Nancy McLean | Dalhousie University (original) (raw)

Papers by Nancy McLean

International Journal of Fruit Science

Weed surveys provide the basis for weed management research in lowbush blueberry, but have not be... more Weed surveys provide the basis for weed management research in lowbush blueberry, but have not been conducted in Nova Scotia since 2001. Documented declines in herbicide efficacy, loss and/or acquisition of herbicide active ingredients, confirmation of herbicide-resistant weed biotypes, and documented vectoring of weed seeds by machinery necessitate a new weed survey. A total of 165 bearing year lowbush blueberry fields were surveyed from 2017 to 2019, within which approximately 211 weed species were identified. Most weed species were herbaceous perennial forbs (89 species) and woody perennials (50 species), followed by annual broadleaf (24 species) and perennial grass weeds (20 species). The remaining flora consisted of a range of ferns, biennials, sedges and rushes, and orchids. The most common weed species were red sorrel (Rumex acetosella L.), poverty oatgrass (Danthonia spicata L. Beauv.), haircap moss (Polytrichum commune Hedw.), hair fescue (Festuca filiformis Pourr.), narrow-leaved goldenrod (Euthamia graminifolia (L) Nutt.), tickle grass (Agrostis hyemalis (Walter) BSP.), woolly panicum (Panicum lanugosum Ell.), cow wheat (Melampyrum lineare Desr.), bunchberry (Cornus canadensis L.), and yellow hawkweed (Hieracium caespitosum Dumort). Increased occurrence of these weed species is likely the result of documented or observed reductions in hexazinone and terbacil efficacy, confirmation of triazine-resistant biotypes, and common occurrence of seeds of these weed species on machinery. Low crop prices have also caused reduced pronamide use, contributing to increased occurrence of hair fescue. Results are guiding future research priorities for weed management in lowbush blueberry.

The Journal of Applied Poultry Research

SUMMARY This experiment determined the effects of yellow expeller-pressed canola meal (Y-EPCM) re... more SUMMARY This experiment determined the effects of yellow expeller-pressed canola meal (Y-EPCM) residual oil (10 vs. 14%), meal heat treatment (+H: at 115°C for 25 min vs. –H: no heat treatment), and dietary enzyme (no enzyme, lipase, protease, carbohydrase) on the nitrogen-corrected apparent metabolizable energy (AMEn) value and amino acid (AA) digestibility for broilers. In total, 480 male day-old chicks were assigned to 16 dietary treatments (6 birds per cage, 5 replicate cages per treatment) in a completely randomized design in a 2 × 2 × 4 factorial arrangement from day 14 to 21, where residual oil, heat treatment, and enzyme were the main factors. All 3 factors in the experiment interacted to affect the AMEn, in which meals with 14% residual oil supplemented with carbohydrase had higher (P < 0.05) AMEn 3,451 ± 112 kcal/kg compared to non-supplemented meal 2,823 ± 112 kcal/kg. The AA digestibility coefficients ranged from 99% for tyrosine to 44% for cysteine across treatments....

Canadian Journal of Animal Science

Juncea meal (JM) has higher crude protein and energy and less fibre compared with canola meal (CM... more Juncea meal (JM) has higher crude protein and energy and less fibre compared with canola meal (CM) potentially making it more suited for inclusion in laying hen diets. The objective of this study was to compare the inclusion of JM to CM and soybean meal (SBM) in diets of white-shell egg laying hens on production performance and egg quality characteristics. Ten diets were fed to 360 Lohmann LSL-Lite laying hens over four feeding phases during the 48 wk trial. Diets consisted of a SBM control, 10% or 20% CM (CM-10 or CM-20), and 10% or 20% JM (JM-10 or JM-20) with or without a phytase and multicarbohydrase enzyme cocktail. Juncea meal-20 (JM-20) reduced body weight (P > 0.05) compared with SBM by 122 g hen −1 but was not different from CM. Feed consumption, egg production, feed efficiency, and mortality were unaffected by meal or enzyme inclusion (P > 0.05). Feeding CM or JM did not result in any commercially important changes to egg quality, and enzyme inclusion had no effect. Up to 20% CM and JM could be included in laying hen diets without detrimental effects on production performance and egg quality characteristics. Enzyme inclusion did not improve performance of meal types.

