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- Anhydrobiosis (Life without Water) (7)
- Cell Stabilization (Preconditioning) (6)
- Diapause (5)
- Allosteric Regulation (Respiratory Pigments) (4)
- Anhydrobiosis (4)
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- Anoxia (4)
- Metabolic depression (4)
- Mitochondrial Physiology (4)
- Trehalose (4)
- Apoptosis (Programmed Cell Death) (3)
- Artemia franciscana (3)
- Homarus vulgaris (3)
- Intrinsically disordered proteins (3)
- Lobster (3)
- Caffeine (2)
- Cell Stabilization (Lyopreservation) (2)
- Desiccation tolerance (2)
- Hemocyanin (2)
- Isothermal titration calorimetry (2)
- Metabolic preconditioning (2)
- Mitochondria (2)
- Teleostei (2)
- Temperature (2)
- Urate (2)
- ATP (1)
- Accelerated senescence (1)
- Adherent cell monolayer (1)
- Aging (1)
- Allosteric model (1)
- Apaf-1 (1)
Articles 1 - 27 of 27
Full-Text Articles in Life Sciences
Tradeoffs Of Warm Adaptation In Aquatic Ectotherms: Live Fast, Die Young?, A. P. Porreca, E. Martinez, R. E. Colombo, Michael A. Menze
Tradeoffs Of Warm Adaptation In Aquatic Ectotherms: Live Fast, Die Young?, A. P. Porreca, E. Martinez, R. E. Colombo, Michael A. Menze
Michael Menze
In the face of a changing climate, questions regarding sub-lethal effects of elevated habitat temperature on the physiology of ectotherms remain unanswered. In particular, long-term responses of ectotherms to the warming trend in tropical regions are unknown and significantly understudied due primarily to the difficulties in specimen and community traceability. In freshwater lakes employed as cooling reservoirs for power plants, increased physiological stress from high water temperature can lead to an increase in mortality, reduce growth, and potentially alter the community structure of fishes. Throughout this study, we employ this highly tractable system to assess how elevated thermal regimes can …
Physiological Performance Of Warm-Adapted Marine Ectotherms: Thermal Limits Of Mitochondrial Energy Transduction Efficiency, Eloy Martinez, Eric Hendricks, Michael A. Menze, Joseph J. Torres
Physiological Performance Of Warm-Adapted Marine Ectotherms: Thermal Limits Of Mitochondrial Energy Transduction Efficiency, Eloy Martinez, Eric Hendricks, Michael A. Menze, Joseph J. Torres
Michael Menze
Thermal regimes in aquatic systems have profound implications for the physiology of ectotherms. In particular, the effect of elevated temperatures on mitochondrial energy transduction (i.e. energy from carbon substrates to ATP) in tropical and subtropical teleosts may have profound consequences on organismal performance and population viability. Upper and lower whole-organism critical temperatures for teleosts suggest that subtropical and tropical species are not susceptible to the warming trends associated with climate change, but sub-lethal effects on energy transduction efficiency and population dynamics remain unclear. The goal of the present study was to compare the thermal sensitivity of processes associated with mitochondrial …
Molecular Approaches For Improving Desiccation Tolerance: Insights From The Brine Shrimp Artemia Franciscana, Steven C. Hand, Michael A. Menze
Molecular Approaches For Improving Desiccation Tolerance: Insights From The Brine Shrimp Artemia Franciscana, Steven C. Hand, Michael A. Menze
Michael Menze
Main conclusion We have evaluated the endogenous expression and molecular properties of selected Group 3 LEA proteins from Artemia franciscana , and the capacity of selected Groups 1 and 3 proteins transfected into various desiccation-sensitive cell lines to improve tolerance to drying. Organisms inhabiting both aquatic and terrestrial ecosystems frequently are confronted with the problem of water loss for multiple reasons—exposure to hypersalinity, evaporative water loss, and restriction of intracellular water due to freezing of extracellular fluids. Seasonal desiccation can become severe and lead to the production of tolerant propagules and entry into the state of anhydrobiosis at various stages …
Cryopreservation Of Hepatocyte (Hepg2) Cell Monolayers: Impact Of Trehalose, Blake Stokich, Quinn Osgood, David Grimm, Shhyam Moorthy, Nilay Chakraborty, Michael A. Menze
Cryopreservation Of Hepatocyte (Hepg2) Cell Monolayers: Impact Of Trehalose, Blake Stokich, Quinn Osgood, David Grimm, Shhyam Moorthy, Nilay Chakraborty, Michael A. Menze
