Transport in plants .III. Intracellular interactions and transport processes.

The problems associated with the movement of water and solutes throughout the plant body have intrigued students of plants since Malpighi's conclusions in 1675 and 1679 that nutrient sap flows upward and downward in stems through vessels in both wood and bark. Steven Hale's ingenious experiments on the movement of water in plants in 1726 and Hartig's observations of sieve-tube exudation in the mid-19th century set the stage for continued intensive studies on long-range transport in plants. In spite of this interest for more than 200 years in the movement of solutes and water in plants, it has only been within the last 20 to 30 years that extensive research effort has been directed toward a critical evaluation of the interactions among the various cellular organelles. The important roles played by the exchange of metabolites in the control and regulation of cellular processes is now widely recognized, but in most instances poorly understood.

I. Membrane Structure.- Plant Membranes.- 1. Introduction.- 2. Isolation of Membranes.- 2.1 Choice of Tissue.- 2.2 Identification of Specific Membranes.- 2.2.1 Microscopy.- 2.2.2 Histochemical Staining.- 2.2.3 Marker Enzymes.- 2.2.4 Antibodies.- 2.3 Tissue Disruption.- 2.4 Membrane Isolation.- 3. Membrane Composition.- 3.1 Membrane Carbohydrates.- 3.2 Membrane Lipids.- 3.3 Membrane Proteins.- 4. Specific Membranes.- 4.1 The Plasmalemma (Plasma Membrane).- 4.1.1 Morphology.- 4.1.2 Chemical Composition.- 4.2 The Nuclear Envelope.- 4.2.1 Morphology.- 4.2.2 Chemical Composition.- 4.3 Plastid Membranes.- 4.3.1 Morphology.- 4.3.1.1 General.- 4.3.1.2 Proplastids.- 4.3.1.3 Etioplasts.- 4.3.1.4 Amyloplasts.- 4.3.1.5 Chromoplasts.- 4.3.1.6 The Higher Plant Chloroplasts.- 4.3.2 Chemical Composition of the Chloroplast Envelope.- 4.4 Mitochondrial Membranes.- 4.4.1 Morphology.- 4.4.2 Chemical Composition.- 4.5 Other Membranes in Plant Cells.- 4.5.1 The Microbody Membrane.- 4.5.2 The Endoplasmic Reticulum Membranes.- 4.5.3 The Golgi Apparatus Membranes.- 4.5.4 The Vacuolar Membrane.- 4.5.5 The Spherosome Membrane.- 5. Membrane Models.- 5.1 The Lipid Bilayer Model.- 5.2 The Unit Membrane Model.- 5.3 Subunit Models.- 5.4 The Lipid-Globular Protein Mosaic Model.- 6. Membrane Structure and Solute Transport.- 6.1 Membranes with Hydrophilic Pores.- 6.2 Carriers and Ionophores.- 6.3 Bridging Proteins Acting as Channels through Membranes.- References.- II. Intracellular Interactions.- 1. Interactions between Nucleus and Cytoplasm.- 1. Old Theories and Present Ideas about the Biochemical Role of the Cell Nucleus.- 2. Experimental Approaches to the Study of Nucleocytoplasmic Interactions.- 2.1 Work on Intact Cells.- 2.1.1 Autoradiography.- 2.1.2 Studies on Chromatin and DNA in Intact Cells.- 2.2 Work on Anucleate Fragments of Unicellular Organisms, Eggs, and Cells.- 2.3 Biochemical Work on Isolated Organelles.- 3. Discussion of Some Recent Experimental Results.- 3.1 Work on Intact Cells.