Canadian Journal of Animal Science

This experiment determined the effects of expeller pressed canola meal (EPCM) residual oil (10 vs... more This experiment determined the effects of expeller pressed canola meal (EPCM) residual oil (10 vs 14%) and heat treatment at 115 ºC for 25 minutes on the nitrogen-corrected apparent metabolizable energy (AMEn) value and amino acid (AA) digestibility for broilers. Day old male chicks (6 per cage) were fed 6 test diets (5 cages per diet) from 14 to 21 days using the substitution method in a 2x2 factorial design. Increasing EPCM oil content from 10 to 14% increased (P < 0.05) EPCM AMEn value by 287 kcal kg-1. There was heat treatment by oil level interaction (P < 0.05) on standardized ileal digestibility (SID) of arginine, isoleucine, leucine, lysine, phenylalanine, threonine, and valine for EPCM where heat treatment of the low oil EPCM reduced (P ≤ 0.0012) the digestibility of all these AA, but heat treatment of the high oil EPCM only reduced lysine digestibility. In conclusion, heat treatment of EPCM reduced its AMEn value and digestibility of some AA. The AA digestibility of EPCM with low oil were reduced more by heat treatment than EPCM with high oil content, implying that heat treatment negative effects on AA digestibility increases with a decrease in residual oil content in EPCM.

Weed Science, 2014

Biannual applications of hexazinone have been applied in many lowbush blueberry fields in Nova Sc... more Biannual applications of hexazinone have been applied in many lowbush blueberry fields in Nova Scotia for more than 30 years. Persistent reliance on a single herbicide chemistry may have selected for hexazinone-resistant red sorrel. The recommended rate of hexazinone (1.92 kg ai ha−1) no longer controls red sorrel in many growing regions. Six levels of hexazinone (0, 0.48, 0.96, 1.92, 3.84, and 7.68 kg ai ha−1) were applied to red sorrel plants grown in a greenhouse from seeds collected from three commercial fields and a no blueberry area to determine if they were hexazinone resistant. Red sorrel from two sites where hexazinone had not been applied regularly died at the 0.96 kg ai ha−1 rate of hexazinone whereas red sorrel from two commercial fields survived at 7.68 kg ai ha−1. It is concluded that red sorrel is hexazinone-resistant in some wild blueberry fields. A portion of the psbA gene was sequenced and it was determined that resistant plants had a Phe to Val substitution at pos...

TAG Theoretical and Applied Genetics, 1998

Red clover genotypes capable of regenerating plantlets in vitro from non-meristematic tissue-deri... more Red clover genotypes capable of regenerating plantlets in vitro from non-meristematic tissue-derived callus are rare. Selection for genotypes capable of somatic embryogenesis identified a clone comprised of a group of plantlets regenerated from a hypocotyl-derived callus culture on L2-based media and another group of plantlets originating from crown divisions of the epicotyl-derived plant. The callus-derived plants of this clone were

Plant Cell Reports, 1993

DNA fingerprints generated by the Jeffreys' probes, 33.6 and 33.15, indicated the presence of min... more DNA fingerprints generated by the Jeffreys' probes, 33.6 and 33.15, indicated the presence of minisatellite-like sequences in the red clover genome. The fingerprints generated by probe 33.6 gave less background and fewer but better defined bands than those obtained with probe 33.15. Assay of a regenerative somaclonal variant (F49R) by DNA fingerprinting with probe 33.6 detected mutation that was unlinked to the regenerative trait. The fingerprints obtained under the applied conditions also demonstrated genetic stability of consecutive generations of the regenerants in tissue culture. DNA fingerprints of F 1 plants revealed that each polymorphic band was inherited from either one or the other parent. Both probes distinguished individualspecific genotypes in seven cultivars of red c/over. Greater variability in DNA fingerprints was detected between (V=0.899) than within (0.417<V_<0.548) cultivars.

