The ability to non-invasively measure metabolic oxygen flux is a very important tool for physiolo... more The ability to non-invasively measure metabolic oxygen flux is a very important tool for physiologists interested in a variety of questions ranging from basic metabolism, growth/development, and stress adaptation. Technologies for measuring oxygen concentration near the surface of cells/tissues include electrochemical and optical techniques. A wealth of knowledge was gained using these tools for quantifying real-time physiology. Fiber-optic microprobes (optrodes) have recently been developed for measuring oxygen in a variety of biomedical and environmental applications. We have adopted the use of these optical microsensors for plant physiology applications, and used the microsensors in an advanced sensing modality known as self-referencing. Self-referencing is a non-invasive microsensor technique used for measuring realtime flux of analytes. This paper demonstrates the use of optical microsensors for non-invasively measuring rhizosphere oxygen flux associated with respiration in plant roots, as well as boundary layer oxygen flux in phytoplankton mats. Highly sensitive/selective optrodes had little to no hysteresis/calibration drift during experimentation, and an extremely high signal-to-noise ratio. We have used this new tool to compare various aspects of rhizosphere oxygen flux for roots of Glycine max, Zea mays, and Phaseolus vulgaris, and also mapped developmentally relevant profiles and distinct temporal patterns. We also characterized real-time respiratory patterns during inhibition of cytochrome and alternative oxidase pathways via pharmacology. Boundary layer oxygen flux was also measured for a phytoplankton mat during dark:light cycling and exposure to pharamacological inhibitors. This highly sensitive technology enables non-invasive study of oxygen transport in plant systems under physiologically relevant conditions.
ABSTRACT Providing positive and meaningful research experiences to students in their undergraduat... more ABSTRACT Providing positive and meaningful research experiences to students in their undergraduate years is critical for motivating them to pursue advanced degrees or research careers in science and engineering. Such experiences not only offer training for the students in problem solving and critical thinking via hands-on projects, but also offer excellent mentoring and recruiting opportunities for the faculty advisors. The goal of the Research Experience for Undergraduates (REU) Program in the Agricultural and Biological Engineering Department (ABE) at the University of Florida (UF) is to provide eight undergraduate students a unique opportunity to conduct research in water resources using interdisciplinary approaches, integrating research and extension. The students are selected from diverse cultural and educational backgrounds. The eight-week REU Program utilizes the extensive infrastructure of UF - Institute of Food and Agricultural Sciences (IFAS) through the Research and Education Centers (RECs). Two students are paired to participate in their own project under the direct supervision of one of the four research mentors. Four of the eight students are located at the main campus, in Gainesville, Fl, and four remaining students are located off-campus, at the RECs, where some of the ABE faculty are located. The students achieve an enriching cohort experience through social networking, daily blogs, and weekly video conferences to share their research and other REU experiences. The students are co-located during the Orientation week and also during the 5-day Florida Waters Tour. Weekly group meetings and guest lectures are conducted via synchronously through video conferencing. The integration of research and extension is naturally achieved through the projects at the RECs, the guest lectures, Extension workshops, and visits to the Water Management Districts in Florida. In the last two years of the Program, we have received over 80 applicants, from four-year and advanced degree offering institutions and a variety of majors such as Geology, Meteorology, Environmental Sciences & Engineering, Civil Engineering, Water Resources, Agricultural Engineering, Physics, Geography, Chemical Engineering, to name a few. This model of providing integrated research and extension opportunities in hydrology where not all the REU participants are physically co-located, is unique and can be extended to other disciplines.
