Current Search: Molecular (x)
Pages
-
-
Title
-
The Relationship Between DNA's Physical Properties and the DNA Molecule's Harmonic Signature, and Related Motion in Water--A Computational Investigation.
-
Creator
-
Boyer, Victor, Proctor, Michael, Thompson, William, Karwowski, Waldemar, Calloway, Richard, University of Central Florida
-
Abstract / Description
-
This research investigates through computational methods whether the physical properties of DNA contribute to its harmonic signature, the uniqueness of that signature if present, and motion of the DNA molecule in water. When DNA is solvated in water at normal 'room temperature', it experiences a natural vibration due to the Brownian motion of the particles in the water colliding with the DNA. The null hypothesis is that there is no evidence to suggest a relationship between DNA's motion and...
Show moreThis research investigates through computational methods whether the physical properties of DNA contribute to its harmonic signature, the uniqueness of that signature if present, and motion of the DNA molecule in water. When DNA is solvated in water at normal 'room temperature', it experiences a natural vibration due to the Brownian motion of the particles in the water colliding with the DNA. The null hypothesis is that there is no evidence to suggest a relationship between DNA's motion and strand length, while the alternative hypothesis is that there is evidence to suggest a relationship between DNA's vibrational motion and strand length. In a similar vein to the first hypothesis, a second hypothesis posits that DNA's vibrational motion may be dependent on strand content. The nature of this relationship, whether linear, exponential, logarithmic or non-continuous is not hypothesized by this research but will be discovered by testing if there is evidence to suggest a relationship between DNA's motion and strand length. The research also aims to discover whether the motion of DNA, when it varies by strand length and/or content, is sufficiently unique to allow that DNA to be identified in the absence of foreknowledge of the type of DNA that is present in a manner similar to a signature. If there is evidence to suggest that there is a uniqueness in DNA's vibrational motion under varying DNA strand content or length, then additional experimentation will be needed to determine whether these variances are unique across small changes as well as large changes, or large changes only. Finally, the question of whether it might be possible to identify a strand of unique DNA by base pair configuration solely from its vibrational signature, or if not, whether it might be possible to identify changes existing inside of a known DNA strand (such as a corruption, transposition or mutational error) is explored. Given the computational approach to this research, the NAMD simulation package (released by the Theoretical and Computational Biophysics Group at the University of Illinois at Urbana-Champaign) with the CHARMM force field would be the most appropriate set of tools for this investigation (Phillips et al., 2005), and will therefore be the toolset used in this research. For visualization and manipulation of model data, the VMD (Visual Molecular Dynamics) package will be employed. Further, these tools may be optimized and/or be aware of nucleic acid structures, and are free. These tools appear to be sufficient for this task, with validated fidelity of the simulation to provide vibrational and pressure profile data that could be analyzed; sufficient capabilities to do what is being asked of it; speed, so that runs can be done in a reasonable period of time (weeks versus months); and parallelizability, so that the tool could be run over a clustered network of computers dedicated to the task to increase the speed and capacity of the simulations. The computer cluster enabled analysis of 30,000 to 40,000 atom systems spending more than 410,000 CPU computational hours of hundreds of nano second duration, experimental runs each sampled 500,000 times with two-femtosecond (")frames.(")Using Fourier transforms of run pressure readings into frequencies, the simulation investigation could not reject the null hypotheses that the frequencies observed in the system runs are independent on the DNA strand length or content being studied. To be clear, frequency variations were present in the in silicon replications of the DNA in ionized solutions, but we were unable to conclude that those variations were not due to other system factors. There were several tests employed to determine alternative factors that caused these variations. Chief among the factors is the possibility that the water box itself is the source of a large amount of vibrational noise that makes it difficult or impossible with the tools that we had at our disposal to isolate any signals emitted by the DNA strands. Assuming the water-box itself was a source of large amounts of vibrational noise, an emergent hypothesis was generated and additional post-hoc testing was undertaken to attempt to isolate and then filter the water box noise from the rest of the system frequencies. With conclusive results we found that the water box is responsible for the majority of the signals being recorded, resulting in very low signal amplitudes from the DNA molecules themselves. Using these low signal amplitudes being emitted by the DNA, we could not be conclusively uniquely associate either DNA length or content with the remaining observed frequencies. A brief look at a future possible isolation technique, wavelet analysis, was conducted. Finally, because these results are dependent on the tools at our disposal and hence by no means conclusive, suggestions for future research to expand on and further test these hypothesis are made in the final chapter.
Show less
-
Date Issued
-
2015
-
Identifier
-
CFE0005930, ucf:50835
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFE0005930
-
-
Title
-
CONFORMATIONS OF TRICYANOFURAN-TYPE METASTABLE-STATE PHOTOACIDS.
-
Creator
-
Arias, Juan E, Chumbimuni-Torres, Karin Y., University of Central Florida
-
Abstract / Description
-
Tricyanofuran-type metastable-state photoacids, relative newcomers to the field of photochromism, outperform traditional light-controlled molecular switches in regards to applicability in biological systems. In a preliminary attempt to understand the underlying processes that govern these compounds, this thesis project establishes the isomeric identity of an unsubstituted tricyanofuran-type metastable-state photoacid, referred to as TCF 1 in this work. Two-dimensional nuclear magnetic...
Show moreTricyanofuran-type metastable-state photoacids, relative newcomers to the field of photochromism, outperform traditional light-controlled molecular switches in regards to applicability in biological systems. In a preliminary attempt to understand the underlying processes that govern these compounds, this thesis project establishes the isomeric identity of an unsubstituted tricyanofuran-type metastable-state photoacid, referred to as TCF 1 in this work. Two-dimensional nuclear magnetic resonance experiments are employed to experimentally determine the presence and identity of the open-form TCF 1 isomers. Electronic structure calculations are then used to provide quantitative insight into the experimental results. Experiment and theory show that four out of eight possible open-form isomers exist in solution. To validate the information obtained theoretically, the calculation methodologies are tested against experimental chemical shifts. The impressive agreement with the experiments gives credibility to the picture painted by the theoretical models.
Show less
-
Date Issued
-
2019
-
Identifier
-
CFH2000470, ucf:45707
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFH2000470
-
-
Title
-
SYMMETRY IN THE DISSOCIATIVE RECOMBINATION OF POLYATOMIC IONS AND IN ULTRA-COLD FEW BODY COLLISIONS.