Euphytica, 1992

In earlier work on improvement of persistance in forage legumes, we selected genotypes from highl... more In earlier work on improvement of persistance in forage legumes, we selected genotypes from highly productive cultivars of alfalfa, Algonquin and Apica (Euphytica 45: 105-112, 1990) and cv. Florex red clover (Plant Cell Reports 8: 395-398, 1989) capable of in vitro regeneration from callus and cell culture. The alfalfa germplasm and its F1 progeny as well as an F2 red clover population were tested for cold stress tolerance. Plantlets were hardened in culture tubes at 2 or 5 ° C, 8 h photoperiod, for at least four weeks and then subjected to freezing temperatures,-16 or-10°C for alfalfa and red clover, respectively. Survival of regenerative genotypes was significantly higher than of the non-regenerative ones in both species. A strong positive correlation (r = 0.78) between the regenerative trait and plant survival was found in alfalfa. The experiments indicate that in vitro selection for regenerative trait may improve cold stress tolerance of alfalfa and red clover.

Canadian Journal of Soil Science, 2011

Halde, C., Hammermeister, A. M., McLean, N. L., Webb, K. T. and Martin, R. C. 2011. Soil compacti... more Halde, C., Hammermeister, A. M., McLean, N. L., Webb, K. T. and Martin, R. C. 2011. Soil compaction under varying rest periods and levels of mechanical disturbance in a rotational grazing system. Can. J. Soil Sci. 91: 957–964. In Atlantic Canada, data are limited regarding the effect of grazing systems on soil compaction. The objective of the study was to determine the effect of intensive and extensive rotational pasture management treatments on soil bulk density, soil penetration resistance, forage productivity and litter accumulation. The study was conducted on a fine sandy loam pasture in Truro, Nova Scotia. Each of the eight paddocks was divided into three rotational pasture management treatments: intensive, semi-intensive and extensive. Mowing and clipping were more frequent in the intensive than in the semi-intensive treatment. In the extensive treatment, by virtue of grazing in alternate rotations, the rest period was doubled than that of the intensive and semi-intensive trea...

Canadian Journal of Plant Science, 1997

Establishment of productive stands of birdsfoot trefoil (Lotus corniculatus L.) is often difficul... more Establishment of productive stands of birdsfoot trefoil (Lotus corniculatus L.) is often difficult due to poor seedling vigour. Objectives of this study were to evaluate the relative effectiveness of in vitro selection conditions for seedling vigour and to choose the best lines for further evaluation. Birdsfoot trefoil seedlings from cvs. Leo and Upstart were selected on the basis of in vitro rate of germination at 5, 12 and 20 °C and subsequent seedling growth at 20 °C. Two cycles of recurrent selection were carried out. Progeny from both cycles of selection were evaluated under controlled and field conditions. In general, selection temperatures did not significantly affect emergence, individual shoot dry matter production or total shoot dry matter production. Emergence and total shoot dry matter yield were higher for selections within cv. Upstart than for selections within cv. Leo. Seedling vigour of cycle-2 selections was not superior to cycle-1 selections. Failure to make gains ...

Avian Diseases, 2014

Endogenous retroviral elements (ERVs) are prolific components of the genomes of complex species, ... more Endogenous retroviral elements (ERVs) are prolific components of the genomes of complex species, typically occupying more sequence space than do essential, protein-encoding genes. Much of what we know today about the structure and function, as well as the evolution and pathogenic potential, of ERVs was fleshed out over several decades during the last century using the avian leukosis virus subgroup E-related (ALVE) family of endogenous retroviruses of chickens as a model system. A critical enabling factor in the elucidation of ALVE structure and function is the ability to detect and unambiguously identify specific ALVE proviral elements and to develop accurate element profiles for individual chickens under study. Currently, the most common approach for ALVE locus detection involves element-specific PCR assays carried out using primers that target host DNA near the insertion site of the provirus (i.e., the upstream and downstream flanks of the unoccupied site). Here we describe a new approach for proviral detection that exploits restriction enzyme sites in flanking DNA to develop ALVE element profiles more rapidly than with assays currently in use. Moreover, unlike element-specific PCR tests, the &amp;amp;amp;amp;amp;amp;amp;amp;quot;profiling&amp;amp;amp;amp;amp;amp;amp;amp;quot; assay detects novel ALVEs for which insertion sites have not yet been identified as well as previously characterized elements.