- 3.1.1 Autoradiography.- 3.1.2 Role of the Nuclear Membrane in Nucleocytoplasmic Interactions.- 3.1.3 Choice by the Cytoplasm between DNA Replication and Transcription.- 3.1.4 Effects of the Plasma Membrane on Nuclear Activity.- 3.2 Studies on Anucleate Fragments of Unicellular Organisms, Eggs, and Cells.- 3.2.1 Acetabularia.- 3.2.1.1 Introduction.- 3.2.1.2 Production and Distribution of Morphogenetic Substances.- 3.2.1.3 Energy Production, Circadian Rhythms.- 3.2.1.4 Chloroplastic and Cytoplasmic Protein Synthesis.- 3.2.1.5 Nucleic Acid Synthesis.- 3.2.1.6 Cytoplasmic Effects on the Nucleus.- 3.2.2 Protozoa.- 3.2.3 Eggs.- 3.2.3.1 Sea Urchin Eggs.- 3.2.3.2 Other Eggs.- 3.2.4 Mammalian Cells.- 3.2.4.1 Reticulocytes.- 3.2.4.2 Cells Enucleated with Cytochalasin B.- 4. Conclusions.- References.- 2. Plastids and Intracellular Transport.- 1. Introduction.- 2. The Development of the Experimental Study of Metabolite Translocation in Chloroplasts.- 3. Methods.- 3.1 Distribution in vivo.- 3.1.1 Nonaqueous Techniques.- 3.1.2 Aqueous Separation.- 3.2 Distribution in vitro.- 3.2.1 Centrifugal Filtration.- 3.2.2 Chromatographic Analysis.- 3.3 Indirect Methods.- 3.3.1 Shortening of Induction and Reversal of Orthophosphate Inhibition.- 3.3.2 Catalysis by Intact and Ruptured Chloroplasts.- 3.3.3 Osmotic Volume Changes.- 3.4 Other Aspects of Work with Functional Chloroplasts.- 4. The Site of Sucrose Synthesis.- 5. Starch Synthesis.- 6. The Stimulation of Starch Synthesis in the Light by Exogenous Sugars.- 7. Starch Prints.- 8. The Transport of Metabolites and Coenzymes.- 9. The Transport of Cycle Intermediates.- 9.1 3-Phosphoglycerate and the Triose Phosphates.- 9.2 Pentose Monophosphates.- 9.3 Hexose and Heptose Monophosphates.- 9.4 Sugar Bisphosphates.- 9.4.1 Ribulose-l,5-bisphosphate (RBP).- 9.4.2 Fructose-1,6-bisphosphate(FBP) and Sedoheptulose-l,7-bisphosphate(SBP).- 10. Free Sugars.- 11. C02/Bicarbonate.- 12. Carboxylic Acids.- 12.1 Glycollate and Glyoxylate.- 12.2 Malate and Oxaloacetate.- 13. Amino Acids.- 14. Orthophosphate.- 15. Inorganic Pyrophosphate.- 16. ADP and ATP.- 16.1 Direct Transfer.- 16.2 The Evidence in Favour of Rapid Direct Transfer.- 16.3 The Evidence against Rapid Direct Transfer.- 17. NADP.- 18. Shuttles.- 18.1 The PGA/DHAP Shuttle.- 18.2 The Malate/Oxaloacetate Shuttle.- 19. Specific Transport.- 19.1 ATP Transport.- 19.2 Dicarboxylate Transport.- 19.3 Phosphate Transport.- 20. The Movement of Metabolites in C4 Photosynthesis.- 21. The Movement of Protons and Magnesium.- 22. Concluding Remarks.- References.- 3. Metabolite Carriers of Chloroplasts.- 1. Specific Transport into the Chloroplast.- 2. The Phosphate Translocator.- 3. The Dicarboxylate Translocator.- 4. ATP Transport in Chloroplasts.- References.- 4. Compartmentation and Transport in C4 Photosynthesis.- 1. Introduction.- 2. Radiotracer Kinetics and Compartments.- 3. Inter- and Intracellular Compartmentation of Reactions.- 3.1 Methods.- 3.2 Activities of Isolated Mesophyll and Bundle Sheath Cells.