Chemotaxis

Contents......Page 8
1. Introduction......Page 18
References......Page 21
1. Introduction......Page 24
2.1. Active swimming by means of flagella and cilia......Page 27
2.2. Swarming movements......Page 28
2.3. Gliding and twitching movements......Page 29
2.4. Crawling and amoeboid movements......Page 30
2.5. Problems related to nomenclature......Page 31
3. The Physiological Role of Chemotaxis: Sensory Aspects......Page 32
3.1.1. Chemosensing and metabolic activities are coupled......Page 33
3.1.2. Cellular energy levels are central in chemosensing......Page 35
3.1.3. Cellular sensors are variable in structure......Page 37
3.1.4. The role of protein synthesis in chemosensing and learning......Page 38
3.2. Chemotaxis among eukaryotic organisms......Page 39
3.2.1. The importance of model organisms......Page 40
3.2.2. Primitive eukaryotic groups showing true chemotaxis......Page 41
4. The Role of Chemotaxis in Fertilization and Reproduction......Page 45
4.1. The role of chemotaxis in fertilization......Page 46
4.2. The role of gamones in the brown algae and in fungi......Page 47
4.3. The role of gamones in the archegoniata......Page 48
4.5. Relations to other eukaryotic chemosensory systems......Page 51
5.1. Problems related to tests in natural habitats......Page 53
5.2. Cooperative consortia, biofilms, and other associations......Page 54
5.3. Microbial associations in natural habitats......Page 56
6. The Role of Chemotaxis in Differentiation Processes of Multicellular Organisms......Page 58
6.1. The cytoskeleton is central in amoeboid crawling movements......Page 59
6.2. Physical guidance must not be confused with chemotaxis......Page 60
6.3. Model systems to analyze motility in differentiation processes......Page 61
7. Conclusions......Page 64
References......Page 65
1. Introduction......Page 70
2.1.1. Flagellar motility......Page 71
2.1.2. “Swimming” without flagella......Page 74
2.1.3. Gliding motility......Page 75
2.1.4. Twitching motility......Page 77
2.2. Bacterial flagella......Page 78
2.2.1. Structure of flagella......Page 80
2.2.2. Genes involved in motility......Page 83
2.2.4. The energy source of flagellar rotation......Page 88
2.2.5. The flagellar motor......Page 90
2.2.6. The flagellar switch......Page 94
2.2.7. Assembly of flagella......Page 97
2.3.1. Swimming in the absence of chemotactic stimuli......Page 101
2.3.2. Swimming in a gradient of a chemotactic stimulus......Page 103
2.4. The gradient sensed by bacteria: temporal vs. spatial......Page 104
2.5. Excitation and adaptation......Page 106
3.1.1. Capillary assay......Page 107
3.1.2. Chemical-in-plug assay......Page 110
3.1.5. Diffusion gradient over a membrane......Page 111
3.3. Ring forming assay on semisolid agar......Page 112
3.4.1. Three-dimensional tracking......Page 114
3.5.1. Tethering assay......Page 115
3.5.2. Visualization of functional flagella......Page 116
3.5.3. Chi phage assay......Page 117
4.1. Types of stimuli......Page 118
4.2. General characteristics of stimuli......Page 120
4.3. Diversity of stimuli in different species......Page 121
4.4. Are the stimuli themselves detected or their metabolic products?......Page 122
5. Chemotaxis-Related Genes......Page 126
6.1. Chemotaxis-specific receptors......Page 130
6.1.1. Structure of the MCPs......Page 131
6.1.2. Functions of the MCPs and structure-function relationship......Page 133
6.1.3. Receptor clustering......Page 136
6.1.4. MCPs in species other than E. coli and Salmonella......Page 139
6.2. Dual-function receptors......Page 140
6.2.1. Periplasmic binding proteins......Page 141
