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 & Poison control. The organization has 26542 authors who have published 50553 publications receiving 1715255 citations. The organization is also known as: U of G & Guelph University.

A Possible Essential Role for Dietary Linolenic Acid in the Development of the Young Rat

Abstract: Female rats were fed semi-purified diets containing 10% safflower oil or 10% soybean oil for six weeks prior to mating and through-out pregnancy and lactation. The progeny were weaned to the diet of the dam. Physical, neuromotor and reflex development was monitored in the progeny prior to weaning and learning ability of the mature progeny was assessed in a simple Y-maze test. Brain lipid analyses were conducted in the progeny at birth, 21 and 210 days of age. Inclusion of soybean oil in the diet resulted in higher levels of 22:6omega3 and lower levels of 22:5omega6 in the brain ethanolamine glycerophosphatides. The nature of the dietary fat exerted no effect on the physical development, onset of reflexologic responses or onset of neuromotor co-ordination in the pups. The soybean oil-fed animals spent more time in certain neuromotor activities possibly associated with explorative drive than did their safflower oil-fed counterparts. The performance of the mature soybean oil-fed progeny in the discrimination-learning test was superior to that of progeny fed safflower oil. The association of superior learning capacity with dietary soybean oil-induced incorporation of omega3 fatty acids into the brain glycerophosphatides is offered as support for an essential role for dietary linolenic acid for the young rat.

Na+/K+-ATPase alpha-isoform switching in gills of rainbow trout (Oncorhynchus mykiss) during salinity transfer.

Abstract: We identified five Na+/K+-ATPase alpha-isoforms in rainbow trout and characterized their expression pattern in gills following seawater transfer. Three of these isoforms were closely related to other vertebrate alpha1 isoforms (designated alpha1a, alpha1b and alpha1c), one isoform was closely related to alpha2 isoforms (designated alpha2) and the fifth was closely related to alpha3 isoforms (designated alpha3). Na+/K+-ATPase alpha1c- and alpha3-isoforms were present in all tissues examined, while all others had tissue specific distributions. Four Na+/K+-ATPase alpha-isoforms were expressed in trout gills (alpha1a, alpha1b, alpha1c and alpha3). Na+/K+-ATPase alpha1c- and alpha3-isoforms were expressed at low levels in freshwater trout gills and their expression pattern did not change following transfer to 40% or 80% seawater. Na+/K+-ATPase alpha1a and alpha1b were differentially expressed following seawater transfer. Transfer from freshwater to 40% and 80% seawater decreased gill Na+/K+-ATPase alpha1a mRNA, while transfer from freshwater to 80% seawater caused a transient increase in Na+/K+-ATPase alpha1b mRNA. These changes in isoform distribution were accompanied by an increase in gill Na+/K+-ATPase enzyme activity by 10 days after transfer to 80% seawater, though no significant change occurred following transfer to 40% seawater. Isoform switching in trout gills following salinity transfer suggests that the Na+/K+-ATPase alpha1a- and alpha1b-isoforms play different roles in freshwater and seawater acclimation, and that assays of Na+/K+-ATPase enzyme activity may not provide a complete picture of the role of this protein in seawater transfer.

Circumpolar distribution and carbon storage of thermokarst landscapes

Abstract: Thermokarst is the process whereby the thawing of ice-rich permafrost ground causes land subsidence, resulting in development of distinctive landforms. Accelerated thermokarst due to climate change will damage infrastructure, but also impact hydrology, ecology and biogeochemistry. Here, we present a circumpolar assessment of the distribution of thermokarst landscapes, defined as landscapes comprised of current thermokarst landforms and areas susceptible to future thermokarst development. At 3.6 × 106 km2, thermokarst landscapes are estimated to cover ∼20% of the northern permafrost region, with approximately equal contributions from three landscape types where characteristic wetland, lake and hillslope thermokarst landforms occur. We estimate that approximately half of the below-ground organic carbon within the study region is stored in thermokarst landscapes. Our results highlight the importance of explicitly considering thermokarst when assessing impacts of climate change, including future landscape greenhouse gas emissions, and provide a means for assessing such impacts at the circumpolar scale.