-
Creator
-
Douguet, Nicolas, Kokoouline, Viatcheslav, University of Central Florida
-
Abstract / Description
-
We discuss the role of symmetries in the dissociative recombinations (DR) of three polyatomic ions, namely the linear HCO+ (formyl) ion and the two highly symmetric H3+ and H3O+ (hydronium) molecular ions. Regarding the HCO+ ion, we apply a quantum mechanical treatment using the Multi-channel Quantum Defect Theory (MQDT) formalism to describe the ion-electron scattering process. Our study takes into account the Renner-Teller effect in order to model the non Born-Oppenheimer vibronic coupling...
Show moreWe discuss the role of symmetries in the dissociative recombinations (DR) of three polyatomic ions, namely the linear HCO+ (formyl) ion and the two highly symmetric H3+ and H3O+ (hydronium) molecular ions. Regarding the HCO+ ion, we apply a quantum mechanical treatment using the Multi-channel Quantum Defect Theory (MQDT) formalism to describe the ion-electron scattering process. Our study takes into account the Renner-Teller effect in order to model the non Born-Oppenheimer vibronic coupling in linear polyatomic ions. The coupling has shown to represent the main mechanism responsible for electronic capturing in highly excited Rydberg states associated with excited vibrational levels of the ionic core. We consider all internal degrees of freedom of HCO+ and obtain the dissociative cross section as a function of the incident electron kinetic energy. We have also improved the theoretical approach by including the large permanent dipole moment of HCO+ using a generalization of the MQDT formalism. To our knowledge, this is the first time the permanent dipole moment of an ion is included in a DR study. The obtained results are in good agreement with experimental data. W also study the DR of H3+ and H3O+ symmetric ions using a simplified theoretical treatment, which focuses on the key ingredient of the DR process, the electron capture in the first excited degenerate vibrational normal mode of the ions through non Born-Oppenheimer Jahn-Teller coupling. For both ions the obtained cross sections are in very good agreement with the available experimental data. Moreover, in the case of H3+, the results reproduce previous calculations from two independent theoretical studies. Finally, we investigate the role of symmetries in few body ultra-cold collisions by considering both three and four identical atoms systems. We derive allowed rearrangements of different fragments of the system, satisfying the complete symmetry of the molecular Hamiltonian. For that purpose we establish a correspondence between constants of motion of the system in different large-distance configurations and irreducible representations of the total symmetry group. Selection rules (forbidden transitions) and allowed states, which depend on the fermionic or bosonic nature of the atoms, can be derived from these results.
Show less
-
Date Issued
-
2010
-
Identifier
-
CFE0003552, ucf:48896
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFE0003552
-
-
Title
-
STUDY OF THE EGFR, SRC AND STAT3 PATHWAY IN PANCREATIC CANCER.
-
Creator
-
Jaganathan, Soumya, Turkson, James, University of Central Florida
-
Abstract / Description
-
Cancer is associated with many molecular aberrations that support the malignant phenotype. In that regard, aberrant activation of epidermal growth factor receptor (EGFR), Src, and signal transducer and activator of transcription 3 (Stat3) occur concurrently in pancreatic cancer and are implicated in the disease phenotype. Notwithstanding, increasing evidence indicates that therapies that target only EGFR or Src are rather ineffective in modulating the cancer phenotype. The poor therapeutic...
Show moreCancer is associated with many molecular aberrations that support the malignant phenotype. In that regard, aberrant activation of epidermal growth factor receptor (EGFR), Src, and signal transducer and activator of transcription 3 (Stat3) occur concurrently in pancreatic cancer and are implicated in the disease phenotype. Notwithstanding, increasing evidence indicates that therapies that target only EGFR or Src are rather ineffective in modulating the cancer phenotype. The poor therapeutic outcome of the monotherapies targeting EGFR or Src may in part be due to the increased incidence of signaling cross-talks among aberrant signaling pathways in cancer. Molecular details of the signaling integration between EGFR, Src and Stat3, however, are lacking. Understanding how the aberrant EGFR, Src and Stat3 pathways are integrated in pancreatic cancer would facilitate the design of effective multiple-targeted, clinically feasible therapeutic modalities. Our study shows that in pancreatic cancer cell lines, aberrant Src activity promotes abnormal EGFR activation through the phosphorylation of the EGFR motifs, Tyr845, Tyr1068 and Tyr1086. Furthermore, aberrantly-active EGFR and Src together induce constitutive activation of Stat3 in pancreatic cancer cells. Evidence further shows that EGFR, Src and Stat3 physically associated into a heteromeric complex. Significantly, the EGFR, Src and Stat3 heteromeric complex is detectable in the nucleus and functions as a transcriptionally-active complex to induce the c-Myc gene. Of therapeutic significance, the concurrent inhibition of Stat3 and EGFR or Src promoted greater viability loss and apoptosis of pancreatic cancer cells in vitro, and induced stronger tumor growth inhibition in xenografts of human pancreatic cancer. Altogether, our studies suggest that the heteromeric EGFR, Src, and Stat3 complex may serve as an additional novel mechanism of support of the pancreatic cancer phenotype. Furthermore, our studies provide evidence that the concurrent targeting of Stat3 and EGFR or Stat3 and Src could be a more effective therapeutic approach for human pancreatic cancer.
Show less
-
Date Issued
-
2010
-
Identifier
-
CFE0003417, ucf:48383
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFE0003417
-
-
Title
-
SPIN QUANTUM DYNAMICS IN MOLECULAR MAGNETS.
-
Creator
-
Henderson, John, del Barco, Enrique, University of Central Florida
-
Abstract / Description
-
Molecular magnets are ideal systems to probe the realm that borders quantum and classical physics, as well as to study decoherence phenomena in nanoscale systems. The control of the quantum behavior of these materials and their structural characteristics requires synthesis of new complexes with desirable properties which will allow probing of the fundamental aspects of nanoscale physics and quantum information processing. Of particular interest among the magnetic molecular materials are...
