Illinois LS-AMP

THE 9TH ANNUAL ILLINOIS STOKES ALLIANCE FOR MINORITY PARTICIPATION STUDENT RESEARCH CONFERENCE
Glenview, Illinois, October 6-7, 2006

ORAL PRESENTATIONS

HETEROGENEOUS TRANSCRIPTION START SITES IN ALFALFA (MEDICAGO SATIVA L.) ROOTCAR1 PROMOTER  IN RESPONSE TO COLD STRESS
Angenee Milton*, S. M. Cunningham, J. J. Volenec, J. A.  Gana
Department of Biological Sciences, Chicago State University, Chicago, Illinois 60628
Department of Agronomy, Purdue University, West Lafayette, Indiana

Angenee Milton
Angenee is an alumna of the CSU MBRS-RISE Program.  She is currently a graduate studentin biology at the University of Illinois at Chicago.

 

 

Plants respond to cold stress by expressing several genes that allow for growth adjustments at low temperatures. The regulation of many of these cold-inducible genes occurs at the transcription level.  Transcripts for one such gene, RootCAR1, accumulate differentially in fall-dormant, freeze-tolerant alfalfa cultivars than in non-fall dormant and freeze-susceptible cultivars during cold acclimation.  RootCAR1 contains two TATA-box elements. Often, the occurrence of multiple TATA elements directs alternate utilization of transcription initiation sites from a single gene.  Our hypothesis is that the dual TATA in the RootCAR1 promoter allows for alternate use of transcription initiation sites as alfalfa responds to cold stress in a tissue-specific manner.  To test this hypothesis, three-week-old alfalfa seedlings were exposed to cold stress (4oC) for 24 hours.  In addition, field-grown plants were exposed to natural cold acclimation conditions in autumn. Total RNA was isolated from roots and leaves and subjected to RT-PCR and RNA ligase-mediated 5’RACE (RLM-5’RACE) analyses. Results of 5’RLM RACE revealed two bands on agarose gels, indicating two transcripts from RootCAR1.  Sequence analysis suggests that both transcripts are directed from the same TATA element closest to the ATG start codon, but differ in their 5’UTR regions by insertions, deletions, and single nucleotide polymorphisms.  The transcription start site was heterogeneous initiating from three different nucleotides within a seven-nucleotide stretch. Our results demonstrated that only the TATA box closer to the translation initiation codon in RootCAR1 is functional in response to cold stress.

PREPARATION OF RUTHENIUM BIDENTATE SCHIFF-BASE COMPLEXES VIA MICROWAVE IRRADIATION
Pablo E. Guzman and LeRoy Jones II
Department of Chemistry & Physics, Chicago State University, Chicago, Illinois 60426

Pablo Guzman presenting

Pablo Guzman presenting (close up)

With the introduction of more efficient catalyst systems, ring-closing metathesis has emerged as a powerful and efficient method for carbon-carbon bond formation enabling the synthesis of small to macrocyclic carbocycles and heterocycles.  The development of economically safe Ruthenium-based olefin metathesis catalysts coordinated with bidentate Schiff-base ligands for enantioselective and stereoselective applications, however, remains to be accomplished.  Recently a novel series of Schiff base substituted ruthenium carbon complexes were prepared by the treatment of RuCl2(=CHPh)(PCy3)2 with a variety of Schiff-base ligand salts that could potentially support chiral substituents.  These complexes showed high metathesis activity in polar protic solvents as well as in commonly used organic solvents such as dichloromethane or benzene.  Although the complexes could be prepared in three steps in moderate to excellent yields, the last step required the use of the Schiff-base ligands in the form of their thallium salts.  It was reported that various salts were tested, including sodium, lithium, and potassium, but the thallium salts, albeit toxic, proved to be the most efficient and were consequently used in all the substitution reactions.  Recently, this laboratory has focused on the relevance of microwave irradiation in organometallic synthesis, namely to develop late transition metal complexes.  The aim of this study is to perform the substitution reaction with less toxic salts of Schiff-base ligands using a microwave reactor.

