This work consists of four sections: 1) the adsorption behavior of bovine serum albumin (BSA) by three types of oxide nanoparticles (NPs), TiO2 (50 ± 5 nm), SiO2 (30 ± 5nm), and Al2O3 (150 ± 5 nm for α type and 60 ± 5 nm for γ type) in deionized water; 2) phosphate adsorption on these oxide NPs and bulkparticles (BPs); 3) influence of phosphate ions on BSA adsorption; and 4) BSA desorption from oxide NPs in phosphate solution. BPs were also used for comparison with NPs. For BSA adsorption in deionized water, the adsorption maxima on oxide particles are controlled by the surface area and hydrogen content, while the adsorption process is primarily induced by electrostatic interaction, hydrophobic interaction, and ligand exchange between BSA and oxide surfaces. With increasing of hydrogen content, the BSA adsorption mechanism switches from a mainly hydrophobic interaction to hydrogen bonding and ligand exchange. Calculations based on surface area and BSA size, suggest that a multilayer of BSA covers α-Al2O3, but only a single layer surrounds the other oxide particle surfaces. BPs lead to greater conformational change of BSA molecules after their adsorption on the surfaces of oxide particles, although NPs adsorbed more BSA than BPs by weight. For phosphate, e adsorption process is mainly governed by the surface charge of the oxides. Strong electrostatic repulsion can prevent the adsorption of phosphate ions on an oxide surface. Meanwhile, a good linear relationship was observed between surface-normalized BSA adsorption maxima and surface charge of the oxides. For the influence of phosphate ions on BSA adsorption, BSA adsorption is suppressed by phosphate ions, while BSA molecules have no influence on phosphate adsorption. The competition between BSA molecules and phosphate ions is regulated by electrostatic interaction, the hydrogen content of the oxides and oxide surface area (especially micropore surface area). The difference of influence between hydrophobic and hydrophilic interactions on BSA adsorption reduces with the increase of phosphate concentration. Moreover, quantification was employed to calculate the displacing amount of phosphate ions to BSA molecules in competition. The displacing amount of phosphate ions is regulated by micropore surface area, and shows a good linearity with the hydrogen content. For BSA desorption, the BSA desorption hysteresis is observed for SiO2 NPs due to the high aggregation of this type of NPs. The aggregation of NPs can entrap BSA molecules in the closed interstitial spaces, leading to the BSA desorption hysteresis. For α-Al2O3 and γ- Al2O3 NPs, the hysteresis is observed only at low BSA concentration due to the influence of BSA molecules and electrostatic repulsion to the suspension of NPs. For TiO2 NPs, no significant hysteresis is observed because of their low aggregation and strong electrostatic repulsion. Phosphate adsorbed amounts remain unchanged within the adsorption and two-cycle desorption, indicating the entrapped BSA molecules may not bond to the oxide NPs.

Switchgrass (Panicum virgatum L.) is a warm-season perennial being considered as a biofuel to meet energy challenges. In Massachusetts, a small state where the price of land is expensive, farmers want to determine if switchgrass can produce sufficient yields for consecutive years to warrant its production. The objective of this study was to determine what harvest management practices affect the vigor and health of switchgrass and which varieties produce the best yields for biofuel production. Four experiments were conducted from 2009-2012. Twelve varieties were tested to determine their viability in the Massachusetts climate. Five were chosen for further chemical analysis. All varieties were harvested in August (senescence), November (killing frost), and April (early spring). A high yielding variety, Cave-in-Rock, known to grow well in northern latitudes, was chosen for more extensive research. In one experiment, a young stand, three years old, received three nitrogen treatments, was cut at two heights, and was harvested at three different times during the year. A mature stand, seven years old, of the same variety located on conservation land, was harvested three times at two cutting heights. These experiments were done to provide projections on the expected yields over the plant's 10 to 20 year life cycle. In our final experiment Switchgrass was harvested every two weeks from September to November. A caliometer tracked how much energy was present in the dry matter throughout the growing season. Dry matter yield, chemical constituents, and carbohydrate reserves in the below ground tissues were measured as indicator variables to determine the health and quality of yield. Harvest time was the most significant variable observed.