Show moreMolecular magnets are ideal systems to probe the realm that borders quantum and classical physics, as well as to study decoherence phenomena in nanoscale systems. The control of the quantum behavior of these materials and their structural characteristics requires synthesis of new complexes with desirable properties which will allow probing of the fundamental aspects of nanoscale physics and quantum information processing. Of particular interest among the magnetic molecular materials are single-molecule magnets (SMMs) and antiferromagnetic (AFM) molecular wheels in which the spin state of the molecule is known to behave quantum mechanically at low temperatures. In previous experiments the dynamics of the magnetic moment of the molecules is governed by incoherent quantum tunneling. Short decoherence times are mainly due to interactions between molecular magnets within the crystal and interactions of the electronic spin with the nuclear spin of neighboring ions within the molecule. This decoherence problem has imposed a limit to the understanding of the molecular spin dynamics and the sources of decoherence in condensed matter systems. Particularly, intermolecular dipolar interactions within the crystal, which shorten the coherence times in concentrated samples, have stymied progress in this direction. Several recent works have reported a direct measurement of the decoherence time in molecular magnets. This has been done by eliminating the dephasing created by dipolar interactions between neighboring molecules. This has been achieved by a) a dilution of the molecules in a liquid solution to decrease the dipolar interaction by separating the molecules, and b) by polarizing the spin bath by applying a high magnetic field at low temperatures. Unfortunately, both approaches restrict the experimental studies of quantum dynamics. For example, the dilution of molecular magnets in liquid solution causes a dispersion of the molecular spin orientation and anisotropy axes, while the large fields required to polarize the spin bath overcome the anisotropy of the molecular spin. In this thesis I have explored two methods to overcome dipolar interactions in molecular magnets: a) studying the dynamics of molecular magnets in single crystals where the separation between magnetic molecules is obtained by chemical doping or where the high crystalline quality allows observations intrinsic to the quantum mechanical nature of the tunneling of the spin, and b) studying the electronic transport through an individual magnetic molecule which has been carefully placed in a single-electron transistor device. I have used EPR microstrip resonators to measure Fe17Ga molecular wheels within single crystals of Fe18 AFM wheels, as well as demonstrating, for the first time in a Single Molecule Magnet, the complete suppression of a Quantum Tunneling of the Magnetization transition forbidden by molecular symmetry.
Show less
-
Date Issued
-
2009
-
Identifier
-
CFE0002799, ucf:48117
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFE0002799
-
-
Title
-
Electrostatic control over temperature-dependent tunneling across single-molecule junctions.
-
Creator
-
Rodriguez Garrigues, Alvar, Del Barco, Enrique, Flitsiyan, Elena, Ishigami, Masa, Hernandez, Eloy, University of Central Florida
-
Abstract / Description
-
The aim of the present dissertation is to improve the understanding and methodology of temperature-dependent tunnel conduction through individual molecules by single-electron transport spectroscopy. New advances in electrochemistry present individual molecular diodes as a realistic option for the implementation on molecular circuits thanks to their high current rectification ratios. Therefore, a major requisite in this field is to understand and control the conduction behaviors for a large...
Show moreThe aim of the present dissertation is to improve the understanding and methodology of temperature-dependent tunnel conduction through individual molecules by single-electron transport spectroscopy. New advances in electrochemistry present individual molecular diodes as a realistic option for the implementation on molecular circuits thanks to their high current rectification ratios. Therefore, a major requisite in this field is to understand and control the conduction behaviors for a large variety of conditions. This work focuses on the electric conduction through ferrocene-based molecules as a function of temperatures within a wide range of bias and gate voltages by means of three-terminal electromigrated-broken single-electron transistors (SETs).The results show that the temperature dependence of the current (from 80 to 260 K) depends strongly on the bias and gate voltages, with areas in where the current increases exponentially with temperature (at the Coulomb blockade regimes), and others where the increase of the temperature makes the current only to vary slightly (at resonance) or to decrease monotonically (at the charge degeneracy points). These different observed behaviors of the tunneling current with increasing temperatures can be well explained by a formal single-level coherent tunneling model where the temperature dependence relies on the thermal broadening of the Fermi distributions of the electrons in the leads. The model portraits the molecule as a localized electrostatic level capacitively coupled to the transistor leads, and the electrical conduction through the junction as coherent sequential tunneling.
Show less
-
Date Issued
-
2016
-
Identifier
-
CFE0006171, ucf:51132
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFE0006171
-
-
Title
-
ESTIMATION OF TANGENTIAL MOMENTUM ACCOMMODATION COEFFICIENT USING MOLECULAR DYNAMICS SIMULATION.
-
Creator
-
Finger, George, Kapat, Jayanta, University of Central Florida
-
Abstract / Description
-
The Tangential Momentum Accommodation Coefficient (TMAC) is used to improve the accuracy of fluid flow calculations in the slip flow regime. Under such conditions (indicated by Knudsen number greater than 0.001), the continuum assumption that a fluid velocity at a solid surface is equal to the surface velocity is inaccurate because relatively significant fluid "slip" occurs at the surface. Prior work has not led to a method to quickly estimate a value for TMAC - it is frequently assumed. In...
Show moreThe Tangential Momentum Accommodation Coefficient (TMAC) is used to improve the accuracy of fluid flow calculations in the slip flow regime. Under such conditions (indicated by Knudsen number greater than 0.001), the continuum assumption that a fluid velocity at a solid surface is equal to the surface velocity is inaccurate because relatively significant fluid "slip" occurs at the surface. Prior work has not led to a method to quickly estimate a value for TMAC - it is frequently assumed. In this work, Molecular Dynamics techniques are used to study the impacts of individual gas atoms upon solid surfaces to understand how approach velocity, crystal geometry and interatomic forces affect the scattering of the gas atoms, specifically from the perspective of tangential momentum. It is a logical step in the development of a comprehensive technique to estimate total coefficient values to be used by those investigating flows in micro- and nano-channels or on orbit spacecraft where slip flow occurs. TMAC can also help analysis in transitional or free molecular regimes of flow. The gas solid impacts were modeled using Lennard Jones potentials. Solid surfaces were modeled with approximately 3 atoms wide by 3 atoms deep by 40 or more atoms long. The crystal surface was modeled as a Face Centered Cubic (100). The gas was modeled as individual free gas atoms. Gas approach angles were varied from 10° to 70° from normal. Gas speed was either specified directly or by way of a ratio relationship with the Lennard-Jones energy potential (Energy Ratio). In order to adequately model the trajectories and maintain conservation of energy, very small time steps (on the order of 0.0005 ô , where ô is the natural time unit) were used. For each impact the initial and final tangential momenta were determined and after a series of many impacts, a value of TMAC was calculated for those conditions. The modeling was validated with available experimental data for He gas atoms at 1770 m/s impacting Cu over angles ranging from 10° to 70°. The model agreed within 3% of the experimental values and correctly predicted that the coefficient changes with angle of approach. Molecular Dynamics results estimate TMAC values from a high of 1.2 to a low of 0.25, generally estimating a higher coefficient at the smaller angles. TMAC values above 1.0 indicate backscattering, which has been experimentally observed in numerous instances. The ratio of final to initial momenta, when plotted for a given sequence of gas atoms spaced across a lattice cycle typically follows a discontinuous curve, with continuous portions indicating forward and back scattering and discontinuous portions indicating multiple bounces. Increasing the Energy Ratio above a value of 5 tends to decrease the coefficient at all angles. Adsorbed layers atop a surface influence the coefficient similar to their Energy Ratio. The results provide encouragement to develop the model further, so as to be able in the future to evaluate TMAC for gas flows with Maxwell temperature distributions involving numerous impact angles simultaneously.
