No description available.

No description available.

Acetyl-CoA carboxylase (ACC) catalyzes the formation of malnoyl-CoA, which in turn controls the rate of fatty acid metabolism. ACC beta or 2 has been shown to be localized on the mitochondria in close proximity to carnintine palmitoyl transferase 1 (CPT-1), the enzyme responsible for the influx of acyl-CoA into the matrix where beta oxidation takes place. CPT-1 is inhibited by malonyl-CoA produced by ACC. It has been well documented that AMP activated kinase (AMPK) when activated phosphorylates and inactivates ACC. ACC is controlled allosterically by citrate, which activates, and by palmitoyl-COA, which inhibits. In this study, we asked the question, "Does phosphorylation by AMPK effect the inhibition of ACC by palmitoyl-CoA?" ACC was isolated and then subjected to phosphorylation and activity was measured in varying concentrations of acetyl-CoA and citrate. Phosphoryation reduced the substrate (acetyl-CoA) saturation activity curves for ACC at all levels of palmitoyl-CoA. The Ki for palmitoyl-CoA inhibition of ACC was reduced from 1.7 ± 0.25 µM to 0.85 ± 0.13 uM (p<0.05) as a consequence of phosphorylation. In addition the citrate activation curves for ACC were greatly reduced in the presence of palmitoyl-CoA. The data show that skeletal muscle ACC or ACC-beta is more potently inhibited by palmitoyl-CoA after phosphorylation by AMPK. During long-term exercise when AMPK is activated and muscle palmitoyl-CoA is elevated this may contribute to the low malonyl-CoA and increased fatty acid oxidation.

Plants synthesize and store oil mostly as triacylglycerols (TAG) in seeds that is transcriptionally controlled by WRINKLED 1 (WRI1), an APETALA2 (AP2) transcription factor. In contrast, avocado (Persea americana) mesocarp, which accumulates ~70% lipids by dry weight showed high expression of WRI2, along with WRI1 and WRI3. Among the four Arabidopsis WRI paralogs, WRI2 is nonfunctional, while the others are expressed in a tissue-specific manner. Through in silico analysis, we identified that PaWRI2 has a single intact AP2 DNA-binding domain and lacks a C-terminal intrinsically disordered region (IDR3) and PEST motif, which likely results in a relatively stable protein, compared to its Arabidopsis ortholog. We further demonstrated that avocado WRI2 is functional, unlike Arabidopsis WRI2, and accumulates TAG when transiently expressed in Nicotiana benthamiana leaves. Additionally, co-infiltration of PaWRI2 with PaWRI1 and genes encoding for terminal step in TAG assembly, acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) and/or phospholipid:diacylglycerol acyltransferase 1 (PDAT1) also led to further increase in the lipid content and oleic acid levels in ‘benth’ leaves. Quantitative real-time PCR (qPCR) analyses of > 40 fatty acid biosynthetic pathway genes revealed that several were distinctly up or down regulated by the expression of PaWRI2 and PaWRI1. In conclusion, avocado WRI2 is capable of transactivation of fatty acid biosynthesis genes and TAG accumulation, synergistically with DGAT1 and PDAT1, in nonseed tissues. This study provides a functional role for WRI2 in a basal angiosperm species that is likely lost in modern angiosperms and thus provides basis for mechanistic differences in the transcriptional regulation of lipid biosynthesis among different plant species and between seed and nonseed tissues.

In many higher plants, seed oil accumulation is governed by complex multilevel regulatory networks including transcriptional regulation, which primarily affects fatty acid biosynthesis. Tree peony (), a perennial deciduous shrub endemic to China is notable for its seed oil that is abundant in unsaturated fatty acids. We discovered that a tree peony trihelix transcription factor, PrASIL1, localized in the nucleus, is expressed predominantly in developing seeds during maturation. Ectopic overexpression of in leaf tissue and seeds significantly reduced total fatty acids and altered the fatty acid composition. These changes were in turn associated with the decreased expression of multitudinous genes involved in plastidial fatty acid synthesis and oil accumulation. Thus, we inferred that PrASIL1 is a critical transcription factor that represses oil accumulation by down-regulating numerous key genes during seed oil biosynthesis. In contrary, up-regulation of oil biosynthesis genes and a significant increase in total lipids and several major fatty acids were observed in silenced tree peony leaves. Together, these results provide insights into the role of trihelix transcription factor PrASIL1 in controlling seed oil accumulation. can be targeted potentially for oil enhancement in tree peony and other crops through gene manipulation.

