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Articles 1 - 6 of 6
Full-Text Articles in Life Sciences
Severe Hypoxia Up-Regulates Gluconeogenesis In Daphnia, Morad C. Malek
Severe Hypoxia Up-Regulates Gluconeogenesis In Daphnia, Morad C. Malek
Undergraduate Honors Theses
Hypoxia is a significant low oxygen state that has complex and diverse impacts on organisms. In aerobes, various adaptive responses to hypoxia are observed that vary depending on the level of oxygen depletion and previous adaptation, hence the continued attention to hypoxia as an important abiotic stressor. Adaptive responses to hypoxia are primarily governed by the hypoxia-inducible factors (HIFs), which activate downstream genetic pathways responsible for oxygen transport and metabolic plasticity. In aquatic habitats, oxygen availability can vary greatly over time and space. Therefore, aquatic organisms’ adaptation to hypoxia is likely pervasive, especially in genotypes originating from waterbodies prone to …
Effects Of Maternal And Neonatal Hypoxia On The Future Life History Of Daphnia Magna, Rachael Lowman
Effects Of Maternal And Neonatal Hypoxia On The Future Life History Of Daphnia Magna, Rachael Lowman
Undergraduate Honors Theses
Early exposure to hypoxia is related to a variety of physiological and metabolic changes that have lasting effects on organisms’ physiology and life history. We measured the effects of maternal and embryonic mild, intermittent hypoxia on the life history of four clones of microcrustacean Daphnia magna, an emerging model organism for the studies of senescence and longevity. Daphnia individuals were produced parthenogenically, maintained in individual vials, and fed standard algal concentration daily. The cohort consisted of 189 individuals. We measured body size at first reproduction, fecundity (including late-life fecundity peak), offspring sex ratio, and longevity. We found no effect …
Does Thermotolerance In Daphnia Depend On The Mitochondrial Function?, Rajib Hasan
Does Thermotolerance In Daphnia Depend On The Mitochondrial Function?, Rajib Hasan
Electronic Theses and Dissertations
Thermotolerance limit in aquatic organism is set by the ability to sustain aerobic scope to sudden temperature shifts. This study tested the genetic and plastic differences in thermotolerance of Daphnia that can be explained by the differences in the ability to retain mitochondrial integrity at high temperatures. Five genotypes with different biogeographic origins were acclimated to 18ᵒC and 25ᵒC. We developed a rhodamine 123 in-vivo assay to measure mitochondrial membrane potential and observed higher fluorescent in heat damaged tissues as the disruption of the mitochondrial membrane potential. Significant effects on temperature tolerance were observed with CCCP …
Escaping The Arrhenius Tyranny: Metabolic Compensation During Exposure To High Temperature In Daphnia, Bret L. Coggins
Escaping The Arrhenius Tyranny: Metabolic Compensation During Exposure To High Temperature In Daphnia, Bret L. Coggins
Electronic Theses and Dissertations
Poikilothermic organisms experience trade-offs by differential physiological demands generated by temperature extremes. Many such organisms exhibit acclimatory effects, adjusting their metabolism and physiology to recently experienced temperatures. One such acclimatory effect is metabolic compensation, the deceleration of biological rates below Arrhenius expectations. Daphnia magna is eurythermal, and if acclimated to mildly stressful temperatures first, survives longer in lethal temperatures. This study examined the effect of ambient temperature (5°C-37°C) and acclimation history (lifetime at 10°C or 25°C) on the oxygen consumption rates of 8 genotypes of Daphnia with high or low acute temperature tolerance. There were decelerations of respiratory rates across …
Genetic Variation In Long-Term And Short-Term Physiological Changes In Daphnia Magna During Acclimation To High Temperature, Bret L. Coggins
Genetic Variation In Long-Term And Short-Term Physiological Changes In Daphnia Magna During Acclimation To High Temperature, Bret L. Coggins
Undergraduate Honors Theses
The aquatic zooplankton crustacean Daphnia magna must be able to tolerate thermal stress in order to survive their native shallow ponds that are susceptible to drastic seasonal and diurnal temperature fluctuations as well as to globally increasing temperatures. Survival in such variable environments requires plastic responses that must include fundamental aspects of Daphnia biochemistry and physiology. Adaptive response to selection favoring such plastic phenotypes requires the presence of genetic variation for plastic response in natural populations. Adverse effects of elevated temperature on aquatic organisms are diverse and so are their plastic responses; among the most severe challenges aquatic organisms face …
An Evaluation Of Coating Material Dependent Toxicity Of Silver Nanoparticles, Thilini Upekshika Silva
An Evaluation Of Coating Material Dependent Toxicity Of Silver Nanoparticles, Thilini Upekshika Silva
Electronic Theses and Dissertations
Silver nanoparticles (AgNPs) synthesized using numerous types of coating materials may exhibit different toxicity effects. The study evaluated coating material dependent toxicity by selecting 3 types of AgNP synthesis methods with different coating materials (citrate, polyvinyl pyrrolidone, and branched polyethyleneimine, coated AgNPs as citrate-AgNPs, PVP-AgNPs, and BPEI-AgNPs respectively). Two acute aquatic toxicity tests were performed; 48hr D. magna and MetPLATE E. coli toxicity tests. Significantly different toxicity effects were observed in D. magna test exhibiting lethal median concentrations (LC50) for citrate-AgNPs, PVP-AgNPs, and BPEI AgNPs respectively as, 2.7, 11.2, and 0.57μg/L. Median inhibitory concentrations (EC50) for MetPLATE tests were 1.27, …