Bibliographies thématiques / Solvation Dynamics - Biological Water

Littérature scientifique sur le sujet « Solvation Dynamics - Biological Water »

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Publié le 7 septembre 2023

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Articles de revues sur le sujet "Solvation Dynamics - Biological Water"

Cao, Simin, Haoyang Li, Zenan Zhao, Sanjun Zhang, Jinquan Chen, Jianhua Xu, Jay R. Knutson et Ludwig Brand. « Ultrafast Fluorescence Spectroscopy via Upconversion and Its Applications in Biophysics ». Molecules 26, n^o 1 (3 janvier 2021) : 211. http://dx.doi.org/10.3390/molecules26010211.

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In this review, the experimental set-up and functional characteristics of single-wavelength and broad-band femtosecond upconversion spectrophotofluorometers developed in our laboratory are described. We discuss applications of this technique to biophysical problems, such as ultrafast fluorescence quenching and solvation dynamics of tryptophan, peptides, proteins, reduced nicotinamide adenine dinucleotide (NADH), and nucleic acids. In the tryptophan dynamics field, especially for proteins, two types of solvation dynamics on different time scales have been well explored: ~1 ps for bulk water, and tens of picoseconds for “biological water”, a term that combines effects of water and macromolecule dynamics. In addition, some proteins also show quasi-static self-quenching (QSSQ) phenomena. Interestingly, in our more recent work, we also find that similar mixtures of quenching and solvation dynamics occur for the metabolic cofactor NADH. In this review, we add a brief overview of the emerging development of fluorescent RNA aptamers and their potential application to live cell imaging, while noting how ultrafast measurement may speed their optimization.

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Ren, Pengyu, Jaehun Chun, Dennis G. Thomas, Michael J. Schnieders, Marcelo Marucho, Jiajing Zhang et Nathan A. Baker. « Biomolecular electrostatics and solvation : a computational perspective ». Quarterly Reviews of Biophysics 45, n^o 4 (novembre 2012) : 427–91. http://dx.doi.org/10.1017/s003358351200011x.

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AbstractAn understanding of molecular interactions is essential for insight into biological systems at the molecular scale. Among the various components of molecular interactions, electrostatics are of special importance because of their long-range nature and their influence on polar or charged molecules, including water, aqueous ions, proteins, nucleic acids, carbohydrates, and membrane lipids. In particular, robust models of electrostatic interactions are essential for understanding the solvation properties of biomolecules and the effects of solvation upon biomolecular folding, binding, enzyme catalysis, and dynamics. Electrostatics, therefore, are of central importance to understanding biomolecular structure and modeling interactions within and among biological molecules. This review discusses the solvation of biomolecules with a computational biophysics view toward describing the phenomenon. While our main focus lies on the computational aspect of the models, we provide an overview of the basic elements of biomolecular solvation (e.g. solvent structure, polarization, ion binding, and non-polar behavior) in order to provide a background to understand the different types of solvation models.

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Nandi, Nilashis, Kankan Bhattacharyya et Biman Bagchi. « Dielectric Relaxation and Solvation Dynamics of Water in Complex Chemical and Biological Systems ». Chemical Reviews 100, n^o 6 (juin 2000) : 2013–46. http://dx.doi.org/10.1021/cr980127v.

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Trofimov, Yury A., Nikolay A. Krylov et Roman G. Efremov. « Confined Dynamics of Water in Transmembrane Pore of TRPV1 Ion Channel ». International Journal of Molecular Sciences 20, n^o 17 (1 septembre 2019) : 4285. http://dx.doi.org/10.3390/ijms20174285.

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Solvation effects play a key role in chemical and biological processes. The microscopic properties of water near molecular surfaces are radically different from those in the bulk. Furthermore, the behavior of water in confined volumes of a nanometer scale, including transmembrane pores of ion channels, is especially nontrivial. Knowledge at the molecular level of structural and dynamic parameters of water in such systems is necessary to understand the mechanisms of ion channels functioning. In this work, the results of molecular dynamics (MD) simulations of water in the pore and selectivity filter domains of TRPV1 (Transient Receptor Potential Vanilloid type 1) membrane channel are considered. These domains represent nanoscale volumes with strongly amphiphilic walls, where physical behavior of water radically differs from that of free hydration (e.g., at protein interfaces) or in the bulk. Inside the pore and filter domains, water reveals a very heterogeneous spatial distribution and unusual dynamics: It forms compact areas localized near polar groups of particular residues. Residence time of water molecules in such areas is at least 1.5 to 3 times larger than that observed for similar groups at the protein surface. Presumably, these water “blobs” play an important role in the functional activity of TRPV1. In particular, they take part in hydration of the hydrophobic TRPV1 pore by localizing up to six waters near the so-called “lower gate” of the channel and reducing by this way the free energy barrier for ion and water transport. Although the channel is formed by four identical protein subunits, which are symmetrically packed in the initial experimental 3D structure, in the course of MD simulations, hydration of the same amino acid residues of individual subunits may differ significantly. This greatly affects the microscopic picture of the distribution of water in the channel and, potentially, the mechanism of its functioning. Therefore, reconstruction of the full picture of TRPV1 channel solvation requires thorough atomistic simulations and analysis. It is important that the naturally occurring porous volumes, like ion-conducting protein domains, reveal much more sophisticated and fine-tuned regulation of solvation than, e.g., artificially designed carbon nanotubes.

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Sasmal, Dibyendu Kumar, Shirsendu Ghosh, Atanu Kumar Das et Kankan Bhattacharyya. « Solvation Dynamics of Biological Water in a Single Live Cell under a Confocal Microscope ». Langmuir 29, n^o 7 (4 février 2013) : 2289–98. http://dx.doi.org/10.1021/la3043473.

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Karataraki, Georgia, Andreas Sapalidis, Elena Tocci et Anastasios Gotzias. « Molecular Dynamics of Water Embedded Carbon Nanocones : Surface Waves Observation ». Computation 7, n^o 3 (10 septembre 2019) : 50. http://dx.doi.org/10.3390/computation7030050.

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We employed molecular dynamics simulations on the water solvation of conically shaped carbon nanoparticles. We explored the hydrophobic behaviour of the nanoparticles and investigated microscopically the cavitation of water in a conical confinement with different angles. We performed additional molecular dynamics simulations in which the carbon structures do not interact with water as if they were in vacuum. We detected a waving on the surface of the cones that resembles the shape agitations of artificial water channels and biological porins. The surface waves were induced by the pentagonal carbon rings (in an otherwise hexagonal network of carbon rings) concentrated near the apex of the cones. The waves were affected by the curvature gradients on the surface. They were almost undetected for the case of an armchair nanotube. Understanding such nanoscale phenomena is the key to better designed molecular models for membrane systems and nanodevices for energy applications and separation.