Cold hardiness and in vitro regeneration are closely related traits in selected alfalfa and red c... more Cold hardiness and in vitro regeneration are closely related traits in selected alfalfa and red clover germplasms. We investigated the cold-induction of three genes, MsaCIA, MsaCIB and MsaCIC, implicated in the cold tolerance of alfalfa, in non-regenerative and regenerative somaclonal variants of red clover by Northern blot analysis using alfalfa cDNA clones as hybridization probes. Only the MsaCIA gene exhibited increased steady-state mRNA levels in cold-acclimated red clover. We observed, however, enhanced-cold induction of steady-state levels of MsaCIA gene transcripts in all regenerative somaclonal variants compared to non-regenerative red clover lines. Moreover, these two traits, regeneration and enhanced cold-induction of MsaCIA, were concomitantly transmitted to progeny suggesting that enhanced expression of MsaCIA and the regenerative trait are either linked, or the expression of both traits are regulated by a 'master' gene whose expression is modified by somatic embryogenesis.

Annals of Botany

Red clover genotypes capable of regenerating plantlets in itro from non-meristem-derived callus a... more Red clover genotypes capable of regenerating plantlets in itro from non-meristem-derived callus are rare. A previous study identified a pair of near isogenic lines which were derived from a single seed but differed in regenerative ability. The callus-derived plants of this clone were highly regenerative when reintroduced to culture whereas the epicotylderived plants produced non-regenerative callus cultures. The objective of the present study was to observe meiotic chromosome pairing and to compare isozyme profiles and ferritin gene expression in regenerative and nonregenerative plants and cultures from the clone. Meiotic cells exhibited normal homologous chromosome pairing. Starch gel zymograms from glasshouse-grown regenerative (F49R) and non-regenerative (F49M) plants failed to show somaclonal variation for alcohol dehydrogenase, glutamate dehydrogenase, esterase or peroxidase. Isoelectric focusing of callus cultures from regenerative and non-regenerative plants revealed that regeneration was accompanied by a reduction in staining intensity and numbers of peroxidase bands compared to non-regenerative cultures. A unique cathodic peroxidase band (pI 7n6) was associated with non-regenerative cultures. Ferritin expression was greater in callus than in fresh petiole tissue. Ferritin expression remained high in non-regenerative callus cultures but declined in regenerative cultures as regeneration progressed.

Animal Feed Science and Technology, 2012

ABSTRACT

The Canadian Entomologist

Fluctuating bee (Hymenoptera: Apoidea) populations jeopardise pollination services. Nesting habit... more Fluctuating bee (Hymenoptera: Apoidea) populations jeopardise pollination services. Nesting habitat for solitary bees is potentially limited in many agroecosystems, but the provision of artificial nests could augment bee communities and the pollination services they provide. We investigated whether cavity-nesting bees (Hymenoptera: Megachilidae) in lowbush blueberry (Vaccinium angustifolium Aiton (Ericaceae)) fields would use artificial trap nests. Different nest designs were compared, as was nesting occupancy between fruit-bearing and vegetative fields. Milk carton nests had significantly more uptake by and emergence of Osmia Panzer and Megachile Latreille than wooden nests. Only 3% of wooden nests had at least one occupied nesting tube versus 73% of milk carton nests, with a total of 34% nesting tubes occupied. Bee emergence was significantly higher in nesting tubes from fruit-bearing fields than vegetative fields. Osmia and Megachile emergence was low from milk carton nests, with...

Poultry science, Jan 3, 2018

Experiments were conducted to evaluate the effectiveness of a lysozyme product (InovapureTM) (LP)... more Experiments were conducted to evaluate the effectiveness of a lysozyme product (InovapureTM) (LP) against E. coli penetrating eggshells. In the first microbiological experiment, 60 agar-filled eggs were inoculated with E. coli suspension, then fumigated with distilled water, 1.5% or 3.0% LP or a quaternary ammonium product (QA) at 0.125% for 10 min. In the second microbiological experiment, another 60 agar-filled eggs were fumigated with the same sanitizer treatments first, then inoculated with the E. coli suspension. Eggshells were candled and visual colonies were counted after 48 h incubation. An animal experiment was conducted to evaluate LP applied to the surface of 2080 broiler hatching eggs on hatching and growth performance. Hatching eggs were submerged in an E. coli suspension. After drip drying, eggs were randomly divided into four fumigation treatments, each with four subsets of 150 eggs. Fumigation treatments were the same as in the microbiological experiments. Eggs were ...