Michael Menze
A simple method to cryogenically preserve hepatocyte monolayers is currently not available but such a technique would facilitate numerous applications in the field of biomedical engineering, cell line development, and drug screening. We investigated the effect of trehalose and dimethyl sulfoxide (Me2SO) in cryopreservation of human hepatocellular carcinoma (HepG2) cells in suspension and monolayer formats. HepG2 cell monolayers were incubated for 24 h at varying concentrations of trehalose (50–150 mM) prior to cryopreservation to identify the optimum concentration for such preincubation. When trehalose alone was used as the cryoprotective agent (CPA), cells in monolayer format did not survive freezing while …
Genetic Engineering, A Hope For Sustainable Biofuel Production: Review, Sudip Paudel, Michael A. Menze
Genetic Engineering, A Hope For Sustainable Biofuel Production: Review, Sudip Paudel, Michael A. Menze
Michael Menze
The use of recently developed genetic engineering tools in combination with organisms that have the potential to produce precursors for the production of biodiesel, promises a sustainable and environment friendly energy source. Enhanced lipid production in wild type and/or genetically engineered organisms can offer sufficient raw material for industrial transesterification of plant-based triglycerides. Bio-diesel, produced with the help of genetically modified organisms, might be one of the best alternatives to fossil fuels and to mitigate various environmental hazards.
Identification Of Disufide Bond Formation Between Mitoneet And Glutamate Dehydrogenase 1, Morgan E. Roberts, Jacquelyn P. Crail, Megan M. Laffoon, William G. Fernandez, Michael A. Menze, Mary E. Konkle
Identification Of Disufide Bond Formation Between Mitoneet And Glutamate Dehydrogenase 1, Morgan E. Roberts, Jacquelyn P. Crail, Megan M. Laffoon, William G. Fernandez, Michael A. Menze, Mary E. Konkle
Michael Menze
MitoNEET is a protein that was identified as a drug target for diabetes, but its cellular function as well as its role in diabetes remains elusive. Protein pull-down experiments identified glutamate dehydrogenase 1 (GDH1) as a potential binding partner. GDH1 is a key metabolic enzyme with emerging roles in insulin regulation. MitoNEET forms a covalent complex with GDH1 through disulfide bond formation and acts as an activator. Proteomic analysis identified the specific cysteine residues that participate in the disulfide bond. This is the first report that effectively links mitoNEET to activation of the insulin regulator GDH1.
Improved Tolerance To Salt And Water Stress In Drosophila Melanogaster Cells Conferred By Late Embryogenesis Abundant Protein, Matthew R. Marunde, Dilini A. Samarajeewa, John Anderson, Shumin Li, Steven C. Hand, Michael A. Menze
Improved Tolerance To Salt And Water Stress In Drosophila Melanogaster Cells Conferred By Late Embryogenesis Abundant Protein, Matthew R. Marunde, Dilini A. Samarajeewa, John Anderson, Shumin Li, Steven C. Hand, Michael A. Menze
Michael Menze
Mechanisms that govern anhydrobiosis involve the accumulation of highly hydrophilic macromolecules, such as late embryogenesis abundant (LEA) proteins. Group 1 LEA proteins comprised of 181 (AfLEA1.1) and 197 (AfLEA1.3) amino acids were cloned from embryos of Artemia franciscana and expressed in Drosophila melanogaster cells (Kc167). Confocal microscopy revealed a construct composed of green fluorescence protein (GFP) and AfLEA1.3 accumulates in the mitochondria (AfLEA1.3-GFP), while AfLEA1.1-GFP was found in the cytoplasm. In the presence of mixed substrates, oxygen consumption was statistically identical for permeabilized Kc167 control and Kc167-AfLEA1.3 cells. Acute titrations of permeabilized cells with NaCl up to 500 mM led …
Diapause And Anhydrobiosis In Embryos Of Artemia Franciscana: Metabolic Depression, Lea Proteins And Water Stress, Steven C. Handel, Yuvraj Patil, Shumin Li, Nilay Charkraborty, Arpurva Borcar, Michael A. Menze, Leaf C. Boswell, Daniel Moore, Mehmet Toner
Diapause And Anhydrobiosis In Embryos Of Artemia Franciscana: Metabolic Depression, Lea Proteins And Water Stress, Steven C. Handel, Yuvraj Patil, Shumin Li, Nilay Charkraborty, Arpurva Borcar, Michael A. Menze, Leaf C. Boswell, Daniel Moore, Mehmet Toner
