Tim Otter

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We have constructed a computational platform suitable for examining emergence of shape homeostasis in simple three-dimensional cellular systems. An embryo phenotype results from a developmental process starting with a single cell and its genome. When coupled to an evolutionary search, this platform can evolve embryos with particular stable shapes and high(More)
Choice models in marketing and economics are generally derived without specifying the underlying cognitive process of decision making. This approach has been successfully used to predict choice behavior. However, it has not much to say about such aspects of decision making as deliberation, attention, conflict, and cognitive limitations and how these(More)
Trifluoperazine (TFP), a drug that binds to Ca2+-calmodulin (CaM) complexes, altered swimming behavior not only in living paramecia, but also in reactivated, Triton-extracted "models" of the ciliate. By comparing the responses of living cells and models, we have ascertained that two sites of drug action exist in paramecium cilia. Swimming movements were(More)
Two distinctly different ATPases have been reported to be endogenous to the mitotic apparatus: a Mg2+-ATPase resembling axonemal dynein, and a Ca2+-ATPase postulated to be bound in membranes. To examine the nature of the Mg2+-ATPase, we isolated membrane-free mitotic spindles from Stronglylocentrotus droebachiensis embryos by rapidly lysing these in a(More)
Two distinctly different ATPases have been reported to be endogenous to the mitotic apparatus: a Mg 2+-ATPase resembling axonemal dynein, and a Ca t+-ATPase postulated to be bound in membranes. To examine the nature of the Mgt+-ATPase, we isolated membrane-free mitotic spindles from Strongylocentrotus droebachiensis embryos by rapidly lysing them in a(More)
The behaviour of swimming Paramecium is markedly affected by hydrostatic pressure (50-200 atm, 1 atm = 101 325 Pa). To investigate whether pressure might alter behaviour by acting directly on specific ion channels that mediate the behavioural responses, we examined the effects of K+, Na+ and Ba2+ ions on swimming speed and the reversal response during(More)
A hydrostatic pressure of only 68 atmospheres prevented swimming Paramecium caudatum from "avoiding" or reversing direction; 170 atmospheres stopped or decreased forward velocity by more than 75 percent. A decompression of 40 atmospheres invoked a single reversal, even at ,80 atmospheres. In contrast, 170 atmospheres did not significantly affect swimming(More)
Building effective computational models of living systemsrequires both a sound conceptual basis and an accurate scheme ofimplementation. Basic biological principles must be clearlyarticulated to capture their essential features or logic but notreach beyond legitimate bounds. This paper analyzes therelationships among genotype, phenotype, and ontogeny,(More)
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