Although current proposed water recovery systems in space do not incorporate biotreatment technol... more Although current proposed water recovery systems in space do not incorporate biotreatment technologies, research has indicated that bioprocessors (BP) may be a potential primary treatment technology in integrated advanced life support systems for long-duration space missions. Little data have been reported on the activity of nonacidified wastewater in the collection system prior to entering water recovery systems. These reactions are vital in accurately quantifying biosystem performance, mass balances, and microbial kinetics for bioprocessors operated on dynamic wastestreams. The bioavailable dissolved organic carbon and ammonium concentrations of storage tank grab samples may vary by up to 44 ± 9% and 81 ± 12%, respectively, in a urine-containing wastestream. A model for quantifying the average rate of microbially based holding tank activity is presented. A brief enzymatic inhibition study indicated that surfactants contained within the wastestream may be inhibiting feed tank urease activity, causing the organic carbon and ammonium variability. The aim of this research is to quantify storage tank reactions so that future bioprocessor models reflect only the activity occurring within the BP, and not that of the feed tank. Although microbially active collection vessels may be a consideration for long-duration missions, their activity should be modeled independently to avoid the "black box" approach to modeling BP dynamics. The results will aid future researchers in operating biosystems on urine-gray water wastestreams. mon biosystem feed tanks has caused high standard deviations in influent data, significantly affecting bioprocessor removal data . Research on this system employed grab sample techniques at various locations within the system, with the majority of the samples being taken from influent and effluent collection vessels. Some of the problems encountered included inaccurate influent ammonium (NH 4 + ) and dissolved organic carbon (DOC) concentrations. System operation alterations (such as 24-h storage of urine) were made to correct this problem, but the 24h high variability of ammonia (from 120 to 630 mg N/L) and DOC (from 105 to 805 mg DOC/L) in the feed tank persisted. Bioavailable DOC should be estimated for similar wastestreams as the urine within the EPB stream comprises an average of 75% of the DOC, with the remaining 25% being contributed by
The mechanisms by which bone cells sense critically loaded regions of bone are still a matter of ... more The mechanisms by which bone cells sense critically loaded regions of bone are still a matter of ongoing debate. Animal models to investigate response to microdamage involve post mortem immunohistological analysis and do not allow real-time monitoring of cellular response during the emergence of the damage in bone. Most in vitro mechanical stimulation studies are conducted on non-bone substrates, neglecting the damagerelated alterations in the pericellular niche and their potential effects on bone cells. The current study reports spontaneous efflux of calcium ions (Ca 2+ ) (1.924 ± 0.742 pmol cm − 2 s − 1 ) from regions of devitalized bone matrix undergoing post-yield strains, induced by a stress concentrator. When these samples are seeded with MC3T3-E1 osteoblasts, the strain-induced Ca 2+ efflux from bone elicits cell response at the stress concentration site as manifested by activation of intracellular calcium signaling (increase in fluorescence by 52% ± 27%). This activity is associated with extracellular calcium because the intracellular calcium signaling in response to mechanical loading subsides when experiments are repeated using demineralized bone substrates (increase in fluorescence by 6% ± 10%). These results imply a novel perspective where bone matrix acts as an intermediary mechanochemical transducer by converting mechanical strain into a chemical signal (pericellular calcium) to which cells respond. Such a mechanism may be responsible for triggering repair at locations of bone matrix undergoing critical deformation levels.
Indole-3-acetic acid (IAA) is a primary phytohormone that regulates multiple aspects of plant dev... more Indole-3-acetic acid (IAA) is a primary phytohormone that regulates multiple aspects of plant development. Because polar transport of IAA is an essential determinant of organogenesis and dynamic tropic growth, methods to monitor IAA movement in vivo are in demand. A self-referencing electrochemical microsensor was optimized to non-invasively measure endogenous IAA flux near the surface of Zea mays roots without the addition of exogenous IAA. Enhanced sensor surface modification, decoupling of acquired signals, and integrated flux analyses were combined to provide direct, real time quantification of endogenous IAA movement in B73 maize inbred and brachytic2 (br2) auxin transport mutant roots. BR2 is localized in epidermal and hypodermal tissues at the root apex. br2 roots exhibit reduced shootward IAA transport at the root apex in radiotracer experiments and reduced gravitropic growth. IAA flux data indicates that maximal transport occurs in the distal elongation zone of maize roots, and net transport in/out of br2 roots was decreased compared to B73. Integration of short term real time flux data in this zone revealed oscillatory patterns, with B73 exhibiting shorter oscillatory periods and greater amplitude than br2. IAA efflux and influx were inhibited using 1-N-naphthylphthalamic acid (NPA), and 2-naphthoxyacetic acid (NOA), respectively. A simple harmonic oscillation model of these data produced a correlation between modeled and measured values of 0.70 for B73 and 0.69 for br2. These results indicate that this technique is useful for real-time IAA transport monitoring in surface tissues and that this approach can be performed simultaneously with current live imaging techniques.