The commercially unavailable Schiff-base was prepared via condensation of nitro-substituted salicylaldehyde with an aromatic amine in ethyl alcohol with stirring at 80?C for 2 hrs.  Upon cooling to 0?C, a yellow solid precipitated from the reaction mixture.  The solid was filtered, washed with cold ethanol, and dried in vacuo to afford the desired Schiff-base ligand, 83 %yield.  To a cold solution of salicylaldimine ligand in THF, 5 mL of 1M sodium hydride was added drop wise.  Immediately after the addition, a yellow solid formed and the reaction mixture was allowed to warm to room temperature with stirring.  Filtration of the solid using standard Schlenk techniques afforded the sodium salt in quantitative yields.  To a solution of the sodium analog Schiff-base in THF-d8, Grubbs catalyst, also dissolved in THF-d8, was added drop wise and thouroghly mixed.  The solution was than subjected to microwave irradiation.  1H NMR showed the desired product carbene as a doublet at 19.78 ppm.

In conclusion, this methodology will provide a safer route to prepare ruthenium bidentate application Schiff-base catalysts for olefin metathesis reactions.  Moreover, the Schiff-base catalyst can be modified to possess chiral character, which in turn, opens the possibility for asymmetric catalysis in medicinal chemistry.

AN IMPROVED ALGORITHM FOR SEGREGATING LARGE GEOSPATIAL DATA
Kara E. Scott* and Tonny J. Oyana,
Department of Geography and Environmental Resources, Southern Illinois University at Carbondale, Illinois 62901

Kara Scott presenting
*Kara Scott is an alumna of the CSU MBRS-RISE Program.  She is currently a graduate student at SIU.

This study investigates an improved K-means clustering algorithm for segregating large geospatial data. Although the conventional K-means method is sufficient for datasets with minimal data, it does not perform well and, therefore yields poor accuracy for high-volume datasets. Clustering methods are one of the most important components in data classification, visualization, and mining high-volume datasets. Needless to say, the importance of strengthening these methods in order to perform such functions is substantial. The primary aim of this study is to explore by integrating two methods that were individually designed to increase the overall performance of K-means clustering: Mashor's updating method and the Davies-Bouldin validity index. Mashor’s method generates equally active cluster centers at a faster convergence rate due to 1) minimize the fluctuation of clusters; 2) efficient service of larger datasets; and 3) adequate analysis of datasets with large dispersion. The Davies-Bouldin validity index is an algorithm used to measure partitioning quality following the k-means clustering procedure. We use real georeferenced biomedical data to test these two methods. Our results for the fast and efficient clustering method confirm our assumption that Mashor’s method provides a faster and more efficient clustering result than DBI. The findings of this study are vital for the relatively new and expanding field of geospatial data management.

POSTER PRESENTATIONS

RECOMBINANT BAX PREFERENTIALLY BINDS TO SUV CONTAINING CARDIOLIPIN RESULTING IN A CONFORMATIONAL CHANGE
Michonne C. Berry and Juanita C. Sharpe
Department of Biological Sciences, Chicago State University, Chicago, Illinois 60628

 

Apoptosis is the mechanism used to maintain proper structure and function in many organisms, by eliminating cells that are no longer needed in a tissue, or cells that have reached senescence or are damaged.   The Bcl-2 family of proteins regulates the intrinsic pathway of apoptosis.  Bax, a proapoptotic member of the Bcl-2 family, is dispersed as a monomer throughout the cytosol.  When a cell receives a signal to die, Bax relocates to the mitochondria and binds to the outer mitochondrial membrane.  This ultimately results in the release of the mitochondria’s inter-membrane space contents and the activation of cell death.  During apoptosis, remodeling of the mitochondrial lipid bilayer may be necessary to achieve the release of apoptogenic factors from the mitochondrial inner membrane space. Bax has been shown to cause the translocation of the mitochondrial specific lipid, cardiolipin, from the inner mitochondrial membrane to the outer mitochondrial membrane during apoptosis (Epand et al., 2003). It is suspected that the Bax – cardiolipin interaction facilitates the formation of pores in the mitochondria to allow the release of inter-membrane space proteins. We propose that a specific binding occurs between cardiolipin Bax resulting in a conformational change that is induced by the tight insertion of Bax into cardiolipin-containing vesicles.  We suspect that this binding results in Bax obtaining a membrane-active conformation.  Our goals are to establish the specific binding, binding strength, binding specificity and conformation of rBax in small unilamellar vesicles via immunoprecipitation, high-speed centrifugation, chemical extraction and western blotting.  Our goals are to compare the binding of Bax to cardiolipin-containing vesicles to vesicles with either negative charge or vesicles without charge to demonstrate the strength and specificity of the interaction between Bax and cardiolipin and to monitor conformational changes.  These results will help to establish a structural role for the Bax-cardiolipin interaction.