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The mechanism of light control of leaf abscission was studied in coleus (Coleus blumei Benth.) and mung bean (Vigna radiata (L.) Wilczek) cuttings by evaluating the roles of IAA, carbohydrate, and cellulase in the process of abscission. Treatment of the cuttings with red light maintained high break strength in the abscission zone in both tested plants, whereas treatment with far-red light initiated a dramatic increase in abscission. Leaf diffusate collected from red light treated leaves contained 3 times more IAA than that collected from leaves maintained in the dark or treated with far-red light. Treatment of the cuttings with 2,3,5-triiodobenzoic acid (TIBA), an auxin transport inhibitor, eliminated the inhibitory effect of red light on abscission. No significant difference in IAA oxidase activity was detected among the light treatments. The rate of decarboxylation of IAA in leaf tissue treated with red light, however, was higher than in the leaves receiving dark or far-red light. Conversion of tryptophan to IAA was higher in red light-treated leaf blades than in leaves maintained in dark or treated with far-red light. Treatment of mung bean leaf cuttings with red or far-red light, produced no significant differences in the content of fructose 6-phosphate, glucose plus fructose, sucrose, total soluble sugars, or starch. A higher level of glucose 6-phosphate was detected in red light-treated leaves. Loading the tissue with sucrose, a sugar reported to affect organ abscission, did not change the effect of light on abscission. The differences in the rate of IAA synthesis observed in leaf tissue under various light treatments is proposed as the controlling mechanism for light regulation of abscission. Total sugar or starch content in the leaf blade was not related to leaf abscission, indicating that photoassimilate in leaf tissue was not involved in light regulation of abscission. While cellulase activity in the abscission zone accounts for the decrease in break strength of abscission zone, the enzyme per se was not affected by light.

Experiments were initiated to determine if calcium (Ca) acted as a 'second messenger' mediating hormone response in apple. Benzyladenine (BA) and gibberellins GA$\sb4$ or GA$\sb{4/7}$ were applied alone or in combination with either verapamil or trifluoperazine, as a foliar spray or by injection into the calyx end of 'Delicious' around two weeks after full bloom. There were few gibberellin and Ca modifier interactions. It is concluded that if Ca is acting as a 'second messenger' in mediating hormone response, its contribution is peripheral at best. Experiments were conducted to examine the relationship between flowering and fruit set in apple and endogenous levels of polyamines in developing fruit and leaves. Cytokinin (BA), gibberellins (GA$\sb4$, GA$\sb7$, GA$\sb{4/7}$) and 92 percent shade were used to modify flowering and fruit set. In addition, in experiments with 'Cortland' and 'Idared', differences between fruit on the same cluster were evaluated. In general, polyamines within the developing fruit decreased with fruit development. Spermidine was the predominant polyamine, followed by putrescine and then spermine. Small fruit in a cluster generally contained higher levels of polyamines than large or abscising fruit. No relationship was found between endogenous polyamines and flower bud initiation. In 'Cortland', 'Golden Delicious', and 'Idared', peaks occurred in putrescine and spermine content in developing fruit just prior to abscission peaks associated with 'June drop'. A cyclic pattern of putrescine in small 'Idared' fruit may be related to natural abscission waves in apple. Putrescine and spermidine levels in 'Idared' leaves were reduced with a 92 percent shade treatment. Two experiments were initiated to examine the relationship between exogenous hormone application and exogenous levels of cytokinins in developing apple leaves. A foliar application of BA produced a 48-fold increase in trans-zeatin riboside-like activity in developing leaves.