The ability to non-invasively measure metabolic oxygen flux is a very important tool for physiolo... more The ability to non-invasively measure metabolic oxygen flux is a very important tool for physiologists interested in a variety of questions ranging from basic metabolism, growth/development, and stress adaptation. Technologies for measuring oxygen concentration near the surface of cells/tissues include electrochemical and optical techniques. A wealth of knowledge was gained using these tools for quantifying real-time physiology. Fiber-optic microprobes (optrodes) have recently been developed for measuring oxygen in a variety of biomedical and environmental applications. We have adopted the use of these optical microsensors for plant physiology applications, and used the microsensors in an advanced sensing modality known as self-referencing. Self-referencing is a non-invasive microsensor technique used for measuring realtime flux of analytes. This paper demonstrates the use of optical microsensors for non-invasively measuring rhizosphere oxygen flux associated with respiration in plant roots, as well as boundary layer oxygen flux in phytoplankton mats. Highly sensitive/selective optrodes had little to no hysteresis/calibration drift during experimentation, and an extremely high signal-to-noise ratio. We have used this new tool to compare various aspects of rhizosphere oxygen flux for roots of Glycine max, Zea mays, and Phaseolus vulgaris, and also mapped developmentally relevant profiles and distinct temporal patterns. We also characterized real-time respiratory patterns during inhibition of cytochrome and alternative oxidase pathways via pharmacology. Boundary layer oxygen flux was also measured for a phytoplankton mat during dark:light cycling and exposure to pharamacological inhibitors. This highly sensitive technology enables non-invasive study of oxygen transport in plant systems under physiologically relevant conditions.
ABSTRACT Providing positive and meaningful research experiences to students in their undergraduat... more ABSTRACT Providing positive and meaningful research experiences to students in their undergraduate years is critical for motivating them to pursue advanced degrees or research careers in science and engineering. Such experiences not only offer training for the students in problem solving and critical thinking via hands-on projects, but also offer excellent mentoring and recruiting opportunities for the faculty advisors. The goal of the Research Experience for Undergraduates (REU) Program in the Agricultural and Biological Engineering Department (ABE) at the University of Florida (UF) is to provide eight undergraduate students a unique opportunity to conduct research in water resources using interdisciplinary approaches, integrating research and extension. The students are selected from diverse cultural and educational backgrounds. The eight-week REU Program utilizes the extensive infrastructure of UF - Institute of Food and Agricultural Sciences (IFAS) through the Research and Education Centers (RECs). Two students are paired to participate in their own project under the direct supervision of one of the four research mentors. Four of the eight students are located at the main campus, in Gainesville, Fl, and four remaining students are located off-campus, at the RECs, where some of the ABE faculty are located. The students achieve an enriching cohort experience through social networking, daily blogs, and weekly video conferences to share their research and other REU experiences. The students are co-located during the Orientation week and also during the 5-day Florida Waters Tour. Weekly group meetings and guest lectures are conducted via synchronously through video conferencing. The integration of research and extension is naturally achieved through the projects at the RECs, the guest lectures, Extension workshops, and visits to the Water Management Districts in Florida. In the last two years of the Program, we have received over 80 applicants, from four-year and advanced degree offering institutions and a variety of majors such as Geology, Meteorology, Environmental Sciences & Engineering, Civil Engineering, Water Resources, Agricultural Engineering, Physics, Geography, Chemical Engineering, to name a few. This model of providing integrated research and extension opportunities in hydrology where not all the REU participants are physically co-located, is unique and can be extended to other disciplines.