SYNTHESIS AND EVALUATION OF AUTONOMOUS HEALING AGENTS FOR BONE CEMENT
Sonya Blackman, LeRoy Jones II, Patrick Biggs and  Gladius Lewis
Department of Chemistry and Physics, Chicago State University, Chicago, Illinois, 60628 and the Department of Mechanical Engineering, The University of Memphis, Memphis, Tennessee

Sonya Blackman

In cemented arthroplasty, an acrylic bone cement mantle is used to secure the prosthesis to contiguous bone.  The mantle often experiences cracks and fatigue fracture – due to the propagation of air trapped within, blood inclusion, etc. – which can lead to aseptic loosening of the prosthesis.  Our goal is to synthesize and characterize an autonomous, or self-healing system, which would heal these cracks and fractures, and therefore, extend the lifetime of the bone cement while maintaining its structural and functional integrity.  In the bone cement mantle, an autonomic healing agent is contained within a microcapsule, which when breached, is released and travels through the crack by capillary action.  Also, throughout the mantle is a catalyst, which polymerizes the agent upon contact.  We hypothesize that the incorporation of autonomic healing agents into a bone cement mantle will markedly increase the durability and longevity of the bone cement mantle, while significantly decreasing the acceleration of cracks through it.

Phase I of our project is to incorporate an autonomous system into a bone cement mantle and subject it to fracture toughness, fatigue life, and fatigue crack propagation rate behavior tests.  The self-healing cements were synthesized by incorporating Grubbs’ catalyst, RuCl2(=CHPh)(PCy3)2, and urea-formaldehyde microcapsules containing the healing agent dicyclopentadiene (DCPD) into Cemex® XL, an acrylic bone cement that is commonly used in total joint replacements.  We prepared three variant cement formulations by doping Cemex® XL with different amounts of Grubbs’ catalyst and the DCPD microcapsules.  The plane-strain fracture toughness of each of the formulations was determined per ASTM D 5045, using compact tension test specimens, at a crosshead displacement rate of 10 mm/min.  The tests were conducted 4.5 days after the fabrication of the specimens, with the specimens having been stored in ambient laboratory air conditions.  The preliminary fracture toughness results were promising in that they are consistent with the trends reported in a previous paper using epoxy resins.  Also, in the present tests, the control specimens fractured in a brittle way, while the healed specimens displayed a high amount of ductility.  We are currently working to further define and elucidate the autonomous cements and identify other catalysts and healing agents that are more compatible with the human body.

THE APPLICATION OF MICROWAVE ENHANCED CHEMSITRY TO GOLD NANOPARTICLE SYNTHESIS
Tiffany Brown, Brian Leverson, Barbara Maali, Ron Glowinski, and Robert Richter
Department of Chemistry and Physics, Chicago State University, Chicago, Illinois 60628

Tiffany Brown

Brian Leverson

Gold nanoparticles have received considerable attention in recent years due to their unique physical properties, chemical reactivity, and potential applications as optical biosensors and gene delivery devices.  Since the uniformity of nanoparticles in solution determine their bulk properties, better methods of preparation that control their number, particle size, and shape are desirable.  The use of microwave energy to drive chemical reactions has become increasingly popular among synthetic chemists.  The fast and uniform heating that microwave energy offers makes it an ideal candidate for nanoparticle synthesis.  The objective of this study was to determine if microwave enhanced chemistry techniques can be used to improve the synthesis of gold nanoparticles and their thiol-based functionalizing agents. The effects of solvent, concentration of reactants, heating rate, reaction temperature, microwave energy input were investigated.  We have found that the reaction temperature plays a role in the size and shape gold nanoparticles.  We have also observed that the choice of solvent for the thiol based functionalizing agents determines whether the reaction proceeds via the traditional two-step mechanism or a microwave enhanced one-step mechanism. 