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Nandi, Nilashis, Kankan Bhattacharyya et Biman Bagchi. « ChemInform Abstract : Dielectric Relaxation and Solvation Dynamics of Water in Complex Chemical and Biological Systems ». ChemInform 31, n^o 34 (3 juin 2010) : no. http://dx.doi.org/10.1002/chin.200034290.

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Pokharel, Sunil, Shyam Prakash Khanal et N. P. Adhikari. « Solvation free energy of light alkanes in polar and amphiphilic environments ». BIBECHANA 16 (22 novembre 2018) : 92–105. http://dx.doi.org/10.3126/bibechana.v16i0.21136.

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Computer simulations of molecular models are powerful technique that have improved the under- standing of many biochemical phenomena. The method is frequently applied to study the motions of biological macromolecules such as protein and nucleic acids, which can be useful for interpreting the results of certain biophysical experiments. In this work, we have estimated the solvation free energy for light alkane (methane, ethane, propane and n-butane) dissolved in water and methanol respectively over a broad range of temperatures, from 275 K to 375 K, using molecular dynamics simulations. The alkane (methane, ethane, propane and n-butane), and methanol molecules are described by the OPLS-AA (Optimized Potentials for Liquid Simulations-All Atom) potential, while water is modeled by TIP3P (Transferable Intermolecular Potential with 3-Points) model. We have used the free energy perturbation method (Bennett Acceptance Ratio (BAR) method) for the calculation of free energy of solvation. The estimated values of solvation free energy of alkane in the corresponding solvents agree well with the available experimental data.BIBECHANA 16 (2019) 91-104

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Brahma, Rupasree, et H. Raghuraman. « Novel insights in linking solvent relaxation dynamics and protein conformations utilizing red edge excitation shift approach ». Emerging Topics in Life Sciences 5, n^o 1 (8 janvier 2021) : 89–101. http://dx.doi.org/10.1042/etls20200256.

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Protein hydration dynamics plays an important role in many physiological processes since protein fluctuations, slow solvation, and the dynamics of hydrating water are all intrinsically related. Red edge excitation shift (REES) is a unique and powerful wavelength-selective (i.e. excitation-energy dependent) fluorescence approach that can be used to directly monitor the environment-induced restriction and dynamics around a polar fluorophore in a complex biological system. This review is mainly focused on recent applications of REES and a novel analysis of REES data to monitor the structural dynamics, functionally relevant conformational transitions and to unmask the structural ensembles in proteins. In addition, the novel utility of REES in imaging protein aggregates in a cellular context is discussed. We believe that the enormous potential of REES approach showcased in this review will engage more researchers, particularly from life sciences.

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Grotz, Kara K., et Nadine Schwierz. « Magnesium force fields for OPC water with accurate solvation, ion-binding, and water-exchange properties : Successful transfer from SPC/E ». Journal of Chemical Physics 156, n^o 11 (21 mars 2022) : 114501. http://dx.doi.org/10.1063/5.0087292.

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Magnesium plays a vital role in a large variety of biological processes. To model such processes by molecular dynamics simulations, researchers rely on accurate force field parameters for Mg2+ and water. OPC is one of the most promising water models yielding an improved description of biomolecules in water. The aim of this work is to provide force field parameters for Mg2+ that lead to accurate simulation results in combination with OPC water. Using 12 different Mg2+ parameter sets that were previously optimized with different water models, we systematically assess the transferability to OPC based on a large variety of experimental properties. The results show that the Mg2+ parameters for SPC/E are transferable to OPC and closely reproduce the experimental solvation free energy, radius of the first hydration shell, coordination number, activity derivative, and binding affinity toward the phosphate oxygens on RNA. Two optimal parameter sets are presented: MicroMg yields water exchange in OPC on the microsecond timescale in agreement with experiments. NanoMg yields accelerated exchange on the nanosecond timescale and facilitates the direct observation of ion binding events for enhanced sampling purposes.

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Thèses sur le sujet "Solvation Dynamics - Biological Water"

Kropman, Michel François. « Ion solvation in water femtosecond spectroscopy of hydrogen-bond dynamics / ». [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2004. http://dare.uva.nl/document/74586.

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Sedlmeier, Felix [Verfasser], Roland [Akademischer Betreuer] Netz et Martin [Akademischer Betreuer] Zacharias. « Water : Structure, dynamics and solvation / Felix Sedlmeier. Gutachter : Martin Zacharias. Betreuer : Roland Netz ». München : Universitätsbibliothek der TU München, 2011. http://d-nb.info/1019589744/34.

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Spångberg, Daniel. « Cation Solvation in Water and Acetonitrile from Theoretical Calculations ». Doctoral thesis, Uppsala University, Department of Materials Chemistry, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3598.

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Metal ions solvated in aqueous, non-aqueous, and mixtures of solvents occur in many chemical contexts, for example in electrochemical applications and solvent separation. Solvated ions appear in high concentration in the living organisms, where their presence or absence can fundamentally alter the functions of life. In many of these cases, understanding the selective solvation and the dynamics of the ions is essential for the understanding of the processes involved.

Computer simulation provides a molecular level of detail of the solvation process usually not available from experiments. The quality of the interaction models employed in the theoretical description is of particular importance, since even rather small changes in the interaction can lead to substantial and qualitative differences.

This thesis describes the development of a sequence of increasingly refined analytical ion-solvent potentials from ab initio calculations for the systems Li⁺(aq), Na⁺(aq), Mg²⁺(aq), Al³⁺(aq), Li⁺(MeCN), Na⁺(MeCN), Li⁺(aq, MeCN), and Na⁺(aq, MeCN). Molecular dynamics simulations using these potentials were subsequently performed, and some key-properties computed. The reliability of the computed thermodynamical, structural and dynamical properties was scrutinized.

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Yang, Jin. « Ultrafast Protein Hydration Dynamics and Water-Protein Interactions ». The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480668103383892.

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Chung, Ying-Hua. « Water behavior in different biological environments ». Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/1213.