Michael Menze
Metabolic depression is typically correlated with extended survival of environmental challenge and energy-limitation in early life stages of various invertebrates and vertebrates. Diapause is an ontogenetically-programmed reduction of development and often metabolism seen in many invertebrates. When embryos of Artemia franciscana enter the state of diapause, the overall metabolic depression is estimated to be greater than 99%. These embryos also contain trehalose and express multiple isoforms of Late Embryogenesis Abundant (LEA) proteins, constituents often present in a number of such anhydrobiotic animals. The mRNA levels for LEA proteins are highest in diapause and post-diapause embryos that possess desiccation tolerance, but …
Late Embryogenesis Abundant Proteins Protect Human Hepatoma Cells During Acute Desiccation, Shumin Li, Nilay Chakraborty, Apurva Borcar, Michael A. Menze, Mehmet Toner, Steven C. Hand
Late Embryogenesis Abundant Proteins Protect Human Hepatoma Cells During Acute Desiccation, Shumin Li, Nilay Chakraborty, Apurva Borcar, Michael A. Menze, Mehmet Toner, Steven C. Hand
Michael Menze
Expression of late embryogenesis abundant (LEA) proteins is highly correlated with desiccation tolerance in anhydrobiotic animals, selected land plants, and bacteria. Genes encoding two LEA proteins, one localized to the cytoplasm/nucleus (AfrLEA2) and one targeted to mitochondria (AfrLEA3m), were stably transfected into human HepG2 cells. A trehalose transporterwas used for intracellular loading of this disaccharide. Cellswere rapidly and uniformly desiccated to low water content (<0.12 g H2O/g dry weight) with a recently developed spin-drying technique. Immediately on rehydration, control cells without LEA proteins or trehalose exhibited 0% membrane integrity, comparedwith 98% in cells loaded with trehalose and expressing AfrLEA2 or AfrLEA3m; surprisingly, AfrLEA3m without trehalose conferred 94% protection. Cell proliferation across 7 d showed an 18-fold increase for cells dried with AfrLEA3m and trehalose, compared with 27-fold for nondried controls. LEA proteins dramatically enhance desiccation tolerance in mammalian cells and offer the opportunity for engineering biostability in the dried state.
Metabolic Preconditioning Of Mammalian Cells: Mimetic Agents For Hypoxia Lack Fidelity In Promoting Phosphorylation Of Pyruvate Dehydrogenase, Apurva Borcar, Michael A. Menze, Mehmet Toner, Steven C. Hand
Metabolic Preconditioning Of Mammalian Cells: Mimetic Agents For Hypoxia Lack Fidelity In Promoting Phosphorylation Of Pyruvate Dehydrogenase, Apurva Borcar, Michael A. Menze, Mehmet Toner, Steven C. Hand
Michael Menze
Induction of HIF-1α by oxygen limitation promotes increased phosphorylation and catalytic depression of mitochondrial pyruvate dehydrogenase (PDH) and an enhanced glycolytic poise in cells. Cobalt chloride and desferrioxamine are widely used as mimics for hypoxia because they increase the levels of HIF-1α. We evaluated the ability of these agents to elicit selected physiological responses to hypoxia as a means to metabolically precondition mammalian cells, but without the detrimental effects of hypoxia. We show that, while CoCl2 does increase HIF-1α in a dose-dependent manner, it unexpectedly and strikingly decreases PDH phosphorylation at E1α sites 1, 2, and 3 (Ser293, Ser300, and …
Long-Term Survival Of Anoxia Despite Rapid Atp Decline In Embryos Of The Annual Killifish Austrofundulus Limnaeus, Jason E. Podrabsky, Michael A. Menze, Steven C. Hand
Long-Term Survival Of Anoxia Despite Rapid Atp Decline In Embryos Of The Annual Killifish Austrofundulus Limnaeus, Jason E. Podrabsky, Michael A. Menze, Steven C. Hand
Michael Menze
Embryos of the annual killifish Austrofundulus limnaeus can survive for months in the complete absence of oxygen. Survival of anoxia is associated with entry into a state of metabolic dormancy known as diapause. However, extreme tolerance of anoxia is retained for several days of post-diapause development. Rates of heat dissipation in diapause II and 4 days post-diapause II embryos were measured under aerobic conditions and during the transition into anoxia. Phosphorylated adenylate compounds were quantified in embryos during entry into anoxia and after 12 hr of aerobic recovery. Rates of heat dissipation were not affected by exposure to anoxia in …
