The effects of R(+)-lipoic acid supplementation on regulation of human skeletal muscle pyruvate dehydrogenase

This thesis investigated whole body glucose disposal and the adaptive changes in skeletal muscle carbohydrate metabolism following 28 d of supplementation with 1000 mg R(+)-lipoic acid in young sedentary males (age, 22.1 ± 0.67 yr, body mass, 78.7 ± 10.3 kg, n=9). In certain individuals, lipoic acid decreased the 180-min area under the glucose concentration and insulin concentration curve during an oral glucose tolerance test (OGTT) (n=4). In the same individuals, lipoic acid supplementation decreased pyruvate dehydrogenase kinase activity (PDK) (0.09 ± 0.024 min"^ vs. 0.137 ± 0.023 min'\ n=4). The fasting levels of the activated form of pyruvate dehydrogenase (PDHa) were decreased following lipoic acid (0.42 ± 0.13 mmol-min'kg'^ vs. 0.82 ± 0.32 mmolrnin'^kg"\ n=4), yet increased to a greater extent during the OGTT (1.21 ± 0.34 mmol-min'kg"' vs. 0.81 ±0.13 mmolmin"'kg'\ n=4) following hpoic acid supplementation. No changes were demonstrated in the remaining subjects (n=5). It was concluded that improved glucose clearance during an OGTT following lipoic acid supplementation is assisted by increased muscle glucose oxidation through increased PDHa activation and decreased PDK activity in certain individuals.

The impact of the Multicolor Asian Lady Beetle (Harmonia axyridis) on wine quality /

The Impact of the Multicolor Asian Lady Beetle (Harmonia axyridis) on Niagara Wine Quality The possible influence of Harmonia axyridis (the Multicolored Asian Lady Beetle) on the sensory properties of wine was investigated. H. axyridis beetles were added to white and red grape musts at a rate of 0, 1 or 10 per L, and a trained panel evaluated the finished wines using flavor-profiling techniques. Significant modification of both wine aroma and flavor characteristics were observed in the 10 beetlelL treatments, with smaller effects noted at the 1 beetlelL rate. Vinification in the presence of H. axyridis gave higher intensity scores for peanut, bell pepper and asparagus aromas and flavors in the white wines, and peanut, asparagus/bell pepper, and earthy/herbaceous aromas and flavors in the red wines. In addition, sweet, acid and bitter tastes were affected in red wines, and a general trend of decreasing fruit and floral intensities with increasing beetle rate was observed in both white and red wines. 15 ngIL Isopropylmethoxypyrazine was added to control wines and sensory profiles similar to high beetle treatments were obtained, supporting the hypothesis that methoxypyrazines from beetles are implicated in the taint. A trained panel evaluated the treated wines after 10 months of aging using the same sensory methods described above. Sensory profiles were very similar. Fennenting in the presence of Harmonia Axyridis (HA) had little influence on the chemical composition of the ftnished wine. The notable exception IS Isopropylmethoxypyrazine content, which was assessed usmg GC-MS analysis and showed increased concentration with increasing beetle nwnber for both white and red wmes. The influence of potential remedial treatments on the sensory properties of white and red wines tainted by Harmonia axyridis were also investigated. Bentonite, activated charcoal, oak chips, de-odorized oak chips, and UV or light irradiation were applied to tainted wine, and these wines evaluated chemically and sensorially. Both white and red wines treated with oak chips had strong oak characteristics, which masked the Harmonia axyridis-associated aroma and flavour attributes. In red wine, asparagus/bell pepper characteristics were decreased by bentonite and charcoal treatments. Only activated charcoal significantly decreased methoxypyrazine levels and only in white wine.

The Arabidopsis NPR1 Protein Is a Receptor for the Plant Defense Hormone Salicylic Acid

Systemic Acquired Resistance (SAR) is a type of plant systemic resistance occurring against a broad spectrum of pathogens. It can be activated in response to pathogen infection in the model plant Arabidopsis thaliana and many agriculturally important crops. Upon SAR activation, the infected plant undergoes transcriptional reprogramming, marked by the induction of a battery of defense genes, including Pathogenesis-related (PR) genes. Activation of the PR-1 gene serves as a molecular marker for the deployment of SAR. The accumulation of a defense hormone, salicylic acid (SA) is crucial for the infected plant to mount SAR. Increased cellular levels of SA lead to the downstream activation of the PR-1 gene, triggered by the combined action of the Non-expressor of Pathogenesis-related Gene 1 (NPR1) protein and the TGA II-clade transcription factor (namely TGA2). Despite the importance of SA, its receptor has remained elusive for decades. In this study, we demonstrated that in Arabidopsis the NPR1 protein is a receptor for SA. SA physically binds to the C-terminal transactivation domain of NPR1. The two cysteines (Cys521 and Cys529), which are important for NPR1’s coactivator function, within this transactivation domain are critical for the binding of SA to NPR1. The interaction between SA and NPR1 requires a transition metal, copper, as a cofactor. Our results also suggested a conformational change in NPR1 upon SA binding, releasing the C-terminal transactivation domain from the N-terminal autoinhibitory BTB/POZ domain. These results advance our understanding of the plant immune function, specifically related to the molecular mechanisms underlying SAR. The discovery of NPR1 as a SA receptor enables future chemical screening for small molecules that activate plant immune responses through their interaction with NPR1 or NPR1-like proteins in commercially important plants. This will help in identifying the next generation of non-biocidal pesticides.