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In this thesis, we report on our studies of water dynamics and structure in various biological environments which include: the surfaces of proteins and various oligosaccharides, the intervening space between proteins; and in the vicinity of cryoprotectant disaccharides in the liquid and ice phases. From a theoretical perspective, we propose methodology to compute diffusivity and residence times on the surface of biomolecules. In particular our proposed algorithm to compute residence times appears to be better in dealing with poor statistics associated with the number of water molecules that remain on a surfaces for extended times. The type of linkage between monomers and the anomeric configuration all play a major role in determining the structure and dynamics of water on the surface of carbohydrates.

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Li, Tanping. « The Coupled Water-Protein Dynamics within Hydration Layer surrounding Protein and Semiclassical Approximation for Optical Response Funtion ». The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1312484867.

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Gaither, Scott P. « Biological Water : A Brief Review of Hydration Dynamics using Complex Systems ». The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1532015941319059.

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Feakes, Karl Anthony. « The distribution and population dynamics of Corixidae ». Thesis, University of Salford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308132.

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Dlamini, Musa V. « Short-Term Water Use Dynamics in Drainage Lysimeters ». DigitalCommons@USU, 2003. https://digitalcommons.usu.edu/etd/5877.

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Turfgrass water use (seasonal turfET) and crop coefficients were determined and a mathematical soil-water balance model for non-weighing drainage lysimeters, which simulates the occurrence (timing and amount) of drainage, was developed. Pairs of non-weighing drainage lysimeters were used to determine crop coefficients for turfgrass in four locations in the state of Utah: Logan Golf and Country Club, Murray Golf Course, Brigham Young University (Spanish Fork) Experiment Farm, and Sunbrook Golf Course (St. George). Daily weather data including air temperature, relative humidity, average wind travel, total solar radiation, precipitation, and average soil temperature were collected with an electronic weather station at each site. Daily precipitation was measured in three sites throughout the season: Murray, Spanish Fork, and Sunbrook. At Logan Golf and Country Club, precipitation was measured to November 10,2002. Water use (averages of two lysimeters) during the growing season varied from 684 to 732 mm for three years (2000- 2002) for the mid-April through late-October observation period at Logan Golf Course; 699 mm for May through October at Murray; 469 mm at Spanish Fork; and 896 mm for late-February through early November at Sunbrook, for 2002 growing season. Calculated seasonal Etr using the 82 Kimberly Penman equation with a 1 00-miles-per-day wind travel limit varied from 1166 to 1229 mm at Logan Golf and Country Club, 1067 mm at Murray, 839 mm at Spanish Fork, and 1574 mm at Sunbrook. Seasonal Etr calculated using the PM ASCE std Etr equation was greater than the 82 Kimberly Peru11an . Seasonal Eto calculated using the FAO#56 Eto equation was less than both the 82 Kimberly Penman and the PM ASCE std Etr equations. Calculated crop coefficients (as a ratio of measured crop water use and calculated potential evapotranspiration) based on alfalfa reference evapotranspiration with the 1982 Kimberly-Penman equation averaged 0.58 for the three years at Logan. Seasonal averages varied from 0.57 to 0.60. Seasonal crop coefficients (2002) were 0.57 for Logan, Spanish Fork, and Sunbrook, and 0.65 for Murray. Short-period crop coefficients also varied within a given season. Short-term crop coefficients derived from a time of wetting and drainage experiment averaged 0.55 at Logan, 0.56 at Murray, 0.60 at Spanish Fork, and 0.56 at Sunbrook.

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McCracken, Justine M. (Justine Meghan) 1979. « Hydrogen bonding and solvation dynamics of n-methylacetamide in denatured water (D₂O) or denatured chloroform (CDCl₃) from nonlinear spectroscopy ». Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28314.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2004.
Vita.
Includes bibliographical references (p. 34-35).
Hydrogen bonding between N-methylacetamide (NMA) and different solvents (D₂O or CDCl₃) was studied by using two-dimensional infrared spectroscopy to probe the frequency fluctuations of the amide I mode of the solvated NMA. An iterative fitting approach was used to extract a correlation function from the experimental data. The correlation function for NMA/D₂O was found to be biexponential with decay constants of 1050 fs and [approximately]50 fs. These timescales are interpreted as reflecting the collective rearrangement of the solution hydrogen bonding network and oscillation of the hydrogen bond bound to the NMA molecule respectively. The correlation function for NMA/CDCl₃ was found to decay on three timescales with two decay constants of 1600 fs and [approximately]50 fs, and a long time quasi-inhomogeneous component.
by Justine M. McCracken.
S.M.

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Livres sur le sujet "Solvation Dynamics - Biological Water"

Erik, Mortensen, dir. Nutrient dynamics and biological structure in shallow freshwater and brackish lakes. Dordrecht : Kluwer Academic Publishers, 1994.

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Bagchi, Biman. Water in Biological and Chemical Processes : From Structure and Dynamics to Function. Cambridge University Press, 2013.

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Costard, René. Ultrafast Dynamics of Phospholipid-Water Interfaces : Studied by Nonlinear Time-Resolved Vibrational Spectroscopy. Springer, 2016.

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Costard, René. Ultrafast Dynamics of Phospholipid-Water Interfaces : Studied by Nonlinear Time-Resolved Vibrational Spectroscopy. Springer, 2015.

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Costard, René. Ultrafast Dynamics of Phospholipid-Water Interfaces : Studied by Nonlinear Time-Resolved Vibrational Spectroscopy. Springer, 2015.

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(Editor), E. Mortensen, E. Jeppesen (Editor), M. Søndergaard (Editor) et L. Kamp Nielsen (Editor), dir. Nutrient Dynamics and Biological Structure in Shallow Freshwater and Brackish Lakes (Developments in Hydrobiology). 2^e éd. Springer, 2007.

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Hussain, Shaukat. Effect of soil water pressures on population dynamics of Fusarium equiseti, Glocladium virens, Talaromyces flavus and Trichoderma viride, biocontrol agents of Verticillium dahliae in potatoes. 1994.

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Nitzan, Abraham. Chemical Dynamics in Condensed Phases. Oxford University Press, 2006. http://dx.doi.org/10.1093/oso/9780198529798.001.0001.

