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The Social Amoebae

The Social Amoebae: The Biology of Cellular Slime Molds

John Tyler Bonner
Copyright Date: 2009
Pages: 156
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  • Book Info
    The Social Amoebae
    Book Description:

    Noted biologist and author John Tyler Bonner has experimented with cellular slime molds for more than sixty years, and he has done more than anyone else to raise these peculiar collections of amoebae from a minor biological curiosity to a major model organism--one that is widely studied for clues to the development and evolution of all living things. Now, five decades after he published his first pioneering book on cellular slime molds, Bonner steps back from the proliferating and increasingly specialized knowledge about the organism to provide a broad, nontechnical picture of its whole biology, including its evolution, sociobiology, ecology, behavior, and development.The Social Amoebaedraws the big lessons from decades of research, and shows how slime molds fit into and illuminate biology as a whole.

    Slime molds are very different from other organisms; they feed as individual amoebae before coming together to form a multicellular organism that has a remarkable ability to move and orient itself in its environment. Furthermore, these social amoebae display a sophisticated division of labor; within each organism, some cells form the stalk and others become the spores that will seed the next generation. InThe Social Amoebae, Bonner examines all these parts together, giving a balanced, concise, and clear overview of slime mold biology, from molecules to cells to multicells, as he advances some unconventional and unexpected insights.

    eISBN: 978-1-4008-3328-3
    Subjects: Biological Sciences, Developmental & Cell Biology, Ecology & Evolutionary Biology

Table of Contents

  1. Front Matter
    (pp. i-iv)
  2. Table of Contents
    (pp. v-vi)
  3. Preface
    (pp. vii-xii)
  4. 1 Introduction
    (pp. 1-6)

    Evolution, cell biology, biochemistry, and developmental biology have made extraordinary progress in the last hundred years—much of it since I was weaned on schoolboy biology in the 1930s. Most striking of all is the sudden eruption of molecular biology starting in the 1950s. I will make a reckless generalization that each one of these surges was due to a collision with genetics. Perhaps it would be more accurate to say that they fused rather than just collided, because in each case an extraordinary fruitful symbiosis was the result. First, at the beginning of this century, genetics fused with nineteenth-century...

  5. 2 The Life Cycle
    (pp. 7-16)

    One of the most striking things about cellular slime molds is their life cycle; it is so different. I remember the times when I first gave lectures on my experiments in the 1940s, and at question time the audiences of biologists seemed to show no interest in all the clever things I thought I had done, but they wanted to know more of what was then an unheard-of life cycle. Now that cycle can be found in every elementary biology textbook.

    All the organisms with which we are most familiar, both animal and plant, including ourselves, start as a single...

  6. 3 Evolution
    (pp. 17-34)

    We want to know how and why amoebae became social in the first place. This key question revolves around a second question: what advantage does togetherness provide them, or, to put it in a better form, how could it have been encouraged by natural selection?

    To begin, becoming multicellular means an increase in size, and this is directly related to the key matter of dispersal. Organisms that have an effective mechanism for spreading, for dispersing, can more easily find new sources of food and multiply. Natural selection involves competition—a struggle for existence—and the victors are the ones that...

  7. 4 Ecology
    (pp. 35-42)

    There are some species of cellular slime molds that are found everywhere and others that seem to be restricted in their distribution. Our most comprehensive understanding of slime mold distribution comes from the work of James Cavender and his co-workers.22They show that a number of cosmopolitan species are found everywhere, other species are found in large geographic areas, such as the tropics or a major area of a continent, and still others are endemic and found on islands such as New Zealand.23

    They also point out that cellular slime molds are primarily associated with forest soils, and they are...

  8. 5 Behavior of Amoebae and Cell Masses
    (pp. 43-86)

    One aspect of experimental work on cellular slime molds that has received more attention than any other is the chemotaxis of the individual amoebae. It was not known for certain until the 1940s that aggregation involved chemotaxis, although, without any evidence, the idea was put forth in the early literature. Once the mechanism was firmly established, there was the next question: What was the chemical nature of the attractant?

    In the late 1960s it was discovered that the acrasin ofD. discoideumwas 3´-5´-cyclic adenosine monophosphate, or cyclic AMP.38As a result, the number of studies on slime mold chemotaxis...

  9. 6 Morphogenesis
    (pp. 87-94)

    The variety of shapes of cellular slime molds has been admirably summarized by Pauline Schaap and Sandie Baldauf and their colleagues: as was discussed earlier, they did a molecular phylogeny of seventy-five species and separated them into four groups. The largest and most recent species were members of group 4 (fig. 4).91They consist mostly of simple fruiting bodies with a single stalk capped by one terminal spore mass. The model slime moldD. discoideumis a member of this group.

    Another member of the group is an interesting exception, for it has multiple sori.D. rosariumis a fairly...

  10. 7 Differentiation
    (pp. 95-120)

    For the cellular slime molds, differentiation involves the division of labor between stalk cells and spores. It is true that some species have at the base of their stalk special structures such as a basal disc or a crampon anchor that are made up of vacuolated cells similar to stalk cells; they represent another way in which the labor is divided. However, I will stick to the main stalk-spore division. It clearly is the matter of central interest, and a vast literature on the subject has accumulated. Not only are there fascinating matters of descriptive and general biological interest, but...

  11. 8 The Future
    (pp. 121-128)

    In trying to give a general picture of what we know about slime molds, I have neglected much of the recent research. I have done this consciously because for almost every issue that I have brought up the plot keeps thickening. It has to do with the very nature of the molecular biology of slime molds today. For many of the phenomena I have discussed, and this is especially true of the discussion of their development, one wants to understand the molecular events that led to the final result. One wants to fully analyze all the events. For instance, take...

  12. Bibliography
    (pp. 129-140)
  13. Index
    (pp. 141-144)