[This corrects the article DOI: 10.3389/fpls.2021.796181.].

No description available.

The Trinity River is an urbanized, effluent-dominated river, and is heavily relied upon for drinking water. The benthic macroinvertebrate community has been monitored for over 20 years, with the focus of this dissertation on three studies (1987-88, 2005, and 2011). Water quality improvement following dechlorination resulted in increased benthic metrics. Overall habitat quality, in-stream cover, surface water total organic carbon, sediment total organic carbon, near-field urban land-use, near-field forested land-use, surface water surfactant toxic units, and depositional sediment biofilm fatty acids all have statistically significant relationships with benthic macroinvertebrate metrics. These relationships are better defined with increased taxonomic resolution at the genus/species level for all benthic taxa, including Chironomidae and Oligochaeta. It is recommend that benthic identifications for state and city water quality assessments be done at the genus/species level. A novel method for quantifying depositional sediment biofilm fatty acids has been produced and tested in this dissertation. Benthic metrics are directly related to fatty acid profiles, with several essential fatty acids found only at upstream sites.

Bisphenols are used in the process of polymerization of polycarbonate plastics and epoxy resins. Bisphenols can easily migrate out of plastic products and enter the gastrointestinal system. By increasing colonic inflammation in mice, disrupting the intestinal bacterial community structure and altering the microbial membrane transport system in zebrafish, bisphenols seem to interfere with the gut microbiome. The highly abundant human commensal bacterium Bacteroides thetaiotaomicron was exposed to bisphenols (Bisphenol A (BPA), Bisphenol F (BPF), Bisphenol S (BPS)), to examine the mode of action, in particular of BPF. All chemicals caused a concentration-dependent growth inhibition and the half-maximal effective concentration (EC50) corresponded to their individual logP values, a measure of their hydrophobicity. B. thetaiotaomicron exposed to BPF decreased membrane fluidity with increasing BPF concentrations. Physiological changes including an increase of acetate concentrations were observed. On the proteome level, a higher abundance of several ATP synthase subunits and multidrug efflux pumps suggested an increased energy demand for adaptive mechanisms after BPF exposure. Defense mechanisms were also implicated by a pathway analysis that identified a higher abundance of members of resistance pathways/strategies to cope with xenobiotics (i.e., antibiotics). Here, we present further insights into the mode of action of bisphenols in a human commensal gut bacterium regarding growth inhibition, and the physiological and functional state of the cell. These results, combined with microbiota-directed effects, could lead to a better understanding of host health disturbances and disease development based on xenobiotic uptake.