International Journal of Fruit Science

Weed surveys provide the basis for weed management research in lowbush blueberry, but have not be... more Weed surveys provide the basis for weed management research in lowbush blueberry, but have not been conducted in Nova Scotia since 2001. Documented declines in herbicide efficacy, loss and/or acquisition of herbicide active ingredients, confirmation of herbicide-resistant weed biotypes, and documented vectoring of weed seeds by machinery necessitate a new weed survey. A total of 165 bearing year lowbush blueberry fields were surveyed from 2017 to 2019, within which approximately 211 weed species were identified. Most weed species were herbaceous perennial forbs (89 species) and woody perennials (50 species), followed by annual broadleaf (24 species) and perennial grass weeds (20 species). The remaining flora consisted of a range of ferns, biennials, sedges and rushes, and orchids. The most common weed species were red sorrel (Rumex acetosella L.), poverty oatgrass (Danthonia spicata L. Beauv.), haircap moss (Polytrichum commune Hedw.), hair fescue (Festuca filiformis Pourr.), narrow-leaved goldenrod (Euthamia graminifolia (L) Nutt.), tickle grass (Agrostis hyemalis (Walter) BSP.), woolly panicum (Panicum lanugosum Ell.), cow wheat (Melampyrum lineare Desr.), bunchberry (Cornus canadensis L.), and yellow hawkweed (Hieracium caespitosum Dumort). Increased occurrence of these weed species is likely the result of documented or observed reductions in hexazinone and terbacil efficacy, confirmation of triazine-resistant biotypes, and common occurrence of seeds of these weed species on machinery. Low crop prices have also caused reduced pronamide use, contributing to increased occurrence of hair fescue. Results are guiding future research priorities for weed management in lowbush blueberry.

The Journal of Applied Poultry Research

SUMMARY This experiment determined the effects of yellow expeller-pressed canola meal (Y-EPCM) re... more SUMMARY This experiment determined the effects of yellow expeller-pressed canola meal (Y-EPCM) residual oil (10 vs. 14%), meal heat treatment (+H: at 115°C for 25 min vs. –H: no heat treatment), and dietary enzyme (no enzyme, lipase, protease, carbohydrase) on the nitrogen-corrected apparent metabolizable energy (AMEn) value and amino acid (AA) digestibility for broilers. In total, 480 male day-old chicks were assigned to 16 dietary treatments (6 birds per cage, 5 replicate cages per treatment) in a completely randomized design in a 2 × 2 × 4 factorial arrangement from day 14 to 21, where residual oil, heat treatment, and enzyme were the main factors. All 3 factors in the experiment interacted to affect the AMEn, in which meals with 14% residual oil supplemented with carbohydrase had higher (P < 0.05) AMEn 3,451 ± 112 kcal/kg compared to non-supplemented meal 2,823 ± 112 kcal/kg. The AA digestibility coefficients ranged from 99% for tyrosine to 44% for cysteine across treatments....

Canadian Journal of Animal Science

Juncea meal (JM) has higher crude protein and energy and less fibre compared with canola meal (CM... more Juncea meal (JM) has higher crude protein and energy and less fibre compared with canola meal (CM) potentially making it more suited for inclusion in laying hen diets. The objective of this study was to compare the inclusion of JM to CM and soybean meal (SBM) in diets of white-shell egg laying hens on production performance and egg quality characteristics. Ten diets were fed to 360 Lohmann LSL-Lite laying hens over four feeding phases during the 48 wk trial. Diets consisted of a SBM control, 10% or 20% CM (CM-10 or CM-20), and 10% or 20% JM (JM-10 or JM-20) with or without a phytase and multicarbohydrase enzyme cocktail. Juncea meal-20 (JM-20) reduced body weight (P > 0.05) compared with SBM by 122 g hen −1 but was not different from CM. Feed consumption, egg production, feed efficiency, and mortality were unaffected by meal or enzyme inclusion (P > 0.05). Feeding CM or JM did not result in any commercially important changes to egg quality, and enzyme inclusion had no effect. Up to 20% CM and JM could be included in laying hen diets without detrimental effects on production performance and egg quality characteristics. Enzyme inclusion did not improve performance of meal types.