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This text provides a uniform and consistent approach to diversified problems encountered in the study of dynamical processes in condensed phase molecular systems. Given the broad interdisciplinary aspect of this subject, the book focuses on three themes: coverage of needed background material, in-depth introduction of methodologies, and analysis of several key applications. The uniform approach and common language used in all discussions help to develop general understanding and insight on condensed phases chemical dynamics. The applications discussed are among the most fundamental processes that underlie physical, chemical and biological phenomena in complex systems. The first part of the book starts with a general review of basic mathematical and physical methods (Chapter 1) and a few introductory chapters on quantum dynamics (Chapter 2), interaction of radiation and matter (Chapter 3) and basic properties of solids (chapter 4) and liquids (Chapter 5). In the second part the text embarks on a broad coverage of the main methodological approaches. The central role of classical and quantum time correlation functions is emphasized in Chapter 6. The presentation of dynamical phenomena in complex systems as stochastic processes is discussed in Chapters 7 and 8. The basic theory of quantum relaxation phenomena is developed in Chapter 9, and carried on in Chapter 10 which introduces the density operator, its quantum evolution in Liouville space, and the concept of reduced equation of motions. The methodological part concludes with a discussion of linear response theory in Chapter 11, and of the spin-boson model in chapter 12. The third part of the book applies the methodologies introduced earlier to several fundamental processes that underlie much of the dynamical behaviour of condensed phase molecular systems. Vibrational relaxation and vibrational energy transfer (Chapter 13), Barrier crossing and diffusion controlled reactions (Chapter 14), solvation dynamics (Chapter 15), electron transfer in bulk solvents (Chapter 16) and at electrodes/electrolyte and metal/molecule/metal junctions (Chapter 17), and several processes pertaining to molecular spectroscopy in condensed phases (Chapter 18) are the main subjects discussed in this part.

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Pont Evksinskiy – 2021 : materials of XII All-Russian scientific and applied conference for young scientists on the water systems problems, dedicated to the 150 th anniversary of the Sevastopol Biological Station ‒ A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS, Sevastopol, 20–24 September, 2021. IBSS, 2021. http://dx.doi.org/10.21072/978-5-6044865-8-0.

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The book includes materials of young scientists from Russia and the Republic of Abkhazia, revealing various aspects of modern marine and freshwater biology. Abstracts highlight the results of scientific research in the field of population dynamics and genetic differentiation of aquatic organisms, the features of their life cycle. The book present works on the influence of abiotic and anthropogenic environmental factors on the physiological status of aquaculture species. A number of works describes the capabilities of modern research methods applied in marine and freshwater biological studies, such as metabarcoding, "frame" and "rake method" for detecting beach debris, NGS sequencing, and satellite monitoring. In addition, the book reveals the features of the functioning of coastal ecosystems. The book is valuable for young scientists in the field of marine and freshwater biology, water ecology, biotechnology, aquaculture, marine ecology and zoology

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Laurent, Julien, Randal Samstag, Jim Wicks et Ingmar Nopens, dir. CFD Modelling for Wastewater Treatment Processes. IWA Publishing, 2022. http://dx.doi.org/10.2166/9781780409030.

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Abstract This Scientific and Technical Report (STR) provides in-depth fundamentals and guidelines regarding Computational Fluid Dynamics (CFD) simulations of Water Resources Recovery Facilities (WRRFs) unit processes (e.g. headworks, aerobic and anaerobic biological reactors, settling tanks, disinfection). Each unit process is described with respect to: Literature review and process descriptionRelevant CFD concepts and modelling approachCase studiesFuture research needs CFD Modelling for Wastewater Treatment Processes also opens the discussion on two fundamental topics: experimental validation of CFD simulations, and the complementarity between CFD and Chemical Reaction Engineering approaches. This book is intended for undergraduate and graduate students majoring in fields related to wastewater treatment and/or fluid mechanics, as well as researchers and engineers who conduct research and practices in modelling such unit processes. Water resource recovery modelling is not just about lab-scale processes. Now and in the future it is about improving our understanding of (and designing better) full-scale facilities!

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Chapitres de livres sur le sujet "Solvation Dynamics - Biological Water"

Ben-Naim, A. « Solvation Thermodynamics of Biopolymers ». Dans Water and Biological Macromolecules, 430–59. London : Macmillan Education UK, 1993. http://dx.doi.org/10.1007/978-1-349-12359-9_14.

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Kropman, Michel F., Han-Kwang Nienhuys et Huib J. Bakker. « Dynamics of water in ionic solvation shells ». Dans Ultrafast Phenomena XIII, 429–31. Berlin, Heidelberg : Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-642-59319-2_133.

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Markovich, Gil, Stuart Pollack, Rina Giniger et Ori Cheshnovsky. « The Solvation of Halogen Anions in Water Clusters ». Dans Reaction Dynamics in Clusters and Condensed Phases, 13–19. Dordrecht : Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-0786-0_2.

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Fernández, Ariel. « Epistructural Dynamics of Biological Water ». Dans Physics at the Biomolecular Interface, 105–20. Cham : Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-30852-4_4.

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Camisasca, Gaia, Antonio Iorio, Lorenzo Tenuzzo et Paola Gallo. « Slow Dynamics of Biological Water ». Dans Springer Proceedings in Physics, 29–52. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-80924-9_2.

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Resat, Haluk, Fernando O. Raineri, Baw-Ching Perng et Harold L. Friedman. « Temperature Dependence of Ion Solvation Dynamics in Liquid Water ». Dans Hydrogen Bond Networks, 247–50. Dordrecht : Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-015-8332-9_24.

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Beveridge, D. L., S. Swaminathan, G. Ravishanker, J. M. Withka, J. Srinivasan, C. Prevost, S. Louise-May, D. R. Langley, F. M. DiCapua et P. H. Bolton. « Molecular Dynamics Simulations on the Hydration, Structure and Motions of DNA Oligomers ». Dans Water and Biological Macromolecules, 165–225. London : Macmillan Education UK, 1993. http://dx.doi.org/10.1007/978-1-349-12359-9_6.

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Demetropoulos, I. N., I. P. Gerothanassis et D. G. Papageorgiou. « The First Solvation Sphere of N-Methylformamide (NMF) in Water : MM2(87) Force Field and Ab Initio Studies ». Dans Spectroscopy of Biological Molecules, 43–44. Dordrecht : Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0371-8_17.

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Perova, T. S., U. Rasmussen, O. F. Nielsen, S. A. Kirillov, D. H. Christensen et J. K. Vij. « Low-frequency studies and molecular dynamics of water/glycerol mixtures ». Dans Spectroscopy of Biological Molecules : New Directions, 685–86. Dordrecht : Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4479-7_307.

