University of Guelph

About: University of Guelph is a education organization based out in Guelph, Ontario, Canada. It is known for research contribution in the topics: Population & Gene. The organization has 26542 authors who have published 50553 publications receiving 1715255 citations. The organization is also known as: U of G & Guelph University.

Sperm Apoptosis in Fresh and Cryopreserved Bull Semen Detected by Flow Cytometry and Its Relationship with Fertility

Abstract: The present study was conducted to detect sperm apoptosis in fresh and frozen semen and to determine its relationship with bull fertility. Three ejaculates were collected from five breeding bulls with different fertility levels and were cryopreserved using standard methods. Two flow cytometric methods were employed to measure apoptosis: an assay for phosphatidylserine (PS) translocation across the plasma membranes using fluorescein-labeled Annexin V and propidium iodide (PI), and an assay for nicked DNA using bromodeoxyuridine (BrdU), terminal deoxynucleotidyl transferase, and fluorescein-labeled anti-BrdU monoclonal antibody. Both assays showed that fresh sperm contained 10%-20% apoptotic sperm. Significant differences in the percentage of apoptotic sperm were observed among the bulls. Cryopreservation induced translocation of PS to the outer leaflet of the plasma membrane and caused most of the necrotic cells in fresh sperm to disintegrate. Bull fertility was significantly related to the percentage of necrotic or viable sperm in fresh semen as detected by the Annexin V/PI assay, to the number of apoptotic sperm in fresh semen as detected by the TUNEL assay, and to the level of chromatin or DNA condensation as detected by PI staining. The present study suggests that the presence of apoptotic spermatozoa in fresh semen could be one of the reasons for poor fertility in breeding bulls.

Footprint prediction of scalar fluxes using a Markovian analysis

Abstract: The contribution of upwind sources to measurements of vertical scalar flux density as a function of fetch (‘footprint’) is predicted using a Markovian simulation of fluid particle trajectories. Results suggest that both footprint peak position and magnitude change dramatically with surface roughness, thermal stability and observation levels. Results also indicate that the much used 100 to 1 fetch-to-height ratio grossly underestimates fetch requirements when observations are made above smooth surfaces, in stable conditions or at high observation levels.

Integration of DNA Barcoding Into An Ongoing Inventory of Complex Tropical Biodiversity

Abstract: Inventory of the caterpillars, their food plants and parasitoids began in 1978 for today's Area de Conservacion Guanacaste (ACG), in northwestern Costa Rica This complex mosaic of 120 000 ha of conserved and regenerating dry, cloud and rain forest over 0–2000 m elevation contains at least 10 000 species of non-leaf-mining caterpillars used by more than 5000 species of parasitoids Several hundred thousand specimens of ACG-reared adult Lepidoptera and parasitoids have been intensively and extensively studied morphologically by many taxonomists, including most of the co-authors DNA barcoding — the use of a standardized short mitochondrial DNA sequence to identify specimens and flush out undisclosed species — was added to the taxonomic identification process in 2003 Barcoding has been found to be extremely accurate during the identification of about 100 000 specimens of about 3500 morphologically defined species of adult moths, butterflies, tachinid flies, and parasitoid wasps Less than 1% of the species have such similar barcodes that a molecularly based taxonomic identification is impossible No specimen with a full barcode was misidentified when its barcode was compared with the barcode library Also as expected from early trials, barcoding a series from all morphologically defined species, and correlating the morphological, ecological and barcode traits, has revealed many hundreds of overlooked presumptive species Many but not all of these cryptic species can now be distinguished by subtle morphological and/or ecological traits previously ascribed to ‘variation’ or thought to be insignificant for species-level recognition Adding DNA barcoding to the inventory has substantially improved the quality and depth of the inventory, and greatly multiplied the number of situations requiring further taxonomic work for resolution

Similar estimates of temperature impacts on global wheat yield by three independent methods

Abstract: The potential impact of global temperature change on global crop yield has recently been assessed with different methods. Here we show that grid-based and point-based simulations and statistical regressions (from historic records), without deliberate adaptation or CO 2 fertilization effects, produce similar estimates of temperature impact on wheat yields at global and national scales. With a 1 °C global temperature increase, global wheat yield is projected to decline between 4.1% and 6.4%. Projected relative temperature impacts from different methods were similar for major wheat-producing countries China, India, USA and France, but less so for Russia. Point-based and grid-based simulations, and to some extent the statistical regressions, were consistent in projecting that warmer regions are likely to suffer more yield loss with increasing temperature than cooler regions. By forming a multi-method ensemble, it was possible to quantify 'method uncertainty' in addition to model uncertainty. This significantly improves confidence in estimates of climate impacts on global food security.

Abusive behavior in the workplace: a preliminary investigation.

Abstract: Dealing with hostile interpersonal relationships at work has been the topic of many popular books and workshops. Yet, with the exception of sexual harassment, there is surprisingly little mention in the organizational research literature on the nature, extent, and costs of abusive work interactions. These more frequent, more tolerated, and, thus, more damaging interpersonal interactions involve hostile verbal and nonverbal nonphysical behaviors directed by one or more persons towards another. The primary aim is to undermine the other to ensure compliance. In this study, we examined the extent to which students experienced nonsexual nonphysical abusive behavior on their jobs, the impact of this experience on job satisfaction, the characteristics of the actor and target, and responses to these behaviors, particularly turnover. The results indicate that although most of the students had very positive interactions at work, exposure to abusive behavior was familiar, was relatively frequent, and had a negative impact on the targets. The actors tended to be bosses and older than the targets. The quality of the interpersonal relationships at work was related to job satisfaction and intention to leave. The implications of these results are discussed with respect to individual, situational, and organizational factors that may be related to the presence and impact of abusive interpersonal interactions. Avenues for research on the nature, extent, and impact of these behaviors at both the individual and organizational levels are identified. Language: en