HIRANO BODIES ARE FOUND IN THE CYTOPLASMIC BRIDGE BETWEEN DIVIDING DICTYSTELIUM CELLS
Vashati Butler, Marsha Myrthil,and Andrew Maselli
Department of Biological Sciences, Chicago State University, Chicago, Illinois 60628

 

Neurodegenerative diseases such as Alzheimer’s and Pick’s disease have altered the lives of many people.  Previous research and postmortem analysis showed that inclusions of protein are present in the brain tissue of affected individuals.  The protein aggregates of interest to our research are the Hirano bodies. Hirano bodies are paracrystalline cytoplasmic inclusions that contain actin filaments and actin-associated proteins.  Our lab is working to establish Dictyostelium as a live cell model system to study the dynamics of Hirano body formation.  We are able to initiate Hirano body formation by expression of truncated form of a native actin binding protein.  One of the key questions is: What is the fate of the Hirano bodies once they are formed?  By using a GFP (green fluorescent protein) labeled form of the truncated 34kDa actin binding protein, we can track the location of the Hirano bodies in cells.  Our results show that Hirano bodies are present in the cytoplasmic bridges between dividing cells.  This suggests that Hirano bodies maybe lost during cell division.  After four days in culture, a substantial number of released Hirano bodies can be observed in the media.  The population of adhered cells in the same culture contained a consistent proportion of cells with Hirano bodies.

DETERMINATION OF FORCEFIELD PARAMETERS TO EVALUATE THE BINDING OF PORPHYRIN STRUCTURES TO C-TYPE CYTOCHROME ARCHITECTURES
Adrienne Eastland, Dr. Kristy L. Mardis, and David Tiede
Department of Chemistry and Physics, Chicago State University, Chicago, Illinois 60628
Argonne National Laboratory, Argonne, Illinois 60439

Adrienne Eastland

The binding of porphyrin-like molecules to the surface of c-type cytochrome  proteins allows the initiation of electron transport.  In order to develop biomimetic photosynthetic devices, the initiation step must be tuned by the choice of substituents on the porphyrin molecules.  Computational docking studies combined with experimental fluorescence studies allow the evaluation of  the effects of substituent changes on electron transport rates. The aim of this work is to develop a scoring function that is fast enough to be successfully applied to the prediction of the binding energy of a c-type cytochrome to a porphyrin-like ligand. Docking studies depend heavily on the scoring function employed.  By using ab initio calculations at the Hartree Fock//6-31G* level, bond, angle, and dihedral parameters for the CHARMM scoring function were developed for a series of small molecules, representative of functional groups found in organic and biochemical systems.  Upon parameterization, the dihedral force constant, k?, for the CA-CC-OC-OC dihedral in carboxybenzene was determined to be 3.66 kcal/mol/degree with n = 2 (n is the multiplicity of the function). For naphthalene dicarboxylate k? = 1.16 kcal/mol/degree with n = 4. The magnitudes of the k? values are in good agreement with existing CHARMM forcefield parameters. Furthermore, these values reproduce the quantum mechanical energy profiles as a function of angle with R2 values of 0.97 and 0.94 for the carboxybenzene and naphthalene dicarboxylate molecules, respectively.