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Kirchner, Barbara, et Dominik Marx. « Hydrophobic Solvation in Liquid Water Via Car-Parrinello Molecular Dynamics : Progress and First Results ». Dans High Performance Computing in Science and Engineering ’01, 228–39. Berlin, Heidelberg : Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/978-3-642-56034-7_22.

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Actes de conférences sur le sujet "Solvation Dynamics - Biological Water"

Martins, Bruna Nery, Allane C. C. Rodrigues, Arsênio P. V. Neto, Ademir J. Camargo et Heibbe C. B. de Oliveira. « Estudo dos efeitos da solvatação aquosa na norepinefrina usando Dinâmica Molecular de Car-Parrinello ». Dans VIII Simpósio de Estrutura Eletrônica e Dinâmica Molecular. Universidade de Brasília, 2020. http://dx.doi.org/10.21826/viiiseedmol2020104.

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Norepinephrine, synthesized from tyrosine, is a neurotransmitter of sympathetic post-ganglion neurons. Norepinephrine regulates many critical functions which include attention, memory, learning and cardiovascular functions. This neurotransmitter has several pharmacological uses, such as adrenergic stimulants, widely used in the treatment of hypertension, cardiac surgery and in myocardial infarction. It is extremely important to study the interaction between drugs and water molecules, for a better understanding of absorption, transport and biological action. Within this context, the Car-Parrinello Molecular Dynamics, by treating the solvent explicitly, becomes ideal for the study of solvated media. In this sense, the objective of this work is to analyze the effects of aqueous solvation on the geometric and electronic parameters of norepinephrine using the Molecular Dynamics of Car-Parrinelo. The solvation dynamics was performed using the CPMD program package (version 4.1). The Radial Distribution Function of the hydrogen and oxygen atoms of the water molecules in the first solvation shell were performed for the O1, O2, O3, N7, H4, H5, H6, H8 and H9 atoms of the norepinephrine. The Radial Distribution Function analyzes indicate that most sites have a well-defined peak (N7, O1, O3, H4, H5 and H6). For the O2, H8 e H9 atoms, there are no well-defined peaks, suggesting that these sites do not interact with the atoms of the water molecules, or even the possibility of intra-molecular interactions. These criteria were considered for the next stages of this work, which are already being carried out, and they are analyzes of possible interactions of hydrogen with these sites.

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Oliveira, Osmair Vital de, Isabella Barros de Oliveira, Felipe Edilino de Lima et Rafael Giordano Viegas. « Encapsulation of the vitamins D3 and E in cucurbit[7]uril : A computational investigation ». Dans VIII Simpósio de Estrutura Eletrônica e Dinâmica Molecular. Universidade de Brasília, 2020. http://dx.doi.org/10.21826/viiiseedmol202066.

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In this work, molecular dynamics simulation (MD) was used to study the encapsulation of fat-soluble vitamins D3 (vD3) and E (a-TOC) into cucubit[7]uril (CB[7]) in an aqueous solution. Cucurbiturils is a class of macrocyclic molecules largely used as carrier and controlled release agent in order to improve the solubility and chemoprotective of drugs. Along 50 ns of MD trajectory, the vitamins formed a stable complex with CB[7] without significantly altering its structure. Moreover, the second solvation shell of the CB[7] was not disrupted by the inclusion of the vitamins. The solvation enthalpy was ~ –173.0 kcal/mol for both complexes and –177.6 kcal/mol for the isolated CB[7], suggesting that the vitamin@CB[7] complexes are soluble in water. The binding free energy indicates that CB[7] can act as carrier agent for these vitamins, with values of –17.54 and –23.76 kcal/mol for vD3@CB[7] and a-TOC@CB[7], respectively. Finally, herein we highlight that CB[7] can be a new host to be used for vitamin delivery in biological systems.

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Kropman, Michel F., Han-Kwang Nienhuys et Huib J. Bakker. « Dynamics of water in ionic solvation shells ». Dans International Conference on Ultrafast Phenomena. Washington, D.C. : OSA, 2002. http://dx.doi.org/10.1364/up.2002.md7.

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Fainberg, B. D., B. Zolotov, A. Gan, S. Y. Goldberg et D. Huppert. « ‘‘Population’’ transient four-photon spectroscopy of solvation dynamics ». Dans The 54th international meeting of physical chemistry : Fast elementary processes in chemical and biological systems. AIP, 1996. http://dx.doi.org/10.1063/1.50158.

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Long, Frederick H., Hong Lu et Kenneth B. Eisenthal. « Femtosecond Studies of Electrons in Water ». Dans International Conference on Ultrafast Phenomena. Washington, D.C. : Optica Publishing Group, 1990. http://dx.doi.org/10.1364/up.1990.wb3.

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Although the equilibrium properties of the aqueous electron have been well-studied, the solvation dynamics and other non-equilibrium properties are still not well understood. A fundamental question concerning the electron solvation dynamics is the nature of the transition from the wet electron to the solvated or equilibrium electron. Theoretical studies have predicted dynamics involving a continous change in the electron absorption spectra.1 Early experimental work has claimed that only two-states were involved, i.e. the solvation dynamics were not continous.2 In order to resolve these issues we have done experiments with improved time resolution and have looked for an isosbestic point in the solvation dynamics.3

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Eilers-König, N., T. Kühne, J. Schroeder, D. Schwarzer, J. Troe et P. Vöhringer. « Solvation dynamics of 4-(N,N-dimethylamino)-4ʹ-cyanostilbene in polar solvents ». Dans The 54th international meeting of physical chemistry : Fast elementary processes in chemical and biological systems. AIP, 1996. http://dx.doi.org/10.1063/1.50162.

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Kundu, Achintya, Shavkat I. Mamatkulov, Florian N. Brünig, Douwe Jan Bonthuis, Roland R. Netz, Thomas Elsaesser et Benjamin P. Fingerhut. « Short-Range Slowdown of Water Solvation Dynamics around SO42- - Mg2+ Ion Pairs ». Dans International Conference on Ultrafast Phenomena. Washington, D.C. : Optica Publishing Group, 2022. http://dx.doi.org/10.1364/up.2022.f2a.2.

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2D-IR spectroscopy in the fingerprint region of SO42- ions in water reveals a counterion specific slowdown of solvation dynamics. Hydration structures of solvent shared SO42- - Mg2+ ion pairs are identified as the molecular origin.

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Patawane, Sanwardhini, Shashank Pant et Niharendu Choudhury. « Solvation of fullerene in a course grained water : A molecular dynamics simulation study ». Dans NANOFORUM 2014. AIP Publishing LLC, 2015. http://dx.doi.org/10.1063/1.4917637.