Trehalose Transporter From African Chironomid Larvae Improves Desiccation Tolerance Of Chinese Hamster Ovary Cells, Nilay Chakraborty, Michael A. Menze, Heidi Elmoazzen, Halong Vu, Martin Yarmush, Steven C. Hand, Mehmet Toner
Trehalose Transporter From African Chironomid Larvae Improves Desiccation Tolerance Of Chinese Hamster Ovary Cells, Nilay Chakraborty, Michael A. Menze, Heidi Elmoazzen, Halong Vu, Martin Yarmush, Steven C. Hand, Mehmet Toner
Michael Menze
Dry preservation has been explored as an energy-efficient alternative to cryopreservation, but the high sensitivity of mammalian cells to desiccation stress has been one of the major hurdles in storing cells in the desiccated state. An important strategy to reduce desiccation sensitivity involves use of the disaccharide trehalose. Trehalose is known to improve desiccation tolerance in mammalian cells when present on both sides of the cell membrane. Because trehalose is membrane impermeant the development of desiccation strategies involving this promising sugar is hindered. We explored the potential of using a high-capacity trehalose transporter (TRET1) from the African chironomid Polypedilum vanderplanki[21] …
Cryopreservation Of Spin-Dried Mammalian Cells, Nilay Chakraborty, Michael A. Menze, Jason Malsam, Alptekin Aksan, Steven C. Hand, Mehmet Toner
Cryopreservation Of Spin-Dried Mammalian Cells, Nilay Chakraborty, Michael A. Menze, Jason Malsam, Alptekin Aksan, Steven C. Hand, Mehmet Toner
Michael Menze
This study reports an alternative approach to achieve vitrification where cells are pre-desiccated prior to cooling to cryogenic temperatures for storage. Chinese Hamster Ovary (CHO) cells suspended in a trehalose solution were rapidly and uniformly desiccated to a low moisture content (<0.12 g of water per g of dry weight) using a spin-drying technique. Trehalose was also introduced into the cells using a high-capacity trehalose transporter (TRET1). Fourier Transform Infrared Spectroscopy (FTIR) was used to examine the uniformity of water concentration distribution in the spin-dried samples. 62% of the cells were shown to survive spin-drying in the presence of trehalose following immediate rehydration. The spin-dried samples were stored in liquid nitrogen (LN2) at a vitrified state. It was shown that following re-warming to room temperature and re-hydration with a fully complemented cell culture medium, 51% of the spin-dried and vitrified cells survived and demonstrated normal growth characteristics. Spin-drying is a novel strategy that can be used to improve cryopreservation outcome by promoting rapid vitrification.
Metabolic Restructuring During Energy-Limited States: Insights From Artemia Franciscana Embryos And Other Animals, Steven C. Hand, Michael A. Menze, Apu Borcar, Yuvraj Patil, Joseph A. Covi, Julie A. Reynolds, Mehmet Toner
Metabolic Restructuring During Energy-Limited States: Insights From Artemia Franciscana Embryos And Other Animals, Steven C. Hand, Michael A. Menze, Apu Borcar, Yuvraj Patil, Joseph A. Covi, Julie A. Reynolds, Mehmet Toner
Michael Menze
Many life history stages of animals that experience environmental insults enter developmental arrested states that are characterized by reduced cellular proliferation, with or without a concurrent reduction in overall metabolism. In the case of the most profound metabolic arrest reported in invertebrates, i.e., anaerobic quiescence in Artemia franciscana embryos, acidification of the intracellular milieu is a major factor governing catabolic and anabolic downregulation. Release of ion gradients from intracellular compartments is the source for approximately 50% of the proton equivalents needed for the 1.5 unit acidification that is observed. Recovery from the metabolic arrest requires re-sequestration of the protons with …
Lea Proteins During Water Stress: Not Just For Plants Anymore, Steven C. Hand, Michael A. Menze, Mehmet Toner, Leaf Boswell, Daniel Moore
Lea Proteins During Water Stress: Not Just For Plants Anymore, Steven C. Hand, Michael A. Menze, Mehmet Toner, Leaf Boswell, Daniel Moore
Michael Menze
