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.

Infectious Disease Outbreaks Related to Drinking Water in Canada, 1974–2001

Abstract: Introduction : Les eclosions recentes d'infections d'origine hydrique a Walkerton et a North Battleford ont galvanise l'attention publique sur la qualite des reserves d'eau potable. Nous avons analyse des renseignements sur les eclosions d'origine hydrique ayant eu lieu au Canada entre 1974 et 2001 afin de degager des tendances, de reexaminer le niveau de declaration et d'accroitre notre comprehension de l'impact de la qualite de l'eau potable sur le fardeau des maladies d'origine hydrique a l'echelle nationale. Methode : Nous avons rassemble des donnees d'enquetes sur des eclosions d'origine hydrique a partir de sources publiees et non publiees recueillies aupres de professionnels de la sante publique au Canada. Nous avons categorise les donnees selon le type de service d'eau potable (public ou non). En tenant compte de la valeur probante des donnees disponibles, nous avons aussi categorise les eclosions selon notre certitude d'une origine hydrique (possible, probable ou certaine). Resultats : En tout, 288 eclosions de maladies ont ete reliees a une source d'eau potable. Il y a eu 99 eclosions associees aux systemes publics d'eau, 138 aux systemes parapublics, et 51 aux systemes prives. Les causes infectieuses connues (en ordre de frequence) etaient Giardia, Csmpylobacter, Cryptosporidium, les norovirus, Salmonella et le virus de l'hepatite A. Discussion : Nous avons constate que les conditions meteorologiques, la proximite de populations animales, le mauvais fonctionnement du systeme de traitement et les carences dans les pratiques de traitement ou d'entretien etaient associes aux eclosions provenant de reserves d'eau potable. Notre recherche souleve plusieurs questions rattachees a l'exactitude, a la comparabilite, au niveau de detail et a la coordination des donnees. Un systeme de surveillance national, systematique et coordonne permettrait de mieux degager des tendances et d'effectuer des comparaisons d'une province ou d'un territoire a l'autre, et appuierait l'elaboration d'interventions visant a alleger le fardeau des maladies d'origine hydrique.

The role of triploid hybrids in the evolutionary dynamics of mixed-ploidy populations

Abstract: Theory suggests that the evolution of autotetraploids within diploid populations will be opposed by a minority-cytotype mating disadvantage. The role of triploids in promoting autotetraploid establishment is rarely considered, yet triploids are often found in natural populations and are formed in experimental crosses. Here, I evaluate the effects of triploids on autotetraploid evolution using computer simulations and by synthesizing research on the evolutionary dynamics of mixed-ploidy populations in Chamerion angustifolium (Onagraceae). Simulations show that the fate of a tetraploid in a diploid population varies qualitatively depending on the relative fitness of triploids, the ploidy of their gametes and the fitness of diploids relative to tetraploids. In general, even partially fit triploids can increase the likelihood of diploid-tetraploid coexistence and, in some cases, facilitate tetraploid fixation. Within the diploid-tetraploid contact zone of C. angustifolium, mixed populations are common (43%), and often (39%) contain triploids. Greenhouse and field studies indicate that triploid fitness is low (9% of diploids) but variable. Furthermore, euploid gametes produced by triploids can be x, 2x or 3x and contribute the majority (62%) of new polyploids formed in each generation (2.3 x 10 -3 ). Although triploid bridge, alone, may not account for the evolution of autotetraploidy in C. angustifolium, it probably contributes to the prevalence of mixed-ploidy populations in this species. Therefore, in contrast to hybrids in homoploid species, triploids may actually facilitate rather than diminish the fixation of tetraploids by enhancing the rate of formation.

Omega-3 fatty acids and neuropsychiatric disorders.

Abstract: Epidemiological evidence suggests that dietary consumption of the long chain omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), commonly found in fish or fish oil, may modify the risk for certain neuropsychiatric disorders As evidence, decreased blood levels of omega-3 fatty acids have been associated with several neuropsychiatric conditions, including Attention Deficit (Hyperactivity) Disorder, Alzheimer's Disease, Schizophrenia and Depression Supplementation studies, using individual or combination omega-3 fatty acids, suggest the possibility for decreased symptoms associated with some of these conditions Thus far, however, the benefits of supplementation, in terms of decreasing disease risk and/or aiding in symptom management, are not clear and more research is needed The reasons for blood fatty acid alterations in these disorders are not known, nor are the potential mechanisms by which omega-3 fatty acids may function in normal neuronal activity and neuropsychiatric disease prevention and/or treatment It is clear, however, that DHA is the predominant n-3 fatty acid found in the brain and that EPA plays an important role as an anti-inflammatory precursor Both DHA and EPA can be linked with many aspects of neural function, including neurotransmission, membrane fluidity, ion channel and enzyme regulation and gene expression This review summarizes the knowledge in terms of dietary omega-3 fatty acid intake and metabolism, as well as evidence pointing to potential mechanisms of omega-3 fatty acids in normal brain functioning, development of neuropsychiatric disorders and efficacy of omega-3 fatty acid supplementation in terms of symptom management

Time-resolved luminescence and photoconductivity of polycrystalline ZnO films

Abstract: The relative intensities of the green and blue luminescence of a ZnO film was shown to depend on the excitation regime. Time-resolved and steady-state luminescence were studied along with photoconductivity transients. Under continuous excitation the film emitted green light, while under pulsed excitation the luminescence was either blue or green, depending on the intensity of the excitation pulse. The intensity of the blue component depended linearly on the pulse intensity while the green intensity followed a sublinear power law dependence with the exponent α=1/3. The transient luminescence exhibited fast (below nanosecond) and slow (microsecond) decay components at room temperature. The fast component was ascribed to interband exciton recombination, and the slow component was attributed to an electron-hole recombination involving a donor-acceptor complex, which most likely consisted of oxygen and zinc vacancies. In this model, the complex can emit light only when it is activated, i.e., oxygen vacancy is ...

LeProT1, a Transporter for Proline, Glycine Betaine, and γ-Amino Butyric Acid in Tomato Pollen

Abstract: During maturation, pollen undergoes a period of dehydration accompanied by the accumulation of compatible solutes.Solute import across the pollen plasma membrane, which occurs via proteinaceous transporters, is required to support pollen development and also for subsequent germination and pollen tube growth. Analysis of the free amino acid composition of various tissues in tomato revealed that the proline content in flowers was 60 times higher than in any other organ analyzed. Within the floral organs, proline was confined predominantly to pollen, where it represented >70% of total free amino acids. Uptake experiments demonstrated that mature as well as germinated pollen rapidly take up proline. To identify proline transporters in tomato pollen, we isolated genes homologous to Arabidopsis proline transporters. LeProT1 was specifically expressed both in mature and germinating pollen, as demonstrated by RNA in situ hybridization. Expression in a yeast mutant demonstrated that LeProT1 transports proline and γ-amino butyric acid with low affinity and glycine betaine with high affinity. Direct uptake and competition studies demonstrate that LeProT1 constitutes a general transporter for compatible solutes.