Exploring the effects of a comprehensive Mediterranean diet verses a typical American diet on peripheral inflammation and the expression of inflammation-related genes in the dorsal hippocampus
Catherine Shoffner, Mary Skrabanek, Raleigh Robinson, Caleb Pryor, Morgan Bertrand, Vivienne Lacy, Paige Braden Kuhle, Gary Boehm, Michael Chumley
Approximately 72% of Americans are overweight or obese, partially due to the consumption of a Western diet (WD). The highly-processed WD is composed of simple carbohydrates, sugars, and saturated fats. The WD has been identified as a risk factor for Alzheimer’s disease (AD) due to the elevated levels of pro-inflammatory cytokines following long-term diet consumption. In contrast to the WD, the Mediterranean diet (MD) is a plant-based, mostly unsaturated fat diet. Research has shown that it is crucial to consume a balanced omega-6 to omega-3 ratio of 1:1 or 2:1, like that in the MD, as elevated ratios found in the WD lead to increased inflammation.
Previous studies generally utilize an extremely high-fat Western rodent diet that does not resemble that of the typical American. Thus, our lab designed two novel macronutrient-matched diets that mimic typical American or Mediterranean diets. In the current study, we examined the effects of the typical American diet (TAD) versus the MD in relation to pro-inflammatory cytokine production in serum and gene expression in the dorsal hippocampus of C57BL/6J mice. Following six months of TAD or MD consumption, the mice were treated with one intraperitoneal injection of lipopolysaccharide (LPS) or saline 4 hours prior to euthanasia. In comparison to the MD, mice consuming the TAD had increased expression and levels of pro-inflammatory cytokines in the dorsal hippocampus and serum, respectively.

In attempt to characterize the toxic effects of effluents discharged into surface waters, a previous study has shown crude oil contamination alters both mortality and hatching success among two model organisms: inland silversides and sheepshead minnows. Through toxicity testing it has become apparent that pollutants have the capacity to significantly alter growth and development of marine life. Specifically, it was found that exposure delayed the time of hatch or didn’t allow for hatch at all, and the unhatched embryos were less likely to survive. In addition, differences in both hatch and mortality were observed between the two organisms. Since the experimental conditions of the previous study were held constant for both groups the observed differences must be a result of a physiological difference, and a key distinction between the two species may lie in the differential use of the yolk sac. In the early stages of development marine organisms utilize the yolk sac as an internal source of energy prior to free feeding. It has been indicated that energy reserves and rate of depletions can differ between species. To determine the rate of yolk sac depletion in both inland silversides and sheepshead minnows, a total of 48 embryos per species were collected and raised to hatch. A subset of larvae at 24- to 96-hours post hatch were collected and the presence or absence of the yolk sac was determined. It was found that the yolk sac was depleted in 100% of the larvae 24-hours earlier for inland silversides as compared to sheepshead minnows. This observed difference shows a difference in the rates of energy reserve use and is indicative of a dissimilar response to external stressors, such as crude oil. These results may provide evidence of a mechanisms by which marine organisms experience differential hatch success and mortality when exposed to pollutants. Future research efforts might focus on the effect of yolk sac depletion as a key physiological distinction between species when outlining adverse effects of additional chemical exposures.

Oncorhynchus mykiss, commonly known as rainbow trout, exhibit partial migratory behavior, in which some individuals in a population will opt to migrate, whereas others do not. Consequently, there are two ecotypes of O. mykiss: the non-migratory rainbow trout (also known as residents) and the migratory steelhead (also known as migrants). Previous evidence generated from our lab demonstrated that various loci in the rainbow trout genome segregate between resident rainbow trout and migrant steelhead trout in the Sashin creek system of Alaska. A unique feature of the Sashin system is that a series of waterfalls separate the lake and stream, thereby inhibiting gene flow between the lake between migratory stream individuals and resident lake individuals. However, it is still unknown whether these same genetic markers also segregate between behaviors in other freshwater systems. Therefore, the goal of my research project is to use DMAS-qPCR to genotype known migrant individuals and known resident individuals from Little Sheep Creek, Oregon. This population is geographically separated from the Sashin Creek watershed and differs from Sashin in that both life histories can and do interbreed. From this project, I will be able to deduce 1) if genetic markers associated with life history development are shared across freshwater drainages and 2) to test if there is evidence of assortative mating (i.e., residents mating with residents and migrants mating with migrants) within the Little Sheep Creek system which would suggest genetic differences between life histories.

Mercury (Hg) is a global contaminant produced primarily by anthropogenic activities (i.e. coal-fired power plants, artisanal gold-mining operations) and is found in all freshwater systems. Primary producers (e.g., algae) and aquatic organisms that consume algae (e.g., emerging aquatic insects) are exposed to mercury through their diet. As adults, these emerging insects leave freshwater systems to reproduce, transferring both energy and Hg from their aquatic environment to the adjacent terrestrial environment. We assessed the emergence biomass of aquatic insects and insect–mediated Hg flux from 6 ponds in Northwest Greenland from July 1-30, 2022. Emergence biomass ranged from 0.09 to 176.91 mg/m2/day and insect-mediated Hg flux ranged from 0.009 ng/m2/day to 23.67 ng/m2/day across all ponds for the sampling period. This study suggests that small pongs in the High Arctic are important sources of both energy and contaminants to food webs in surrounding terrestrial ecosystems.

Alzheimer’s disease (AD) is ranked as the seventh leading cause of death in the US with over 6 million Americans currently diagnosed, and that number is projected to reach about 13 million by 2050. AD is currently believed to be caused by numerous factors ranging from genetics, lifestyle, and environmental conditions. The exact pathogenesis of AD remains uncertain, but the pathology of the disease includes the presence of amyloid beta (Aβ) plaques and neurofibrillary tangles composed of the protein tau in the brain. These are two proteins are normally found in the brains of healthy individuals, but amyloid-beta peptides are often degraded under normal conditions, while tau plays a role in stabilizing our cell’s cytoskeletal structures. In Alzheimer’s however, these proteins are misfolded and accumulate, causing disruptions in cell signaling and neuronal death, therefore worsening the disease. Aβ plaques also activate microglial cells, which produce cytokines and induce inflammation. Cytokines are signaling molecules produced by immune cells that mediate inflammatory signaling. Activation of an inflammasome complex found in microglial cells, NLRP3, leads to the production of the cytokine IL-1β which has been implicated in Alzheimer’s due to its ability to induce and maintain this chronic cycle of inflammation, and possibly results in more amyloid-beta deposition. Our research looks into the mode of action of novel anti-inflammatory drugs and their potential to reduce inflammation at the level of the NLRP3 inflammasome as a mechanism to slow down the progression of AD.