Late embryogenesis abundant (LEA) proteins are extremely hydrophilic proteins that were first identified in land plants. Intracellular accumulation is tightly correlated with acquisition of desiccation tolerance, and data support their capacity to stabilize other proteins and membranes during drying, especially in the presence of sugars like trehalose. Exciting reports now show LEA proteins are not restricted to plants; multiple forms are expressed in desiccation-tolerant animals from at least four phyla. We evaluate here the expression, subcellular localization, biochemical properties and potential functions of LEA proteins in animal species during water stress. LEA proteins are intrinsically unstructured in aqueous solution, but …
Mechanisms Of Apoptosis In Crustacea: What Conditions Induce Versus Suppress Cell Death?, Michael A. Menze, Grady Fortner, Suman Nag, Steven C. Hand
Mechanisms Of Apoptosis In Crustacea: What Conditions Induce Versus Suppress Cell Death?, Michael A. Menze, Grady Fortner, Suman Nag, Steven C. Hand
Michael Menze
Arthropoda is the largest of all animal phyla and includes about 90% of extant species. Our knowledge about regulation of apoptosis in this phylum is largely based on findings for the fruit fly Drosophila melanogaster. Recent work with crustaceans shows that apoptotic proteins, and presumably mechanisms of cell death regulation, are more diverse in arthropods than appreciated based solely on the excellent work with fruit flies. Crustacean homologs exist for many major proteins in the apoptotic networks of mammals and D. melanogaster, but integration of these proteins into the physiology and pathophysiology of crustaceans is far from complete. Whether apoptosis …
Thermodynamics Of Effector Binding To Hemocyanin: Influence Of Temperature, Ariane Pott, Michael A. Menze, Manfred K. Grieshaber
Thermodynamics Of Effector Binding To Hemocyanin: Influence Of Temperature, Ariane Pott, Michael A. Menze, Manfred K. Grieshaber
Michael Menze
Hemocyanins are allosterically regulated oxygen carriers freely dissolved in the blood of many crustaceans. The natural modulator urate accumulates under hypoxic conditions in the hemolymph of Homarus vulgaris, and increases the oxygen affinity of the respiratory pigment. Other non-physiological effectors such as caffeine, dimethylxanthines and methylxanthines are also known to modulate the oxygen-binding properties of hemocyanin. In order to gain insight into the thermodynamic driving forces of these interactions we analyzed the binding of several urate analogs to dodecameric hemocyanin at different temperatures by employing isothermal titration calorimetry (ITC). All investigated non-physiological effectors including caffeine, dimethylxanthines and methylxanthines bind exothermically …
How Do Animal Mitochondria Tolerate Water Stress?, Michael A. Menze, Steven C. Hand
How Do Animal Mitochondria Tolerate Water Stress?, Michael A. Menze, Steven C. Hand
Michael Menze
The vast majority of animal species do not tolerate severe water stress, but the encysted embryo of the brine shrimp Artemia franciscana is an exceptionally useful organism to investigate physiological mechanisms for enduring extreme environmental insults. Any substantial reduction in cellular water poses a threat to survival. Nevertheless anhydrobiotic animals survive virtually complete loss of cellular water. The mechanisms that govern “life without water” (anhydrobiosis) are still not well understood. With certain exceptions, it seems that a recurring strategy for tolerating severe water loss involves the accumulation of both low molecular weight solutes (e.g. trehalose or other polyol) and highly …
Mitochondria In Energy-Limited States: Mechanisms That Blunt The Signaling Of Cell Death, Steven C. Hand, Michael A. Menze
Mitochondria In Energy-Limited States: Mechanisms That Blunt The Signaling Of Cell Death, Steven C. Hand, Michael A. Menze
Michael Menze
Cellular conditions experienced during energy-limited states – elevated calcium, shifts in cellular adenylate status, compromised mitochondrial membrane potential – are precisely those that trigger, at least in mammals, the mitochondrion to initiate opening of the permeability transition pore, to assemble additional protein release channels, and to release pro-apoptotic factors. These proapototic factors in turn activate initiator and executer caspases. How is activation of mitochondria-based pathways for the signaling of apoptotic and necrotic cell death avoided under conditions of hypoxia, anoxia, diapause, estivation and anhydrobiosis? Functional trade-offs in environmental tolerance may have occurred in parallel with the evolution of diversified pathways …