Although current proposed water recovery systems in space do not incorporate biotreatment technol... more Although current proposed water recovery systems in space do not incorporate biotreatment technologies, research has indicated that bioprocessors (BP) may be a potential primary treatment technology in integrated advanced life support systems for long-duration space missions. Little data have been reported on the activity of nonacidified wastewater in the collection system prior to entering water recovery systems. These reactions are vital in accurately quantifying biosystem performance, mass balances, and microbial kinetics for bioprocessors operated on dynamic wastestreams. The bioavailable dissolved organic carbon and ammonium concentrations of storage tank grab samples may vary by up to 44 ± 9% and 81 ± 12%, respectively, in a urine-containing wastestream. A model for quantifying the average rate of microbially based holding tank activity is presented. A brief enzymatic inhibition study indicated that surfactants contained within the wastestream may be inhibiting feed tank urease activity, causing the organic carbon and ammonium variability. The aim of this research is to quantify storage tank reactions so that future bioprocessor models reflect only the activity occurring within the BP, and not that of the feed tank. Although microbially active collection vessels may be a consideration for long-duration missions, their activity should be modeled independently to avoid the "black box" approach to modeling BP dynamics. The results will aid future researchers in operating biosystems on urine-gray water wastestreams. mon biosystem feed tanks has caused high standard deviations in influent data, significantly affecting bioprocessor removal data . Research on this system employed grab sample techniques at various locations within the system, with the majority of the samples being taken from influent and effluent collection vessels. Some of the problems encountered included inaccurate influent ammonium (NH 4 + ) and dissolved organic carbon (DOC) concentrations. System operation alterations (such as 24-h storage of urine) were made to correct this problem, but the 24h high variability of ammonia (from 120 to 630 mg N/L) and DOC (from 105 to 805 mg DOC/L) in the feed tank persisted. Bioavailable DOC should be estimated for similar wastestreams as the urine within the EPB stream comprises an average of 75% of the DOC, with the remaining 25% being contributed by
The mechanisms by which bone cells sense critically loaded regions of bone are still a matter of ... more The mechanisms by which bone cells sense critically loaded regions of bone are still a matter of ongoing debate. Animal models to investigate response to microdamage involve post mortem immunohistological analysis and do not allow real-time monitoring of cellular response during the emergence of the damage in bone. Most in vitro mechanical stimulation studies are conducted on non-bone substrates, neglecting the damagerelated alterations in the pericellular niche and their potential effects on bone cells. The current study reports spontaneous efflux of calcium ions (Ca 2+ ) (1.924 ± 0.742 pmol cm − 2 s − 1 ) from regions of devitalized bone matrix undergoing post-yield strains, induced by a stress concentrator. When these samples are seeded with MC3T3-E1 osteoblasts, the strain-induced Ca 2+ efflux from bone elicits cell response at the stress concentration site as manifested by activation of intracellular calcium signaling (increase in fluorescence by 52% ± 27%). This activity is associated with extracellular calcium because the intracellular calcium signaling in response to mechanical loading subsides when experiments are repeated using demineralized bone substrates (increase in fluorescence by 6% ± 10%). These results imply a novel perspective where bone matrix acts as an intermediary mechanochemical transducer by converting mechanical strain into a chemical signal (pericellular calcium) to which cells respond. Such a mechanism may be responsible for triggering repair at locations of bone matrix undergoing critical deformation levels.
Indole-3-acetic acid (IAA) is a primary phytohormone that regulates multiple aspects of plant dev... more Indole-3-acetic acid (IAA) is a primary phytohormone that regulates multiple aspects of plant development. Because polar transport of IAA is an essential determinant of organogenesis and dynamic tropic growth, methods to monitor IAA movement in vivo are in demand. A self-referencing electrochemical microsensor was optimized to non-invasively measure endogenous IAA flux near the surface of Zea mays roots without the addition of exogenous IAA. Enhanced sensor surface modification, decoupling of acquired signals, and integrated flux analyses were combined to provide direct, real time quantification of endogenous IAA movement in B73 maize inbred and brachytic2 (br2) auxin transport mutant roots. BR2 is localized in epidermal and hypodermal tissues at the root apex. br2 roots exhibit reduced shootward IAA transport at the root apex in radiotracer experiments and reduced gravitropic growth. IAA flux data indicates that maximal transport occurs in the distal elongation zone of maize roots, and net transport in/out of br2 roots was decreased compared to B73. Integration of short term real time flux data in this zone revealed oscillatory patterns, with B73 exhibiting shorter oscillatory periods and greater amplitude than br2. IAA efflux and influx were inhibited using 1-N-naphthylphthalamic acid (NPA), and 2-naphthoxyacetic acid (NOA), respectively. A simple harmonic oscillation model of these data produced a correlation between modeled and measured values of 0.70 for B73 and 0.69 for br2. These results indicate that this technique is useful for real-time IAA transport monitoring in surface tissues and that this approach can be performed simultaneously with current live imaging techniques.
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Papers by E. McLamore