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Some Dicty reading, movies you might find useful/fun
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 A. | The following represents a tiny smattering of the available literature on topics relevant to your quest for interesting (yet executable!) slime mold experiments. It's here to tweak your interest, provide a little jumpstart, give you a taste of what's out there, etc.
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B. | There's a tutorial on accessing e-journals at UA under the homepage References link; many of these articles can be accessed that way, though there's nothing wrong with reading an actual physical manuscript from time to time...
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 II. | Ammonia and Dicty aggregation, fruiting body formation
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A. | Cell, Vol 75, 321-327, 22 October 1993
Article
The target of ammonia action in dictyostelium
Lynne Davies,* Michel Satre,† Jean-Baptiste Martin,‡ and Julian D. Gross*
* Department of Biochemistry University of Oxford Oxford OX1 3QU, England
† Laboratoire de Biologie Cellulaire (CNRS) en Biologie et Médecine Département de Biologie Moléculaire et Structurale Centre d'Etudes Nucléaires 38041 Grenoble cedex, France
‡ Laboratoire de Résonance Magnétique en Biologie et Médecine Département de Biologie Moléculaire et Structurale Centre d'Etudes Nucléaires 38041 Grenoble cedex, France
Summary
The weak base ammonia is implicated in a number of key processes in Dictyostelium development, notably aggregation and culmination. To determine its intracellular site of action, we compared its biological potency with that of other weak bases. All the bases inhibited these developmental processes effectively, but differed manyfold in potency in accordance with their activity in dissipating pH gradients, as measured by in vivo 31P NMR with pH-sensitive phosphonate probes. These results indicate that weak bases influence development by raising the pH of an intracellular acidic compartment.
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III. | Thermotaxis and phototaxis in Dicty slugs
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A. | Genetics, Vol 137, 977-985, Copyright © 1994
INVESTIGATIONS
Genetic Analysis of Dictyostelium Slug Phototaxis Mutants
P. K. Darcy, Z. Wilczynska and P. R. Fisher
Present address: St. Vincent's Institute of Medical Research, 41 Victoria Parade, Melbourne, VIC 3065, Australia.
Mapping and complementation analysis with 17 phototaxis mutations has established 11 complementation groups phoA-phoK distributed over six linkage groups. Statistical calculations from the complementation data yielded 17 as the maximum likelihood estimate of the number of pho genes assuming all loci are equally mutable. Most of the phototaxis mutants were found to exhibit bimodal phototaxis and all were found to be impaired in positive thermotaxis supporting convergence of the photosensory and thermosensory pathways. The thermotaxis mutant HPF228 was unaltered in phototaxis suggesting that the mutation in this strain affects a gene product whose site of action is before the convergence of the two pathways. Other phenotypes such as multiple tip formation by aggregates, stumpy fruiting bodies with short or absent stalks and short migration were associated with some pho alleles suggesting multiple biological roles for some gene products important in phototransduction.
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IV. | Diffusible molecules and D. discoideum development
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A. | Development, Vol 103, Issue 1 1-16, Copyright © 1988 by Company of Biologists
JOURNAL ARTICLES
The role of diffusible molecules in regulating the cellular differentiation of Dictyostelium discoideum
JG Williams
A central problem in developmental biology is to understand how morphogenetic fields are created and how they act to direct regionalized cellular differentiation. This goal is being pursued in organisms as diverse as moulds, worms, flies, frogs and mice. Each organism has evolved its own solution to the challenge of multicellularity but there appear to be common underlying principles and, once pattern formation is fully understood in any system, some general truths seem certain to be revealed. As a non-obligate metazoan, Dictyostelium discoideum has proven a particularly tractable system in which to identify and characterize cellular morphogens. Cyclic AMP and ammonia stimulate prespore cell differentiation and ammonia plays an additional role in repressing terminal cellular differentiation. Differentiation Inducing Factor (DIF) acts to direct prestalk cell differentiation and adenosine may play a synergistic role in repressing prespore cell differentiation. This review summarizes the evidence for these interactions and describes a number of models which show how this small repertoire of diffusible molecules, acting in concert, may direct the formation of a differentiated structure.
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V. | The whorls of Polysphondylium pallidum
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A. | Development, Vol 105, Issue 2 323-333 Copyright © 1989 by Company of Biologists
Journal Articles
Spots and stripes: the patterning spectrum in the cellular slime mould Polysphondylium pallidum
JG McNally and EC Cox
Whorls of the cellular slime mould Polysphondylium pallidum originate as spherical cell masses that during normal morphogenesis produce tips only at equidistant positions around their equator. We have observed a series of new patterns in whorls that differ from normal whorls only in that they are larger or more elongated. Among the novel patterns found were arrays of tips distributed fairly regularly over the whole whorl surface, as well as striped patterns detected at earlier stages with a tip-specific antigen. These altered patterns demonstrate that a whorl's size and shape are by themselves important factors in pattern determination. We have compared the range of observed patterns to those predicted by a variety of different theories. We find that while no one theory can account in detail for all of our observations, predictions based on Turing's scheme of pattern formation come the closest.
