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Caloric restriction (CR) has shown to increase lifespan in several model organisms including Drosophila melanogaster. Several pathways have been studied in order to better understand the biochemical mechanisms for this increase in longevity. Methionine has been shown to play a role in promoting antioxidant responsiveness to oxidative stress and other forms of cellular degeneracy. A reduction of dietary methionine has shown to increase longevity. The experiments run in this study were designed to bolster these findings. If an increase in dietary methionine limited lifespan, a corol could be drawn to methionine restriction studies. This experiment dealt with the effects of dietary methionine supplementation in conjunction with caloric restriction, and how these effects are linked to longevity in D. melanogaster. The results of these studies were consistent with previous caloric restriction studies. However, the effects of methionine on CR proved to be inconclusive.
As the number of drug-resistant strains of microorganisms increases, scientists are in search of new ways to treat resistant infections. Essential oils have been used for centuries in homeopathic medicine and many are claimed to have antibacterial and antiviral properties. Several homeopathic substances were tested first using the disc diffusion method to determine activity against selected bacterial and fungal species. Microorganisms used for the study were Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Candida kejyr, Rhodotorula rubra and Saccharomyces cerevisiae. Substances with the most consistent action against microorganisms were tested further using a broth microdilution method to determine a minimum inhibitory concentration for each substance. Rhodotorula rubra was eliminated from the broth microdilution assay due to the difficulty in culturing the microorganism and its low incidence of infection. Homeopathic substances tested were garlic, honey, tea tree oil, oregano oil, thyme oil, olive leaf extract, wintergreen oil, and lemon oil. The most effective were tea tree oil, oregano oil, thyme oil, wintergreen oil, and lemon oil. Oregano oil was determined to have the greatest antimicrobial activity with a mean minimum inhibitory concentration (MIC) of 0.56 (%v/v) followed by thyme oil with a mean MIC of 2.47 (%v/v).
Susceptibility testing against gram-positive and gram-negative bacteria was carried out using fresh aqueous, heated aqueous and dried powder solutions of garlic. Pseudomonas aeruginosa was not inhibited by the garlic extract. Dried garlic powder showed comparable antimicrobial properties against Staphylococcus aureus and Salmonella typhimurium as fresh unheated garlic extract. However, when the aqueous garlic extract was subjected to heating for 20 minutes, its antimicrobial property was significantly reduced. The disk diffusion technique appears to be more reliable for susceptibility testing than the agar-gel diffusion technique, since the disk diffusion test correlates well with the results of the Minimum Inhibitory Concentration (MIC). Our results show that garlic disks of 6.25 mg should be used for susceptibility testing. Zone sizes of 29 mm and above should indicate susceptibility for S. aureus.
Fluorine has no known physiological role in grasses, yet is an essential nutrient for grazing animals. The evolution of an uptake mechanism for F must be examined in the context of the coevolution of grasses and grazers. The objective of this study was to determine whether uncultivated grasses buffer the uptake of F in a range acceptable for grazing animals and whether cultivated grasses have lost this buffering mechanism. The uncultivated grasses big bluestem (Andropogon gerardii Vitman), little bluestem (Schizachyrium scoparium (Michx.) Nash) and switchgrass (Panicum virgatum L.), and the cultivated grasses wheat (Triticum aestivum L.), rye (Secale cereale L.) and oats (Avena sativa L.), were grown in a greenhouse and watered with NaF at F concentrations in the range 0–9 mg/kg. Total F concentrations of plant shoots were determined by the alkali-fusion method. Average F contents for uncultivated grasses (29 mg/kg for big bluestem, 26 mg/kg for little bluestem, 25 mg/kg for switchgrass) were below the upper limit for dairy cattle (40 mg/kg), while average F contents for cultivated grasses (51 mg/kg for wheat, 97 mg/kg for rye, 99 mg/kg for oats) were well above the upper limit for cattle. For the uncultivated grasses, plant F content did not correlate with F concentration of irrigation water (R2 = 0.13 for big bluestem, R2 = 0.14 for little bluestem, R2 = 0.22 for switchgrass), while correlations were moderate to good for cultivated grasses (R2 = 0.61 for wheat, R2 = 0.52 for rye, R2 = 0.52 for oats).