Over 40% of adults in the United States are considered obese. Obesity is known to cause abnormal metabolic effects and lead to other negative health consequences. Interestingly, differences in metabolism and contractile performance between obese and healthy weight individuals are associated with differences in skeletal muscle fiber type composition between these groups. Each fiber type is characterized by unique metabolic and contractile properties, which are largely determined by the myosin heavy chain isoform (MHC) or isoform combination that the fiber expresses. In previous studies, SDS-PAGE single fiber analysis has been utilized as a method to determine MHC isoform distribution and single fiber type distribution in skeletal muscle. Herein, a methodological approach to analyze MHC isoform and fiber type distribution in skeletal muscle was fine-tuned for use in human and rodent studies. In the future, this revised methodology will be implemented to evaluate the effects of obesity and exercise on the phenotypic fiber type composition of skeletal muscle.

In this project I explored the relationship between Qigong and Tai Chi Easy meditative practices and cardiometabolic risk factors, specifically looking at obesity and stress. The meditative focus of Qigong and Tai Chi Easy was expected to improve cardiac vagal tone which should lead to decreases in the inflammatory effects of stress. Additionally, due to the decreases in the harmful effects of stress, we expect to see a decrease in obesity through decreases in BMI and in waist circumference.

Obesity has reached epidemic proportions all around the world, and it has doubled in prevalence in both adults and children in over 70 countries from 1980 to 2015 (Afshin et al., 2017). Excessive weight gain in this proportion has been shown to negatively affect human cognition, reward neurocircuitry, stress responsiveness, and quality of life (Morris et al., 2015). Obesity is an example of a complex interaction between the environment (i.e., high-fat diets) and heredity (i.e., polygenic patterns of inheritance). The overconsumption of a high-fat diet (HFD) is an environmental factor that commonly induces weight gain (Hariri & Thibault, 2010). Two dietary-induced phenotypes have been observed in rats as a bimodal distribution of weight gain: obesity-prone (OP) and obesity-resistant (OR). Levin et al. (1997) investigated male and female HFD-fed Sprague-Dawley rats designated as OR when their weight gains were less than the heaviest chow-fed controls, and OP when their weight gains were greater than the heaviest chow-fed controls. OP rats showed greater weight gain, similar energy intake (EI), and similar feed efficiency (FE) compared to OR rats. Pagliassotti et al. (1997) designated male HFD-fed Wistar rats as OP and OR based on upper and lower tertiles of weight gain. OP rats displayed greater weight gain and EI than OR rats. These investigations highlight a predicament regarding rodent research in obesity: independent variables such as rat age, gender, strain, distribution of dietary macronutrients, and fatty acid composition of HFD and chow vary considerably, making it challenging to generalize data. Our experiment utilized outbred male Sprague-Dawley rats (5-6 weeks) administered a chow diet (19% energy from fat; 3.1 kcal/g) and a lard-based HFD (60% energy from fat; 5.24 kcal/g) over eight weeks. Separate rat populations were examined over three consecutive years (2017-2020), and independent obesogenic environmental variables were controlled. We investigated the persistence of weight gain, EI, and FE in HFD-fed rats inclusive of a population of designated OP and OR rats based on tertiles of weight gain. We define persistence as being p > 0.05. We hypothesize that the profiles (periodic data) of the dependent variables (weight gain, EI, FE) will be similar and persistent throughout the three separate years, but the magnitudes (cumulative data) of the dependent variables will differ. Our findings demonstrate that HFD, OP, and OR groups were persistent for periodic and cumulative weight gain, along with FE across the three consecutive independent years. Our findings also demonstrate impersistence for periodic EI in all groups, along with impersistence in cumulative EI for CHOW, OP, and OR groups. Therefore, our results allude to an inconsistent relationship between EI and weight gain, indicating that EI does not completely explain weight gain. Thus, the weakness between EI and weight gain relationship may be attributed to a polygenic pattern of inheritance, possibly signaling a weight setpoint regardless of EI.

Memory CD8+ T cells protect against secondary viral infections. They develop and maintain exclusively in circulation (e.g. central memory - Tcm) or are excluded from re-circulation (resident memory - Trm). The extracellular ATP receptor P2RX7 promotes both Tcm and Trm generation. High (P2RX7hi) P2RX7-expressing early effector cells show survival, memory and pluripotency genes. Conversely, many terminal effector (TE) and apoptosis genes are upregulated in low (P2RX7lo) P2RX7-expressing cells. Among these genes is the zinc-finger transcriptional repressor Zeb2, which promotes TE differentiation at the expense of the memory cell pool. Given that Zeb2 was higher in P2RX7lo early effector cells, we postulated that Zeb2 ablation would allow P2RX7-deficient CD8+ T cells to skew towards memory subsets. To test this, we used RNP-based CRISPR-Cas9 to knockout Zeb2 in wild type or P2RX7-deficient P14 cells. At the memory timepoint, Zeb2 ablation led to a rescue of the ability of P2RX7-deficient cells to differentiate into the CD62L+ Tcm and CD69hiCD103hi Trm subsets, as well as increase the population of each. Our data suggest that P2RX7 imprints a pro-memory signature that is, to some extent, dependent on the negative regulation of Zeb2.