TCV isolate, TCV-M, supports a family of satellite (sat-) RNAs. The virulent sat-RNA C intensifies TCV symptoms on turnip cultivar Just Right. In this thesis, I report that sat-RNA C (356 b) exacerbates symptoms on all hosts where TCV produces visible symptoms including cultivars of Brassica rapa and Arabidopsis thaliana. This finding has led to studies of TCV-resistance using A. thaliana, a small plant with a well characterized genome, as a host. After screening over 6,000 M2 A. thaliana plants from EMS treated Columbia cultivar seeds and 22 ecotypes of A. thaliana, ecotype Dijon was found to be resistant to TCV. A second isolate, TCV-B, supports an RNA species with a size similar to that of sat-RNA C. Northern hybridization and cDNA cloning and sequencing demonstrate that this RNA is actually a defective interfering (DI) RNA, denoted DI RNA G. Infection of turnip with virus derived from cloned transcripts of TCV-B resulted in de novo generation of a DI RNA, DI1 RNA. Unlike DI RNAs associated with other plant viruses (or animal viruses), TCV DI RNAs intensify TCV symptoms. To understand sequences required for DI RNA infectivity, a series of mutation have been generated in a full length cDNA copy of DI RNA G. Stepwise deletions at base 98 of DI RNA G, at which an Apa I linker had been inserted, has shown that DI RNA GA (DI RNA G with a 8-base insertion at base 98) harboring deletions of bases 74-98 or less are infectious. However, deletion of bases 73-98 or more abolishes RNA infectivity. DI RNA GA with a deletion of bases 107-124 is infectious. However, DI RNA GA harboring a deletion of bases 107-138 is not infectious. I have found that infectivity of RNA harboring 31- or 32-base deletions can be restored by inserting foreign sequences into deletion sites. This implies that at least 71 bases (including the 8-base insertion) in DI RNA GA near the 5$\sp\prime$ end are not specifically required for RNA infectivity. By combining deletions of infectious clones to generate larger deletions (40 or 43 bases deleted), I demonstrate that the infectivity of the RNA is abolished. This result suggests that size of the DI RNA is important in maintaining RNA infectivity.

Superficial scald, a physiological disorder of apples, develops during storage, and is believed to result from the oxidation of $\propto$ farnesene to conjugated trienes. Antioxidants are believed to protect against this oxidation, thus providing scald resistance. The hypothesis examined in this study was that temperatures below 10$\sp\circ$C before harvest facilitate the accumulation of antioxidants in the apple peel, and that this effect is enhanced by ripening and light. Cortland and Delicious apples were harvested following exposure to increasing hours below 10$\sp\circ$C during three years. Cortland apples were sprayed with ethephon to induce ripening at warm temperatures, and were bagged in late August to produce ripening at low light intensities, both during two years. Percent inhibition of oxidation and water-soluble reducing activities, as well as concentrations of $\propto$ tocopherol, ascorbic acid, glutathione, $\propto$ farnesene, conjugated trienes and several pigments, were determined at harvest and following intervals of storage. Scald development was determined after 3 to 5 months of storage at 0$\sp\circ$C. Correlations and regressions demonstrated that increasing exposure to temperatures below 10$\sp\circ$C was the primary factor in development of scald resistance. Less resistance developed when low light intensity existed during cool periods. Ripening alone was only a small factor in development of scald resistance. Cool preharvest temperatures slightly increased the concentrations of $\propto$ tocopherol and carotenes, and slightly increased water-soluble reducing capacity and percent inhibition of oxidation. Ripening increased both percent inhibition of oxidation and total water-soluble reducing activities, and increased concentrations of $\propto$ tocopherol, carotenes and ascorbic acid. Reduced light intensity (bagging) decreased concentrations of $\propto$ tocopherol, carotenes, and ascorbic acid, as well as total water-soluble reducing capacity. However, percent inhibition of oxidation and glutathione were not significantly influenced. During storage, as conjugated trienes accumulated, the $\propto$ tocopherol and carotene concentrations increased, while total water-soluble reducing capacity, ascorbic acid, and glutathione decreased. Although some support is given to the widely accepted model of scald development, it was concluded that while antioxidants play a role in scald resistance, they are probably not the key factor.