Browsing by Author "Surowiec, Kazimierz (TTU)"
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Item Augmenting Sulfur Metabolism and Herbivore Defense in Arabidopsis by Bacterial Volatile Signaling(2016) Aziz, Mina (TTU); Nadipalli, Ranjith K. (TTU); Xie, Xitao (TTU); Sun, Yan (TTU); Surowiec, Kazimierz (TTU); Zhang, Jin-Lin; Paré, Paul W. (TTU)Sulfur is an element necessary for the life cycle of higher plants. Its assimilation and reduction into essential biomolecules are pivotal factors determining a plant’s growth and vigor as well as resistance to environmental stress. While certain soil microbes can enhance ion solubility via chelating agents or oxidation, microbial regulation of plant-sulfur assimilation has not been reported. With an increasing understanding that soil microbes can activate growth and stress tolerance in plants via chemical signaling, the question arises as to whether such beneficial bacteria also regulate sulfur assimilation. Here we report a previously unidentified mechanism by which the growth-promoting rhizobacterium Bacillus amyloliquefaciens (GB03) transcriptionally activates genes responsible for sulfur assimilation, increasing sulfur uptake and accumulation in Arabidopsis. Transcripts encoding for sulfur-rich aliphatic and indolic glucosinolates are also GB03 induced. As a result, GB03-exposed plants with elevated glucosinolates exhibit greater protection against the generalist herbivore, Spodoptera exigua (beet armyworm, BAW). In contrast, a previously characterized glucosinolate mutant compromised in the production of both aliphatic and indolic glucosinolates is also compromised in terms of GB03-induced protection against insect herbivory. As with in vitro studies, soil-grown plants show enhanced glucosinolate accumulation and protection against BAW feeding with GB03 exposure. These results demonstrate the potential of microbes to enhance plant sulfur assimilation and emphasize the sophisticated integration of microbial signaling in plant defense.Item Caffeine Timing Improves Lower-Body Muscular Performance: A Randomized Trial(2020) Harty, Patrick S. (TTU); Zabriskie, Hannah A.; Stecker, Richard A.; Currier, Brad S.; Tinsley, Grant M. (TTU); Surowiec, Kazimierz (TTU); Jagim, Andrew R.; Richmond, Scott R.; Kerksick, Chad M.Little is known about the optimal time to consume caffeine prior to exercise to maximize the ergogenic benefits of the substance. Purpose: To determine the optimal pre-exercise time interval to consume caffeine to improve lower-body muscular performance. A secondary aim was to identify the presence of any sex differences in responses to timed caffeine administration. Methods: Healthy, resistance-trained males (n = 18; Mean±SD; Age: 25.1 ± 5.7 years; Height: 178.4 ± 7.1 cm; Body mass: 91.3 ± 13.5 kg; Percent body fat: 20.7 ± 5.2; Average caffeine consumption: 146.6 ± 100.3 mg/day) and females (n = 11; Mean ± SD; Age: 20.1 ± 1.6 years; Height: 165.0 ± 8.8 cm; Body mass: 65.8 ± 10.0 kg; Percent bodyfat: 25.8 ± 4.2; Average caffeine consumption: 111.8 ± 91.7 mg/day) participated in this investigation. In a randomized, double-blind, placebo-controlled, crossover fashion, participants consumed 6 mg·kg−1 caffeine or placebo solution at three time points: 2 h prior (2H), 1 h prior (1H), or 30 min prior (30M) to exercise testing. During three visits, caffeine was randomly administered at one time point, and placebo was administered at the other two time points. During one visit, placebo was administered at all three time points. Next, participants performed isometric mid-thigh pulls (IMTP), countermovement vertical jumps (CMVJ), and isometric/isokinetic knee extensor testing (ISO/ISOK). Results: Caffeine administered at 1H significantly improved absolute CMVJ and ISO performance relative to placebo. Mean CMVJ jump height was significantly higher during 1H compared to 30M. However, only caffeine administered at 30M significantly improved absolute