Show less
-
Date Issued
-
2005
-
Identifier
-
CFE0000760, ucf:46567
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFE0000760
-
-
Title
-
LATTICE VIBRATION STUDY OF SILICA NANOPARTICLE IN SUSPENSION.
-
Creator
-
Sachdeva, Parveen, Kumar, Ranganathan, University of Central Florida
-
Abstract / Description
-
In recent years considerable research has been done in the area of "nanofluids". Nanofluids are colloidal suspensions of nanometer size metallic or oxide particles in a base fluid such as water, ethylene glycol. Nanofluids show enhanced heat transfer characteristics compared to the base fluid. The thermal transport properties of nanofluids depend on various parameters e.g. interfacial resistance, Brownian motion of particles, liquid layering at the solid-liquid interface and clustering of...
Show moreIn recent years considerable research has been done in the area of "nanofluids". Nanofluids are colloidal suspensions of nanometer size metallic or oxide particles in a base fluid such as water, ethylene glycol. Nanofluids show enhanced heat transfer characteristics compared to the base fluid. The thermal transport properties of nanofluids depend on various parameters e.g. interfacial resistance, Brownian motion of particles, liquid layering at the solid-liquid interface and clustering of nanoparticles. In this work atomic scale simulation has been used to study possible mechanisms affecting the heat transfer characteristics of nanofluids. Molecular dynamics simulation for a single silica nanoparticle surrounded by water molecules has been performed. Periodic boundary condition has been used in all three directions. The effect of nanoparticle size and temperature of system on the thermal conductivity of nanofluids has been studied. It was found that as the size of nanoparticle decreases thermal conductivity of nanofluid increases. This is partially due to the fact that as the diameter of nanoparticle decreases from micrometer to nanometer its surface area to volume ratio increases by a factor of 103. Since heat transfer between the fluid and the nanoparticle takes place at the surface this enhanced surface area gives higher thermal conductivity for smaller particles. Thermal conductivity enhancement is also due to the accumulation of water molecules near the particle surface and the lattice vibration of the nanoparticle. The phonon transfer through the second layer allows the nanofluid thermal conductivity to increase by 23%-27% compared to the base fluid water for 2% concentration of nanosilica.
Show less
-
Date Issued
-
2006
-
Identifier
-
CFE0001278, ucf:46897
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFE0001278
-
-
Title
-
Homologous Pairing Through DNA Driven Harmonics - A Simulation Investigation.
-
Creator
-
Calloway, Richard, Proctor, Michael, Kincaid, John, Jaganathan, Balasubramanian, Gerber, Matthew, Chai, Xinqing, University of Central Florida
-
Abstract / Description
-
The objective of this research is to determine if a better understanding of the (")molecule of life("), deoxyribonucleic acid or DNA can be obtained through Molecular Dynamics (MD) modeling and simulation (M(&)S) using contemporary MD M(&)S. It is difficult to overstate the significance of the DNA molecule. The now-completed Human Genome Project stands out as the most significant testimony yet to the importance of understanding DNA. The Human Genome Project (HGP) enumerated many areas of...
Show moreThe objective of this research is to determine if a better understanding of the (")molecule of life("), deoxyribonucleic acid or DNA can be obtained through Molecular Dynamics (MD) modeling and simulation (M(&)S) using contemporary MD M(&)S. It is difficult to overstate the significance of the DNA molecule. The now-completed Human Genome Project stands out as the most significant testimony yet to the importance of understanding DNA. The Human Genome Project (HGP) enumerated many areas of application of genomic research including molecular medicine, energy sources, environmental applications, agriculture and livestock breeding to name just a few. (Science, 2008) In addition to the fact that DNA contains the informational blueprints for all life, it also exhibits other remarkable characteristics most of which are either poorly understood or remain complete mysteries. One of those completely mysterious characteristics is the ability of DNA molecules to spontaneously segregate with other DNA molecules of similar sequence. This ability has been observed for years in living organisms and is known as (")homologous pairing.(") It is completely reproducible in a laboratory and defies explanation. What is the underlying mechanism that facilitates long-range attraction between 2 double-helix DNA molecules containing similar nucleotide sequences? The fact that we cannot answer this question indicates we are missing a fundamental piece of information concerning the DNA bio-molecule. The research proposed herein investigated using the Nano-scale Molecular Dynamics NAMD (Phillips et al., 2005) simulator the following hypotheses:H(Simulate Observed Closure NULL) : = Current MD force field models when used to model DNA molecule segments, contain sufficient variable terms and parameters to describe and reproduce directed segregating movement (closure of the segments) as previously observed by the Imperial College team between two Phi X 174 DNA molecules. H(Resonance NULL) : = Current MD force field models when used to model DNA molecule segments in a condensed phased solvent contain sufficient variable terms and parameters to reproduce theorized molecular resonation in the form of frequency content found in water between the segments. H(Harmonized Resonance NULL) : = Current MD force field models of DNA molecule segments in a condensed phase solvent produce theorized molecular resonation in the form of frequency content above and beyond the expected normal frequency levels found in water between the segments. H(Sequence Relationship NULL): = The specific frequencies and amplitudes of the harmonized resonance postulated in H(Harmonized Resonance NULL) are a direct function of DNA nucleotide sequence. H(Resonance Causes Closure NULL) : = Interacting harmonized resonation produces an aggregate force between the 2 macro-molecule segments resulting in simulation of the same directed motion and segment closure as observed by the Imperial College team between two Phi X 174 DNA molecules. After nearly six months of molecular dynamic simulation for H(Simulate Observed Closure NULL) and H(Resonance Causes Closure NULL) no evidence of closure between two similar sequenced DNA segments was found. There exist several contributing factors that potentially affected this result that are described in detail in the Results section. Simulations investigating H( Resonance NULL), H(Harmonized Resonance NULL) and the emergent hypothesis H(Sequence Relationship NULL) on the other hand, revealed a rich selection of periodic pressure variation occurring in the solvent between simulated DNA molecules. About 20% of the power in Fourier coefficients returned by Fast Fourier Transforms performed on the pressure data was characterized as statistically significant and was located in less than 2% of the coefficients by count. This unexpected result occurred consistently in 5 different system configurations with considerable system-to-system variation in both frequency and magnitude. After careful analysis given the extent of our experiments the data was found to be in support of H( Resonance NULL), and H(Harmonized Resonance NULL) . Regarding the emergent hypothesis H(Sequence Relationship NULL), further analysis was done on the aggregate data set looking for correlation between nucleotide sequence and frequency/magnitude. Some of the results may be related to sequence but were insufficient to prove it. Overall the conflicting results were inconclusive so the hypothesis was neither accepted nor rejected. Of particular interest to future researchers it was noted that the computational simulations performed herein were NOT able to reproduce what we know actually happens in a laboratory environment. DNA segregation known to occur in-vitro during the Imperial College investigation did not occur in our simulation. Until this discrepancy is resolved MM simulation should not as yet be considered a suitable tool for further investigation of Homologous Chromosome Pairing. In Chapter 5 specific follow on research is described in priority of need addressing several new questions.