MUTAGENESIS OF BAX TO DETERMINE THE REGION RESPONSIBLE FOR CARDIOLIPIN BINDING
Edgar L. Glover and Juanita C. Sharpe
Department of Biological Sciences, Chicago State University, Chicago, Illinois 60628

 

Apoptosis is a mechanism used to control the proliferation of unnecessary cells.  Unnecessary cells may result from the overpopulation of normal cells or from damaged or mutated cells that can potential be fatal to the body.  Apoptosis directly contributes to the, regulation, development, and homeostasis of all tissues that consists of cells that are constantly undergoing mitosis.  The process involved in programmed cell death consists of pathways involving proteins that promote apoptosis.  One of the most important of these proteins is Bax.  Bax is able to bind to the lipid, cardiolipin, which is found almost exclusively at the mitochondrial membrane.  The binding between Bax and cardiolipin may cause the release of the electron carrier, cytochrome-c, from the mitochondrial inter-membrane space, which is crucial for the activation of the apoptotic pathway.  Our laboratory is currently investigating the interaction between Bax and cardiolipin.  We believe that cardiolipin binding to Bax occurs at the Bcl-2 homology domain region three (BH3) of Bax and this binding causes the formation of pores at the mitochondrial membrane which allow the release of cytochrome-c into the cytosol.  To investigate if the BH3 region is responsible for cardiolipin binding, we have mutated the cluster of positively charged amino acids in the BH3 region using site directed mutagenesis. We have replaced positively charged lysines with uncharged alanines in order to study the effects that these mutations have on Bax binding to cardiolipin.  These results will allow us to establish the region of Bax responsible for the Bax-cardiolipin interaction.

DESIGN AND SYNTHESIS OF NON-METALLOCENE CATALYSTS FOR BIOMEDICAL APPLICATIONS
Tyvette Hilliard and LeRoy Jones II
Department of Chemistry and Physics, Chicago State University, Chicago, Illinois 60628

Tyvette Hilliard

Recently, a novel self-healing polymethyl methacrylate (PMMA) composite was designed and synthesized.  The composite consists of a PMMA, the primary component of acrylic bone cement, matrix that contain microcapsules loaded with dicyclopentadiene (healing agent) and particles of an olefin metathesis catalyst (initiator).  The healing agent in the microcapsule shell, when breached, is released and travels through the crack by capillary action.  Polymerization is triggered when the healing agent contacts the catalyst, sealing the crack closed.  Although the mean fracture toughness results of the aforesaid composites were promising, in that they were consistent with the trends reported in an existing reference, the need still exist to develop biocompatible catalyst and monomer chemistries for self-healing acrylic bone cement composites.  We aim to prepare and study new polymerization catalysts using nontoxic metals for methacrylic monomers.   

Over the past decade, several metallocene and non-metallocene catalysts have been reported to efficiently initiate the controlled homopolymerization of methacrylic monomers, particularly methyl methacrylate (MMA).  Metallocene-initiated MMA polymerizations are particularly attractive since the biocompatibility of residual MMA in acrylic bone cements have been reported.  Furthermore, this approach would introduce fewer compounds to the self-healing bone cement composition.  We have designed a novel iron (Fe) non-metallocene complex that could potentially be used as a catalyst in self-healing bone cement composites.  The synthesis involves the condensation of commercially available 2-bromobenzaldehyde with 2,6-diisopropylamine.  It was envisioned that the coupling of the resulting aryl bromide with lithium dicyclopentadienide (LiCp) could be accomplished using Negishi’s conditions, and that treatment of the coupled product with base followed by iron(II) chloride would yield our desired Fe complex.  We found that the imination of the aldehyde with the amine went very well.  However, several attempts to couple the imine with LiCp using various methods have failed.  As a result, we are currently conducting a series of model studies to determine the methodology to accomplish the desired coupling, which will enable us to prepare our desired Fe-based polymerization catalyst for methacrylic monomers.

Once we have developed biocompatible chemistries for self-healing PMMA composites, our work will have enormous positive implications for the use of acrylic bone cement to anchor endoprostheses, especially, hip and knee implants.  These benefits are very likely to translate to substantial improvements in patient satisfaction and healthcare costs.

CELLULAR LOCALIZATION OF b-AMYLASE IN BARK TISSUES OF ALFALFA TAPROOTS
Pamela Ihonor*, Emlah Yosimbom*, Denise J. Patrick and Joyce Ache Gana
Department of Biological Sciences, Chicago State University, Chicago, Illinois 60628


Pamela Ihonor
*Pamela Ihonor is an international student working in Dr Gana’s SCORE research lab. 