Dessication Stress, Steven C. Hand, Michael A. Menze
Dessication Stress, Steven C. Hand, Michael A. Menze
Michael Menze
The threat of desiccation for organisms inhabiting the intertidal zone occurs during emersion at low tides or when organisms are positioned in the high intertidal zone, where wetting occurs primarily by spring tides, storm waves, and spray. Drying due to evaporative water loss is the most common mechanism for dehydration, although during winter in northern temperate regions freezing can also occur, which reduces the liquid water in extracellular fluids and can lead to intracellular dehydration in multicellular organisms. Freezing tolerance has been reported and characterized for a number of intertidal invertebrates, including gastropods such as an air-breathing snail and a …
Life Without Water: Expression Of Plant Lea Genes By An Anhydrobiotic Arthropod, Steven C. Hand, Dana Jones, Michael A. Menze, Trudy L. Witt
Life Without Water: Expression Of Plant Lea Genes By An Anhydrobiotic Arthropod, Steven C. Hand, Dana Jones, Michael A. Menze, Trudy L. Witt
Michael Menze
Anhydrobiotic animals protect cellular architecture and metabolic machinery in the dry state, yet the molecular repertoire supporting this profound dehydration tolerance is not fully understood. For the desiccation-tolerant crustacean, Artemia franciscana, we report differential expression of two distinct mRNAs encoding for proteins that share sequence similarities and structural features with late-embryogenesis abundant (LEA) proteins originally discovered in plants. Bioinformatic analyses support assignment of the LEA proteins from A. franciscana to group 3. This eucoelomate species is the most highly evolved animal for which LEA gene expression has been reported. It is becoming clear that an ensemble of micromolecules and macromolecules …
Trehalose Uptake Through P2x7 Purinergic Channels Provides Dehydration Protection, Gloria D. Elliott, Jennifer L. Cusick, Xiang-Hong Liu, Michael A. Menze, Trudy Witt, Steven C. Hand, Mehmet Toner
Trehalose Uptake Through P2x7 Purinergic Channels Provides Dehydration Protection, Gloria D. Elliott, Jennifer L. Cusick, Xiang-Hong Liu, Michael A. Menze, Trudy Witt, Steven C. Hand, Mehmet Toner
Michael Menze
The tetra-anionic form of ATP (ATP4-) is known to induce monovalent and divalent ion fluxes in cells that express purinergic P2X7 receptors (Steinberg et al., 1987; Sung et al., 1985), and with sustained application of ATP it has been shown that dyes as large as 831 daltons can permeate the cell membrane (Steinberg et al, 1987). The current study explores the kinetics of loading α,α-trehalose (342 daltons) into ATP stimulated J774.A1 cells, which are known to express the purinergic P2X7 receptor (Steinberg et al., 1987). Cells that were incubated at 37 ̊C in a 50 mM phosphate buffer (pH 7.0) …
Cryopreservation Of Human Hematopoietic Stem And Progenitor Cells Loaded With Trehalose: Transient Permeabilization Via The Adenosine Triphosphatedependent P2z Receptor Channel, Sandhya S. Buchanan, Michael A. Menze, Steven C. Hand, David W. Pyatt, John F. Carpenter
Cryopreservation Of Human Hematopoietic Stem And Progenitor Cells Loaded With Trehalose: Transient Permeabilization Via The Adenosine Triphosphatedependent P2z Receptor Channel, Sandhya S. Buchanan, Michael A. Menze, Steven C. Hand, David W. Pyatt, John F. Carpenter
Michael Menze
Hematopoietic stem and progenitor cells (HPCs) are a heterogenic population of cells used to treat a number of human diseases. Multilineage differentiation is a required function in successful hematopoietic reconstitution after transplantation of cryopreserved grafts. Conventional use of the cryoprotectant dimethyl sulfoxide (DMSO) has resulted in some reports of infusion related toxicity attributed to DMSO and/or damage to cells during freezethawing procedures. The purpose of this study was to explore the use of trehalose, a nontoxic disaccharide of glucose, as an alternative cryoprotectant. Trehalose was introduced into HPCs using the P2Z receptor, known to form nonselective pores in the presence …