- 3.3 C4 Pathway Enzymes and Their Intercellular Distribution.- 3.4 Intracellular Location of Enzymes.- 3.5 Detailed Schemes for C4 Photosynthesis.- 4. Intercellular Transport in C4 Photosynthesis.- 4.1 Structural Features of the Mesophyll-Bundle Sheath Cell Interface.- 4.2 Intercellular Transport of Metabolite Solutes.- 4.3 Intercellular Transport of CO2 + HCO3?: the CO2 Concentrating Mechanism.- 4.4 Amino Group and Charge Balance during Intercellular Transport.- 5. Intracellular Transport in C4 Photosynthesis.- 5.1 Intracellular Transport in Mesophyll Cells.- 5.2 Intracellular Transport in Bundle Sheath Cells.- 5.3 Organelle Ultrastructure in Relation to Intracellular Transport.- 6. Metabolite Transport in Relation to Chloroplast Photochemical Activities.- 7. Physiological Function of Compartmentation and Transport in C4 Photosynthesis.- References.- 5. Interactions among Organelles Involved in Photorespiration.- 1. Introduction.- 2. Methodology.- 2.1 Measurement of Photorespiration.- 2.1.1 Definitions.- 2.1.2 CO2 Gas Exchange.- 2.1.3 Estimates of Photorespiration by Leaf Models.- 2.1.4 Estimates of Carbon Flux through the Glycolate Pathway.- 2.2 Isolation of Leaf Peroxisomes and Other Cell Organelles.- 3. Glycolate Metabolism and Its Intracellular Compartmentation.- 3.1 Biosynthesis of Glycolate in Chloroplasts.- 3.2 The Glycolate Pathway and Peroxisomes.- 3.3 The Interconversion of Glycine and Serine in the Mitochondria.- 3.4 Glycerate and Its Relationship to Phosphoglycerate.- 4. Glycolate Metabolism in C4-plants, CAM Plants, and Algae.- 4.1 Glycolate Metabolism in C4-plants.- 4.2 Glycolate Metabolism in CAM Plants.- 4.3 Glycolate Metabolism in Algae.- 4.4 Glycolate Metabolism in Blue-Green Algae.- 5. The Transport of Metabolites between Cell Organelles during Glycolate Metabolism.- 5.1 Transport of Glycolate Pathway Intermediates between Peroxisomes, Chloroplasts, and Mitochondria.- 5.2 Sites of CO2 Evolution and O2 Uptake during Photorespiration.- 5.3 Insignificance of the Glycolate-Glyoxylate Shuttle.- 5.4 The Malate-Aspartate Shuttle.- 6. The Magnitude of Photorespiration with Respect to the Glycolate Pathway Metabolism and Metabolite Transfer.- 6.1 Gas Exchange.- 6.1.1 Effects of Oxygen and Carbon Dioxide.- 6.1.2 Effects of Light and Temperature.- 6.1.3 Effects of External Factors on the Gas Exchange of C4-plants.- 6.1.4 The Specific Activity of the 14CO2 Evolved in the Light and in the Dark.- 6.2 Carbon Flux through the Glycolate Pathway.- 6.2.1 C3-plants in Air.- 6.2.2 C3-plants in a Medium with Low Oxygen.- 6.2.3 C4-plants in Normal and Low Oxygen.- 6.2.4 Carbon Fluxes and Enzyme Activities.- 6.3 The Function of Light Respiration.- 7. Concluding Remarks.- References.- 6. Transport of Metabolites between Cytoplasm and the Mitochondrial Matr.- 1. Introduction.- 2. Structure of Mitochondria.- 3. Functional Organization of Mitochondrial Metabolism.- 4. Transport of Adenine Nucleotides.- 5. Transport of Inorganic Phosphate.- 6. Transport of the Intermediates of the Tricarboxylic Acid Cycle.