Emlah Yosimbom
Emlah Yosimbom was also an international student in a SCORE lab and is currently a graduate student at Ohio State University.

Alfalfa accumulates large quantities of starch in its taproots, which is degraded upon exposure to defoliation stress. Starch degradation pathways in alfalfa taproots are not well characterized. b-amylase is an enzyme that breaks down starch to maltose moieties. The role of b-amylase as a starch hydrolase in alfalfa roots is unclear because of its unusual kinetics of accumulation and disappearance mirroring that of starch following defoliation. Knowledge of the cellular location of b-amylase may shed light of its function in alfalfa roots.  Our objective therefore was to determine the cellular localization of b-amylase in cells of the bark tissues in alfalfa roots during periods of starch decline. Alfalfa cv 5454 was grown to flowering; one half of the plants was defoliated and compared to the control undefoliated plants.  Root sections were obtained from both defoliated and control plants 12 days after defoliation and analyzed by transmission electron microscopy for any discernable amyloplast structural alterations. For immunolocalization, sections were cross-reacted with polyclonal antibody to sweet potato β-amylase, and 10nm gold conjugated goat anti-rabbit IgG secondary antibody. Gold particles were detected by transmission electron microscopy. Defoliated alfalfa exhibited altered amyloplast structure. Further, most of the gold particles were localized to the cytoplasm of defoliated plants. The results obtained reveal that in the course of starch degradation, amyloplast structure is altered so that starch is exposed to the isoform of b-amylase located in the cytoplasm.

FLUORESCENT SPECTROSCOPIC ANALYSIS OF THE INTERACTION BETWEEN BAX AND SMALL UNILAMELLAR VESICLES  TO MODEL THE INTERACTION BETWEEN BAX  AND THE MITOCHONDRIA DURING APOPTOSIS
Nicole M. Jones* and Juanita C. Sharpe
Department of Biological Sciences, Chicago State University, Chicago Illinois 60628

*Nicole Jones is an MBRS-RISE alumna.  She is currently a graduate student at the University of Illinois ay Urbana-Champaign

Apoptosis is an orderly pathway that begins once a cell receives an external death signal and ends with the cell being degraded, phagocytosed, and recycled. Within this pathway are a group of apoptosis regulating proteins called the Bcl-2 family. After receiving its apoptotic signal, Bax, a pro-apoptotic family member, targets the mitochondria. Recent evidence suggests that Bax may interact with cardiolipin, a lipid found only on the outer mitochondrial membrane. We propose that the interaction between Bax and cardiolipin causes a unique conformational change in Bax. This may aid in Bax-mediated mitochondrial permeabilization and the release of apoptogenic agents into the cytosol.

The tryptophan fluorescence emission of Bax was measured between the wavelengths of 320 nm to 400 nm in the presence of small unilamellar vesicles (SUV). The experimental SUV contained 30% cardiolipin with 70% phosphotidylcholine (CL/PC). The positive control for insertion, were SUV that contained 30% phosphotidylglycerol with 70% phophotidylcholine (PG/PC). The negative control SUV contained 100% phosphotidylcholine (DOPC). The tryptophan fluorescence of Bax moved to shorter wavelengths and decreased in emission intensity when added to CL/PC SUV. When Bax was added to PG/PC SUV or to DOPC SUV, the tryptophan fluorescence moved to shorter wavelengths and increased in emission intensity. The increase in emission intensity was lower in DOPC SUV in comparison with PG/PC SUV. The shift of the emission peaks to shorter wavelengths and increase in emission intensities of Bax, in the presence of PG/PC and DOPC SUV, was consistent with Bax moving to a more hydrophobic environment (insertion). The decrease in wavelength when Bax was added to CL/PC SUV was also consistent with Bax inserting into these SUV.  However, the decrease in fluorescence intensity of Bax in these vesicles suggests that the conformation of Bax in the presence of CL/PC is different than the conformation of Bax in the control SUV.