6.3. Chemorepellent receptors......Page 142
7.1.2. Structure of CheA......Page 144
7.1.4. CheA in species other than E. coli and Salmonella......Page 146
7.2. CheB......Page 147
7.4. CheW......Page 149
7.5.1. Function of CheY......Page 151
7.5.2. Structure of CheY......Page 156
7.5.3. Active CheY mutants and analogs......Page 158
7.6. CheZ......Page 160
8.2. Mechanism of excitation......Page 164
8.2.2. CheY is the clockwise signal......Page 165
8.2.3. Regulation of CheY activity......Page 166
8.2.4. Mechanism of switching......Page 167
8.2.5. Sequence of events......Page 168
8.2.6. Coordinating signals of different intensity......Page 169
8.2.7. Signal amplification......Page 171
8.2.8. Variations on excitatory signal transduction in E. coli......Page 172
8.2.9. Some open questions......Page 174
8.3.1. Involvement of MCP methylation in adaptation......Page 176
8.3.2. The signal for adaptation......Page 178
8.3.4. Methylation-independent adaptation......Page 179
8.4. A nonconventional signal transduction pathway in E. coli......Page 180
8.5.1. More than one signal transduction pathway......Page 181
8.5.2. Lack of CheZ......Page 182
8.5.4. Different inputs......Page 184
References......Page 185
1. Introduction......Page 233
2.1. Pattern formation in minimal medium and the role of the Tar receptor......Page 234
2.3. A potential biological role for pattern formation in E. coli and Salmonella......Page 237
3.1. Swarming motility......Page 238
3.2. Intercellular signaling and swarming......Page 239
4.1. Paenibacillus dendritiformis morphotypes......Page 241
4.3. Morphotype “nebula”......Page 243
4.4. Mutants of P. dendritiformis defective in pattern formation: phenotypes and reconstitution......Page 244
5.1. Introduction to the myxobacteria......Page 247
5.2. Direct evidence for chemotaxis......Page 251
5.3.1. The Frz system......Page 254
5.3.2. The Dif system......Page 256
5.3.3. Other chemotaxis gene clusters......Page 257
5.4. The role of intercellular signaling in development......Page 258
5.4.3. C-signal......Page 259
6. Concluding Remarks......Page 261
References......Page 262
1. Introduction......Page 270
1.1. Functions of amoeboid chemotaxis......Page 271
2. Amoeboid Motility......Page 273
2.1.1. Extension......Page 274
2.1.2. Adhesion......Page 277
2.1.3. Contraction......Page 278
2.2. The cytoskeleton......Page 279
2.2.1. Actin and myosin......Page 280
2.3. Adhesion......Page 284
2.3.2. Focal contacts......Page 285
2.4. The gradient sensed by amoebae: temporal vs. spatial sensing......Page 287
2.5. Excitation and adaptation......Page 289
3. Techniques to Measure Motility and Chemotaxis......Page 290
3.1.1. Micropipet assay......Page 291
3.1.4. Agar assays......Page 292
3.2.1. Actin polymerization assays......Page 293
3.3. Tracking amoebae in situ......Page 294
4.1.1. Molecular mechanisms of Dictyostelium chemotaxis......Page 295
4.1.3. The phosphoinositide 3-kinase pathway......Page 296
4.1.4. Other pathways......Page 302
4.2.1. Receptors......Page 304
4.2.2. Receptor coupling to intracellular pathways......Page 305
4.2.3. Stimulation of extension......Page 306
4.2.4. Adhesion......Page 307
4.2.6. Negative feedback......Page 308
4.2.7. Integration mechanisms for spatial gradient sensing......Page 309
5. Conclusion......Page 310
References......Page 311
1. Introduction......Page 325
2. Neutrophil Chemoattractants......Page 326
3. The Transition from Circulating to Migrating Cells......Page 327
4.1. Overview......Page 332
4.2.1. Indirect assays......Page 334
4.2.2. Population-based assays......Page 338
4.2.3. Single cell tracking assays and analysis......Page 342