Canadian Journal of Animal Science

This experiment determined the effects of expeller pressed canola meal (EPCM) residual oil (10 vs... more This experiment determined the effects of expeller pressed canola meal (EPCM) residual oil (10 vs 14%) and heat treatment at 115 ºC for 25 minutes on the nitrogen-corrected apparent metabolizable energy (AMEn) value and amino acid (AA) digestibility for broilers. Day old male chicks (6 per cage) were fed 6 test diets (5 cages per diet) from 14 to 21 days using the substitution method in a 2x2 factorial design. Increasing EPCM oil content from 10 to 14% increased (P < 0.05) EPCM AMEn value by 287 kcal kg-1. There was heat treatment by oil level interaction (P < 0.05) on standardized ileal digestibility (SID) of arginine, isoleucine, leucine, lysine, phenylalanine, threonine, and valine for EPCM where heat treatment of the low oil EPCM reduced (P ≤ 0.0012) the digestibility of all these AA, but heat treatment of the high oil EPCM only reduced lysine digestibility. In conclusion, heat treatment of EPCM reduced its AMEn value and digestibility of some AA. The AA digestibility of EPCM with low oil were reduced more by heat treatment than EPCM with high oil content, implying that heat treatment negative effects on AA digestibility increases with a decrease in residual oil content in EPCM.

Weed Science, 2014

Biannual applications of hexazinone have been applied in many lowbush blueberry fields in Nova Sc... more Biannual applications of hexazinone have been applied in many lowbush blueberry fields in Nova Scotia for more than 30 years. Persistent reliance on a single herbicide chemistry may have selected for hexazinone-resistant red sorrel. The recommended rate of hexazinone (1.92 kg ai ha−1) no longer controls red sorrel in many growing regions. Six levels of hexazinone (0, 0.48, 0.96, 1.92, 3.84, and 7.68 kg ai ha−1) were applied to red sorrel plants grown in a greenhouse from seeds collected from three commercial fields and a no blueberry area to determine if they were hexazinone resistant. Red sorrel from two sites where hexazinone had not been applied regularly died at the 0.96 kg ai ha−1 rate of hexazinone whereas red sorrel from two commercial fields survived at 7.68 kg ai ha−1. It is concluded that red sorrel is hexazinone-resistant in some wild blueberry fields. A portion of the psbA gene was sequenced and it was determined that resistant plants had a Phe to Val substitution at pos...

TAG Theoretical and Applied Genetics, 1998

Red clover genotypes capable of regenerating plantlets in vitro from non-meristematic tissue-deri... more Red clover genotypes capable of regenerating plantlets in vitro from non-meristematic tissue-derived callus are rare. Selection for genotypes capable of somatic embryogenesis identified a clone comprised of a group of plantlets regenerated from a hypocotyl-derived callus culture on L2-based media and another group of plantlets originating from crown divisions of the epicotyl-derived plant. The callus-derived plants of this clone were

Plant Cell Reports, 1993

DNA fingerprints generated by the Jeffreys' probes, 33.6 and 33.15, indicated the presence of min... more DNA fingerprints generated by the Jeffreys' probes, 33.6 and 33.15, indicated the presence of minisatellite-like sequences in the red clover genome. The fingerprints generated by probe 33.6 gave less background and fewer but better defined bands than those obtained with probe 33.15. Assay of a regenerative somaclonal variant (F49R) by DNA fingerprinting with probe 33.6 detected mutation that was unlinked to the regenerative trait. The fingerprints obtained under the applied conditions also demonstrated genetic stability of consecutive generations of the regenerants in tissue culture. DNA fingerprints of F 1 plants revealed that each polymorphic band was inherited from either one or the other parent. Both probes distinguished individualspecific genotypes in seven cultivars of red c/over. Greater variability in DNA fingerprints was detected between (V=0.899) than within (0.417<V_<0.548) cultivars.