INFLUENCE OF SALT STRESS ON INTERNAL STRUCTURE AND ACROMOLECULE ACCUMULATION IN TWO CULTIVARS OF WEET POTATO [IPOMOEA BATATAS (L.) LAM.] ‘COMMENSAL’ AND SALYBORO’ UNDER IN VITRO CONDITIONS
K. A. Marshall, T.O.Weathington and V. Potluri
Department of Biological Sciences, Chicago State University, Chicago, Illinois 60628

 

Axillary bud cultures of two cultivars of sweet potato [Ipomoea batatas (L.) Lam] “commensal” and “salyboro” were subjected to salt stress under in vitro conditions for 10 weeks.  Relative salt concentrations ranged from 0 to 150 mM.  Upon completion of the allotted growth period, plantet shoot height, number of nodes and dry weight were taken.  In addition, protein, soluble carbohydrate and proline levels were measured as well.  Anatomical observations were conducted on stems using light microscopy.  Analysis revealed that in both cultivars proline accumulation was higher in the shoot.  An increase in soluble carbohydrates and protein was also observed in commensal but only carbohydrate increase was shown in salyboro.  Light microscopy analysis revealed more parenchyma tissue near vascular bundles in commensal while a decrease in tissue and cell size were evident in salyboro in comparison to control.  There was a positive correlation between an increase in carbohydrate content and the size of parenchyma tissue.  These and other results are further discussed in relation to salt tolerance mechanisms of these two cultivars of sweet potato.

DETERMINING THE CORRELATION BETWEEN THE PROLINE ACCUMULATION AND THE ACCUMULATION OF PROTEIN AND SOLUBLE CARBOHYDRATE IN TWO CULTIVARS OF SWEET POTATO UNDER SALT STRESS
G. Nkechiyere Nwani and Dr. D.V. Potluri
Department of Biological Sciences, Chicago State University, Chicago, Illinois 60628

 

Salt stress is a primary factor that affects the crop yield and overall growth of many crops including Sweet Potato (Ipomoea Batatus L). It has been documented that proline is accumulated in Sweet Potato as a method of regulating its osmotic balance however, the exact mechanism as to how proline levels increase are not know (D.P Potluri et al., 1991). To determine the effects of salt stress of sweet potato 242705A & 242707B, plants were subjected to NaCl conc. ranging from 0 to 100mM. It was found that 242705A which was the most tolerant accumulated proline at a more elevated rate than cultivar 242707B. Results also showed that proline synthesis in 242705A cultivar increased as the NaCl was increased. However, little increase was noted in the proline levels of 242707B.

CHARACTERIZATION OF THE FULL-LENGTH ROOTCAR1 PROMOTER IN ALFALFA MESOPHYLL PROTOPLASTS IN   RESPONSE TO EXOGENOUS ABSCISIC ACID
Ikenna Madueke, Denise J. Patrick and Joyce Ache Gana, Department of Biological Sciences, Chicago, Illinois 60628

Ike Madueke

Abiotic stresses such as cold, dehydration, and high salinity, are known to adversely affect plant growth and development. To cope with these stresses, plants have evolved complex biochemical and molecular mechanisms. These stresses increase the phytohormone abscisic acid (ABA) that in turn, regulates large numbers of genes. Alfalfa has one such stress responsive gene, RootCAR1, whose upstream region contains G-box, Myc-like, and Myb-like stress elements. Our objective is to determine if the full length RootCAR1 promoter is inducible by exogenous abscisic acid (ABA) in alfalfa mesophyll protoplasts. A vector containing the RootCAR1 promoter, along with the GUS reporter gene was constructed. Protoplast was isolated from three-week-old alfalfa plants. The pRootCAR1-GUS and the constitutive pCAMV-GUS were introduced to protoplasts by electroporation and polyethylene glycol methods. Protoplasts were treated with 0 (control) to 100 uM ABA and incubated at 25 oC for 24 hours to enable GUS expression. Protoplasts were analyzed for GUS activity by fluorometric analysis.  High GUS activity was obtained in protoplast expressing the constitutive reporter construct, whereas, mixed results were obtained for GUS expression by the ABA treatments.  Our results suggest that the full length RootCAR1 promoter may not be fully activated in alfalfa mesophyll protoplasts. Thus, we are creating several mutants of the RootCAR1 promoter in anticipation of unmasking repressor or activator regions.

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