Allosteric Models For Multimeric Proteins: Oxygen-Linked Effector Binding In Hemocyanin, Michael A. Menze, Nadja Hellman, Heinz Decker, Manfred K. Grieshaber
Allosteric Models For Multimeric Proteins: Oxygen-Linked Effector Binding In Hemocyanin, Michael A. Menze, Nadja Hellman, Heinz Decker, Manfred K. Grieshaber
Michael Menze
In many crustaceans, changing concentrations of several low molecular weight compounds modulates hemocyanin oxygen binding, resulting in lower or higher oxygen affinities of the pigment. The nonphysiological effector caffeine and the physiological modulator urate, the latter accumulating in the hemolymph of the lobster Homarus Vulgaris during hypoxia, increase hemocyanin oxygen affinity and decrease cooperativity of oxygen binding. To derive a model that describes the mechanism of allosteric interaction between hemocyanin and oxygen in the presence of urate or caffeine, studies of oxygen, urate, and caffeine binding to hemocyanin were performed. Exposure of lobster hemocyanin to various pH values between 7.25 …
Trehalose Loading Through The Mitochondrial Permeability Transition Pore Enhances Desiccation Tolerance In Rat Liver Mitochondria, Xiang-Hong Liu, Alptekin Aksan, Michael A. Menze, Steven C. Hand, Mehmet Toner
Trehalose Loading Through The Mitochondrial Permeability Transition Pore Enhances Desiccation Tolerance In Rat Liver Mitochondria, Xiang-Hong Liu, Alptekin Aksan, Michael A. Menze, Steven C. Hand, Mehmet Toner
Michael Menze
Trehalose has extensively been used to improve the desiccation tolerance of mammalian cells. To test whether trehalose improves desiccation tolerance of mammalian mitochondria, we introduced trehalose into the matrix of isolated rat liver mitochondria by reversibly permeabilizing the inner membrane using the mitochondrial permeability transition pore (MPTP). Measurement of the trehalose concentration inside mitochondria using high perfOrmance liquid chromatography showed that the sugar permeated rapidly into the matrix upon opening the MPTP. The concentration of intra matrix trehalose reached 0.29 mmoVmg protein (-190 mM) in 5 min. Mitochondria, with and without trehalose loaded into the matrix, were desiccated in a …
Binding Of Urate And Caffeine To Hemocyanin Analyzed By Isothermal Titration Calorimetry, Michael A. Menze, Nadja Hellmann, Heinz Decker, Manfred K. Grieshaber
Binding Of Urate And Caffeine To Hemocyanin Analyzed By Isothermal Titration Calorimetry, Michael A. Menze, Nadja Hellmann, Heinz Decker, Manfred K. Grieshaber
Michael Menze
Haemocyanin serves as an oxygen carrier in the haemolymph of decapod crustaceans. The oxygen-binding behaviour of the pigment is modulated by the two major anaerobic metabolites, L-lactate and urate. The binding of these two metabolites to haemocyanin has been investigated mainly indirectly by following the effectorinduced changes in the oxygen-binding properties of the respiratory pigment. Only a few direct investigations of effector binding, employing ultracentrifugation techniques and equilibrium dialysis, have been carried out. No evidence for cooperative binding for either effector was detected using these methods. However, isothermal titration calorimetry (ITC) offers a useful tool to gain additional insight into …
Binding Of Urate And Caffeine To Hemocyanin Of The Lobster Homarus Vulgaris (E.) As Studied By Isothermal Titration Calorimetry †, Michael A. Menze, Nadja Hellmann, Heinz Decker, Manfred K. Grieshaber
Binding Of Urate And Caffeine To Hemocyanin Of The Lobster Homarus Vulgaris (E.) As Studied By Isothermal Titration Calorimetry †, Michael A. Menze, Nadja Hellmann, Heinz Decker, Manfred K. Grieshaber
Michael Menze
Hemocyanin serves as an oxygen carrier in the hemolymph of the European lobster Homarus Vulgaris. The oxygen binding behavior of the pigment is modulated by metabolic effectors such as lactate and urate. Urate and caffeine binding to 12-meric hemocyanin (H. Vulgaris) was studied using isothermal titration calorimetry (ITC). Binding isotherms were determined for fully oxygenated hemocyanin between pH 7.55 and 8.15. No pH dependence of the binding parameters could be found for either effector. Since the magnitude of the Bohr effect depends on the urate concentration, the absence of any pH dependence of urate and caffeine binding to oxygenated hemocyanin …