Euphytica, 1992

In earlier work on improvement of persistance in forage legumes, we selected genotypes from highl... more In earlier work on improvement of persistance in forage legumes, we selected genotypes from highly productive cultivars of alfalfa, Algonquin and Apica (Euphytica 45: 105-112, 1990) and cv. Florex red clover (Plant Cell Reports 8: 395-398, 1989) capable of in vitro regeneration from callus and cell culture. The alfalfa germplasm and its F1 progeny as well as an F2 red clover population were tested for cold stress tolerance. Plantlets were hardened in culture tubes at 2 or 5 ° C, 8 h photoperiod, for at least four weeks and then subjected to freezing temperatures,-16 or-10°C for alfalfa and red clover, respectively. Survival of regenerative genotypes was significantly higher than of the non-regenerative ones in both species. A strong positive correlation (r = 0.78) between the regenerative trait and plant survival was found in alfalfa. The experiments indicate that in vitro selection for regenerative trait may improve cold stress tolerance of alfalfa and red clover.

Canadian Journal of Soil Science, 2011

Halde, C., Hammermeister, A. M., McLean, N. L., Webb, K. T. and Martin, R. C. 2011. Soil compacti... more Halde, C., Hammermeister, A. M., McLean, N. L., Webb, K. T. and Martin, R. C. 2011. Soil compaction under varying rest periods and levels of mechanical disturbance in a rotational grazing system. Can. J. Soil Sci. 91: 957–964. In Atlantic Canada, data are limited regarding the effect of grazing systems on soil compaction. The objective of the study was to determine the effect of intensive and extensive rotational pasture management treatments on soil bulk density, soil penetration resistance, forage productivity and litter accumulation. The study was conducted on a fine sandy loam pasture in Truro, Nova Scotia. Each of the eight paddocks was divided into three rotational pasture management treatments: intensive, semi-intensive and extensive. Mowing and clipping were more frequent in the intensive than in the semi-intensive treatment. In the extensive treatment, by virtue of grazing in alternate rotations, the rest period was doubled than that of the intensive and semi-intensive trea...

Canadian Journal of Plant Science, 1997

Establishment of productive stands of birdsfoot trefoil (Lotus corniculatus L.) is often difficul... more Establishment of productive stands of birdsfoot trefoil (Lotus corniculatus L.) is often difficult due to poor seedling vigour. Objectives of this study were to evaluate the relative effectiveness of in vitro selection conditions for seedling vigour and to choose the best lines for further evaluation. Birdsfoot trefoil seedlings from cvs. Leo and Upstart were selected on the basis of in vitro rate of germination at 5, 12 and 20 °C and subsequent seedling growth at 20 °C. Two cycles of recurrent selection were carried out. Progeny from both cycles of selection were evaluated under controlled and field conditions. In general, selection temperatures did not significantly affect emergence, individual shoot dry matter production or total shoot dry matter production. Emergence and total shoot dry matter yield were higher for selections within cv. Upstart than for selections within cv. Leo. Seedling vigour of cycle-2 selections was not superior to cycle-1 selections. Failure to make gains ...

Avian Diseases, 2014

Endogenous retroviral elements (ERVs) are prolific components of the genomes of complex species, ... more Endogenous retroviral elements (ERVs) are prolific components of the genomes of complex species, typically occupying more sequence space than do essential, protein-encoding genes. Much of what we know today about the structure and function, as well as the evolution and pathogenic potential, of ERVs was fleshed out over several decades during the last century using the avian leukosis virus subgroup E-related (ALVE) family of endogenous retroviruses of chickens as a model system. A critical enabling factor in the elucidation of ALVE structure and function is the ability to detect and unambiguously identify specific ALVE proviral elements and to develop accurate element profiles for individual chickens under study. Currently, the most common approach for ALVE locus detection involves element-specific PCR assays carried out using primers that target host DNA near the insertion site of the provirus (i.e., the upstream and downstream flanks of the unoccupied site). Here we describe a new approach for proviral detection that exploits restriction enzyme sites in flanking DNA to develop ALVE element profiles more rapidly than with assays currently in use. Moreover, unlike element-specific PCR tests, the &amp;amp;amp;amp;amp;amp;amp;amp;quot;profiling&amp;amp;amp;amp;amp;amp;amp;amp;quot; assay detects novel ALVEs for which insertion sites have not yet been identified as well as previously characterized elements.