Show less
-
Date Issued
-
2011
-
Identifier
-
CFE0004472, ucf:49302
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFE0004472
-
-
Title
-
BIOGEOGRAPHY AND DIVERSIFICATION IN THE NEOTROPICS: TESTING MACROEVOLUTIONARY HYPOTHESES USING MOLECULAR PHYLOGENETIC DATA.
-
Creator
-
Daza Rojas, Juan Manuel, Parkinson, Christopher, University of Central Florida
-
Abstract / Description
-
Lineage diversification in the Neotropics is an interesting topic in evolutionary biology and one of the least understood. The complexity of the region precludes generalizations regarding the historical and evolutionary processes responsible for the observed high diversity. Here, I use molecular data to infer evolutionary relationships and test hypotheses of current taxonomy, species boundaries, speciation and biogeographic history in several lineages of Neotropical snakes. I comprehensively...
Show moreLineage diversification in the Neotropics is an interesting topic in evolutionary biology and one of the least understood. The complexity of the region precludes generalizations regarding the historical and evolutionary processes responsible for the observed high diversity. Here, I use molecular data to infer evolutionary relationships and test hypotheses of current taxonomy, species boundaries, speciation and biogeographic history in several lineages of Neotropical snakes. I comprehensively sampled a widely distributed Neotropical colubrid snake and Middle American pitvipers and combined my data with published sequences. Within the colubrid genus Leptodeira, mitochondrial and nuclear markers revealed a phylogeograhic structure that disagrees with the taxonomy based only on morphology. Instead, the phylogenetic structure corresponds to specific biogeographic regions within the Neotropics. Molecular evidence combined with explicit divergence time estimates reject the hypothesis that highland pitvipers in Middle America originated during the climatic changes during the Pleistocene. My data, instead, shows that pitviper diversification occurred mainly during the Miocene, a period of active orogenic activity. Using multiple lineages of Neotropical snakes in a single phylogenetic tree, I describe how the closure of the Isthmus of Panama generated several episodes of diversification as opposed to the Motagua-Polochic fault in Guatemala where a single vicariant event may have led to diversification of snakes with different ecological requirements. This finding has implications for future biogeographic studies in the region as explicit temporal information can be readily incorporated in molecular clock analyses. Bridging the gap between the traditional goals of historical biogeography (i.e., area relationships) with robust statistical methods, my research can be applied to multiple levels of the biological hierarchy (i.e., above species level), other regional systems and other sub-disciplines in biology such as medical research, evolutionary ecology, taxonomy and conservation.
Show less
-
Date Issued
-
2010
-
Identifier
-
CFE0003101, ucf:48328
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFE0003101
-
-
Title
-
Femtosecond Filament Interaction as a Probe for Molecular Alignment.
-
Creator
-
McKee, Erik, Richardson, Martin, Baudelet, Matthieu, Chang, Zenghu, University of Central Florida
-
Abstract / Description
-
Femtosecond laser filamentation is a highly nonlinear propagation mode. When a laser pulse propagates with a peak power exceeding a critical value Pcr (5 GW at 800 nm in air), the Kerr effect tends to collapse the beam until the intensity is high enough to ionize the medium, giving rise to plasma defocusing. A dynamic competition between these two effects takes place leaving a thin and weakly ionized plasma channel in the trail of the pulse. When an ultrafast laser pulse interacts with...
Show moreFemtosecond laser filamentation is a highly nonlinear propagation mode. When a laser pulse propagates with a peak power exceeding a critical value Pcr (5 GW at 800 nm in air), the Kerr effect tends to collapse the beam until the intensity is high enough to ionize the medium, giving rise to plasma defocusing. A dynamic competition between these two effects takes place leaving a thin and weakly ionized plasma channel in the trail of the pulse. When an ultrafast laser pulse interacts with molecules, it will align them, spinning them about their axis of polarization. As the quantum rotational wave packet relaxes, the molecules will experience periodic field-free alignment. Recent work has demonstrated the effect of molecular alignment on laser filamentation of ultra-short pulses. Revival of the molecular alignment can modify filamentation parameters as it can locally modify the refractive index and the ionization rate. In this thesis, we demonstrate with simulations and experiments that these changes in the filament parameters (collapse distance and filament plasma length) can be used to probe molecular alignment in CO2.
Show less
-
Date Issued
-
2013
-
Identifier
-
CFE0005033, ucf:50000
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFE0005033
-
-
Title
-
DEVELOPMENT OF A COMPACT BROADBAND OPTICAL PARAMETRIC OSCILLATOR FOR ULTRA-SENSITIVE MOLECULAR DETECTION.