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Mialocq, J. C., T. Gustavsson, S. Pommeret, G. Baldacchino, P. Hébert et R. Naskrecki. « Ultrafast solvation dynamics of styrenic probes. Different behavior of polar and non-polar excited singlet states ». Dans The 54th international meeting of physical chemistry : Fast elementary processes in chemical and biological systems. AIP, 1996. http://dx.doi.org/10.1063/1.50161.

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Gauduel, Y., J. L. Martin, A. Migus, N. Yamada et A. Antonetti. « Femtosecond Study of Electron Localization and Solvation in Pure Water ». Dans International Conference on Ultrafast Phenomena. Washington, D.C. : Optica Publishing Group, 1986. http://dx.doi.org/10.1364/up.1986.tha6.

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The mechanisms governing the localization and solvation of excess electrons in liquids and glasses are one of the fundamental and still unsolved problems in the physics and chemistry of condensed phase. Laser photolysis of solute molecules and pulse radiolysis of polar fluids have been extensively used to generate excess electron and to investigate the initial steps leading to the long lifetime state of solvated electron. However, very little is known about the dynamics of electron solvation in liquid water. The best available measurement gives an upper limite of 0.3 ps for the appearance of solvated electron after a UV photolysis of an aqueous solution of ferrocyanure[1]. It has not been possible up to now to clearly demonstrate whether the infrared absorbing state, identified in alcools as a localized and a precursor of the fully relaxed solvated state[2], has its analog in pure liquid water.

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Rapports d'organisations sur le sujet "Solvation Dynamics - Biological Water"

Desiderati, Christopher. Carli Creek Regional Water Quality Project : Assessing Water Quality Improvement at an Urban Stormwater Constructed Wetland. Portland State University, 2022. http://dx.doi.org/10.15760/mem.78.

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Stormwater management is an ongoing challenge in the United States and the world at-large. As state and municipal agencies grapple with conflicting interests like encouraging land development, complying with permits to control stormwater discharges, “urban stream syndrome” effects, and charges to steward natural resources for the long-term, some agencies may turn to constructed wetlands (CWs) as aesthetically pleasing and functional natural analogs for attenuating pollution delivered by stormwater runoff to rivers and streams. Constructed wetlands retain pollutants via common physical, physicochemical, and biological principles such as settling, adsorption, or plant and algae uptake. The efficacy of constructed wetlands for pollutant attenuation varies depending on many factors such as flow rate, pollutant loading, maintenance practices, and design features. In 2018, the culmination of efforts by Clackamas Water Environment Services and others led to the opening of the Carli Creek Water Quality Project, a 15-acre constructed wetland adjacent to Carli Creek, a small, 3500-ft tributary of the Clackamas River in Clackamas County, OR. The combined creek and constructed wetland drain an industrialized, 438-acre, impervious catchment. The wetland consists of a linear series of a detention pond and three bioretention treatment cells, contributing a combined 1.8 acres of treatment area (a 1:243 ratio with the catchment) and 3.3 acre-feet of total runoff storage. In this study, raw pollutant concentrations in runoff were evaluated against International Stormwater BMP database benchmarks and Oregon Water Quality Criteria. Concentration and mass-based reductions were calculated for 10 specific pollutants and compared to daily precipitation totals from a nearby precipitation station. Mass-based reductions were generally higher for all pollutants, largely due to runoff volume reduction on the treatment terrace. Concentration-based reductions were highly variable, and suggested export of certain pollutants (e.g., ammonia), even when reporting on a mass-basis. Mass load reductions on the terrace for total dissolved solids, nitrate+nitrite, dissolved lead, and dissolved copper were 43.3 ± 10%, 41.9 ± 10%, 36.6 ± 13%, and 43.2 ± 16%, respectively. E. coli saw log-reductions ranging from -1.3 — 3.0 on the terrace, and -1.0 — 1.8 in the creek. Oregon Water Quality Criteria were consistently met at the two in-stream sites on Carli Creek for E. coli with one exception, and for dissolved cadmium, lead, zinc, and copper (with one exception for copper). However, dissolved total solids at the downstream Carli Creek site was above the Willamette River guidance value 100 mg/L roughly 71% of the time. The precipitation record during the study was useful for explaining certain pollutant reductions, as several mechanisms are driven by physical processes, however it was not definitive. The historic rain/snow/ice event in mid-February 2021 appeared to impact mass-based reductions for all metals. Qualitatively, precipitation seemed to have the largest effect on nutrient dynamics, specifically ammonia-nitrogen. Determining exact mechanisms of pollutant removals was outside the scope of this study. An improved flow record, more targeted storm sampling, or more comprehensive nutrient profiles could aid in answering important questions on dominant mechanisms of this new constructed wetland. This study is useful in establishing a framework and baseline for understanding this one-of-a-kind regional stormwater treatment project and pursuing further questions in the future.

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Altman, Safra, R. Harris, S. McKay, Michael Kjelland et Todd Swannack. Oyster reef connectivity : ecological benefits and associated vulnerabilities. Engineer Research and Development Center (U.S.), août 2022. http://dx.doi.org/10.21079/11681/45020.

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Global oyster abundance has declined ~85 % over the past 200 years, primarily because of overharvesting (Beck, Brumbaugh, and Airoldi 2011; Kirby 2004). Healthy oyster reef systems benefit the environment in many ways, including water-quality improvement, shoreline protection, increased biological and habitat diversity, and carbon sequestration. To maintain these environmental benefits, reef-restoration efforts that produce healthy, sustainable oyster reefs are essential. To this end, the US Army Corps of Engineers (USACE) has been involved in reef-restoration projects in many locations, including extensive efforts in the Chesapeake Bay (Virginia, Maryland), coastal regions of New York and New Jersey, and the Gulf of Mexico. There are many benefits to creating and maintaining oyster reef systems that are well connected, for both oysters and other organisms within the reef and surrounding habitats. This technical note presents the current knowledge of benefits and costs to restore oyster-reef connectivity along the East and Gulf Coasts of North America. Connectivity of oyster reefs can refer to the physical location of reefs with respect to one another as well as to the dynamics of the genetic links within a metapopulation or to the extent to which larval transport and recruitment unite reef communities. For the purposes of this technical note, connectivity is defined as the spatial aggregation of reefs, though we address impacts of genetic and larval flow as well. Reef connectivity positively affects many ecosystem services and dynamics but can also have unintended consequences (that is, negative externalities). This technical note reviews the benefits and costs of increasing connectivity and presents a brief example of how trade-offs may occur between these potentially opposing ecological objectives. Here, we focus on the eastern oyster, Crassostrea virginica, which inhabits the East and Gulf Coasts of North America, though many of the concepts and principles discussed may apply to other oyster species as well.

