Browsing by Author "Lapointe, Michel R."

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The effects of dietary ingestion of nickel recovery slag as a grit source on avian bone
(2020-06-05) Lapointe, Michel R.
Nickel recovery slag has been ubiquitously deposited in the environment of the Sudbury, Ontario basin giving merit to a study of the impact of this foreign material on wildlife in the area. In this work, the effects of ingestion of this largely metallic grit source on the bone health of Columbia Livia Domestica pigeons was measured. This was accomplished by controlling the diets of two groups of birds, one given exclusively limestone grit, the second given exclusively slag as a grit source. After one year of this controlled diet, the subjects were euthanized and their tibiotarsi were subsequently harvested for testing. Tests performed on the tibiotarsi including breaking strength, Young’s modulus, cortical thickness, density, bone mineral density, and mass spectrometry with a focus on iron and calcium concentrations. Additionally, conventional micrographs and scanning electron micrographs with accompanying energy dispersive spectrometry were collected. Our analyses of the results are consistent with degraded bone physiology in the slag‐fed group compared to the control birds.
On the radiobiology of anhydrobiotic saccharomyces cerevisiae : unraveling the role of intracellular water in the radiation response
(2024-03-26) Lapointe, Michel R.
Anhydrobiosis, denoting “Life without water” in Greek, is an adaptative characteristic held by few eukaryotic organisms. Given the integral role that intracellular water plays in the mechanisms of low linear energy transfer (LET) radiation-induced DNA damage, the question is raised as to what effect the absence of water may have on the radiation resistance of anhydrobiotic organisms. This project utilized anhydrobiotic Saccharomyces cerevisiae, which is a budding yeast and the same organism used in the fermentation of beer, wine, and bread. This yeast is extremely well studied. It has a radiation response on the genetic level, which is very similar to human cells. With its eukaryotic cell structure, numerous human gene homologs and paralleled molecular processes in the repair of ionizing radiation-induced DNA damage, it is regarded as an excellent biological model to study the foundational biological effects of radiation exposure. Furthermore, its anhydrobiotic capabilities make it an extremely low-maintenance model, excellent for running long-term experiments where laboratory access is acutely challenging. As such, its utility in the study of sub-natural background radiation (NBR) exposure has been investigated. Overall, the goal of this work was to decipher how anhydrobiosis influences radiation resistance, with a particular focus on the implications for sub-natural background radiation exposure. This work has shown that the radiation tolerance induced by desiccation is remarkably consistent through a wide range of radiation doses. Significant metabolic perturbations relating to sub-NBR exposure and potassium-isotope availability were observed. Anhydrobiosis perturbed the radiation response of S. cerevisiae in a predictable manner with low-LET radiation, and further investigation into the metabolic effects of sub-NBR radiation exposure is prudent to better understand the role of NBR in normal biological function and homeostasis.