-
Creator
-
Crystal, Sean O, Vodopyanov, Konstantin L., University of Central Florida
-
Abstract / Description
-
Every gas molecule has a unique absorption spectrum that can be captured using optical spectroscopy to identify an unknown sample's composition. Frequency combs systems can provide an extremely broad mid-infrared spectrum that is very useful for molecular detection. A degenerate optical parametric oscillator (OPO) was built to generate the down-converted and shifted frequency comb spectrum. This system utilizes an ultra-short pulse 1.56�m pump laser and a never before used orientation...
Show moreEvery gas molecule has a unique absorption spectrum that can be captured using optical spectroscopy to identify an unknown sample's composition. Frequency combs systems can provide an extremely broad mid-infrared spectrum that is very useful for molecular detection. A degenerate optical parametric oscillator (OPO) was built to generate the down-converted and shifted frequency comb spectrum. This system utilizes an ultra-short pulse 1.56�m pump laser and a never before used orientation patterned gallium-phosphide crystal. Periodically polled lithium niobate (PPLN), Gallium Arsenide (GaAs) and Gallium Phosphide are all crystals used to accomplish this task. GaP, in comparison to PPLN, has (i) a larger nonlinear coefficient, (ii) much deeper infrared transparency, and (iii) smaller group dispersion � to allow for achieving broad spectral coverage. GaP also has a larger band gap than GaAs; therefore it can still be pumped with a standard telecom C-band laser. An octave-wide spanning frequency comb system was achieved and the characterization of the system is presented. This system is specifically designed to be compact and portable for initial experimental testing in the applications of medical breath analysis and combustion gas investigation.
Show less
-
Date Issued
-
2017
-
Identifier
-
CFH2000274, ucf:45837
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFH2000274
-
-
Title
-
COARSE GRAINED MONTE CARLO SIMULATION OF THE SELF-ASSEMBLY OF THEHIV-1 CAPSID PROTEIN.
-
Creator
-
Weber, Jeffrey, Chen, Bo, University of Central Florida
-
Abstract / Description
-
In this study, a Monte Carlo simulation was designed to observe the self-assembly of the HIV-1 capsid protein. The simulation allowed a coarse grained model of the capsid protein with defined interaction sites to move freely in three dimensions using the Metropolis criterion. Observations were made as to which parameters affected the assembly the process. The ways in which the assembly were affected were also noted. It was found that proper dimerization of the capsid protein was necessary in...
Show moreIn this study, a Monte Carlo simulation was designed to observe the self-assembly of the HIV-1 capsid protein. The simulation allowed a coarse grained model of the capsid protein with defined interaction sites to move freely in three dimensions using the Metropolis criterion. Observations were made as to which parameters affected the assembly the process. The ways in which the assembly were affected were also noted. It was found that proper dimerization of the capsid protein was necessary in order for the lattice to form properly. It was also found that a strong trimeric interface could be responsible for double-layered assemblies. Further studies may be conducted by further varying of parameters or reworking the dynamics of the simulation. The possible causes of curvature within the assembly still need to be researched further.
Show less
-
Date Issued
-
2014
-
Identifier
-
CFH0004618, ucf:45316
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFH0004618
-
-
Title
-
SIMULATION STUDIES OF SELF-ASSEMBLY AND PHASE DIAGRAMOF AMPHIPHILIC MOLECULES.
-
Creator
-
Bourov, Geuorgui, Bhattacharya, Aniket, University of Central Florida
-
Abstract / Description
-
The aim of this dissertation is to investigate self-assembled structures and the phase diagram of amphiphilic molecules of diverse geometric shapes using a number of different computer simulation methods. The semi-realistic coarse-grained model, used extensively for simulation of polymers and surfactant molecules, is adopted in an off-lattice approach to study how the geometric structure of amphiphiles affects the aggregation properties. The results of simulations show that the model system...
Show moreThe aim of this dissertation is to investigate self-assembled structures and the phase diagram of amphiphilic molecules of diverse geometric shapes using a number of different computer simulation methods. The semi-realistic coarse-grained model, used extensively for simulation of polymers and surfactant molecules, is adopted in an off-lattice approach to study how the geometric structure of amphiphiles affects the aggregation properties. The results of simulations show that the model system behavior is consistent with theoretical predictions, experiments and lattice simulation models. We demonstrate that by modifying the geometry of the molecules, self-assembled aggregates are altered in a way close to theoretical predictions. In several two and three dimensional off-lattice Brownian Dynamics simulations, the influence of the shape of the amphiphilic molecules on the size and form of the aggregates is studied systematically. Model phospholipid molecules, with two hydrophobic chains connected to one hydrophilic head group, are simulated and the formation of stable bilayers is observed. In addition, (practically very important) mixtures of amphiphiles with diverse structures are studied under different mixing ratios and molecular structures. We find that in several systems, with Poisson distributed chain lengths, the effect on the aggregation distribution is negligible compared to that of the pure amphiphilic system with the mean length of the Poisson distribution. The phase diagrams of different amphiphilic molecular structures are investigated in separate simulations by employing the Gibbs Ensemble Monte Carlo method with an implemented configurational-bias technique. The computer simulations of the above mentioned amphiphilic systems are done in an area where physics, biology and chemistry are closely connected and advances in applications require the use of new theoretical, experimental and simulation methods for a better understanding of their self-assembling properties. Obtained simulation results demonstrate the connection between the structure of amphiphilic molecules and the properties of their thermodynamically stable aggregates and thus build a foundation for many applications of the remarkable phenomena of amphiphilic self-assembly in the area of nanotechnology.
Show less
-
Date Issued
-
2005
-
Identifier
-
CFE0000695, ucf:46491
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFE0000695
-
-
Title
-
SPLIT DEOXYRIBOZYME PROBE FOR EFFICIENT DETECTION OF HIGHLY STRUCTURED RNA TARGETS.
-
Creator
-
Solarez, Sheila Raquel, Gerasimova, Yulia, De Bekker, Charissa, University of Central Florida
-
Abstract / Description
-
Transfer RNAs (tRNAs) are known for their role as adaptors during translation of the genetic information and as regulators for gene expression; uncharged tRNAs regulate global gene expression in response to changes in amino acid pools in the cell. Aminoacylated tRNAs play a role in non-ribosomal peptide bond formation, post-translational protein labeling, modification of phospholipids in the cell membrane, and antibiotic biosynthesis.[1] tRNAs have a highly stable structure that can present a...