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Spiegel, Yitzhak, Michael McClure, Itzhak Kahane et B. M. Zuckerman. Characterization of the Phytophagous Nematode Surface Coat to Provide New Strategies for Biocontrol. United States Department of Agriculture, novembre 1995. http://dx.doi.org/10.32747/1995.7613015.bard.

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Chemical composition and biological role of the surface coat (SC) of the root-knot nematodes, Meloidogyne spp. are described. SC proteins of M. incognita race 3 infective juveniles (J2) were characterized by electrophoresis and western blotting of extracts from radioiodine and biotin-labelled nematodes. J2 labelled with radioiodine and biotin released 125I and biotin-labelled molecules into water after 20 hours incubation, indicating that SC proteins may be loosely attached to the nematode. Antiserum to the principal protein reacted with the surface of live J2 and with surface proteins previously separated by electrophoresis. Human red blood cells (HRBC) adhered to J2 of several tylenchid nematodes over the entire nematode body. HRBC adhered also to nylon fibers coated with SC extracted from M. javanica J2; binding was Ca++/Mg++ dependent, and decreased when the nylon fibers were coated with bovine serum albumin, or pre-incubated with fucose and mannose. These experiments support a working hypothesis that RBC adhesion involves carbohydrate moieties of HRBC and carbohydrate-recognition domain(s) (CRD) distributed on the nematode surface. To our knowledge, this is the first report of a surface CRD i the phylum Nematoda. Gold-conjugated lectins and neoglycoproteins combined with silver enhancement have been used for the detection of carbohydrates and CRD, respectively, on the SC of M. javanica J2. Biotin reagents were used to trace surface proteins, specifically, on live J2. The labile and transitory nature of the SC was demonstrated by the dynamics of HRBC adherence to detergent-treated J2, J2 at different ages or fresh-hatched J2 held at various temperatures. SC recovery was demonstrated also by a SDS-PAGE profile. Monoclonal antibodies developed to a cuticular protein of M. incognita J2 gave a slight, but significant reduction in attachment of Pasteuria penetrans spores. Spore attachment as affected by several enzymes was inconsistent: alcian blue, which specifically blocks sulfyl groups, had no afffect on spore attachment. Treatment with cationized ferritin alone or catonized ferritin following monoclonal antibody caused significant decreases in spore attachment. Those results suggest a role in attachment by negatively charged groups.

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Belkin, Shimshon, Sylvia Daunert et Mona Wells. Whole-Cell Biosensor Panel for Agricultural Endocrine Disruptors. United States Department of Agriculture, décembre 2010. http://dx.doi.org/10.32747/2010.7696542.bard.

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Objectives: The overall objective as defined in the approved proposal was the development of a whole-cell sensor panel for the detection of endocrine disruption activities of agriculturally relevant chemicals. To achieve this goal several specific objectives were outlined: (a) The development of new genetically engineered wholecell sensor strains; (b) the combination of multiple strains into a single sensor panel to effect multiple response modes; (c) development of a computerized algorithm to analyze the panel responses; (d) laboratory testing and calibration; (e) field testing. In the course of the project, mostly due to the change in the US partner, three modifications were introduced to the original objectives: (a) the scope of the project was expanded to include pharmaceuticals (with a focus on antibiotics) in addition to endocrine disrupting chemicals, (b) the computerized algorithm was not fully developed and (c) the field test was not carried out. Background: Chemical agents, such as pesticides applied at inappropriate levels, may compromise water quality or contaminate soils and hence threaten human populations. In recent years, two classes of compounds have been increasingly implicated as emerging risks in agriculturally-related pollution: endocrine disrupting compounds (EDCs) and pharmaceuticals. The latter group may reach the environment by the use of wastewater effluents, whereas many pesticides have been implicated as EDCs. Both groups pose a threat in proportion to their bioavailability, since that which is biounavailable or can be rendered so is a priori not a threat; bioavailability, in turn, is mediated by complex matrices such as soils. Genetically engineered biosensor bacteria hold great promise for sensing bioavailability because the sensor is a live soil- and water-compatible organism with biological response dynamics, and because its response can be genetically “tailored” to report on general toxicity, on bioavailability, and on the presence of specific classes of toxicants. In the present project we have developed a bacterial-based sensor panel incorporating multiple strains of genetically engineered biosensors for the purpose of detecting different types of biological effects. The overall objective as defined in the approved proposal was the development of a whole-cell sensor panel for the detection of endocrine disruption activities of agriculturally relevant chemicals. To achieve this goal several specific objectives were outlined: (a) The development of new genetically engineered wholecell sensor strains; (b) the combination of multiple strains into a single sensor panel to effect multiple response modes; (c) development of a computerized algorithm to analyze the panel responses; (d) laboratory testing and calibration; (e) field testing. In the course of the project, mostly due to the change in the US partner, three modifications were introduced to the original objectives: (a) the scope of the project was expanded to include pharmaceuticals (with a focus on antibiotics) in addition to endocrine disrupting chemicals, (b) the computerized algorithm was not fully developed and (c) the field test was not carried out. Major achievements: (a) construction of innovative bacterial sensor strains for accurate and sensitive detection of agriculturally-relevant pollutants, with a focus on endocrine disrupting compounds (UK and HUJ) and antibiotics (HUJ); (b) optimization of methods for long-term preservation of the reporter bacteria, either by direct deposition on solid surfaces (HUJ) or by the construction of spore-forming Bacillus-based sensors (UK); (c) partial development of a computerized algorithm for the analysis of sensor panel responses. Implications: The sensor panel developed in the course of the project was shown to be applicable for the detection of a broad range of antibiotics and EDCs. Following a suitable development phase, the panel will be ready for testing in an agricultural environment, as an innovative tool for assessing the environmental impacts of EDCs and pharmaceuticals. Furthermore, while the current study relates directly to issues of water quality and soil health, its implications are much broader, with potential uses is risk-based assessment related to the clinical, pharmaceutical, and chemical industries as well as to homeland security.

