteria

Abstract: The usefulness of enzyme-linked immunosorbent assay on nitrocellulose membranes (dot-ELISA) for diagnosis and identification of plant pathogenic bacteria was tested. Five pathovars of Xanthomonas campestris and two antisera, one produced against pv. vesicatoria and the other against pv. translucens, were used in a model system. A 10-min incubation of the bacterial cells, dot blotted on membranes, in diluted sera, followed by either alkaline phosphatase conjugated protein A or goat antirabbit globulin, resulted in a specific reaction between the homologous serum and bacteria. Populations of 1000-2000 cfu per spot (ca. 0.3 cm2) could be detected with these reagents. The streptavidin-biotinylated peroxidase complex produced a definitive reaction with as few as 800 cfu, but cross-reactions became evident at the higher cell concentrations among all five pathovars in tests with both antisera. Cell-free extracts, obtained by centrifugation of boiled bacteria, reacted similarly to live cells. Unrelated bacteria did not react with either antiserum. Extracts of lesions from tomato and pepper leaves infected with X. campestris pv. vesicatoria reacted positively with the antiserum produced against this pathovar but not that produced with pv. translucens. Samples of supernatants from boiled lesions reacted with similar intensity as those from homogenized tissues.

Human body fluids - IUPAC proposed reference materials for trace elements analysis

Abstract: Interlaboratory cooperative studies have been conducted under the auspices of the IUPAC Commission on Toxicology to establish concentrations of biological important trace elements in commercially available lyophilized human serum, whole blood and urine. The main objective was to arrive at consensus concentration values in order to establish these materials as reference materials for chemical analysis. The analytical data presently available have been elaborated in collaboration among world-wide expert laboratories.

The effects of PSE/DFD conditions and frozen storage upon the processing yields of pork cuts

Abstract: A total of 163 hams, 181 boneless loins, 120 picnic shoulders and 120 boneless, skinned bellies were utilized to evaluate the effects of frozen storage and differences in inherent muscle quality on the processing yields of pork cuts under commercial conditions. The composite results of this study indicate that compared to fresh cuts, the use of frozen and thawed cuts for processing substantially reduced total processing yields (1.7 to 5.2% in hams, 4.4 to 14.3% in backs, 1.3 to 2.0% in picnics and 2.2 to 2.7% in bellies), depending upon the inherent muscle quality. Differences in inherent muscle quality have also been shown to substantially affect the total processing yields of various fresh (up to 7.7% in hams, 10.7% in backs, 4.8% in picnics and 0.5% in bellies) and frozen and thawed (up to 13.5% in hams, 20.5% in backs, 4.6% in picnics and 0.9% in bellies) cuts, despite the fact that the differences in bellies were insufficient in magnitude to be statistically significant. Therefore, the results of this study clearly indicate that both the inherent muscle quality of cuts and the decision to use frozen and thawed cuts for processing can materially influence the profitability of pork processing operations.

Population Dynamics of Alfalfa Blotch Leafminer, Agromyza frontella (Diptera: Agromyzidae), in Eastern Ontario: Analysis of Numerical Change During the Colonization Phase

Abstract: Following its invasion of eastern Ontario during the mid-1970's, numbers of the alfalfa blotch leafminer, Agromyza frontella (Rondani), increased rapidly to economic proportions and then receded to near tolerable levels. Thirty-three life tables were compiled from population and mortality data collected during this colonization phase. Analysis of the components of mortality using a variance/covariance matrix of the separate mortalities, as expressed as k values, showed that maggot mortality within leaf mines was the key factor that determined population trends. Maggot mortality was the result of two contemporaneous processes fluctuating with a similar order of magnitude: exploitation and interference competition among instars, and predation by a complex of indigenous nabids and mirids. Although the former process was density dependent, its regulatory potential was damped by the inverse response of the predators, whose activity diminished the competitive interaction. Prepupal mortality was high but relatively invariant. Mortality from other causes was low and contributed little to population trend. Life tables for the larval stage in central Quebec resembled those for Ontario.

Neutral sugar analysis of polysaccharides from the seed epidermis ofBrassia campestris

Abstract: A mucilaginous material was extracted from the epidermal cells of seed ofBrassica campestris L. cv. Candle canola. Hydrolysis and gas chromatographic analysis showed that it contained the following neutral sugars: arabinose, rhamnose, glucose, mannose and galactose. Total hydrolysis of the extract was not realized. The residue contained carbohydrate, protein and lipid.

Sulfotepp in diazinon and other organophosphorus pesticides.

Abstract: The presence of the toxic impurity, sulfotepp (O,O,O',O'tetraethyl dithiopyrophosphate), in technical diazinon has been known since the introduction of diazinon in the marketplace as a broad spectrum insecticide (Martgot and Gysin 1957). Because of i ts tox ic i ty , sulfotepp as an impurity has been implicated in cases of human poisoning (Sovocool et al. 1981). Sulfotepp is also resistant to hydrolysis and therefore is a concern in disposal of waste or spilled diazinon (Dennis et al. 1980). Recently, levels of sulfotepp in micro-encapsulated formulations of diazinon manufactured in the U.S.A. have been determined (Karr 1985). I t was therefore fel t useful to examine other types of formulations, as well as technical diazinon, used in Canada to determine i f regulatory action may be required. Since sulfotepp has been shown to be formed during the manufacturing process (Karr 1985) and is not a hydrolysis product (Margot & Gysin 1957, Sovocool 1981) i t was decided to examine other technical organophosphorus pesticides for i ts presence. Wilkins et al. (1985) recently reported the presence of sulfotepp in demeton. Parathion has been shown to contain sulfotepp (Diggory et al. 1977, Greenhalgh et al. 1983).

Comparison of antibiotic tolerance, lipids and respiration in the tomato pathogens Fusarium oxysporum lycopersici and F. oxysporum radicis lycopersici

Abstract: The respiration and lipid contents and the tolerance to mycostatin, chloramphenicol and cycloheximide were compared in the two morphologically similar forms of the tomato pathogens: Fusarium oxysporum lycopersici (FOL) and the virulent form F. oxysporum radicis lycopersici (FORL). The differential tolerances to mycostatin were the most significant feature of the comparisons. The MIC for FORL was 24 μg/mL for the mycelium and 38 μg/mL for the spores. For FOL, the MIC was 8 ug/mL for both. This pattern of higher mycostatin tolerance by FORL obtained at 19°C and 27°C. There were differences between FOL and FORL in their fatty acid composition. FORL contained about three times as much C18:0 and over twice as much C18:1 as FOL. Conversely FOL contains over two times as much C16:1 as FORL. There appeared to be no significant differences between the respiration rates of the two pathogens. The data is discussed relative to their significance as the biochemical basis for examining pathogenicity and virule...