Cold hardiness and in vitro regeneration are closely related traits in selected alfalfa and red c... more Cold hardiness and in vitro regeneration are closely related traits in selected alfalfa and red clover germplasms. We investigated the cold-induction of three genes, MsaCIA, MsaCIB and MsaCIC, implicated in the cold tolerance of alfalfa, in non-regenerative and regenerative somaclonal variants of red clover by Northern blot analysis using alfalfa cDNA clones as hybridization probes. Only the MsaCIA gene exhibited increased steady-state mRNA levels in cold-acclimated red clover. We observed, however, enhanced-cold induction of steady-state levels of MsaCIA gene transcripts in all regenerative somaclonal variants compared to non-regenerative red clover lines. Moreover, these two traits, regeneration and enhanced cold-induction of MsaCIA, were concomitantly transmitted to progeny suggesting that enhanced expression of MsaCIA and the regenerative trait are either linked, or the expression of both traits are regulated by a 'master' gene whose expression is modified by somatic embryogenesis.

Annals of Botany

Red clover genotypes capable of regenerating plantlets in itro from non-meristem-derived callus a... more Red clover genotypes capable of regenerating plantlets in itro from non-meristem-derived callus are rare. A previous study identified a pair of near isogenic lines which were derived from a single seed but differed in regenerative ability. The callus-derived plants of this clone were highly regenerative when reintroduced to culture whereas the epicotylderived plants produced non-regenerative callus cultures. The objective of the present study was to observe meiotic chromosome pairing and to compare isozyme profiles and ferritin gene expression in regenerative and nonregenerative plants and cultures from the clone. Meiotic cells exhibited normal homologous chromosome pairing. Starch gel zymograms from glasshouse-grown regenerative (F49R) and non-regenerative (F49M) plants failed to show somaclonal variation for alcohol dehydrogenase, glutamate dehydrogenase, esterase or peroxidase. Isoelectric focusing of callus cultures from regenerative and non-regenerative plants revealed that regeneration was accompanied by a reduction in staining intensity and numbers of peroxidase bands compared to non-regenerative cultures. A unique cathodic peroxidase band (pI 7n6) was associated with non-regenerative cultures. Ferritin expression was greater in callus than in fresh petiole tissue. Ferritin expression remained high in non-regenerative callus cultures but declined in regenerative cultures as regeneration progressed.

Animal Feed Science and Technology, 2012

ABSTRACT

The Canadian Entomologist

Fluctuating bee (Hymenoptera: Apoidea) populations jeopardise pollination services. Nesting habit... more Fluctuating bee (Hymenoptera: Apoidea) populations jeopardise pollination services. Nesting habitat for solitary bees is potentially limited in many agroecosystems, but the provision of artificial nests could augment bee communities and the pollination services they provide. We investigated whether cavity-nesting bees (Hymenoptera: Megachilidae) in lowbush blueberry (Vaccinium angustifolium Aiton (Ericaceae)) fields would use artificial trap nests. Different nest designs were compared, as was nesting occupancy between fruit-bearing and vegetative fields. Milk carton nests had significantly more uptake by and emergence of Osmia Panzer and Megachile Latreille than wooden nests. Only 3% of wooden nests had at least one occupied nesting tube versus 73% of milk carton nests, with a total of 34% nesting tubes occupied. Bee emergence was significantly higher in nesting tubes from fruit-bearing fields than vegetative fields. Osmia and Megachile emergence was low from milk carton nests, with...

Poultry science, Jan 3, 2018

Experiments were conducted to evaluate the effectiveness of a lysozyme product (InovapureTM) (LP)... more Experiments were conducted to evaluate the effectiveness of a lysozyme product (InovapureTM) (LP) against E. coli penetrating eggshells. In the first microbiological experiment, 60 agar-filled eggs were inoculated with E. coli suspension, then fumigated with distilled water, 1.5% or 3.0% LP or a quaternary ammonium product (QA) at 0.125% for 10 min. In the second microbiological experiment, another 60 agar-filled eggs were fumigated with the same sanitizer treatments first, then inoculated with the E. coli suspension. Eggshells were candled and visual colonies were counted after 48 h incubation. An animal experiment was conducted to evaluate LP applied to the surface of 2080 broiler hatching eggs on hatching and growth performance. Hatching eggs were submerged in an E. coli suspension. After drip drying, eggs were randomly divided into four fumigation treatments, each with four subsets of 150 eggs. Fumigation treatments were the same as in the microbiological experiments. Eggs were ...