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Or, Dani, Shmulik Friedman et Jeanette Norton. Physical processes affecting microbial habitats and activity in unsaturated agricultural soils. United States Department of Agriculture, octobre 2002. http://dx.doi.org/10.32747/2002.7587239.bard.

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experimental methods for quantifying effects of water content and other dynamic environmental factors on bacterial growth in partially-saturated soils. Towards this end we reviewed critically the relevant scientific literature and performed theoretical and experimental studies of bacterial growth and activity in modeled, idealized and real unsaturated soils. The natural wetting-drying cycles common to agricultural soils affect water content and liquid organization resulting in fragmentation of aquatic habitats and limit hydraulic connections. Consequently, substrate diffusion pathways to soil microbial communities become limiting and reduce nutrient fluxes, microbial growth, and mobility. Key elements that govern the extent and manifestation of such ubiquitous interactions include characteristics of diffusion pathways and pore space, the timing, duration, and extent of environmental perturbations, the nature of microbiological adjustments (short-term and longterm), and spatial distribution and properties of EPS clusters (microcolonies). Of these key elements we have chosen to focus on a manageable subset namely on modeling microbial growth and coexistence on simple rough surfaces, and experiments on bacterial growth in variably saturated sand samples and columns. Our extensive review paper providing a definitive “snap-shot” of present scientific understanding of microbial behavior in unsaturated soils revealed a lack of modeling tools that are essential for enhanced predictability of microbial processes in soils. We therefore embarked on two pronged approach of development of simple microbial growth models based on diffusion-reaction principles to incorporate key controls for microbial activity in soils such as diffusion coefficients and temporal variations in soil water content (and related substrate diffusion rates), and development of new methodologies in support of experiments on microbial growth in simple and observable porous media under controlled water status conditions. Experimental efforts led to a series of microbial growth experiments in granular media under variable saturation and ambient conditions, and introduction of atomic force microscopy (AFM) and confocal scanning laser microscopy (CSLM) to study cell size, morphology and multi-cell arrangement at a high resolution from growth experiments in various porous media. The modeling efforts elucidated important links between unsaturated conditions and microbial coexistence which is believed to support the unparallel diversity found in soils. We examined the role of spatial and temporal variation in hydration conditions (such as exist in agricultural soils) on local growth rates and on interactions between two competing microbial species. Interestingly, the complexity of soil spaces and aquatic niches are necessary for supporting a rich microbial diversity and the wide array of microbial functions in unsaturated soils. This project supported collaboration between soil physicists and soil microbiologist that is absolutely essential for making progress in both disciplines. It provided a few basic tools (models, parameterization) for guiding future experiments and for gathering key information necessary for prediction of biological processes in agricultural soils. The project sparked a series of ongoing studies (at DTU and EPFL and in the ARO) into effects of soil hydration dynamics on microbial survival strategy under short term and prolonged desiccation (important for general scientific and agricultural applications).

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Needham, Glenn R., Uri Gerson, Gloria DeGrandi-Hoffman, D. Samatero, J. Yoder et William Bruce. Integrated Management of Tracheal Mite, Acarapis woodi, and of Varroa Mite, Varroa jacobsoni, Major Pests of Honey Bees. United States Department of Agriculture, mars 2000. http://dx.doi.org/10.32747/2000.7573068.bard.

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Objectives: The Israeli work plan regarding HBTM included: (a) producing a better diagnostic method; (b) following infestations during the season and evaluating damage to resistant bees and, (c) controlling HBTM by conventional means under local conditions. For varroa our plans to try novel control (e.g. oil novel control (e.g. oil patties & essential oils) were initially delayed by very low pest populations, then disrupted by the emergence of fluvalinate resistance. We monitored the spread of resistance to understand it better, and analyzed an underlying biochemical resistance mechanism in varroa. The US work plan focused on novel management methods for both mites with an emphasis on reducing use of traditional insecticides due to resistance and contamination issues. Objectives were: (a) evaluating plant essential oils for varroa control; (b) exploring the vulnerability of varroa to desiccation for their management; and (c) looking for biological variation in HBTM that could explain virulence variability between colonies. Although the initial PI at the USDA Beltsville Bee Lab, W.A. Bruce, retired during the project we made significant strides especially on varroa water balance. Subcontracts were performed by Yoder (Illinois College) on varroa water balance and DeGrandi-Hoffman (USDA) who evaluated plant essential oils for their potential to control varroa. We devised an IPM strategy for mite control i the U.S. Background: Mites that parasitize honey bees are a global problem. They are threatening the survival of managed and feral bees, the well-being of commercial/hobby beekeeping, and due to pollination, the future of some agricultural commodities is threatened. Specific economic consequences of these mites are that: (a) apiculture/breeder business are failing; (b) fewer colonies exist; (c) demand and cost for hive leasing are growing; (d) incidences of bee pathogens are increasing; and, (e) there are ore problems with commercial-reared bees. As a reflection of the continued significance f bee mites, a mite book is now in press (Webster & delaplane, 2000); and the 2nd International Conference on Africanized Honey Bees and Bee Mites is scheduled (April, 2000, Arizona). The first such conference was at OSU (1987, GRN was co-organizer). The major challenge is controlling two very different mites within a colony while not adversely impacting the hive. Colony management practices vary, as do the laws dictating acaricide use. Our basic postulates were that: (a) both mites are of economic importance with moderate to high infestations but not at low rates and, (b) once established they will not be eradicated. A novel strategy was devised that deals with the pests concomitantly by maintaining populations at low levels, without unnecessary recourse to synthetic acaricides. Major Conclusions, Solutions, Achievements: A major recent revelation is that there are several species of "Varroa jacobsoni" (Anderson & Trueman 1999). Work on control, resistance, population dynamics, and virulence awaits knowing whether this is a problem. In the U.S. there was no difference between varroa from three locales in terms of water balance parameters (AZ, MN & PA), which bodes well for our work to date. Winter varroa (U.S.) were more prone to desiccation than during other seasons. Varroa sensitivity to desiccation has important implications for improving IPM. Several botanicals showed some promise for varroa control (thymol & origanum). Unfortunately there is varroa resistance to Apistan in Israel but a resistance mechanism was detected for the first time. The Israel team also has a new method for HBTM diagnosis. Annual tracheal mite population trends in Israel were characterized, which will help in targeting treatment. Effects of HBTM on honey yields were shown. HBTM control by Amitraz was demonstrated for at least 6 months. Showing partial resistance by Buckfast bees to HBTM will be an important IPM tactic in Israel and U.S.

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