- 7. Transport of Glutamate and Aspartate.- 8. Transport of Pyruvate.- 9. Transport of Phosphate and of Carboxylates in Plant Mitochondria.- 10. Uptake of Fatty Acids.- 11. Oxidation of Extramitochondrial NADH by Mitochondria.- 12. On a Possible Role of Mitochondrial Transport in Lipogenesis.- 13. Conclusion.- References.- 7. Interactions between Cytoplasm and Vacuole.- 1. Introduction.- 2. Vacuoles as Repositories of Substances.- 2.1 The Internal Environment of the Cytoplasm.- 2.2 Methods Used for Evaluating Vacuolar Compartmentation of Substances.- 2.2.1 Isolation of Vacuoles.- 2.2.2 Stepwise Extraction of Cells.- 2.2.3 Indirect Evidence from Isotope Kinetics.- 2.2.4 Electron Microscopy, Autoradiography, Electron Microprobe.- 2.2.5 Direct Microscopic Observations.- 2.3 Substances Present in Vacuoles.- 2.3.1 Metabolic Intermediates.- 2.3.2 Reserve Substances.- 2.3.3 Secondary Product of Metabolism.- 2.3.4 Inorganic Substances.- 2.4 Mechanisms of Transport in Vacuoles.- 2.4.1 Transport of Ions.- 2.4.2 Accumulation of Products of Secondary Metabolism.- 3. Vacuoles as Digestive Compartments.- 3.1 Hydrolases Localized in Vacuoles.- 3.1.1 Remarks on Methods Employed.- 3.1.2 Vacuoles as Lysosomes.- 3.2 Autophagy.- 3.2.1 Turnover.- 3.2.2 Mechanisms of Autophagy.- 3.2.3 Heterophagy.- 3.2.4 Autolysis.- 3.2.5 Digestive Processes in Plant Development.- 4. Concluding Remarks.- References.- 8. Interactions among Cytoplasm, Endomembranes, and the Cell Surface.- 1. Introduction.- 2. Cell Surfaces and Expansion Growth.- 3. Role of the Soluble Cytoplasm (Cytosol).- 3.1 Biosynthetic Role of the Cytosol.- 3.2 Guide Elements of the Cytosol.- 3.3 Milieu for Biosynthesis and Transformation (Zones of Exclusion).- 4. Role of Internal Membranes.- 4.1 Role in the Biosynthesis, Assembly, Transformation, and Transport of Membranes.- 4.1.1 The Endomembrane System.- 4.1.2 Membrane Differentiation.- 4.1.3 Membrane Flow.- 4.2 Role in the Biosynthesis, Assembly, Transformation, and Transport of Products for Secretion to the Cell’s Exterior.- 4.2.1 Cell Walls.- 4.2.2 Slimes and Mucilages.- 4.2.3 Essential Oils.- 4.2.4 Encrusting Materials.- 4.2.5 Dilute Secretions Containing Lipids, Sugars, Mucilages, and Salts.- 4.2.6 Digestive Enzymes.- 4.2.7 Water Expulsion.- 4.3 Role in the Biosynthesis, Assembly, Transformation, and Transport of Products among Internal Compartments.- 4.3.1 Vacuoles.- 4.3.2 Vacuole Membranes.- 4.3.3 Vacuole Contents.- 5. Role of the Cell Surface.- 5.1 Role of the Plasma Membrane in Cell Wall Formation.- 5.2 Plasmodesmata.- 5.3 Role of Cell Walls in Cell Wall Formation.- 6. Specializations in the Formation of Plant Cell Surfaces.- 7. Summary.- References.- III. Intracellular Transport in Relation to Energy Conservation.- 1. Ion Transport and Energy Conservation in Chloroplasts.- 1. Introduction.- 2. Mechanisms of H+ Uptake in Chloroplasts.- 2.1 H+ Uptake in the Absence of Permeating Electron Donors or Acceptors.- 2.2 H+ Uptake in the Presence of Permeating Electron Donors or Acceptors.