Ruminant livestock play a vital role in fulfilling the nutrient requirements of humans by providing protein, energy, and essential microminerals. With the increasing demand for meat and dairy products, the ruminant industry must continue to improve the productivity and efficiency of ruminant animals with limited resources while minimizing the environmental impact. Rumen fermentation is the focal point of the productivity and efficiency of the animal and numerous chemical, physical and biochemical interactions make the rumen a complex ecosystem. Therefore, improving the understanding of fermentation dynamics in a holistic manner and characterizing how fermentation varies in response to different nutrient supplies can greatly expand our knowledge on rumen fermentation to develop better engineered rumen manipulation strategies. The central aim of these investigations was to employ alternative analytical strategies for holistic exploration of complex relationships among rumen, animal, and dietary variables and to estimate rumen volatile fatty acid (VFA) dynamics under different nutrient supplies. The objective of the first study was to explore the strengths and limitations of mixed-model meta-analysis, recursive feature elimination (RFE), and additive Bayesian networking (ABN) in identifying relationships among diet, rumen, and milk performance variables. Both mixed-models and ABN agreed upon most of the variables and relationships identified while RFE failed to capture interactions. Given the capacity of mixed models for quantitative inquiry and the potential of ABN to illustrate complex associations in a more intuitive way, future investigations combining both approaches hold potential to explore intercorrelated data in a holistic manner. Followed by the successful use of ABN in the first study, the goal of a follow up study was to investigate the potential of two different network approaches to explore rumen level interactions using data generated in continuous culture experiments. Two network analysis approaches, EBIC-LASSO network (ELN) and Bayesian learning network (BLN) were leveraged to explore the relationships among rumen fermentation parameters in continuous culture experiments. Unidirectional ELN illustrated prominent variables while BLN, which produces a directed acyclic graph, identified directional relationships implying causality. Overall, both networking approaches demonstrate strengths in capturing connectedness and directionality of rumen fermentation variables. In a complementary line of work, the next experiment focused on developing an alternative method for iso-tope based assessments to produce less expensive, and more efficient screening of fermentation conditions driven by diet. Cannulated wethers were used in this study and 4 dietary treatments combining lowly and highly degradable fiber (timothy hay and beet pulp, respectively) and protein (heat-treated soybean meal and soybean meal, respectively) were tested. Results indicated that fluid volume of the rumen and the rate of passage were influenced by protein, but not fiber, source. Higher rumen volumes and lower passage rates were associated with heat-treated soybean meals. The effect of dietary treatments on VFA absorption dynamics was prominent compared to the minimal changes in production dynamics. Overall, heat-treated soybean meal appears to influence VFA disappearance resulting in low concentrations within the rumen, but greater flux of VFA disappearance. In conclusion, this method demonstrated the capacity to estimate VFA dynamics beyond concentrations and molar proportions while being cost effective and more physiologically relevant. In a fourth study, we sought to investigate the growth performance and rumen VFA profile in response to different planes of nutrients and naturally occurring coccidiosis. Coccidiosis infection altered rumen isobutyrate concentrations and tended to alter major VFA concentrations suggesting the need of future work to explore coccidiosis effects on rumen fermentation. The first two investigations highlighted the potential and strength of leveraging alternative analytical tools to complement statistical approaches generally used in ruminant nutrition while concurrently improving ability to explain complex associations in the rumen. The third and fourth projects characterized the rumen VFA dynamics and profile in response to the different nutrient degradability and health status, respectively. Collectively, these investigations contribute to better understanding of rumen dynamics through novel analytical and experimental approaches. / Doctor of Philosophy / With increasing global population, income, urbanization, and changes in dietary habits, the demand for meat and milk continues to grow. The ruminant animal industries (beef cattle, dairy cattle, sheep, goat, and buffalo) carry the burden of increasing production utilizing limited resources while minimizing the negative environmental impact caused by ruminant operations. To achieve this goal the productivity of the animal must be increased, and in order to increase the efficiency of production a better understanding of factors driving the production is critical. Ruminant animals have the unique ability to convert plant fiber into human edible milk and meat through a process that predominantly occurs in the special gut compartment called the rumen. In this process several compounds are produced, and among those volatile fatty acid (VFA) is of utmost importance because it fulfills energy demands for growth, production and reproduction. The rumen is a complex ecosystem consisting of numerous variables and associations. Understanding those relationships is crucial to manipulate rumen mechanisms. The overall objective of this work was to evaluate the potential of alternative statistical approaches, which demonstrated success in other disciplines, for better depiction of complex associations and characterization of production and absorption mechanisms of rumen VFA in response to different nutrient supplies. The objective of first investigation was to evaluate a feature selection method (recursive feature elimination; RFE) and a network approach (Additive Bayesian network; ABN) concurrently with a standard variable selection method (mixed model meta-analysis) commonly used to develop animal nutrition models. We attempted to find out the most important dietary, rumen, and animal variables for milk yield, milk fat and protein content as an example. Results indicate that the network approach was well aligned with the standard tool and can be used as a complementary approach. In our second investigation, we leveraged two networking analyses, a frequentist network which was unidirectional and a Bayesian network which was directional to explore rumen level interactions. The unidirectional network approach highlighted the most important variables in the rumen and numerous relationships among these variables. The directional network was more useful in understanding of causal associations within the system. In the third experiment we estimated the production and absorption of VFA in response to the different protein (heat-treated and regular soybean meal) and fiber (timothy hay and beet pulp) sources. The results revealed that the production of VFA was minimally affected by the diet, but the absorption was higher with heat-treated soybean meal. Our last project investigated the effect of parasitic infection, i.e., coccidiosis, and high and low levels of nutrition on growth and rumen VFA of growing lambs. Infection of coccidiosis altered a minor VFA (isobutyrate) and tended to alter total and major VFA (acetate and propionate). All these findings help to improve our understanding of rumen fermentation and subsequently develop strategies to manipulate rumen fermentation to enhance efficiency and productivity.