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.

Effects of Atrazine on Fish, Amphibians, and Aquatic Reptiles: A Critical Review

Abstract: The herbicide atrazine is widely used in agriculture for the production of corn and other crops. Because of its physical and chemical properties, atrazine is found in small concentrations in surface waters—habitats for some species. A number of reports on the effects of atrazine on aquatic vertebrates, mostly amphibians, have been published, yet there is inconsistency in the effects reported, and inconsistency between studies in different laboratories. We have brought the results and conclusions of all of the relevant laboratory and field studies together in this critical review and assessed causality using procedures for the identification of causative agents of disease and ecoepidemiology derived from Koch’s postulates and the Bradford‐Hill guidelines. Based on a weight of evidence analysis of all of the data, the central theory that environmentally relevant concentrations of atrazine affect reproduction and/or reproductive development in fish, amphibians, and reptiles is not supported by the vast majority of observations. The same conclusions also hold for the supporting theories such as induction of aromatase, the enzyme that converts testosterone to estradiol. For other responses, such as immune function, stress endocrinology, parasitism, or population-level effects, there are no indications of effects or there is such a paucity of good data that definitive conclusions cannot be made.

The quantitative and molecular genetic architecture of a subdivided species

Abstract: In an effort to elucidate the evolutionary mechanisms that determine the genetic architecture of a species, we have analyzed 17 populations of the microcrustacean Daphnia pulex for levels of genetic variation at the level of life-history characters and molecular markers in the nuclear and mitochondrial genomes. This species is highly subdivided, with approximately 30% of the variation for nuclear molecular markers and 50% of the variation for mitochondrial markers being distributed among populations. The average level of genetic subdivision for quantitative traits is essentially the same as that for nuclear markers, which superficially suggests that the life-history characters are diverging at the neutral rate. However, the existence of a strong correlation between the levels of population subdivision and broadsense heritabilities of individual traits argues against this interpretation, suggesting instead that the among-population divergence of some quantitative traits (most notably body size) is being driven by local adaptation to different environments. The fact that the mean phenotypes of the individual populations are also strongly correlated with local levels of homozygosity indicates that variation in local inbreeding plays a role in population differentiation. Rather than being a passive consequence of local founder effects, levels of homozygosity may be selected for directly for their effects on the phenotype (adaptive inbreeding depression). There is no relationship between the levels of variation within populations for molecular markers and quantitative characters, and this is explained by the fact that the average standing genetic variation for life-history characters in this species is equivalent to only 33 generations of variation generated by mutation.

A simple colorimetric assay for muramic acid and lactic acid

Abstract: The Barker and Summerson method of assaying lactic acid colorimetrically is modified to provide a simple and fast method of measuring lactic acid and other compounds such as muramic acid and glyceraldehyde that will release acetaldehyde on incubation in hot sulfuric acid. The assay can be done with open tubes and no more complicated equipment than a spectrophotometer. A further modification allows a relatively specific determination of formaldehyde.

Mechanisms and Regulation of Protein-Mediated Cellular Fatty Acid Uptake: Molecular, Biochemical, and Physiological Evidence

Abstract: ![Figure][1] Arend Bonen Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada abonen{at}uoguelph.ca ![Figure][1] Adrian Chabowski Department of Physiology, Medical University of Bialystok, Bialystok, Poland ![