Show moreTransfer RNAs (tRNAs) are known for their role as adaptors during translation of the genetic information and as regulators for gene expression; uncharged tRNAs regulate global gene expression in response to changes in amino acid pools in the cell. Aminoacylated tRNAs play a role in non-ribosomal peptide bond formation, post-translational protein labeling, modification of phospholipids in the cell membrane, and antibiotic biosynthesis.[1] tRNAs have a highly stable structure that can present a challenge for their detection using conventional techniques.[2] To enable signal amplification and lower detection limits, a split probe - split deoxyribozyme (sDz or BiDz) probe, which uses a double-labeled fluorogenic substrate as a reporter - has been introduced. In this project we developed an assay based on sDz probe to detect yeast tRNA[Phe] as a proof-of-principle highly structured target. An sDz probe was designed specific to tRNA[phe] that could efficiently unwind stable secondary and tertiary structure of the target RNA thereby providing an efficient tool for tRNA detection.[3] The efficiency of the developed sDz probe was compared with a currently used state-of-the-art hybridization probe - molecular beacon probe. The results obtained in the project further demonstrate the power of sDz probes for the detection of highly structured RNA analytes. The split probes show signal amplification capabilities in detection of structured analytes, which will benefit diagnostics, fundamental molecular biology research and therapeutic fields.
Show less
-
Date Issued
-
2018
-
Identifier
-
CFH2000311, ucf:45728
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFH2000311
-
-
Title
-
THE ROLE OF INTESTINAL SWEET TASTE RECEPTORS (STRS) IN THE REGULATION OF GLUCOSE ABSORPTION: EFFECTS OF SHORT TERM HIGH SUCROSE DIET (HSD).
-
Creator
-
Hussain, Tania, Borgon, Robert, University of Central Florida
-
Abstract / Description
-
Sweet taste receptors are primarily found in the oral cavity of the mammalian species. However, recent studies have shown that sweet taste receptors can be found in extraoral tissues such as the pancreas, intestines, and adipose tissue. Our lab has previously found that sweet taste receptors are down-regulated on the pancreas in the presence of high plasma glucose levels. In order to assess the possibility that sweet taste receptors respond to high levels of glucose by suppressing its...
Show moreSweet taste receptors are primarily found in the oral cavity of the mammalian species. However, recent studies have shown that sweet taste receptors can be found in extraoral tissues such as the pancreas, intestines, and adipose tissue. Our lab has previously found that sweet taste receptors are down-regulated on the pancreas in the presence of high plasma glucose levels. In order to assess the possibility that sweet taste receptors respond to high levels of glucose by suppressing its expression, we wanted to see if they reacted similarly on the intestines. We found that intestinal sweet taste receptors are down regulated in the presence of a 24 hour high sucrose diet (60% sucrose), and a 7 day high sucrose diet in both wild type (WT) mice on the high sucrose diet, and T1R2-KO (lacking sweet taste receptors) mice. We also examined their glucose excursion levels, and found that these mice are lacking a normal response to dietary glucose via an oral glucose tolerance test (OGTT). This led us to conclude that the mice lacking sweet taste receptor expression exhibit abnormal glucose absorption, possibly indicating that sweet taste receptors regulate glucose absorption in the intestines.
Show less
-
Date Issued
-
2014
-
Identifier
-
CFH0004686, ucf:45236
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFH0004686
-
-
Title
-
CONTROLLED DEPOSITION OF MAGNETIC MOLECULES AND NANOPARTICLES ON ATOMICALLY FLAT GOLD SURFACES.
-
Creator
-
Haque, Md. Firoze, del Barco, Enrique, University of Central Florida
-
Abstract / Description
-
In this thesis I am presenting a detailed study to optimize the deposition of magnetic molecules and gold nanoparticles in atomically flat surfaces by self-assembling them from solution. Epitaxially grown and atomically flat gold surface on mica is used as substrate for this study. These surfaces have roughness of the order one tenth of a nanometer and are perfect to image molecules and nanoparticles in the 1-10 nanometers range. The purpose of these studies is to find the suitable parameters...
Show moreIn this thesis I am presenting a detailed study to optimize the deposition of magnetic molecules and gold nanoparticles in atomically flat surfaces by self-assembling them from solution. Epitaxially grown and atomically flat gold surface on mica is used as substrate for this study. These surfaces have roughness of the order one tenth of a nanometer and are perfect to image molecules and nanoparticles in the 1-10 nanometers range. The purpose of these studies is to find the suitable parameters and conditions necessary to deposit a monolayer of nano-substance on chips containing gold nanowires which will eventually be used to form single electron transistors by electromigration breaking of the nanowire. Maximization of the covered surface area is crucial to optimize the yield of finding a molecule/nanoparticle near the gap formed in the nanowire after electromigration breaking. Coverage of the surface by molecules/nanoparticles mainly depends on the deposition time and concentration of the solution used for the self-assembly. Deposition of the samples under study was done for different solution concentrations and deposition times until a self-assembly monolayer covering most of the surface area is obtained. Imaging of the surfaces after deposition was done by tapping-mode AFM. Analysis of the AFM images was performed and deposition parameters (i.e. coverage or molecule/particle size distribution) were obtained. The subjects of this investigation were a molecular polyoxometalate, a single-molecule magnet and functionalized gold nanoparticles. The obtained results agree with the structure of each of the studied systems. Using the optimized deposition parameters found in this investigation, single-electron transport measurements have been carried out. Preliminary results indicate the right choice of the deposition parameters.
Show less
-
Date Issued
-
2008
-
Identifier
-
CFE0002338, ucf:47795
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFE0002338
-
-
Title
-
Spin and Charge Transport in Graphene Based Devices.
-
Creator
-
Anguera Antonana, Marta, Del Barco, Enrique, Peale, Robert, Bhattacharya, Aniket, Schoenfeld, Winston, University of Central Florida
-
Abstract / Description
-
The present dissertation is comprehended in two main parts. The first part is focused on understanding the mechanisms behind spin current to charge current interconversion (i.e. the spin Hall angle), where the spin current is generated by means of spin pumping. The measurement of a positive spin Hall angle of magnitude 0.004 in Uranium is reported in Chapter 2. These results support the idea that the electronic configuration may be at least as important as the atomic number in governing spin...