measures of isokinetic performance. Analysis of the pooled caffeine conditions revealed that muscular performance was more consistently augmented by caffeine in males compared to females. Conclusions: Pre-exercise caffeine timing significantly modulated participant responses to the substance, with 1H exerting the most consistent ergogenic benefits relative to other time points, particularly compared to 2H. Male participants were found to respond more consistently to caffeine compared to female participants. These results suggest that active individuals can maximize the ergogenic effects of caffeine by consuming the substance ~1 h prior to the point when peak muscular performance is desired.Item Effect of Na+ on solvent extraction of alkaline earth metal cations by proton-ionizable calix[4]arenes(2010) Talanova, Galina G.; Talanov, Vladimir S.; Surowiec, Kazimierz (TTU); Bartsch, Richard A. (TTU)Metal ion recognition by proton-ionizable calixarenes is often affected by interference from the Na+ present in many aqueous solutions. To assess the Na+ -effect on calixarene selectivity towards alkaline earth metal cations (AEMC), competitive solvent extraction of Mg2+, Ca2+, Sr2+ , and Ba2+ from aqueous solutions into chloroform by di-ionizable calix[4]arene N- (trifluoromethylsulfonyl)carboxamides and corresponding carboxylic acids, conformationally mobile and restricted to cone, partial cone and 1,3-alternate conformations, was investigated in the absence and in the presence of aqueous-phase Na+ . The extraction selectivities were found to be altered due to contrasting Na+ -induced changes in the AEMC uptake. Observed increases in loadings of smaller AEMC are rationalized by their co-extraction with Na+.Item Metal ion complexation in acetonitrile by upper-rim benzyl-substituted, di-ionized calix[4]arenes bearing two dansyl fluorophores(2010) Ocak, Űmmühan; Ocak, Miraç; Shen, Xin (TTU); Gorman, Alexander H. (TTU); Surowiec, Kazimierz (TTU); Bartsch, Richard A. (TTU)The influence of Li+ , Na+ , K+ , Rb+ , Cs+ , Mg2+, Ca2+, Sr2+, Ba2+, Ag+ , Cd2+, Co2+, Fe2+, Hg2+ , Mn2+, Pb2+, Zn2+ and Fe3+ on the spectroscopic properties of two dansyl (1- dimethylaminonaphthalene-5-sulfonyl) groups linked to the lower rims of a series of three, structurally related, di-ionized calix[4]arenes is investigated by means of emission spectrophotometry. Di(tetramethylammonium) salts of the di-ionized ligands, L, L1 and L2, which differ in having no, two and four benzyl groups, respectively, on the upper rim of the calix[4]arene scaffold, are utilized for the spectrofluorimetric titration experiments in MeCN. On complexation by alkaline earth metal cations, the emission spectra undergo marked red shifts. Alkali metal cations cause fluorescence enhancement of benzyl-substituted di-ionized calix[4]arenes L1 and L2 with red shifts, except for Li+ and Cs+ . Transition metal cations and Pb2+ interact strongly with the ligands. In particular, Fe3+ , Hg2+ and Pb2+ cause greater than 99 % quenching of the dansyl fluorescence for all three ligands.Item Sterically congested, geminal aryl-substituted, proton-ionizable sym-dibenzo-16-crown-5 lariat ethers: synthesis and alkali metal cation extraction(2010) Tu, Chuqiao (TTU); Jang, Youngchan (TTU); Bates, Carrie L. (TTU); Gega, Jerzy (TTU); Surowiec, Kazimierz (TTU); Bartsch, Richard A. (TTU)Three series of proton-ionizable sym-dibenzo-16-crown-5 ethers with sterically demanding 1- naphthyl, 2-naphthyl, and 9-phenanthryl geminal groups are synthesized and characterized. Variation of the proton-ionizable group includes oxyacetic acid and N-(X)sulfonyl oxyacetamide units with X = Me, Ph, C6H4-4-NO2, and CF3. For the latter series, variation of X provides 'tunable' acidity of the ligand. The metal ion-complexing properties of the proton-ionizable sym- (aryl)dibenzo-16-crown-5 compounds are probed by competitive solvent extraction of alkali metal cations from aqueous solutions into chloroform.