- 3. Counter Ion Fluxes.- 4. The Magnitude of the Electrochemical Gradient.- 4.1 The H+ Concentration Gradient.- 4.2 The Membrane Potential.- 5. Relation of H+ Movements to Phosphorylation.- 6. Relation of the Rate of Electron Flow to H+ Movements.- 7. Conclusion.- References.- 2. Ion Transport in Plant Mitochondria.- 1. Introduction.- 2. Monovalent Salt Transport.- 2.1 Monovalent Cation and Anion Transport in Plant Mitochondria.- 2.2 Chemiosmotic Theory of Ion Transport.- 2.3 Mechanism of Salt Flux.- 2.4 Monovalent Cation Transport with Ionophorous Antibiotics.- 2.5 Substrate Transport into Mitochondria.- 3. Divalent Cation Transport.- 3.1 Divalent Cation Transport in Plant Mitochondria.- 3.2 Theories of Ca2+ Transport in Animal Mitochondria.- 3.3 Regulation of Ca2+ Flux.- 3.4 Role for Mitochondria in the Transport and Regulation of Ca2+.- References.- 3. Energy Transfer between Cell Compartments.- 1. Introduction.- 2. Exchange of Energy between Mitochondria and Cytoplasm.- 3. Exchange of Energy between Chloroplasts and Cytoplasm.- 3.1 Evidence for Energy Exchange between Chloroplasts and Cytoplasm.- 3.1.1 Active Uptake of Sugars and Ions.- 3.1.2 Transient Changes of Intracellular Adenine Nucleotide Levels.- 3.2 Direct Translocation of Adenine Nucleotides across the Chloroplast Envelope via Adenine Nucleotide Translocator.- 3.3 Indirect Transport of Energy across the Chloroplast Envelope via Shuttle Systems.- 4. Conclusion.- References.- IV. Theory of Membrane Transport.- Mass Transport across Membranes.- 1. Nonequilibrium Thermodynamics of Membrane Transport.- 1. 1 Introduction.- 1.2 Transport of Nonelectrolytes.- 1.2.1 Description of the Membrane System.- 1.2.2 Entropy Balance.- 1.2.3 Energy Balance.- 1.2.4 Mass Balance.- 1.2.5 Entropy Production.- 1.2.6 Linear Laws.- 1.2.7 Linear Laws for Dilute Solutions.- 1.2.8 Influence of Nonpermeable Components.- 1.3 Transport of Nonelectrolytes with Chemical Reaction.- 1.3.1 Description of the Membrane System.- 1.3.2 Mass Balance.- 1.3.3 Entropy Production.- 1.3.4 Linear Laws.- 1.3.5 Active Transport.- 1.4 Transport of Electrolytes.- 1.4.1 Description of the Membrane System.- 1.4.2 Entropy Balance.- 1.4.3 Energy Balance.- 1.4.4 Mass Balance.- 1.4.5 Entropy Production.- 1.4.6 Generalization.- 1.4.7 Linear Laws for Dilute Solutions; Special Case.- 1.5 Summary.- 2. Transport Processes across Membranes with Narrow Pores.- 2.1 Introduction.- 2.2 Transport Equations.- 2.3 Equilibrium at the Phase Boundary Membrane/Solution.- 2.4 Integration of the Transport Equations.- 2.4.1 Bulk Phases of Equal Composition.- 2.4.1.1 Electroosmotic Volume Flow.- 2.4.1.2 Electric Conductivity.- 2.4.1.3 Electric Transference.- 2.4.1.4 Streaming Potential.- 2.4.2 Bulk Phases of Different Composition.- 2.4.2.1 Approximate Integration of the Transport Equations (Constant Field Assumption).- 2.4.2.2 Unidirectional Flows and Flow Ratio.- 2.4.2.3 Membrane Potential.- 2.4.2.4 Osmotic Properties.- 2.5 Summary.- List of Symbols.- References.- Author Index.