Show moreThe present dissertation is comprehended in two main parts. The first part is focused on understanding the mechanisms behind spin current to charge current interconversion (i.e. the spin Hall angle), where the spin current is generated by means of spin pumping. The measurement of a positive spin Hall angle of magnitude 0.004 in Uranium is reported in Chapter 2. These results support the idea that the electronic configuration may be at least as important as the atomic number in governing spin Hall effects. In Chapter 3, the design of a spintronics device designed to interconvert charge and spin currents in CVD graphene is presented. The second part of the thesis is centered in the study of transport through single molecules with the use of three-terminal devices. The first evidence of a molecular double quantum dot is detailed in Chapter 5. The conclusions are supported by self-assembled monolayers (SAMs) and single-electron transistors (SETs) measurements. Using gold electrodes for SETs measurements has its disadvantages, two of the main ones being: the junctions are not stable at room temperature and it does not allow for transport measurements in the presence of light. Graphene electrodes, on the other hand, have been reported to be stable at temperatures above room temperature and have no absorption in the visible range. Along those lines, the development of a multilayer graphene-based SET is reported in Chapter 6. Finally, a new technique, based on CVD graphene transistors, that will allow three-terminal measurements on an STM is described in Chapter 7.
Show less
-
Date Issued
-
2017
-
Identifier
-
CFE0006715, ucf:51897
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFE0006715
-
-
Title
-
Allelic characterization and novel functions of the outer membrane porin U in Vibrio cholerae.
-
Creator
-
Sakib, Sk Nazmus, Almagro-Moreno, Salvador, Moore, Sean, Roy, Herve, University of Central Florida
-
Abstract / Description
-
Vibrio cholerae is the etiological agent of the severe diarrheal disease cholera. The bacterium is a natural inhabitant of brackish and estuarine waters . To date, only a subset of V. cholerae strains, those belonging to the pandemic group (PG), can cause cholera in humans while the rest (environmental group, EG) cannot cause the disease. Recently, we discovered that V. cholerae PG contains allelic variations in core genes that confer preadaptation to virulence, which we termed Virulence...
Show moreVibrio cholerae is the etiological agent of the severe diarrheal disease cholera. The bacterium is a natural inhabitant of brackish and estuarine waters . To date, only a subset of V. cholerae strains, those belonging to the pandemic group (PG), can cause cholera in humans while the rest (environmental group, EG) cannot cause the disease. Recently, we discovered that V. cholerae PG contains allelic variations in core genes that confer preadaptation to virulence, which we termed Virulence Adaptive Polymorphisms (VAPs). We identified nine core genes that encode potential VAPs, one of which encodes the outer membrane porin U (OmpU). OmpU provides tolerance to bile and acidic pH, resistance to antimicrobials and facilitates biofilm formation. In this study, several alleles of ompU were analyzed to determine whether these VAPs encode different functional properties. We performed multiple phenotypic assays and observed increased survival for strains encoding the PG-like alleles in the presence of bile, organic acid, anionic detergents and the antimicrobial peptide P2. On the other hand, EG-like alleles only showed increased biofilm formation. Interestingly, tests for motility and tolerance of inorganic acid, polymyxin B and protamine sulphate showed no differences in survival for strains encoding either alleles indicating that some of the properties conferred by OmpU are allelic independent. We have also discovered that V. cholerae OmpU shows resistance against Rifamycin, EDTA and Trifluoperazine and interestingly, Rifamycin has been found to be PG-allele dependent. Our findings provide further evidence that genetic variations in core genes lead to the emergence of virulence adaptive traits in pathogenic V. cholerae and can be extrapolated to other bacterial pathogens.
Show less
-
Date Issued
-
2019
-
Identifier
-
CFE0007720, ucf:52420
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFE0007720
-
-
Title
-
LOW COST PRODUCTION OF PROINSULIN IN TOBACCO AND LETTUCE CHLOROPLASTS FOR INJECTABLE OR ORAL DELIVERY OF FUNCTIONAL INSULIN AND C-PEPTIDE.
-
Creator
-
Burberry, Diane, Daniell, Henry, University of Central Florida
-
Abstract / Description
-
Current treatment for type I diabetes includes delivery of insulin via injection or pump, which is highly invasive and expensive. The production of chloroplast-derived proinsulin should reduce cost and facilitate oral delivery. Therefore, tobacco and lettuce chloroplasts were transformed with the cholera toxin B subunit fused with human proinsulin (A, B, and C peptides) containing three furin cleavage sites (CTB-PFx3). Transplastomic lines were confirmed for site-specific integration of...
Show moreCurrent treatment for type I diabetes includes delivery of insulin via injection or pump, which is highly invasive and expensive. The production of chloroplast-derived proinsulin should reduce cost and facilitate oral delivery. Therefore, tobacco and lettuce chloroplasts were transformed with the cholera toxin B subunit fused with human proinsulin (A, B, and C peptides) containing three furin cleavage sites (CTB-PFx3). Transplastomic lines were confirmed for site-specific integration of transgene and homoplasmy. Old tobacco leaves accumulated proinsulin up to 47% of total leaf protein (TLP). Old lettuce leaves accumulated proinsulin up to 53% TLP. Accumulation was so stable that up to ~40% proinsulin in TLP was observed even in senescent and dried lettuce leaves, facilitating their processing and storage in the field. Based on the yield of only monomers and dimers of proinsulin (3 mg/g leaf, a significant underestimation), with a 50% loss of protein during the purification process, one acre of tobacco could yield up to 20 million daily doses of insulin per year. Proinsulin from tobacco leaves was purified up to 98% using metal affinity chromatography without any His-tag. Furin protease cleaved insulin peptides in vitro. Oral delivery of unprocessed proinsulin bioencapsulated in plant cells or injectable delivery into mice showed reduction in blood glucose levels similar to processed commercial insulin. C-peptide should aid in longterm treatment of diabetic complications including stimulation of nerve and renal functions. Hyper-expression of functional proinsulin and exceptional stability in dehydrated leaves offer a low cost platform for oral and injectable delivery of cleavable proinsulin.
Show less
-
Date Issued
-
2010
-
Identifier
-
CFE0003257, ucf:48554
-
Format
-
Document (PDF)
-
PURL
-
http://purl.flvc.org/ucf/fd/CFE0003257
Pages