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VI. | Phototaxis and fruiting body size
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A. | Biol Bull 128: 51-57. (February 1965)
THE RELATION OF SOROCARP SIZE TO PHOTOTAXIS IN THE CELLULAR SLIME MOLD, DICTYOSTELIUM PURPUREUM
JOHN TYLER BONNER 1 and FRANCES ELIZABETH WHITFIELD 1
1 Department of Biology, Princeton University, Princeton, New Jersey
Large fruiting bodies of the cellular slime mold, Dictyostelium purpureum, orient more effectively towards a source of light of low intensity than do small ones. The threshold of sensitivity can be changed either by changes in size of the sorocarp or by changes in the light intensity. However, in chemical gradients small cell masses are as sensitive as large ones. Therefore, if orientation to light is of adaptive value, selection pressure for size increase would be expected.
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VII. | Ammonia and slug phototaxis
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A. | PNAS | June 1, 1988 | vol. 85 | no. 11 | 3885-3887
Copyright © 1988 by the National Academy of Sciences
The Possible Role of Ammonia in Phototaxis of Migrating Slugs of Dictyostelium discoideum
J. T. Bonner, A. Chiang, J. Lee, and H. B. Suthers
Previously we showed that the rising cell masses of cellular slime molds orient away from high concentrations of ammonia gas, presumably by speeding up the cells on one side. Here we show that in the same way NH3 could also be involved in the highly sensitive phototaxis found in the migrating slugs of Dictyostelium discoideum. We have evidence that light increases their speed of migration and their production of NH3. Since unilateral light is concentrated on the distal side of a cell mass by the ``lens effect,'' this leads to the obvious hypothesis that the light stimulates the local production of NH3, which, in turn, stimulates the cells in the illuminated region to move faster.
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VIII. | Kin recognition in aggregation
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A. | Nature 442, 881-882 (24 August 2006) | doi:10.1038/442881a; Received 16 January 2006; Accepted 29 June 2006; Published online 23 August 2006
Social evolution: Kin preference in a social microbe
Natasha J. Mehdiabadi1, Chandra N. Jack1, Tiffany Talley Farnham1, Thomas G. Platt1,3, Sara E. Kalla1, Gad Shaulsky2, David C. Queller1 and Joan E. Strassmann1
Kin recognition helps cooperation to evolve in many animals1, but it is uncertain whether microorganisms can also use it to focus altruistic behaviour on relatives. Here we show that the social amoeba Dictyostelium purpureum prefers to form groups with its own kin in situations where some individuals die to assist others. By directing altruism towards kin, D. purpureum should generally avoid the costs of chimaerism2, 3 experienced by the related D. discoideum.
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IX. | Slug racing (paper focuses on slugs of mixed origin, but might stimulate some ideas on slug observation and measurement)
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A. | The costs and benefits of being a chimera
Issue Volume 269, Number 1507/November 22, 2002
Pages 2357-2362
Authors
Kevin R. Foster1, Angelo Fortunato1, Joan E. Strassmann1, David C. Queller1
1Department of Ecology and Evolutionary Biology, Rice University, MS 170, 6100 Main, Houston, TX 77005, USA
Abstract
Most multicellular organisms are uniclonal. This is hypothesized to be because uniclonal organisms function better than chimeras (non-clonal organisms), owing to reduced levels of internal genetic conflict. We tested this idea using the social amoeba or slime mold Dictyostelium discoideum. When starving, the normally solitary amoebae aggregate to form a differentiated multicellular slug that migrates towards light and forms a fruiting body, facilitating the dispersal of spores. We added 107 amoebae to Petri plates containing 1, 2, 5 or 10 clones mixed together. We found an intrinsic cost to chimerism: chimeric slugs moved significantly less far than uniclonal slugs of the same size. However, in nature, joining with other clones to form a chimera should increase slug size, and larger slugs travel further. We incorporated this size effect into a second experiment by giving chimeras more cells than single clones (single clones had 106 cells, two-clone chimeras had 2 2 106 cells and so on). The uniclonal treatments then simulated a clone in a mixture that refuses to form chimeras. In this experiment, chimeras moved significantly further than the uniclonal slugs, in spite of the intrinsic cost. Thus, chimerism is costly, which may be why it evolves so seldom, but in D. discoideum the benefits of large size appear to compensate.
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X. | Observations and modeling of chemical waves in slugs (light, cAMP, ammonia)
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XI. | General Dictyostelium website with movies, info
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XII. | Incredible collection of Quicktime movies of Slime Mold Biology
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 B. | Some recommended titles:
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1. | Dicty discoideum-- slug migration
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2. | Dicty discoideum--negative taxis of slug to ammonia
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3. | Dicty discoideum--fruting body formation
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4. | Dicty polycephalum fruiting (1)--multi-headed fruits
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5. | Dicty giganteum phototaxis of slugs
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