5. Cell Polarization......Page 345
5.1.2. Cells in a chemoattractant gradient......Page 346
5.2. Molecular aspects of polarization......Page 348
5.3. Development of polarity......Page 349
6.1. Migration on a two-dimensional surface......Page 351
6.2. Migration in a three-dimensional matrix......Page 352
7.1.1. The case for actin polymerization......Page 353
7.1.3. Is myosin important for lamellipodium formation?......Page 354
7.3. Rear retraction......Page 355
8.2. Multiple chemoattractants......Page 356
9. Signal Transduction......Page 357
9.1. Ligand-receptor binding and processing......Page 358
9.1.2. The nature of LRx......Page 359
9.1.3. Relationship of receptor states in intact neutrophils and reconstituted systems......Page 361
9.1.4. Receptor internalization and recycling......Page 362
9.1.5. Global inhibition and local activation hypothesis of signaling in the lamellipodium......Page 363
9.2. Heterotrimeric G-proteins......Page 364
9.2.1. The G-protein cycle......Page 365
9.2.2. Precoupled receptor/G-protein complexes......Page 366
9.3.1. Phosphatidylinositol 3-kinase......Page 368
9.3.2. Small GTP-binding proteins and regulation of neutrophil chemotaxis......Page 373
9.3.3. Ras and the mitogen-activated protein kinase (MAPK) cascades......Page 384
9.3.4. Serine/threonine protein phosphatases and ezrin/radixin/moesin proteins......Page 388
9.3.5. Other signaling events in neutrophils......Page 390
9.4. Regulation of G-protein-effector coupling......Page 394
9.5. Integration of the signaling pathways......Page 395
References......Page 396
2. Sperm Motility......Page 426
2.1. The flagellum......Page 427
2.3. Techniques for measuring sperm motility......Page 429
2.3.1. Determination of the sperm head position as a function of time......Page 430
2.4. Types of sperm motility in different species......Page 431
2.5. Types of sperm motility within the female genital tract......Page 432
3. Criteria and Assays for Sperm Chemotaxis......Page 435
3.1.2. Sperm accumulation in a descending chemoattractant gradient......Page 436
3.1.3. Choice assays......Page 438
3.2. Directionality assays......Page 439
4. Chemotaxis of Nonmammalian Spermatozoa......Page 441
5. Chemotaxis of Mammalian Spermatozoa......Page 444
5.1. Early observations interpreted as sperm chemotaxis......Page 445
5.2.2. Chemotaxis to other fluids......Page 446
5.3. Mammalian sperm chemoattractants......Page 448
5.3.1. Progesterone......Page 449
5.3.2. Atrial natriuretic peptide (ANP)......Page 450
5.3.4. Other substances in follicular fluid......Page 451
5.3.6. Other potential chemoattractants and chemorepellents......Page 452
5.4.1. Involvement in fertilization......Page 453
5.4.2. Role in fertilization......Page 454
5.4.3. Potential locations of sperm chemotaxis in vivo......Page 456
6. Species Specificity of Sperm Chemotaxis......Page 459
7. Molecular Mechanism of Sperm Chemotaxis......Page 460
References......Page 462
1. Growthcone Guidance by Short- and Long-Range Cues......Page 473
2.1.2. Maxillary arch......Page 475
2.1.3. Floor plate......Page 476
2.2.1. Septum......Page 479
2.2.3. Floor plate......Page 480
2.2.4. Roof plate......Page 483
3.1.1. Netrins......Page 484
3.1.2. Class III semaphorins......Page 486
3.1.3. Slits......Page 487
5. Future Challenges......Page 488
References......Page 489
1. Motility Mechanisms......Page 494
2. Behavioral Mechanisms of Chemotaxis......Page 496
3. Molecular Mechanisms of Chemotaxis......Page 497
4. Other Taxes......Page 499
4.1. Thermotaxis......Page 500
4.2. Phototaxis......Page 501
References......Page 502
Index......Page 505